This preliminary experience in rats shows that dynamic diffusion-weighted MRI can be used to study noninvasively the in vivo renal hemodynamic response after injection of iodinated contrast.

MR venography is an accurate, noninvasive technique that is as useful as conventional venography for the planning of hemodialysis access fistula creation.

The aim of this study was to evaluate the usefulness of gadolinium-enhanced time-of-flight magnetic resonance venography (MRV) in the diagnosis of bland thrombosis/tumoral invasion in the preoperative assessment of renal cell carcinoma. Preoperative precontrast and enhanced GRE fast lowangle shot (FLASH) images of 36 patients with renal adenocarcinoma were reviewed and compared with pre- and post-contrast T1-weighted images. All patients underwent surgery, and MR findings were blindly and prospectively compared with surgical and pathologic data, considered the standard. Renal vein and vena cava were involved in 17 and 9 patients, respectively; right atrial extension was present in one patient. Precontrast spin-echo (SE) and FLASH images were 88% sensitive and 100% specific in the detection of venous involvement, respectively, and enhanced FLASH images 100% sensitive and 96% specific. The nature of thrombus (neoplastic or bland) was more accurately assessed (McNemar's, p < 0.05) with FLASH-enhanced MR images (sensitivity 89%; specificity 96%) than with SE and precontrast FLASH images (sensitivity 79%; specificity 94%). Our data suggest that use of Gd-enhanced MRV might improve preoperative assessment of vascular involvement in renal carcinoma.

The purpose of this study was to assess the diagnostic value of two-dimensional (2D) MR subtraction angiography of lower extremities in patients with symptomatic peripheral arterial occlusive disease with conventional angiography as the standard of reference. Twenty patients were prospectively included. 2D subtraction MR angiography (MRA) consisted of multisection gradient-recalled echo (GRE) acquisitions with the shortest TE available on our machine (4 msec), obtained in the coronal plane before and after intravenous bolus administration of gadolinium chelate. MR images were reconstructed after subtraction with a maximum-pixel-intensity-projection (MIP) algorithm. MRA was performed in all cases 1-4 days before diagnostic angiography. In a prospective blinded analysis, the number and location of significant (ie, >50%) stenoses and occlusions were evaluated for each vascular segment. Sensitivity and specificity were used to evaluate MRA data. Significant stenoses (38 of 46, 83%) and occlusions (66 of 67, 99%) seen at conventional angiography were identified with MRA. The sensitivity and specificity of MRA for determination of stenoses >50% or occlusions was 100% and 97%, respectively. The location and extent of stenoses and/or occlusions on MRA and angiograms were well correlated (kappa values, r = .73, P < .05). Contrast 2D MR subtraction angiography, by providing comparable information to that of conventional angiography, is well suited to evaluate the presence and severity of atherosclerotic lesions of the lower limbs.

No abstract