Publications by authors named "Aya Kamaya"

123 Publications

Improving plane wave ultrasound imaging through real-time beamformation across multiple arrays.

Sci Rep 2022 Aug 4;12(1):13386. Epub 2022 Aug 4.

Stanford University, Palo Alto, CA, USA.

Ultrasound imaging is a widely used diagnostic tool but has limitations in the imaging of deep lesions or obese patients where the large depth to aperture size ratio (f-number) reduces image quality. Reducing the f-number can improve image quality, and in this work, we combined three commercial arrays to create a large imaging aperture of 100 mm and 384 elements. To maintain the frame rate given the large number of elements, plane wave imaging was implemented with all three arrays transmitting a coherent wavefront. On wire targets at a depth of 100 mm, the lateral resolution is significantly improved; the lateral resolution was 1.27 mm with one array (1/3 of the aperture) and 0.37 mm with the full aperture. After creating virtual receiving elements to fill the inter-array gaps, an autoregressive filter reduced the grating lobes originating from the inter-array gaps by - 5.2 dB. On a calibrated commercial phantom, the extended field-of-view and improved spatial resolution were verified. The large aperture facilitates aberration correction using a singular value decomposition-based beamformer. Finally, after approval of the Stanford Institutional Review Board, the three-array configuration was applied in imaging the liver of a volunteer, validating the potential for enhanced resolution.
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http://dx.doi.org/10.1038/s41598-022-16961-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9352764PMC
August 2022

Comparative Study of Raw Ultrasound Data Representations in Deep Learning to Classify Hepatic Steatosis.

Ultrasound Med Biol 2022 Jul 29. Epub 2022 Jul 29.

Department of Radiology, Stanford University, Stanford, California, USA.

Adiposity accumulation in the liver is an early-stage indicator of non-alcoholic fatty liver disease. Analysis of ultrasound (US) backscatter echoes from liver parenchyma with deep learning (DL) may offer an affordable alternative for hepatic steatosis staging. The aim of this work was to compare DL classification scores for liver steatosis using different data representations constructed from raw US data. Steatosis in N = 31 patients with confirmed or suspected non-alcoholic fatty liver disease was stratified based on fat-fraction cutoff values using magnetic resonance imaging as a reference standard. US radiofrequency (RF) frames (raw data) and clinical B-mode images were acquired. Intermediate image formation stages were modeled from RF data. Power spectrum representations and phase representations were also calculated. Co-registered patches were used to independently train 1-, 2- and 3-D convolutional neural networks (CNNs), and classifications scores were compared with cross-validation. There were 67,800 patches available for 2-D/3-D classification and 1,830,600 patches for 1-D classification. The results were also compared with radiologist B-mode annotations and quantitative ultrasound (QUS) metrics. Patch classification scores (area under the receiver operating characteristic curve [AUROC]) revealed significant reductions along successive stages of the image formation process (p < 0.001). Patient AUROCs were 0.994 for RF data and 0.938 for clinical B-mode images. For all image formation stages, 2-D CNNs revealed higher patch and patient AUROCs than 1-D CNNs. CNNs trained with power spectrum representations converged faster than those trained with RF data. Phase information, which is usually discarded in the image formation process, provided a patient AUROC of 0.988. DL models trained with RF and power spectrum data (AUROC = 0.998) provided higher scores than conventional QUS metrics and multiparametric combinations thereof (AUROC = 0.986). Radiologist annotations indicated lower hepatic steatosis classification accuracies (Acc = 0.914) with respect to magnetic resonance imaging proton density fat fraction that DL models (Acc = 0.989). Access to raw ultrasound data combined with artificial intelligence techniques may offer superior opportunities for quantitative tissue diagnostics than conventional sonographic images.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2022.05.031DOI Listing
July 2022

Clinical and ultrasound features of dermoid-associated adnexal torsion.

Abdom Radiol (NY) 2022 Jul 9. Epub 2022 Jul 9.

Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, H1307, Stanford, CA, 94305, USA.

Purpose: To determine the clinical and ultrasound features of dermoid-associated adnexal torsion.

Methods: Forty-four patients with at least one dermoid and ultrasound ≤ 30 days of surgery were retrospectively reviewed by three radiologists. Ultrasound and clinical findings were compared to intra-operative findings using Fisher's exact test or Mann-Whitney test with p < 0.05 to determine statistical significance.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.Correct. No edit RESULTS: Twenty patients had torsion, while 24 patients did not. Patients with dermoid-associated torsion were more likely to present to emergency department (ED) (100% vs 13%; p < 0.001) and have acute unilateral pelvic pain (100% vs 42%; p < 0.001). On ultrasound, patients with torsion had larger dermoids (median largest dimension 9.0 cm (IQR 7.7-11.1) vs 6.0 cm (IQR 4.4-7.5); p < 0.001), displaced dermoid anterior or superior to the uterus (59% vs 21%; p = 0.016), and ipsilateral adnexal fluid (41% vs 4%; p = 0.003). Displaced dermoid and ipsilateral adnexal fluid had substantial (kappa = 0.72) and moderate inter-rater agreement (kappa = 0.49), respectively. The combination of ED presentation and each statistically significant ultrasound feature (dermoid size ≥ 5.0 cm, displaced dermoid, and ipsilateral adnexal fluid) yielded high specificity and positive predictive value (ranging from 93-100% to 92-100%, respectively). The combination of ED presentation and dermoid size ≥ 5.0 cm yielded the highest sensitivity, negative predicative value, and accuracy (100%, 100%, and 96%, respectively).Please check and confirm whether the edit made to the article title is in order.Looks great. No edits. Thank you!

Conclusion: Although the diagnosis of adnexal torsion in the presence of an ovarian dermoid is traditionally challenging, the combination of ED presentation and ultrasound features increase diagnostic confidence of dermoid-associated adnexal torsion.
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http://dx.doi.org/10.1007/s00261-022-03601-6DOI Listing
July 2022

Management of Incidentally Detected Gallbladder Polyps: Society of Radiologists in Ultrasound Consensus Conference Recommendations.

Radiology 2022 Jul 5:213079. Epub 2022 Jul 5.

From the Departments of Radiology (A.K.), Pathology (D.B.B.), Medicine (W.G.P.), and Ultrasound (X.Y.), Stanford University School of Medicine, Stanford Hospital and Clinics, 300 Pasteur Dr, H1307, Stanford, CA 94305; Department of Radiology, University of Alberta Hospital, Edmonton, Alberta, Canada (C.F., A.J.W.); Department of Gastroenterology, Kaiser Permanente Northern California, Oakland, Calif (J.L.S.); Departments of Radiology (D.T.F.) and Surgical Oncology (M.R.P.), University of Texas Southwestern Medical Center, Dallas, Tex; Department of Surgery, MedStar Georgetown University Hospital, Washington, DC (Y.A.); Department of Radiology, University of California Davis Medical Center, Sacramento, Calif (M.T.C.); Department of Radiology, Mayo Clinic Scottsdale, Phoenix, Ariz (N.D.); Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, Ill (H.G.); Department of Radiology, Sidney Kimmel Medical College, Thomas Jefferson University, Cherry Hill, NJ (S.K.R.); Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pa (M.E.T.); Joint Pathology Center, Silver Spring, Md (Y.Z.); and Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (W.D.M.).

Gallbladder polyps (also known as polypoid lesions of the gallbladder) are a common incidental finding. The vast majority of gallbladder polyps smaller than 10 mm are not true neoplastic polyps but are benign cholesterol polyps with no inherent risk of malignancy. In addition, recent studies have shown that the overall risk of gallbladder cancer is not increased in patients with small gallbladder polyps, calling into question the rationale for frequent and prolonged follow-up of these common lesions. In 2021, a Society of Radiologists in Ultrasound, or SRU, consensus conference was convened to provide recommendations for the management of incidentally detected gallbladder polyps at US. See also the editorial by Sidhu and Rafailidis in this issue.
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http://dx.doi.org/10.1148/radiol.213079DOI Listing
July 2022

Interobserver agreement between eight observers using IOTA simple rules and O-RADS lexicon descriptors for adnexal masses.

Abdom Radiol (NY) 2022 Jun 28. Epub 2022 Jun 28.

Department of Radiology, Stanford Hospital and Clinics, Stanford, CA, USA.

Purpose: To evaluate interobserver agreement in assigning imaging features and classifying adnexal masses using the IOTA simple rules versus O-RADS lexicon and identify causes of discrepancy.

Methods: Pelvic ultrasound (US) examinations in 114 women with 118 adnexal masses were evaluated by eight radiologists blinded to the final diagnosis (4 attendings and 4 fellows) using IOTA simple rules and O-RADS lexicon. Each feature category was analyzed for interobserver agreement using intraclass correlation coefficient (ICC) for ordinal variables and free marginal kappa for nominal variables. The two-tailed significance level (a) was set at 0.05.

Results: For IOTA simple rules, interobserver agreement was almost perfect for three malignant lesion categories (M2-4) and substantial for the remaining two (M1, M5) with k-values of 0.80-0.82 and 0.68-0.69, respectively. Interobserver agreement was almost perfect for two benign feature categories (B2, B3), substantial for two (B4, B5) and moderate for one (B1) with k-values of 0.81-0.90, 0.69-0.70 and 0.60, respectively. For O-RADS, interobserver agreement was almost perfect for two out of ten feature categories (ascites and peritoneal nodules) with k-values of 0.89 and 0.97. Interobserver agreement ranged from fair to substantial for the remaining eight feature categories with k-values of 0.39-0.61. Fellows and attendings had ICC values of 0.725 and 0.517, respectively.

Conclusion: O-RADS had variable interobserver agreement with overall good agreement. IOTA simple rules had more uniform interobserver agreement with overall excellent agreement. Greater reader experience did not improve interobserver agreement with O-RADS.
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http://dx.doi.org/10.1007/s00261-022-03580-8DOI Listing
June 2022

Patient-Friendly Summary of the ACR Appropriateness Criteria Crohn Disease-Child.

J Am Coll Radiol 2022 Jun 13. Epub 2022 Jun 13.

interim Chief, Body Imaging Division, Director of Ultrasound, and Associate Director, Body Imagin Fellowship, Department of Radiology, Stanford University School of Medicine, Stanford, California. Electronic address:

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http://dx.doi.org/10.1016/j.jacr.2022.05.010DOI Listing
June 2022

Nyquist sampling theorem and Bosniak classification, version 2019: effect of thin axial sections on categorization and agreement.

Eur Radiol 2022 Jun 15. Epub 2022 Jun 15.

Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Room H-1307 and Room S-072, Stanford, CA, 94305, USA.

Objective: To determine if CT axial images reconstructed at current standard of care (SOC; 2.5-3 mm) or thin (≤ 1 mm) sections affect categorization and inter-rater agreement of cystic renal masses assessed with Bosniak classification, version 2019.

Methods: In this retrospective single-center study, 3 abdominal radiologists reviewed 131 consecutive cystic renal masses from 100 patients performed with CT renal mass protocol from 2015 to 2021. Images were reviewed in two sessions: first with SOC and then the addition of thin sections. Individual and overall categorizations are reported, latter of which is based on majority opinion with 3-way discrepancies resolved by a fourth reader. Major categorization changes were defined as differences between classes I-II, IIF, or III-IV.

Results: Thin sections led to a statistically significant major category change with class II for all readers individually (p = 0.004-0.041; McNemar test), upgrading 10-17% of class II masses, most commonly to class IIF followed by III. Modal reason for upgrades was due to identification of additional septa followed by larger measurement of enhancing features. Masses categorized as class I, III, or IV on SOC sections were unaffected, as were identification of protrusions. Inter-rater agreements using weighted Cohen's kappa were 0.679 for SOC and 0.691 for thin sections (both substantial).

Conclusion: Thin axial sections upgraded up to one in six class II masses to IIF or III through identification of additional septa or larger feature. Other classes, including III-IV, were unaffected. Inter-rater agreements were substantial regardless of section thickness.

Key Points: • Thin axial sections (≤ 1 mm) compared to standard of care sections (2.5-3 mm) led to identification of additional septa but did not affect identification of protrusions. • Thin axial sections (≤ 1 mm) compared to standard of care sections (2.5-3 mm) can upgrade a small proportion of cystic renal masses from class II to IIF or III when applying Bosniak classification, version 2019. • Inter-rater agreements were substantial regardless of section thickness.
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http://dx.doi.org/10.1007/s00330-022-08876-3DOI Listing
June 2022

Outcomes of LI-RADS US-2 Subthreshold Observations Detected on Surveillance Ultrasound.

AJR Am J Roentgenol 2022 Aug 10:1-10. Epub 2022 Aug 10.

Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, Rm H-1307, Stanford, CA 94305.

Ultrasound LI-RADS version 2017 recommends that patients with US-2 subthreshold observations undergo repeat surveillance ultrasound in 3-6 months and return to routine surveillance if the observation shows no growth for 2 years. However, outcomes of US-2 observations are unknown. The purpose of this article was to determine imaging outcomes of US-2 observations detected on surveillance ultrasound examinations. This retrospective study included 175 patients (median age, 59 years; 70 women, 105 men) at high risk for hepatocellular carcinoma (HCC) with US-2 observations (i.e., subcentimeter observations) on surveillance ultrasound. Observations were classified on follow-up ultrasound performed 2 or more years later as showing no correlate, stable (if remaining subcentimeter), or progressed (if measuring ≥ 10 mm, meeting US-3 criteria). Observations were classified on follow-up multiphasic CT or MRI (stratified as < 2-year vs ≥ 2-year follow-up) as showing no correlate or, if showing a correlate, using CT/MRI LI-RADS version 2018. A total of 111 patients had follow-up ultrasound after 2 or more years and 106 had follow-up CT or MRI (79 before 2 years, 27 after 2 years). On the basis of final follow-up examinations, 173/175 observations were stable on follow-up ultrasound 2 or more years later ( = 68); showed no correlate on follow-up ultrasound, CT, or MRI ( = 88); or were classified as LR-1 or LR-2 on CT or MRI ( = 17). The remaining 2/175 observations were LR-3 on CT or MRI. No observations progressed to US-3 on follow-up ultrasound or were classified as LR-4 or greater on CT or MRI. A correlate was observed in 25 of the 106 follow-up CT or MRI examinations (LR-1 or LR-2 in 23; LR-3 in two). Eight patients developed HCC at a median of 2.0 years after initial US-2 observation detection; all HCCs were in separate locations from the baseline observations and were preceded by a surveillance ultrasound that could not reidentify the baseline observation. In three patients who underwent liver transplant, the explant showed no dysplastic nodule or HCC. US-2 subthreshold observations are unlikely to progress or become HCC and commonly have no correlate on follow-up imaging. Because of the low progression rate of US-2 subthreshold observations, it is unclear if an extended period of intensive surveillance, as recommended by multiple professional societies, is warranted.
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http://dx.doi.org/10.2214/AJR.22.27812DOI Listing
August 2022

Diagnostic Performance of the Ovarian-Adnexal Reporting and Data System (O-RADS) Ultrasound Risk Score in Women in the United States.

JAMA Netw Open 2022 06 1;5(6):e2216370. Epub 2022 Jun 1.

University of Wisconsin-Madison, Madison.

Importance: The American College of Radiology (ACR) Ovarian-Adnexal Reporting and Data System (O-RADS) ultrasound (US) risk scoring system has been studied in a selected population of women referred for suspected or known adnexal lesions. This population has a higher frequency of malignant neoplasms than women presenting to radiology departments for pelvic ultrasonography for a variety of indications, potentially impacting the diagnostic performance of the risk scoring system.

Objective: To evaluate the risk of malignant neoplasm and diagnostic performance of O-RADS US risk scoring system in a multi-institutional, nonselected cohort.

Design, Setting, And Participants: This multi-institutional cohort study included a population of nonselected women in the United States who presented to radiology departments for routine pelvic ultrasonography between 2011 and 2014, with pathology confirmation imaging follow up or 2 years of clinical follow up.

Exposure: Analysis of 1014 adnexal lesions using the O-RADS US risk stratification system.

Main Outcomes And Measures: Frequency of ovarian cancer and diagnostic performance of the O-RADS US risk stratification system.

Results: This study included 913 women with 1014 adnexal lesions. The mean (SD) age of the patients was 42.4 (13.9 years), and 674 of 913 (73.8%) were premenopausal. The overall frequency of malignant neoplasm was 8.4% (85 of 1014 adnexal lesions). The frequency of malignant neoplasm for O-RADS US 2 was 0.5% (3 of 657 lesions; <1% expected); O-RADS US 3, 4.5% (5 of 112 lesions; <10% expected); O-RADS US 4, 11.6% (18 of 155; 10%-50% expected); and O-RADS 5, 65.6% (59 of 90 lesions; >50% expected). O-RADS US 4 was the optimum cutoff for diagnosing cancer with sensitivity of 90.6% (95% CI, 82.3%-95.9%), specificity of 81.9% (95% CI, 79.3%-84.3%), positive predictive value of 31.4% (95% CI, 25.7%-37.7%) and negative predictive value of 99.0% (95% CI, 98.0%-99.6%).

Conclusions And Relevance: In this cohort study of a nonselected patient population, the O-RADS US risk stratification system performed within the expected range as published by the ACR O-RADS US committee. The frequency of malignant neoplasm was at the lower end of the published range, partially because of the lower prevalence of cancer in a nonselected population. However, a high negative predictive value was maintained, and when a lesion can be classified as an O-RADS US 2, the risk of cancer is low, which is reassuring for both clinician and patient.
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http://dx.doi.org/10.1001/jamanetworkopen.2022.16370DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9185186PMC
June 2022

Acing the Fundamentals of Radiology: An Online Series for Medical Students and Interns.

J Comput Assist Tomogr 2022 Jul-Aug 01;46(4):614-620. Epub 2022 Apr 8.

Department of Abdominal Imaging, University of Texas MD Anderson Cancer Center, Houston, TX.

Purpose: The current undergraduate radiology education predominantly integrates radiology with other disciplines during preclerkship years and is often taught by nonradiologists. Early exposure to radiology and profound understanding of scientific fundamentals of imaging modalities and techniques are essential for a better understanding and interest in the specialty. Furthermore, the COVID-19 pandemic-related impact on in-person medical education aggravated the need for alternative virtual teaching initiatives to provide essential knowledge to medical students.

Methods: The authors designed an online 7-session course on the principles of imaging modalities for medical students and fresh graduates in the United States and abroad. The course was delivered online and taught by radiologists from different US institutions. Pretests and posttests were delivered before and after each session, respectively, to assess change in knowledge. At the end of the course, a survey was distributed among students to collect their assessment and feedback.

Results: A total of 162 students and interns initially enrolled in the program by completing a sign-up interest form. An average of 65 participants attended each live session, with the highest attendance being 93 live attendees. An average of 44 attendees completed both the pretest and posttest for each session. There was a statistically significant increase in posttest scores compared with pretest scores ( P < 0.01) for each session; on average, the posttest scores were 48% higher than the pretest scores. A total of 84 participants answered the end-of-course survey. A total of 11% of the respondents described themselves as first year, 17% as second year, 18% as third year, 21% as fourth year, and 33% as "other." Attendees were enrolled in medical schools across 21 different countries with 35% of the respondents studying medicine in the United States. More than 76% of the respondents stated that they "strongly agree" that the program increased their understanding of radiology, increased their interest in radiology, and would be useful in their clinical practice in the future. Eighty-three percent of the respondents stated that they "strongly agree" that "this course was a worthwhile experience." Particularly, more than 84% of the respondents stated that among the most important components in enhancing their understanding of radiology were "the interpretation of normal imaging" and "interpretation of clinical cases." Ninety-two percent of the respondents stated that "the amount of effort to complete the requirements for this program was just right." Participants were also asked to rate each of the 8 sessions using the following scale: poor = 1 point, fair = 2, good = 3, and excellent = 4. The average rating for all 8 sessions was 3.61 points (SD = 0.55), which translates to 96% of the sessions being rated good or excellent. Eighty percent of the participants reported that the topics presented in the program were "excellent and clinically important to learn," and 20% of the participants reported that the topics presented were "good and somewhat important to learn." The participants were asked to evaluate their confidence regarding basic radiology skills before and after the program using the following scale: not confident at all = 1 point, somewhat confident = 2, moderately confident = 3, and very confident = 4. Figure 2 summarizes the responses of the participants.

Conclusions: An online course to teach the fundamentals of imaging modalities could be delivered through a webinar format to medical students and interns in several countries to address the potential gaps in radiology education, therefore increasing their understanding of the different imaging modalities and their proper use in medicine.
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http://dx.doi.org/10.1097/RCT.0000000000001306DOI Listing
July 2022

Liver imaging: it is time to adopt standardized terminology.

Eur Radiol 2022 Apr 7. Epub 2022 Apr 7.

Liver Imaging Group, Department of Radiology, University of California San Diego, San Diego, CA, USA.

Liver imaging plays a vital role in the management of patients at risk for hepatocellular carcinoma (HCC); however, progress in the field is challenged by nonuniform and inconsistent terminology in the published literature. The Steering Committee of the American College of Radiology (ACR)'s Liver Imaging Reporting And Data System (LI-RADS), in conjunction with the LI-RADS Lexicon Writing Group and the LI-RADS International Working Group, present this consensus document to establish a single universal liver imaging lexicon. The lexicon is intended for use in research, education, and clinical care of patients at risk for HCC (i.e., the LI-RADS population) and in the general population (i.e., even when LI-RADS algorithms are not applicable). We anticipate that the universal adoption of this lexicon will provide research, educational, and clinical benefits. KEY POINTS: •To standardize terminology, we encourage authors of research and educational materials on liver imaging to use the standardized LI-RADS Lexicon. •We encourage reviewers to promote the use of the standardized LI-RADS Lexicon for publications on liver imaging. •We encourage radiologists to use the standardized LI-RADS Lexicon for liver imaging in clinical care.
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http://dx.doi.org/10.1007/s00330-022-08769-5DOI Listing
April 2022

Multicenter Study of ACR Ultrasound LI-RADS Visualization Scores on Serial Examinations: Implications for Surveillance Strategies.

AJR Am J Roentgenol 2022 Jun 1:1-8. Epub 2022 Jun 1.

Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, Rm H-1307, Stanford, CA 94305.

The American College of Radiology Ultrasound LI-RADS includes the visualization score as a subjective measure of examination quality and the expected level of sensitivity. Whether a single suboptimal visualization score warrants a change in surveillance strategy is unknown. The purpose of this study is to determine the relative stability of visualization scores on serial surveillance ultrasound examinations in patients at risk for HCC. This retrospective study included patients at risk for HCC who underwent at least two HCC surveillance ultrasound examinations at one of three institutions between January 2017 and November 2020. The frequencies of the score remaining unchanged after variable numbers of preceding examinations with the given score were determined. A mixed-effects logistic model was fitted to identify factors associated with a repeat score of C (denoting severe limitations) versus a change to score A (indicating no or minimal limitations) or score B (denoting moderate limitations). A total of 3169 patients underwent at least two ultrasound examinations, yielding a total of 9602 examinations. A total of 8030 examinations (83.6%) were assigned score A; 1378 (14.4%), score B; and 194 (2.0%), score C. The frequency of score A was 88%, 91%, and 93% after one, two, and three consecutive prior examinations with score A, respectively. The frequency of score B was 45%, 48%, and 55% after one, two, and three consecutive prior examinations with score B. The frequency of score C was 42%, 67%, and 80% after one, two, and three consecutive prior examinations with score C. Among 109 examinations with score C in 91 patients with an available follow-up examination, no factor (including age, sex, severe steatosis, advanced cirrhosis, ascites, body mass index, and a change in the ultrasound machine, sonographer, or radiologist) was significantly associated with repeat score C (all > .05). Although not statistically significant, presence of severe steatosis and presence of advanced cirrhosis had the highest odds ratios (2.88 and 2.38, respectively) for repeat score C in multivariable analysis. Only 42% of patients with visualization score C on a single surveil-lance examinations have score C on follow-up examinations; however, after two or more score C examinations, the chance of future score C substantially increases. The findings may inform decisions regarding alternative surveil-lance strategies in patients with visualization score C on ultrasound. This decision should consider the number of previous examinations with score C.
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http://dx.doi.org/10.2214/AJR.22.27405DOI Listing
June 2022

Interpretable Machine Learning for Characterization of Focal Liver Lesions by Contrast-Enhanced Ultrasound.

IEEE Trans Ultrason Ferroelectr Freq Control 2022 05 27;69(5):1670-1681. Epub 2022 Apr 27.

This work proposes an interpretable radiomics approach to differentiate between malignant and benign focal liver lesions (FLLs) on contrast-enhanced ultrasound (CEUS). Although CEUS has shown promise for differential FLLs diagnosis, current clinical assessment is performed only by qualitative analysis of the contrast enhancement patterns. Quantitative analysis is often hampered by the unavoidable presence of motion artifacts and by the complex, spatiotemporal nature of liver contrast enhancement, consisting of multiple, overlapping vascular phases. To fully exploit the wealth of information in CEUS, while coping with these challenges, here we propose combining features extracted by the temporal and spatiotemporal analysis in the arterial phase enhancement with spatial features extracted by texture analysis at different time points. Using the extracted features as input, several machine learning classifiers are optimized to achieve semiautomatic FLLs characterization, for which there is no need for motion compensation and the only manual input required is the location of a suspicious lesion. Clinical validation on 87 FLLs from 72 patients at risk for hepatocellular carcinoma (HCC) showed promising performance, achieving a balanced accuracy of 0.84 in the distinction between benign and malignant lesions. Analysis of feature relevance demonstrates that a combination of spatiotemporal and texture features is needed to achieve the best performance. Interpretation of the most relevant features suggests that aspects related to microvascular perfusion and the microvascular architecture, together with the spatial enhancement characteristics at wash-in and peak enhancement, are important to aid the accurate characterization of FLLs.
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http://dx.doi.org/10.1109/TUFFC.2022.3161719DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9188683PMC
May 2022

Ovarian Cancer Detection in Average-Risk Women: Classic- versus Nonclassic-appearing Adnexal Lesions at US.

Radiology 2022 06 22;303(3):603-610. Epub 2022 Mar 22.

From the Department of Imaging Sciences, University of Rochester Medical Center, 601 Elmwood Ave, Box 648, Rochester, NY 14620 (A.G., T.M.B.); Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, Calif (P.J.); Department of Radiology, University of Michigan Health System, Ann Arbor, Mich (K.E.M.); Department of Radiology, Vanderbilt University Medical Center, Nashville, Tenn (K.P.L.); Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pa (H.M.Z.); Department of Radiology, Stanford University School of Medicine, Stanford, Calif (A.K., N.A.); and Department of Obstetrics and Gynecology (L.B.) and Department of Radiology (E.S.), University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wis.

Background Several US risk stratification schemas for assessing adnexal lesions exist. These multiple-subcategory systems may be more multifaceted than necessary for isolated adnexal lesions in average-risk women. Purpose To explore whether a US-based classification scheme of classic versus nonclassic appearance can be used to help appropriately triage women at average risk of ovarian cancer without compromising diagnostic performance. Materials and Methods This retrospective multicenter study included isolated ovarian lesions identified at pelvic US performed between January 2011 and June 2014, reviewed between September 2019 and September 2020. Lesions were considered isolated in the absence of ascites or peritoneal implants. Lesions were classified as classic or nonclassic based on sonographic appearance. Classic lesions included simple cysts, hemorrhagic cysts, endometriomas, and dermoids. Otherwise, lesions were considered nonclassic. Outcomes based on histopathologic results or clinical or imaging follow-up were recorded. Diagnostic performance and frequency of malignancy were calculated. Frequency of malignancy between age groups was compared using the χ test, and Poisson regression was used to explore relationships between imaging features and malignancy. Results A total of 970 isolated lesions in 878 women (mean age, 42 years ± 14 [SD]) were included. The malignancy rate for classic lesions was less than 1%. Of 970 lesions, 53 (6%) were malignant. The malignancy rate for nonclassic lesions was 32% (33 of 103) when blood flow was present and 8% (16 of 194) without blood flow ( < .001). For women older than 60 years, the malignancy rate was 50% (10 of 20 lesions) when blood flow was present and 13% (five of 38) without blood flow ( = .004). The sensitivity, specificity, positive predictive value, and negative predictive value of the classic-versus-nonclassic schema was 93% (49 of 53 lesions), 73% (669 of 917 lesions), 17% (49 of 297 lesions), and 99% (669 of 673 lesions), respectively, for detection of malignancy. Conclusion Using a US classification schema of classic- or nonclassic-appearing adnexal lesions resulted in high sensitivity and specificity in the diagnosis of malignancy in ovarian cancer. The highest risk of cancer was in isolated nonclassic lesions with blood flow in women older than 60 years. © RSNA, 2022 See also the editorial by Baumgarten in this issue.
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http://dx.doi.org/10.1148/radiol.212338DOI Listing
June 2022

Patient-Friendly Summary of the ACR Appropriateness Criteria: Sinonasal Disease: 2021 Update.

J Am Coll Radiol 2022 05 17;19(5):e25. Epub 2022 Mar 17.

Interim Chief, Body Imaging Division, Director of Ultrasound, Stanford University, Stanford, California. Electronic address:

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http://dx.doi.org/10.1016/j.jacr.2022.02.004DOI Listing
May 2022

Growth Kinetics and Progression Rate of Bosniak Classification Version 2019 Class III and IV Cystic Renal Masses on Imaging Surveillance.

AJR Am J Roentgenol 2022 Aug 16;219(2):244-253. Epub 2022 Mar 16.

Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, Rm H-1307, Stanford, CA 94305.

Active surveillance is increasingly used as first-line management for localized renal masses. Triggers for intervention primarily reflect growth kinetics, which have been poorly investigated for cystic masses defined by the Bosniak classification version 2019 (v2019). The purpose of this study was to determine growth kinetics and incidence rates of progression of class III and IV cystic renal masses, as defined by the Bosniak classification v2019. This retrospective study included 105 patients (68 men, 37 women; median age, 67 years) with 112 Bosniak v2019 class III or IV cystic renal masses on baseline renal mass protocol CT or MRI examinations performed from January 2005 to September 2021. Mass dimensions were measured. Progression was defined as any of the following: linear growth rate (LGR) of 5 mm/y or greater (representing the clinical guideline threshold for intervention), volume doubling time less than 1 year, T category increase, or N1 or M1 disease. Class III and IV masses were compared. Time to progression was estimated using Kaplan-Meier curve analysis. At baseline, 58 masses were class III and 54 were class IV. Median follow-up was 403 days. Median LGR for class III masses was 0.0 mm/y (interquartile range [IQR], -1.3 to 1.8 mm/y) and for class IV masses was 2.3 mm/y (IQR, 0.0-5.7 mm/y) ( < .001). LGR was at least 5 mm/y in four (7%) class III masses and 15 (28%) class IV masses ( = .005). Two patients, both with class IV masses, developed distant metastases. Incidence rate of progression for class III masses was 11.0 (95% CI, 4.5-22.8) and for class IV masses 73.6 (95% CI, 47.8-108.7) per 100,000 person-days of follow-up. Median time to progression was undefined for class III masses given the small number of progression events and 710 days for class IV masses. Hazard ratio of progression for class IV relative to class III masses was 5.1 (95% CI, 2.5-10.8; < .001). During active surveillance of cystic masses evaluated using the Bosniak classification v2019, class IV masses grew faster and were more likely to progress than class III masses. In comparison with current active surveillance guidelines that treat class III and IV masses similarly, future iterations may incorporate relatively more intensive surveillance for class IV masses.
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http://dx.doi.org/10.2214/AJR.22.27400DOI Listing
August 2022

Colonoscopy Versus Catheter Angiography for Lower Gastrointestinal Bleeding After Localization on CT Angiography.

J Am Coll Radiol 2022 04 28;19(4):513-520. Epub 2022 Feb 28.

Co-Chair, ACR Ultrasound LI-RADS®; Division Chief, Director of Ultrasound, and Assistant Fellowship Program Director, Body Imaging, Department of Radiology, Stanford University School of Medicine, Stanford, California.

Purpose: The aim of this study was to compare catheter angiography (CA) and colonoscopy outcomes after successful CT angiographic (CTA) localization for patients with overt lower gastrointestinal bleeding (LGIB).

Methods: Seventy-one consecutive patients from two institutions between 2010 and 2020 had both contrast extravasation on CTA imaging in the lower gastrointestinal tract and subsequent CA or colonoscopy. The primary outcome was confirmation of active bleeding during CA or colonoscopy (defined as confirmation yield). The secondary outcomes were to determine therapeutic yield (hemostatic therapy), time to procedure, rebleeding rate, and adverse outcome rates (defined as surgery, acute kidney injury, initiation of dialysis, and overall mortality). Univariate analyses and multivariable analyses with P < .05 were used to determine statistical significance.

Results: Forty-four patients underwent CA and 27 underwent colonoscopy. CA had higher overall confirmation yield (55% vs 26%, P = .026), whereas therapeutic yields were similar (70% vs 56%, P = .214). Time to procedure was 5.1 ± 3.4 hours for CA and 15.5 ± 13.6 hours for colonoscopy (P < .001). On multivariable analysis, shorter time to procedure was the only statistically significant predictor of confirmation yield (P = .037) and therapeutic yield (P = .013), whereas procedure, hemoglobin, transfusions, and hemodynamic instability were not. Adverse events and rebleeding were not statistically different between patients who underwent CA and colonoscopy (P > .05).

Conclusions: Shorter time to procedure was the only statistically significant predictor of confirmation and therapeutic yield after CTA localization of LGIB. Because CA can be performed sooner than colonoscopy without increased rates of adverse outcomes or rebleeding, CA may be a reasonable first-line treatment option in patients with CTA localization of LGIB.
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http://dx.doi.org/10.1016/j.jacr.2022.01.010DOI Listing
April 2022

Color Doppler Imaging of Vascular Abnormalities of the Uterus.

Ultrasound Q 2022 Mar;38(1):72-82

Department of Radiology, Stanford University School of Medicine, Stanford, CA.

Abstract: Many uterine abnormalities present clinically with bleeding encompassing a broad spectrum of patients from postmenopausal spotting to life-threatening hemorrhage. Color and spectral Doppler imaging of the pelvis is often the first crucial investigation used to quickly establish the correct etiology of the uterine bleeding and guide clinical decision making and patient management.
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http://dx.doi.org/10.1097/RUQ.0000000000000578DOI Listing
March 2022

Survey Study on the Experience, Practice Patterns, and Preferences of the Fellows of the Society of Radiologists in Ultrasound for Evaluation and Management of Gallbladder Polyps Detected With Ultrasound.

Ultrasound Q 2022 Jun 1;38(2):96-102. Epub 2022 Jun 1.

Department of Radiology, Stanford University Stanford Hospital and Clinics, Stanford, CA.

Abstract: Gallbladder polyps (GPs) are a common incidental finding on ultrasound; however, important differences in recommended management exist among professional society guidelines.An electronic survey was sent to 189 fellows of the Society of Radiologists in Ultrasound. Main outcomes included preferences and current practice patterns for evaluation, management, and surveillance of GPs as well as personal lifetime experience with gallbladder sonography and GPs.A total of 64 subjects (34%) with experience in gallbladder sonography completed the study. The estimated combined total number of gallbladder scans seen by the responders was 3,071,880. None of fellows had ever seen a pedunculated GP <1 cm detected on ultrasound that was proven to be malignant at the time of detection or during subsequent follow-up. All of the fellows used size as a feature to stratify recommendations. The median size threshold currently used by Society of Radiologists in Ultrasound fellows for recommending ultrasound follow-up was 6 mm, and their preferred threshold was 7 mm. The median size threshold for recommending surgical consultation was 10 mm, and the preferred threshold was 10 mm. Wall thickening and shape were considered important factors by 76% and 67% of respondents, respectively.Society of Radiologists in Ultrasound fellows tend to provide recommendations most similar to the American College of Radiology and Canadian Association of Radiology guidelines for management of GPs. Many would prefer guidelines that result in fewer recommendations for follow-up and surgical consultation. Despite a substantial combined experience, this survey did not uncover any case of a small GP that was malignant.
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http://dx.doi.org/10.1097/RUQ.0000000000000597DOI Listing
June 2022

Patient-Friendly Summary of the ACR Appropriateness Criteria: Transgender Breast Cancer Screening.

J Am Coll Radiol 2022 04 25;19(4):e19. Epub 2022 Jan 25.

Professor of Radiology, Chief of the Body Imaging Division, and Director of Ultrasound, Stanford University, Stanford, California. Electronic address:

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http://dx.doi.org/10.1016/j.jacr.2021.10.015DOI Listing
April 2022

Evaluation of early sonographic predictors of gangrenous cholecystitis: mucosal discontinuity and echogenic pericholecystic fat.

Abdom Radiol (NY) 2022 03 5;47(3):1061-1070. Epub 2022 Jan 5.

Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA, 94305, USA.

Purpose: To identify early sonographic features of gangrenous cholecystitis.

Materials And Methods: 101 patients with acute cholecystitis and a pre-operative sonogram were retrospectively reviewed by three radiologists in this IRB-approved and HIPAA-compliant study. Imaging data were correlated with histologic findings and compared using the Fisher's exact test or Student t test with p < 0.05 to determine statistical significance.

Results: Forty-eight patients had gangrenous cholecystitis and 53 had non-gangrenous acute cholecystitis. Patients with gangrenous cholecystitis tended to be older (67 ± 17 vs 48 ± 18 years; p = 0.0001), male (ratio of male:female 2:1 vs 0.6:1; p = 0.005), tachycardic (60% vs 28%; p = 0.001), and diabetic (25% vs 8%; p = 0.001). Median time between pre-operative sonogram and surgery was 1 day. On imaging, patients with gangrenous cholecystitis were more likely to have echogenic pericholecystic fat (p = 0.001), mucosal discontinuity (p = 0.010), and frank perforation (p = 0.004), while no statistically significant differences were seen in the presence of sloughed mucosa (p = 0.104), pericholecystic fluid (p = 0.523) or wall striations (p = 0.839). In patients with gangrenous cholecystitis and echogenic pericholecystic fat, a smaller subset had concurrent mucosal discontinuity (57%), and a smaller subset of those had concurrent frank perforation (58%). The positive likelihood ratios for gangrenous cholecystitis with echogenic fat and mucosal discontinuity were 4.6 (95% confidence interval 1.9-11.3) and 14.4 (2.0-106), respectively.

Conclusion: Echogenic pericholecystic fat and mucosal discontinuity are early sonographic findings that may help identify gangrenous cholecystitis prior to late findings of frank perforation.
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http://dx.doi.org/10.1007/s00261-021-03320-4DOI Listing
March 2022

ACR Appropriateness Criteria® Epigastric Pain.

J Am Coll Radiol 2021 11;18(11S):S330-S339

Specialty Chair; and Director, CT and MRI, and Section Chief, Abdominal Imaging, Virginia Commonwealth University Medical Center, Richmond, Virginia.

Epigastric pain can have multiple etiologies including myocardial infarction, pancreatitis, acute aortic syndromes, gastroesophageal reflux disease, esophagitis, peptic ulcer disease, gastritis, duodenal ulcer disease, gastric cancer, and hiatal hernia. This document focuses on the scenarios in which epigastric pain is accompanied by symptoms such as heartburn, regurgitation, dysphagia, nausea, vomiting, and hematemesis, which raise suspicion for gastroesophageal reflux disease, esophagitis, peptic ulcer disease, gastritis, duodenal ulcer disease, gastric cancer, or hiatal hernia. Although endoscopy may be the test of choice for diagnosing these entities, patients may present with nonspecific or overlapping symptoms, necessitating the use of imaging prior to or instead of endoscopy. The utility of fluoroscopic imaging, CT, MRI, and FDG-PET for these indications are discussed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.
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http://dx.doi.org/10.1016/j.jacr.2021.08.006DOI Listing
November 2021

Longitudinal Ultrasound Assessment of Changes in Size and Number of Incidentally Detected Gallbladder Polyps.

AJR Am J Roentgenol 2022 03 22;218(3):472-483. Epub 2021 Sep 22.

Stanford Hospital and Clinics, 300 Pasteur Dr, H1307, Stanford, CA 94305.

Previous European multisociety guidelines recommend routine follow-up imaging of gallbladder polyps (including polyps < 6 mm in patients without risk factors) and cholecystectomy for polyp size changes of 2 mm or more. The purpose of this study was to assess longitudinal changes in the number and size of gallbladder polyps on serial ultrasound examinations. This retrospective study included patients who underwent at least one ultrasound examination between January 1, 2010, and December 31, 2020 (as part of a hepatocellular carcinoma screening and surveillance program) that showed a gallbladder polyp. Number of polyps and size of largest polyp were recorded based primarily on review of examination reports. Longitudinal changes on serial examinations were summarized. Pathologic findings from cholecystectomy were reviewed. Among 9683 patients, 759 (8%) had at least one ultrasound examination showing a polyp. Of these, 434 patients (248 men, 186 women; mean age, 50.6 years) had multiple examinations (range, 2-19 examinations; mean, 4.8 examinations per patient; mean interval between first and last examinations, 3.6 ± 3.1 [SD] years; maximum interval, 11.0 years). Among these 434 patients, 257 had one polyp, 40 had two polyps, and 137 had more than two polyps. Polyp size was 6 mm or less in 368 patients, 7-9 mm in 52 patients, and 10 mm or more in 14 patients. Number of polyps increased in 9% of patients, decreased in 14%, both increased and decreased on serial examinations in 22%, and showed no change in 55%. Polyp size increased in 10% of patients, decreased in 16%, both increased and decreased on serial examinations in 18%, and showed no change in 56%. In 9% of patients, gallbladder polyps were not detected on follow-up imaging; in 6% of patients, gallbladder polyps were not detected on a follow-up examination but were then detected on later studies. No gallbladder carcinoma was identified in 19 patients who underwent cholecystectomy. Gallbladder polyps fluctuate in size, number, and visibility over serial examinations. Using a 2-mm threshold for growth, 10% increased in size. No carcinoma was identified. European multisociety guidelines that propose surveillance of essentially all polyps and a 2-mm size change as the basis for cholecystectomy are likely too conservative for clinical application.
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http://dx.doi.org/10.2214/AJR.21.26614DOI Listing
March 2022

Role of Ultrasound for Chronic Liver Disease and Hepatocellular Carcinoma Surveillance.

Magn Reson Imaging Clin N Am 2021 Aug;29(3):279-290

Department of Radiology, Stanford University, 300 Pasteur Drive H1307, Stanford, CA 94305, USA. Electronic address:

Ultrasound plays a vital role in the evaluation of patients with chronic liver disease and in hepatocellular carcinoma (HCC) surveillance in populations at risk for developing HCC. Semiannual ultrasound for HCC surveillance is universally recommended by all liver societies around the world. Advanced ultrasound techniques, such as elastography and contrast-enhanced ultrasound, offer additional benefits in imaging evaluation of chronic liver disease. Major benefits of ultrasound include its high safety profile and relatively low cost.
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http://dx.doi.org/10.1016/j.mric.2021.05.005DOI Listing
August 2021

Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) Visualization Score: a reliability analysis on inter-reader agreement.

Abdom Radiol (NY) 2021 11 6;46(11):5134-5141. Epub 2021 Jul 6.

Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Room H-1307, Stanford, CA, 94305, USA.

Background & Aim: The American College of Radiology Ultrasound Liver Imaging Reporting and Data System (ACR US LI-RADS) Visualization Score conveys the expected level of sensitivity of screening and surveillance ultrasound exams in patients at risk for hepatocellular carcinoma (HCC). We sought to determine inter-reader agreement of the Visualization Score which is currently unknown.

Methods: Consecutive 6998 ultrasound HCC screening and surveillance studies in 3115 patients from 2017 to 2020 were retrospectively retrieved. Of these, 6154 (87.9%) studies were Visualization A (No or minimal limitations), 709 (10.1%) were Visualization B (Moderate limitations), and 135 (1.9%) were Visualization C (Severe limitations). Randomly sampled 90 studies, with 30 studies in each Visualization category, were included for analysis. Nine radiologists (3 senior attendings, 3 junior attendings and 3 body imaging fellows) blinded to the original categorization independently reviewed each study and assigned a Visualization Score. Intraclass correlation coefficient (ICC) was used to quantify inter-reader agreement.

Results: ICC among all 9 radiologists was 0.70 (95% CI 0.63-0.77). ICCs among senior attendings, junior attendings and body imaging fellows were 0.68 (CI 0.58-0.76), 0.72 (CI 0.62-0.80) and 0.76 (CI 0.68-0.83), respectively. Subgroup analysis by liver parenchyma was further performed. ICC was highest in the patient group with normal liver parenchyma (0.69, CI 0.56-0.81), followed by steatosis (0.66, CI 0.54-0.79) and cirrhosis (0.58, CI 0.43-0.73), respectively.

Conclusions: US LI-RADS Visualization Score is a reliable tool with good inter-reader agreement that can be used to indicate the expected level of sensitivity of a screening and surveillance ultrasound examination for detecting focal liver observations.
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http://dx.doi.org/10.1007/s00261-021-03067-yDOI Listing
November 2021

Cystic artery velocity as a predictor of acute cholecystitis.

Abdom Radiol (NY) 2021 10 3;46(10):4720-4728. Epub 2021 Jul 3.

Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Room H-1307, Stanford, CA, 94305, USA.

Purpose: To evaluate angle-corrected peak systolic cystic artery velocity (CAv) as a predictor of acute cholecystitis among patients presenting to the emergency department (ED) with right upper quadrant (RUQ) pain.

Methods: In this IRB-approved and retrospective study, CAv was evaluated in 73 patients, 43 who underwent definitive treatment with cholecystectomy or percutaneous cholecystostomy and 30 control patients without clinical suspicion for cholecystitis. In addition to CAv, the following were reviewed by 3 radiologists: CBD diameter, cholelithiasis, impacted stone in the neck, sludge, gallbladder wall thickness > 3 mm, gallbladder transverse dimension ≥ 4 cm, longitudinal dimension ≥ 8 cm, tensile gallbladder fundus sign, pericholecystic fluid, pericholecystic echogenic fat, and sonographic Murphy sign.

Results: Of the 43 patients who underwent definitive treatment, 25 had acute cholecystitis (34%) and 18 (25%) had chronic cholecystitis. Average CAv measurements were 50 ± 16 cm/s (acute), 28 ± 8 cm/s (chronic), and 22 ± 8 cm/s (control; p < 0.0001). In univariate analysis, among patients who underwent definitive therapy, CAv ≥ 40 cm/s, gallbladder wall thickness, stone impaction, GB long dimension ≥ 8 cm, and elevated WBC were associated with acute cholecystitis (p < 0.05). In multivariate analysis, CAv ≥ 40 cm/s was the only statistically significant variable (p = 0.016). CAv ≥ 40 cm/s alone had a PPV of 94.7% and overall accuracy of 81.4% in diagnosing acute cholecystitis.

Conclusion: CAv ≥ 40 cm/s is highly associated with acute cholecystitis in patients presenting to the ED with RUQ pain.
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http://dx.doi.org/10.1007/s00261-021-03020-zDOI Listing
October 2021

Diagnostic Performance of 9 Quantitative Ultrasound Parameters for Detection and Classification of Hepatic Steatosis in Nonalcoholic Fatty Liver Disease.

Invest Radiol 2022 01;57(1):23-32

From the Department of Radiology, School of Medicine, Stanford University, California.

Background: Nonalcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease worldwide. Quantitative ultrasound (QUS) parameters based on radiofrequency raw data show promise in quantifying liver fat.

Purpose: The aim of this study was to evaluate the diagnostic performance of 9 QUS parameters compared with magnetic resonance imaging (MRI)-estimated proton density fat fraction (PDFF) in detecting and staging hepatic steatosis in patients with or suspected of NAFLD.

Materials And Methods: In this Health Insurance Portability and Accountability Act-compliant institutional review board-approved prospective study, 31 participants with or suspected of NAFLD, without other underlying chronic liver diseases (13 men, 18 women; average age, 52 years [range, 26-90 years]), were examined. The following parameters were obtained: acoustic attenuation coefficient (AC); hepatorenal index (HRI); Nakagami parameter; shear wave elastography measures such as shear wave elasticity, viscosity, and dispersion; and spectroscopy-derived parameters including spectral intercept (SI), spectral slope (SS), and midband fit (MBF). The diagnostic ability (area under the receiver operating characteristic curves and accuracy) of QUS parameters was assessed against different MRI-PDFF cutoffs (the reference standard): 6.4%, 17.4%, and 22.1%. Linearity with MRI-PDFF was evaluated with Spearman correlation coefficients (p).

Results: The AC, SI, Nakagami, SS, HRI, and MBF strongly correlated with MRI-PDFF (P = 0.89, 0.89, 0.88, -0.87, 0.81, and 0.71, respectively [P < 0.01]), with highest area under the receiver operating characteristic curves (ranging from 0.85 to 1) for identifying hepatic steatosis using 6.4%, 17.4%, and 22.1% MRI-PDFF cutoffs. In contrast, shear wave elasticity, shear wave viscosity, and shear wave dispersion did not strongly correlate to MRI-PDFF (P = 0.45, 0.38, and 0.07, respectively) and had poor diagnostic performance.

Conclusion: The AC, Nakagami, SI, SS, MBF, and HRI best correlate with MRI-PDFF and show high diagnostic performance for detecting and classifying hepatic steatosis in our study population.

Summary Statement: Quantitative ultrasound is an accurate alternative to MRI-based techniques for evaluating hepatic steatosis in patients with or at risk of NAFLD.

Key Findings: Our preliminary results show that specific quantitative ultrasound parameters accurately detect different degrees of hepatic steatosis in NAFLD.
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http://dx.doi.org/10.1097/RLI.0000000000000797DOI Listing
January 2022

Extravasation Volume at Computed Tomography Angiography Correlates With Bleeding Rate and Prognosis in Patients With Overt Gastrointestinal Bleeding.

Invest Radiol 2021 06;56(6):394-400

Departments of Radiology.

Objective: Despite the identification of active extravasation on computed tomography angiography (CTA) in patients with overt gastrointestinal bleeding (GIB), a large proportion do not have active bleeding or require hemostatic therapy at endoscopy, catheter angiography, or surgery. The objective of our proof-of-concept study was to improve triage of patients with GIB by correlating extravasation volume of first-pass CTA with bleeding rate and clinical outcomes.

Materials And Methods: All patients who presented with overt GIB and active extravasation on CTA from January 2014 to July 2019 were reviewed in this retrospective, institutional review board-approved and Health Insurance Portability and Accountability Act-compliant study. Extravasation volume was assessed using 3-dimensional software and correlated with hemostatic therapy (primary endpoint) and with intraprocedural bleeding, blood transfusions, and mortality as secondary endpoints using logistic regression models (P < 0.0125 indicating statistical significance). Odds ratios were used to determine the effect size of a threshold extravasation volume. Quantitative data (extravasation volume, aorta attenuation, extravasation attenuation and time) were input into a mathematical model to calculate bleeding rate.

Results: Fifty consecutive patients including 6 (12%) upper, 18 (36%) small bowel, and 26 (52%) lower GIB met inclusion criteria. Forty-two underwent catheter angiography, endoscopy, or surgery; 16 had intraprocedural active bleeding, and 24 required hemostatic therapy. Higher extravasation volumes correlated with hemostatic therapy (P = 0.007), intraprocedural active bleeding (P = 0.003), and massive transfusion (P = 0.0001), but not mortality (P = 0.936). Using a threshold volume of 0.80 mL or greater, the odds ratio of hemostatic therapy was 8.1 (95% confidence interval, 2.1-26), active bleeding was 11.8 (2.6-45), and massive transfusion was 18 (2.3-65). With mathematical modeling, extravasation volume had a direct and linear relationship with bleeding rate, and the lowest calculated detectable bleeding rate with CTA was less than 0.1 mL/min.

Conclusions: Larger extravasation volumes correlate with higher bleeding rates and may identify patients who require hemostatic therapy, have intraprocedural bleeding, and require blood transfusions. Current CTAs can detect bleeding rates less than 0.1 mL/min.
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http://dx.doi.org/10.1097/RLI.0000000000000753DOI Listing
June 2021

ACR Appropriateness Criteria® Liver Lesion-Initial Characterization.

J Am Coll Radiol 2020 Nov;17(11S):S429-S446

Specialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia.

Incidental liver masses are commonly identified on imaging performed for other indications. Since the prevalence of benign focal liver lesions in adults is high, even in patients with primary malignancy, accurate characterization of incidentally detected lesions is of paramount clinical importance. This document reviews utilization of various imaging modalities for characterization of incidentally detected liver lesions, discussed in the context of several clinical scenarios. For each clinical scenario, a summary of current evidence supporting the use of a given diagnostic modality is reported. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.
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http://dx.doi.org/10.1016/j.jacr.2020.09.005DOI Listing
November 2020

Online Liver Imaging Course; Pivoting to Transform Radiology Education During the SARS-CoV-2 Pandemic.

Acad Radiol 2021 01 6;28(1):119-127. Epub 2020 Oct 6.

Office of Educational Programs, McGovern Medical School at UT Health, Houston, Texas.

Purpose: The SARS-CoV-2 pandemic has drastically disrupted radiology in-person education. The purpose of this study was to assess the implementation of a virtual teaching method using available technology and its role in the continuity of education of practicing radiologists and trainees during the pandemic.

Methods: The authors created the Online Liver Imaging Course (OLIC) that comprised 28 online comprehensive lectures delivered in real-time and on-demand over six weeks. Radiologists and radiology trainees were asked to register to attend the live sessions. At the end of the course, we conducted a 46-question survey among registrants addressing their training level, perception of virtual conferencing, and evaluation of the course content.

Results: One thousand four hundred and thirty four radiologists and trainees completed interest sign up forms before the start of the course with the first webinar having the highest number of live attendees (343 people). On average, there were 89 live participants per session and 750 YouTube views per recording (as of July 9, 2020). After the end of the course, 487 attendees from 37 countries responded to the postcourse survey for an overall response rate of (33%). Approximately (63%) of participants were practicing radiologists while (37%) were either fellows or residents and rarely medical students. The overwhelming majority (97%) found the OLIC webinar series to be beneficial. Essentially all attendees felt that the webinar sessions met (43%) or exceeded (57%) their expectations. When asked about their perception of virtual conferences after attending OLIC lectures, almost all attendees (99%) enjoyed the virtual conference with a majority (61%) of the respondents who enjoyed the virtual format more than in-person conferences, while (38%) enjoyed the webinar format but preferred in-person conferences. When asked about the willingness to attend virtual webinars in the future, (84%) said that they would attend future virtual conferences even if in-person conferences resume while (15%) were unsure.

Conclusion: The success of the OLIC, attributed to many factors, indicates that videoconferencing technology provides an inexpensive alternative to in-person radiology conferences. The positive responses to our postcourse survey suggest that virtual education will remain to stay. Educational institutions and scientific societies should foster such models.
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http://dx.doi.org/10.1016/j.acra.2020.10.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7538097PMC
January 2021
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