High-resolution Free-breathing late gadolinium enhancement Cardiovascular magnetic resonance to diagnose myocardial injuries following COVID-19 infection

Abstract

Purpose: High-resolution free-breathing late gadolinium enhancement (HR-LGE) was shown valuable for the diagnosis of acute coronary syndromes with non-obstructed coronary arteries. The method may be useful to detect COVID-related myocardial injuries but is hampered by prolonged acquisition times. We aimed to introduce an accelerated HR-LGE technique for the diagnosis of COVID-related myocardial injuries.

Method: An undersampled navigator-gated HR-LGE (acquired resolution of 1.25 mm³) sequence combined with advanced patch-based low-rank reconstruction was developed and validated in a phantom and in 23 patients with structural heart disease (test cohort; 15 men; 55 ± 16 years). Twenty patients with laboratory-confirmed COVID-19 infection associated with troponin rise (COVID cohort; 15 men; 46 ± 24 years) prospectively underwent cardiovascular magnetic resonance (CMR) with the proposed sequence in our center. Image sharpness, quality, signal intensity differences and diagnostic value of free-breathing HR-LGE were compared against conventional breath-held low-resolution LGE (LR-LGE, voxel size 1.8x1.4x6mm).

Results: Structures sharpness in the phantom showed no differences with the fully sampled image up to an undersampling factor of x3.8 (P > 0.5). In patients (N = 43), this acceleration allowed for acquisition times of 7min21s ± 1min12s at 1.25 mm³ resolution. Compared with LR-LGE, HR-LGE showed higher image quality (P = 0.03) and comparable signal intensity differences (P > 0.5). In patients with structural heart disease, all LGE-positive segments on LR-LGE were also detected on HR-LGE (80/391) with 21 additional enhanced segments visible only on HR-LGE (101/391, P < 0.001). In 4 patients with COVID-19 history, HR-LGE was definitely positive while LR-LGE was either definitely negative (1 microinfarction and 1 myocarditis) or inconclusive (2 myocarditis).

Conclusions: Undersampled free-breathing isotropic HR-LGE can detect additional areas of late enhancement as compared to conventional breath-held LR-LGE. In patients with history of COVID-19 infection associated with troponin rise, the method allows for detailed characterization of myocardial injuries in acceptable scan times and without the need for repeated breath holds.

Keywords: COVID-19; Cardiac Magnetic Resonance Imaging; High-resolution; Late Gadolinium Enhancement.

Fig. 1

Schematic overview of investigated free-breathing motion-corrected three-dimensional (3D) whole-heart high-resolution myocardial LGE framework (HR-LGE). A non-selective inversion recovery (IR) pulse is applied immediately after electrocardiogram (ECG) R wave. Image acquisition is gated to account for the diaphragmatic respiratory displacement of the heart. A variable-density Cartesian undersampling is used to achieve clinically feasible scanning times (undersampling factor of x3.8). The HR-LGE volume is reconstructed with an undersampled patch-based low-rank reconstruction exploiting local patch similarities in the 3D volume. Abbreviations: FAT SAT = fat saturation, k_x = readout, k_y = phase encoding, k_z = slice encoding, TI = inversion time.

Fig. 2

Patch-based low-rank reconstructions of the resolution phantom for different undersampling factors. Reconstructed images exhibit sharp edges with faithful preservation of small details for undersampling factors up to x3.8 (as shown on the cross-section profiles).

Fig. 3

Comparisons of reformatted free-breathing 3D HR-LGE and breath-held 3D LR-LGE in three patients (test cohort) with ischemic and non-ischemic LGE patterns. Yellow arrows indicate LGE, red arrows indicate artifacts on LR-LGE. Patient 1: 33-year-old male patient with hypertrophic cardiomyopathy associated with sub-epicardial and midwall LGE. Patient 2: 56-year-old male patient with ischemic cardiomyopathy showing transmural LGE in the right coronary artery and mid-left anterior descending artery territories. Patient 3: 75-year-old male patient presenting with severe hypokinesia and transmural myocardial infarction in the right coronary artery territory.

Fig. 4

Comparisons of reformatted free-breathing 3D HR-LGE and breath-held 3D LR-LGE in four patients (test cohort) presenting with various patterns of enhancement. Yellow arrows indicate LGE. Patient 4: 70-year-old man with hypertrophic cardiomyopathy associated with focal fibrosis. Patient 5: 62-year-old woman with inferior and inferoseptal myocardial infarction. Patient 6: 45-year-old man with arrhythmogenic right ventricular dysplasia, showing focal septal LGE. Patient 7: 48-year-old male patient with focal sub-endocardial LGE consistent with micro-infarction in the left anterior descending artery territory.

Fig. 5

Image quality comparisons between conventional breath-held low-resolution LGE (LR-LGE) and the proposed free-breathing high-resolution LGE (HR-LGE, reformatted images) sequence in four patients with laboratory-confirmed COVID-19 infection associated with troponin rise. The final diagnoses were negative CMR (top left), myocardial infarction (bottom left), acute myocarditis (top right and bottom right). Yellow arrows indicate sites of LGE.

Fig. 6

Spectrum of myocardial injuries on reformatted free-breathing high-resolution LGE after COVID-19 infection. Yellow arrows indicate areas with LGE. A: intramural and sub-epicardial LGE on the anterio-lateral and infero-septal segments, consistent with myocarditis. B: subepicardial LGE on infero-basal and infero-latero-basal segments, consistent with myocarditis. C: focal subendocardial LGE on antero-septal segment consistent with micro-infarction. D: focal subendocardial LGE on antero-lateral segment consistent with micro-infarction.