Assessment of left ventricular diastolic filling: comparison of fixed and varying region of interest approaches.

Abnormalities in scintigraphic measurements of diastolic filling were assessed with respect to detection, reproducibility and sensitivity by means of fixed and varying left ventricular region-of-interest (ROI) approaches. Equilibrium blood pool scintigraphy was carried out in 11 control subjects, 15 patients with coronary artery disease (CAD), and 13 patients with hypertension. Results of these studies were analyzed for ejection fraction (EF), peak filling rate (PFR), time to PFR (TPFR), and filling fraction in the first third of diastole corrected for cycle length (FF1/3). With the fixed ROI technique, patients with CAD differed from the control subjects because they had lower EF (p less than 0.05), PFR (p less than 0.001), and FF1/3 (p less than 0.05) levels; patients with hypertension showed only a reduced FF1/3 (p less than 0.01). When the varying ROI method was employed, patients with CAD differed from normal subjects in their PFR (p less than 0.05) results; patients with hypertension and normal subjects differed in their FF1/3 (p less than 0.001) results. Although the ability to discriminate between patients and normal subjects was similar with the two techniques, interobserver variability was smaller and single observer reproducibility was greater with the fixed ROI method. We conclude that the fixed and varying ROI techniques are comparable in detecting diastolic filling abnormalities but that the fixed ROI method is superior in reducing measurement variability and may be the preferable method for analyzing serial studies and the response to therapeutic interventions.