• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.94-100
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• 2011

Purpose: Basal/Acetazolamide-challenged brain perfusion SPECT is very useful to assess cerebral perfusion and vascular reserve. However, as there is a trade off between sensitivity and spatial resolution in the selection of collimator, the selection of optimal collimator is crucial. In this study, we examined three collimators to select optimal one for 1-day brain perfusion SPECT. Materials and Methods: Three collimators, low energy high resolution-parallel beam (LEHR-par), ultra resolution-fan beam (LEUR-fan) and super fine-fan beam (LESFR-fan), were tested for 1-day imaging using Triad XLT 9 (TRIONIX). The SPECT images of Hoffman 3D brain phantom filled with 99mTc of 170 MBq and a normal volunteer were acquired with a protocol of 50 kcts/frame and detector rotation of 3 degree. Filterd backprojection (FBP) reconstruction with Butterworth filter (cut off frequencies, 0.3 to 0.5) was performed. The quantitative and qualitative assessments for three collimators were performed. Results: The blind tests showed that LESFR-fan provided the best image quality for Hoffman brain phantom and the volunteer. However, images for all the collimator were evaluated as 'acceptable'. On the other hand, in order to meet the equivalent signal-to-noise ratio (SNR), total acquisition time or radioactivity dose for LESFR-fan must have been increased up to almost twice of that for LEUR-fan and LEHR-par. The volunteer test indicated that total acquisition time could be reduced approximately by 10 to 14 min in clinical practice using LEUR-fan and LEHR-par without significant loss on image quality, in comparison with LESFR-fan. Conclusion: Although LESFR-fan provides the best image quality, it requires significantly more acquisition time than LEUR-fan and LEHR-par to provide reasonable SNR. Since there is no significant clinical difference between three collimators, LEUR-fan and LEHR-par can be recommended as optimal collimators for 1-day brain perfusion imaging with respect to image quality and SNR.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.57-62
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• 2009

Purpose: Brain SPECT study is more sensitive to motion than other studies. Especially, when applying 1-day subtraction method for Diamox SPECT, it needs shorter study time in order to prevent reexamination. We were required to have new study condition and analysing method on dual detector system because triple head camera in Seoul National University Hospital is to be disposed. So we have tried to increase image quality and make the dual and triple head to have equivalent study time by using a new analysing program. Materials and Methods: Using IEC phantom, we estimated contrast, SNR and FWHM. In Hoffman 3D brain phantom which is similar with real brain, we were on the supposition that 5% of injected doses were distributed in brain tissue. To compare with existing FBP method, we used fan-beam collimator. And we applied 15 sec, 25 sec/frame for each SEPCT studies using LEHR and LEUHR. We used OSEM2D and Onco-flash3D reconstruction method and compared reconstruction methods between applied Gaussian post-filtering 5mm and not applied as well. Attenuation correction was applied by manual method. And we did Brain SPECT to patient injected 15 mCi of $^{99m}Tc$-HMPAO according to results of Phantom study. Lastly, technologist, MD, PhD estimated the results. Results: The study shows that reconstruction method by Flash3D is better than exiting FBP and OSEM2D when studied using IEC phantom. Flowing by estimation, when using Flash3D, both of 15 sec and 25 sec are needed postfiltering 5 mm. And 8 times are proper for subset 8 iteration in Flash3D. OSEM2D needs post-filtering. And it is proper that subset 4, iteration 8 times for 15sec and subset 8, iteration 12 times for 25sec. The study regarding to injected doses for a patient and study time, combination of input parameter-15 sec/frame, LEHR collimator, analysing program-Flash3D, subset 8, iteration 8times and Gaussian post-filtering 5mm is the most appropriate. On the other hands, it was not appropriate to apply LEUHR collimator to 1-day subtraction method of Diamox study because of lower sensitivity. Conclusions: We could prove that there was also an advantage of short study time effectiveness in Dual camera same as Triple gamma camera and get great result of alternation from existing fan-beam collimator to parallel collimator. In addition, resolution and contrast of new method was better than FBP method. And it could improve sensitivity and accuracy of image because lesser subjectivity was input than Metz filter of FBP. We expect better image quality and shorter study time of Brain SPECT on Dual detector system.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.99-103
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• 2011

Purpose: Head movement during brain perfusion SPECT (Diamox) scan is a one of important issues which decreases image quality. It also causes repeated scans. This study was designed to evaluate variable factors causing scan failures. Materials and Methods: 676 patients (359 men, 317 women, age average $54.5{\pm}18.4$) for brain perfusion SPECT (Diamox) scan from March, 2010 to Feb. 2011 were used as a subject. Age data and the kind of disease(Moyamoya disease (MMD), None moyamoya disease (NMMD), Cerebral infarction (CI)), test performance outcome (success,failure) were collected. The head movement factors(gender, disease, age, head fixation device) were evaluated by chi-square test and logistic regression analysis Results: The result showed that men had higher scan failure rate than women. Seniors in seventies(men 3.4%, women 1.5%) showed the most highest failure rate. Using head fixation device increased scan success rate up to 94.4~97.7%. The scan success rate is dependent upon gender, head fixation device by chi-square test(${\chi}^2$=3.8 (df=1, p<0.05), ${\chi}^2$=10.4 (df=1, p<0.001)) Gender, disease(CI), head fixation device showed very effective result in logistic regression analysis.(Wald=3.3 (p<0.07), Wald=3.7 (p<0.05), Wald=9.3 (p<0.05) Conclusion: It is demonstrated that gender, disease, using head fixation device is statistically very useful factors. Especially, head fixation device is a main key minimizing repeated scan.

• The Korean Journal of Nuclear Medicine
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• v.33 no.4
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• pp.352-361
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• 1999

Purpose: Carotid endarterectomy nay benefit patients with bilateral carotid stenosis by improving cerebro-vascular hemodynamics of ipsilateral as well as contralateral cerebral hemispheres. We investigated cerebro-vascular hemodynamics after carotid endarterectomy in patients with contralateral carotid occlusion by acetazolamide stress brain SPECT. Materials and Methods: Subjects were 14 symptomatic patients (all men, mean age 66 yrs) with carotid stenosis (>50%) with contralateral carotid occlusion. Acetazolamide stress Tc-99m ECD brain SPECTs were performed within 2 weeks before and after carotid endarterectomy using one day protocol. Cerebral blood flow (CBF) and cerebrovascular reserve (CVR) were assessed visually. In 12 patients, correlation between the patency of proximal anterior cerebral or anterior communicating arteries (A1/A-comm) and the improvement of CBF or CVR after endarterectomy was assessed. Results: Preoperative SPECT showed reduced CBF in 2 ipsilateral and 10 contralateral hemispheres. CVR was reduced in 4 ipsilateral and 9 contralateral hemispheres. Of 12 hemispheres with reduced CBF, 2 hemispheres (16.7%) showed improvement of CBF after endarterectomy. However, reduced CVR was improved in all 4 ipsilateral and 7 of 9 (78%) of contralateral hemispheres after endarterectomy. Three of4 with stenotic Al/A-comm and 4 of 8 with patent A1/A-comm had reduced contralateral CVR. Reduced contralateral CVR improved in all 3 patients with stenotic A1/A-comm and 3 of 4 with patent A1/A-comm. Conclusion: Acetazolamide stress brain SPECT demonstrated improvement of compromised cerebrovascular reserve in not only ipsilateral but also contralateral hemispheres of patients with contralateral carotid occlusion after carotid endarterectomy, and may, therefore, be useful for evaluating cerebral blood flow and cerebrovascular reserve after carotid endarterectomy.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.4
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• pp.280-286
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• 2009

Purpose: The aim of this study was to evaluate the hemodynamic changes after endovascular stenting in patients with unilateral middle cerebral artery (MCA) stenosis using statistical probabilistic anatomical mapping (SPAM) analysis of basal/acetazolamide (ACZ) Tc-99m ECD brain perfusion SPECT. Materials and Methods: Eight patients (3 men and 5 women, 64.8$\pm$10.5 years) who underwent endovascular stenting for unilateral MCA stenosis were enrolled. Basal/ACZ Tc-99m ECD brain perfusion SPECT studies were performed by one-day protocol before and after stenting. Using SPAM analysis, we compared basal cerebral perfusion (BCP) counts and cerebrovascular reserve (CVR) index of the MCA territory before stenting with those after stenting. Results: After stenting, no patient had any complication nor additional stroke. In SPAM analysis, 7 out of the 8 patients had improved BCP counts of the MCA territory and 7 out of the 8 patients had improved CVR index of the MCA territory after stenting. Before stenting, the mean BCP counts and CVR index in the affected MCA territory were 47.1$\pm$2.2 ml/min/100 g and -2.1$\pm$2.9%, respectively. After stenting, the mean BCP counts and CVR index in the affected MCA territory were improved significantly (48.3$\pm$2.9 ml/min/100 g, p =0.025 and 0.1$\pm$1.3%, p =0.036). Conclusion: This study revealed that SPAM analysis of basal/ACZ brain perfusion SPEG would be helpful to evaluate hemodynamic efficacy of endovascular stenting in unilateral MCA stenosis.