The data indicate that sufficient contrast consumption and optimal timing of data acquisition are essential to distention of the small bowel. Oral contrast agent protocols should be adapted to the bowel region in question.
Whole-body MR angiography permits a rapid, noninvasive, and accurate evaluation of the lower peripheral arterial system in patients with peripheral arterial occlusive disease, and it may allow identification of additional relevant vascular disease that was previously undetected.
Institutional review board approval and patient written informed consent were obtained. On two separate occasions, 24 hours apart, contrast-enhanced cardiac magnetic resonance (MR) imaging was performed prospectively at 1, 3, 5, 10, and 20 minutes after injection of gadopentetate dimeglumine and gadobenate dimeglumine in 15 patients (11 men, four women) with history of myocardial infarction. Both agents allowed detection of infarcted myocardium. T1 values at all times were significantly (P < .05) lower for gadobenate, compared with values for gadopentetate, in both infarcted and noninfarcted myocardium. At 1 minute after administration of both agents, T1 values in left ventricular cavity (LVC) were not different; at 3-20 minutes after injection, values were significantly (P < .05) lower for gadobenate. Differences between contrast-to-noise ratio (CNR) values of infarcted and noninfarcted myocardium were significantly higher on gadobenate-enhanced images (P < .05). CNR values between infarcted myocardium and LVC were significantly higher on gadopentetate-enhanced images (P < .05). Gadopentetate might permit better delineation of infarcts, especially subendocardial infarcts.
Five volunteers and 10 patients suspected of having peripheral vascular disease underwent multistation contrast material-enhanced three-dimensional whole-body magnetic resonance (MR) angiography. The first examination, based on standard protocol, lasted 72 seconds, while the following two examinations, performed with a high-spatial-resolution T1-weighted gradient-recalled-echo sequence for the last two stations (lower extremities) lasted 170 seconds. In the second high-resolution examination, midfemoral venous compression was used. Intraindividual comparison showed the high-resolution protocol with venous compression resulted in the best qualitative and quantitative image quality through higher signal-to-noise and contrast-to-noise ratios in the calf arteries. Despite prolonged acquisition times, there was no venous contamination. The data suggest that midfemoral venous compression should be incorporated in multistation protocols of the lower extremities to improve depiction of calf arteries without disturbing venous overlap.
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