No abstract

A non-uniform attenuation correction is necessary for the myocardial perfusion image (MPI) SPECT that is one of the images of the trunk. Simultaneous non-uniform attenuation correction during the process of SPECT reconstruction was enabled by developing hybrid SPECT/CT. Image acquisition of 99m Tc MPI with hybrid SPECT/CT was performed in a phantom study and clinical cases We evaluated the effect of non-uniform attenuation correction by Filtered Back Projection (FBP) or Ordered Subsets-Expectation Maximization (OS-EM) using visual analysis and quantitative analysis with a 17-segment model. The phantom study and the clinical cases differed somewhat as follows In the phantom study, the count increased significantly with non-uniform attenuation correction in visual analysis and quantitative analysis. In the clinical cases, non-uniform attenuation correction increased the quantitative count in the basal and middle layer of the heart, and visual uniformity of the whole heart improved. However, the visual and quantitative count in the apex decreased with non-uniform attenuation correction. As a result, diagnostic performance for coronary heart disease is expected to be improved by this new technique using hybrid SPECT/CT.

No abstract

In pediatric cases requiring quantification of cerebral blood flow (CBF) using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP) single-photon emission computed tomography (SPECT), arterial blood sampling is sometimes impossible due to issues such as movement, crying, or body motion. If arterial blood sampling fails, quantitative diagnostic assessment becomes impossible despite radiation exposure. We devised a new easy non-invasive microsphere (e-NIMS) method using whole-body scan data. This method can be used in conjunction with autoradiography (ARG) and can provide supportive data for invasive CBF quantification. In this study, we examined the usefulness of e-NIMS for pediatric cerebral perfusion semi-quantitative SPECT and compared it with the invasive ARG. The e-NIMS estimates cardiac output (CO) using whole-body acquisition data after 123I-IMP injection and the body surface area from calculation formula. A whole-body scan was performed 5 minutes after the 123I-IMP injection and CO was estimated by region of interest (ROI) counts measured for the whole body, lungs, and brain using the whole-body anterior image. The mean CBF (mCBF) was compared with that acquired via ARG in 115 pediatric patients with suspected cerebrovascular disorders (age 0–15 years). Although the mCBF estimated by the e-NIMS indicated a slight deviation in the extremely low- or high-mCBF cases when compared with the values acquired using the invasive ARG, there was a good correlation between the two methods (r = 0.799; p < 0.001). There were no significant differences in the mCBF values based on physical features, such as patients’ height, weight, and age. Our findings suggest that 123I-IMP brain perfusion SPECT with e-NIMS is the simplest semi-quantitative method that can provide supportive data for invasive CBF quantification. This method may be useful, especially in pediatric brain perfusion SPECT, when blood sampling or identifying pulmonary arteries for CO estimation using the graph plot method is difficult.

Background To demonstrate the association between pediatric outcomes and tracer hepatic uptake as a marker of systemic circulation in lymphoscintigraphy. Methods We included 31 initial lymphoscintigraphic studies. We compared the presence or absence of hepatic uptake between deceased and survived patients in both early and delayed images using Fisher's exact test. Kaplan–Meier survival analysis was performed based on imaging results, and these curves were compared using the log‐rank test. The primary endpoint was death and the survival period was defined from the day of examination to the day of the last visit or death. Results Of 31 patients, six died. Hepatic uptake was significantly different in both early and delayed images (early images, died [with/without visualization] vs. survived [with/without visualization], 0/6 vs. 13/12, P = 0.028; delayed images, died [with/without visualization] vs. survived [with/without visualization], 2/4 vs. 22/3, P = 0.014) between deceased and survived patients. Survival periods were significantly different between the two groups with and without hepatic uptake in early and delayed images (with/without visualization in early imags = 1,177.1 ± 773.8 days/426.7 ± 419.8 days, P = 0.008 and with/without visualization in delayed images = 821.3 ± 738.0 days/467.4 ± 452.4 days, P = 0.003). Conclusions Visualization of hepatic uptake in both early and delayed lymphoscintigraphy is associated with patient outcomes. Hepatic uptake could represent tracer inflow into the systemic circulation, indicating preservation of the connection between the lymphatic system and the systemic circulation. Physicians should evaluate these findings carefully on lymphoscintigraphy.