Publications by authors named "Joel G Fletcher"

254 Publications

Deep-learning model observer for a low-contrast hepatic metastases localization task in computed tomography.

Med Phys 2021 Nov 18. Epub 2021 Nov 18.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Purpose: Conventional model observers (MO) in CT are often limited to a uniform background or varying background that is random and can be modeled in an analytical form. It is unclear if these conventional MOs can be readily generalized to predict human observer performance in clinical CT tasks that involve realistic anatomical background. Deep-learning-based model observers (DL-MO) have recently been developed, but have not been validated for challenging low contrast diagnostic tasks in abdominal CT. We consequently sought to validate a DL-MO for a low-contrast hepatic metastases localization task.

Methods: We adapted our recently developed DL-MO framework for the liver metastases localization task. Our previously-validated projection-domain lesion-/noise-insertion techniques were used to synthesize realistic positive and low-dose abdominal CT exams, using the archived patient projection data. Ten experimental conditions were generated, which involved different lesion sizes/contrasts, radiation dose levels, and image reconstruction types. Each condition included 100 trials generated from a patient cohort of 7 cases. Each trial was presented as liver image patches (160×160×5 voxels). The DL-MO performance was calculated for each condition and was compared with human observer performance, which was obtained by three sub-specialized radiologists in an observer study. The performance of DL-MO and radiologists was gauged by the area under localization receiver-operating-characteristic curves. The generalization performance of the DL-MO was estimated with the repeated twofold cross-validation method over the same set of trials used in the human observer study. A multi-slice Channelized Hoteling Observers (CHO) was compared with the DL-MO across the same experimental conditions.

Results: The performance of DL-MO was highly correlated to that of radiologists (Pearson's correlation coefficient: 0.987; 95% CI: [0.942, 0.997]). The performance level of DL-MO was comparable to that of the grouped radiologists, that is, the mean performance difference was -3.3%. The CHO performance was poorer than the grouped radiologist performance, before internal noise could be added. The correlation between CHO and radiologists was weaker (Pearson's correlation coefficient: 0.812, and 95% CI: [0.378, 0.955]), and the corresponding performance bias (-29.5%) was statistically significant.

Conclusion: The presented study demonstrated the potential of using the DL-MO for image quality assessment in patient abdominal CT tasks.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/mp.15362DOI Listing
November 2021

Impact of dual-energy 50-keV virtual monoenergetic images on radiologist confidence in detection of key imaging findings of small hepatocellular carcinomas using multiphase liver CT.

Acta Radiol 2021 Nov 1:2841851211052993. Epub 2021 Nov 1.

Department of Radiology, 6915Mayo Clinic, Rochester, MN, USA.

Background: Dual-energy virtual monoenergetic images can increase iodine signal, potentially increasing the conspicuity of hepatic masses.

Purpose: To determine if dual-energy 50-keV virtual monoenergetic images improve visualization of key imaging findings or diagnostic confidence for small (≤2 cm) hepatocellular carcinomas (HCC) at multiphase, contrast-enhanced liver computed tomography (CT).

Material And Methods: Patients with chronic liver disease underwent multiphase dual-energy CT imaging for HCC, with late arterial and delayed phase dual-energy 50-keV images reconstructed. Two non-reader subspecialized gastrointestinal (GI) radiologists established the reference standard, determining the location and diagnosis of all hepatic lesions using predetermined criteria. Three GI radiologists interpreted mixed kV CT images without or with dual-energy 50-keV images. Radiologists identified potential HCCs and rated their confidence (0-100 scales) in imaging findings of arterial enhancement, enhancing capsule, tumor washout, and LI-RADS 5 (2018) category.

Results: In total, 45 patients (14 women; mean age = 59.5 ± 10.9 years) with chronic liver disease were included. Of them, 19 patients had 25 HCCs ≤2 cm (mean size = 1.5 ± 0.4 cm). There were 17 LI-RADS 3 and 4 lesions and 19 benign lesions. Reader confidence in imaging findings of arterial enhancement, enhancing capsule, and non-peripheral washout significantly increased with dual-energy images ( ≤ 0.022). Overall confidence in HCC diagnosis increased significantly with dual-energy 50-keV images (52.4 vs. 68.8;  = 0.001). Dual-energy images demonstrated a slight but significant decrease in overall image quality.

Conclusion: Radiologist confidence in key imaging features of small HCCs and confidence in imaging diagnosis increases with use of dual-energy 50-keV images at multiphase, contrast-enhanced liver CT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/02841851211052993DOI Listing
November 2021

A Pilot Study to Estimate the Impact of High Matrix Image Reconstruction on Chest Computed Tomography.

J Clin Imaging Sci 2021 30;11:52. Epub 2021 Sep 30.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States.

Objectives: The objectives of the study were to estimate the impact of high matrix image reconstruction on chest computed tomography (CT) compared to standard image reconstruction.

Material And Methods: This retrospective study included patients with interstitial or parenchymal lung disease, airway disease, and pulmonary nodules who underwent chest CT. Chest CT images were reconstructed using high matrix (1024 × 1024) or standard matrix (512 × 512), with all other parameters matched. Two radiologists, blinded to reconstruction technique, independently examined each lung, viewing image sets side by side and rating the conspicuity of imaging findings using a 5-point relative conspicuity scale. The presence of pulmonary nodules and confidence in classification of internal attenuation was also graded. Overall image quality and subjective noise/artifacts were assessed.

Results: Thirty-four patients with 68 lungs were evaluated. Relative conspicuity scores were significantly higher using high matrix image reconstruction for all imaging findings indicative of idiopathic lung fibrosis (peripheral airway visualization, interlobular septal thickening, intralobular reticular opacity, and end-stage fibrotic change; ≤ 0.001) along with emphysema, mosaic attenuation, and fourth order bronchi for both readers ( ≤ 0.001). High matrix reconstruction did not improve confidence in the presence or classification of internal nodule attenuation for either reader. Overall image quality was increased but not subjective noise/artifacts with high matrix image reconstruction for both readers ( < 0.001).

Conclusion: High matrix image reconstruction significantly improves the conspicuity of imaging findings reflecting interstitial lung disease and may be useful for diagnosis or treatment response assessment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.25259/JCIS_143_2021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8492437PMC
September 2021

An interactive eye-tracking system for measuring radiologists' visual fixations in volumetric CT images: Implementation and initial eye-tracking accuracy validation.

Med Phys 2021 Nov 6;48(11):6710-6723. Epub 2021 Oct 6.

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Purpose: Eye-tracking approaches have been used to understand the visual search process in radiology. However, previous eye-tracking work in computer tomography (CT) has been limited largely to single cross-sectional images or video playback of the reconstructed volume, which do not accurately reflect radiologists' visual search activities and their interactivity with three-dimensional image data at a computer workstation (e.g., scroll, pan, and zoom) for visual evaluation of diagnostic imaging targets. We have developed a platform that integrates eye-tracking hardware with in-house-developed reader workstation software to allow monitoring of the visual search process and reader-image interactions in clinically relevant reader tasks. The purpose of this work is to validate the spatial accuracy of eye-tracking data using this platform for different eye-tracking data acquisition modes.

Methods: An eye-tracker was integrated with a previously developed workstation designed for reader performance studies. The integrated system captured real-time eye movement and workstation events at 1000 Hz sampling frequency. The eye-tracker was operated either in head-stabilized mode or in free-movement mode. In head-stabilized mode, the reader positioned their head on a manufacturer-provided chinrest. In free-movement mode, a biofeedback tool emitted an audio cue when the head position was outside the data collection range (general biofeedback) or outside a narrower range of positions near the calibration position (strict biofeedback). Four radiologists and one resident were invited to participate in three studies to determine eye-tracking spatial accuracy under three constraint conditions: head-stabilized mode (i.e., with use of a chin rest), free movement with general biofeedback, and free movement with strict biofeedback. Study 1 evaluated the impact of head stabilization versus general or strict biofeedback using a cross-hair target prior to the integration of the eye-tracker with the image viewing workstation. In Study 2, after integration of the eye-tracker and reader workstation, readers were asked to fixate on targets that were randomly distributed within a volumetric digital phantom. In Study 3, readers used the integrated system to scroll through volumetric patient CT angiographic images while fixating on the centerline of designated blood vessels (from the left coronary artery to dorsalis pedis artery). Spatial accuracy was quantified as the offset between the center of the intended target and the detected fixation using units of image pixels and the degree of visual angle.

Results: The three head position constraint conditions yielded comparable accuracy in the studies using digital phantoms. For Study 1 involving the digital crosshairs, the median ± the standard deviation of offset values among readers were 15.2 ± 7.0 image pixels with the chinrest, 14.2 ± 3.6 image pixels with strict biofeedback, and 19.1 ± 6.5 image pixels with general biofeedback. For Study 2 using the random dot phantom, the median ± standard deviation offset values were 16.7 ± 28.8 pixels with use of a chinrest, 16.5 ± 24.6 pixels using strict biofeedback, and 18.0 ± 22.4 pixels using general biofeedback, which translated to a visual angle of about 0.8° for all three conditions. We found no obvious association between eye-tracking accuracy and target size or view time. In Study 3 viewing patient images, use of the chinrest and strict biofeedback demonstrated comparable accuracy, while the use of general biofeedback demonstrated a slightly worse accuracy. The median ± standard deviation of offset values were 14.8 ± 11.4 pixels with use of a chinrest, 21.0 ± 16.2 pixels using strict biofeedback, and 29.7 ± 20.9 image pixels using general biofeedback. These corresponded to visual angles ranging from 0.7° to 1.3°.

Conclusions: An integrated eye-tracker system to assess reader eye movement and interactive viewing in relation to imaging targets demonstrated reasonable spatial accuracy for assessment of visual fixation. The head-free movement condition with audio biofeedback performed similarly to head-stabilized mode.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/mp.15219DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8595866PMC
November 2021

Perianal magnetic resonance imaging findings and their potential impact on outcome in children with perianal fistulizing Crohn disease.

Pediatr Radiol 2021 Dec 6;51(13):2481-2491. Epub 2021 Sep 6.

Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.

Background: Children with perianal fistulizing Crohn disease require intensive medical management but also have a higher risk for subsequent surgical interventions.

Objective: We performed a retrospective study to identify patient factors and perianal anatomical features by pelvic MR that are associated with surgical interventions in these children.

Materials And Methods: We included children with Crohn disease and perianal fistula who underwent pelvic MR with available, archived images and collected demographic, clinical and laboratory data. Radiologists reviewed pelvic MR exams and identified Park classification and additional anatomical features of perianal fistulas, including fistula branching, horseshoe ramifications, abscess, inflammatory mass, supralevator extension, anal sphincter damage, proctitis and posterior anal space involvement. We performed univariate and subsequent multivariate analysis to determine features associated with subsequent surgical intervention.

Results: Ninety-nine children with Crohn disease underwent pelvic MR. In this cohort, 69 children had no surgical interventions prior to baseline MRI, with subsequent median clinical follow-up of 5.5 years. Univariate analysis demonstrated that branching (P=0.009), supralevator extension (P=0.015) and anal sphincter damage (P=0.031) were significantly associated with subsequent surgical intervention. Age at baseline MRI was also associated with intervention (hazard ratio [HR] every 5 years: 2.13; 95% confidence interval [CI]: 1.18-3.83; P=0.012). A multivariable model identified only fistula branching (HR: 2.31; 95% CI: 1.28-4.15; P=0.005) and age (HR: 5.18; CI: 1.57-17.14; P=0.007) as independent predictors of subsequent surgery. No demographic, clinical or laboratory parameter predicted subsequent surgical intervention.

Conclusion: Age and anatomical MR features indicating fistula complexity (branching, supralevator extension) and sphincter damage confer a higher risk of subsequent surgical intervention in children with perianal Crohn disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00247-021-05158-wDOI Listing
December 2021

CT Noise-Reduction Methods for Lower-Dose Scanning: Strengths and Weaknesses of Iterative Reconstruction Algorithms and New Techniques.

Radiographics 2021 Sep-Oct;41(5):1493-1508

From the Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (P.M., L.Y., S.L., A.D.M., H.G., C.H.M., J.G.F.); Department of Radiology, Harborview Medical Center, Seattle, Wash (A.M.); Department of Medical Imaging, Toronto General Hospital, Toronto, ON, Canada (L.S.G.); and Department of Abdominal Imaging, University of Texas MD Anderson Cancer Center, Houston, Tex (C.T.J.).

Iterative reconstruction (IR) algorithms are the most widely used CT noise-reduction method to improve image quality and have greatly facilitated radiation dose reduction within the radiology community. Various IR methods have different strengths and limitations. Because IR algorithms are typically nonlinear, they can modify spatial resolution and image noise texture in different regions of the CT image; hence traditional image-quality metrics are not appropriate to assess the ability of IR to preserve diagnostic accuracy, especially for low-contrast diagnostic tasks. In this review, the authors highlight emerging IR algorithms and CT noise-reduction techniques and summarize how these techniques can be evaluated to help determine the appropriate radiation dose levels for different diagnostic tasks in CT. In addition to advanced IR techniques, we describe novel CT noise-reduction methods based on convolutional neural networks (CNNs). CNN-based noise-reduction techniques may offer the ability to reduce image noise while maintaining high levels of image detail but may have unique drawbacks. Other novel CT noise-reduction methods are being developed to leverage spatial and/or spectral redundancy in multiphase or multienergy CT. Radiologists and medical physicists should be familiar with these different alternatives to adapt available CT technology for different diagnostic tasks. The scope of this article is ) to review the clinical applications of IR algorithms as well as their strengths, weaknesses, and methods of assessment and ) to explore new CT image reconstruction and noise-reduction techniques that promise to facilitate radiation dose reduction. RSNA, 2021.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1148/rg.2021200196DOI Listing
November 2021

Dual-Contrast Biphasic Liver Imaging With Iodine and Gadolinium Using Photon-Counting Detector Computed Tomography: An Exploratory Animal Study.

Invest Radiol 2021 Aug 13. Epub 2021 Aug 13.

From the Department of Radiology, Mayo Clinic, Rochester, MN.

Purpose: The aims of this study were to develop a single-scan dual-contrast protocol for biphasic liver imaging with 2 intravenous contrast agents (iodine and gadolinium) and to evaluate its effectiveness in an exploratory swine study using a photon-counting detector computed tomography (PCD-CT) system.

Materials And Methods: A dual-contrast CT protocol was developed for PCD-CT to simultaneously acquire 2 phases of liver contrast enhancement, with the late arterial phase enhanced by 1 contrast agent (iodine-based) and the portal venous phase enhanced by the other (gadolinium-based). A gadolinium contrast bolus (gadobutrol: 64 mL, 8 mL/s) and an iodine contrast bolus (iohexol: 40 mL, 5 mL/s) were intravenously injected in the femoral vein of a healthy domestic swine, with the second injection initiated after 17 seconds from the beginning of the first injection; PCD-CT image acquisition was performed 12 seconds after the beginning of the iodine contrast injection. A convolutional neural network (CNN)-based denoising technique was applied to PCD-CT images to overcome the inherent noise magnification issue in iodine/gadolinium decomposition task. Iodine and gadolinium material maps were generated using a 3-material decomposition method in image space. A set of contrast samples (mixed iodine and gadolinium) was attached to the swine belly; quantitative accuracy of material decomposition in these inserts between measured and true concentrations was calculated using root mean square error. An abdominal radiologist qualitatively evaluated the delineation of arterial and venous vasculatures in the swine liver using iodine and gadolinium maps obtained using the dual-contrast PCD-CT protocol.

Results: The iodine and gadolinium samples attached to the swine were quantified with root mean square error values of 0.75 mg/mL for iodine and 0.45 mg/mL for gadolinium from the contrast material maps derived from the denoised PCD-CT images. Hepatic arteries containing iodine and veins containing gadolinium in the swine liver could be clearly visualized. Compared with the original images, better distinctions between 2 liver phases were achieved using CNN denoising, with approximately 60% to 80% noise reduction in contrast material maps acquired with the denoised PCD-CT images compared with the original images.

Conclusions: Simultaneous biphasic liver imaging in a single multienergy PCD-CT acquisition using a dual-contrast (iodine and gadolinium) injection protocol and CNN denoising was demonstrated in a swine study, where the enhanced hepatic arteries (containing iodine) and the enhanced hepatic veins (containing gadolinium) could be clearly visualized and delineated in the swine liver.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/RLI.0000000000000815DOI Listing
August 2021

The utility of a dual-phase, dual-energy CT protocol in patients presenting with overt gastrointestinal bleeding.

Acta Radiol Open 2021 Jul 27;10(7):20584601211030658. Epub 2021 Jul 27.

Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA.

Background: Due to their easy accessibility, CT scans have been increasingly used for investigation of gastrointestinal (GI) bleeding.

Purpose: To estimate the performance of a dual-phase, dual-energy (DE) GI bleed CT protocol in patients with overt GI bleeding in clinical practice and examine the added value of portal phase and DE images.

Materials And Methods: Consecutive patients with GI bleeding underwent a two-phase DE GI bleed CT protocol. Two gastroenterologists established the reference standard. Performance was estimated using clinical CT reports. Three GI radiologists rated confidence in GI bleeding in a subset of 62 examinations, evaluating first mixed kV arterial images, then after examining additional portal venous phase images, and finally after additional DE images (virtual non-contrast and virtual monoenergetic 50 keV images).

Results: 52 of 176 patients (29.5%) had GI bleeding by the reference standard. The overall sensitivity, specificity, and positive and negative predictive values of the CT GI bleed protocol for detecting GI bleeding were 65.4%, 89.5%, 72.3%, and 86.0%, respectively. In patients with GI bleeding, diagnostic confidence of readers increased after adding portal phase images to arterial phase images ( = 0.002), without additional benefit from dual energy images. In patients without GI bleeding, confidence in luminal extravasation appropriately decreased after adding portal phase, and subsequently DE images ( = 0.006, = 0.018).

Conclusion: A two-phase DE GI bleed CT protocol had high specificity and negative predictive value in clinical practice. Portal venous phase images improved diagnostic confidence in comparison to arterial phase images alone. Dual-energy images further improved radiologist confidence in the absence of bleeding.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/20584601211030658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8323435PMC
July 2021

MRI-detected extramural venous invasion of rectal cancer: Multimodality performance and implications at baseline imaging and after neoadjuvant therapy.

Insights Imaging 2021 Aug 9;12(1):110. Epub 2021 Aug 9.

Department of Radiology, Mayo Clinic, Rochester, 200 First Street SW, Rochester, MN, 55905, USA.

MRI is routinely used for rectal cancer staging to evaluate tumor extent and to inform decision-making regarding surgical planning and the need for neoadjuvant and adjuvant therapy. Extramural venous invasion (EMVI), which is intravenous tumor extension beyond the rectal wall on histopathology, is a predictor for worse prognosis. T2-weighted images (T2WI) demonstrate EMVI as a nodular-, bead-, or worm-shaped structure of intermediate T2 signal with irregular margins that arises from the primary tumor. Correlative diffusion-weighted images demonstrate intermediate to high signal corresponding to EMVI, and contrast enhanced T1-weighted images demonstrate tumor signal intensity in or around vessels. Diffusion-weighted and post contrast images may increase diagnostic performance but decrease inter-observer agreement. CT may also demonstrate obvious EMVI and is potentially useful in patients with a contraindication for MRI. This article aims to review the spectrum of imaging findings of EMVI of rectal cancer on MRI and CT, to summarize the diagnostic accuracy and inter-observer agreement of imaging modalities for its presence, to review other rectal neoplasms that may cause EMVI, and to discuss the clinical significance and role of MRI-detected EMVI in staging and restaging clinical scenarios.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13244-021-01023-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8353019PMC
August 2021

Reader Performance as a Function of Patient Size for the Detection of Hepatic Metastases.

J Comput Assist Tomogr 2021 Nov-Dec 01;45(6):812-819

From the Department of Radiology, Mayo Clinic, Rochester, MN.

Objective: To investigate reader performance as a function of patient size for the detection of hepatic metastases when an automatic exposure control (AEC) system is used, which varies image noise as a function of patient size.

Methods: Abdominal computed tomograhy examinations across 100, 120, 160, and 200 quality reference tube current-time product were collected, involving a cohort of 83 patients. Three radiologists identified hepatic metastases across all dose levels. Partial Spearman rank correlation and multivariate logistic regression were used to evaluate correlations between reader performance and patient size and lesion size/contrast while accounting for potential confounding effects. Analyses were repeated on an emulated less-variable noise AEC.

Results: No statistically significant correlation was observed between patient size and radiologist performance (for variable-noise AEC: range of partial Spearman ρ, -0.157 to -0.035]; range of adjusted odds ratios, 0.987, 1.006).

Conclusions: Reader performance was independent of patient size, suggesting that variable-noise AEC provides better modulation for larger patients than constant-noise AEC.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/RCT.0000000000001200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8599620PMC
January 2022

Biomarkers for the Prediction and Diagnosis of Fibrostenosing Crohn's Disease: A Systematic Review.

Clin Gastroenterol Hepatol 2021 Jun 2. Epub 2021 Jun 2.

Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio; Department of Gastroenterology, Hepatology, and Nutrition, Digestive Diseases and Surgery Institute, Cleveland Clinic Foundation, Cleveland, Ohio.

Background And Aims: Intestinal strictures are a common complication of Crohn's disease (CD). Biomarkers of intestinal strictures would assist in their prediction, diagnosis, and monitoring. Herein we provide a comprehensive systematic review of studies assessing biomarkers that may predict or diagnose CD-associated strictures.

Methods: We performed a systematic review of PubMed, EMBASE, ISI Web of Science, Cochrane Library, and Scopus to identify citations pertaining to biomarkers of intestinal fibrosis through July 6, 2020, that used a reference standard of full-thickness histopathology or cross-sectional imaging or endoscopy. Studies were categorized based on the type of biomarker they evaluated (serum, genetic, histopathologic, or fecal).

Results: Thirty-five distinct biomarkers from 3 major groups were identified: serum (20 markers), genetic (9 markers), and histopathology (6 markers). Promising markers include cartilage oligomeric matrix protein, hepatocyte growth factor activator, and lower levels of microRNA-19-3p (area under the curves were 0.805, 0.738, and 0.67, respectively), and multiple anti-flagellin antibodies (A4-Fla2 [odds ratio, 3.41], anti Fla-X [odds ratio, 2.95], and anti-CBir1 [multiple]). Substantial heterogeneity was observed and none of the markers had undergone formal validation. Specific limitations to acceptance of these markers included failure to use a standardized definition of stricturing disease, lack of specificity, and insufficient relevance to the pathogenesis of intestinal strictures or incomplete knowledge regarding their operating properties.

Conclusions: There is a lack of well-defined studies on biomarkers of intestinal stricture. Development of reliable and accurate biomarkers of stricture is a research priority. Biomarkers can support the clinical management of CD patients and aid in the stratification and monitoring of patients during clinical trials of future antifibrotic drug candidates.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cgh.2021.05.054DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8636551PMC
June 2021

International consensus to standardise histopathological scoring for small bowel strictures in Crohn's disease.

Gut 2021 May 5. Epub 2021 May 5.

Department of Inflammation and Immunity, Cleveland Clinic Foundation, Cleveland, Ohio, USA

Objective: Effective medical therapy and validated trial outcomes are lacking for small bowel Crohn's disease (CD) strictures. Histopathology of surgically resected specimens is the gold standard for correlation with imaging techniques. However, no validated histopathological scoring systems are currently available for small bowel stricturing disease. We convened an expert panel to evaluate the appropriateness of histopathology scoring systems and items generated based on panel opinion.

Design: Modified RAND/University of California Los Angeles methodology was used to determine the appropriateness of 313 candidate items related to assessment of CD small bowel strictures.

Results: In this exercise, diagnosis of naïve and anastomotic strictures required increased bowel wall thickness, decreased luminal diameter or internal circumference, and fibrosis of the submucosa. Specific definitions for stricture features and technical sampling parameters were also identified. Histopathologically, a stricture was defined as increased thickness of all layers of the bowel wall, fibrosis of the submucosa and bowel wall, and muscularisation of the submucosa. Active mucosal inflammatory disease was defined as neutrophilic inflammation in the lamina propria and any crypt or intact surface epithelium, erosion, ulcer and fistula. Chronic mucosal inflammatory disease was defined as crypt architectural distortion and loss, pyloric gland metaplasia, Paneth cell hyperplasia, basal lymphoplasmacytosis, plasmacytosis and fibrosis, or prominent lymphoid aggregates at the mucosa/submucosa interface. None of the scoring systems used to assess CD strictures were considered appropriate for clinical trials.

Conclusion: Standardised assessment of gross pathology and histopathology of CD small bowel strictures will improve clinical trial efficiency and aid drug development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/gutjnl-2021-324374DOI Listing
May 2021

Challenges in Diagnosis and Management of Hemobilia.

Radiographics 2021 May-Jun;41(3):802-813

From the Departments of Radiology (A.P., J.G.F., S.K.V., J.L.F., A.R.K.) and Gastroenterology (A.C.S.), Mayo Clinic, 200 First St SW, Rochester MN 55905.

Hemobilia, or hemorrhage within the biliary system, is an uncommon form of upper gastrointestinal (GI) bleeding that presents unique diagnostic and therapeutic challenges. Most cases are the result of iatrogenic trauma, although accidental trauma and a variety of inflammatory, infectious, and neoplastic processes have also been implicated. Timely diagnosis can often be difficult, as the classic triad of upper GI hemorrhage, biliary colic, and jaundice is present in a minority of cases, and there may be considerable delay in the onset of bleeding after the initial injury. Therefore, the radiologist must maintain a high index of suspicion for this condition and be attuned to its imaging characteristics across a variety of modalities. CT is the first-line diagnostic modality in evaluation of hemobilia, while catheter angiography and endoscopy play vital and complementary roles in both diagnosis and treatment. The authors review the clinical manifestations and multimodality imaging features of hemobilia, describe the wide variety of underlying causes, and highlight key management considerations.RSNA, 2021.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1148/rg.2021200192DOI Listing
November 2021

Deep-learning-based direct synthesis of low-energy virtual monoenergetic images with multi-energy CT.

J Med Imaging (Bellingham) 2021 Sep 19;8(5):052104. Epub 2021 Apr 19.

Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States.

We developed a deep learning method to reduce noise and beam-hardening artifact in virtual monoenergetic image (VMI) at low x-ray energy levels. An encoder-decoder type convolutional neural network was implemented with customized inception modules and in-house-designed training loss (denoted as Incept-net), to directly estimate VMI from multi-energy CT images. Images of an abdomen-sized water phantom with varying insert materials were acquired from a research photon-counting-detector CT. The Incept-net was trained with image patches ( ) extracted from the phantom data, as well as synthesized, random-shaped numerical insert materials. The whole CT images ( ) with the remaining real insert materials that were unseen in network training were used for testing. Seven contrast-enhanced abdominal CT exams were used for preliminary evaluation of Incept-net generalizability over anatomical background. Mean absolute percentage error (MAPE) was used to evaluate CT number accuracy. Compared to commercial VMI software, Incept-net largely suppressed beam-hardening artifact and reduced noise (53%) in phantom study. Incept-net presented comparable CT number accuracy at higher-density ( -value [0.0625, 0.999]) and improved it at lower-density inserts ( ) with overall MAPE: Incept-net [2.9%, 4.6%]; commercial-VMI [6.7%, 10.9%]. In patient images, Incept-net suppressed beam-hardening artifact and reduced noise (up to 50%, ). In this preliminary study, Incept-net presented the potential to improve low-energy VMI quality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/1.JMI.8.5.052104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8054272PMC
September 2021

Quality gaps in public pancreas imaging datasets: Implications & challenges for AI applications.

Pancreatology 2021 Aug 2;21(5):1001-1008. Epub 2021 Apr 2.

Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA. Electronic address:

Objective: Quality gaps in medical imaging datasets lead to profound errors in experiments. Our objective was to characterize such quality gaps in public pancreas imaging datasets (PPIDs), to evaluate their impact on previously published studies, and to provide post-hoc labels and segmentations as a value-add for these PPIDs.

Methods: We scored the available PPIDs on the medical imaging data readiness (MIDaR) scale, and evaluated for associated metadata, image quality, acquisition phase, etiology of pancreas lesion, sources of confounders, and biases. Studies utilizing these PPIDs were evaluated for awareness of and any impact of quality gaps on their results. Volumetric pancreatic adenocarcinoma (PDA) segmentations were performed for non-annotated CTs by a junior radiologist (R1) and reviewed by a senior radiologist (R3).

Results: We found three PPIDs with 560 CTs and six MRIs. NIH dataset of normal pancreas CTs (PCT) (n = 80 CTs) had optimal image quality and met MIDaR A criteria but parts of pancreas have been excluded in the provided segmentations. TCIA-PDA (n = 60 CTs; 6 MRIs) and MSD(n = 420 CTs) datasets categorized to MIDaR B due to incomplete annotations, limited metadata, and insufficient documentation. Substantial proportion of CTs from TCIA-PDA and MSD datasets were found unsuitable for AI due to biliary stents [TCIA-PDA:10 (17%); MSD:112 (27%)] or other factors (non-portal venous phase, suboptimal image quality, non-PDA etiology, or post-treatment status) [TCIA-PDA:5 (8.5%); MSD:156 (37.1%)]. These quality gaps were not accounted for in any of the 25 studies that have used these PPIDs (NIH-PCT:20; MSD:1; both: 4). PDA segmentations were done by R1 in 91 eligible CTs (TCIA-PDA:42; MSD:49). Of these, corrections were made by R3 in 16 CTs (18%) (TCIA-PDA:4; MSD:12) [mean (standard deviation) Dice: 0.72(0.21) and 0.63(0.23) respectively].

Conclusion: Substantial quality gaps, sources of bias, and high proportion of CTs unsuitable for AI characterize the available limited PPIDs. Published studies on these PPIDs do not account for these quality gaps. We complement these PPIDs through post-hoc labels and segmentations for public release on the TCIA portal. Collaborative efforts leading to large, well-curated PPIDs supported by adequate documentation are critically needed to translate the promise of AI to clinical practice.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.pan.2021.03.016DOI Listing
August 2021

Automated radiomic analysis of CT images to predict likelihood of spontaneous passage of symptomatic renal stones.

Emerg Radiol 2021 Aug 1;28(4):781-788. Epub 2021 Mar 1.

Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.

Purpose: To evaluate the ability of a semi-automated radiomic analysis software in predicting the likelihood of spontaneous passage of urinary stones compared with manual measurements.

Methods: Symptomatic patients visiting the emergency department with suspected stones in either kidney or ureters who underwent a CT scan were included. Patients were followed for up to 6 months for the outcome of a trial of passage. Maximum stone diameters in axial and coronal images were measured manually. Stone length, width, height, max diameter, volume, the mean and standard deviation of the Hounsfield units, and morphologic features were also measured using automated radiomic analysis software. Multivariate models were developed using these data to predict subsequent spontaneous stone passage, with results expressed as the area under a receiver operating curve (AUC).

Results: One hundred eighty-four patients (69 females) with a median age of 56 years were included. Spontaneous stone passage occurred in 114 patients (62%). Univariate analysis demonstrated an AUC of 0.83 and 0.82 for the maximum stone diameter determined manually in the axial and coronal planes, respectively. Multivariate models demonstrated an AUC of 0.82 for a model including manual measurement of maximum stone diameter in axial and coronal planes. The same AUC was found for a model including automatic measurement of maximum height and diameter of the stone. Further addition of morphological parameters measured automatically did not increase AUC beyond 0.83.

Conclusion: The semi-automated radiomic analysis of urinary stones shows similar accuracy compared with manual measurements for predicting urinary stone passage. Further studies are needed to predict clinical impacts of reporting the likelihood of urinary stone passage and improving inter-observer variation using automatic radiomic analysis software.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10140-021-01915-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8477419PMC
August 2021

The feasibility of low iodine dynamic CT angiography with test bolus for evaluation of lower extremity peripheral artery disease.

Vascular 2021 Dec 17;29(6):927-937. Epub 2021 Jan 17.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Objective: This study aims to determine if low iodine dynamic computed tomography angiography performed after a fixed delay or test bolus acquisition demonstrates high concordance with clinical computed tomography angiography (using a routine amount of iodinated contrast) to display lower extremity peripheral arterial disease.

Methods: After informed consent, low iodine dynamic computed tomography angiography examination (using either a fixed delay or test bolus) using 50 ml of iodine contrast media was performed. A subsequent clinical computed tomography angiography using standard iodine dose (115 or 145 ml) served as the reference standard. A vascular radiologist reviewed dynamic and clinical computed tomography angiography images to categorize the lumen into "not opacified", "<50% stenosis", " 50 ̶70% stenosis", ">70% stenosis", and "occluded" for seven arterial segments in each lower extremity. Concordance between low iodine dynamic computed tomography angiography and the routine iodine reference standard was calculated. The clinical utility of 4D volume-rendered images was also evaluated.

Results: Sixty-eight patients (average age 66.1 ± 12.3 years, male; female = 49: 19) were enrolled, with 34 patients each undergoing low iodine dynamic computed tomography angiography using fixed delay and test bolus techniques, respectively. One patient assigned to the test bolus group did not undergo low iodine computed tomography angiography due to unavailable delayed time. The fixed delay was 13 s, with test bolus acquisition resulting in a mean variable delay prior to image acquisition of 19.5 s (range; 8-32 s). Run-off to the ankle was observed using low iodine dynamic computed tomography angiography following fixed delay and test bolus acquisition in 76.4% (26/34) and 100% (33/33) of patients, respectively ( = 0.005). Considering extremities with run-off to the ankle and without severe artifact, the concordance rate between low iodine dynamic computed tomography angiography and the routine iodine reference standard was 86.8% (310/357) using fixed delay and 97.9% (425/434) using test bolus ( < 0.001). 4D volume-rendered images using fixed delay and test bolus demonstrated asymmetric flow in 57.7% (15/26) and 58.1% (18/31) ( = 0.978) of patients, and collateral blood flow in 11.5% (3/26) and 22.6% (7/31) of patients ( = 0.319), respectively.

Conclusion: Low iodine dynamic computed tomography angiography with test bolus acquisition has a high concordance with routine peripheral computed tomography angiography performed with standard iodine dose, resulting in improved run-off to the ankle compared to dynamic computed tomography angiography performed after a fixed delay. This method is useful for minimizing iodine dose in patients at risk for contrast-induced nephropathy. 4D volume-rendered computed tomography angiography images provide useful dynamic information.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1708538120986304DOI Listing
December 2021

Low-dose CT image and projection dataset.

Med Phys 2021 Feb 16;48(2):902-911. Epub 2020 Dec 16.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Purpose: To describe a large, publicly available dataset comprising computed tomography (CT) projection data from patient exams, both at routine clinical doses and simulated lower doses.

Acquisition And Validation Methods: The library was developed under local ethics committee approval. Projection and image data from 299 clinically performed patient CT exams were archived for three types of clinical exams: noncontrast head CT scans acquired for acute cognitive or motor deficit, low-dose noncontrast chest scans acquired to screen high-risk patients for pulmonary nodules, and contrast-enhanced CT scans of the abdomen acquired to look for metastatic liver lesions. Scans were performed on CT systems from two different CT manufacturers using routine clinical protocols. Projection data were validated by reconstructing the data using several different reconstruction algorithms and through use of the data in the 2016 Low Dose CT Grand Challenge. Reduced dose projection data were simulated for each scan using a validated noise-insertion method. Radiologists marked location and diagnosis for detected pathologies. Reference truth was obtained from the patient medical record, either from histology or subsequent imaging.

Data Format And Usage Notes: Projection datasets were converted into the previously developed DICOM-CT-PD format, which is an extended DICOM format created to store CT projections and acquisition geometry in a nonproprietary format. Image data are stored in the standard DICOM image format and clinical data in a spreadsheet. Materials are provided to help investigators use the DICOM-CT-PD files, including a dictionary file, data reader, and user manual. The library is publicly available from The Cancer Imaging Archive (https://doi.org/10.7937/9npb-2637).

Potential Applications: This CT data library will facilitate the development and validation of new CT reconstruction and/or denoising algorithms, including those associated with machine learning or artificial intelligence. The provided clinical information allows evaluation of task-based diagnostic performance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/mp.14594DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7985836PMC
February 2021

Triple-Phase Computed Tomography May Replace Dual-Energy X-ray Absorptiometry Scan for Evaluation of Osteoporosis in Liver Transplant Candidates.

Liver Transpl 2021 02 4;27(3):341-348. Epub 2021 Mar 4.

Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN.

Assessment of bone density is an important part of liver transplantation (LT) evaluation for early identification and treatment of osteoporosis. Dual-energy X-ray absorptiometry (DXA) is currently the standard clinical test for osteoporosis; however, it may contribute to the appointment burden on LT candidates during the cumbersome evaluation process, and there are limitations affecting its accuracy. In this study, we evaluate the utility of biomechanical analysis of vertebral images obtained during dual-energy abdominal triple-phase computed tomography (TPCT) in diagnosing osteoporosis among LT candidates. We retrospectively reviewed cases evaluated for LT between January 2017 and March 2018. All patients who underwent TPCT within 3 months of DXA were included. The biomechanical computed tomography (BCT) analysis was performed at a centralized laboratory (O.N. Diagnostics, Berkeley, CA) by 2 trained analysts blinded to the DXA data. DXA-based osteoporosis was defined as a T score ≤-2.5 at the hip or spine. BCT-based osteoporosis was defined as vertebral strength ≤4500 N for women or ≤6500 N for men or trabecular volumetric bone mineral density ≤80 mg/cm . Comparative data were available for 91 patients who had complete data for both DXA and BCT: 31 women and 60 men, age 54 ± 11 years (mean ± standard deviation), mean body mass index 28 ± 6 kg/m . Using DXA as the clinical reference, sensitivity of BCT to detect DXA-defined osteoporosis was 83.3% (20/24 patients) and negative predictive value was 91.7%; specificity and positive predictive value were 65.7% and 46.5%, respectively. BCT analysis of vertebral images on triple-phase computed tomography, routinely obtained during transplant evaluation, can reliably rule out osteoporosis in LT candidates. Patients with suspicion of osteoporosis on TPCT may need further evaluation by DXA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/lt.25926DOI Listing
February 2021

Noise reduction in CT image using prior knowledge aware iterative denoising.

Phys Med Biol 2020 Oct 16. Epub 2020 Oct 16.

Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA, Rochester, UNITED STATES.

The clinical demand for low image noise often limits the slice thickness used in many CT applications. However, a thick-slice image is more susceptible to longitudinal partial volume effects, which can blur key anatomic structures and pathologies of interest. In this work, we develop a prior-knowledge-aware iterative denoising (PKAID) framework that utilizes spatial data redundancy in the slice increment direction to generate low-noise, thin-slice images, and demonstrate its application in non-contrast head CT exams. The proposed technique takes advantage of the low-noise of thicker images and exploits the structural similarity between the thick- and thin-slice images to reduce noise in the thin-slice image. Phantom data and patient cases (n=3) of head CT were used to assess performance of this method. Images were reconstructed at clinically-utilized slice thickness (5 mm) and thinner slice thickness (2 mm). PKAID was used to reduce image noise in 2 mm images using the 5 mm images as low-noise prior. Noise amplitude, noise power spectra (NPS), modulation transfer function (MTF), and slice sensitivity profiles (SSP) of images before/after denoising were analyzed. The NPS and MTF analysis showed that PKAID preserved noise texture and resolution of the original thin-slice image, while reducing noise to the level of thick-slice image. The SSP analysis showed that the slice thickness of the original thin-slice image was retained. Patient examples demonstrated that PKAID-processed, thin-slice images better delineated brain structures and key pathologies such as subdural hematoma compared to the clinical 5 mm images, while additionally reducing image noise. To test an alternative PKAID utilization for dose reduction, a head exam with 40% dose reduction was simulated using projection-domain noise insertion. The image of 5 mm slice thickness was then denoised using PKAID. The results showed that the PKAID-processed reduced-dose images maintained similar noise and image quality compared to the full-dose images.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6560/abc231DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8050138PMC
October 2020

Observer Performance for Detection of Pulmonary Nodules at Chest CT over a Large Range of Radiation Dose Levels.

Radiology 2020 12 29;297(3):699-707. Epub 2020 Sep 29.

From the Department of Radiology (J.G.F., D.L.L., A.M.G.S., R.M.L., D.B.W., R.S.K., V.S., L.Y., S.L., A.I., C.H.M.), Department of Physiology and Biomedical Engineering (D.R.H.), and Department of Health Science Research (M.P.J.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; and Department of Health Science Research, Mayo Clinic, Jacksonville, Fla (R.E.C.).

Background There is a wide variation in radiation dose levels that can be used with chest CT in order to detect indeterminate pulmonary nodules. Purpose To compare the performance of lower-radiation-dose chest CT with that of routine dose in the detection of indeterminate pulmonary nodules 5 mm or greater. Materials and Methods In this retrospective study, CT projection data from 83 routine-dose chest CT examinations performed in 83 patients (120 kV, 70 quality reference mAs [QRM]) were collected between November 2013 and April 2014. Reference indeterminate pulmonary nodules were identified by two nonreader thoracic radiologists. By using validated noise insertion, five lower-dose data sets were reconstructed with filtered back projection (FBP) or iterative reconstruction (IR; 30 QRM with FBP, 10 QRM with IR, 5 QRM with FBP, 5 QRM with IR, and 2.5 QRM with IR). Three thoracic radiologists circled pulmonary nodules, rating confidence that the nodule was a 5-mm-or-greater indeterminate pulmonary nodule, and graded image quality. Analysis was performed on a per-nodule basis by using jackknife alternative free-response receiver operating characteristic figure of merit (FOM) and noninferiority limit of -0.10. Results There were 66 indeterminate pulmonary nodules (mean size, 8.6 mm ± 3.4 [standard deviation]; 21 part-solid nodules) in 42 patients (mean age, 51 years ± 17; 21 men and 21 women). Compared with the FOM for routine-dose CT (size-specific dose estimate, 6.5 mGy ± 1.8; FOM, 0.86 [95% confidence interval: 0.80, 0.91]), FOM was noninferior for all lower-dose configurations except for 2.5 QRM with IR. The sensitivity for subsolid nodules at 70 QRM was 60% (range, 48%-72%) and was significantly worse at a dose of 5 QRM and lower, whether or not IR was used ( < .05). Diagnostic image quality decreased with decreasing dose ( < .001) and was better with IR at 5 QRM ( < .05). Conclusion CT images reconstructed at dose levels down to 10 quality reference mAs (size-specific dose estimate, 0.9 mGy) had noninferior performance compared with routine dose in depicting pulmonary nodules. Iterative reconstruction improved subjective image quality but not performance at low dose levels. © RSNA, 2020 . See also the editorial by White and Kazerooni in this issue.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1148/radiol.2020200969DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7706885PMC
December 2020

Clinical evaluation of a new adaptive iterative metal artifact reduction method in whole-body low-dose CT skeletal survey examinations.

Skeletal Radiol 2021 Jan 20;50(1):149-157. Epub 2020 Jul 20.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Objective: To evaluate a new adaptive iterative metal artifact reduction algorithm (AiMAR) in whole-body low-dose CT (WBLDCT) skeletal survey examinations.

Methods: Projection data were retrospectively obtained from 25 clinical WBLDCT skeletal survey patients, each with two types of metal implants. Images were reconstructed with bone and soft tissue kernels using four settings-original and AiMAR with strengths of 2, 4, and 5. All images were anonymized and randomized for a reader study, where three musculoskeletal radiologists independently determined the overall ranking of all series based on diagnostic quality, and local scoring of metal artifact and anatomy visualization for each implant. Quantitative image noise analysis was performed in areas close to the implants. Intraclass correlation coefficients (ICC) and Krippendorff's alpha were computed for inter-rater reliability.

Results: AiMAR 4 was ranked the highest for 64.3% of the series across eight types of implants. For local scoring task, AiMAR 4 showed better metal artifact and anatomy visualization than the original and AiMAR 2. AiMAR 4 was comparable in anatomy visualization but inferior to AiMAR 5 in metal artifact scores. AiMAR 4 led to 56.3% noise reduction around the implant areas compared with the original images, and AiMAR 5 68.1% but also resulted in anatomy blurring in 40% of the implants. ICC and Krippendorff's alpha revealed at least substantial reliability in the local scores among the readers.

Conclusions: AiMAR was evaluated in WBLDCT skeletal surveys. AiMAR 4 demonstrated the highest overall quality ranking and improved local scores with noise reduction around implant areas.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00256-020-03547-0DOI Listing
January 2021

Deep-learning-based model observer for a lung nodule detection task in computed tomography.

J Med Imaging (Bellingham) 2020 Jul 30;7(4):042807. Epub 2020 Jun 30.

Mayo Clinic, Department of Radiology, Rochester, Minnesota, United States.

Task-based image quality assessment using model observers (MOs) is an effective approach to radiation dose and scanning protocol optimization in computed tomography (CT) imaging, once the correlation between MOs and radiologists can be established in well-defined clinically relevant tasks. Conventional MO studies were typically simplified to detection, classification, or localization tasks using tissue-mimicking phantoms, as traditional MOs cannot be readily used in complex anatomical background. However, anatomical variability can affect human diagnostic performance. To address this challenge, we developed a deep-learning-based MO (DL-MO) for localization tasks and validated in a lung nodule detection task, using previously validated projection-based lesion-/noise-insertion techniques. The DL-MO performance was compared with 4 radiologist readers over 12 experimental conditions, involving varying radiation dose levels, nodule sizes, nodule types, and reconstruction types. Each condition consisted of 100 trials (i.e., 30 images per trial) generated from a patient cohort of 50 cases. DL-MO was trained using small image volume-of-interests extracted across the entire volume of training cases. For each testing trial, the nodule searching of DL-MO was confined to a 3-mm thick volume to improve computational efficiency, and radiologist readers were tasked to review the entire volume. A strong correlation between DL-MO and human readers was observed (Pearson's correlation coefficient: 0.980 with a 95% confidence interval of [0.924, 0.994]). The averaged performance bias between DL-MO and human readers was 0.57%. The experimental results indicated the potential of using the proposed DL-MO for diagnostic image quality assessment in realistic chest CT tasks.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/1.JMI.7.4.042807DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7324744PMC
July 2020

Fat quantification of the rotator cuff musculature using dual-energy CT-A pilot study.

Eur J Radiol 2020 Sep 23;130:109145. Epub 2020 Jun 23.

Department of Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, United States. Electronic address:

Purpose: To assess the ability of dual-energy CT (DECT) as a novel technique to quantify the degree of rotator cuff fat degeneration.

Method: Clinically indicated shoulder CT exams for evaluation of osteoarthritis, rotator cuff arthropathy, pain or instability, or preoperative planning were acquired using dual-source CT systems. Rotator cuff DECT fat fraction after material decomposition was calculated off the sagittal image. Fat fractions were also assessed using CT numbers from dual energy virtual monochromatic images (70 keV) and single-energy CT (SECT) images (100 kV). Visual subjective Goutallier scores of the rotator cuff muscles were used as the reference standard.

Results: 12 shoulders from 10 patients were analyzed, with bilateral shoulders evaluated in two patients (mean age 69 years (range 19-97)). Three patients were male and seven were female, with mean BMI of 32 (range 26-41). Mean fat fraction of the teres major and subcutaneous fat were, 2.9 % ± 4.0 % and 99.5 % ± 2.6 %, respectively, rendering these as reliable internal standards for 0% and 100 % fat. Mean DECT fat fractions of the rotator cuff were compared to Goutallier scores, revealing a high strength of rank correlation: ρ = 0.92, p < 0.0001. Mean fat fraction assessed with CT numbers also revealed high strengths of linear associations: ρ = 0.83, p < 0.0001 and ρ = 0.82, p < 0.0001, for DECT 70 keV and SECT 100 kV, respectively.

Conclusions: DECT direct fat fraction after material decomposition presents a novel approach to quantitative assessment of fatty degeneration, which has excellent correlation with clinically accepted standards.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejrad.2020.109145DOI Listing
September 2020

Benefits of iterative metal artifact reduction and dual-energy CT towards mitigating artifact in the setting of total shoulder prostheses.

Skeletal Radiol 2021 Jan 29;50(1):51-58. Epub 2020 Jun 29.

Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA.

Objective: To determine the utility of iterative metal artifact reduction and 130 keV dual-energy virtual monoenergetic images to improve bone and soft tissue visualization in CT scans affected by metal artifacts.

Material And Methods: Thirteen females and 6 males with a history of total shoulder prosthesis who underwent dual-energy shoulder CT were included. Four sets of images were reconstructed for each patient: (1) original polychromatic kV images reconstructed with weighted filtered back projection; (2) polychromatic kV images with iterative metal artifact reduction; (3) 130 keV dual-energy virtual monoenergetic; (4) combined iterative metal artifact reduction and 130 keV dual-energy virtual monoenergetic. Three readers blindly reviewed all image sets and graded the extent of artifact and image quality.

Results: Mean artifact score and median overall image quality score were better in 130 keV dual-energy virtual monoenergetic with iterative metal artifact reduction compared with those in original polychromatic kV images (3.02 vs 4.28, P < 0.001 and 3.00 vs 4.33, P < 0.001, respectively). The median difference in CT numbers between regions affected by artifacts and normal regions was lowest in 130 keV dual-energy virtual monoenergetic with iterative metal artifact reduction compared with that in original polychromatic kV images (72.28 vs 252.08, P < 0.001 for bony regions and 15.09 vs 324.38, P < 0.001 for soft tissue).

Conclusion: In patients with metal artifacts due to shoulder replacement surgery, the use of dual-energy monoenergetic images and iterative metal artifact reduction reconstruction significantly improves both subjective and objective indicators of image quality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00256-020-03528-3DOI Listing
January 2021

Simultaneous Dual-Contrast Imaging of Small Bowel With Iodine and Bismuth Using Photon-Counting-Detector Computed Tomography: A Feasibility Animal Study.

Invest Radiol 2020 10;55(10):688-694

From the Department of Radiology, Mayo Clinic, Rochester, MN.

Objectives: Dual-energy and multienergy computed tomography (DECT/MECT) has the potential to simultaneously visualize two contrast agents in the small bowel: arterial enhancement of iodine in the bowel wall and enteric enhancement of bismuth in the bowel lumen. The purpose of this study was to explore its feasibility in a swine study using a research whole-body photon-counting-detector (PCD) computed tomography (CT) system.

Materials And Methods: A phantom study was initially performed to evaluate the quantification accuracy of iodine and bismuth separation from a single PCD-CT scan, which also served as the calibration reference for material decomposition of in vivo swine PCD-CT data. In the animal study, a test bolus scan was first performed to determine the time-attenuation curve for the arterial enhancement, based on which the timing of the PCD-CT dual-contrast scan was determined. A 600 mL homogeneous bismuth-saline solution (180 mL Pepto-Bismol + 420 mL normal saline) was orally administered to the pig using esophageal intubation. Approximately 1 hour after bismuth administration, 40 mL iodine contrast (Omnipaque 350, 5 mL/s) was injected intravenously. A PCD-CT scan was performed 13 seconds after the initiation of the contrast injection to simultaneously capture the arterial enhancement of iodine and the enteric enhancement of bismuth. To provide optimal material separation and quantification, all PCD-CT scans in both phantom and animal studies were operated at 140 kV with 4 energy thresholds of 25, 50, 75, and 90 keV.

Results: Using a generic image-based material decomposition method, the iodine and bismuth samples were successfully delineated and quantified in the phantom images with a root-mean-square-error of 1.32 mg/mL in iodine measurement and 0.64 mg/mL in bismuth measurement. In the pig study, the enhancing bowel wall containing iodine and the small bowel loop containing bismuth were not differentiable in the original PCD-CT images. However, they were clearly distinctive from each other in the iodine- and bismuth-specific images after material decomposition, as reviewed by an abdominal radiologist. In addition, quantitative analysis showed that the misclassification between the two contrast materials was less than 1.0 mg/mL.

Conclusions: Our study demonstrated the feasibility of simultaneous imaging of iodine and bismuth in small bowel of swine using PCD-CT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/RLI.0000000000000687DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7808340PMC
October 2020

Panenteric capsule endoscopy versus ileocolonoscopy plus magnetic resonance enterography in Crohn's disease: a multicentre, prospective study.

BMJ Open Gastroenterol 2020 06;7(1)

Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Introduction: Crohn's disease diagnosis and monitoring remains a great clinical challenge and often requires multiple testing modalities. Assessing Crohn's disease activity in the entire gastrointestinal (GI) tract using a panenteric capsule endoscopy (CE) system could be used as an alternative to colonoscopy and cross-sectional imaging. This study assessed the accuracy and safety of panenteric CE in Crohn's disease as compared with ileocolonoscopy (IC) and/or magnetic resonance enterography (MRE).

Methods: A prospective, multicentre study was performed in subjects with established Crohn's disease. Individuals with proven small bowel patency underwent a standardised bowel preparation, followed by CE ingestion and IC either the same or following day. MRE, IC, and CE interpretations were performed by blinded central readers using validated scoring systems. The primary endpoint was the overall sensitivity of CE vs MRE and/or IC in Crohn's disease subjects.

Results: Study enrolment included 158 subjects from 21 sites in the USA, Austria, and Israel. Of those, 99 were included in the analysis. Imaging modality scores indicated none to mild inflammation in the proximal small bowel and colon, but discrepant levels of inflammation in the terminal ileum. Overall sensitivity for active enteric inflammation (CE vs MRE and/or IC) was 94% vs 100% (p=0.125) and specificity was 74% vs 22% (p=0.001). Sensitivity of CE was superior to MRE for enteric inflammation in the proximal small bowel (97% vs 71%, p=0.021), and similar to MRE and/or IC in the terminal ileum and colon (p=0.500-0.625). There were seven serious adverse advents of which three were related to the CE device.

Conclusion: Panenteric CE is a reliable tool for assessing Crohn's disease mucosal activity and extent compared with more invasive methods. This study demonstrates high performance of the panenteric CE as compared to MRE and/or IC without the need for multiple tests in non-stricturing Crohn's disease.

Trial Registration Number: ClinicalTrials.gov NCT03241368.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/bmjgast-2019-000365DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7282309PMC
June 2020

Multiphase Computed Tomographic Enterography: Diagnostic Yield and Efficacy in Patients With Suspected Small Bowel Bleeding.

Mayo Clin Proc Innov Qual Outcomes 2019 Dec 22;3(4):438-447. Epub 2019 Nov 22.

Division of Abdominal Imaging, Mayo Clinic, Rochester, MN.

Objective: To estimate the diagnostic yield and efficacy of multiphase computed tomographic enterography (mpCTE) for suspected small bowel bleeding in routine clinical practice.

Patients And Methods: All mpCTEs performed between January 1, 2006, and December 31, 2014, for suspected small bowel bleeding were included and classified by a gastroenterologist and an abdominal radiologist. The reference standard for a definitive diagnosis was balloon-assisted enteroscopic, angiographic, surgical, or pathologic results. Overall and lesion-specific diagnostic yield (DY), sensitivity, and positive predictive value were calculated. The relationship of mpCTE diagnosis and continued bleeding or iron supplementation was examined using logistic regression in patients with at least 1 year of follow-up.

Results: We identified 1087 patients who had an initial mpCTE indication of small bowel bleeding. The overall DY was 31.6% (344 of 1087 patients; 95% CI, 29.0%-35.0%), higher for an indication of small bowel bleeding that was overt or occult with heme-positive stool vs occult with only iron-deficiency anemia (DY, 35.0% [170 of 486] and 35.3% [66 of 187] vs 26.1% [108 of 414]; =.004 and =.02, respectively). The highest sensitivity and positive predictive value were for small bowel masses (90.2% [55 of 61] and 98.2% [55 of 56], respectively). Higher risk of future bleeding and iron supplementation was seen with a negative result on mpCTE (odds ratio [OR], 1.91; 95% CI, 1.28-2.86), lack of surgical intervention (OR, 4.37; 95% CI, 2.31-8.29), or discrepant balloon-assisted enteroscopic findings (OR, 2.50; 95% CI, 1.03-6.09).

Conclusion: Multiphase computed tomographic enterography has a higher rate of detection in patients with overt bleeding or heme-positive stool. The procedure provides actionable targets for further intervention and leads to substantially reduced rates of rebleeding in long-term follow-up.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.mayocpiqo.2019.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6978607PMC
December 2019

Image quality in abdominal CT using an iodine contrast reduction algorithm employing patient size and weight and low kV CT technique.

Acta Radiol 2020 Sep 27;61(9):1186-1195. Epub 2020 Jan 27.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Background: Low tube potential-high tube current computed tomography (CT) imaging allows reduction in iodine-based contrast dose and may extend the benefit of routine contrast-enhanced CT exams to patients at risk of nephrotoxicity.

Purpose: To determine the ability of an iodine contrast reduction algorithm to maintain diagnostic image quality for contrast-enhanced abdominal CT.

Material And Methods: CT exams with iodine contrast reduction were prescribed for patients at risk for renal dysfunction. The iodine contrast reduction algorithm combines weight-based contrast volume reduction with patient width-based low tube potential selection and bolus-tracking. Control exams with routine iodine dose were selected based on weight, width, and scan protocol. Three radiologists evaluated image quality and diagnostic confidence using a 4-point scale (<2 acceptable). Another radiologist assessed contrast reduction indications and measured portal vein and liver contrast-to-noise ratios.

Results: Forty-six contrast reduction algorithm and control exams were compared (mean creatinine 1.6 vs. 1.2 mg/dL, ≤0.0001). Thirty-nine contrast reduction patients had an eGFR <60 mL/min/1.73m and 15 had single or transplanted kidney. Mean iodine contrast dose was lower in the contrast reduction group (20.9 vs. 39.4 g/mL, <0.0001). Diagnostic confidence was rated as acceptable in 95% (131/138) of contrast reduction and 100% of control exams (1.18-1.28 vs. 1.02-1.13, respectively; >0.06). Liver attenuation and contrast-to-noise ratio (CNR) were similar (=0.08), but portal vein attenuation and CNR were lower with contrast-reduction (mean 176 vs. 198 HU, =0.02; 13 vs. 16, =0.0002).

Conclusion: This size-based contrast reduction algorithm using low kV and bolus tracking reduced iodine contrast dose by 50%, while achieving acceptable image quality in 95% of exams.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/0284185119898655DOI Listing
September 2020

Computed tomography and magnetic resonance enterography protocols and techniques: survey of the Society of Abdominal Radiology Crohn's Disease Disease-Focused Panel.

Abdom Radiol (NY) 2020 04;45(4):1011-1017

Department of Radiology, University of California, San Francisco, USA.

Purpose: To survey Society of Abdominal Radiology Crohn's Disease (CD) Disease-Focused Panel (DFP) members to understand state-of-the-art CT/MR enterography (CTE/MRE) protocols and variability between institutions.

Methods: This study was determined by an institutional review board to be "exempt" research. The survey consisted of 70 questions about CTE/MRE patient preparation, administration of contrast materials, imaging techniques, and other protocol details. The survey was administered to DFP members using SurveyMonkey® (Surveymonkey.com). Descriptive statistical analyses were performed.

Results: Responses were received from 16 DFP institutions (3 non-USA, 2 pediatric); 15 (94%) were academic/university-based. 10 (63%) Institutions image most CD patients with MRE; 4 (25%) use CTE and MRE equally. Hypoperistaltic medication is given for MRE at 13 (81%) institutions versus only 2 (13%) institutions for CTE. Most institutions have a technologist or nurse monitor oral contrast material drinking (n = 12 for CTE, 75%; n = 11 for MRE, 69%). 2 (13%) institutions use only dual-energy capable scanners for CTE, while 9 (56%) use either a single-energy or dual-energy scanner based on availability. Axial CTE images are reconstructed at 2-3 mm thickness at 8 (50%) institutions, > 3 mm at 5 (31%), and < 2 mm at 3 (19%) institutions. 13 (81%) institutions perform MRE on either 1.5 or 3T scanners without preference. All institutions perform MRE multiphase postcontrast imaging (median = 4 phases), ranging from 20 to 600 s after contrast material injection.

Conclusion: CTE and MRE protocol knowledge from DFP institutions can help radiology practices optimize/standardize protocols, potentially improving image quality and patient outcomes, permitting objective comparisons between examinations, and facilitating research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00261-020-02407-8DOI Listing
April 2020
-->