131碘-间位碘代苄胍心肌显像探测急性心肌梗死后心脏交感神经分布和活力的变化

131 I-MIBG myocardial imaging for detecting the distribution and activity of cardiac sympathetic nerve in acute myocardial infarction

目的通过心脏交感神经受体显像探测急性心肌梗死（AMI）后心脏交感神经的分布和活力。方法AMI组12例，男性11例，女性1例，年龄42～68岁，平均年龄（48±9）岁。对照组6名，男性4名，女性2名，年龄40～66岁，平均年龄（47±6）岁，为健康受试者。AMI组在AMI后2周、3个月及6个月时均行^131碘-间位碘代苄胍（^131I-MIBG）受体显像及^99m 锝-甲氧基异丁基异腈（^99m Tc—MIBI）心肌灌注显像（MPI），对照组在1周内完成^131 I—MI—BG受体显像及^99mTc-MIBI MPI。分析^131 I-MIBG及^99m Tc—MIBI显像相同部位心肌节段的放射性分布，并利用感兴趣区（ROI）技术测定心肌与纵隔放射性比值（H／M）及MIBG的洗脱率（WR）。结果（1）AMI组^131 I-MIBG显像的放射性稀疏．缺损节段数为32个，而^99m Tc—MIBI显像的仅为24个。（2）AMI组在AMI后2周、3个月及6个月和对照组的^131 I-MIBG显像H／M比值为（1．45±0．20）、（1．65±0．16）、（1．70±0．17）和（2．70±0．32），WR为32％、19％、15％和9．5％。AMI组各时间点的H／M和WR与对照组比较差异均有统计学意义（均为P〈0．05）；AMI组2周分别与3个月和6个月比较，差异均有统计学意义（均为P〈0．05）。结论AMI后交感神经受损区域明显大于MPI所显示的受损区域。AMI后心肌交感神经受体下调，表现为MIBG摄取减低；体内交感神经紧张度增高，表现为MIBG滞留时间短、洗脱率高。AMI后3～6个月内交感神经有不同程度的恢复。

Objective To detect the distribution and activity of cardiac sympathetic nerve in acute myocardial infarction （AMI） by cardiac sympathetic nerve receptors imaging. Methods A total of 12 patients with AMI （mean age 48 ±9 years; 1 woman, 11 men） were as experimental group （AMI group）, while 6 healthy volunteers （mean age 47 ±6 years; 2 women, 4 men） were as control group. ^99mTc-methoxyisobutylisonitrile myocardial perfusion imaging （^99mTc-MIBI MPI） and ,^131 I-metaiodobenzylguanidine （^131I-MIBG） were implemented 2 weeks （A2W）, 3 （A3M） and 6 months （A6M） after AMI in AMI group and in control group within 1 week. The radioactivity of same segments of myocardium was analyzed, while the heart/mediastinum （H/M） uptake ratio and wash out rate （WR） of MIBG were determined by region of interest （ROI）. Results ^131 I-MIBG showed 32 myocardial radioactivity sparseness and defect segments, while ^99mTc- MIBI MPI showed only 24 segments in AMI group. The ^131I-MIBG imaging H/M uptake ratio and WR in the AMI group at A2W, A3M, A6M and in control group were 1.45 ± 0. 20, 1.65 ± 0. 16, 1.70 ± 0. 17 and 2. 70 ± 0. 32; 32%, 19%, 15% and 9. 5% , respectively. There were significant differences between AMI group and control group, between A2W and A3M or A6M （ all P 〈 0. 05 ）. Conclusions The sympathetic damaged area determined by ^131I-MIBG imaging is bigger than the area showed by ^99mTc-MIBI imaging. AMI results in cardiac muscle adrenergic neuroreceptor decreasing. Retention time of MIBG is shortened and WR is elevated in AMI as tensity of adrenergic nerve increases in vivo. There is a restoration of sympathetic activity in the infarct area 3-6 months after AMI.