Hypertrophic cardiomyopathy in cardiac CT: a validation study on the detection of intramyocardial fibrosis in consecutive patients

Hypertrophic Cardiomyopathy (HCM) confers a 4–5 %/year-risk for sudden cardiac death. Intramyocardial fibrosis (IF) is associated with this risk. The gold standard of IF visualization is cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE–CMR). In view of a number of CMR-limitations the hypothesis of this study was that late enhanced multi-slice computed tomography (leMDCT) enables demonstration of late enhancement (LE) indicating IF. In a prospective single-center validation study leMDCT research-scans were exclusively performed for IF-imaging in HCM-patients not including non-invasive coronary angiography during first-pass (64-slice; 80 kV; Iopromide, 150 mL, injected 7 min before scanning). Applying a 17-segment-polar-map short cardiac axis views (multiplanar reformations; 5 mm slice thickness) were analysed in order to exclude/detect, localize and measure LE practicing the manual quantification method if present. Finally, leMDCT and LGE–CMR data were unblinded for intermodal correlation. We included n = 24 patients consecutively (64.0 ± 14.5 years of age). LE was demonstrated by LGE–CMR in n = 14/24 patients (prevalence 58 %). Patient- and segment-based sensitivity in leMDCT was 100 and 68 %, respectively. In leMDCT tissue density of LE was 142 ± 51 versus 89.9 ± 19.3 HU in remote myocardium (p < 0.001). Signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) appeared to be 7.3 ± 3.3 and 2.3 ± 1, respectively. Sizing of LE-area gave 2.2 ± 1.4 cm² in leMDCT versus 2.9 ± 2.4 cm² in LGE–CMR (r = 0.93). Intra-/interobserver variability was assessed with an accuracy of 0.36 cm² (r = 0.91) and 0.47 cm² (r = 0.82), respectively. In consecutive HCM patients leMDCT can reliably detect intramyocardial fibrosis marked by LE. In view of a comparatively low SNR and CNR leMDCT may alternatively be applied in case of CMR contraindications.