Application of mask images of contrast-enhanced MR angiography to detect carotid intraplaque hemorrhage in patients with moderate to severe symptomatic and asymptomatic carotid stenosis

Purpose: Carotid intraplaque hemorrhage (IPH) on MRI predicts stroke. Magnetization-prepared rapid acquisition gradient (MP-RAGE) is widely used to detect IPH. CE-MRA is used routinely to assess stenosis. Initial studies indicated that IPH can be identified on mask images of CE-MRA, while Time-of-Flight (TOF) images were reported to have high specificity but lower sensitivity. We investigated the diagnostic accuracy of detecting IPH on mask images of CE-MRA and TOF.Methods: Thirty-six patients with >= 50% stenosis enrolled in the ongoing 2nd European Carotid Surgery Trial underwent carotid MRI. A 5-point quality score was used. Inter-observer agreement between two independent readers was determined. The sensitivity and specificity of IPH detection on mask MRA and TOF were calculated with MP-RAGE as a reference standard.Results: Of the 36 patients included in the current analysis, 66/72 carotid arteries could be scored. The inter observer agreements for identifying IPH on MP-RAGE, mask, and TOF were outstanding (kappa: 0.93, 0.96, and 0.85). The image quality of mask (1.42 +/- 0.66) and TOF (2.42 +/- 0.66) was significantly lower than MP-RAGE (3.47 +/- 0.61). When T1w images were used to delineate the outer carotid wall, very high specificities (>95%) of IPH detection on mask and TOF images were found, while the sensitivity was high for mask images (>81%) and poor for TOF (50-60%). Without these images, the specificity was still high (>97%), while the sensitivity reduced to 62-71%.Conclusion: Despite the lower image quality, routinely acquired mask images from CE-MRA, but not TOF, can be used as an alternative to MP-RAGE images to visualize IPH.

Automated summary

This study investigated the diagnostic accuracy of detecting intraplaque hemorrhage (IPH) by using mask images from CE-MRA and TOF. The mask images from CE-MRA showed high specificity, while the TOF images had lower sensitivity.