Incremental prognostic value of perfusion defects in patients with scintigraphic evidence of left ventricular dysfunction

Patients with LV dysfunction are known to have a high risk for future coronary events. This study aimed to determine the incremental prognostic value of perfusion defects in patients with scintigraphic evidence of LV dysfunction. Patients showing either transient ischemic dilatation or Tl-201 lung:heart ratio of >0.5 on exercise or dipyridamole SPECT Tl- 201 myocardial perfusion scan were included in the study. Perfusion defects were scored semiquantitatively using a 17 -segment, 5-point scale (0 = normal, 4 = absent uptake). The extent and severity of defects were quantified using number of abnormal segments (NAS) and the summed stress score (SSS). Defect reversibility was quantified using the summed difference score (SDS) between stress and rest defects. Patients were followed up for the development of coronary events over a period of 12 - 30 months. There were 6 cardiac deaths and 7 myocardial infarctions in the 65 patients included in the study (20% overall event rate). ROC curve analysis of the scores revealed the following suggested cut-off values for predicting cardiac event: NAS ~ 7 (85% sensitivity, 56% specificity), SSS ~ 19 (77% sensitivity, 67% specificity) and SDS ~ 7 (31 % sensitivity, 60% specificity). ,Event rate was significantly higher above the cut-off value in SSS «19 = 9%, >19 = 32%,p = 0.04). With NAS, the event rate was higher above the cut-off value, with the difference approaching significance (NAS 7 = 26%, P = 0.06). There was no statistically significant difference in the event rate with high or low SDS (SDS 7 = 16%, P = 0.32). The odds ratios for NAS and SSS (5.8,4.9, respectively) were higher compared with SDS (0.56). The extent and severity of stress perfusion defects provided incremental prognostic information in patients with LV dysfunction. Our data suggest that the degree of defect reversibility showed no prognostic value in this subset of patients.

Prediction of Histologic Grade and Multidrug Resistance of Brain Tumors Using Brain SPECT

OBJECTIVE: Computerized tomography(CT) and magnetic resonance imaging(MRI) are very useful in detection of structural change in the brain including tumors. However, they can not inform functional and biological behavior of such lesions. 99m Tc-Methoxyisobutyl isonitrile(MIBI) is considered as a substrate for MDR1 gene-encoded permeability glycoprotein(P-gp) and it has been used in the evaluation of multidrug resistance(MDR) in various tumors. The purpose of the study is to demonstrate the presence of MDR in brain tumor and brain tumor grading by an external imaging with 201Thallium and 99m Tc-MIBI SPECT. METHODS: 201Thallium and 99m Tc-MIBI SPECT were performed in 18 patients with malignant tumors and in six patients with benign tumors. Immunohistochemical staining(IHC) of the tumor specimen for P-gp was also performed. The histologic grading of the tumors and immunohistochemical staining for P-gp were compared to the dual brain SPECT findings of 201Thallium and 99m Tc-MIBI SPECT studies. Brain tumor with positive 201Thallium SPECT and negative 99m Tc-MIBI SPECT is considered to be multidrug resistance. An uptake index obtained from brain SPECT was used for tumor grading. MDR1 gene-encoded P-gp was assessed by immunohistochemical staining using a monoclonal antibody for P-gp. RESULTS: The malignant group showed significantly higher uptake indices in the 201Thallium and 99m Tc-MIBI SPECT than benign group. The uptake index of 99m Tc-MIBI SPECT was inversely correlated with P-gp immunohistochemical staining without statistical significance. CONCLUSION: 201Thallium and 99m Tc-MIBI SPECT are useful for predicting histologic grade of brain tumors, and 99m Tc-MIBI SPECT might be useful for predicting the presence of MDR protein.

Reproducibility of Gated Myocardial Perfusion SPECT for the Assessment of Myocardial Function : Comparison with Thallium-201 and Technetium-99m-MIBI / 대한핵의학회잡지

PURPOSE: We compared the reproducibility of 201Tl and 99mTc-sestamibi (MIBI) gated SPECT measurement of myocardial function using the Germano algorithm. MATERIALS AND METHODS: Gated SPECT acquisition was repeated in the same position in 30 patients who received 201Tl and in 26 who received 99mTc-MIBI. The quantification of end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) on 201Tl and 99mTc-MIBI gated SPECT was processed independently using Cedars quantitative gated SPECT software. The reproducibility of the assessment of myocardial function on 201Tl gated SPECT was compared with that of 99mTc-MIBI gated SPECT. RESULTS: Correlation between the two measurements for volumes and EF was excellent by the repeated gated SPECT studies of 201Tl (r=0.928 to 0.986; p<0.05) and 99mTc-MIBI (r=0.979 to 0.997; p<0.05). However, Bland Altman analysis revealed the 95% limits of agreement (2 SD) for volumes and EF were tighter by repeated 99mTc-MIBI gated SPECT (EDV: 14.1 ml, ESV: 9.4 ml and EF: 5.5%) than by repeated 201Tl gated SPECT (EDV: 24.1 ml, ESV: 18.6 ml and EF: 10.3%). The root mean square (RMS) values of the coefficient of variation (CV) for volumes and EFs were smaller by repeated 99mTc-MIBI gated SPECT (EDV: 2.1 ml, ESV: 2.7 ml and EF: 2.3%) than by repeated 201Tl gated SPECT (EDV: 3.2 ml, ESV: 3.5 ml and EF: 5.2%). CONCLUSION: 99mTc-MIBI provides more reproducible volumes and EF than 201Tl on repeated acquisition gated SPECT. 99mTc-MIBI gated SPECT is the preferable method for the clinical monitoring of myocardial function.