Comparative study of three different approaches on the estimation of the lung-heart ratio in thallium 201 scintigrams in relation to the extent of coronary artery disease and left ventricular function

Abstract

Uptake of thallium 201 (201Tl) in the lungs has been proposed as a measure of left ventricular dysfunction with exercise. To study this hypothesis, we compared the lung/-heart (LH) ratio assessed from anterior planar images (ANT-P), from anterior images obtained during single photon emission tomography (SPET) acquisition (ANT-T) and from short-axis tomographic cross-sections (CS) in early post-exercise thallium 201 scintigrams. The study population consisted of 54 prepercutaneous transluminal coronary angioplasty (PTCA) studies (82% with single-vessel disease), 50 post-PTCA studies, 33 pre-coronary artery bypass surgery (CABG) studies (71% with three-vessel disease), 30 post-CABG studies and 30 patients with a left ventricular dysfunction (LVD) due to an acute myocardial infarction; 18 individuals with a low likelihood of coronary artery disease (CAD) served as a control group. The results demonstrated that, on average, the LH ratios obtained from ANT-P and ANT-T were not significantly different for all study groups; these ratios increased significantly with ischaemia and with LVD relative to non-ischaemic situations. However, the LH ratios in CS did not show a relation with ischaemia nor with LVD and differed significantly from the LH-ratios assessed from the anterior approaches. Each of the three approaches (ANT-P, ANT-T, CS) was characterized by large overlaps of LH ratios for the different study groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships between the lung-heart ratio assessed from post-exercise thallium-201 myocardial tomograms, myocardial ischemia and the extent of coronary artery disease

“…Also no correlation was found between the average LH-ratio and the LVEF in rest. This observation is in agreement with the literature [24,25,28]. In our study population the average LH-ratio in the PRE-PTCA group was slightly higher than in the patients waiting for surgery.…”

“…T h e L H -r a t i o in these early studies was d e t e r m i n e d in a n t e r i o r planar images. L a t e r studies d e m o n s t r a t e d that assessm e n t of the L H -r a t i o in a n t e r i o r images o b t a i n e d during S P E C T was also feasible and r e p r o d u c i b l e , despite lower count densities in these images as compared to the planar studies [24,25,27]. Worldwide the use of planar techniques is declining in favor of tomographic imaging.…”

“…In recent studies the uptake of T1-201 in the lungs was determined in reconstructed short-axis slices of SPECT-studies. However, this method failed to identify patients with multivessel CAD [24]. Based on these negative results obtained from these reconstructed slices, we decided to further investigate the diagnostic value of the uptake of TI-201 in the lungs in the anterior view of SPECT acquisition studies, which are characterized by lower count densities as compared to the planar studies.…”

The use of thallium-201 lung/heart ratios

“…Mannting (1990) (Fig. Ilmer et al (1991) compared 3 different methods for the quantitation of lung-heart ratios. The lung uptake was measured on an image obtained by adding up 8 frames from the anterior to the 45 ° right anterior oblique projection.…”