Assessment of myocardial viability in chronic coronary artery disease using technetium-99m sestamibi SPECT. Correlation with histologic and positron emission tomographic studies and functional follow-up.

OBJECTIVES: The value of 99mTc-sestamibi (2-methoxy-isobutyl isonitrile [MIBI]) as a viability tracer was investigated in patients undergoing coronary artery bypass graft surgery. BACKGROUND: Initial studies claim that rest MIBI single-photon emission computed tomographic (SPECT) studies can be used to assess myocardial viability. METHODS: Thirty patients with a severely stenosed left anterior descending coronary artery and wall motion abnormalities were prospectively included. The patients underwent a MIBI rest study, a positron emission tomographic (PET) flow (13NH3) and metabolism (18F-deoxyglucose) study and nuclear angiography before undergoing bypass surgery. A preoperative transmural biopsy specimen was taken from the left ventricular anterior wall. Morphometry was performed to assess percent fibrosis. After 3 months, radionuclide angiography was repeated. RESULTS: Statistically significant higher MIBI values were found in the group with myocardial viability as assessed by PET than in the group with PET-assessed nonviability (p < 0.01). Significantly higher MIBI values were found in the group with enhanced contractility at 3 months (76 +/- 13% vs. 53 +/- 22%, p < 0.01). A linear relation was found between MIBI uptake and percent fibrosis in the biopsy specimen (r = 0.78, p < 0.00001). When maximizing the threshold for assessment of viability with MIBI by using functional improvement as the reference standard, a cutoff value of 50% was found, with positive and negative predictive values of 82% and 78%, respectively. CONCLUSIONS: 99mTc MIBI uptake was significantly higher in PET-assessed viable areas and in regions with enhanced contractility at 3 months. A linear relation was found between percent fibrosis and MIBI uptake. An optimal threshold of 50% was found for prediction of functional recovery.

Early assessment of regional myocardial blood flow and metabolism in thrombolysis in myocardial infarction flow grade 3 reperfused myocardial infarction using carbon-11-acetate.

OBJECTIVES: The aim of this study was to investigate the prognostic value of carbon-11-acetate (acetate) positron emission tomography (PET) after successful reperfusion of myocardial infarction (MI). BACKGROUND: Acetate PET allows the measurement of both myocardial flow and oxidative metabolism. The prognostic value of acetate measurements performed early (within 24 h) after Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 reperfused MI is unknown. METHODS: In 18 patients with TIMI flow grade 3 reperfusion of their first MI, a dynamic acetate study was performed within 24 h of the acute event. At five days, nitrogen-13-NH3 (NH3) and fluorine-18-labeled fluorodeoxyglucose (FDG) PET studies were performed. Infarct-related areas were classified as "PET viable" or "PET nonviable," as assessed with NH3 and FDG, according to previously established criteria. At five days and three months, radionuclide angiography was performed for evaluation of left ventricular (LV) function. RESULTS: In infarct-related regions, myocardial blood flow, FDG uptake and oxygen consumption were decreased, compared with remote regions. However, oxygen consumption values, as measured with acetate in both PET-viable and PET-nonviable areas, as assessed with NH3 and FDG, were not significantly different (p = NS). A significant linear correlation was observed between global LV ejection fraction at three months and oxidative metabolism in the infarct-related area (r = 0.8, p < 0.0001). Multivariate analysis revealed that oxidative metabolism measurements in reperfused myocardium was the only significant predictor for recovery of LV function at three months (p < 0.05). CONCLUSIONS: Measurement of oxidative metabolism early after TIMI flow grade 3 reperfusion of MI offers important prognostic value concerning LV function at follow-up.

Tomographic and planar quantitation of perfusion defects on technetium 99m-labeled sestamibi scans: evaluation in patients treated with thrombolytic therapy for acute myocardial infarction.

BACKGROUND: Our segmentation algorithm for single-photon emission computed tomographic perfusion studies was tested in 244 patients treated by thrombolysis within 5 hours after onset of symptoms. This algorithm uses radial slices to approximate true three-dimensional gradients, determines the apex and basal plane, and creates a perfusion and volume polar map. METHODS AND RESULTS: Perfusion defect size was compared with enzymatic infarct size and global and regional function. All patients underwent rest planar and tomographic 99mTc-labeled sestamibi scanning, contrast coronary angiography, and ventriculography 10 to 14 days after the start of treatment. Manual correction had to be performed in only 10% of the cases and presented no problems. The correlation coefficients (r) between planar and relative tomographic perfusion defects versus enzymatic infarct size were 0.71 and 0.73. A negative correlation was found with left ventricular ejection fraction: r = -0.65 and r = -0.60. A comparable correlation was also found between regional wall motion and perfusion defect size. Most correlations were higher in the case of anterior infarction. An excellent correlation was found between planar and tomographic defect size (r = 0.83). CONCLUSIONS: In most cases, our segmentation algorithm delineates myocardial edges and basal plane automatically. A good correlation was found between perfusion defect size, enzymatic infarct size, and global and regional ventricular function.

FDG-PET scan in potentially operable non-small cell lung cancer: do anatometabolic PET-CT fusion images improve the localisation of regional lymph node metastases? The Leuven Lung Cancer Group.

Exact localisation of thoracic lymph nodes (LNs) on fluorine-18 fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) can be hampered by the paucity of anatomical landmarks. In non-small cell lung cancer (NSCLC) patients referred for locoregional LN staging, we prospectively examined to what extent localisation of LNs at PET reading could be improved by visual correlation with computed tomography (CT), or by anatometabolic PET+CT fusion images. Fifty-six patients with potentially operable NSCLC underwent CT, PET and surgical staging. Prospective reading was performed for CT, PET without CT, PET+CT visual correlation and PET+CT fusion. Reading was blinded to surgical pathology data and noted on a standard LN map. Surgical staging was available for 493 LN stations. In the evaluation per individual LN station, CT was accurate in 87%, PET in 91% and visual correlation and fusion in 93%. In the identification of the nodal stage, CT was correct in 28/56 patients (50%), PET in 37/56 (66%), visual correlation in 40/56 (71%), and fusion in 41/56 (73%). It is concluded that in the exact localisation of metastatic thoracic LNs, the accuracy of reading of PET is increased if the PET images can be visually correlated with CT images. PET+CT anatometabolic fusion images add only a marginal benefit compared with visual correlation.