Cardiac Magnetic Resonance Imaging (CMRI) for Detection of Cardiac Transplant Rejection

Objectives To find a non-invasive alternative (with using cardiac MRI) to invasive endomyocardial biopsies for serial detection and follow-up of cellular rejection in heart transplant in childhood.

Background Detection of cardiac rejection is a major problem in cardiac transplantation. Invasive screenings at predefined time intervals for cellular rejection with using endomyocardial biopsies are standard procedures. However, cardiac biopsies are distressing and risky and are also costly. Moreover, as the histological expression of allograft rejection is patchy, endomyocardial biopsies may lead to sampling error. Thus, as the sensitivity is low and variable (range for 40 to 95%), indication of biopsy is still of debate.

Materials and methods All patients who undergone cardiac transplant are potentially eligible. They will be prospectively included in the study. They will have both examinations, their routine endomyocardial biopsies and cardiac MRI. Histological diagnosis of cellular rejection is given by the BILLINGHAM classification which is used in daily practice. Diagnosis of rejection of cardiac MRI is defined by the association of hyperintensity on T2-weighted sequence, and on gadolinium-enhanced sequences including SSFP (study state free precession) and myocardial delayed enhancement. Both MRI parameters attest of the presence of myocardial oedema related to acute rejection. Myocardial oedema is also associated with segmental abnormalities of myocardial contraction which is assessed by both CMR-tagged sequence.

Written informed consent will be required from the patients. Institutional review board approval will also be required.

Expected results and clinical implications We expect to demonstrate that CMRI is effective for detection of cellular rejection with a high sensitivity (expected sensitivity>95%) as compared to cardiac biopsy. In that condition, cardiac MRI could replace the invasive biopsy for serial detection and follow-up of rejection in heart transplant.