Serial T2-mapping to quantitatively monitor resorption of myocardial edema following acute myocardial infarction

Background

Currently, myocardial edema monitoring after acute myocardial infarction (AMI) is based on visualization of the region with increased signal-intensity on T2-weighted images. T2-mapping is a promising novel cardiac magnetic resonance imaging (CMR) technique to quantitatively assess myocardial edema. The purpose of the study was to quantitatively evaluate resorption of myocardial edema following AMI using T2-mapping.

Methods

CMR (1.5 Tesla Philips Achieva) was performed in 20 patients within seven days after a reperfused AMI (Baseline) and at one, three and six months follow-up, respectively. A free-breathing, navigator-gated multi-echo sequence was used for T2-mapping. T2-maps were calculated from fifteen echoes using a dedicated plug-in written for OsiriX software. Serial T2 values were assessed using a six-segment model (Figure). Infarcted and remote segments were defined by using information from corresponding late-enhancement images (Figure).

Figure 1

CMR of a patient with acute posterior infarction. The infarct and the myocardial edema is seen on the DE- and the T2w-CMR, respectively. The T2-Map shows increased T2 time in the infarcted area. A segmental evaluation was performed in six segments.

Results

A significant decrease of the T2 time was found in infarcted segments from baseline to one month follow-up (82±19 vs. 70±7 ms; p<0.05), but not between one and three (70±7 vs. 62±8; p=ns) or three and six (62±8 vs. 62±5 ms; p=ns) month follow-up. Identical T2 times were found in remote segments at baseline, one, three and six month follow-up (61±6 vs. 61±5 vs. 59±7 vs. 58±2 ms; p=ns). The T2infarct/T2remote ratio decreased from baseline to one month follow-up (1.34±0.26 vs. 1.15±0.10; p<0.05) and from one to three month follow-up (1.15±0.10 vs. 1.04±0.06; p=0.05). No significant change was found for the T2infarct/T2remote ratio from three to six month follow-up (1.04±0.06 vs. 1.07±0.09; p=ns).

Conclusions

Serial T2-mapping enables monitoring of edema resorption following acute myocardial infarction. The magnitude of edema resorption occurs in the first month after AMI and the T2 values normalize within 3 months after AMI. Thereafter, no further T2 time reduction is observed.

Funding

None