title: On contrast-enhanced magnetic resonance angiography of the aortoiliac arteries.
abstract: In contrast-enhanced MR angiography (CE-MRA), vascular signal is produced by the acquisition of a T1-weighted MR imaging scan while the presence of a contrast agent induces a low T1 in blood. In this thesis, CE-MRA of the aortoiliac arteries was evaluated. Different contrast agents and techniques for synchronisation of the scan with the contrast bolus passage were assessed. In 30 patients with clinically suspected iliac artery stenoses, CE-MRA was compared with duplex ultrasound scanning (DUS) and digital subtraction X-ray angiography (DSA), with intra-arterial pressure measurements as reference. No statistically significant differences in sensitivity or specificity were observed between the techniques regarding detection of haemodynamically significant iliac stenoses. The use of multiplanar reformat and source images in the MRA examinations was of value for differentiation between highgrade stenoses and occlusions. With DSA as reference method, MRA had significantly higher sensitivity and specificity than DUS for detection of > or = 50% stenoses. In 14 patients who underwent iliac artery MRA, differences in contrast arrival time of up to 7 s were observed between the aorta and the common femoral artery. A dual-station timing technique adjusting for this difference was found feasible. Compared with a fluoroscopically triggered technique (n = 13), which is used in clinical routine, the dual-station technique was more reliable for the visualisation of distal vessels. In a clinical phase II study comparing doses of the contrast agent gadobenate dimeglumine from 0.0125 to 0.2 mmol/kg b.w. for enhancement of iliac artery MRA, significant improvement in subjective diagnostic quality compared with time-of-flight-MRA was found at all doses from 0.025 mmol/kg b.w. An increasing trend with dose was observed up to a dose of 0.05-0.1 mmol/kg b.w. In a phase I clinical study on the intravascular iron oxide contrast agent NC100150 Injection, a positive dose response was observed for abdominal vascular enhancement, with the highest contrast-to-noise ratio observed at 4.0 mg Fe/kg b.w. at 1.5 T and at 2.5-4 mg Fe/kg b.w. at 0.5 T. At 1.5 T higher calculated R2* values were found for the aorta than for the inferior vena cava.
authors.affiliation: Department of Oncology, Radiology and Clinical Immunology, Section of Radiology, Uppsala University Hospital, SE-751 85 Uppsala, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Wikström
mesh_terms: D004212:Academic Dissertations as Topic; D015901:Angiography, Digital Subtraction; D001011:Aorta / Q000000981:diagnostic imaging / Q000473:pathology*; D001027:Aortography; D001161:Arteriosclerosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007083:Iliac Artery / Q000000981:diagnostic imaging* / Q000473:pathology*; D018810:Magnetic Resonance Angiography; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018616:Ultrasonography, Doppler, Duplex
chemical_list: D003287:Contrast Media