King's College London

Background

CMRA in pediatrics remains challenging due to the smaller vessel size, high heart rates (HR), potential image degradation caused by limited patient cooperation and long acquisition times. High-relaxivity contrast agents have been shown to improve coronary imaging in adults, but limited data is available in children. We sought to investigate whether gadobenate dimeglumine (Gd-BOPTA) together with self-navigated inversion-prepared coronary magnetic resonance angiography (CMRA) sequence design improves coronary image quality in pediatric patients.

Methods

Forty consecutive patients (mean age 6 ± 2.8 years; 73% males) were prospectively recruited for a 1.5-T MRI study under general anesthesia. Two electrocardiographic-triggered free breathing steady-state free precession (SSFP) angiography sequences (A and B) with isotropic spatial resolution (1.3 mm³) were acquired using a recently developed image-based self-navigation technique. Sequence A was acquired prior to contrast administration using T2 magnetization preparation (T2prep). Sequence B was acquired 5–8 min after a bolus of Gd-BOPTA with the T2prep replaced by an inversion recovery (IR) pulse to null the signal from the myocardium. Scan time, signal-to noise and contrast-to-noise ratios (SNR and CNR), vessel wall sharpness (VWS) and qualitative visual score for each sequence were compared.

Results

Scan time was similar for both sequences (5.3 ± 1.8 vs 5.2 ± 1.5 min, p = .532) and average heart rate (78 ± 14.7 vs 78 ± 14.5 bpm, p = .443) remained constant throughout both acquisitions. Sequence B resulted in higher SNR (12.6 ± 4.4 vs 31.1 ± 7.4, p < .001) and CNR (9.0 ± 1.8 vs 13.5 ± 3.7, p < .001) and provided improved coronary visualization in all coronary territories (VWS A = 0.53 ± 0.07 vs B = 0.56 ± 0.07, p = .001; and visual scoring A = 3.8 ± 0.59 vs B = 4.1 ± 0.53, p < .001). The number of non-diagnostic coronary segments was lower for sequence B [A = 42 (13.1%) segments vs B = 33 (10.3%) segments; p = .002], and contrary to the pre-contrast sequence, never involved a proximal segment. These results were independent of the patients' age, body surface area and HR.

Conclusions

The use of Gd-BOPTA with a 3D IR SSFP CMRA sequence results in improved coronary visualization in small infants and young children with high HR within a clinically acceptable scan time.

AbbreviationsBP-CA, blood pool contrast agent; BSA, body surface area; SSFP, steady state free precession; CHD, congenital heart disease; CMR, cardiovascular magnetic resonance; CMRA, coronary magnetic resonance angiography; CNR, contrast-to-noise ratio; CoA, aortic coarctation; EC-GBCA, extra-cellular gadolinium-based contrast agent; ECG, electrocardiogram; Gd-BOPTA, gadobenate dimeglumine; HR, heart rate; iNAV, image-based navigator; IR, inversion recovery; LAD, left anterior descending artery; LCx, left circumflex artery; MRI, magnetic resonance imaging; RCA, right coronary artery; SNR, signal-to-noise ratio; VWS, vessel wall sharpness.