Carotid Intraplaque Hemorrhage Imaging at 3.0-T MR Imaging: Comparison of the Diagnostic Performance of Three T1-weighted Sequences

Abstract

To compare the diagnostic performances of three T1-weighted 3.0-T magnetic resonance (MR) sequences at carotid intraplaque hemorrhage (IPH) imaging, with histo logic analysis as the reference standard. Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. Twenty patients scheduled for carotid endarterectomy underwent 3.0-T carotid MR imaging, including two-dimensional fast spin-echo, three-dimensional time-of-flight (TOF), and three-dimensional magnetization-prepared rapid acquisition gradient-echo (RAGE) sequences. Two reviewers blinded to the histologic findings assessed the presence, area, and signal intensity of IPH with each sequence. Detection statistics (sensitivity, specificity, and Cohen kappa values) and agreement between area measurements (Pearson correlation coefficient [r] values) were calculated for each sequence. When all 231 available MR sections were included for analysis, the magnetization-prepared RAGE (kappa = 0.53) and fast spin-echo (kappa = 0.42) sequences yielded moderate agreement between MR and histologic measurements, while the TOF sequence yielded fair agreement (k = 0.33). However, when 47 sections with either small IPHs or heavily calcified IPHs were excluded, sensitivity, specificity, and kappa values, respectively, were 80%, 97%, and 0.80 for magnetization-prepared RAGE imaging; 70%, 92%, and 0.63 for fast spin-echo imaging; and 56%, 96%, and 0.57 for TOF imaging. MR imaging-histologic analysis correlation for IPH area was highest with magnetization-prepared RAGE imaging (r = 0.813), followed by TOF (r = 0.745) and fast spin-echo (r = 0.497) imaging. The capability of these three sequences for IPH detection appeared to be in good agreement with the quantitative contrast of IPH versus background plaque tissue. The magnetization-prepared RAGE sequence, as compared with the fast spin-echo and TOF sequences, demonstrated higher diagnostic capability for the detection and quantification of IPH. Potential limitations of 3.0-T IPH MR imaging are related to hemorrhage size and coexisting calcification.