• Nuclear Medicine and Molecular Imaging
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• v.41 no.3
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• pp.247-251
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• 2007

A 38-year-old man who was diagnosed with malignant paraganglioma underwent computed tomography (CT) and I-131 metaiodobenzylguanidine (MIBG) san. CT showed extensive lymph node enlargement in right iliac area and retroperitoneum with severe hydronephrosis and mass on posterior bladder wall. However, I-131 MIBG scan didn't showed abnormal uptake. He also underwent F-18 fluorodeoxyglucose (FDG) positron emisson tomography/CT for localizing accurate tumor site. F-18 FDG PET/CT showed multiple metastases of left supraclavicular, hilar, mediastinal para-aortic, inguinal, right iliac lymph nodes, lung, vertebrae, and pelvis. There are a few reports showing that the F-18 FDG PET/CT is helpful for staging and localizing tumor site of patients who are diagnosed with negative on the MIBG scans. Thus, we report a case with paraganglioma which showed negative I-131 MIBG scan, but revealed multiple intense hypermetabolic foci in F-18 FDG PET/CT.

• The Korean Journal of Pain
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• v.19 no.1
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• pp.51-55
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• 2006

Background: A cervical transforaminal steroid injection is an effective therapeutic modality for radiculopathy of a herniated cervical disc or a cervical foraminal stenosis. However, there is some debate regarding the safety of the transforaminal approach under C-arm guidance compared with the posterior interlaminar approach. We report a new technique for cervical transforaminal steroid injection guided by MDCT. Methods: Patients presenting with radiating pain on their shoulder or arm were diagnosed using CT or MRI of a cervical herniated disc or a foraminal stenosis. Each patient whose symptoms were compatible with the image scan was enrolled in this study. They received a cervical transforaminal steroid injection under CT guidance, and the effectiveness and complications of this technique were evaluated over a 2-month period. Results: According to the CT scan, none of the participants had an internal jugular vein or a carotid artery invasion during the procedure. No vertebral artery injection was noted, and no patient developed a hematoma after the injection. The VAS score had improved significantly by 2, 4 and 8 weeks after the injection. Conclusions: While a conventional C-arm guided cervical transforaminal steroid injection does not appear to differentiate between the major vessels and structures in images, a CT guided approach is a more useful and safer technique for the precise placement of a needle.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.169-178
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• 2020

The number of CT scans is increasing every year due to the improvement of the medical standards of the public, and thus the annual dose of medical radiation is also increasing. In this study, we evaluated the effective dose of the human body exposed to CT scans and estimated LAR. First, five region were selected from the CT diagnostic reference level guideline, and the effective dose of human body exposed to each examination was evaluated by clinical CT device. Second, the human organs and effective dose were calculated using the ALARA-CT program under the same conditions. Third, lifetime attributable risk (LAR) estimated by the effective dose exposed through the previous CT scan was estimated. As a result, the most effective dose was 21.18 mSv during the abdomen 4 phase scan, and the dose level was below DRL for all other tests except for the abdominal examination. As a result of evaluating effective dose using a dose calculation program under the same conditions, the results showed about 1.1 to 1.9 times higher results for each examination. In the case of organ dose, the closer the organ to the scan site, the higher the scattering ray. The lifetime attributable risk to CT radiation dose in adults was gradually decreased with age, and the results were somewhat different according to gender.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.126-129
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• 2008

Renal cell carcinoma is the most common histological type of renal malignancy, predominant in men and the primary treatment modality of this tumor is surgery. The role of diagnostic imaging in the management of this tumor is the evaluation of extent of disease as well as the detection and characterization of renal mass. US has long been a routine screening tool for kidney but tomographic imaging modalities such as CT and MRI begin to be also commonly used these days. On the other hand, the sensitivity of $^{18}F-FDG-PET$ in detection of renal mass is relatively low because of inherent limitation caused by FDG excretion pathway despite avid uptake of FDG to tumor cell per se. Many studies revealed FDG PET scan could play an important role in detection of metastatic lesions although the sensitivity for the detection of primary lesion is not so high. Furthermore, development of PET/CT scanner will make it possible to expand the indication of FDG PET scan in this malignancy.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.71-75
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• 2013

Purpose: Currently, decrement revision using LDCT is used in PET/CT. But cold artifacts are often found in decrement revision image by mismatch between LDCT image and Emission image near diaphragm due to patient's respiration. This research studied reduction of cold artifact by patient's respiration using CTAC Shift among revision methods. Materials and Methods: From March to September in 2012, 30 patients who had cold artifacts by respiration were targeted using PET/CT Discovery 600 (GE Healthcare, MI, USA) equipment. Patients with cold artifacts were additionally scan in diaphragm area, and the image shown cold artifacts at whole body test were revised using CTAC Shift. Cold artifacts including image, additional scan image and CTAC Shift revision image were evaluated as 1~5 points with naked eye by one nuclear medicine expert, 4 radiotechnologists with over 5 year experience. Also, standard uptake value of 3 images was compared using paired t-test. Results: Additional scan image and CTAC Shift revision image received relatively higher score in naked eye evaluation than cold artifacts including image. The additional scan image and CTAC Shift revision image had high correlation as the results of ANOVA test of standard uptake value and did not show significant difference. Conclusion: When cold artifacts are appeared by patient's respiration at PET/CT, it causes not only patient inconvenience but troubles in test schedule due to extra radiation exposure and time consumption by additional scan. But if CTAC Shift revision image can be acquired with out additional scan, it is considered to be helped in exact diagnosis without unnecessary extra radiation exposure and additional scan.

• Tuberculosis and Respiratory Diseases
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• v.81 no.1
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• pp.49-58
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• 2018

Background: Information regarding the incidence and risk factors for deep vein thrombosis (DVT) detected by follow-up computed tomographic (CT) venography after pulmonary embolism (PE) is sparse. The aim of the present study was to identify the predictors of DVT in follow-up CT images, and to elucidate their clinical significance. Methods: Patients with PE were classified into the following three cohorts based on the time of indirect CT venography follow-up: within 1 month, 1 to 3 months, and 3 to 9 months after the initial CT scan. Each cohort was subdivided into patients with or without DVT detected by follow-up CT. Clinical variables were compared between the two groups. Results: Follow-up CT revealed DVT in 61% of patients with PE within 1 month, in 15% of patients with PE at 1 to 3 months, and in 9% of patients with PE at 3 to 9 months after the initial CT scan. Right ventricular (RV) dilation on the initial CT (odds ratio [OR], 8.30; 95% confidence interval [CI], 1.89-36.40; p=0.005) and proximal DVT at the initial presentation (OR, 6.93; 95% CI, 1.90-25.20; p=0.003) were found to independently predict DVT in follow-up CT images within 1 month, proximal DVT at the initial presentation was found to independently predict DVT in follow-up CT images at 1 to 3 months (OR, 6.69; 95% CI, 1.53-29.23; p=0.012), and central PE was found to independently predict DVT in follow-up CT images at 3 to 9 months (OR, 4.25; 95% CI, 1.22-4.83; p=0.023) after the initial CT scan. Furthermore, the detection of DVT by follow-up CT independently predicted the recurrence of venous thromboembolism (VTE) (OR, 4.67; 95% CI, 2.24-9.74; p<0.001). Conclusion: Three months after PE, DVT was not detected by follow-up CT in most patients with PE. RV dilation on the initial CT, central PE, and proximal DVT at the initial presentation were found to predict DVT on follow-up CT, which might predict VTE recurrence.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.4
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• pp.1707-1710
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• 2014

Background: The objective of this study was to evaluate baseline use and positive rates of staging images (bone scan, CT) in newly diagnosed patients with prostate cancer (PCa) and to improve staging image overuse. Materials and Methods: This retrospective study covered a consecutive series of patients with PCa who underwent stage imaging at our institution between 2006 and 2011. Various clinical and pathological variables (age, PSA, biopsy Gleason score, clinical T stage, positive biopsy core rate) were evaluated by multivariate logistic regression analysis for their ability to predict a positive staging image. All patients were stratified according to the NCCN risk stratification and positive rates were compared in each risk group. Results: 410 patients (100%) underwent a bone scan and 315 patients (76.8%) underwent a CT scan. Some 51 patients (12.4%) had a positive bone scan, clinical T3 and T4 being significant independent predictors. Positive bone scan rates for low-, intermediate-, high-, and very high-risk groups were 0%, 0%, 8.25%, and 56.6%. Some 59 (18.7%) patients had a positive CT scan, with elevated PSA and clinical T3, T4 as significant independent predictors. Low-, intermediate-, high- and very high-risk group rates were 0%, 0%, 13.8% and 80.0%. Conclusions: The incidences of positive staging image in low- and intermediate- risk group were reasonably low. Following feedback on these results, staging in low- and intermediate- risk groups could be omitted.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.110-114
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• 2017

Because the arm can't be sutured due to fracture during a elbow CT scan, a CT scan is proceeded in a state of abdomen and L-spire are overlapped which beam hardening artifact is done many times, and it often lowers the quality of elbow CT images. So there are many difficulties in reading and due to increase in radiation dose from it, the number of patient's exposure keeps increasing. In this research, it plans to improve the quality of the images by avoiding overlap with abdomen, and increasing the number of photon overlapped with lung field which the line attenuation is relatively small. The way of experiment is based on patient's right elbow and place him as head first position, then place his elbow at L2-3 level in supine position, turn about 30 degrees to the left in non-control breathing and in supine position, and compared with full inspiration after overlapping with lung. After figuring out the average value and standard deviation data using Image J program 5 times each for 16, 128 channels, the evaluation is proceeded by measuring each of CNR, MSR are statistically analyzed using SPSS program. Therefore, through positioning and inspiration during elbow CT scan, the way of inspection minimized the exposure radiation dose, and seems to be meaningful in a way to improve the quality of the images.

• Journal of the Korean Society of Radiology
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• v.82 no.6
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• pp.1493-1504
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• 2021

Purpose This study aimed to evaluate the utility of the 16-cm axial volume scan technique for calculating the coronary artery calcium score (CACS) using non-enhanced chest CT. Materials and Methods This study prospectively enrolled 20 participants who underwent both, non-enhanced chest CT (16-cm-coverage axial volume scan technique) and calcium-score CT, with the same parameters, differing only in slice thickness (in non-enhanced chest CT = 0.625, 1.25, 2.5 mm; in calcium score CT = 2.5 mm). The CACS was calculated using the conventional Agatston method. The difference between the CACS obtained from the two CT scans was compared, and the degree of agreement for the clinical significance of the CACS was confirmed through sectional analysis. Each calcified lesion was classified by location and size, and a one-to-one comparison of non-contrast-enhanced chest CT and calcium score CT was performed. Results The correlation coefficients of the CACS obtained from the two CT scans for slice thickness of 2.5, 1.25, and 0.625 mm were 0.9850, 0.9688, and 0.9834, respectively. The mean differences between the CACS were -21.4% at 0.625 mm, -39.4% at 1.25 mm, and -76.2% at 2.5 mm slice thicknesses. Sectional analysis revealed that 16 (80%), 16 (80%), and 13 (65%) patients showed agreement for the degree of coronary artery disease at each slice interval, respectively. Inter-reader agreement was high for each slice interval. The 0.625 mm CT showed the highest sensitivity for detecting calcified lesions. Conclusion The values in the non-contrast-enhanced chest CT, using the 16-cm axial volume scan technique, were similar to those obtained using the CACS in the calcium score CT, at 0.625 mm slice thickness without electrocardiogram gating. This can ultimately help predict cardiovascular risk without additional radiation exposure.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.2
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• pp.451-458
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• 1999

Purpose : To determine normal CT number range of parotid gland by analyzing the change by age increase and the difference among individuals and between both sexes in CT number of normal parotid gland. Materials & Methods : 134 subjects who took the CT scan between the period of Jan. 1996 and Dec. 1997 at Yonsei University, Dental Hospital were selected. Criteria for selection were that the patients must be within the normal range clinically and radiologically, and the entire parotid gland on the axial view must be shown. Among the axial views. the one showing the greatest parotid gland size was selected and its CT number was recorded. Also. CT numbers from both masseter muscle were recorded as its control. Results : There was statistically significant correlation between CT number of right and left of parotid glands and masseter muscles. With the increase of age. there is a significant decrease in the CT number of parotid gland(p<0.05). There was no statistically significant difference in CT number between sexes except the 7th decade and beyond age group of parotid gland(p>0.05). Conclusion : As age increases, CT number of parotid gland has a tendency to decrease, and there is no significant difference in the CT numbers between left and right parotid gland. Therefore in the CT scan of patients suspected of having a salivary gland disease of the parotid gland. to consider normal range of the age-dependent CT numbers of parotid gland and compare the CT numbers of the right and left parotid gland might be useful in diagnosing the disease.