Dynamic contrast material-enhanced gradient-echo magnetic resonance (MR) imaging was performed on 15 patients with 18 renal masses (seven simple renal cysts, nine renal cell carcinomas, one angiomyolipoma, and one oncocytoma). Fifteen sequential images were obtained while the patients held their breath during a 2.5-3.5-minute interval during and immediately after the intravenous administration of gadolinium diethylenetriaminepentaacetic acid (DTPA); delayed images were also obtained for 15 minutes. Time-intensity curves showed that renal cortical enhancement reached maximal intensity 80 seconds after the injection of Gd-DTPA. Medullary enhancement reached maximal intensity at 120 seconds. None of the simple renal cysts showed enhancement; each cyst displayed a signal intensity less than that of the renal cortex on precontrast images. All renal cell carcinomas were isointense with the renal cortex and demonstrated variable enhancement. Three patterns of enhancement were observed: predominantly peripheral, heterogeneous, and homogeneous. Both the angiomyolipoma and the oncocytoma showed brisk, homogeneous enhancement. This MR imaging technique appears to be useful in the detection and characterization of simple renal cysts and solid neoplasms.

The utility of perfluoroctylbromide (PFOB) as a gastrointestinal contrast agent for magnetic resonance (MR) imaging was evaluated with MR examinations performed in 30 subjects (16 healthy volunteers and 14 patients). Transaxial T1-, proton density-, and T2-weighted MR images were acquired in each subject before and after the administration of PFOB. The healthy volunteers each underwent two sets of post-PFOB MR examinations, one before and one after glucagon administration. The degree of bowel marking, clarity of bowel-wall visualization, ability to distinguish bowel from adjacent parenchymal organs, and severity of phase-encoding artifacts were independently analyzed by two reviewers. Oral administration of PFOB significantly (P less than .001) increased the percentage of bowel loops with low signal intensity. Subcutaneous administration of glucagon significantly (P less than .001) increased the clarity of bowel-wall visualization on post-PFOB MR studies. The severity of phase-encoding artifacts did not change substantially after administration of PFOB or glucagon.

No abstract

Rapid acquisition spin-echo (RASE) magnetic resonance (MR) imaging allows for coverage of the entire liver with highly T1-weighted SE images during a single 23-second breath-holding period. The RASE sequence was implemented in conjunction with rapid intravenous injection of gadopentetate dimeglumine to enable performance of dynamic contrast material-enhanced MR imaging of the liver. Prospective evaluation of 24 patients with 62 liver lesions 1 cm or greater in diameter was performed. Images obtained with RASE were devoid of respiratory-related ghost artifacts or edge blurring. The dynamic contrast-enhanced RASE technique resulted in contrast-to-noise and contrast-to-artifact values and time efficiency measures significantly greater (P less than .05) than those obtained with use of conventional T1- and T2-weighted pulse sequences, indicating a higher likelihood for lesion detectability. Lesion conspicuity was maximal during or immediately following bolus administration of gadopentetate dimeglumine, with lesions often becoming obscured at delayed postcontrast imaging.

No abstract