Abstract:
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Purpose: Phase-contrast Magnetic Resonance (MR) velocity maps can be evaluated by either measuring volume flow or velocity. The workload of both methods differs considerably. The difference in diagnostic accuracies is unknown. The purpose of the present study was to compare volume flow and velocity analyses in MR velocity maps of coronary artery bypass grafts.
Methods and Materials: 49 patients with recurrent chest pain after bypass surgery underwent both coronary angiography and MRI with velocity mapping of the grafts at rest and during adenosine stress. Volume flow (including the whole vessel) and velocity analysis (including 4 pixels) of the MR velocity maps was performed and compared.
Results: 80 single vein grafts in 49 patients were analyzed. The mean duration for performing a volume flow analysis was 25.9 ± 4.3 min, whereas a velocity analysis took 11.1 ± 2.2 min (p<0.05). Bland-Altman analysis showed close agreement between the analysis methods. Comparison of receiveroperating characteristic (ROC) areas under the curve of both analyses revealed no significant difference for detection of a stenosis severity of ³70%. In single vein grafts the sensitivity/specificity/diagnostic accuracy for the volume flow parameters was 91%/92%/92% and for the velocity parameters 95%/92%/93%, respectively.
Conclusion: In the analysis of MR velocity maps in bypass grafts velocity analysis is significantly less time-consuming and has a diagnostic accuracy similar to volume flow analysis. Therefore, velocity analysis appears to be the preferential approach in the analysis of MR velocity maps of vein grafts.
Lamb PhD, H,
Four-Pixel Velocity Analysis is the Preferential Approach in Evaluating Magnetic Resonance Velocity Maps of Coronary Artery Bypass Grafts. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3102806.html
