Abstract
Cardiovascular magnetic resonance (CMR) has been studied as an alternative to endomyocardial biopsy (EMB) in orthotopic heart transplant recipients (OHTRs), particularly through breath-hold myocardial T1 and T2 mapping sequences. We aimed to assess the diagnostic performance of the novel free-breathing multiparametric saturation-recovery single-shot acquisition (mSASHA) mapping technique to identify acute cardiac allograft rejection (ACAR) non-invasively against EMB. This retrospective study included n = 21 consecutive OHTRs with suspected ACAR who underwent both a 1.5T CMR scan with mSASHA mapping and an EMB within 5.4 (1.2-14.8) days, and n = 20 healthy controls who underwent CMR with mSASHA mapping. Conventional breath-holding T2-prepared balanced steady-state free precession (T2p-bSSFP) T2 mapping was also acquired. CAR was EMB defined as histological rejection (HR) (acute cellular rejection of ≥ 1 R or acute antibody-mediated rejection of ≥ 1). Overall, n = 21 OHTRs (9 females) with a mean age of 43.2 ± 16.2 years and a median time of 5.4 (1.2-14.8) years since transplantation were included in the study, alongside n = 20 healthy controls. HR was present in n = 9 patients. The HR group showed significantly higher septal mSASHA T2 values compared to the non-HR (n = 12) group (53 ± 6 ms vs. 47 ± 4 ms, p = 0.014). Receiver operator characteristics analysis showed an area under the curve of 0.79 (95% confidence interval 0.59-0.98, p = 0.028) and an optimal cut-off value of 50 ms (sensitivity of 67%, specificity of 75%) for identifying patients with HR using septal mSASHA T2 values. There was at least a moderate correlation of septal and global mSASHA T1 and T2 values (n = 21) with MOLLI T1 (n = 17) and T2p-bSSFP T2 (n = 18) values (r > 0.6, p ≤ 0.003). OHTR patients without HR showed higher septal (T1: 1256 ± 42 ms vs. 1201 ± 46 ms, p = 0.002; T2: 47 ± 4 ms vs. 43 ± 2 ms, p = 0.003) and global mSASHA (T1: 1250 ± 58 ms vs. 1201 ± 45 ms, p = 0.013; T2: 48 ± 5 ms vs. 43 ± 2 ms, p = 0.009) values compared to normal controls (n = 20). In the control group, native mSASHA T1 and T2 values were higher in females (n = 9) than in males. Free-breathing mSASHA T2 mapping may be useful in identifying histological changes associated with ACAR, overcoming the challenges of breath holding and with good diagnostic performance.