Low-dose 3D time-resolved magnetic resonance angiography (MRA) of the supraaortic arteries: correlation with high spatial resolution 3D contrast-enhanced MRA

Purpose

To evaluate the feasibility of low‐dose, 3D time‐resolved contrast‐enhanced magnetic resonance angiography (TR‐CEMRA) in the assessment of the supraaortic vessel, and to compare the results with high‐resolution contrast‐enhanced MRA (HR‐CEMRA).

Materials and Methods

This was an Institutional Review Board‐approved retrospective study. Forty‐five consecutive patients underwent contrast‐enhanced 3D TR‐CEMRA and 3D HR‐CEMRA for evaluation of neurovascular disease at 3.0 T. Gadobutrol was administered at a constant dose of 1 mL for TR‐CEMRA (independent of patient weight), and 0.1 mmol/kg for HR‐CEMRA. Two readers evaluated image quality using a four‐point scale (from 0 = excellent to 3 = nondiagnostic), and subsequently graded each stenosis into clinically relevant categories: normal (0%), mild stenosis (<50%), moderate to severe (>50%), and occlusion.

Results

The overall image quality for low‐dose TR‐CEMRA was in the diagnostic range (median 0, range 0–3). On the grading of stenosis, TR‐CEMRA using the TWIST sequence correlated with HR‐CEMRA (r = 0.668, P < 0.001). In terms of the comparison of TR‐CEMRA with HR‐CEMRA, of the 675 supraaortic arterial segments evaluated for stenosis or occlusion, agreement occurred in 611 of 675 (90.5%), overestimation in 41 of 675 (6.1%), and underestimation 23 of 675 (3.4%).

Conclusion

TR‐CEMRA achieved by administration of a small contrast dose (1 cc) yields rapid and important functional and anatomical information in the evaluation of supraaortic arteries. Due to limited spatial resolution, TR‐CEMRA at the current parameters has a tendency to overestimate the stenosis of smaller intracranial arteries compared to HR‐CEMRA. J. Magn. Reson. Imaging 2011;33:71–76. © 2010 Wiley‐Liss, Inc.