Diagnostic performance of image navigated coronary CMR angiography in patients with coronary artery disease

Abstract

Background: The use of coronary MR angiography (CMRA) in patients with coronary artery disease (CAD) remains limited due to the long scan times, unpredictable and often non-diagnostic image quality secondary to respiratory motion artifacts. The purpose of this study was to evaluate CMRA with image-based respiratory navigation (iNAV CMRA) and compare it to gold standard invasive x-ray coronary angiography in patients with CAD.

Methods: Consecutive patients referred for CMR assessment were included to undergo iNAV CMRA on a 1.5 T scanner. Coronary vessel sharpness and a visual score were assigned to the coronary arteries. A diagnostic reading was performed on the iNAV CMRA data, where a lumen narrowing >50% was considered diseased. This was compared to invasive x-ray findings.

Results: Image-navigated CMRA was performed in 31 patients (77% male, 56 ± 14 years). The iNAV CMRA scan time was 7 min:21 s ± 0 min:28 s. Out of a possible 279 coronary segments, 26 segments were excluded from analysis due to stents or diameter less than 1.5 mm, resulting in a total of 253 coronary segments. Diagnostic image quality was obtained for 98% of proximal coronary segments, 94% of middle segments, and 91% of distal coronary segments. The sensitivity and specificity was 86% and 83% per patient, 80% and 92% per vessel and 73% and 95% per segment.

Conclusion: In this study, iNAV CMRA offered a very good diagnostic performance when compared against invasive x-ray angiography. Due to the short and predictable scan time it can add clinical value as a part of a comprehensive CAD assessment protocol.

Keywords: Coronary MR angiography; Coronary artery disease; Image navigators; Respiratory motion correction.

Fig. 1

Reformatted CMRA datasets (top row) from a patient without coronary artery disease but non dominant right coronary artery (RCA). Coronary x-ray angiography in the same patient (bottom row). LAD = left anterior descending artery; LCX = left circumflex artery

Fig. 2

Distribution of visual scores of coronary segments, partitioned into proximal, middle and distal segments. A score of 0 is considered a non-visible coronary segment and 5 a visible segment with sharp edges. Visual scores of 2 or higher are considered to be of diagnostic image quality

Fig. 3

Scatter plots of coronary vessel sharpness versus age, body mass index (BMI), and heart rate. No statistically significant results were found for any of the correlations. NS = not significant

Fig. 4

A receiver operator characteristic curves of iNAV CMRA for detecting significant coronary artery stenosis

Fig. 5

Images from three patients with coronary artery disease, diagnosed using coronary magnetic resonance angiography (top row) and confirmed with coronary x-ray angiography (bottom row)