Abstract 15364: Cardiac Magnetic Resonance T1 Mapping Pre and Post Contrast Characterizes the Myocardium in Orthotopic Heart Transplantation Recipients without Active Rejection

Abstract

Background Transplant rejection is characterized by interstitial inflammatory infiltrate and damage followed by apoptotic death of interstitial cells and myocytes. This inflammatory reaction is followed by both replacement fibrosis and interstitial fibrosis which in the long term can impair diastolic and systolic ventricular (LV) function.Cardiac magnetic resonance (CMR) with gadolinium quantifies replacement fibrosis and compares well with biopsy in the diagnosis of heart transplant rejection. New sequences with T1 mapping are proposed for the quantification of interstitial fibrosis .

Methods We studied 9 heart transplant patients (Tx), mean time from Tx 64±58 mo (range 6÷174) and 5 normals (N), age 58±7 and 45±9. CMR was performed on a 1.5 Tesla scanner (Siemens). Short axis SSFP cine images covering the LV were acquired; image position was used for T2-(STIR), T1-mapping and late gadolinium enhancement (LGE). ShMOLLI T1 maps were generated from 5-7 SSFP images with variable inversion preparation time as described by Piechnik (2010) before and after gadobutrol i.v. (0.15 mmol/kg). Region of interest were drawn on 3 short axis (base,mid,apex) average T1 values msec were fitted by a non-linear curve. Data are mean±SD

Results Systolic function was similar in both groups Tx 65±9 vs N 67±8 p=0.69, LV Mass Index was slightly higher in Tx 84±22 vs 69±5 N p=0.3. In Tx pre -contrast T1 was longer 1036±98 vs 958±44 msec p<0.001 , whereas post contrast was shorter 396±44 msec vs 453±40 msec p<0.001. The ratio pre T1/post T1 was significantly greater in Tx 2.6±0.4 vs 2.1±0.2 p<0.05. T1 post-contrast but not pre-contrast was correlated to time interval from Tx y=491-26_*lnx ; p<0.05. The pre/post ratio was correlated to LVMI y=1536+0.13_*x; p<0.05. Seven out of 9 Tx had patchy LGE distribution, 1 had a previous myocardial infarction and 1 did not show LGE. STIR signal intensity was 2.1±0.6 p=ns vs N.

Conclusions Patient transplanted with no active rejection show a significant increase of interstitial fibrosis which builds up over time. Beside anatomo-functional parameters the combination of LGE and T1 mapping can provide a useful non invasive characterization of the collagen deposition in transplanted hearts and allow a better insight into the progression of adverse remodeling.