Assessing carotid plaque neovascularity and calcifications in patients prior to endarterectomy

Abstract

ObjectiveThe objective was to use two ultrasound image and signal processing techniques (MicroPure and superb microvascular imaging [SMI]; Toshiba Medical, Tokyo, Japan) to investigate carotid plaque calcification and intraplaque neovascularity flow as biomarkers for plaque vulnerability in patients before endarterectomy. MethodsThirty patients, with preoperative computed tomography angiography and scheduled for carotid endarterectomy, were enrolled in an institutional review board-approved study. Bilateral grayscale, power Doppler, SMI and MicroPure imaging of the carotids were performed using an Aplio 500 Platinum scanner (Toshiba). MicroPure combines nonlinear imaging and speckle suppression to mark calcifications as white spots in a blue overlay, and SMI uses clutter suppression to extract microvascular flow signals. Readers counted calcifications and scored them as present or absent; intraplaque neovascularity was scored on a 4-point scale by ultrasound imaging as well as by pathology (as the reference). MicroPure and SMI assessments were compared with conventional ultrasound examination and computed tomography angiography with pathology as the reference standard. ResultsOwing to technical difficulties and cancelled operations, 57 carotids were studied; endarterectomies yielded 28 specimens. Intraplaque neovascularization was detected by SMI in significantly more plagues than by power Doppler (41 vs 22 out 57 examined plaques or 72% vs 39%; P < .0001). There was no statistical difference between either reader compared with pathology (P > .37). Sensitivity specificity and accuracy for detecting intraplaque neovascularity based on color SMI and PDI were 84% (95% confidence interval [CI], 64%-96%), 33% (95% CI, 1%-91%), 79% (95% CI, 59%-92%), and 52% (95% CI, 31%-72%), 100% (95% CI, 23%-100%), and 57% (95% CI, 37%-76%), respectively. MicroPure did not correlate with any measures of intraplaque flow (P > .13). ConclusionsSMI may have potential for providing evidence of plaque vulnerability. MicroPure appears less useful in carotid applications.