• Journal of the Korea Society of Computer and Information
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• v.24 no.3
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• pp.41-47
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• 2019

In this paper, we propose a application of conditional generative adversarial network (cGAN) for generation of contrast enhanced computed tomography (CT) image. Two types of CT data which were the enhanced and non-enhanced were used and applied by the histogram equalization for adjusting image intensities. In order to validate the generation of contrast enhanced CT data, the structural similarity index measurement (SSIM) was performed. Prepared generated contrast CT data were analyzed the statistical analysis using paired sample t-test. In order to apply the optimized algorithm for the lymph node cancer, they were calculated by short to long axis ratio (S/L) method. In the case of the model trained with CT data and their histogram equalized SSIM were $0.905{\pm}0.048$ and $0.908{\pm}0.047$. The tumor S/L of generated contrast enhanced CT data were validated similar to the ground truth when they were compared to scanned contrast enhanced CT data. It is expected that advantages of Generated contrast enhanced CT data based on deep learning are a cost-effective and less radiation exposure as well as further anatomical information with non-enhanced CT data.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.3
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• pp.209-217
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• 2008

Purpose: To date, anatomical imaging modalities of the pelvis and tumor markers have been the mainstay of surveillance for recurrent ovary cancer. This study aimed to assess the role of $^{18}F$-FDG PET/CT in evaluation of ovary cancer recurrences, especially in comparison with enhanced a and tumor marker CA 125. Materials and methods: 73 patients who had PET/CT scan for restaging of confirmed ovary cancer, and additional imaging with enhanced a of the pelvis within one month were included. CA 125 level was available in all patients. From the PET/CT images, maximum standard uptake values (SUVmax) of suspected recurrence sites were recorded. Confirmation was available through re-operation or biopsy in 26 cases, and clinical assessment with series of follow-up images in 47. Results: PET/CT had 93% sensitivity and 88% specificity for detecting recurrent ovary cancer. Enhanced a of pelvis had sensitivity and specificity of 83% and 88%, and CA 125 50% and 95%. Conclusion: PET/CT has higher sensitivity for detecting recurrent ovary cancer compared to enhanced a though the differences were not significant. PET/CT has significantly higher sensitivity than CA 125. However, the three tests all agreed in only 43% of the recurrence cases, and recurrence should be suspected when any of the tests, especially PET/CT, show positive findings.

• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.270-279
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• 2012

This paper explores CT findings of a rabbit brain infection model injected with Escherichia coli and investigates the changes in Hounsfield unit (HU) of arterial blood over time. The brain infection model was produced by injecting E. coli $1{\times}10^7$ CFU/ml, 0.1 ml through the burr hole in the calvarium; 2~3 mm in depth from the dura mater, and contrast-enhanced CT, dynamic CT and arterial blood CT images were gained. It was found that various brain infections such as brain abscess, ventriculitis and meningitis. The CT image of brain abscess showed a typical pattern which the peripheral area was strongly contrast-enhanced while the center was weakly contrast-enhanced. The CT image of ventriculitis showed a strong contrast-enhancement along the lateral ventricle wall, and the CT image of meningitis showed a strong contrast-enhancement in the area between the telencephalon and the diencephalon. In dynamic CT images, the HU value of the infection core before injecting contrast medium was $31.01{\pm}3.55$. By 10 minutes after the injection, the value increased gradually to $40.36{\pm}3.76$. The HU value in the areas of the marginal rim where was hyper-enhanced showed $47.23{\pm}3.12$ before contrast injection, and it increased to $63.59{\pm}3.31$ about 45 seconds after the injection. In addition, the HU value of the normal brain tissue opposite to the E. coli. injected brain was $39.01{\pm}3.24$ before the injection, but after the contrast injection, the value increased to $49.01{\pm}4.29$ in about 30 seconds, and then it showed a gradual decline. In the arterial blood CT, the HU value before the contrast injection was $87.78{\pm}6.88$, and it increased dramatically between 10 to 30 seconds until it reached a maximum value of $749.13{\pm}98.48$. Then it fell sharply to $467.85{\pm}62.98$ between 30 seconds to 45 seconds and reached a plateau by 60 seconds. Later, the value showed a steady decrease and indicated $188.28{\pm}25.03$ at 20 minutes. Through this experiment, it was demonstrated that the brain infection model can be produced by injecting E. coli., and the characteristic of the infection model can be well observed with contrast-enhanced CT scan. The dynamic CT scan showed that the center of the infection was gradually contrast-enhanced, whereases the peripheral area was rapidly contrast-enhanced and then slowly decreased. As for arterial blood, it increased significantly between 10 seconds to 30 seconds after the contrast medium injection and decreased gradually after reaching a plateau.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.8
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• pp.4071-4075
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• 2016

Background: FDG PET/CT is at an equivocal stage to recommend for staging of colorectal cancer as compared to contrast-enhanced CT (ceCT). This study was intended to evaluate the value of FDG PET/ceCT in colorectal cancer staging as compared to ceCT alone. Materials and Methods: PET/ceCT was performed for 61 colorectal cancer patients who were prospectively enrolled in the study. Three patients were excluded due to loss to follow-up. PET/ceCT findings and ceCT results alone were read separately. The treatment planning was then determined by tumor board consensus. The criteria for T staging were determined by the findings of ceCT. Nodal positive by PET/ceCT imaging was determined by visual analysis of FDG uptake greater than regional background blood pool activity. The diagnostic accuracy of T and N staging was determined only in patients who received surgery without any neoadjuvant treatment. Results: Of 58 patients, there were 40 with colon cancers including sigmoid cancers and 18 with rectal cancers. PET/ceCT in pre-operative staging detected bone metastasis and metastatic inguinal lymph nodes (M1a) that were undepicted on CT in 2 patients (3%), clearly defined 19 equivocal lesions on ceCT in 18 patients (31%) and excluded 6 metastatic lesions diagnosed by ceCT in 6 patients (10%). These resulted in alteration of management plan in 15 out of the 58 cases (26%) i.e. changing from chemotherapy to surgery (4), changing extent of surgery (9) and avoidance of futile surgery (2). Forty four patients underwent surgery within 45 days after PET/CT. The diagnostic accuracy for N staging with PET/ceCT and ceCT alone was 66% and 48% with false positive rates of 24% (6/25) and 76% (19/25) and false negative rates of 47% (9/19) and 21% (4/19), respectively. All of the false negative lymph nodes from PET/ceCT were less than a centimeter in size and located in peri-lesional regions. The diagnostic accuracy for T staging was 82%. The sensitivity of the peri-lesional fat stranding sign in determining T3 stage was 94% and the specificity was 54%. Conclusions: Our study suggested promising roles of PET/ceCT in initial staging of colorectal cancer with better diagnostic accuracy facilitating management planning.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3569-3573
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• 2016

Purpose: The aim of this study was to compare C-11 choline and F-18 FDG PET/CT, gadoxetic-enhanced 3-T MRI and contrast-enhanced CT for diagnosis of hepatocellular carcinoma (HCC). Materials and Methods: Twelve chronic hepatitis B patients suspected of having HCC by abdominal ultrasonography received all diagnostic modalities performed within a one-week timeslot. PET/CT results were analyzed visually by two independent nuclear medicine physicians and quantitatively by tumor to background ratio (T/B). Nine patients then had histopathological confirmation. Results: Six patients had well differentiated HCC, while two and one patient(s) were noted with moderately and poorly differentiated HCC, respectively. All were detected by both CT and MRI with an average tumor size of $5.7{\pm}3.8cm$. Five patients had positive C-11 choline and F-18 FDG uptake. Of the remaining four patients, three with well differentiated HCC showed negative F-FDG uptake (one of which showed negative results by both tracers) and one patient with moderately differentiated HCC demonstrated no C-11 choline uptake despite intense F-18 FDG avidity. The overall HCC detection rates with C-11 choline and F-18 FDG were 78% and 67%, respectively, while the sensitivity of F-18 FDG for non-well differentiated HCC was 100%, compared with 83% of C-11 choline. The average T/B of C-11 choline in well-differentiated HCC patients was higher than in moderately and poorly differentiated cases (p=0.5) and vice versa with statistical significance for T/B of F-18 FDG (p = 0.02). Conclusions: Our results suggested better detection rate in C-11 choline for well differentiated HCC than F-18 FDG PET. However, the overall detection rate of PET/CT with both tracers could not compare with contrast-enhanced CT and MRI.

• 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 Gastric Cancer
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• v.8 no.4
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• pp.250-255
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• 2008

Purpose: The purpose of this study was to assess the diagnostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for detecting the lymph node (LN) metastasis of gastric cancer. Materials and Methods: 119 patients (M : F=89 : 30; mean age: 64) with gastric cancer were referred for preoperative FDG-PET/CT scanning and spiral enhanced abdominal pelvic CT from June 2006 to July 2008, and these were the subjects of our study. All the patients underwent curative radical gastrectomy and lymph node dissection. A final diagnosis was made for all the patients by the histology of the surgical specimens. Results: Both PET/CT and enhanced CT showed similar sensitivity for detecting regional lymph node metastasis (32.6% vs 39.5%, respectively). PET/CT was more accurate than enhanced CT for detecting regional lymph node metastasis (67.2% vs 63.0%, respectively), and PET/CT showed better specificity (86.8% vs 76.3, respectively) and a better positive predictive value (PPV) (58.3% vs 48.6%, respectively). PET/CT showed better specificity (98.0% vs 88.2%, respectively) and accuracy (79.4% vs 73.9%, respectively) than enhanced CT for detecting early gastric cancer. PET/CT showed better specificity (64.0% vs 52.0%, respectively), a better PPV (60.9% vs 57.1%), a better negative predictive value (NPV) (48.5% vs 46.4%, respectively) and better accuracy (53.6% vs 51.8%, respectively) than enhanced CT for detecting advanced gastric cancer. Conclusion: FDG-PET/CT is more usefulness than enhanced CT for making the preoperative diagnosis of regional LN metastases from gastric cancers.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.3
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• pp.235-240
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• 2008

Purpose: At the beginning of PET/CT, Computed Tomography was mainly used only for Attenuation Correction (AC), but as the performance of the CT have been increase, it could give improved diagnostic information with Contrast Media. But it was controversial that Contrast Media could affect AC on PET/CT scan. Some submitted thesis' show that Contrast Media could overestimate when it is for AC data processing. On the contrary, the opinion that Contrast Media could be possible to affect the alteration of SUV because of the overestimated AC. But it does not have a definite effect on the diagnosis. Thus, the affection of Contrast Media on AC was investigated in this study. Materials and Methods: Patient inclusion criteria required a history of a malignancy and performance of an integrated PET/CT scan and contrast- enhanced CT scan within a 1-day period. Thirty oncologic patients who had PET/CT scan from December 2007 to June 2008 underwent staging evaluation and met these criteria. All patients fasted for at least 6 hr before the IV injection of approximately 5.6 MBq/kg (0.15 mCi/kg) of $^{18}F$-FDG and were scanned about 60 min after injection. All patients had a whole body PET/CT performed without IV contrast media followed by a contrast-enhanced CT on the Discovery STe PET/CT scanner. CT data were used for AC and PET images came out after AC. The ROIs drew and measured SUV. A paired t-test of these results was performed to assess the significance of the difference between the SUV obtained from the two attenuation corrected PET images. Results: The mean and maximum Standardized Uptake Values (SUV) for different regions averaged over all Patients. Comparing before using Contrast Media and after using, Most of ROIs have the increased SUV when it did Contrast Enhanced CT compare to Non-Contrast enhanced CT. All regions have increased SUV and also their p value was under 0.05 except the mean SUV of the Heart region. Conclusion: In this regard, the effect on SUV measurements that occurs when a contrast-enhanced CT is used for attenuation correction could have significant clinical ramifications. But some submitted thesis insisted that the percentage change in SUV that can determine or modify clinical management of oncology patients is small. Because there was not much difference that could be discovered by interpreter. But obviously the numerical change was occurred and on the stage finding primary region, small change would be base line, such as the region of liver which has greater change than the other regions needs more attention.

• Korean Journal of Radiology
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• v.25 no.3
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• pp.257-266
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• 2024

Objective: To investigate molecular and functional consequences of additional exposures to iodine- or gadolinium-based contrast agents within 24 hours from the initial intravenous administration of iodine-based contrast agents through an animal study. Materials and Methods: Fifty-six Sprague-Dawley male rats were equally divided into eight groups: negative control, positive control (PC) with single-dose administration of CT contrast agent, and additional administration of either CT or MR contrast agents 2, 4, or 24 hours from initial CT contrast agent injection. A 12 µL/g of iodinated contrast agent or a 0.47 µL/g of gadolinium-based contrast agent were injected into the tail vein. Serum levels of blood urea nitrogen, creatinine, cystatin C (Cys C), and malondialdehyde (MDA) were measured. mRNA and protein levels of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated. Results: Levels of serum creatinine (SCr) were significantly higher in repeated CT contrast agent injection groups than in PC (0.21 ± 0.02 mg/dL for PC; 0.40 ± 0.02, 0.34 ± 0.03, and 0.41 ± 0.10 mg/dL for 2-, 4-, and 24-hour interval groups, respectively; P < 0.001). There was no significant difference in the average Cys C and MDA levels between PC and repeated CT contrast agent injection groups (Cys C, P = 0.256-0.362; MDA, P > 0.99). Additional doses of MR contrast agent did not make significant changes compared to PC in SCr (P > 0.99), Cys C (P = 0.262), and MDA (P = 0.139-0.771) levels. mRNA and protein levels of KIM-1 and NGAL were not significantly different among additional CT or MR contrast agent groups (P > 0.05). Conclusion: A sufficient time interval, probably more than 24 hours, between repeated contrast-enhanced CT examinations may be necessary to avoid deterioration in renal function. However, conducting contrast-enhanced MRI on the same day as contrast-enhanced CT may not induce clinically significant kidney injury.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.18
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• pp.7719-7724
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• 2014

Background: Lymph node metastasis is believed to be a dependent negative prognostic factor of esophageal cancer. To explore detection methods with high sensitivity and accuracy for metastases to regional and distant lymph nodes in the clinic is of great significance. This study focused on clinical application of FDG PET/CT and contrast-enhanced multiple-slice helical computed tomography (MSCT) in lymph node staging of esophageal cancer. Materials and Methods: One hundred and fifteen cases were examined with enhanced 64-slice-MSCT scan, and FDG PET/CT imaging was conducted for neck, chest and upper abdomen within one week. The primary lesion, location and numbers of metastatic lymph nodes were observed. Surgery was performed within one week after FDG PET/CT detection. All resected lesions were confirmed histopathologically as the gold standard. Comparative analysis of the sensitivity, specificity, and accuracy based on FDG PET/CT and MSCT was conducted. Results: There were 946 lymph node groups resected during surgery from 115 patients, and 221 were confirmed to have metastasis pathologically. The sensitivity, specificity, accuracy of FDG PET/CT in detecting lymph node metastasis were 74.7%, 97.2% and 92.0%, while with MSCT they were 64.7%, 96.4%, and 89.0%, respectively. A significance difference was observed in sensitivity (p=0.030), but not the others (p>0.05). The accuracy of FDG PET/CT in detecting regional lymph node with or without metastasis were 91.9%, as compared to 89.4% for MSCT, while FDG PET/CT and MSCT values for detecting distant lymph node with or without metastasis were 94.4% and 94.7%. No significant difference was observed for either regional or distant lymph node metastasis. Additionally, for detecting para-esophageal lymph nodes metastasis, the sensitivity of FDG PET/CT was 72%, compared with 54.7% for MSCT (p=0.029). Conclusions: FDG PET/CT is more sensitive than MSCT in detecting lymph node metastasis, especially for para-esophageal lymph nodes in esophageal cancer cases, although no significant difference was observed between FDG PET/CT and MSCT in detecting both regional and distant lymph node metastasis. However, enhanced MSCT was found to be of great value in distinguishing false negative metastatic lymph nodes from FDG PET/CT. The combination of FDG PET/CT with MSCT should improve the accuracy in lymph node metastasis staging of esophageal cancer.