Differential sensitivity of radionuclide ventriculography for the detection of anterior and inferior infarction.

Abstract

SUMMARY Attenuation of counts from the more distant inferior portion of the left ventricular blood pool in equilibrium radionuclide ventriculography may mean that inferior infarction is less likely to be detected than anterior infarction. Fourier amplitude and phase images can be used to map the extent and timing of regional ventricular wall motion and this study assesses their use for the detection of anterior and inferior infarction. Normal regional values of amplitude and phase were established in 38 individuals without evidence of cardiac abnormality. In 20 patients with anterior infarcts, though the sensitivity of the combined left anterior oblique amplitude and phase images was high (95%) it was lower (77%) in 39 with inferior infarcts, principally because the sensitivity of the phase image for the detection of inferior infarcts was only 39%. Right anterior oblique images generated from a first pass study detected all 13 patients with inferior infarcts. The mean left ventricular ejection fraction was significantly lower in the patients with anterior infarcts (37%) than in those with inferior infarcts (48%). Although the mean wall motion score on x ray contrast ventriculography was slightly lower in the patients with anterior infarction, the high sensitivity of the right anterior oblique amplitude and phase images in inferior infarction suggests that attenuation of counts is an important cause of reduced sensitivity of the left anterior oblique images. This may also partly explain the lower ejection fractions in inferior infarction.It follows that both a right anterior oblique first pass study and a left anterior oblique equilibrium study are necessary for an accurate description of regional wall motion. images show motion of all parts of the left ventricle and they differ from methods that display contours; these only show motion of walls that are perpendicular to the plane of projection. Together, the images detect abnormal wall motion because abnormalities of both the extent and timing of contraction occur after myocardial infarction.45In the usual left anterior oblique projection, each left ventricular pixel represents a narrow column of blood passing from the anterior to the inferior wall. Changes in counts are the result of motion of both of the walls, and abnormal motion of either will lead to abnormalities of amplitude and phase. This may make it unclear which part of the ventricle is giving rise to an abnormality, but in practice the ambiguity can be resolved by the recognition of common pattems of wall motion. For instance, an amplitude defect in the centre of the left ventricle could represent either anterior or inferior hypokinesis, but 411

A survey of nuclear cardiological practice in Great Britain. The British Nuclear Cardiology Group.

“…Median camera age in Great Britain is 7 five years with some centres having 10 year old 7 6 cameras. Given the rapid advances in camera 2 and computer design this equipment is 2 relatively old, suggesting a low level of capital investment.…”

Improved assessment of inferior left ventricular wall motion using biplane equilibrium radionuclide ventriculography

“…Both of these studies, however, relied on subjective analysis and hence assessed only the two-dimensional motion of left ventricular boundaries. Underwood and colleagues [3] demonstrated improvement using right anterior oblique (RAO) amplitude and phase images generated from a first-pass study but this is technically more demanding than equilibrium imaging. Arrington and colleagues [4] used left posterior oblique (LPO) imaging assessing regional wall motion subjectively from the cine display.…”