No abstract available.
Tomography, Emission-Computed, Single-Photon*

No abstract available.
Tomography, Emission-Computed, Single-Photon

No abstract available.
Tomography, Emission-Computed, Single-Photon*

No abstract available.
Tomography, Emission-Computed, Single-Photon*

No abstract available.
Tomography, Emission-Computed, Single-Photon*

No abstract available.
Tomography, Emission-Computed, Single-Photon*

No abstract available.
Perfusion* ; Tomography, Emission-Computed, Single-Photon*

PURPOSE: The pvrpose of this study was to evaluate the accuracy of radioactivity quantitation in Tc-99m SPECT by using combined scatter and attenuation correction. MATERIALS AND METHODS: A cylindrical phantom which simulates tumors (T) and normal tissue (B) was filled with varying activity ratios of Tc-99m. We acquired emission scans of the phantom using a three-headed SPECT system (Trionix, Inc.) witb two energy windows (photopeak window: 126 154 keV and scatter window: 101 123 keV). We performed the scatter correction with dual-energy window subtraction method (k=0.4) and Chang attenuation correction. Three sets of SPECT images were reconstructed using combined scatter and attenuation correction (SC+AC', attenuation correction (AC) and without any correction (NONE). We compared T/B ratio, irnage contrast [(T-B)/(T+B)) and absolute radioactivity with true values. RESULTS: SC+AC images had the highest mean values of T/B ratios. Image contrast was 0.92 in SC+AC, which was close to the true value of 1, and higher than AC (0.77) or NONE (0.80). Errors of true activity by SPECT images ranged from 1 to 11% for SC+AC, 22-47% for AC, and 2 16% for NONE in a phantom which was located 2.4cm from the phantom surface. In a phantom located 10,0cm from the surface, SC+AC underestimated by ?4%, NON.E 40%. However, AC overestimated by 10%. CONCLUSION: We conclude that accurate SPECT activity quantitation of Tc-99m distribution can be achieved by dual window scatter correc.tion combined with attenuation correction.
Radioactivity ; Tomography, Emission-Computed, Single-Photon*

No abstract available.
Brain* ; Schizophrenia ; Tomography, Emission-Computed, Single-Photon*

PURPOSE: We investigated reproducibility of the quantification of left ventricular volume and ejection fraction, and grading of myocardial wall motion and systolic thickening when we used gated myocardial SPECT and Cedars quantification software. MATERIALS AND METHODS: We performed gated myocardial SPECT in 33 consecutive patients twice in the same position after Tc-99m-MIBI SPECT. We used 16 frames per cycle for the gatingof sequential Tc-99m-MTBI SPECT. After reconstruction, we used Cedars quantitative gated SPECT and calculated ventricular volume and ejection fraction (EF), Wall motion was graded using 5 point score. Wall thickening was graded using 4 point score. Coefficient of variation for re-examination of volume and fraction were calculated. Kappa values (k-value) for assessing reproducibility of wall motion or wall thickening were calculated. RESULTS: Enddiastolic volumes (EDV) ranged from 58 mi to 248 ml (122 ml +/- 42 ml), endsystolic volumes (ESV) from 20 mi to 174 mi (65 ml +1- 39 ml), and EF from 20% to 68% (51% +/- 14%). Geometric mean of standard deviations of 33 patients was 5.0 ml for EDV, 3.9 ml for ESV and 1.9% for EF. Their average differences were not different from zero (p>0.05). k-value for wall motion using 2 consecutive images was 0.76 (confidence interval: 0.71-0.81). k-value was 0.87 (confidence interval:0.83-0.90) for assessment of wall thickening. CONCLUSION: We concluded that quantification of functional indices, assessment of wall motion and wall thickening using gated Tc-99m-MIBI SPECT was reproducible and we could use this method for the evaluation of short-acting drug effect.
Heart ; Humans ; Tomography, Emission-Computed, Single-Photon*