Feasibility of a Noncontrast Rapid Cardiac Magnetic Resonance Imaging Protocol in Heart Transplant Recipients for Detection of Acute Cardiac Allograft Rejection

The recommended method of diagnosing acute cardiac allograft rejection (ACAR) is endomyocardial biopsy (EMB). The objective of this study was to assess the feasibility of rapid cardiac magnetic resonance (CMR) imaging protocol, which substantially reduces the scan times and increases the cost-effectiveness, for surveillance in heart transplant (HTx) recipients. Thirty HTx recipients underwent noncontrast CMR the day prior to scheduled routine EMB. Acquisitions were done on a 1.5 Tesla scanner (Siemens Magnetom Aera) with a truncated rapid protocol consisting of a Trufi stack, cine imaging, and mapping. Thirty normal controls were also scanned. The average time per scan was 9.4 ± 1.22 minutes. The average native T1 and T2 mapping values were significantly higher in HTx recipients than controls (p = 0.002 and p = 0.02, respectively). Patients with ACAR had significantly increased native T1 (1080.29 ± 30.5 ms) and T2 (56.01 ± 4.67 ms) compared with HTx recipients without ACAR (T1: 1016.07 ± 38.23 ms; T2: 49.07 ± 3.72 ms) (p = 0.001 and 0.0001, respectively). The area under the curve for T1 and T2 mapping to diagnose ACAR were 0.92 and 0.86, respectively. The sensitivity and specificity of native T1 (cutoff: 1033.655 ms) for diagnosing ACAR were 84.2 and 100 %, respectively, and that of T2 mapping (cutoff: 53.34 ms) were 77.2 and 89.5%, respectively. We demonstrated the feasibility of a rapid truncated noncontrast CMR protocol for the surveillance of HTx recipients for the detection of ACAR.