• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.68-80
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• 2012

Purpose : More recently, combined PET/MR scanners have been developed in which the MR data can be used for both anatometabolic image formation and attenuation correction of the PET data. For quantitative PET information, correction of tissue photon attenuation is mandatory. The attenuation map is obtained from the CT scan in the PET/CT. In the case of PET/MR, the attenuation map can be calculated from the MR image. The purpose of this study was to assess the quantitative differences between MR-based and CT-based attenuation corrected PET images. Materials and Methods : Using the uniform cylinder phantom of distilled water which has 199.8 MBq of $^{18}F$-FDG put into the phantom, we studied the effect of MR-based and CT-based attenuation corrected PET images, of the PET-CT using time of flight (TOF) and non-TOF iterative reconstruction. The images were acquired from 60 minutes at 15-minute intervals. Region of interests were drawn over 70% from the center of the image, and the Scanners' analysis software tools calculated both maximum and mean SUV. These data were analyzed by one way-anova test and Bland-Altman analysis. MR images are segmented into three classes(not including bone), and each class is assigned to each region based on the expected average attenuation of each region. For clinical diagnostic purpose, PET/MR and PET/CT images were acquired in 23 patients (Ingenuity TF PET/MR, Gemini TF64). PET/CT scans were performed approximately 33.8 minutes after the beginnig of the PET/MR scans. Region of interests were drawn over 9 regions of interest(lung, liver, spleen, bone), and the Scanners' analysis software tools calculated both maximum and mean SUV. The SUVs from 9 regions of interest in MR-based PET images and in CT-based PET images were compared. These data were analyzed by paired t test and Bland-Altman analysis. Results : In phantom study, MR-based attenuation corrected PET images generally showed slightly lower -0.36~-0.15 SUVs than CT-based attenuation corrected PET images (p<0.05). In clinical study, MR-based attenuation corrected PET images generally showed slightly lower SUVs than CT-based attenuation corrected PET images (excepting left middle lung and transverse Lumbar) (p<0.05). And percent differences were -8.01.79% lower for the PET/MR images than for the PET/CT images. (excepting lung) Based on the Bland-Altman method, the agreement between the two methods was considered good. Conclusion : PET/MR confirms generally lower SUVs than PET/CT. But, there were no difference in the clinical interpretations made by the quantitative comparisons with both type of attenuation map.

• Journal of KIISE:Software and Applications
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• v.36 no.8
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• pp.623-632
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• 2009

In this paper, we propose a pulmonary nodule registration for the tracking of lung nodules in sequential CT scans. Our method consists of following five steps. First, a translational mismatch is corrected by aligning the center of optimal bounding volumes including each segmented lung. Second, coronal maximum intensity projection(MIP) images including a rib structure which has the highest intensity region in baseline and follow-up CT series are generated. Third, rigid transformations are optimized by normalized average density differences between coronal MIP images. Forth, corresponding nodule candidates are defined by Euclidean distance measure after rigid registration. Finally, template matching is performed between the nodule template in baseline CT image and the search volume in follow-up CT image for the nodule matching. To evaluate the result of our method, we performed the visual inspection, accuracy and processing time. The experimental results show that nodules in serial CT scans can be rapidly and correctly registered by coronal MIP-based rigid registration and local template matching.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.214-227
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• 2013

Computed tomographic scan as a screening procedures in asymptomatic individuals has seen a steady increase with the introduction of multiple-raw detector CT scanners. This report provides a brief review of the current controversy surrounding CT cancer screening, with a focus on the radiation induced cancer risks and clinical efficacy. 1. A large study of patients at high risk of lung cancer(the National Lung Screening Trial[NLST]) showed that CT screening reduced cancer deaths by 20%(1.33% in those screened compared with 1.67% in those not screened). The rate of positive screening tests was 24.2% and 96.4% of the positive screening results in the low-dose CT group were false-positive. Radiation induced lung cancer risk was estimated the most important in screening population because ERR of radiation induced lung cancer does not show the decrease with increasing age and synergistic connection between smoking and radiation risk. Therefore, the radiation risk may be on the same order of magnitude as the benefit observed in the NLST. Optimal screening strategy remain uncertain, CT lung cancer screening is not yet ready for implementation. 2. Computed tomographic colonography is as good as colonoscopy for detecting colon cancer and is almost as good as colonoscopy for detecting advanced adenomas, but significantly less sensitive and specific for smaller lesions and disadvantageous for subsequent therapeutic optical colonoscopy if polyps are detected. The average effective dose from CT colonography was estimated 8-10 $mS{\nu}$, which could be a significant dose if administered routinely within the population over many years. CT colonography should a) achieve at least 90% sensitivity and specificity in the size category from 6 and 10 mm, b) offer non-cathartic bowl preparation and c) be optimized and standardized CT parameters if it is to be used for mass screening. 3. There is little evidence that demonstrates, for whole-body scanning, the benefit outweighs the detriment. This test found large portion of patient(86~90.8%) had at least one abnormal finding, whereas only 2% were estimated to have clinically significant disease. Annual scans from ages 45 to 75 years would accrue an estimated lifetime cancer mortality risk of 1.9%. There is no group within the medical community that recommends whole-body CT. No good studies indicate the accuracy of screening CT, at this time. The benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established. These areas need further research. Therefore wild screening should be avoided.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.505-515
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• 1997

Background : We assessed the accuracy of staging in evaluation of bronchial invasion, thus found the role of CT in patients who underwent resective surgery in primary lung cancer. Materials and Methods : Authors retrospectively analized the preoperative CT scans of 156 patients receiving pneumonectomy(n = 95) and lobectomy(n = 61). Among lobectomy patients, 7 patients subsequently performed pneumonectomy because of positive resection margin of bronchus in frozen biopsy. We also retrospectively analized CT scans of non-operated 60 patients who performed sufficient bronchoscopic biopsy. Bronchial wall thickness more than 3mm, irregular wall thickening and reduction of diameter by CT were defined as bronchial invasion. The pathologic examination of resection margin were positive in 20, stump recurrence occurred in 6 of the operated group, and the pathologic examination of biopsy of bronchial wall were positive in 34 of the non operated group, and these were an regarded as bronchial invasion. Results : The CT assessment of bronchial invasion revealed low sensitivity (11.5%), low positive predictability(38%), but high specificity(96%) and relatively high accuracy (84%) in the operated group and higher sensitivity (62%), higher positive predictability(95%) in non-operated group. Conclusion : In lung cancer patients who underwent operation, CT showed very low sensitivity and positive predictability in evaluation of bronchial invasion. Because the usefulness of CT in evaluation of bronchial invasion is limited, therefore aggressive fiberoptic bronchoscopic biopsy is thought to be necessary before surgical attempt.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.3
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• pp.163-168
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• 2006

Purpose: Incidence of lung canter in patients with idiopathic pulmonary fibrosis (IPF) is known to be higher than that in general population. However, it is difficult to discriminate pulmonary nodule in patients with IPF, because underlying IPF can be expressed as lung nodules. We evaluated the diagnostic performance of FDG PET in discriminating lung nodule in patients with IPF. Methods: We retrospectively reviewed 28 lung nodules in 16 subjects (age; $67.53{\pm}9.53$, M:F=14:2). Two patients had previous history of malignant cancer (small cell lung cancer and subglottic cancer). The diagnostic criteria on chest CT were size, morphology and serial changes of size. FDG PET was visually interpreted, and maximal SUV was calculated for quantitative analysis. Results: from 28 nodules, 18 nodules were interpreted as benign nodules, 10 nodules as malignant nodules by histopahthology or follow-up chest CT. The sensitivity and specificity of FDG PET were 100% and 94.4%, while those of CT were 70.0% and 44.4%, respectively. Malignant nodule was higher maxSUV than that of benign lung nodules ($7.68{\pm}3.96\;vs.\;1.22{\pm}0.65$, p<0.001). Inflammatory lesion in underlying IPF was significantly lower maxSUV than that of malignant nodules ($1.80{\pm}0.43$, p<0.001). The size of malignant and benign nodule were $23.95{\pm}10.15mm\;and\;10.83{\pm}5.23mm$ (p<0.01). Conclusion: FDG PET showed superior diagnostic performance to chest CT in differentiating lung nodules in patients with underlying IPF. FDG PET could be used to evaluate suspicious malignant lung nodule detected by chest in patients with IPF.

• Radiation Oncology Journal
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• v.35 no.2
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• pp.180-184
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• 2017

Patients with locally advanced lung cancer and very limited pulmonary function (forced expiratory volume in 1 second $[FEV1]{\leq}1L$) have dismal prognosis and undergo palliative treatment or best supportive care. We describe two cases of locally advanced node-positive non-small cell lung cancer (NSCLC) patients with very limited lung function treated with induction chemotherapy and moderate hypofractionated image-guided radiotherapy (Hypo-IGRT). Hypo-IGRT was delivered to a total dose of 45 Gy to the primary tumor and involved lymph nodes. Planning was based on positron emission tomography-computed tomography (PET/CT) and four-dimensional computed tomography (4D-CT). Internal target volume (ITV) was defined as the overlap of gross tumor volume delineated on 10 phases of 4D-CT. ITV to planning target volume margin was 5 mm in all directions. Both patients showed good clinical and radiological response. No relevant toxicity was documented. Hypo-IGRT is feasible treatment option in locally advanced node-positive NSCLC patients with very limited lung function ($FEV1{\leq}1L$).

• Progress in Medical Physics
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• v.4 no.2
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• pp.19-25
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• 1993

Treatment planning of lung cancer with density corrected Computed tomography. Eighty-seven patients with lung cnacer who had radiation therapy in Yeungnam University Medical Center between, April 1 1990 and Aug. 30 1993 were retrospectively evaluated total tumor dose, dose distribution, field correction, and loading change, compared with contour or CT image planning and density corrected CT planning. In dose distribution, higher dose was calculated in compare with density corrected CT planning less than 5% difference were found in 45 patient(52%), 5-10% in 25 patients (29%), 10-15% in 15 patients (17%) and over 15% in 2 patients (2%). Correction of treatment field was performed in 18 patients (21%) and changing of dose loading was given in 15 patients (17%). In conclusion, we emphasize that density corrected CT planning is the very important factor which contribute to increase therapeutic gain by exact selection of target volume, target dose, normal tissue dose and dose of critical organ.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.1
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• pp.87-92
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• 2016

In this paper, we improved classification performance of benign and malignant lung nodules by including the parenchyma features. For small pulmonary nodules (4-10mm) nodules, there are a limited number of CT data voxels within the solid tumor, making them difficult to process through traditional CAD(computer aided diagnosis) tools. Increasing feature extraction to include the surrounding parenchyma will increase the CT voxel set for analysis in these very small pulmonary nodule cases and likely improve diagnostic performance while keeping the CAD tool flexible to scanner model and parameters. In AdaBoost learning using naive Bayes and SVM weak classifier, a number of significant features were selected from 304 features. The results from the COPDGene test yielded an accuracy, sensitivity and specificity of 100%. Therefore proposed method can be used for the computer aided diagnosis effectively.

• Korean Journal of Radiology
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• v.23 no.10
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• pp.998-1008
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• 2022

Objective: The present study aimed to assess the relationship between incidental abnormalities on thoracic computed tomography (CT) and mortality in a general screening population using a long-term follow-up analysis. Materials and Methods: We retrospectively collected the medical records and CT images of 840 participants (mean age ± standard deviation [SD], 58.5 ± 6.7 years; 564 male) who underwent thoracic CT at a single health promotion center between 2007 and 2010. Two thoracic radiologists independently reviewed all CT images and evaluated any incidental abnormalities (interstitial lung abnormality [ILA], emphysema, coronary artery calcification [CAC], aortic valve [AV] calcification, and pulmonary nodules). Kaplan-Meier analysis with log-rank and z-tests was performed to assess the relationship between incidental CT abnormalities and all-cause mortality in the subsequent follow-up. Cox proportional hazards regression was performed to further identify risk factors of all-cause mortality among the incidental CT abnormalities and clinical factors. Results: Among the 840 participants, 55 (6%), 171 (20%), 288 (34%), 396 (47%), and 97 (11%) had findings of ILA, emphysema, CAC, pulmonary nodule, and AV calcification, respectively, on initial CT. The participants were followed up for a mean period ± SD of 10.9 ± 1.4 years. All incidental CT abnormalities were associated with all-cause mortality in univariable analysis (p < 0.05). However, multivariable analysis further revealed fibrotic ILA as an independent risk factor for all-cause mortality (hazard ratio, 2.52 [95% confidence interval, 1.02-6.22], p = 0.046). ILA were also identified as an independent risk factor for lung cancer or respiratory disease-related deaths. Conclusion: Incidental abnormalities on screening thoracic CT were associated with increased mortality during the long-term follow-up. Among incidental CT abnormalities, fibrotic ILA were independently associated with increased mortality. Appropriate management and surveillance may be required for patients with fibrotic ILA on thoracic CT obtained for general screening purposes.

• Journal of radiological science and technology
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• v.35 no.1
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• pp.59-64
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• 2012

Recently, SPECT/CT system has been applied to many diseases, however, the application is not extensively applied at pulmonary disease. Especially, in case that, the pulmonary embolisms suspect at the CT images, SPECT is performed. For the accurate diagnosis, SPECT/CT tests are subsequently undergoing.However, without SPECT/CT, there are some limitations to apply these procedures. With SPECT/CT, although, most of the examination performed after CT. Moreover, such a test procedures generate unnecessary dual irradiation problem to the patient. In this study, we evaluated the amount of unnecessary irradiation, and the usefulness of fusion images of pulmonary disease, which independently acquired from SPECT and CT. Using NEMA PhantomTM (NU2-2001), SPECT and CT scan were performed for fusion images. From June 2011 to September 2010, 10 patients who didn't have other personal history, except lung disease were selected (male: 7, female: 3, mean age: $65.3{\pm}12.7$). In both clinical patient and phantom data, the fusion images scored higher than SPECT and CT images. The fusion images, which is combined with pulmonary vessel images from CT and functional images from SPECT, can increase the detection possibility in detecting pulmonary embolism in the resin of lung parenchyma. It is sure that performing SPECT and CT in integral SPECT/CT system were better. However, we believe this protocol can give more informative data to have more accurate diagnosis in the hospital without integral SPECT/CT system.