Publications by authors named "Johannes Boos"

56 Publications

Impact of increasing levels of adaptive statistical iterative reconstruction on image quality in oil-based postmortem CT angiography in coronary arteries.

Int J Legal Med 2021 Feb 24. Epub 2021 Feb 24.

Medical Faculty, Department of Diagnostic and Interventional Radiology, University Dusseldorf, D-40225, Dusseldorf, Germany.

Introduction: Postmortem multi-detector computed tomography (PMCT) has become an important part in forensic imaging. Modern reconstruction techniques such as iterative reconstruction (IR) are frequently used in postmortem CT angiography (PMCTA). The image quality of PMCTA depends on the strength of IR. For this purpose, we aimed to investigate the impact of different advanced IR levels on the objective and subjective PMCTA image quality.

Material And Methods: We retrospectively analyzed the coronary arteries of 27 human cadavers undergoing whole-body postmortem CT angiography between July 2017 and March 2018 in a single center. Iterative reconstructions of the coronary arteries were processed in five different level settings (0%; 30%; 50%; 70%; 100%) by using an adaptive statistical IR method. We evaluated the objective (contrast-to-noise ratio (CNR)) and subjective image quality in several anatomical locations.

Results: Our results demonstrate that the increasing levels of an IR technique have relevant impact on the image quality in PMCTA scans in forensic postmortem examinations. Higher levels of IR have led to a significant reduction of image noise and therefore to a significant improvement of objective image quality (+ 70%). However, subjective image quality is inferior at higher levels of IR due to plasticized image appearance.

Conclusion: Objective image quality in PMCTA progressively improves with increasing level of IR with the best CNR at the highest IR level. However, subjective image quality is best at low to medium levels of IR. To obtain a "classic" image appearance with optimal image quality, PMCTAs should be reconstructed at medium levels of IR.
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http://dx.doi.org/10.1007/s00414-021-02530-1DOI Listing
February 2021

Effective dose of radiation per screw in surgery of adolescent idiopathic scoliosis: matched pair analysis of 293 pedicle screws inserted using three different techniques.

J Child Orthop 2020 Dec;14(6):554-561

Department of Orthopedic Surgery, University Hospital of Duesseldorf, Duesseldorf, Germany.

Purpose: Reports on heterogenous groups of patients have indicated that pedicle screw insertion guided by navigation (PIN) leads to, for the patient, higher doses of radiation compared with pedicle screw insertion guided by fluoroscopy (PIF). This would be a major concern, especially in paediatric deformity correction.

Methods: After a power analysis (aiming at > 0.8) 293 pedicle screws which were inserted in patients with adolescent idiopathic scoliosis were analyzed by comparing effective dose and fluoroscopy time per screw for three different techniques. Groups 2 and 3 were matched to Group 1 by Lenke type of scoliosis. Group 1 were prospectively enrolled consecutive patients that have been operated on by PIN with image acquisition by preoperative CT scan (CTS). Group 2 were consecutive retrospectively matched patients who have been operated on by PIN with image acquisition by an intraoperative 3D scan (3DS). Group 3 were consecutive retrospectively matched patients who have been operated on by PIF.

Results: Mean dose of radiation per screw was 1.0 mSv (sd 0.8) per screw in CTS patients, 0.025 mSv (sd 0.001) per screw in 3DS patients and 0.781 mSv (sd 0.12) per screw in PIF patients. The difference was significant (p < 0.0001).

Conclusion: When we compared different techniques of navigation, navigation by image acquisition with CTS showed a significantly higher (by 97.5%) dose of radiation per screw for the patient than navigation by image acquisition by a 3DS. Navigation by 3DS showed significantly lower effective dose per screw for the adolescent patients than the fluoroscopic technique.

Level Of Evidence: II.
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http://dx.doi.org/10.1302/1863-2548.14.200148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7740690PMC
December 2020

Diagnostic value and forensic relevance of a novel photorealistic 3D reconstruction technique in post-mortem CT.

Br J Radiol 2020 Aug 18;93(1112):20200204. Epub 2020 Jun 18.

Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225, Dusseldorf, Germany.

Objectives: Evaluation of performance and forensic relevance of a novel, photorealistic, 3D reconstruction method (cinematic rendering, (CR)) in comparison with conventional post-mortem CT (PMCT) and volume rendering (VR) technique for visualization of traumatic injuries.

Methods: 112 pathologies (fractures, soft tissue injuries and foreign bodies) from 33 human cadavers undergoing whole body PMCT after traumatic death were retrospectively analyzed. Pathologies were reconstructed with CR and VR techniques. Fractures were classified according to their dislocation. Images were evaluated according to their expressiveness and judicial relevance by two forensic pathologists using a five-level Likert-scale (1: high expressiveness, 5: low expressiveness). They decided whether CR reconstructions were suitable for judicial reviews. The detection rate of pathologies was determined by two radiologists.

Results: CR was more expressive than VR for all three trauma categories ( < 0.01) and than conventional CT when used for fractures with dislocation ( < 0.001), injuries of the ventral body surface ( < 0.001), and demonstration of foreign bodies ( = 0.033). CR and VR became more expressive with a higher grade of fracture dislocation ( < 0.001). 20% of all pathologies in the CR and VR reconstructions were not detectable by radiologists.

Conclusion: CR reconstructions are superior to VR regarding the expressiveness. For fractures with substantial dislocation, soft tissue injuries, and foreign bodies , CR showed a significantly better expressiveness than conventional PMCT. CR and VR have significant limitations in cases of fractures with minor dislocations and covered soft tissue injuries.

Advances In Knowledge: CR is a helpful tool to present pathologies found in PMCT for judicial reviews.
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http://dx.doi.org/10.1259/bjr.20200204DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7446014PMC
August 2020

Impact of different iterative metal artifact reduction (iMAR) algorithms on PET/CT attenuation correction after port implementation.

Eur J Radiol 2020 Aug 15;129:109065. Epub 2020 May 15.

University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Dusseldorf, Germany.

Purpose: To evaluate the effect of various interactive metal artifact reduction (iMAR) algorithms on attenuation correction in the vicinity of port chambers in PET/CT.

Material And Methods: In this prospective study, 30 oncological patients (12 female, 18 male, mean age 59.6 ± 10.5y) with implanted port chambers undergoing 18F-FDG PET/CT were included. CT images were reconstructed with standard weighted filtered back projection (WFBP) and three different iMAR algorithms (hip, dental filling (DF) and pacemaker (PM)). PET attenuation correction was performed with all four CT datasets. SUVmean, SUVmax and HU measurements were performed in fat and muscle tissue in the vicinity of the port chamber at the location of the strongest bright and dark band artifacts. Differences between HU and SUV values across all CT- and PET-images were investigated using a paired t-test. Bonferroni correction was used to prevent alpha-error accumulation (p < 0.008).

Results: In comparison to WFBP (fat: 94.2 ± 53.9 HU, muscle: 197.6 ± 49.2 HU) all three iMAR algorithms led to a decrease of HU in bright band artifacts. iMAR-DF led to a decrease of 159.2 % (fat: -51.9 ± 58.5 HU, muscle: 94.5 ± 55.3 HU), iMAR-hip of 138.3 % (fat: -30.3 ± 58.5, muscle: 70.4 ± 28.8) and iMAR-PM of 122.3 % (fat: -21.2 ± 47.2 HU, muscle: 72.5 ± 25.1 HU; for all p < 0.008). There was no significant effect of iMAR on SUV measurements in comparison to WFBP.

Conclusion: iMAR leads to a significant change of HU values in artifacts caused by port catheter chambers in comparison to WFBP. However, no significant differences in attenuation correction and consecutive changes in SUV measurements can be observed.
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http://dx.doi.org/10.1016/j.ejrad.2020.109065DOI Listing
August 2020

Single-Energy Retrospective Metal Artifact Reduction Using Adaptive Thresholding for Metal Implants in the Abdomen and Pelvis.

J Comput Assist Tomogr 2020 May/Jun;44(3):443-449

From the Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.

Objective: To assess impact of single-energy metal artifact reduction (SEMAR) algorithm utilizing retrospective adaptive thresholding in reducing metal artifacts in the abdomen and pelvis.

Methods: In this prospective institutional review board-approved, Health Insurance Portability and Accountability Act-compliant study, 90 patients with various metals (n = 97) on computed tomography of abdomen and pelvis (Canon Medical, Aquilion ONE and PRIME) scanned 07/2017-09/2018 with SEMAR retrospectively applied were included. Density was measured in the near and far field to the metals. Density standard deviation (SD), representing artifact severity, was compared with and without SEMAR applied. Two trained human observers independently evaluated severity of artifacts on a five-point scale (0, no artifact; 5, severe artifact).

Results: The SEMAR significantly decreased artifact severity in the near field of high-density metal implants (SD of 204 ± 101HU without vs. 66 ± 40HU with SEMAR, P < 0.001). In the far field, the artifact severity was similar (40 ± 31HU without vs. 36 ± 27HU with SEMAR, P = 0.41). Artifact severity was decreased adjacent to low-density metal in the near field (SD of 86 ± 56HU without vs 49 ± 30HU with SEMAR, P < 0.001). In the far field to the low-density metals artifact severity was similar (33 ± 29HU without vs. 31 ± 27HU with SEMAR, P = 0.79). Subjectively, artifacts severity decreased for high-density metals in near field by 1.3 ± 1.0, and in far field by 0.7 ± 0.7 and for low-density metals in the near field by 0.7 ± 1.0, far field 0.4 ± 0.5, all P < 0.05.

Conclusions: The SEMAR retrospective algorithm with adaptive thresholding subjectively and objectively reduced near-field artifacts generated by high- and low-density metals.
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http://dx.doi.org/10.1097/RCT.0000000000001013DOI Listing
May 2020

Is CT-based cinematic rendering superior to volume rendering technique in the preoperative evaluation of multifragmentary intraarticular lower extremity fractures?

Eur J Radiol 2020 May 21;126:108911. Epub 2020 Feb 21.

University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen, Germany.

Purpose: Cinematic rendering (CR), a recently launched, FDA-approved rendering technique converts CT image datasets into nearly photorealistic 3D reconstructions by using a unique lighting model. The purpose of this study was to compare CR to volume rendering technique (VRT) images in the preoperative visualization of multifragmentary intraarticular lower extremity fractures.

Method: In this retrospective study, CT datasets of 41 consecutive patients (female: n = 13; male: n = 28; mean age: 52.3 ± 17.9y) with multifragmentary intraarticular lower extremity fractures (calcaneus: n = 16; tibial pilon: n = 19; acetabulum: n = 6) were included. All datasets were acquired using a 128-row dual-source CT. A dedicated workstation was used to reconstruct CR and VRT images which were reviewed independently by two experienced board-certified traumatologists trained in special trauma surgery. Image quality, anatomical accuracy and fracture visualization were assessed on a 6-point-Likert-scale (1 = non-diagnostic; 6=excellent). The regular CT image reconstructions served as reverence standard. For each score, median values between both readers were calculated. Scores of both reconstruction methods were compared using a Wilcoxon-Ranksum test with p < 0.05 indicating statistical significance. Inter-reader agreement was calculated using Spearman's rank correlation coefficient.

Results: Compared to VRT, CR demonstrated a higher image quality (VRT:2.5; CR:6.0; p < 0.001), a higher anatomical accuracy (VRT:3.5; CR:5.5; p < 0.001) and provided a more detailed visualization of the fracture (VRT:2.5; CR:6.0; p < 0.001). An additional benefit of CR reconstructions compared to VRT reconstructions was reported by both readers in 65.9 % (27/41) of all patients.

Conclusions: CR reconstructions are superior to VRT due to higher image quality and higher anatomical accuracy. Traumatologists find CR reconstructions to improve visualization of lower extremity fractures which should thus be used for fracture demonstration during interdisciplinary conferences.
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http://dx.doi.org/10.1016/j.ejrad.2020.108911DOI Listing
May 2020

Minimizing Radiation Dose Outliers Through Systematic Analysis, Computed Tomography Technologist Education, and Standardized System Solutions.

J Comput Assist Tomogr 2021 Jan-Feb 01;45(1):78-83

From the Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA.

Objectives: The aims of the study were to systematically analyze causes for radiation dose outliers in emergency department noncontrast head computed tomographies (CTs), to develop and implement standardized system solutions, and audit program success for an extended period of time.

Methods: This study was performed in a large, tertiary academic center between January 2015 and September 2017. Four phases of radiation dose data collection with and without prior interventions were performed. Outliers from 5 categories were evaluated for appropriateness in consensus by 2 radiologists and a senior CT technologist.

Results: A total of 275 ± 15 CTs per period were included. Fifty-seven inappropriate scanning parameters were found in 24 (9%) of 254 CTs during the first analysis, 27 in 21 (7%) of 290 CTs during the second, 11 in 10 (4%) of 276 during the third assessment (P = 0.006). After a year without additional intervention, the number remained stable (14 in 11/281 CTs, 4%).

Conclusions: Combining a dose reporting system, individual case analysis, staff education, and implementation of systemic solutions lead to sustained radiation exposure improvement.
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http://dx.doi.org/10.1097/RCT.0000000000000985DOI Listing
January 2021

Impact of different metal artifact reduction techniques on attenuation correction in 18F-FDG PET/CT examinations.

Br J Radiol 2020 Jan 1;93(1105):20190069. Epub 2019 Nov 1.

Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225 Dusseldorf, Germany.

Objective: To evaluate the impact of different metal artifact reduction (MAR) algorithms on Hounsfield unit (HU) and standardized uptake values (SUV) in a phantom setting and verify these results in patients with metallic implants undergoing oncological PET/CT examinations.

Methods And Materials: In this prospective study, PET-CT examinations of 28 oncological patients (14 female, 14 male, mean age 69.5 ± 15.2y) with 38 different metal implants were included. CT datasets were reconstructed using standard weighted filtered back projection (WFBP) without MAR, MAR in image space (MARIS) and iterative MAR (iMAR, hip algorithm). The three datasets were used for PET attenuation correction. SUV and HU measurements were performed at the site of the most prominent bright and dark band artifacts. Differences between HU and SUV values across the different reconstructions were compared using paired t-tests. Bonferroni correction was used to prevent alpha-error accumulation ( < 0.017).

Results: For bright band artifacts, MARIS led to a non-significant mean decrease of 12.0% (345 ± 315 HU) in comparison with WFBP (391 ± 293 HU), whereas iMAR led to a significant decrease of 68.3% (125 ± 185 HU, < 0.017). For SUVmean, MARIS showed no significant effect in comparison with WFBP (WFBP: 0.99 ± 0.40, MARIS: 0.96 ± 0.39), while iMAR led to a significant decrease of 11.1% (0.88 ± 0.35, < 0.017). Similar results were observed for dark band artifacts.

Conclusion: iMAR significantly reduces artifacts caused by metal implants in CT and thus leads to a significant change of SUV measurements in bright and dark band artifacts compared with WFBP and MARIS, thus probably improving PET quantification.

Advances In Knowledge: The present work indicates that MAR algorithms such as iMAR algorithm in integrated PET/CT scanners are useful to improve CT image quality as well as PET quantification in the evaluation of tracer uptake adjacent to large metal implants. A detailed analysis of oncological patients with various large metal implants using different MAR algorithms in PET/CT has not been conducted yet.
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http://dx.doi.org/10.1259/bjr.20190069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6948077PMC
January 2020

Development of size-specific institutional diagnostic reference levels for computed tomography protocols in neck imaging.

J Radiol Prot 2020 Mar 11;40(1):68-82. Epub 2019 Oct 11.

University Düsseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Düsseldorf, Germany.

Purpose: To develop size-specific institutional diagnostic reference levels (DRLs) for computed tomography (CT) protocols used in neck CT imaging (cervical spine CT, cervical CT angiography (CTA) and cervical staging CT) and to compare institutional to national DRLs.

Materials And Methods: Cervical CT examinations (spine, n = 609; CTA, n = 505 and staging CT, n = 184) performed between 01/2016 and 06/2017 were included in this retrospective study. For each region and examination, the volumetric CT dose index (CTDI) and dose-length product (DLP) were determined and binned into size bins according to patient water-equivalent diameter (d). Linear regression analysis was performed to calculate size-specific institutional DRLs for CTDI and DLP, applying the 75th percentile as the upper limit for institutional DRLs. The mean institutional CTDI and DLP were compared to national DRLs (CTDI 20 mGy for cervical spine CT (DLP 300 mGycm) and cervical CTA (DLP 600 mGycm), and CTDI 15 mGy for cervical staging CT (DLP 330 mGycm)).

Results: The mean CTDI and DLP (±standard deviation) were 15.2 ± 4.1 mGy and 181.5 ± 88.3 mGycm for cervical spine CT; 8.1 ± 4.3 mGy and 280.2 ± 164.3 mGycm for cervical CTA; 8.6 ± 1.9 mGy and 162.8 ± 85.0 mGycm for cervical staging CT. For all CT protocols, there was a linear increase in CTDI and DLP with increasing d. For the CTDI, size-specific institutional DRLs increased with d from 14 to 29 mGy for cervical spine CT, from 5 to 17 mGy for cervical CTA and from 8 to 13 mGy for cervical staging CT. For the DLP, size-specific institutional DRLs increased with d from 130 to 510 mGycm for cervical spine CT, from 140 to 640 mGycm for cervical CTA and from 140 to 320 mGycm for cervical staging CT. Institutional DRLs were lower than national DRLs by 81% and 67% for cervical spine CT (d = 17.8 cm), 43% and 51% for cervical CTA (d = 19.5 cm) and 59% and 53% for cervical staging CT (d = 18.8 cm) for CTDI and DLP, respectively.

Conclusion: Size-specific institutional DRLs were generated for neck CT examinations. The mean institutional CTDI and DLP values were well below national DRLs.
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http://dx.doi.org/10.1088/1361-6498/ab4d00DOI Listing
March 2020

Uterine Artery Embolization with Gelfoam for Acquired Symptomatic Uterine Arteriovenous Shunting.

J Vasc Interv Radiol 2019 Nov 10;30(11):1750-1758. Epub 2019 Aug 10.

Department of Radiology, Beth Israel Deaconess Medical Center, One Deaconess Rd., WCC-3, Boston, MA 02215. Electronic address:

Purpose: To evaluate the technical and clinical success rates and safety of bilateral gelfoam uterine artery embolization (UAE) for symptomatic acquired uterine arteriovenous shunting due to prior obstetric or gynecologic event.

Materials And Methods: This was a retrospective study of consecutive patients of reproductive age who presented with abnormal uterine bleeding after recent gynecologic procedures or obstetric events between January 2013 and February 2018. Bilateral UAE was performed in all patients using gelfoam slurry. Technical success was defined as angiographic resolution of arteriovenous shunting. Clinical success was defined as cessation of symptomatic bleeding, resolution on follow-up imaging, or minimal estimated blood loss (EBL) (<50 ml) on subsequent elective dilation and curettage (D&C) procedure.

Results: Eighteen patients (mean age, 32.8 ± 7.1 years) were included. Technical success and clinical success were experienced by 17/18 (94.4%) and 16/17 (94.1%) patients, respectively. Angiography demonstrated arteriovenous shunting in 18/18 (100%) patients, with early venous drainage. Seven of 18 (38.9%) patients underwent subsequent scheduled D&C due to remaining retained products of conception, with an EBL of 17.9 ± 15.6 ml. There was 1 minor complication of a self-limited vascular access groin hematoma (1/18, 5.6%) and 1 major complication (1/18, 5.6%) of a pulmonary embolism detected 3 days after UAE. The length of clinical follow-up was 19.3 ± 15.5 months, in which 41.2% (7/17) of the patients became pregnant.

Conclusions: UAE with gelfoam alone for symptomatic uterine arteriovenous shunting is a feasible treatment option that has a high technical and clinical success rate with a low rate of complications.
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http://dx.doi.org/10.1016/j.jvir.2019.04.002DOI Listing
November 2019

MRI identifies biochemical alterations of intervertebral discs in patients with low back pain and radiculopathy.

Eur Radiol 2019 Dec 5;29(12):6443-6446. Epub 2019 Jul 5.

Medical Faculty, Department of Diagnostic and Interventional Radiology, University Dusseldorf, 40225, Dusseldorf, Germany.

Key Points: • Molecular intervertebral disc damage was associated with LBP and radiculopathy.• Patients with radiculopathy and LBP demonstrated a depletion of gagCEST values compared with healthy controls.• GagCEST imaging may be a non-invasive tool for investigation of degeneration processes of lumbar intervertebral discs (IVDs). GagCEST imaging may be an imaging biomarker for biochemical IVD alterations.
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http://dx.doi.org/10.1007/s00330-019-06305-6DOI Listing
December 2019

Prospective comparison of whole-body MRI and Ga-PSMA PET/CT for the detection of biochemical recurrence of prostate cancer after radical prostatectomy.

Eur J Nucl Med Mol Imaging 2019 Jul 16;46(7):1542-1550. Epub 2019 Mar 16.

Department of Nuclear Medicine, University Dusseldorf, Medical Faculty, 40225, Dusseldorf, Germany.

Purpose: To assess whole-body magnetic resonance imaging (wb-MRI) for detection of biochemical recurrence in comparison to Ga-prostate-specific membrane antigen positron emission tomography/computed tomography (Ga-PSMA PET/CT) in prostate cancer (Pca) patients after radical prostatectomy.

Methods: This was a prospective trial including 28 consecutive patients (mean age 65.3 ± 9.0 years) with newly documented biochemical recurrence of Pca (mean prostate-specific antigen, PSA, 2.09 ± 1.95 ng/ml) following radical prostatectomy. All patients underwent both wb-MRI including a dedicated pelvic imaging protocol and PET/CT with 166 ± 35 MBq Ga-PSMA within a time window of 11 ± 10 days. PET/CT and MRI datasets were separately evaluated regarding Pca lesion count, type, localization and diagnostic confidence (three-point Likert scale, 1-3) by two nuclear medicine specialists and two radiologists, respectively. The reference standard was based on histopathological results, PSA levels following targeted salvage irradiation and follow-up imaging. Lesion-based and patient-based detection rates were compared using the chi-squared test. Differences in diagnostic confidence were assessed using the Welch test.

Results: A total of 56 Pca lesions were detected in 20 of the 28 patients. Ga-PSMA PET/CT detected 56 of 56 lesions (100%) in 20 patients (71.4%), while wb-MRI detected 13 lesions (23.2%) in 11 patients (39.3%). The higher detection rate with Ga-PSMA PET/CT was statistically significant on both a per-lesion basis (p < 0.001) and a per-patient basis (p = 0.0167). In 8 patients (28.6%) no relapse was detectable by either modality. All lesions detected by wb-MRI were also detected by Ga-PSMA PET/CT. Additionally, Ga-PSMA PET/CT provided superior diagnostic confidence in identifying Pca lesions (2.7 ± 0.7 vs. 2.3 ± 0.6, p = 0.044).

Conclusion: Ga-PSMA PET/CT significantly out-performed wb-MRI in the detection of biochemical recurrence in Pca patients after radical prostatectomy.
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http://dx.doi.org/10.1007/s00259-019-04308-5DOI Listing
July 2019

Adnexal mass staging CT with a disease-specific structured report compared to simple structured report.

Eur Radiol 2019 Sep 28;29(9):4851-4860. Epub 2019 Feb 28.

Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA, 02215, USA.

Objectives: To assess a disease-specific structured report (dsSR) for CT staging of ovarian malignancy compared to a simple structured report (sSR).

Methods: This is a HIPAA-compliant, IRB-approved study with waiver of informed consent. An adnexal mass-specific structured reporting CT template was developed in collaboration between gynecologic oncologists and diagnostic radiologists. The study population included 24 consecutive women who had a staging CT prior to undergoing debulking surgery for a primary ovarian malignancy. Objective evaluation by radiologists for the presence of 19 key features and subjective evaluation by gynecologic oncologists were performed to assess the clarity and usefulness for procedural planning of dsSR and sSR. Accuracy, sensitivity, and specificity were assessed using operating room notes and pathology reports as the reference standard.

Results: Fewer key features were missing from dsSR than sSR: 0.2 ± 0.8 (range 0-2) vs.10.2 ± 1.7 (range 7-14), respectively (p < 0.0001). Compared to sSR, gynecologic oncologists deemed dsSR more helpful (4.3 ± 0.7 vs. 3.7 ± 0.8, p < 0.0001) and easier to understand (4.3 ± 0.6 vs. 3.9 ± 0.7, p = 0.0057) (on a scale 0-5, 0 not helpful/very difficult to understand; 5 extremely helpful/very clear to understand). Gynecologic oncologists reported a higher rate of potential to modify their surgical approach based on dsSR (33-42%) compared to sSR (13-17%), p = 0.004.

Conclusions: Disease-specific structured reports were more reliable than simple structured reports in describing key features essential for procedural planning. dsSR was described as more helpful and easier to understand and more likely to lead to modification of the surgical approach by gynecologic oncologists compared to sSR.

Key Points: • Disease-specific structured report is easier to understand and more helpful for planning gynecological surgery as compared with simple structured report. • Disease-specific structured report for pre-operative evaluation of ovarian cancer provides better documentation of essential features required for surgical planning as compared with simple structured report. • Disease-specific structured report has the potential to modify the surgical approach as assessed by gynecologic oncologists.
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http://dx.doi.org/10.1007/s00330-019-06037-7DOI Listing
September 2019

Implementation of Institutional Size-Specific Diagnostic Reference Levels for CT Angiography.

Acad Radiol 2019 12 22;26(12):1661-1667. Epub 2019 Feb 22.

University Duesseldorf, Department of Diagnostic and Interventional Radiology, Moorenstraße 5, 40225 Duesseldorf, Germany.

Rationale And Objectives: To generate institutional size-specific diagnostic reference levels (DRLs) for computed tomography angiography (CTA) examinations and assess the potential for dose optimization compared to size-independent DRLs.

Materials And Methods: CTA examinations of the aorta, the pulmonary arteries and of the pelvis/lower extremity performed between January 2016 and January 2017 were included in our retrospective study. Water equivalent diameter (Dw) was automatically calculated for each patient. The relationship between Dw and computed tomography dose index (CTDI) was analyzed and the 75th percentile was chosen as the upper limit for institutional DRLs. Size-specific institutional DRLs were compared to national size-independent DRLs from Germany and the UK.

Results: A total of 1344 examinations were included in our study (n = 733 aortic CTA, n = 406 pulmonary CTA, n = 205 pelvic/lower extremity CTA). Mean Dw was 26 ± 9 cm and mean CTDI was 7.0 ± 4.6 mGy. For all CTA protocols, there was a linear progression of CTDI with increasing Dw with an R² = 0.95 in aortic CTA, R² = 0.94 in pulmonary CTA and R² = 0.93 in pelvic/lower extremity CTA. Median CTDI increased by 0.57 mGy per additional cm Dw in aortic CTA, by 1.1 mGy in pulmonary CTA and by 0.31 mGy in pelvic/lower extremity CTA. Institutional DRLs were lower than national DRLs for average size patients (aortic CTA: Dw 28.2 cm, CTDI 7.6 mGy; pulmonary CTA, Dw 27.9 cm, CTDI 11.8 mGy; pelvic/lower extremity CTA, Dw 20.0 cm, CTDI 6.4 mGy). More dose outliers in small patients were detected with size-specific DRLs compared to national size-independent DRLs (56.4% vs 16.2%).

Conclusion: We implemented institutional size-specific DRLs for CTA examinations which enabled a more precise analysis compared to national sizeindependent DRLs.
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http://dx.doi.org/10.1016/j.acra.2019.01.019DOI Listing
December 2019

Potential of a machine-learning model for dose optimization in CT quality assurance.

Eur Radiol 2019 Jul 19;29(7):3705-3713. Epub 2019 Feb 19.

Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, 40225, Dusseldorf, Germany.

Objectives: To evaluate machine learning (ML) to detect chest CT examinations with dose optimization potential for quality assurance in a retrospective, cross-sectional study.

Methods: Three thousand one hundred ninety-nine CT chest examinations were used for training and testing of the feed-forward, single hidden layer neural network (January 2016-December 2017, 60% male, 62 ± 15 years, 80/20 split). The model was optimized and trained to predict the volumetric computed tomography dose index (CTDI) based on scan patient metrics (scanner, study description, protocol, patient age, sex, and water-equivalent diameter (D)). The root mean-squared error (RMSE) was calculated as performance measurement. One hundred separate, consecutive chest CTs were used for validation (January 2018, 60% male, 63 ± 16 years), independently reviewed by two blinded radiologists with regard to dose optimization, and used to define an optimal cutoff for the model.

Results: RMSE was 1.71, 1.45, and 1.52 for the training, test, and validation dataset, respectively. The scanner and D were the most important features. The radiologists found dose optimization potential in 7/100 of the validation cases. A percentage deviation of 18.3% between predicted and actual CTDI was found to be the optimal cutoff: 8/100 cases were flagged as suboptimal by the model (range 18.3-53.2%). All of the cases found by the radiologists were identified. One examination was flagged only by the model.

Conclusions: ML can comprehensively detect CT examinations with dose optimization potential. It may be a helpful tool to simplify CT quality assurance. CT scanner and D were most important. Final human review remains necessary. A threshold of 18.3% between the predicted and actual CTDI seems adequate for CT quality assurance.

Key Points: • Machine learning can be integrated into CT quality assurance to improve retrospective analysis of CT dose data. • Machine learning may help to comprehensively detect dose optimization potential in chest CT, but an individual review of the results by an experienced radiologist or radiation physicist is required to exclude false-positive findings.
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http://dx.doi.org/10.1007/s00330-019-6013-6DOI Listing
July 2019

Noise insertion in CT for cocaine body packing: where is the limit of extensive dose reduction?

Eur J Med Res 2018 Dec 7;23(1):59. Epub 2018 Dec 7.

Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Moorenstr. 5, 40225, Dusseldorf, Germany.

Background: To evaluate the detection rate and image quality in CT-body-packer-screening at different radiation-dose levels and to determine a dose threshold that enables a reliable detection of incorporated body packs and incidental findings with a maximum of dose saving.

Materials And Methods: We retrospectively included 27 individuals who underwent an abdominal CT with automated exposure control due to suspected body packing. CT images were reconstructed at different radiation-dose levels of 50%, 10, 5% and 1% using iterative reconstructions. All 135 CT reconstructions were evaluated by three independent readers. Reviewers determined the presence of foreign bodies and evaluated the image quality using a 5-point ranking scale. In addition, visualization of incidental findings was assessed.

Results: A threshold of 5% (effective dose 0.11 ± 0.07 mSv) was necessary to correctly identify all 27 patients with suspected body packing. Extensive noise insertion to a dose level of 1% (0.02 ± 0.01 mSV) led to false-positive solid cocaine findings in three patients. Image quality was comparable between 100 and 50%. The threshold for correct identification of incidental findings was 10% of the initial dose (effective dose 0.21 ± 0.13 mSv).

Conclusions: Our results indicate that dose of abdominal CT for the detection of intracorporeal cocaine body packets can be markedly reduced to up to 5% of the initial dose while still providing sufficient image quality to detect ingested body packets. However, a minimum effective dose of 0.21 mSv (10% of initial dose) seems to be required to properly identify incidental findings.
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http://dx.doi.org/10.1186/s40001-018-0356-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284291PMC
December 2018

Performance and clinical impact of machine learning based lung nodule detection using vessel suppression in melanoma patients.

Clin Imaging 2018 Nov - Dec;52:328-333. Epub 2018 Sep 11.

University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Germany.

Purpose: To evaluate performance and the clinical impact of a novel machine learning based vessel-suppressing computer-aided detection (CAD) software in chest computed tomography (CT) of patients with malignant melanoma.

Materials And Methods: We retrospectively included consecutive malignant melanoma patients with a chest CT between 01/2015 and 01/2016. Machine learning based CAD software was used to reconstruct additional vessel-suppressed axial images. Three radiologists independently reviewed a maximum of 15 lung nodules per patient. Vessel-suppressed reconstructions were reviewed independently and results were compared. Follow-up CT examinations and clinical follow-up were used to assess the outcome. Impact of additional nodules on clinical management was assessed.

Results: In 46 patients, vessel-suppressed axial images led to the detection of additional nodules in 25/46 (54.3%) patients. CT or clinical follow up was available in 25/25 (100%) patients with additionally detected nodules. 2/25 (8%) of these patients developed new pulmonary metastases. None of the additionally detected nodules were found to be metastases. None of the lung nodules detected by the radiologists was missed by the CAD software. The mean diameter of the 92 additional nodules was 1.5 ± 0.8 mm. The additional nodules did not affect therapeutic management. However, in 14/46 (30.4%) of patients the additional nodules might have had an impact on the radiological follow-up recommendations.

Conclusion: Machine learning based vessel suppression led to the detection of significantly more lung nodules in melanoma patients. Radiological follow-up recommendations were altered in 30% of the patients. However, all lung nodules turned out to be non-malignant on follow-up.
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http://dx.doi.org/10.1016/j.clinimag.2018.09.001DOI Listing
January 2019

Prediction of outcome after aneurysmal subarachnoid haemorrhage using data from patient admission.

Eur Radiol 2018 Dec 12;28(12):4949-4958. Epub 2018 Jun 12.

University Düsseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Moorenstr. 5, D-40225, Düsseldorf, Germany.

Objectives: The pathogenesis leading to poor functional outcome after aneurysmal subarachnoid haemorrhage (aSAH) is multifactorial and not fully understood. We evaluated a machine learning approach based on easily determinable clinical and CT perfusion (CTP) features in the course of patient admission to predict the functional outcome 6 months after ictus.

Methods: Out of 630 consecutive subarachnoid haemorrhage patients (2008-2015), 147 (mean age 54.3, 66.7% women) were retrospectively included (Inclusion: aSAH, admission within 24 h of ictus, CTP within 24 h of admission, documented modified Rankin scale (mRS) grades after 6 months. Exclusion: occlusive therapy before first CTP, previous aSAH, CTP not evaluable). A random forests model with conditional inference trees was optimised and trained on sex, age, World Federation of Neurosurgical Societies (WFNS) and modified Fisher grades, aneurysm in anterior vs. posterior circulation, early external ventricular drainage (EVD), as well as MTT and T maximum, mean, standard deviation (SD), range, 75th quartile and interquartile range to predict dichotomised mRS (≤ 2; > 2). Performance was assessed using the balanced accuracy over the training and validation folds using 20 repeats of 10-fold cross-validation.

Results: In the final model, using 200 trees and the synthetic minority oversampling technique, median balanced accuracy was 84.4% (SD 0.7) over the training folds and 70.9% (SD 1.2) over the validation folds. The five most important features were the modified Fisher grade, age, MTT range, WFNS and early EVD.

Conclusions: A random forests model trained on easily determinable features in the course of patient admission can predict the functional outcome 6 months after aSAH with considerable accuracy.

Key Points: • Features determinable in the course of admission of a patient with aneurysmal subarachnoid haemorrhage (aSAH) can predict the functional outcome 6 months after the occurrence of aSAH. • The top five predictive features were the modified Fisher grade, age, the mean transit time (MTT) range from computed tomography perfusion (CTP), the WFNS grade and the early necessity for an external ventricular drainage (EVD). • The range between the minimum and the maximum MTT may prove to be a valuable biomarker for detrimental functional outcome.
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http://dx.doi.org/10.1007/s00330-018-5505-0DOI Listing
December 2018

Comparison of B versus B and B field inhomogeneity correction for glycosaminoglycan chemical exchange saturation transfer imaging.

MAGMA 2018 Oct 14;31(5):645-651. Epub 2018 May 14.

Department of Diagnostic and Interventional Radiology, University Dusseldorf Medical Faculty, 40225, Düsseldorf, Germany.

Purpose: The study compares glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging of intervertebral discs corrected for solely B inhomogeneities or both B and B inhomogeneities.

Methods: Lumbar intervertebral discs of 20 volunteers were examined with T-weighted and gagCEST imaging. Field inhomogeneity correction was performed with B correction only and with correction of both B and B. GagCEST effects measured by the asymmetric magnetization transfer ratio (MTR) and signal-to-noise ratio (SNR) were compared between both methods.

Results: Significant higher MTR and SNR values were obtained in the nucleus pulposus using B and B correction compared with B-corrected gagCEST. The GagCEST effect was significantly different in the nucleus pulposus compared with the annulus fibrosus for both methods.

Conclusion: The B and B field inhomogeneity correction method leads to an improved quality of gagCEST imaging in IVDs compared with only B correction.
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http://dx.doi.org/10.1007/s10334-018-0689-5DOI Listing
October 2018

Opportunistic Bone Density Measurement on Abdomen and Pelvis Computed Tomography to Predict Fracture Risk in Women Aged 50 to 64 Years Without Osteoporosis Risk Factors.

J Comput Assist Tomogr 2018 Sep/Oct;42(5):798-806

From the Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.

Objective: The aim of this study is to evaluate opportunistic vertebral bone density measurement in abdominal and pelvic computed tomography (CT) to predict future osteoporotic fracture in women aged 50 to 64 years without known osteoporosis risk factors.

Methods: Consecutive female patients 50 to 64 years old without osteoporosis risk factors with 2 CT examinations more than 10 years apart were included. Vertebral height and bone density in each vertebra from T10 to L5 were measured. Vertebral fractures were diagnosed on CT preformed 10 years after the original CT and through online medical records.

Results: Thirty (15%) of 199 patients developed osteoporotic fracture. Bone density was lower in patients who developed fractures compared with those who did not (P < 0.05). Development of osteoporotic fracture of any grade was predicted for patients having bone density less than 180 HU at L4 with sensitivity of 90% (95% confidence interval, 74%-97%) and specificity of 43% (95% confidence interval, 34%-50%).

Conclusions: Opportunistic bone density screening can identify women at elevated risk of developing fractures within 10 years.
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http://dx.doi.org/10.1097/RCT.0000000000000744DOI Listing
September 2018

Age-related apparent diffusion coefficients of lumbar vertebrae in healthy children at 1.5 T.

Pediatr Radiol 2018 07 13;48(7):1008-1012. Epub 2018 Apr 13.

Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225, Dusseldorf, Germany.

Background: Diffusion-weighted magnetic resonance imaging with apparent diffusion coefficient (ADC) calculation is important for detecting bone marrow pathologies.

Objective: To investigate age-related differences of lumbar vertebral body ADC to establish normal values for healthy children.

Materials And Methods: Forty-nine healthy children without any history of oncological or hematological diseases (10.2±4.7 years, range: 0-20 years) were included in this retrospective study. All magnetic resonance imaging (MRI) examinations were performed at 1.5 T and with similar scan parameters. The diffusion-weighted sequences were performed with b values of 50, 400 and 800 s/mm. ADC values were measured by placing regions of interest at three different levels within each lumbar vertebral body (L1 to L5). ADC values were analyzed for different age groups (0-2 years, 3-6 years, 7-11 years, 12-14 years, 15-20 years), for each vertebral and intravertebral level.

Results: The mean ADC of the whole study group was 0.60±0.09 × 10 mm/s. Children between the ages of 12 and 14 years had significantly higher ADC compared to the other age groups (P≤0.0003). ADC values were significantly higher in the 1st lumbar vertebral body compared to the other levels of the lumbar spine (P<0.005) with the exception of L5, and in the upper third of the vertebral bodies compared to the middle or lower thirds (P≤0.003).

Conclusion: The age-, vertebral- and intravertebral level-dependent differences in ADC suggest a varying composition and cellularity in different age groups and in different locations.
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http://dx.doi.org/10.1007/s00247-018-4119-7DOI Listing
July 2018

Tailoring CT Dose to Patient Size: Implementation of the Updated 2017 ACR Size-specific Diagnostic Reference Levels.

Acad Radiol 2018 12 23;25(12):1624-1631. Epub 2018 Mar 23.

University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Moorenstraße 5, 40225 Dusseldorf, Germany.

Rationale And Objectives: To use an automatic computed tomography (CT) dose monitoring system to analyze the institutional chest and abdominopelvic CT dose data as regards the updated 2017 American College of Radiology (ACR) diagnostic reference levels (DRLs) based on water-equivalent diameter (Dw) and size-specific dose estimates (SSDE) to detect patient-size subgroups in which CT dose can be optimized.

Materials And Methods: All chest CT examinations performed between July 2016 and April 2017 with and without contrast material, CT of the pulmonary arteries, and abdominopelvic CT with and without contrast material were included in this retrospective study. Dw and SSDE were automatically calculated for all scans using a previously validated in-house developed Matlab software and stored into our CT dose monitoring system. CT dose data were analyzed as regards the updated ACR DRLs (size groups: 21-25 cm, 25-29 cm, 29-33 cm, 33-37 cm, 37-41 cm). SSDE and volumetric computed tomography dose index (CTDIvol) were used as CT dose parameter.

Results: Overall, 30,002 CT examinations were performed in the study period, 3860 of which were included in the analysis (mean age 62.1 ± 16.4 years, Dw 29.0 ± 3.3 cm; n = 577 chest CT without contrast material, n = 628 chest CT with contrast material, n = 346 CT of chest pulmonary, n = 563 abdominopelvic CT without contrast material, n = 1746 abdominopelvic CT with contrast material). Mean SSDE and CTDIvol relative to the updated DRLs were 43.3 ± 26.4 and 45.1 ± 27.9% for noncontrast chest CT, 52.3 ± 23.1 and 52.0 ± 23.1% for contrast-enhanced chest CT, 68.8 ± 29.5 and 70.0 ± 31.0% for CT of pulmonary arteries, 41.9 ± 29.2 and 43.3 ± 31.3% for noncontrast abdominopelvic CT, and 56.8 ± 22.2 and 58.8 ± 24.4% for contrast-enhanced abdominopelvic CT. Lowest dose compared to the DRLs was found for the Dw group of 21-25 cm in noncontrast abdominopelvic CT (SSDE 30.4 ± 21.8%, CTDIvol 30.8 ± 21.4%). Solely the group of patients with a Dw of 37-41 cm undergoing noncontrast abdominopelvic CT exceeded the ACR DRL (SSDE 100.3 ± 59.0%, CTDIvol 107.1 ± 63.5%).

Conclusions: On average, mean SSDE and CTDIvol of our institutional chest and abdominopelvic CT protocols were lower than the updated 2017 ACR DRLs. Size-specific subgroup analysis revealed a wide variability of SSDE and CTDIvol across CT protocols and patient size groups with a transgression of DRLs in noncontrast abdominopelvic CT of large patients (Dw 37-41 cm).
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http://dx.doi.org/10.1016/j.acra.2018.03.005DOI Listing
December 2018

Heparin-bonded stent graft treatment for major visceral arterial injury after upper abdominal surgery.

Eur Radiol 2018 Aug 26;28(8):3221-3227. Epub 2018 Feb 26.

Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, 40225, Dusseldorf, Germany.

Purpose: To analyse technical success, complications, and short- and intermediate-term outcomes after heparin-bonded stent graft implantation for the treatment of major abdominal vessel injury after upper abdominal surgery.

Methods: This retrospective, IRB-approved analysis included 29 consecutive patients (female: n = 6, male: n = 23, mean age 65.9 ± 11.2 years). All patients underwent angiography and attempted heparin-bonded stent-graft implantation because of a major visceral arterial injury after upper abdominal surgery. Electronic clinical records, angiographic reports and imaging datasets were reviewed to assess technical success and complications. Telephone interviews were performed to obtain follow-up information and to estimate short- (> 30 days) and intermediate-term (> 90 days) outcomes.

Results: Successful stent graft placement was achieved in 82.8% (24/29). Peri-interventional complications were observed in 20.7% (6/29) and delayed, angiography-associated complications were observed in 34.5% (10/29) of the patients. Symptomatic re-bleeding occurred in 24.1% (7/29). Short-term survival (> 30 days) was 72.4% (21/29). Intermediate survival (> 90 days) was 37.9% (11/29).

Conclusion: Treatment of major vascular injuries with heparin-bonded stent grafts is feasible with a high technical success rate. However, survival depends on the underlying surgical condition, making interdisciplinary patient management mandatory.

Key Points: • Stent graft implantation is challenging, but has a high technical success rate. • Complications are frequent but surgical conversion is rarely necessary. • Survival depends on the underlying surgical condition causing the vascular injury. • Interdisciplinary management is crucial for the survival of these patients.
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http://dx.doi.org/10.1007/s00330-017-5288-8DOI Listing
August 2018

Radiologists' Experience With Patient Interactions in the Era of Open Access of Patients to Radiology Reports.

J Am Coll Radiol 2018 Nov 2;15(11):1573-1579. Epub 2018 Jan 2.

Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts. Electronic address:

Purpose: The aim of this study was to evaluate radiologists' experiences with patient interactions in the era of open access of patients to radiology reports.

Methods: This prospective, nonrandom survey of staff and trainee radiologists (n = 128) at a single large academic institution was performed with approval from the institutional review board with a waiver of the requirement to obtain informed consent. A multiple-choice questionnaire with optional free-text comments was constructed with an online secure platform (REDCap) and distributed via departmental e-mail between June 1 and July 31, 2016. Participation in the survey was voluntary and anonymous, and responses were collected and aggregated via REDCap. Statistical analysis of categorical responses was performed with the χ test, with statistical significance defined as P < .05.

Results: Almost three-quarters of surveys (73.4% [94 of 128]) were completed. Staff radiologists represented 54.3% of survey respondents (51 of 94) and trainees 45.7% (43 of 94). Most respondents (78.7% [74 of 94]) found interactions with patients to be a satisfying experience. More than half of radiologists (54.3% [51 of 94]) desired more opportunities for patient interaction, with no significant difference in the proportion of staff and trainee radiologists who desired more patient interaction (56.9% [29 of 51] versus 51.2% [22 of 43], P = .58). Staff radiologists who specialized in vascular and interventional radiology and mammography were significantly more likely to desire more patient interaction compared with other specialists (77.8% [14 of 18] versus 45.5% [15 of 33], P = .03). Only 4.2% of radiologists (4 of 94) found patient interactions to be detrimental to normal workflow, with 19.1% of radiologists (18 of 94) reporting having to spend more than 15 min per patient interaction.

Conclusions: Most academic staff and trainee radiologists would like to have more opportunities for patient interaction and consider patient interaction rarely detrimental to workflow.
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http://dx.doi.org/10.1016/j.jacr.2017.10.032DOI Listing
November 2018

Institutional computed tomography diagnostic reference levels based on water-equivalent diameter and size-specific dose estimates.

J Radiol Prot 2018 Jun 20;38(2):536-548. Epub 2017 Dec 20.

University Düsseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Düsseldorf, Germany.

Size-specific institutional diagnostic reference levels (DRLs) were generated for chest and abdominopelvic computed tomography (CT) based on size-specific dose estimates (SSDEs) and depending on patients' water-equivalent diameter (Dw). 1690 CT examinations were included in the IRB-approved retrospective study. SSDEs based on the mean water-equivalent diameter of the entire scan volume were calculated automatically. SSDEs were analyzed for different patient sizes and institutional DRLs (iDRLS; 75% percentiles) based on Dw and SSDEs were generated. iDRLs were compared to the national DRLs. Mean volumetric computed tomography dose index (CTDIvol), Dw and SSDEs for all 1690 CT examinations were 7.2 ± 4.0 mGy (0.84-47.9 mGy), 29.0 ± 3.4 cm and 8.5 ± 3.8 mGy (1.2-37.7 mGy), respectively. Overall, the mean SSDEs of all CT examinations were higher than the CTDIvol in chest CT, abdominopelvic CT and upper abdominal CT, respectively (p < 0.001 for all). There was a strong linear correlation between Dw and SSDEs in chest (R = 0.66), abdominopelvic (R = 0.98) and upper abdominal CT (R = 0.96) allowing for the implementation of size-specific institutional DRLs based on SSDEs and patients' Dw. We generated size-specific, Dw-dependent institutional DRLs based on SSDEs, which allow for easier and more comprehensive analyses of CT radiation exposure. Our results indicate that implementation of SSDEs into national DRLs may be beneficial.
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http://dx.doi.org/10.1088/1361-6498/aaa32cDOI Listing
June 2018

Dual-phase hybrid F-Fluoride Positron emission tomography/MRI in ankylosing spondylitis: Investigating the link between MRI bone changes, regional hyperaemia and increased osteoblastic activity.

J Med Imaging Radiat Oncol 2018 Jun 25;62(3):313-319. Epub 2017 Oct 25.

Medical Faculty, Department of Diagnostic and Interventional Radiology, University of Dusseldorf, Dusseldorf, Germany.

Introduction: Focal F-Fluoride uptake on blood-pool phase PET represents regional hyperaemia, while it indicates osteoblastic activity on mineralization phase PET. This study investigates the link between regional hyperaemia and osteoblastic activity in inflammatory and chronic lesions of ankylosing spondylitis (AS) of the sacroiliac joints (SIJ) using dual-phase F-Fluoride PET/MRI.

Methods: Thirteen patients (six men, seven women, age: 37 ± 10 years) with active AS prospectively underwent dual-phase F-Fluoride PET/MRI. Blood-pool phase PET was acquired 6 min and mineralization phase PET 40 min after injection of 158 ± 8 MBq F-Fluoride. SIJ quadrants (SQ) were assessed regarding inflammatory lesions represented by bone marrow oedema (BME), chronic AS lesions such as erosion, fat deposition (FD), sclerosis and ankylosis on MRI, and regarding focal F-Fluoride uptake on both PET datasets. Image quality (IQ) of both PET datasets and MRI was evaluated using a 4-point Likert scale.

Results: Of 104 SQ, there were 63.4% SQ with FD, 42.3% SQ with BME, 26.9% SQ with erosions, 26% SQ with sclerosis and 10.6% SQ with ankylosis. BME alone was associated with focal F-Fluoride uptake in 63.6% SQ on blood-pool phase and 90.9% SQ on mineralization phase F-Fluoride PET/MRI. Instead, FD, erosion, sclerosis, ankylosis were not associated with focal F-Fluoride uptake on either blood-pool or mineralization phase F-Fluoride PET/MRI. SQ showing BME alone or a combination of BME and chronic AS lesions had a significantly higher percentage of focal F-Fluoride uptake on blood-pool phase and mineralization phase PET/MRI than SQ showing AS lesions without BME (P < 0.001). Both F-Fluoride PET datasets provided high IQ, albeit IQ of mineralization phase PET was superior to blood-pool phase PET (P < 0.001).

Conclusion: Dual-phase F-Fluoride PET/MRI of the SIJ showed that inflammatory rather than chronic AS lesions are associated with regional hyperaemia and osteoblastic activity.
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http://dx.doi.org/10.1111/1754-9485.12687DOI Listing
June 2018

Accuracy of Size-Specific Dose Estimate Calculation from Center Slice in Computed Tomography.

Radiat Prot Dosimetry 2018 02;178(3):343

Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Moorenstraße 5, 40 225 Düsseldorf, Germany.

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http://dx.doi.org/10.1093/rpd/ncx119DOI Listing
February 2018

Ovarian Cancer: Prevalence in Incidental Simple Adnexal Cysts Initially Identified in CT Examinations of the Abdomen and Pelvis.

Radiology 2018 01 14;286(1):196-204. Epub 2017 Sep 14.

From the Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215.

Purpose To evaluate the rate of malignancy in incidentally detected simple adnexal cysts at computed tomography (CT) to determine if simple-appearing cysts require follow-up. Materials and Methods In this HIPAA-compliant, institutional review board-approved retrospective cohort study, an institutional database was searched for abdominal and pelvic CT studies performed between June 2003 and December 2010 in women reported to have adnexal cysts. Adnexal cyst characterization was determined by prospective report description as well as image review by a research fellow and by a fellowship-trained abdominal radiologist for examinations with disagreement between the original report and the research fellow's assessment. Patients with known ovarian cysts or ovarian cancer at time of the index CT examination were excluded. Clinical outcome was assessed by using follow-up imaging studies, medical records, and the state cancer registry. Benign outcome was determined by benign findings at surgery, a decrease in size or resolution of a simple-appearing cyst at follow-up imaging, or stability of the cyst for at least 1 year. Descriptive statistics and 95% confidence intervals (CIs) were calculated. Results Among 42 111 women who underwent abdominal and pelvic CT examinations in the study period, 2763 (6.6%; 95% CI: 6.3%, 6.8%) (mean age, 48.1 years ± 18.1; range, 15-102 years) had a newly detected finding of ovarian cyst described in the body or impression section of the report. Median cyst size was 3.1 cm (range, 0.8-20.0 cm). Eighteen (0.7%; 95% CI: 0.4%, 1.0%) of 2763 patients were found to have ovarian cancer after an average follow-up of 5.1 years ± 3.8 (range, 0-12.8 years). None (95% CI: 0%, 0.4%) of 1031 women with simple-appearing cysts were given a diagnosis of ovarian cancer. This included none (95% CI: 0%, 0.4%) of 904 women with simple-appearing cysts with an adequate reference standard for benign outcome. Conclusion The prevalence of previously unknown adnexal cysts at CT was 6.6%, with an ovarian cancer rate of 0.7% (95% CI: 0.4%, 1.0%). All simple-appearing cysts were benign (95% CI: 99.6%, 100%). RSNA, 2017 Online supplemental material is available for this article.
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http://dx.doi.org/10.1148/radiol.2017162139DOI Listing
January 2018

Iterative metal artefact reduction (MAR) in postsurgical chest CT: comparison of three iMAR-algorithms.

Br J Radiol 2017 Nov 22;90(1079):20160778. Epub 2017 Aug 22.

1 Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, Dusseldorf, Germany.

Objectives: The purpose of this study was to evaluate the impact of three novel iterative metal artefact (iMAR) algorithms on image quality and artefact degree in chest CT of patients with a variety of thoracic metallic implants.

Methods: 27 postsurgical patients with thoracic implants who underwent clinical chest CT between March and May 2015 in clinical routine were retrospectively included. Images were retrospectively reconstructed with standard weighted filtered back projection (WFBP) and with three iMAR algorithms (iMAR-Algo1 = Cardiac algorithm, iMAR-Algo2 = Pacemaker algorithm and iMAR-Algo3 = ThoracicCoils algorithm). The subjective and objective image quality was assessed.

Results: Averaged over all artefacts, artefact degree was significantly lower for the iMAR-Algo1 (58.9 ± 48.5 HU), iMAR-Algo2 (52.7 ± 46.8 HU) and the iMAR-Algo3 (51.9 ± 46.1 HU) compared with WFBP (91.6 ± 81.6 HU, p < 0.01 for all). All iMAR reconstructed images showed significantly lower artefacts (p < 0.01) compared with the WFPB while there was no significant difference between the iMAR algorithms, respectively. iMAR-Algo2 and iMAR-Algo3 reconstructions decreased mild and moderate artefacts compared with WFBP and iMAR-Algo1 (p < 0.01).

Conclusion: All three iMAR algorithms led to a significant reduction of metal artefacts and increase in overall image quality compared with WFBP in chest CT of patients with metallic implants in subjective and objective analysis. The iMARAlgo2 and iMARAlgo3 were best for mild artefacts. IMARAlgo1 was superior for severe artefacts. Advances in knowledge: Iterative MAR led to significant artefact reduction and increase image-quality compared with WFBP in CT after implementation of thoracic devices. Adjusting iMAR-algorithms to patients' metallic implants can help to improve image quality in CT.
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http://dx.doi.org/10.1259/bjr.20160778DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5963368PMC
November 2017

Split-Bolus Injection Producing Simultaneous Late Arterial and Portal Venous Phases in CT Enterography: Preliminary Results.

AJR Am J Roentgenol 2017 Nov 16;209(5):1056-1063. Epub 2017 Aug 16.

1 Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215.

Objective: The purpose of this article is to evaluate the image quality and added value of split-bolus contrast agent injection combining late arterial and portal venous phases compared with single-bolus contrast agent injection late arterial phase CT enterography.

Materials And Methods: Consecutive patients who underwent CT enterography before and after implementation of a single-bolus CT enterography protocol were included. Attenuation and contrast-to-noise ratio (CNR) were assessed by ROI measurements of the bowel wall and arterial and venous structures. Subjective enhancement of the bowel wall (1, arterial; 2, mucosal; 3, transmural; 4, transmural with mucosal hyperenhancement) and bowel abnormalities were assessed by two independent readers. MR enterography examinations, endoscopy reports, and surgery reports within 30 days after CT enterography were used to produce a composite outcome.

Results: Sixty-six patients were included in our study: 33 (mean [± SD] age, 46.0 ± 19.8 years) who underwent split-bolus CT enterography and 33 (mean age, 49.9 ± 19.0 years) who underwent single-bolus CT enterography. Bowel wall attenuation and CNR were higher for split-bolus CT enterography than for single-bolus CT enterography at 120 kVp (enhancement, 98.7 ± 23.1 HU vs 85.1 ± 23.3 HU; CNR, 6.4 ± 2.5 vs 4.4 ± 2.3; p < 0.01). Subjective ratings of bowel wall enhancement were higher with the split-bolus CT enterography than the single-bolus CT enterography (2.6 ± 0.8 vs 2.3 ± 0.6; p < 0.001). Split-bolus CT enterography led to a higher detection rate of mucosal hyperenhancement than did single-bolus CT enterography in patients with active inflammatory bowel disease (100.0% [7/7; 95% CI, 59.0-100.0%] vs 33.3% [2/6; 95% CI, 4.3-77.7%]; p = 0.02), whereas both protocols had a specificity of 100.0% (9/9).

Conclusion: Split-bolus CT enterography led to improved CNR (47%) compared with single-bolus CT enterography and significantly increased the detection rate of mucosal hyperenhancement in patients with active inflammatory bowel disease.
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http://dx.doi.org/10.2214/AJR.17.18034DOI Listing
November 2017