[New approaches to quantifying early disorders and perfusion inhomogeneity of the myocardium according to the data of single-photon emission computed tomography].

OBJECTIVE

To develop novel quantitative approaches of myocardial perfusion analysis, to assess clinical usefulness of new parameters of initial myocardial perfusion impairments.

MATERIAL AND

METHODS

80 patients selected from our database formed four groups: 20 patients with no cardiac disease suspect, no ischemic heart disease (IHD) risk factors and definitely normal myocardial perfusion (group 1), 40 patients with equivocal perfusion patterns, that are usually described visually as “inhomogeneous”: 20 – with one subtle perfusion defect (group 2), 20 – with multiple ones (group 3), and 20 patients with non-severe but reliable defects, due to post-MI or another nontransmural cardiac event consequence. None of patients had current cardiac symptoms, positive stress-test results and/or single-photon emission computed tomography (SPECT) signs of stress-induced ischemia, so only rest images were analyzed. Perfusion maps were assessed quantitatively with Summed Rest Score (SRS) and Rest Extent (RE). Also new parameters ósev (severity sigma) и óhet (heterogeneity sigma) were used. They were calculated as mean-square deviations of relative perfusion values (in %) in each of 17 standard segments in reference to maximum of 100% (for ósev) and to arithmetical mean of those values (for óhet). To minimize known artifacts from CTACcorrected and noncorrected images, relative perfusion values for each segment were taken as maximal numbers of both images.

RESULTS

ósev in groups 1, 2, 3 and 4 was 15.9±2.6, 20.4±2.9, 22.4±3.4 and 26.0±3.9 (all paired p (s)<0.05, except p (group 2–3) = 0.19), óhet – 5.4±0.7, 9.1±1.6, 4.4±0.8, 11.3±2.1 (all paired p (s)<0.05 except p (group 1–3) = 0.11), respectively. Rest Extent in groups 1, 2, 3 and 4 was 4.1±1.7, 5.0±2.0, 4.7±2.3, 6.1±2.0 (all paired p (s)>0.05 except p (group 1–4) = 0.020); SRS – 1.3±0.6, 1.9±1.3, 1.6±1.4, 3.0±0.6 (all paired p (s)>0.05 except p (group 1–4)=0.013).

CONCLUSION

Parameters ósev and óhet are suitable for quantitative description of myocardial perfusion “inhomogeneity”, they are better than Extent/SRS in delineating normal/equivocal (inhomogeneous)/abnormal perfusion patterns.