Peripheral arterial occlusive disease: evaluation of a high spatial and temporal resolution 3-T MR protocol with a low total dose of gadolinium versus conventional angiography

Abstract

Purpose: To evaluate a peripheral magnetic resonance (MR) angiographic protocol combining continuous table movement (CTM) MR angiography of the entire runoff vasculature with time-resolved (TWIST) 3-T MR angiography of the calves with a total gadolinium dose of 0.1 mmol per kilogram of body weight.

Materials and methods: In this retrospective institutional review board-approved study, 31 consecutive patients (22 men, nine women; mean age, 65 years ± 14 [standard deviation]) with peripheral arterial occlusive disease who had undergone a low-dose MR angiographic protocol that consisted of CTM MR angiography (repetition time msec/echo time msec, 2.4/1.0; 21° flip angle; voxel size, 1.2 mm(3); gadolinium dose, 0.07 mmol per kilogram of body weight) and TWIST MR angiography (2.8/1.1; 20° flip angle; voxel size, 1.1 mm(3); temporal resolution, 4.8-5.5 sec, gadolinium dose, 0.03 mmol/kg), as well as digital subtraction angiography (DSA), were included. Two radiologists rated image quality and stenosis degree on four-point scales. The accuracy of stenosis gradation and, specifically, the detection of high-grade stenoses (stenosis of 70%-99%) with CTM MR angiography alone and with the combined protocol were compared with accuracy of stenosis gradation and detection of high-grade stenoses with DSA. Means and standard deviations were calculated for all data. Interobserver agreement was determined with κ statistics. Positive and negative predictive values, sensitivity, specificity, and overall diagnostic accuracy were calculated for CTM MR angiography alone and for the combined protocol.

Results: For CTM MR angiography, image quality was good or excellent in 95.9% of vessel segments; for TWIST MR angiography, image quality was good or excellent in 94.3% and 97.8% of vessel segments for readers 1 and 2, respectively. The combined protocol resulted in high overall diagnostic accuracy of more than 80% for detection of stenosis and diagnostic accuracy of 93.5% for detection of high-grade vessel stenosis. Inclusion of TWIST MR angiography increased diagnostic value over that achieved with CTM MR angiography alone.

Conclusion: A combined MR angiographic approach in which a low total gadolinium dose (0.1 mmol/kg) is used yields excellent image quality and is accurate in the diagnosis of peripheral arterial stenosis.