Renal masses that are interpreted as suspicious on CT may lack MR enhancement because of hemorrhage effects; heterogeneity of their T2 appearance is thus critical in differentiating malignancy from benign disease. Odds-ratio calculations give an adjusted estimate of a 3.36-fold increase (95% confidence interval, 1.8-6.27) in the likelihood of malignancy when masses are heterogeneous on T2-weighted images and a 29-fold increase (95% confidence interval, 3.67-241.8) for predicting malignancy when enhancement is present.

Renal MR contrast enhancement depends on the timing of image acquisition. Limited human trials have demonstrated efficacy of renal artery stents on salvage of renal function. This study assessed the ability of dynamic gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) administration to demonstrate renal artery stenosis and renal stent patency compared to conventional angiography as the gold standard. Twenty subjects referred for renal angiography underwent 22 dynamic MR studies, including 7 with renal artery stenting (Palmaz P204 or P201, Johnson & Johnson, Sydney, Australia). All were examined with conventional angiography and after dynamic Gd-DTPA infusion. Coronal MR images of the kidneys were acquired using a GE Signa 1.5-T magnet (General Electric Medical Systems, Milwaukee, WI) (fast spoiled gradient echo [FSPGR]; TE=4.2 msec, TR=68-150 msec, flip angle=75 degrees) 0 to 600 seconds after iv bolus injection of 15 ml of Gd-DTPA during sequential breath-hold acquisitions, 13 to 32 seconds each. All 51 renal arteries (13 stenosed, 38 normal) were detected with dynamic MRI. Severity of renal artery stenosis was classified correctly with an accuracy of 98% (95% confidence interval [CI]: 85-100), yielding 98% specificity and 100% sensitivity. All nine renal stents were visualized with 100% accurate patency documentation. FSPGR MRI with bolus Gd-DTPA administration can provide adequate time and spatial resolution to demonstrate renal artery stenosis.

Fast spoiled gradient echo magnetic resonance imaging with bolus Gd-DTPA administration can provide adequate time and spatial resolution to demonstrate arterial stent patency.

Magnetic resonance contrast enhancement depends on the relative timing of image acquisition. Limited human trials have demonstrated efficacy of intra-arterial gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) in delineating vascular anatomy with X-rays. The present study assessed the ability of dynamic MR during intra-arterial Gd-DTPA administration to demonstrate vascular anatomy compared to conventional angiography as the gold standard. As interventional MR techniques using dedicated magnets proliferate, the ability to perform invasive MR angiography with a conventional magnet would be of great utility at established sites. Four subjects referred for different types of angiography underwent dynamic MR studies, including one with iliac artery stenting (Palmaz P204, Johnson and Johnson). All were examined with conventional angiography, and again after dynamic intra-arterial (IA) Gd-DTPA infusion. Coronal MRI images of the body were acquired using a 1.5-T superconducting magnet (three with a GE Signa, one with Philips NT), fast spoiled gradient echo (FSPGR); echo time (TE) = 4.2 msec, repetition time (TR) = 68-150 msec, flip = 75 degrees, 0-600 s after dilute Gd-DTPA IA bolus injection during sequential breath-hold acquisitions of 13-32 s each. All arteries were detected with dynamic MR. The FSPGR MRI with IA Gd-DTPA administration can provide adequate time and spatial resolution to demonstrate arterial anatomy and arterial stent patency.