Bone Tissue in Magnetic Resonance Imaging: Contribution of New Zero Echo Time Sequences.

The introduction of new ultrashort and zero echo time (ZTE) sequences is revolutionizing magnetic resonance imaging (MRI) and optimizing patient management. These sequences acquire signals in tissues with very short T2: mineralized bone, cortical bone, and calcium deposits. They can be added to a classic MRI protocol. ZTE MRI provides computed tomography-like contrast for bone.

Pancreatic adenocarcinoma: MRI conspicuity and pathologic correlations.

PURPOSE: To identify the MRI sequences producing the greatest pancreatic adenocarcinoma conspicuity and to assess correlations linking MRI signal intensity and apparent diffusion coefficient to histopathological findings. METHODS: We retrospectively included 22 patients with pancreatic adenocarcinoma who underwent MRI (1.5 or 3 T) before surgical resection. Fat-suppressed (FS) T1- and T2-weighted sequences; 3D FS dynamic T1-weighted gadolinium-enhanced gradient-echo (GRE) imaging at the arterial, portal, and delayed phases; and diffusion-weighted imaging (DWI) with b values of 600-800 s/mm(2) were reviewed. On each sequence, we assessed tumor conspicuity both qualitatively (3-point scale) and quantitatively (tumor-to-proximal and -distal pancreas contrast ratios), and we performed paired Wilcoxon tests to compare these data across sequences. We evaluated correlations between histopathological characteristics and MRI features. RESULTS: 21/22 (95%) tumors were hypointense by 3D FS T1 GRE arterial phase imaging, which produced the greatest tumor conspicuity (p ≤ 0.02). By DWI, 5/20 (25%) of tumors were isointense. The correlation between size by histology and MRI was strongest with DWI. A progressive enhancement pattern was associated with extensive and dense fibrous stroma (p ≤ 0.03). CONCLUSIONS: 3D FS T1 GRE arterial phase imaging produces greater pancreatic adenocarcinoma conspicuity compared to DWI but underestimates tumor size. DWI provides the best size evaluation but fails to delineate the tumor in one-fourth of cases.

Prolonged urinary leakage after partial nephrectomy: a novel management pathway.

INTRODUCTION: To describe an original method for managing prolonged urinary leakage after partial nephrectomy. We placed a Malecot catheter in the ureter to improve the urinary drainage and therefore avoid the renal percutaneous treatment of the fistula or potential open surgery. TECHNICAL CONSIDERATIONS: We performed ureteral stenting using a 16 F Malecot catheter in 3 patients who had a prolonged urinary fistula after partial nephrectomy in which the placement of a ureteral stent could not resolve the urine leak. Drainage using 2 ureteral catheters was performed, which proved to be insufficient for the urinary fistula to resolve. We subsequently placed in the dilated ureter a 16 F Malecot catheter into the renal pelvis using a cystoscopic approach and a bladder catheter to complete the drainage. In all cases, the urine leak stopped after stenting with the Malecot catheter. At 1 month after the stenting, computed tomography and magnetic resonance imaging showed complete healing of the fistula. No infection or secondary ureteral stricture was reported. CONCLUSION: This technique with a low complication profile can be used as an additional endoscopic step, before more invasive procedures.

Malignant rhabdoid tumors of the liver: an exceptional tumor in adults - a case report and literature review.

Malignant rhabdoid tumor (MRT) is a very rare liver tumor, with only a few cases reported in the literature. MRT generally occurs in pediatric patients and prognosis is usually very poor. Here we report a very rare case of MRT occurring in a young adult who is still alive with no sign of recurrence at 41 months of follow-up. MRI and computed tomography scans revealed a voluminous heterogeneous mass in the left liver with no specific pattern. The mass included necrotic and fibrous components. Histology showed fusiform, loosely cohesive cells with abundant eosinophilic cytoplasm resulting in eccentric nuclei, thus creating the characteristic rhabdoid appearance. Immunohistochemical studies revealed a lack of nuclear INI1 protein expression. The patient's treatment included a major left liver resection associated with chemotherapy. A thorough search of the literature revealed one case of MRT in a young adult who died at 48 months of follow-up. A less malignant nature of the tumor in young adults may be suspected, but a longer disease-free survival may also be the fruit of aggressive surgical and oncological treatment.