[Clinical evaluation of Tl-201 ECG-gated myocardial SPECT--measurement of the wall systolic thickening rate].

Using Tl-201 ECG-gated myocardial SPECT, we estimated local systolic thickening of the left ventricular wall as Wall Systolic Thickening Rate (WSTR). Materials were 30 cases of 5 normals, 16 old myocardial infarctions (OMIs), 6 HCMs and 3 DCMs. The patients were injected with 111-185 MBq (3-5 mCi) of Tl-201 at rest. The projection data were acquired through 180 degrees in 24 directions, each of which consisted of 80-100 beats. The fundamental phantom study with thickness of 4, 8, 12, 16, 20 and 24 mm revealed that if radionuclide concentration and acquisition time were under the same condition, pixel counts correlated well with thickness of phantom. Therefore, pixel counts could be substituted for the relative ED and ES wall thickness. The Wall Systolic Thickening Rate was calculated as WSTR = [(ES-ED pixel counts) X 100/ED pixel counts (%)] with 5 points circumferential profile technique of both ED and ES short axial images from apex to base. Functional images of the WSTR were displayed with Bull's eye method and typical patterns were demonstrated. Mean values of the mean WSTR (mWSTR) in the ROIs in each group were as follows; In normals, mWSTR was 53.1 +/- 4.5% (mean +/- 1SD). In non-transmural OMIs, mWSTR was greater (33.0 +/- 8.1%) than that in transmural OMIs (14.0 +/- 4.5%) (p less than 0.01). In HCMs with non-uniform wall thickness, mWSTR in relatively non-hypertrophied area was greater (52.9 +/- 12.3%) than that in hypertrophied area (21.7 +/- 6.4%) (p less than 0.01). In DCMs, mWSTR was 18.5 +/- 1.9%.(ABSTRACT TRUNCATED AT 250 WORDS)