What’s New in Gastrointestinal Imaging? – September 2022

2 years ago

Interobserver variation in the interpretation of magnetic resonance enterography in Crohn’s disease – British Journal of Radiology


Magnetic resonance enterography (MRE) is highly accurate for diagnosing the presence and activity/severity of Crohn’s disease. Many of the imaging findings in Crohn’s disease, particularly early on, may be subtle, which leads to interobserver variation in image interpretation. This study aims to investigate interobserver variation regarding overall disease presence and activity. Twenty radiologists participated in interpreting MRE datasets of 73 patients with Crohn’s disease. Each data set was read by three different radiologists, who determined segmental disease presence, activity, and extra-enteric manifestations based on their normal reporting practices. These radiologists also documented their diagnostic certainty of disease presence/activity in each bowel segment on a scale of 1 (least certain) to 6 (most certain). For evaluation of disease presence, agreement was 68% for newly diagnosed CD and 78% for relapsed CD.  Agreement for disease extent was 43% in newly diagnosed CD and 53% for relapsed CD. Interobserver agreement was greater with more advanced disease. The findings in this study suggest that there is a reasonable amount of agreement between radiologists regarding the presence of CD on MRE, while there is less agreement as to the extent of disease.

Bhatnagar G, Mallett S, Quinn L, Beable R, Bungay H, Betts M, Greenhalgh R, Gupta A, Higginson A, Hyland R, Ilangovan R, Lambie H, Mainta E, Patel U, Pilcher J, Plumb A, Porté F, Sidhu H, Slater A, Tolan D, Zealley I, Halligan S, Taylor S, and . Interobserver variation in the interpretation of magnetic resonance enterography in Crohn’s disease. Br J Radiol 2022; 95: 20210995.

Velocity-Encoded Phase-Contrast MRI for Measuring Mesenteric Blood Flow in Patients With Newly Diagnosed Small-Bowel Crohn Disease – American Journal of Radiology


Diagnosis, assessment of treatment response and detection of complications of Crohn’s Disease (CD) has typically relied on imaging findings (through magnetic resonance and computed tomography enterography) including bowel wall thickening, abnormal intramural signal, peri enteric inflammation, mucosal ulcerations and hyperenhancement after IV contrast administration. Crohn’s disease leads to an abnormal increase in mesenteric blood flow, which indirectly manifests as engorged mesenteric vasa recta and bowel wall hyperenhancement. As no imaging based quantitative measures of mesenteric blood flow are routinely used in clinical practice, this study evaluates the use of velocity-encoded phase-contrast MRI to measure mesenteric blood flow in patients with newly diagnosed CD. 17 patients with newly diagnosed CD underwent 3 MRI examinations over a period of 6 months (one at baseline, one at 6 weeks, and one at 6 months after diagnosis), which included the velocity encoded phase-contrast dataset. Quantitative blood flow measurements of the SMA, SMV and aorta were evaluated to assess the degree of ileal inflammation using a standardized scaled score. Mesenteric blood flow was found to be quantifiable using these MRI acquisition methods. These flow velocities were also found to differ significantly between patients with ileal CD and healthy patients. Dynamic flow changes were noted in patients with ileal CD in response to medical therapy. Although this study was small in sample size, it demonstrates that velocity-encoded phase-contrast MR may have a future role in diagnosis and treatment monitoring for CD.

Ata, N. A., Dillman, J. R., Gandhi, D., Dudley, J. A., Trout, A. T., Imbus, R., Towbin, A. J., Denson, L. A., & Tkach, J. A. (2022). Velocity-encoded phase-contrast MRI for measuring mesenteric blood flow in patients with newly diagnosed small-bowel crohn disease. American Journal of Roentgenology, 219(1), 132–141.

Diagnostic performance of triple-contrast versus single-contrast multi-detector computed tomography for the evaluation of penetrating bowel injury – Emergency Radiology


Some patients with low risk penetrating abdominal trauma may undergo “selective nonoperative management” (SNOM) in which they forgo surgery/laparotomy. The selection process for SNOM may be challenging. Most trauma centers use IV contrast-enhanced CT to evaluate penetrating abdominal trauma, however, bowel injury remains a major missed diagnosis with associated morbidity and mortality. The use of triple contrast CT (oral, rectal and IV contrast at once) has shown accuracy in predicting surgically important penetrating trauma injuries, but has been met with skepticism among surgeons and radiologists. This retrospective study aims to compare the diagnostic performance of single vs triple contrast CT for detection of penetrating abdominal injury.  143 patients with penetrating trauma who received a CT prior to laparotomy were included in the study. 45 patients were found to have bowel injury (35 received single contrast CT, 10 received triple contrast CT). 98 patients had no bowel injury at laparotomy, divided roughly 50% between single and triple contrast CT. The CT examinations were reviewed by radiologists and graded based on the probability of hollow vicus injury. The authors found that specificity and accuracy were higher with triple contrast vs single contrast, although their results were not statistically significant. This study suggests that triple contrast CT may be useful in the future triage of penetrating trauma, although, as noted by the authors, further studies are needed for confirmation.

Paes, F.M., Durso, A.M., Pinto, D.S. et al. Diagnostic performance of triple-contrast versus single-contrast multi-detector computed tomography for the evaluation of penetrating bowel injury. Emerg Radiol 29, 519–529 (2022).

Diagnostic accuracy of ultrasound in diagnosing acute appendicitis in pregnancy: a systematic review and meta-analysis – Emergency Radiology

Acute appendicitis (AA) is one of the most common causes of emergency surgery in pregnancy and can lead to maternal and fetal complications if there is a delayed or missed diagnosis. AA may be underdiagnosed in 25-50% of cases. Additionally, up to 23% of pregnant patients who undergo emergency surgery have no appendicitis. Thus, imaging methods that can lead to timely and accurate diagnosis of AA is important. This meta-analysis included 8 studies which encompassed a combined total 1593 pregnant women with suspected appendicitis. Among the studies included, the prevalence of AA was 54.7% in pregnant patients suspected to have AA. The rate of perforation, a common complication of AA was found to increase with trimester, which indicates increasing difficulty diagnosing AA later in pregnancy. Patients with suspected AA and subsequent negative laparotomy was between 25-50% in pregnant patients, while in nonpregnant women the rate was 15-35%. This meta-analysis also found a low diagnostic performance of US in determining AA in pregnant women, with a sensitivity of 77% and specificity of 75%. The authors concluded that US has a low accuracy for AA in pregnant women and that alternative imaging should still be considered after negative or equivocal US.

Moghadam, M.N., Salarzaei, M. & Shahraki, Z. Diagnostic accuracy of ultrasound in diagnosing acute appendicitis in pregnancy: a systematic review and meta-analysis. Emerg Radiol 29, 437–448 (2022).

Computed tomographic enterography (CTE) in evaluating bowel involvement in patients with ovarian cancer – Abdominal Radiology


Surgical resection plays a crucial role in the treatment of ovarian cancer. Both the surgical technique and patient morbidity/mortality are influenced by bowel involvement in ovarian cancer. Prior studies have found that neither abdominal/pelvic CT nor MR are reliable for presurgical planning. This study aims to evaluate the diagnostic utility of computed tomography enterography (CTE) in identifying depth of bowel invasion in ovarian cancer for the purposes of presurgical planning. Clinical and imaging data of 73 patients with histologically proven ovarian, tubal or peritoneal cancer were analyzed. These patients had undergone an oral contrast protocol prior to undergoing pre-operative CTE examination. These CTE datasets were then interpreted by two experienced radiologists, who were blinded to surgical and pathology results. The sensitivity and specificity in identifying small bowel invasion were 87.5% and 92.31%, respectively, while the positive/negative predictive values and accuracy were 58.33%, 98.36%, and 91.78%. For large bowel involvement the sensitivity, specificity, PPV, NPV, and accuracy were 58.82%, 96.43%, 83.33%, 88.52%, and 87.67%, respectively. Sigmoid/rectal involvement was not able to be reliably detected with CTE. The authors found that CTE had high sensitivity and specificity for pre-surgical diagnosis of small bowel invasion and high specificity for large bowel invasion due to ovarian, tubal, and peritoneal cancers and thus may be a good option for pre-surgical planning.

Zhang, XM., Zhang, XY., Liu, YX. et al. Computed tomographic enterography (CTE) in evaluating bowel involvement in patients with ovarian cancer. Abdom Radiol 47, 2023–2035 (2022).



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