New functional polar maps for estimating regional cardiac function using ECG-gated technetium-99m-tetrofosmin SPECT

金沢大学大学院医学系研究科Objective: The purpose of this work was to develop functional parameters to analyze regional cardiac function using ECG-gated 99mTc-tetrofosmin SPECT. Our goal was to develop a methodology that used slice thickness correction, the generation of a time-activity curve and a polar map. Methods: Fourteen normal patients without evidence of coronary artery disease were studied. One hour after intravenous injection of 740-1110 MBq (20-30 mCi) 99mTc-tetrofosmin, ECG-gated SPECT data were acquired by dividing a cardiac cycle into 12 frames. The SPECT data were reconstructed from 11 of 12 frames into 3 views. The reconstruction of these images was repeated after performing slice thickness correction. Excluding the effect of different apex-to-base lengths at any frame during a cardiac cycle, 10 short-axis images with the same slice thickness were obtained. Each short-axis image was divided by 40 radii into 40 segments. The time-activity curve was generated from the total counts included in each segment plus both neighboring segments. Subsequently the curve fitting was performed using the second Fourier function. Results: From fitted curves and their differentials, we calculated end-systolic count, end-diastolic count, percent count increase, uptake, peak contraction rate, peak distention rate and contraction time. Conclusion: The functional polar maps visually demonstrated regional myocardial function. This method is expected to be helpful for assessing regional cardiac function using 99mTc-tetrofosmin

ラットを用いたジピリダモール負荷プラナー画像における 99mTc-tetrofosmin 摂取率: 摘出臓器の摂取率との比較

We studied how precisely images reflect tracer uptake .in the myocardium, and examined what degree technetium-99m-tetrofosmin (c-tetrofosmin) in the liver and gastrointestine gave the effect to a myocardial image. After administering dipyridamole and 99m Tc­ tetrofosmin to normal rats, we compared the myocardial uptakes obtained using a gamma camera with the actual uptakes in the excised organs. Methods : Thirty-seven rats were used. Following imaging the anterior view at 5, 10, 15, 30, 60 and 90 min after admini­ stration of the tracer, uptakes in the heart, lung, liver and blood were estimated with a well-type scintillation counter (WC) and represented as percentage of the injected dose per gram of tissue (%ID/g). The regions of interest (ROis) were placed on planar images (PI) and the uptake in each organ was estimated as percentage of the injected dose per pixel (%ID/pixel). The ratios of PI-to-WC and heart-to-organ were also evaluated. Results : Cardiac uptake with WC was 1.688%± 0.395% at 10 min post-injection. On the other hand, that with PI was 1.855%±0.965% at 10 min post-injection. There were particularly great differences from 15 min post-injection between both measurements (PI/WC ratio : about 1.2 times). Pulmonary uptake with WC was the maximum at 15 min (0.861%± 0.387%) post-injection, and there was. hardly a variation in the activity later than 15 min. However, PI measurement showed the maximum value at 15 min (0.777%±0.163%), and decreased gradually. Hepatic uptake with WC was the maximum at 5 min (1.545%±0.563 %), and rapidly decreased. On the other hand, PI measurement showed higher value than WC as" the whole. Conclusion : Pl measurement showed higher uptakes in each organ than WC measurement. There were great differences between both measurements, at late phase particularly. As one of these causes, it was considered that the decrease of activity in blood was different from that in each organ with increasing time

New functional polar maps for estimating regional cardiac function using ECG-gated technetium-99m-tetrofosmin SPECT

金沢大学大学院医学系研究科量子医療技術学Objective: The purpose of this work was to develop functional parameters to analyze regional cardiac function using ECG-gated 99mTc-tetrofosmin SPECT. Our goal was to develop a methodology that used slice thickness correction, the generation of a time-activity curve and a polar map. Methods: Fourteen normal patients without evidence of coronary artery disease were studied. One hour after intravenous injection of 740-1110 MBq (20-30 mCi) 99mTc-tetrofosmin, ECG-gated SPECT data were acquired by dividing a cardiac cycle into 12 frames. The SPECT data were reconstructed from 11 of 12 frames into 3 views. The reconstruction of these images was repeated after performing slice thickness correction. Excluding the effect of different apex-to-base lengths at any frame during a cardiac cycle, 10 short-axis images with the same slice thickness were obtained. Each short-axis image was divided by 40 radii into 40 segments. The time-activity curve was generated from the total counts included in each segment plus both neighboring segments. Subsequently the curve fitting was performed using the second Fourier function. Results: From fitted curves and their differentials, we calculated end-systolic count, end-diastolic count, percent count increase, uptake, peak contraction rate, peak distention rate and contraction time. Conclusion: The functional polar maps visually demonstrated regional myocardial function. This method is expected to be helpful for assessing regional cardiac function using 99mTc-tetrofosmin