MR differentiation of phaeochromocytoma from other adrenal lesions based on qualitative analysis of T2 relaxation times.

AIM: To determine the diagnostic accuracy of MR imaging in differentiating phaeochromocytoma from other adrenal lesions. MATERIALS AND METHODS: Sixty-seven adrenal masses (65 patients) including 17 phaeochromocytomas were imaged using T2-weighted pulse sequences on 0.6 T and 1.5 T GE MR units. The adrenal lesions were qualitatively assessed by three observers and divided into three categories (benign adenomas, malignant lesions and phaeochromocytomas) based on lesion signal intensity relative to liver and cerebrospinal fluid. RESULTS: Eleven phaeochromocytomas (65%) were correctly identified while the remaining six (35%) were misclassified, five as malignant lesions and one as a benign adenoma, because of atypical low signal intensity on T2-weighted MR images. Conversely, six non-phaeochromocytomas (three benign adenomas, two adrenal carcinomas and one metastasis) were wrongly classified as phaeochromocytomas because of very high lesion signal intensity. The sensitivity of MR imaging for diagnosing phaeochromocytoma was 64.7%, specificity 88.0%, positive predictive value 64.7% and negative predictive value 88.0%. CONCLUSION: There is considerable overlap between the MR appearance of phaeochromocytoma and other adrenal lesions. A phaeochromocytoma cannot be excluded on the basis of a lack of high signal intensity on T2-weighted MR imaging.

Antibiotic-induced diarrhea: specificity of abdominal CT for the diagnosis of Clostridium difficile disease.

PURPOSE: To evaluate the specificity of abdominal computed tomography (CT) in the diagnosis of Clostridium difficile disease. MATERIALS AND METHODS: The authors retrospectively reviewed CT scans of 64 patients with C difficile disease and 30 control subjects with diarrhea and negative findings for C difficile disease at stool tests. RESULTS: Colon wall thickening (range, 4-22 mm; mean, 11.7 mm; median, 11 mm) was seen in 39 patients (61%) with C difficile disease. Other findings included focal colon wall thickening (n = 28) and pancolonic thickening (n = 11). Two patients had only right-sided and transverse colon involvement. CT-specific diagnostic features of C difficile disease, such as nodular haustral thickening or the accordion pattern, were present in 17% of patients. No colonic abnormality was detected in 25 patients (39%). Seven of the 30 (23%) control subjects had colon wall thickening. Six of those seven subjects were subsequently determined to have ischemic colitis. The sensitivity of CT in the detection of colon abnormalities in patients with C difficile disease was 85%, and the specificity was 48%. CONCLUSION: Specific CT features of C difficile disease are uncommon. A considerable number of patients (39%) with C difficile disease have normal abdominal CT scans.