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Idiopathic segmental infarction of the greater omentum is a rare disorder presenting with nonspecific clinical symptoms that may mimic a variety of acute abdominal conditions. We describe the diagnosis and treatment of two patients who had idiopathic infarction of the greater omentum and presented with localized abdominal pain, mimicking acute cholecystitis and acute diverticulitis, respectively. Patients underwent unenhanced multidetector-row computed tomography (CT) examination, which demonstrated the characteristic features of omental infarction, consisting of a heterogeneous density fatty mass, containing hyperattenuating streaks, located in the greater omentum, between the anterior abdominal wall and the colon; a moderate amount of free peritoneal fluid was also present. There were no other pathological abdominal findings. Giving persisting and worsening symptoms, both patients underwent laparoscopy with resection of the necrotic portion of the omentum. Pathology confirmed the preoperative diagnosis. Unenhanced CT allows us to obtain a reliable diagnosis of omental infarction in patients with acute abdominal pain and may help in selecting the appropriate medical or surgical therapy.

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Objectives (1) To investigate whether a contrast-free biparametric MRI (bp-MRI) including T2-weighted images (T2W) and diffusion-weighted images (DWI) can be considered an accurate alternative to the standard multiparametric MRI (mp-MRI), consisting of T2, DWI, and dynamic contrast-enhanced (DCE) imaging for the muscle-invasiveness assessment of bladder cancer (BC), and (2) to evaluate how the diagnostic performance of differently experienced readers is affected according to the type of MRI protocol. Methods Thirty-eight patients who underwent a clinically indicated bladder mp-MRI on a 3-T scanner were prospectively enrolled. Trans-urethral resection of bladder was the gold standard. Two sets of images, set 1 (bp-MRI) and set 2 (mp-MRI), were independently reviewed by four readers. Descriptive statistics, including sensitivity and specificity, were calculated for each reader. Receiver operating characteristic (ROC) analysis was performed, and the areas under the curve (AUCs) were calculated for the bp-MRI and the standard mp-MRI. Pairwise comparison of the ROC curves was performed. Results The AUCs for bp- and mp-MRI were respectively 0.91–0.92 (reader 1), 0.90 (reader 2), 0.95–0.90 (reader 3), and 0.90–0.87 (reader 4). Sensitivity was 100% for both protocols and specificity ranged between 79.31 and 89.66% and between 79.31 and 83.33% for bp-MRI and mp-MRI, respectively. No significant differences were shown between the two MRI protocols (p > 0.05). No significant differences were shown accordingly to the reader’s experience (p > 0.05). Conclusions A bp-MRI protocol consisting of T2W and DWI has comparable diagnostic accuracy to the standard mp-MRI protocol for the detection of muscle-invasive bladder cancer. The experience of the reader does not significantly affect the diagnostic performance using VI-RADS. Key Points • The contrast-free MRI protocol shows a comparable accuracy to the standard multiparametric MRI protocol in the bladder cancer muscle-invasiveness assessment. • VI-RADS classification helps non-expert radiologists to assess the muscle-invasiveness of bladder cancer. • DCE should be carefully interpreted by less experienced readers due to inflammatory changes representing a potential pitfall.

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