Estimation of destruction of necrotic myocardium with serial PYP SPECT images and serum myosin light chain I level

PYP SPECT images were underwent in 15 patients with acute myocardial infarction 2-5 times in three weeks. PYP SPECT images were reconstructed as to include both vertebral images and myocardial images. Quantitative estimation of PYP images was performed by the ratio of maximal PYP myocardial uptake to maximal PYP vertebral uptake in the central sagittal images (%PYP). Disappearance of PYP images was defined as the day, when %PYP reached 50%. Normalization of serum myosin light chain I (LCI) level was defined as the day, when LCI level reached 2.5 ng/ml. %PYP decreased continuously and maximal PYP point remained at the same area. Shape of PYP images varied and diminished. In case of anterior wall infarction apical PYP uptake persisted longer than basal uptake. In case of inferior wall infarction basal PYP uptake persisted longer than apical uptake. The mean period from onset to the disappearance of PYP images was 9±3 days. Pattern of serial serum MB level was simple, however corresponding pattern of serial serum LCI level showed various types. The mean period from onset to the peak level was 4.1±1 day. Normalization of LCI level was 9.3±2.9 days. It showed that process of destruction of necrotic myocardium vary in each case. Weak relation was noted between disappearance of PYP images (DAY-PYP) and normalization of LCI level (DAY-LCI). DAY-PYP=4.4+0.46 DAY-LCI (n=13, r=0.4). Quantitative PYP images were useful for detecting ongoing necrotic myocardium and serum LCI level was useful for estimating destruction of necrotic myocardium. PYP images and serum LCI level were useful to study the process of destruction of necrotic myocardium. (author)