The capability of computed tomographic scanning to provide measurements of left ventricular mass in vivo was explored and compared with postmortem values. The study group comprised 22 dogs weighing between 9 and 28 kg and included 5 dogs with left ventricular hypertrophy. Serial nongated computed tomographic scans from the cardiac apex to base were obtained during steady state infusion of contrast medium. The total number of picture elements (pixels) representing the left ventricular myocardium on each 1 cm thick computed tomographic scan was determined in two ways: with a computer technique and with a manual tracing method. Left ventricular mass was calculated as the product of total myocardial volume (determined by pixels) and the specific gravity of canine myocardium. The results obtained with both computed tomographic methods correlated with the left ventricular mass measured at autopsy (computer method, correlation coefficient [r] = 0.95; standard error of the estimate [SEE] = 8.10 g and for the tracing method, r = 0.95; SEE = 8.38 g). These in vivo measurements were reproducible and appeared not to be significantly affected by left ventricular hypertrophy. The effect of cardiac motion on the measurements was assessed by rescanning eight animals at postmortem examination with the heart in situ. These results showed a modest (twofold) increase due to motion in the standard error of the estimate over the computed tomographic value at autopsy. Artifact due to adjacent lung tissue with low density is known to be a source of error in computed tomographic measurements. This was examined by scanning the excised hearts in a water phantom and was found not to significantly influence the results. This feasibility study represents a logical step in the application and validation of computed tomography in diagnosing heart disease. The extrapolation of these results to human subjects must be made cautiously, but there appear to be no major technical reasons why this use of computed tomography cannot be optimistically pursued.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine