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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Asia Oceania Journal of Nuclear Medicine and Biology
- نوع مقاله: Journal Article
- کلمات کلیدی: 18F-FDG ,99mTc-tetrofosmin,DEW method,PET / SPECT system
- چکیده:
- چکیده انگلیسی: Objective(s): Use of a positron emission tomography (PET)/single-photon
emission computed tomography (SPECT) system facilitates the simultaneous
acquisition of images with fluorine-18 fluorodeoxyglucose (18F-FDG) and
technetium (99mTc)-tetrofosmin. However, 18F has a short half-life, and 511
keV Compton-scattered photons are detected in the 99mTc energy window.
Therefore, in this study, we aimed to investigate the consequences of these
facts.
Methods: The crosstalk correction for images in the 99mTc energy window
involved the dual energy window (DEW) subtraction method. In phantom
studies, changes in the count of uniform parts in a phantom (due to attenuation
from decay), signal detectability in the hot-rod part of the phantom, and the
defect contrast ratio in a cardiac phantom were examined.
Results: For 18F-FDG in the step-and-shoot mode, nearly a 9% difference was
observed in the count of projection data between the start and end positions
of acquisition in the uniform part of the phantom. Based on the findings,
the detectability of 12 mm hot rods was relatively poor. In the continuous
acquisition mode, the count difference was corrected, and detectability of the
hot rods was improved. The crosstalk from 18F to the 99mTc energy window
was approximately 13%. In the cardiac phantom, the defect contrast in 99mTc
images from simultaneous dual-radionuclide acquisition was improved by
approximately 9% after DEW correction; the contrast after correction was
similar to acquisition with 99mTc alone.
Conclusion: Based on the findings, the continuous mode is useful for 18F-FDG
acquisition, and DEW crosstalk correction is necessary for 99mTc-tetrofosmin
imaging.- انتشار مقاله: 18-03-1394
- نویسندگان: Yasuyuki Takahashi,Mizuki Mochiki,Keiko Koyama,Toshihiko Ino,Hiroyuki Yamaji,Atsuko Kawakami
- مشاهده
- جایگاه : پژوهشی
- مجله: Asia Oceania Journal of Nuclear Medicine and Biology
- نوع مقاله: Journal Article
- کلمات کلیدی: standardized uptake value,time-of-flight,point-spread-function,18F-FDG , tumor size
- چکیده:
- چکیده انگلیسی: Objective(s): The present study was conducted to examine whether the standardized uptake value (SUV) may be affected by the spatial position of a lesion in the radial direction on positron emission tomography (PET) images, obtained via two methods based on time-of-flight (TOF) reconstruction and point spread function (PSF).
Methods: A cylinder phantom with the sphere (30mm diameter), located in the center was used in this study. Fluorine-18 fluorodeoxyglucose (18F-FDG) concentrations of 5.3 kBq/ml and 21.2 kBq/ml were used for the background in the cylinder phantom and the central sphere respectively. By the use of TOF and PSF, SUVmax and SUVmean were determined while moving the phantom in a horizontal direction (X direction) from the center of field of view (FOV: 0 mm) at 50, 100, 150 and 200 mm positions, respectively. Furthermore, we examined 41 patients (23 male, 18 female, mean age: 68±11.2 years) with lymph node tumors , who had undergone 18F-FDG PET examinations. The distance of each lymph node from FOV center was measured, based on the clinical images.
Results: As the distance of a lesion from the FOV center exceeded 100 mm, the value of SUVmax, which was obtained with the cylinder phantom, was overestimated, while SUVmean by TOF and/or PSF was underestimated. Based on the clinical examinations, the average volume of interest was 8.5 cm3. Concomitant use of PSF increased SUVmax and SUVmean by 27.9% and 2.8%, respectively. However, size of VOI and distance from the FOV center did not affect SUVmax or SUVmean in clinical examinations.
Conclusion: The reliability of SUV quantification by TOF and/or PSF decreased, when the tumor was located at a 100 mm distance (or farther) from the center of FOV. In clinical examinations, if the lymph node was located within 100 mm distance from the center of FOV, SUV remained stable within a constantly increasing range by use of both TOF and PSF. We conclude that, use of both TOF and PSF may be helpful.
- انتشار مقاله: 02-04-1394
- نویسندگان: Yasuharu Wakabayashi,Kenichi Kashikura,Yasuyuki Takahashi,Hitoshi Yabe,Akihiro Ichikawa,Souichi Yamamoto,Ayumi Ishii,Kunio Doi
- مشاهده
- جایگاه : پژوهشی
- مجله: Asia Oceania Journal of Nuclear Medicine and Biology
- نوع مقاله: Journal Article
- کلمات کلیدی: Semiconductor detector,Energy resolution,Dual radioisotopes simultaneous SPECT,123I-BMIPP
- چکیده:
- چکیده انگلیسی: Objective(s): The energy resolution of a cadmium-zinc-telluride (CZT) solid-state semiconductor detector is about 5%, and is superior to the resolution of the conventional Anger type detector which is 10%. Also, the window width of the high-energy part and of the low-energy part of a photo peak window can be changed separately. In this study, we used a semiconductor detector and examined the effects of changing energy window widths for 99mTc and 123 I simultaneous SPECT.
Methods: The energy “centerline” for 99mTc was set at 140.5 keV and that for 123I at 159.0 keV. For 99mTc, the “low-energy-window width” was set to values that varied from 3% to 10% of 140.5 keV and the “high-energy-window width” were independently set to values that varied from 3% to 6% of 140.5 keV. For 123I, the “low energy-window-width” varied from 3% to 6% of 159.0 keV and the high-energy-window width from 3% to 10% of 159 keV. In this study we imaged the cardiac phantom, using single or dual radionuclide, changing energy window width, and comparing SPECT counts as well as crosstalk ratio.
Results: The contamination to the 123I window from 99mTc (the crosstalk) was only 1% or less with cutoffs of 4% at lower part and 6% at upper part of 159KeV. On the other hand, the crosstalk from 123I photons into the 99mTc window mostly exceeded 20%. Therefore, in order to suppress the rate of contamination to 20% or less, 99mTc window cutoffs were set at 3% in upper part and 7% at lower part of 140.5 KeV. The semiconductor detector improves separation accuracy of the acquisition inherently at dual radionuclide imaging. In, this phantom study we simulated dual radionuclide simultaneous SPECT by 99mTc-tetrofosmin
and 123 I-BMIPP.
Conclusion: We suggest that dual radionuclide simultaneous SPECT of 99mTc and 123I using a CZT semiconductor detector is possible employing the recommended windows.- انتشار مقاله: 27-01-1393
- نویسندگان: Yasuyuki Takahashi,Masao Miyagawa,Yoshiko Nishiyama,Naoto Kawaguchi,Hayato Ishimura,Teruhito Mochizuki
- مشاهده