The effect of aminophylline administration on 99mTc-MIBI lung and liver uptake in patients with or without myocardial ischemia

Abstract

This work aims to analyze the influence of aminophylline in the pulmonary and hepatic uptake of 99mTc-methoxyisobutil isonitrile (99mTc-MIBI). 72 patients were studied and a myocardial perfusion (MPS) single photon emission computed tomography (SPECT) with 99mTc-MIBI was carried out after the administration of dipyridamole. According to the MPS, the patients were classified into 2 groups: Group A: 45 patients without myocardial ischemia and Group B: 27 with ischemia. Each group was divided into 2 subgroups according to whether they had (I) or had not (II) received intravenous aminophylline. The dipyridamole was administered for 4 minutes at a dose of 0.56 mg/kg. If the patients presented any complication, intravenous aminophylline was administered. At 30 minutes p.i., planar images were obtained during a scintigraphy in the interior projection after the injection of 99mTc-MIBI. The regions of interest in the heart, hepatic cupula, and most active area of the left lung were outlines and the activity rates were calculated: lung/heart (LHR) and liver/heart (LivHR). No statistically significant differences were observed in the uptake of 99mTc-MIBI between subgroups I and II. However, the LHR rates in both subgroups were significantly lower in the patients with normal myocardial perfusion than in the patients with ischemia: LHR group A1 vs B1: 0. 32 +/- 0.08 vs 0.36 +/- 0.06, p = 0.03; group AII vs BII 0.31 +/- 0. 07 vs 0.35 +/- 0.07, p = 0.01 respectively. In conclusion, the administration of aminophylline, after the infusion of dipyridamole for MPS, does not modify the pulmonary or hepatic uptake of 99mTc-MIBI.