99 mTc-MIBI washout as a complementary factor in the evaluation of idiopathic dilated cardiomyopathy (IDCM) using myocardial perfusion imaging

Abstract

Rapid technetium-99 m methoxyisobutylisonitrile (99 mTc-MIBI) washout has been shown to occur in impaired myocardia. This study is based on the hypothesis that scintigraphy can be applied to calculate the myocardial 99 mTc-MIBI washout rate (WR) to diagnose and evaluate heart failure severity and other left ventricular functional parameters specifically in idiopathic dilated cardiomyopathy (IDCM) patients. Patients with IDCMP (n = 17; 52.65 ± 11.47 years) and normal subjects (n = 6; 49.67 ± 10.15 years) were intravenously administered 99 mTc-hexakis-2-methoxyisobutylisonitrile (99 mTc-MIBI). Next, early and delayed planar data were acquired (at 3.5-h intervals), and electrocardiogram (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT) was performed. The 99 mTc-MIBI WR was calculated using early and delayed planar images. Left ventricular functional parameters were also analyzed using quantitative gated SPECT (QGS) data. In target group, myocardial WRs (29.13 ± 6.68%) were significantly higher than those of control subjects (14.17 ± 3.31%; P < 0.001). The 99 mTc-MIBI WR increased with the increasing severity of the NYHA functional class (23.16 ± 1.72% for class I, 30.25 ± 0.95% for class II, 32.60 ± 6.73% for class III, and 37.50 ± 7.77% for class IV; P = 0.02). The WR was positively correlated with the end-diastolic volume (EDV) index (r (2) = 0.216; β = 0.464; P = 0.02 [ml/m(2)], the end-systolic volume (ESV) index (r (2) = 0.234; β = 0.484; P = 0.01 [ml/m(2)]), the summed motion score (SMS) (r (2) = 0.544; β = 0.738; P = 0.00), and the summed thickening score (STS) (r (2) = 0.656; β = 0.810; P = 0.00); it was negatively correlated with the left ventricular ejection fraction (LVEF) (r (2) = 0.679; β = -0.824; P = 0.00). It can be concluded that 99 mTc-MIBI scintigraphy might be a valuable molecular imaging tool for the diagnosis and evaluation of myocardial damage or dysfunction severity.

99mTc-MIBI Lung Scintigraphy in the Assessment of Pulmonary Involvement in Interstitial Lung Disease and Its Comparison With Pulmonary Function Tests and High-Resolution Computed Tomography

“…Additionally, it appears to have a role in the diagnosis and staging of tumors, and in the noninvasive assessment of ischemia in patients with peripheral vascular diseases. 27 Results from the present study indicate that the lung uptake of 99mTc-MIBI was well-correlated with markedly abnormal in patients with ILD who had clinical and/or radiologic evidence of pulmonary involvement.…”

MIBI and Mitochondria

“…The heart-to-mediastinal ratio was calculated from planar images recorded at 40 min and at 4 h. The investigators found increased MIBI loss from the myocardium in patients with elevated left ventricular end-diastolic pressure and prolonged half-time of relaxation. In 17 patients with dilated cardiomyopathy (mean LVEF: 29%), Shiroodi et al (15) measured MIBI washout and compared the results to those from 6 normal subjects (mean LVEF: 66%). The investigators acquired images at 30 min and 3.5 h after injection.…”

“…Hayashi et al (16) used a slightly different protocol than did Shiroodi et al (15), recording MIBI images at 1 and 4 h after injection. Myocardial retention of MIBI was measured on planar images as: (initial net myocardial counts* -delayed net myocardial counts † )/initial net myocardial counts.…”

Additional applications of approved radiopharmaceuticals for nuclear cardiology

“…The heart-to-mediastinal ratio (HMR) was calculated from planar images recorded at 40 min and at 4 h. The investigators found increased MIBI loss from the myocardium in patients with elevated left ventricular end-diastolic pressure and prolonged half time of relaxation. In 17 patients with dilated cardiomyopathy (LVEF 29 %), Shiroodi and colleagues [26] measured MIBI washout and compared the results to six normal subjects (LVEF 66 %). Myocardial clearance was measured as the change in HMR at 30 min and 3.5 h after injection.…”