BackgroundThe 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.MethodsConsecutive 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.ResultsImage-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.ConclusionIn 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.

The coronary arterial system consists of large epicardial coronary arteries, pre-arterioles, and arterioles, which together closely regulate CBF. Structural, functional, and extravascular abnormalities of the microcirculation lead to CMD. CMD can present with symptoms suggestive of CAD, often in the absence of significant obstructive epicardial CAD. Conventional invasive angiography does not allow direct visualization of the microcirculation. Invasive indices, such as CBF and CFR, and non-invasive imaging modalities, such as CMR and PET, can be used to quantify absolute MBF and enable a direct and accurate assessment of coronary microvascular function. CMD appears to be more prevalent in women, typically presenting with symptoms of ischemia with unobstructed coronary arteries, and has a relatively unfavorable prognosis. CMD is classified clinically depending on the presence or absence of epicardial CAD, myocardial disease, or iatrogenic causes. Although invasive intracoronary techniques can be used to detect CMD, these cannot provide insight into the mechanisms involved in its pathogenesis. Imaging modalities such as CMR and cardiac PET are becoming indispensable tools in the evaluation of suspected CMD.

Echocardiography-derived measurements of maximum left ventricular (LV) wall thickness are important for both the diagnosis and risk stratification of hypertrophic cardiomyopathy (HC). Cardiac magnetic resonance (CMR) imaging is increasingly being used in the assessment of HC; however, little is known about the relation between wall thickness measurements made by the 2 modalities. We sought to compare measurements made with echocardiography and CMR and to assess the impact of any differences on risk stratification using the current European Society of Cardiology guidelines. Maximum LV wall thickness measurements were recorded on 50 consecutive patients with HC. Sixty-nine percent of LV wall thickness measurements were recorded with echocardiography, compared with 69% from CMR (p <0.001). There was poor agreement on the location of maximum LV wall thickness; weighted-Cohen's κ 0.14 (p = 0.036) and maximum LV wall thicknesses were systematically higher with echocardiography than with CMR (mean 19.1 ± 0.4 mm vs 16.5 ± 0.3 mm, p <0.01, respectively); Bland-Altman bias 2.6 mm (95% confidence interval -9.8 to 4.6). Interobserver variability was lower for CMR (R 0.67 echocardiography, R 0.93 CMR). The mean difference in 5-year sudden cardiac death (SCD) risk between echocardiography and CMR was 0.49 ± 0.45% (p = 0.37). When classifying patients (low, intermediate, or high risk), 6 patients were reclassified when CMR was used instead of echocardiography to assess maximum LV wall thickness. These findings suggest that CMR measurements of maximum LV wall thickness can be cautiously used in the current European Society of Cardiology risk score calculations, although further long-term studies are needed to confirm this.

Aims Developments in myocardial perfusion cardiovascular magnetic resonance (CMR) allow improvements in spatial resolution and/or myocardial coverage. Whole heart coverage may provide the most accurate assessment of myocardial ischaemic burden, while high spatial resolution is expected to improve detection of subendocardial ischaemia. The objective of this study was to compare myocardial ischaemic burden as depicted by 2D high resolution and 3D whole heart stress myocardial perfusion in patients with coronary artery disease. Methods and results Thirty-eight patients [age 61 ± 8 (21% female)] underwent 2D high resolution (spatial resolution 1.2 mm2) and 3D whole heart (in-plane spatial resolution 2.3 mm2) stress CMR at 3-T in randomized order. Myocardial ischaemic burden (%) was visually quantified as perfusion defect at peak stress perfusion subtracted from subendocardial myocardial scar and expressed as a percentage of the myocardium. Median myocardial ischaemic burden was significantly higher with 2D high resolution compared with 3D whole heart [16.1 (2.0–30.6) vs. 13.4 (5.2–23.2), P = 0.004]. There was excellent agreement between myocardial ischaemic burden (intraclass correlation coefficient 0.81; P &lt; 0.0001), with mean ratio difference between 2D high resolution vs. 3D whole heart 1.28 ± 0.67 (95% limits of agreement −0.03 to 2.59). When using a 10% threshold for a dichotomous result for presence or absence of significant ischaemia, there was moderate agreement between the methods (κ = 0.58, P &lt; 0.0001). Conclusion 2D high resolution and 3D whole heart myocardial perfusion stress CMR are comparable for detection of ischaemia. 2D high resolution gives higher values for myocardial ischaemic burden compared with 3D whole heart, suggesting that 2D high resolution is more sensitive for detection of ischaemia.