The burden of abdominal pain after bariatric surgery in terms of diagnostic testing: the OPERATE study.

BACKGROUND: Abdominal pain after bariatric surgery (BS) is frequently observed. Despite numerous diagnostic tests, the cause of abdominal pain is not always found. OBJECTIVES: To quantify type and number of diagnostic tests performed in patients with abdominal pain after BS and evaluate the burden and their yield in the diagnostic process. SETTING: A bariatric center in the Netherlands. METHODS: In this prospective study, we included patients who presented with abdominal pain after BS between December 1, 2020, and December 1, 2021. All diagnostic tests and reoperations performed during one episode of abdominal pain were scored using a standardized protocol. RESULTS: A total of 441 patients were included; 401 (90.9%) were female, median time after BS was 37.0 months (IQR, 11.0-66.0) and mean percentage total weight loss was 31.41 (SD, 10.53). In total, 715 diagnostic tests were performed, of which 355 were abdominal CT scans, 155 were ultrasounds, and 106 were gastroscopies. These tests yielded a possible explanation for the pain in 40.2% of CT scans, 45.3% of ultrasounds, and 34.7% of gastroscopies. The diagnoses of internal herniation, ileus, and nephrolithiasis generally required only 1 diagnostic test, whereas patients with anterior cutaneous nerve entrapment syndrome, irritable bowel syndrome, and constipation required several tests before diagnosis. Even after several negative tests, a diagnosis was still found in the subsequent test: 86.7% of patients with 5 or more tests had a definitive diagnoses. Reoperations were performed in 37.2% of patients. CONCLUSION: The diagnostic burden in patients with abdominal pain following BS is high. The most frequently performed diagnostic test is an abdominal CT scan, yielding the highest number of diagnoses in these patients.

A Prospective Study on the Diagnoses for Abdominal Pain After Bariatric Surgery: The OPERATE Study.

PURPOSE: Long-term follow-up after bariatric surgery (BS) reveals high numbers of patients with abdominal pain that often remains unexplained. The aim of this prospective study was to give an overview of diagnoses for abdominal pain, percentage of unexplained complaints, number and yield of follow-up visits, and time to establish a diagnosis. MATERIALS AND METHODS: Patients who visited the Spaarne Gasthuis Hospital, The Netherlands, between December 2020 and December 2021 for abdominal pain after BS, were eligible and followed throughout the entire episode of abdominal pain. Distinction was made between presumed and definitive diagnoses. RESULTS: The study comprised 441 patients with abdominal pain; 401 (90.9%) females, 380 (87.7%) had Roux-en-Y gastric bypass, mean (SD) % total weight loss was 31.4 (10.5), and median (IQR) time after BS was 37.0 (11.0-66.0) months. Most patients had 1-5 follow-up visits. Readmissions and reoperations were present in 212 (48.1%) and 164 (37.2%) patients. At the end of the episode, 88 (20.0%) patients had a presumed diagnosis, 183 (41.5%) a definitive diagnosis, and 170 (38.5%) unexplained complaints. Most common definitive diagnoses were cholelithiasis, ulcers, internal herniations, and presumed diagnoses irritable bowel syndrome (IBS), anterior cutaneous nerve entrapment syndrome, and constipation. Median (IQR) time to presumed diagnoses, definitive diagnoses, or unexplained complaints was 16.0 (3.8-44.5), 2.0 (0.0-31.5), and 13.5 (1.0-53.8) days (p < 0.001). Patients with IBS more often had unexplained complaints (OR 95%CI: 4.457 [1.455-13.654], p = 0.009). At the end, 71 patients (16.1%) still experienced abdominal pain. CONCLUSION: Over a third of abdominal complaints after BS remains unexplained. Most common diagnoses were cholelithiasis, ulcers, and internal herniations.

An Magnetic Resonance Imaging-directed Targeted-plus-perilesional Biopsy Approach for Prostate Cancer Diagnosis: "Less Is More".

Background: Considering that most men benefit diagnostically from increased sampling of index lesions, limiting systematic biopsy (SBx) to the region around the index lesion could potentially minimize overdetection while maintaining the detection of clinically significant prostate cancer (csPCa). Objective: To evaluate the diagnostic performance of a hypothetical magnetic resonance imaging (MRI)-directed targeted-plus-perilesional biopsy approach. Design setting and participants: This single-center, retrospective analysis of prospectively generated data included all biopsy-naïve men with unilateral MRI-positive lesions (Prostate Imaging Reporting and Data System category ≥3), undergoing both MRI-directed targeted biopsies and SBx. Grade group 2-5 cancers were considered csPCa. Outcome measurements and statistical analysis: The diagnostic performance of a targeted-plus-perilesional biopsy approach was compared with that of a targeted-plus-systematic biopsy approach. The primary outcome was the detection of csPCa. Secondary outcomes included the detection of clinically insignificant prostate cancer (ciPCa) and the number of total biopsy cores. Results and limitations: A total of 235 men were included in the analysis; csPCa and ciPCa were detected, respectively, in 95 (40.4%) and 86 (36.6%) of these 235 men. A targeted-plus-perilesional biopsy approach would have detected 92/95 (96.8%; 95% confidence interval [CI] 91.0-99.3%) csPCa cases. At the same time, detection of systematically found ciPCa would be reduced by 11/86 (12.8%; 95% CI 6.6-21.7%). If a targeted-plus-perilesional biopsy approach would have been performed, the number of biopsy cores per patient would have been reduced significantly (a mean difference of 5.2; 95% CI 4.9-5.6, p < 0.001). Conclusions: An MRI-directed targeted-plus-perilesional biopsy approach detected almost all csPCa cases, while limiting overdiagnosis and reducing the number of biopsy cores. Prospective clinical trials are needed to substantiate the withholding of nonperilesional SBx in men with unilateral lesion(s) on MRI. Patient summary: Limiting systematic biopsies to the proximity of the suspicious area on magnetic resonance imaging helps detect an equivalent number of aggressive cancers and fewer indolent cancers. These findings may help patients and physicians choose the best biopsy approach.

Fibrosis and MAGNIFI-CD Activity Index at Magnetic Resonance Imaging to Predict Treatment Outcome in Perianal Fistulizing Crohn's Disease Patients.

BACKGROUND AND AIMS: Characteristic magnetic resonance imaging [MRI] features associated with long-term perianal fistula closure are still being discussed. This study evaluated the predictive value of degree of fibrosis and disease activity (MAGNIFI-CD index) at MRI for long-term clinical closure of Crohn's perianal fistulas. METHODS: Crohn's disease [CD] patients treated with surgical closure following anti-tumour necrosis factor [anti-TNF] induction or anti-TNF alone for high perianal fistulas as part of a patient preference randomized controlled trial [PISA-II] between 2013 and 2020 with a post-treatment MRI and long-term clinical follow-up data were retrospectively included. Two radiologists scored the degree of fibrosis and MAGNIFI-CD index at pre- and post-treatment MRI. The accuracy of post-treatment MRI findings in predicting long-term clinical closure [12 months after the MRI] was evaluated using receiver operating characteristics [ROC] analysis. RESULTS: Fifty patients were included: 31 female, median age 33 years (interquartile range [IQR] 26-45). Fourteen patients showed a 100% fibrotic fistula at post-treatment MRI, all of which had long-term clinical closure. Median MAGNIFI-CD index at post-treatment MRI was 0 [IQR 0-5] in 25 patients with long-term clinical closure and 16 [IQR 10-20] in 25 patients without. ROC analysis showed an area under the curve of 0.90 (95% confidence interval [CI] 0.82-0.99) for degree of fibrosis and 0.95 [95% CI 0.89-1.00] for the MAGNIFI-CD index, with a Youden cut-off point of 6 [91% specificity, 87% sensitivity]. CONCLUSIONS: Degree of fibrosis and MAGNIFI-CD index at post-treatment MRI are accurate in predicting long-term clinical closure and seem valuable in follow-up of perianal CD. A completely fibrotic tract at MRI is a robust indicator for long-term fistula closure. EUDRACT: 2013-002932-25 and 2018-002064-15.

Fasted and fed small bowel motility patterns at cine-MRI in chronic intestinal pseudo-obstruction.

BACKGROUND: Chronic intestinal pseudo-obstruction (CIPO) is a severe intestinal motility disorder of which the pathophysiology is largely unknown. This study aimed at gaining insight in fasted and fed small bowel motility in CIPO patients using cine-MRI with caloric stimulation. METHODS: Eight adult patients with manometrically confirmed CIPO were prospectively included. Patients underwent a cine-MRI protocol after an overnight fast, comprising fasting-state scans and scans after ingestion of a meal (Nutridrink, 300 kcal). Small bowel motility was quantified resulting in a motility score in arbitrary units (AU) and visually assessed by three radiologists. Findings were compared with those in 16 healthy volunteers. KEY RESULTS: Motility scores (median, IQR) in CIPO patients were 0.21 (0.15-0.30) in the fasting state and 0.23 (0.15-0.27) directly postprandially. In healthy volunteers, corresponding motility scores were 0.15 (0.13-0.18) and 0.22 (0.19-0.25), respectively. The postprandial change in motility score was +1% (-19 to +21%) in CIPO and +39% (+23 to +50%) in healthy volunteers (p = 0.001*). Visual analysis revealed increased small bowel contractility in four, normal in two, and decreased in two CIPO patients. CONCLUSIONS & INFERENCES: Surprisingly, we found hyperactive small bowel motility in half of the CIPO patients, suggestive of uncoordinated motility. A wide variation in motility patterns was observed, both higher, lower, and comparable contractility compared with healthy subjects. No clear postprandial activation was seen in patients. Cine-MRI helps to gain insight in this complex disease and can potentially impact treatment decisions in the future.

A prospective study comparing water only with positive oral contrast in patients undergoing abdominal CT scan.

Consecutive adults scheduled to undergo abdominal CT with oral contrast were asked to choose between 1000 ml water only or positive oral contrast (50 ml Télébrix-Gastro diluted in 950 ml water). Two abdominal radiologists independently reviewed each scan for image quality of the abdomen, the diagnostic confidence per system (gastrointestinalsystem/organs/peritoneum/retroperitoneum/lymph nodes) and overall diagnostic confidence to address the clinical question (not able/partial able/fully able). Radiation exposure was extracted from dose reports. Differences between both groups were evaluated by Student's t-test, Mann-Whitney-U-test or chi-square-test. Of the 320participants, 233chose water only. All baseline characteristics, image quality of the abdomen and the diagnostic confidence of the organs were comparable between groups and both observers. Diagnostic confidence in the water only group was more commonly scored as less than good by observer1. The results were as follows: the gastrointestinal system(18/233vs1/87; p = 0.031), peritoneum (21/233vs1/87; p = 0.012), retroperitoneum (11/233vs0/87; p = 0.040) and lymph nodes (11/233vs0/87; p = 0.040). These structures were scored as comparable between both groups by observer2. The diagnostic confidence to address the clinical question could be partially addressed in 6/233 vs 0/87 patients (p = 0.259). The water only group showed a tendency towards less radiation exposure. In summary, most scan ratings were comparable between positive contrast and water only, but slightly favored positive oral contrast for one reader for some abdominal structures. Therefore, water only can replace positive oral contrast in the majority of the outpatients scheduled to undergo an abdominal CT.

Evaluation of the modified Van Assche index for assessing response to anti-TNF therapy with MRI in perianal fistulizing Crohn's disease.

BACKGROUND: Structured evaluation of magnetic resonance imaging (MRI) is important to guide clinical decisions of perianal fistulas in Crohn's disease (CD) patients. PURPOSE: To evaluate the recently developed modified Van Assche index to assess clinical responses to anti-tumor necrosis factor (TNF) therapy in patients with perianal fistulizing CD. METHODS: A search of medical records identified patients with fistulizing perianal CD who underwent baseline and follow-up MRI while receiving anti-TNF treatment. Patients were divided into clinical responders and non-responders based on physician's assessment. MRI-scans were scored using the original and modified Van Assche index and scores between baseline and follow-up were compared within clinical responders and non-responders. RESULTS: Thirty cases were included (48% female, median age 27 years). Clinical responders (n = 16) had a median modified Van Assche score of 9.6 (IQR 5.8-12.7) at baseline and 5.8 (IQR 3.5-8.5) at follow-up (p = 0.008). In non-responders (n = 14), corresponding scores were 7.7 (IQR 5.8-13.5) and 8.2 (IQR 5.8-11.5) (p = 0.624). In clinical responders, 6/16 showed no drop in modified Van Assche score at follow-up. Scores obtained with the original Van Assche index dropped between baseline and follow-up in clinical responders (13.0 vs. 9.6, p = 0.011), whereas no decrease was observed in non-responders (11.5 vs. 11.5, p = 0.324). CONCLUSIONS: While the modified Van Assche index overall decreases significantly in patients with perianal fistulas responding to anti-TNF treatment, one third of responders had unaltered scores at follow-up. Also, outcomes were comparable to the original Van Assche index. Further optimization of the modified Van Assche index is needed before application in larger studies.

Staging of Anal Cancer: Role of MR Imaging.

Anal cancer is a relatively rare malignancy. Treatment consists of chemoradiation and most patients achieve a complete response. Local evaluation of the T and N stage is performed by MR imaging. Whole-body staging with 18F-fluorodesoxyglucose positron emission tomography computed tomography scans or computed tomography scans is used to detect metastases. T stage is based on tumor size or invasion of organs. N stage is based on nodal location. After chemoradiation, clinical evaluation and MR imaging is used to assess tumor and nodal response. Maximal response is achieved 6 months after chemoradiation. Beware of development of anal cancer in perianal fistulas.

Comparison of contrast-enhanced and diffusion-weighted MRI in assessment of the terminal ileum in Crohn's disease patients.

PURPOSE: The purpose of the study was to compare the performance of contrast-enhanced (CE)-MRI and diffusion-weighted imaging (DW)-MRI in grading Crohn's disease activity of the terminal ileum. METHODS: Three readers evaluated CE-MRI, DW-MRI, and their combinations (CE/DW-MRI and DW/CE-MRI, depending on which protocol was used at the start of evaluation). Disease severity grading scores were correlated to the Crohn's Disease Endoscopic Index of Severity (CDEIS). Diagnostic accuracy, severity grading, and levels of confidence were compared between imaging protocols and interobserver agreement was calculated. RESULTS: Sixty-one patients were included (30 female, median age 36). Diagnostic accuracy for active disease for CE-MRI, DW-MRI, CE/DW-MRI, and DW/CE-MRI ranged between 0.82 and 0.85, 0.75 and 0.83, 0.79 and 0.84, and 0.74 and 0.82, respectively. Severity grading correlation to CDEIS ranged between 0.70 and 0.74, 0.66 and 0.70, 0.69 and 0.75, and 0.67 and 0.74, respectively. For each reader, CE-MRI values were consistently higher than DW-MRI, albeit not significantly. Confidence levels for all readers were significantly higher for CE-MRI compared to DW-MRI (P < 0.001). Further increased confidence was seen when using combined imaging protocols. CONCLUSIONS: There was no significant difference of CE-MRI and DW-MRI in determining disease activity, but the higher confidence levels may favor CE-MRI. DW-MRI is a good alternative in cases with relative contraindications for the use of intravenous contrast medium.

Comparison of MRI Activity Scoring Systems and Features for the Terminal Ileum in Patients With Crohn Disease.

OBJECTIVE: The purpose of this study was to evaluate four previously validated MRI activity scoring systems for diagnosis and grading of Crohn disease (CD) in the terminal ileum against an endoscopic and histopathologic reference standard. SUBJECTS AND METHODS: Ethics approval and written informed consent were obtained. Subjects with known or suspected CD were prospectively recruited between December 2011 and August 2014. Each patient underwent MRI and ileocolonoscopy with terminal ileum biopsies. Four MRI scoring systems (Magnetic Resonance Index of Activity [MaRIA], Clermont score, London score, and Crohn disease MRI Index) and component features were applied by two observers and correlated to the Crohn disease endoscopic index of severity (CDEIS, 0-44) and histopathologic endoscopic acute inflammation score (0-6). Interobserver agreement (weighted kappa and intraclass correlation coefficient [ICC]) and diagnostic accuracy for active and ulcerating endoscopic or histopathologic disease were evaluated. RESULTS: Ninety-eight patients (median age, 32 years old; 55 women, 43 men) were included. All four scoring systems showed good interobserver agreement (ICC = 0.70-0.78), moderate-to-strong correlation to CDEIS (r = 0.57-0.67) and weak-to-moderate correlation to endoscopic acute inflammation score (r = 0.38-0.49). Scoring systems' diagnostic accuracy for active and ulcerating endoscopic disease ranged from 73% to 78% and 71% to 76%, respectively, whereas for active histopathologic disease accuracy ranged from 65% to 72%. Between the scoring systems, no significant differences were found for both observers regarding interobserver agreement, correlation coefficients, and diagnostic accuracy. CONCLUSION: All scoring systems were comparable in terms of interobserver agreement, correlation to the endoscopic and histopathologic reference standard, and diagnostic accuracy. The London score, MaRIA, and Clermont score have the additional benefit of having validated cutoff values for both active and ulcerating endoscopic disease.

Quantified Terminal Ileal Motility during MR Enterography as a Biomarker of Crohn Disease Activity: Prospective Multi-Institution Study.

Purpose To evaluate the accuracy of MRI-quantified small bowel motility for Crohn disease activity against endoscopic and histopathologic reference standards. Materials and Methods For this prospective study, 82 participants (median age, 31 years; range, 16 to 70 years; 42 males [median age, 31 years; range, 17 to 70 years] and 40 females [median age, 31 years; range, 16 to 63 years) underwent colonoscopy and MR enterography within 14 days (from October 2011 to March 2014) at two centers. The Crohn disease endoscopic index of severity (CDEIS), histopathologic activity score (endoscopic biopsy acute histologic inflammatory score [EAIS]), and MR index of activity (MaRIA) were scored in the terminal ileum. Terminal ileal motility was quantified by using an image registration based-motility assessment algorithm (hereafter, Motility). Sensitivity and specificity of Motility (˂0.3 arbitrary units) and MaRIA (≥7 and ≥11) for disease activity (CDEIS ≥4 or EAIS ≥1) were compared by using the McNemar test. Receiver operating characteristic curves were constructed and areas under the curve were compared. Motility was correlated with reference standards by using Spearman rank estimates. Results Terminal ileal Motility was negatively correlated with EAIS (r =-0.61; 95% confidence interval [CI]: 0.7, -0.5) and CDEIS (r = -0.59; 95% CI: 0.7, -0.4). With CDEIS as the standard of reference, Motility had higher sensitivity than did MaRIA (≥11) (93% vs 78%, respectively; P = .03), but lower specificity (61% vs 81%, respectively; P = .04). With EAIS as the standard of reference, Motility had higher sensitivity than did MaRIA (≥7) (92% vs 75%, respectively; P = .03) but similar specificity (71% vs 74%, respectively; P >.99). The area under the receiver operating characteristic curve for Motility was 0.86 and 0.87 with CDEIS and EAIS as the standard of reference, respectively. Conclusion The terminal ileal Motility score showed good agreement with endoscopic and histopathologic activity in Crohn disease. © RSNA, 2018 Online supplemental material is available for this article.

Semiautomatic Assessment of the Terminal Ileum and Colon in Patients with Crohn Disease Using MRI (the VIGOR++ Project).

RATIONALE AND OBJECTIVES: The objective of this study was to develop and validate a predictive magnetic resonance imaging (MRI) activity score for ileocolonic Crohn disease activity based on both subjective and semiautomatic MRI features. MATERIALS AND METHODS: An MRI activity score (the "virtual gastrointestinal tract [VIGOR]" score) was developed from 27 validated magnetic resonance enterography datasets, including subjective radiologist observation of mural T2 signal and semiautomatic measurements of bowel wall thickness, excess volume, and dynamic contrast enhancement (initial slope of increase). A second subjective score was developed based on only radiologist observations. For validation, two observers applied both scores and three existing scores to a prospective dataset of 106 patients (59 women, median age 33) with known Crohn disease, using the endoscopic Crohn's Disease Endoscopic Index of Severity (CDEIS) as a reference standard. RESULTS: The VIGOR score (17.1 × initial slope of increase + 0.2 × excess volume + 2.3 × mural T2) and other activity scores all had comparable correlation to the CDEIS scores (observer 1: r = 0.58 and 0.59, and observer 2: r = 0.34-0.40 and 0.43-0.51, respectively). The VIGOR score, however, improved interobserver agreement compared to the other activity scores (intraclass correlation coefficient = 0.81 vs 0.44-0.59). A diagnostic accuracy of 80%-81% was seen for the VIGOR score, similar to the other scores. CONCLUSIONS: The VIGOR score achieves comparable accuracy to conventional MRI activity scores, but with significantly improved reproducibility, favoring its use for disease monitoring and therapy evaluation.

Semi-automatic bowel wall thickness measurements on MR enterography in patients with Crohn's disease.

OBJECTIVE: To evaluate a semi-automatic method for delineation of the bowel wall and measurement of the wall thickness in patients with Crohn's disease. METHODS: 53 patients with suspected or proven Crohn's disease were selected. Two radiologists independently supervised the delineation of regions with active Crohn's disease on MRI, yielding manual annotations (Ano1, Ano2). Three observers manually measured the maximal bowel wall thickness of each annotated segment. An active contour segmentation approach semi-automatically delineated the bowel wall. For each active region, two segmentations (Seg1, Seg2) were obtained by independent observers, in which the maximum wall thickness was automatically determined. The overlap between (Seg1, Seg2) was compared with the overlap of (Ano1, Ano2) using Wilcoxon's signed rank test. The corresponding variances were compared using the Brown-Forsythe test. The variance of the semi-automatic thickness measurements was compared with the overall variance of manual measurements through an F-test. Furthermore, the intraclass correlation coefficient (ICC) of semi-automatic thickness measurements was compared with the ICC of manual measurements through a likelihood-ratio test. RESULTS: Patient demographics: median age, 30 years; interquartile range, 25-38 years; 33 females. The median overlap of the semi-automatic segmentations (Seg1 vs Seg2: 0.89) was significantly larger than the median overlap of the manual annotations (Ano1 vs Ano2: 0.72); p = 1.4 × 10-5. The variance in overlap of the semi-automatic segmentations was significantly smaller than the variance in overlap of the manual annotations (p = 1.1 × 10-9). The variance of the semi-automated measurements (0.46 mm2) was significantly smaller than the variance of the manual measurements (2.90 mm2, p = 1.1 × 10-7). The ICC of semi-automatic measurement (0.88) was significantly higher than the ICC of manual measurement (0.45); p = 0.005. CONCLUSION: The semi-automatic technique facilitates reproducible delineation of regions with active Crohn's disease. The semi-automatic thickness measurement sustains significantly improved interobserver agreement. Advances in knowledge: Automation of bowel wall thickness measurements strongly increases reproducibility of these measurements, which are commonly used in MRI scoring systems of Crohn's disease activity.

Long-Term Performance of Readers Trained in Grading Crohn Disease Activity Using MRI.

RATIONALE AND OBJECTIVES: We aim to evaluate the long-term performance of readers who had participated in previous magnetic resonance imaging (MRI) reader training in grading Crohn disease activity. MATERIALS AND METHODS: Fourteen readers (8 women; 12 radiologists, 2 residents; mean age 40; range 31-59), who had participated in a previous MRI reader training, participated in a follow-up evaluation after a mean interval of 29 months (range 25-34 months). Follow-up evaluation comprised 25 MRI cases of suspected or known Crohn disease patients with direct feedback; cases were identical to the evaluation set used in the initial reader training (of which readers were unaware). Grading accuracy, overstaging, and understaging were compared between training and follow-up using a consensus score by two experienced abdominal radiologists as the reference standard. RESULTS: In the follow-up evaluation, overall grading accuracy was 73% (95% confidence interval [CI]: 62%-81%), which was comparable to reader training grading accuracy (72%, 95% CI: 61%-80%) (P = .66). Overstaging decreased significantly from 19% (95% CI: 12%-27%) to 13% (95% CI: 8%-21%) between training and follow-up (P = .03), whereas understaging increased significantly from 9% (95% CI: 4%-21%) to 14% (95% CI: 7%-26%) (P < .01). CONCLUSIONS: Readers have consistent long-term accuracy for grading Crohn disease activity after case-based reader training with direct feedback.

Image Registration Based on Autocorrelation of Local Structure.

Registration of images in the presence of intra-image signal fluctuations is a challenging task. The definition of an appropriate objective function measuring the similarity between the images is crucial for accurate registration. This paper introduces an objective function that embeds local phase features derived from the monogenic signal in the modality independent neighborhood descriptor (MIND). The image similarity relies on the autocorrelation of local structure (ALOST) which has two important properties: 1) low sensitivity to space-variant intensity distortions (e.g., differences in contrast enhancement in MRI); 2) high distinctiveness for 'salient' image features such as edges. The ALOST method is quantitatively compared to the MIND approach based on three different datasets: thoracic CT images, synthetic and real abdominal MR images. The proposed method outperformed the NMI and MIND similarity measures on these three datasets. The registration of dynamic contrast enhanced and post-contrast MR images of patients with Crohn's disease led to relative contrast enhancement measures with the highest correlation (r=0.56) to the Crohn's disease endoscopic index of severity.

Expiration-phase template-based motion correction of free-breathing abdominal dynamic contrast enhanced MRI.

This paper studies a novel method to compensate for respiratory and peristaltic motions in abdominal dynamic contrast enhanced magnetic resonance imaging. The method consists of two steps: 1) expiration-phase "template" construction and retrospective gating of the data to the template; and 2) nonrigid registration of the gated volumes. Landmarks annotated by three experts were used to directly assess the registration performance. A tri-exponential function fit to time intensity curves from regions of interest was used to indirectly assess the performance. One of the parameters of the tri-exponential fit was used to quantify the contrast enhancement. Our method achieved a mean target registration error (MTRE) of 2.12, 2.27, and 2.33 mm with respect to annotations by expert, which was close to the average interobserver variability (2.07 mm). A state-of-the-art registration method achieved an MTRE of 2.83-3.10 mm. The correlation coefficient of the contrast enhancement parameter to the Crohn's disease endoscopic index of Severity (r = 0.60, p = 0.004) was higher than the correlation coefficient for the relative contrast enhancement measurements values of two observers ( r(Observer 1) = 0.29, p = 0.2; r(Observer 2) = 0.45, p = 0.04). Direct and indirect assessments show that the expiration-based gating and a nonrigid registration approach effectively corrects for respiratory motion and peristalsis. The method facilitates improved enhancement measurement in the bowel wall in patients with Crohn's disease.

Training readers to improve their accuracy in grading Crohn's disease activity on MRI.

OBJECTIVES: To prospectively evaluate if training with direct feedback improves grading accuracy of inexperienced readers for Crohn's disease activity on magnetic resonance imaging (MRI). METHODS: Thirty-one inexperienced readers assessed 25 cases as a baseline set. Subsequently, all readers received training and assessed 100 cases with direct feedback per case, randomly assigned to four sets of 25 cases. The cases in set 4 were identical to the baseline set. Grading accuracy, understaging, overstaging, mean reading times and confidence scores (scale 0-10) were compared between baseline and set 4, and between the four consecutive sets with feedback. Proportions of grading accuracy, understaging and overstaging per set were compared using logistic regression analyses. Mean reading times and confidence scores were compared by t-tests. RESULTS: Grading accuracy increased from 66 % (95 % CI, 56-74 %) at baseline to 75 % (95 % CI, 66-81 %) in set 4 (P = 0.003). Understaging decreased from 15 % (95 % CI, 9-23 %) to 7 % (95 % CI, 3-14 %) (P < 0.001). Overstaging did not change significantly (20 % vs 19 %). Mean reading time decreased from 6 min 37 s to 4 min 35 s (P < 0.001). Mean confidence increased from 6.90 to 7.65 (P < 0.001). During training, overall grading accuracy, understaging, mean reading times and confidence scores improved gradually. CONCLUSIONS: Inexperienced readers need training with at least 100 cases to achieve the literature reported grading accuracy of 75 %. KEY POINTS: • Most radiologists have limited experience of grading Crohn's disease activity on MRI. • Inexperienced readers need training in the MRI assessment of Crohn's disease. • Grading accuracy, understaging, reading time and confidence scores improved during training. • Radiologists and residents show similar accuracy in grading Crohn's disease. • After 100 cases, grading accuracy can be reached as reported in the literature.

Evaluation of conventional, dynamic contrast enhanced and diffusion weighted MRI for quantitative Crohn's disease assessment with histopathology of surgical specimens.

OBJECTIVES: To prospectively compare conventional MRI sequences, dynamic contrast enhanced (DCE) MRI and diffusion weighted imaging (DWI) with histopathology of surgical specimens in Crohn's disease. METHODS: 3-T MR enterography was performed in consecutive Crohn's disease patients scheduled for surgery within 4 weeks. One to four sections of interest per patient were chosen for analysis. Evaluated parameters included mural thickness, T1 ratio, T2 ratio; on DCE-MRI maximum enhancement (ME), initial slope of increase (ISI), time-to-peak (TTP); and on DWI apparent diffusion coefficient (ADC). These were compared with location-matched histopathological grading of inflammation (AIS) and fibrosis (FS) using Spearman correlation, Kruskal-Wallis and Chi-squared tests. RESULTS: Twenty patients (mean age 38 years, 12 female) were included and 50 sections (35 terminal ileum, 11 ascending colon, 2 transverse colon, 2 descending colon) were matched to AIS and FS. Mural thickness, T1 ratio, T2 ratio, ME and ISI correlated significantly with AIS, with moderate correlation (r = 0.634, 0.392, 0.485, 0.509, 0.525, respectively; all P < 0.05). Mural thickness, T1 ratio, T2 ratio, ME, ISI and ADC correlated significantly with FS (all P < 0.05). CONCLUSIONS: Quantitative parameters from conventional, DCE-MRI and DWI sequences correlate with histopathological scores of surgical specimens. DCE-MRI and DWI parameters provide additional information. KEY POINTS: • Conventional MR enterography can be used to assess Crohn's disease activity. • Several MRI parameters correlate with inflammation and fibrosis scores from histopathology. • Dynamic contrast enhanced imaging and diffusion weighted imaging give additional information. • Quantitative MRI parameters can be used as biomarkers to evaluate Crohn's disease activity.

Grading Crohn disease activity with MRI: interobserver variability of MRI features, MRI scoring of severity, and correlation with Crohn disease endoscopic index of severity.

OBJECTIVE: The purpose of this article is to assess the interobserver variability for scoring MRI features of Crohn disease activity and to correlate two MRI scoring systems to the Crohn disease endoscopic index of severity (CDEIS). MATERIALS AND METHODS: Thirty-three consecutive patients with Crohn disease undergoing 3-T MRI examinations (T1-weighted with IV contrast medium administration and T2-weighted sequences) and ileocolonoscopy within 1 month were independently evaluated by four readers. Seventeen MRI features were recorded in 143 bowel segments and were used to calculate the MR index of activity and the Crohn disease MRI index (CDMI) score. Multirater analysis was performed for all features and scoring systems using intraclass correlation coefficient (icc) and kappa statistic. Scoring systems were compared with ileocolonoscopy with CDEIS using Spearman rank correlation. RESULTS: Thirty patients (median age, 32 years; 21 women and nine men) were included. MRI features showed fair-to-good interobserver variability (intraclass correlation coefficient or kappa varied from 0.30 to 0.69). Wall thickness in millimeters, presence of edema, enhancement pattern, and length of the disease in each segment showed a good interobserver variability between all readers (icc = 0.69, κ = 0.66, κ = 0.62, and κ = 0.62, respectively). The MR index of activity and CDMI scores showed good reproducibility (icc = 0.74 and icc = 0.78, respectively) and moderate CDEIS correlation (r = 0.51 and r = 0.59, respectively). CONCLUSION: The reproducibility of individual MRI features overall is fair to good, with good reproducibility for the most commonly used features. When combined into the MR index of activity and CDMI score, overall reproducibility is good. Both scores show moderate agreement with CDEIS.

Automatic Detection and Segmentation of Crohn's Disease Tissues From Abdominal MRI.

We propose an information processing pipeline for segmenting parts of the bowel in abdominal magnetic resonance images that are affected with Crohn's disease. Given a magnetic resonance imaging test volume, it is first oversegmented into supervoxels and each supervoxel is analyzed to detect presence of Crohn's disease using random forest (RF) classifiers. The supervoxels identified as containing diseased tissues define the volume of interest (VOI). All voxels within the VOI are further investigated to segment the diseased region. Probability maps are generated for each voxel using a second set of RF classifiers which give the probabilities of each voxel being diseased, normal or background. The negative log-likelihood of these maps are used as penalty costs in a graph cut segmentation framework. Low level features like intensity statistics, texture anisotropy and curvature asymmetry, and high level context features are used at different stages. Smoothness constraints are imposed based on semantic information (importance of each feature to the classification task) derived from the second set of learned RF classifiers. Experimental results show that our method achieves high segmentation accuracy with Dice metric values of 0.90 ± 0.04 and Hausdorff distance of 7.3 ± 0.8 mm. Semantic information and context features are an integral part of our method and are robust to different levels of added noise.