Cardiac disease has a high incidence in patients undergoing long term hemodialysis. The survival rate is influenced by myocardial function, left ventricular (LV) ejection fraction (EF), severity of LV dilatation and hypertrophy which can be accurately determined by MR imaging. Autopsy studies revealed that myocardial fibrosis is an additional factor for LV functional impairment. This study investigates Gd-DTPA contrast enhanced MR imaging in correlation to myocardial morphology and function to detect fibrotic myocardial changes in patients with end-stage renal disease (ESRD).
METHOD AND MATERIALS
Ten healthy volunteers and 25 patients with ESRD were examined at 1.5T (Magnetom Sonata, Siemens) including cine trueFISP 2D and contrast enhanced inversion-recovery prepared segmented turboFLASH sequences (0.15 mmol Gd-DTPA/kg). Based on a 16 segment model of the LV and 6 segment model of the RV an individual score was determined by segmentally rating myocardial contrast enhancement from 0 (=normal) to 3 (=markedly elevated) for each study subject. Contrast to noise (CNR) was measured in reference regions of interest and regions with visually detectable enhancement. EF, LV mass and end-diastolic volumes (EDV) were calculated based on the modified Simpson rule.
Patchy, stripe like or focal endocardial contrast enhancement of the LV was present in 22/25 and of the RV in 10/25 patients (volunteers 6/10 and 2/10). The following parameters were found in patients/ volunteers: EDV 146±47ml/117±38ml (p<0.001), LV mass 144±46g/92±31g (p<0.001), mean rating of segmental enhancement 0.84±0.98/0.30±0.47 (p<0.001), mean score 13.08±8.53 (range 0-31)/4.60±3.58 (range 0-9, p<0.001), CNR 3.08±2.77/1.2±0.8 (p<0.001). Close correlation was found comparing EF and CNR (r=0.75, p<0.0001). Intermediate correlation was observed for enhancement score and EF (r=0.52, p<0.008).
Increased CNR and different types of focal contrast enhancement can be detected in patients with ESRD. We suppose that these findings are consistent with focal and/ or diffuse myocardial fibrosis. Close correlation of CNR and EF suggests that the diffuse type is more relevant for cardiac functional impairment than the focal pattern.