• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.322-323
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• 2002

Partial volume averaging effect of PET data influences on the accuracy of quantitative measurements of regional brain metabolism because spatial resolution of PET is limited. The purpose of this study was to evaluate the accuracy of partial volume correction carried out on $^{18}$ F-PET images using Hoffman brain phantom. $^{18}$ F-PET Hoffman phantom images were co-registered to MR slices of the same phantom. All the MR slices of the phantom were then segmented to be binary images. Each of these binary images was convolved in 2 dimensions with the spatial resolution of the PET. The original PET images were then divided by the smoothed binary images in slice-by-slice, voxel-by-voxel basis resulting in larger PET image volume in size. This enlarged partial volume corrected PET image volume was multiplied by original binary image volume to exclude extracortical region. The evaluation of partial volume corrected PET image volume was performed by region of interests (ROI) analysis applying ROIs, which were drawn on cortical regions of the original MR image slices, to corrected and original PET image volume. From the ROI analysis, range of regional mean values increases of partial volume corrected PET images was 4 to 14%, and average increase for all the ROIs was about 10% in this phantom study. Hoffman brain phantom study was useful for the objective evaluation of the partial volume correction method. This MR-based correction method would be applicable to patients in the. quantitative analysis of FDG-PET studies.

• Journal of radiological science and technology
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• v.45 no.3
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• pp.241-248
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• 2022

In this study, a recovery coefficient (RC) calculation was conducted that can correct the underestimation of the standardized uptake value (SUV) due to the partial volume effect (PVE) through phantom measurements and formulas. The experiment was conducted using a dynamic phantom capable of implement cranio-caudal movement at a respiratory rate of 15 times per minute along with the measured phantom experiment of the stopped state, and the RC of the moving state is calculated and compared. Ingenuity TF (Philips Healthcare, Netherland) was used as a positron emission tomography/computed tomography (PET/CT) device. PET-CT Phantom (Biodex Medical System, USA) was used as a phantom for measurement. A phantom image in a stationary state was acquired, and a moving phantom image was acquired using the AZ-733V Respiratory Phantom (Anzai Medical Co, Japan) capable of breathing movement in the cranio-caudal direction under the same acquisition parameters. For RC calculation, the sphere maximum radioactivity concentration and the background mean radioactivity concentration of the acquired images were measured, and the initially determined sphere and background radioactivity concentrations were calculated. The calculated RC was 0.08 to 0.72. The size of sphere smaller, it was confirmed that the RC reduced. And the RC in the moving state reduced than in the stationary state. As a result of this study, the change of the RC was confirmed according to the size of spheres and the phantom moving. Using the RC derived by implement movement of breathing with the respiratory phantom, it is possible to considering correction of underestimated SUV by the partial volume effect of PET images and the patient movements.

• Progress in Medical Physics
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• v.14 no.3
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• pp.203-210
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• 2003

PET (positron emission tomography) permits the investigation of physiological and biochemical processes in vivo. The accuracy of quantifying PET data is affected by its finite spatial resolution, which causes partial volume effects. In this study, we developed a method for partial volume correction using Hoffman phantom PET and MR data, and applied various FWHM (full width at half maximum) levels. We also applied this method to PET images of normal controls and tested for the possibility of clinical application. $^{18}$ F-PET Hoffman phantom images were co-registered to MR slices. The gray matter and white matter regions were then segmented into binary images. Each binary image was convolved by 4, 8, 12, 16 mm FWHM levels. These convolved images of gray and white matter were merged corresponding to the same level of FWHM. The original PET images were then divided by the convolved binary images voxel-by-voxel. These corrected PET images were multiplied by binary images. The corrected PET images were evaluated by analyzing regions of interests, which were drawn on the gray and white matter regions of the original MR image slices. We calculated the ratio of white to gray matter. We also applied this method to the PET images of normal controls. On analyzing the corrected PET images of Hoffman phantom, the ratios of the corrected images increased more than that of the uncorrected images. With the normal controls, the ratio of the corrected images increased more than that of the uncorrected images. The ratio increase of the corrected PET images was lower than that of the corrected phantom PET images. In conclusion, the method developed for partial volume correction in PET data may be clinically applied, although further study may be required for optimal correction.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.10-16
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• 2011

Purpose: The partial volume effect occurs because of limit of the spatial resolution. It makes partial loss of intensity and causes SUV to be lower than it should actually be. So the purpose of this study is to calculate recovery coefficient for correcting PVE from phantom study and to compare before and after SUV correction applying to PET/CT examination. Materials and Methods: The flangeless Esser PET phantom consisting of four hot cylinders was used for this study. All of the hot cylinders were filled with FDG solution of 20.72 MBq per 1000 ml, and the phantom background was filled with FDG solution of different concentrations (33.30, 22.20, 16.65 MBq per 6440 ml) to yield H/B ratios of around 4:1, 6:1 and 8:1. Using the Biograph Truepoint 40(SIEMENS, Germany), we applied recovery coefficient method to 30 patients who were diagnosed with lung cancer after PET/CT exam. And then we analyzed and compared SUV before and after correcting partial volume effect. Results: The smaller the diameter of hot cylinder becomes, the more recovery coefficient decreased. When we applied recovery coefficient to clinical patients and compared SUV before and after correcting PVE, before the correction all lesions gave an average max SUV of 7.83. And after the correction, the average max SUV increases to 10.31. The differences in the max SUV between before and after correction were analyzed by paired t test. As a result, there were statistically significant differences (t=7.21, p=0.000). Conclusion: The SUV for quantification should be measured precisely to give consistent information of tumor uptake. But PVE is one of factors that causes SUV to be lower and to be underestimated. We can correct this PVE and calculate corrected SUV using the recovery coefficient from phantom study. And if we apply this correction method to clinical patients, we can finally assess and provide quantitative analysis more accurately.

• Journal of Biomedical Engineering Research
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• v.32 no.3
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• pp.251-256
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• 2011

Virtual colonoscopy is favored over conventional colonoscopy because its non-invasive procedure can avoid complications that may happen in a conventional approach and because it can cleanse colon electronically instead of uncomfortable conventional colon cleansing. Electronic Colon Cleansing(ECC) has to deal with not only removing tagged fecal material but also recovering Partial Volume Effect(PVE) due to tagging material. This paper proposes an ECC method restoring inherent natural PVE while previous approaches focused only on reducing PVE due to tagged fecal material. The proposed method reduces PVE using 3-dimensional adaptive density correction and then replaces tagged fecal material into air. Next, it generates natural PVE for the replaced air adjacent to soft tissue and finally makes smooth transition of gray values for soft tissue adjacent to the replaced air. The proposed method applied to eleven patient data, and showed promising results.

• Journal of the Korean Society of Radiology
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• v.9 no.3
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• pp.139-145
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• 2015

When examining a patient using SPECT, gamma rays emitted from the body decrease or scatter. And when they reach the detector they spread in accordance with physical characteristics and geometric shapes of the scanner, quantitative analysis was difficult. For exact quantitative analysis of gamma rays emitted from the body, so that they must be considered to correction about PVE(partial volume effect). In this paper, sinogram filter was implemented to solve comprehensive PVE of SPECT. According to the results in which implemented filter was applied, partial volume effect caused by SPECT was removed. To compare proposed method and conventional method, PSNR(Peak Signal to Noise Ratio) was executed. As a result, proposed method was indicated as 7dB, conventional method was indicated as 14db respectively. dB(decibel) level of the proposed methods is lower, since the MSE(mean square error) becomes greater because scattered ray was removed, PSNR value is low. Therefore, by applying the proposed method for removing the PVE of SPECT imaging method, the image quality is improved.

• Clinical and Experimental Pediatrics
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• v.55 no.1
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• pp.24-28
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• 2012

Partial anomalous pulmonary vein connection (PAPVC) is a rare congenital abnormal cardiac defect involving the pulmonary veins draining into the right atrium (RA) directly or indirectly by venous connection. Ninety percent of PAPVCs are accompanied by atrial septal defect (ASD). To our knowledge, there is no previous report of PAPVC with ventricular septal defect (VSD) without ASD in Korea, and in this paper, we report the first such case. A 2-day-old girl was admitted into the Chonnam National University Hospital for evaluation of a cardiac murmur. An echocardiogram revealed perimembranous VSD without ASD. She underwent patch closure of the VSD at 5 months of age. Although the VSD was completely closed, she had persistent cardiomegaly with right ventricular volume overload, as revealed by echocardiography. Three years later, cardiac catheterization and chest computed tomography revealed a PAPVC, with the right upper pulmonary vein draining into the right SVC. Therefore, correction of the PAPVC was surgically performed at 3 years of age. We conclude that it is important to suspect PAPVC in patients with right ventricular volume overload, but without ASD.

• Progress in Medical Physics
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• v.9 no.3
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• pp.163-173
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• 1998

Nuclear medicine emission computed tomography(ECT) can be very useful to diagnose early stage of neuronal diseases and to measure theraputic results objectively, if we can quantitate energy metabolism, blood flow, biochemical processes, or dopamine receptor and transporter using ECT. However, physical factors including attenuation, scatter, partial volume effect, noise, and reconstruction algorithm make it very difficult to quantitate independent of type of SPECT. In this study, we quantitated the effects of attenuation and scatter using brain SPECT and three-dimensional brain phantom with and without applying their correction methods. Dual energy window method was applied for scatter correction. The photopeak energy window and scatter energy window were set to 140ke${\pm}$10% and 119ke${\pm}$6% and 100% of scatter window data were subtracted from the photopeak window prior to reconstruction. The projection data were reconstructed using Butterworth filter with cutoff frequency of 0.95cycles/cm and order of 10. Attenuation correction was done by Chang's method with attenuation coefficients of 0.12/cm and 0.15/cm for the reconstruction data without scatter correction and with scatter correction, respectively. For quantitation, regions of interest (ROIs) were drawn on the three slices selected at the level of the basal ganglia. Without scatter correction, the ratios of ROI average values between basal ganglia and background with attenuation correction and without attenuation correction were 2.2 and 2.1, respectively. However, the ratios between basal ganglia and background were very similar for with and without attenuation correction. With scatter correction, the ratios of ROI average values between basal ganglia and background with attenuation correction and without attenuation correction were 2.69 and 2.64, respectively. These results indicate that the attenuation correction is necessary for the quantitation. When true ratios between basal ganglia and background were 6.58, 4.68, 1.86, the measured ratios with scatter and attenuation correction were 76%, 80%, 82% of their true ratios, respectively. The approximate 20% underestimation could be partially due to the effect of partial volume and reconstruction algorithm which we have not investigated in this study, and partially due to imperfect scatter and attenuation correction methods that we have applied in consideration of clinical applications.

• Archives of Plastic Surgery
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• v.39 no.5
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• pp.489-496
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• 2012

Background In Korean women, many of whom have small to moderate-sized breasts, it is difficult to cover a partial breast defect using oncoplastic volume displacement techniques after removal of an adequate volume of tissue during oncologic surgery. In such cases, oncoplastic volume replacement techniques are more useful. Methods From January 2007 to December 2011, 104 women underwent a total of 107 breast-conserving surgeries with various kinds of oncoplastic volume replacement techniques. We used latissimus dorsi (LD) myocutaneous flap for cases in which the resection mass was greater than 150 g. In case with a resection mass less than 150 g, we used regional flaps such as a lateral thoracodorsal flap, a thoracoepigastric flap, or perforator flaps such as an intercostal artery perforator (ICAP) flap or a thoracodorsal artery perforator (TDAP) flap. Results The mean age was 46.1 years, and the average follow-up interval was 10.3 months. The patients underwent oncoplastic volume replacement techniques with a lateral thoracodorsal flap (n=9), thoracoepigastric flap (n=7), ICAP flap (n=25), TDAP flap (n=12), and LD flap (n=54). There was one case of congestion in an LD flap, and two cases of fat necrosis in an ICAP flap. Most of the patients were satisfied with the cosmetic results. Conclusions Oncoplastic volume replacement techniques can be reliable and useful for the correction of breast deformity after breast-conserving surgery, especially in patients with small to moderate-sized breasts.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.2
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• pp.71-77
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• 2007

Advance of neuroimaging technique has greatly influenced recent brain research field. Among various neuroimaging modalities, positron emission tomography has played a key role in molecular neuroimaging though functional MRI has taken over its role in the cognitive neuroscience. As the analysis technique for PET data is more sophisticated, the complexity of the method is more increasing. Despite the wide usage of the neuroimaging techniques, the assumption and limitation of procedures have not often been dealt with for the clinician and researchers, which might be critical for reliability and interpretation of the results. In the current paper, steps of voxel-based statistical analysis of PET including preprocessing, intensity normalization, spatial normalization, and partial volume correction will be revisited in terms of the principles and limitations. Additionally, new image analysis techniques such as surface-based PET analysis, correlational analysis and multimodal imaging by combining PET and DTI, PET and TMS or EEG will also be discussed.