Assessment for Carotid Atherosclerotic Plaque Using Vessel Wall Magnetic Resonance Imaging: A Multireader ROC Study to Determine Optimal Sequence for Detecting Vessel Wall Calcification

Abstract

<b><i>Introduction:</i></b> We aimed to compare conventional vessel wall MR imaging techniques and quantitative susceptibility mapping (QSM) to determine the optimal sequence for detecting carotid artery calcification. <b><i>Methods:</i></b> Twenty-two patients who underwent carotid vessel wall MR imaging and neck CT were enrolled. Four slices of 6-mm sections from the bilateral internal carotid bifurcation were subdivided into 4 segments according to clock position (0–3, 3–6, 6–9, and 9–12) and assessed for calcification. Two blinded radiologists independently reviewed a total of 704 segments and scored the likelihood of calcification using a 5-point scale on spin-echo imaging, FLASH, and QSM. The observer performance for detecting calcification was evaluated by a multireader, multiple-case receiver operating characteristic study. Weighted κ statistics were calculated to assess interobserver agreement. <b><i>Results:</i></b> QSM had a mean area under the receiver operating characteristic curve of 0.85, which was significantly higher than that of any other sequence (<i>p</i> &lt; 0.01) and showed substantial interreader agreement (<i>κ</i> = 0.68). A segment with a score of 3–5 was defined as positive, and a segment with a score of 1–2 was defined as negative; the sensitivity and specificity of QSM were 0.75 and 0.87, respectively. <b><i>Conclusion:</i></b> QSM was the most reliable MR sequence for the detection of plaque calcification.