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[Assessment of left ventricular function by gated cardiac blood-pool emission computed tomography using a rotating
M Narita1, T Kurihara, K Murano
1Department of Internal Medicine, Sumitomo Hospital.
Insights
Gated cardiac blood-pool SPECT using Tc-99m effectively evaluates left ventricular (LV) global and regional functions. This nuclear imaging technique shows strong correlation with contrast ventriculography for LV volumes and wall motion analysis.
Area of Science:
- Nuclear Medicine
- Cardiovascular Imaging
- Diagnostic Radiology
Background:
- Left ventricular (LV) function assessment is crucial in coronary artery disease.
- Traditional methods may have limitations in evaluating both global and regional LV function accurately.
Purpose of the Study:
- To determine the clinical utility of gated cardiac blood-pool single photon emission computed tomography (SPECT) with Tc-99m for assessing LV global and regional functions.
- To compare the accuracy of SPECT with contrast ventriculography and planar imaging for LV function evaluation.
Main Methods:
- 18 patients with coronary artery disease underwent gated cardiac blood-pool SPECT with Tc-99m.
- LV volumes were calculated using voxel integration and determined cut-off levels derived from phantom studies.
- LV global and regional functions were assessed and compared with contrast ventriculography and planar imaging.
Main Results:
- SPECT-derived LV end-diastolic volume, end-systolic volume, and ejection fraction showed excellent correlation with contrast ventriculography (r=0.89-0.94).
- Wall motion analysis using SPECT demonstrated superior correlation (r=0.84) compared to planar imaging (r=0.62) versus ventriculography.
- SPECT provided more accurate regional wall motion analysis, particularly in septal and infero-posterior segments.
Conclusions:
- Gated cardiac blood-pool SPECT with Tc-99m is a valuable tool for evaluating both global and regional left ventricular function in patients with coronary artery disease.
- Despite longer acquisition times, SPECT offers improved accuracy for regional wall motion assessment compared to planar imaging.
Abstract:
To elucidate the usefulness of gated cardiac blood-pool single photon emission CT (SPECT) with Tc-99m for the evaluation of left ventricular (LV) global and regional functions, 18 patients with coronary artery disease were studied. Thirty-two gated projection images were obtained over 360-degree at 16 frames per cardiac cycle. As LV volume was calculated by integrating the numbers of voxels which constituted LV and multiplying by the volume of a single voxel (0.1143 ml), we performed phantom studies to determine the appropriate cut-off level to detect LV outline. These cut-off levels were affected by the background activity and organ volume itself. So we constructed Volume-Cut-Level-Curve at each background activity. In clinical studies, short axis images which constituted LV were selected and provisional LV volumes were calculated at the cut-off levels of 45, 50 and 55%. These volumes were plotted on the Volume-Cut-Level-Curve and the true cut-off levels were obtained to calculate LV end-diastolic or end-systolic volume (EDV, ESV). The cut-off levels were different at every patient and ED or ES. EDV, ESV and LV ejection fraction obtained by SPECT were correlated well with those obtained by contrast ventriculography (LVG) (r = 0.89, 0.94, 0.94 each, p less than 0.01). For the LV wall motion analysis, LVGs obtained at two projections were compared with SPECT or gated cardiac blood-pool planar imaging (Planar) in 5 segments. In addition to visual comparison, wall motion scores (WMS) based on the degree of wall motion abnormality were calculated in each segment. Correlation of WMS between LVG and SPECT (r = 0.84) was significantly (p less than 0.01) superior to that between LVG and Planar (r = 0.62). Especially in SPECT, wall motion analyses at septal and infero-posterior segments were superior to those in Planar. Although gated SPECT requires relatively long time to perform, it is a useful method to detect LV global and regional functions.