Characteristics of single- and dual-photopeak energy window acquisitions with thallium-201 IQ-SPECT/CT system

13301甲第4651号博士（医学）金沢大学博士論文本文Full 以下に掲載：Annals of Nuclear Medicine 31(7) pp.529-535 2017. Springer. 共著者：Takayuki Shibutani, Masahisa Onoguchi, Hiroto Yoneyama, Takahiro Konishi, Shinro Matsuo, Kenichi Nakajima, Seigo Kinuy

Performance evaluation of fifth-generation ultra-high-resolution SPECT system with two stationary detectors and multi-pinhole imaging

Background Small-animal single-photon emission computed tomography (SPECT) systems with multi-pinhole collimation and large stationary detectors have advantages compared to systems with moving small detectors. These systems benefit from less labour-intensive maintenance and quality control as fewer prone parts are moving, higher accuracy for focused scans and maintaining high resolution with increased sensitivity due to focused pinholes on the field of view. This study aims to investigate the performance of a novel ultra-high-resolution scanner with two-detector configuration (U-SPECT5-E) and to compare its image quality to a conventional micro-SPECT system with three stationary detectors (U-SPECT+). Methods The new U-SPECT5-E with two stationary detectors was used for acquiring data with Tc-99m-filled point source, hot-rod and uniformity phantoms to analyse sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR). Three dedicated multi-pinhole mouse collimators with 75 pinholes each and 0.25-, 0.60- and 1.00-mm pinholes for extra ultra-high resolution (XUHR-M), general-purpose (GP-M) and ultra-high sensitivity (UHS-M) imaging were examined. For CNR analysis, four different activity ranges representing low- and high-count settings were investigated for all three collimators. The experiments for the performance assessment were repeated with the same GP-M collimator in the three-detector U-SPECT+ for comparison. Results Peak sensitivity was 237 cps/MBq (XUHR-M), 847 cps/MBq (GP-M), 2054 cps/MBq (UHS-M) for U-SPECT5-E and 1710 cps/MBq (GP-M) for U-SPECT+. In the visually analysed sections of the reconstructed mini Derenzo phantoms, rods as small as 0.35 mm (XUHR-M), 0.50 mm (GP-M) for the two-detector as well as the three-detector SPECT and 0.75 mm (UHS-M) were resolved. Uniformity for maximum resolution recorded 40.7% (XUHR-M), 29.1% (GP-M, U-SPECT5-E), 16.3% (GP-M, U-SPECT+) and 23.0% (UHS-M), respectively. UHS-M reached highest CNR values for low-count images; for rods smaller than 0.45 mm, acceptable CNR was only achieved by XUHR-M. GP-M was superior for imaging rods sized from 0.60 to 1.50 mm for intermediate activity concentrations. U-SPECT5-E and U-SPECT+ both provided comparable CNR. Conclusions While uniformity and sensitivity are negatively affected by the absence of a third detector, the investigated U-SPECT5-E system with two stationary detectors delivers excellent spatial resolution and CNR comparable to the performance of an established three-detector-setup

Serial examination of cardiac function and perfusion in growing rats using SPECT/CT for small animals

金沢大学疾患モデル総合研究センターFew studies have evaluated myocardial perfusion and ventricular function in normal, growing rats. We, therefore, evaluated serial changes in cardiac perfusion and function during the growth of normal rats using single photon emission computed tomography (SPECT) with technetium (99mTc)-sestamibi. Gated SPECT was serially performed in six normal rats. The left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) were calculated with Quantitative Gated SPECT software. The perfusion distribution was calculated as the percentage uptake of each of the 17 segments using Quantitative Perfusion SPECT software. As expected, the body weight (BW) of the rats increased with growth, but their heart rates (HR) did not change over time. EF decreased very slowly over time and showed a negative correlation with BW. EDV, ESV and SV showed strong positive correlations with BW. There were no significant differences in the percentage segmental uptake in 13 of the 17 segments during growth, except for three basal and one apical segments. Therefore, a single normal database could be applied for the evaluation of perfusion abnormalities in rats of at least 8 to 28 weeks old. © 2020, The Author(s)

An investigation into carbon structures in iron-loaded charcoal based on the Raman shift and line-shape of the G´-band

Abstract Charcoal samples prepared from wood impregnated with Fe3+ were characterized using Raman spectroscopy to investigate ordered structures consisting of sp2-carbon atoms. The iron-loaded charcoal samples were synthesized at relatively low temperatures (600–850 °C). Most of the Raman peak-tops of G´-bands observed in the charcoal were positioned in the narrow range of 2700–2690 cm−1; however, the G´-band positions of the charcoal synthesized in a carbonization-temperature (CT) range (650–750 °C) varied widely with measurement points and some of them displayed wavenumber values lower than 2690 cm−1. The G´-band positions were also affected by holding time at CT. None of the G´-bands observed in the iron-loaded charcoal exhibited positive asymmetrical line-shapes, unlike graphite. We proposed the ordered structures of sp2-carbon atoms in the iron-loaded charcoal based on the Raman spectral features of the G´-bands

小動物SPECT・PET同時測定法における物理現象の解明と定量評価法の確立

金沢大学医薬保健研究域保健学系小動物研究の中で虚血性心疾患の評価に重要な心筋バイアビリティは，別時相で収集されるため，小動物の時相差に伴う生理状態の違いが定量誤差となり，病態と分子情報のミスマッチが生じていた。その問題を解決するために，本研究ではTc-99m心筋血流とF-18の心筋糖代謝情報を対象に本邦初導入された小動物用SPECT・PET同時収集システムを用いて複数分子同時収集における心筋バイアビリティ定量評価法を開発した。小動物を模擬したファントムを新たに開発し，複数分子同時収集で問題となるクロストークによる画質劣化と部分容積効果による定量値の過小評価を改善するための補正技術を確立させた。Myocardial viability evaluation which is important for ischemic heart disease in small animal studies is acquired in different time phases, and it was a mismatch between the pathological condition and the molecular information due to the quantitative error caused by the difference in physiological state caused by the time phase difference of small animals. To resolve this problem, we developed a quantitative evaluation method of myocardial viability in simultaneous acquisition of multiple molecules for Tc-99m myocardial blood flow and F-18 myocardial glucose metabolism using the small animal SPECT/PET simultaneous acquisition system introduced for the first time in Japan.A phantom simulating a small animal was newly developed, and a correction technique was established to improve image quality due to crosstalk and underestimation of quantitative values caused by partial volume effect which are problems in simultaneous acquisition of multiple molecules.研究課題/領域番号:18K15628, 研究期間(年度):2018-04-01 - 2021-03-31出典：「小動物SPECT・PET同時測定法における物理現象の解明と定量評価法の確立」研究成果報告書　課題番号18K15628（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-18K15628/18K15628seika/ ）を加工して作

An Exploratory Study of Washout Rate Analysis for Thallium-201 Single-Photon Emission Computed Tomography Myocardial Perfusion Imaging Using Cadmium Zinc Telluride Detectors

The aim of this study was to assess the washout rate (WOR) for thallium-201-chloride single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) using cadmium zinc telluride detectors for SPECT (CZT SPECT) versus conventional Anger-type SPECT (conventional SPECT). A total of 52 Japanese patients were examined using CZT SPECT and conventional SPECT, and the global WORs were compared. Additionally, the MPI WORs were compared for patients with a normal MPI versus those in whom MPI reflected the patients’ multivessel disease (MVD) MPI. Washout rates were similar when approximated by CZT SPECT versus conventional SPECT 12.59 ± 2.26%/h vs 12.57 ± 2.27%/h ( P = .997), respectively. The WOR values for CZT SPECT versus conventional SPECT were 13.42%/h (1.53%/h) vs 13.93%/h (1.24%/h) ( P = .337), respectively, for 7 normal MPI patients, and 10.64 ± 2.20%/h vs 10.84 ± 2.26%/h ( P = .848), respectively, for 7 MVD-MPI patients. The WOR values for normal MPI versus MVD-MPI patients for CZT SPECT were 13.42 ± 1.53%/h vs 10.64 ± 2.20%/h ( P = .025), respectively. Thallium-201-chloride WOR values obtained with high-efficiency CZT SPECT, which enabled significantly reduced imaging times and use of a low-dose protocol, were similar to those obtained with conventional SPECT