Left ventricular ejection fraction calculated by SPECT and planar MUGA: A comparison of 100 cases

Abstract

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Objectives: Objectives: We sought to determine whether LVEF measured by planar and SPECT gated imaging were comparable.

Methods: Methods: One hundred consecutive patients (76 females and 24 males, mean age 54.8), who underwent both SPECT and planar MUGA between July and September 2004 were enrolled in this study. Each patient was studied sequentially using a dual detector gamma camera. From the best septal image, planar data were recorded in a 64 x 64 matrix, with ECG gating of 16 frames per cycle. 180 degree SPECT (16 frames/cycle, 64 azimuths, 20 seconds/azimuth, from right anterior oblique to left posterior oblique) was conducted immediately after planar acquisition. Planar LVEF was determined manually with 2 regions of interest over the left ventricular end- systolic and end-diastolic images respectively, and a background region taken adjacent to the left ventricular apex. For SPECT, LVEF was obtained using the automatic quantitative gated SPECT program provided by the manufacturer.

Results: Results: There was significant correlation between LVEF calculated from the planar and SPECT image sets. Pearson's correlation coefficient was r = 0.79 (figure 1). Best fitting line gave the equation SPECT = 1.025 * Planar, where the slope of 1.025 had a confidence interval of (0.868, 1.182). The intercept estimate of 0 had a confidence interval of (-1, 1). This suggests at most a bias of 1% in either direction if one uses Planar MUGA to estimate SPECT MUGA.

Conclusions: Conclusions: LVEF obtained by SPECT MUGA is comparable to the planar technique and can be a useful substitute, as SPECT additionally provides information on other cardiac chambers.