Measurement of carotid wall volume and maximum area with contrast-enhanced 3D MR imaging: initial observations.

PURPOSE: To investigate whether postcontrast three-dimensional (3D) magnetic resonance (MR) imaging would yield more accurate measurement of carotid artery wall volume and maximum wall area, which are both measures of plaque burden, than precontrast 3D MR imaging.
MATERIALS AND METHODS: Eleven consecutive patients scheduled to undergo carotid endarterectomy were recruited for the study. A 3D fast gradient-recalled-echo sequence was applied to acquire both precontrast and postcontrast images of the carotid artery wall. The same sequence was used to image the ex vivo excised plaque as a reference for measurement of carotid wall volume and maximum wall area.
RESULTS: The mean difference in maximum wall area between the precontrast in vivo measurements and the ex vivo measurements (mean +/- SD, 18.22 mm2 +/- 15.61) was significantly larger than that between the postcontrast in vivo measurements and the ex vivo measurements (12.33 mm2 +/- 14.49) (P =.02). The difference in wall volume between the precontrast in vivo measurements and the ex vivo measurements (41.81 mm3 +/- 36.51) was larger than that between the postcontrast in vivo measurements and the ex vivo measurements (32.73 mm3 +/- 35.00) (P =.004). Postcontrast images yielded better correlation with ex vivo images than did precontrast images, in both carotid luminal area (R = 0.88 for postcontrast images, R = 0.80 for precontrast images) and outer wall boundary area (R = 0.79 for postcontrast images, R = 0.71 for precontrast images) measurements.
CONCLUSION: Postcontrast 3D MR imaging may be useful in the measurement of carotid artery plaque burden.