6 results on '"Koji Takumi"'
Search Results
2. Computed diffusion-weighted MR imaging for visualization of pancreatic adenocarcinoma: Comparison with acquired diffusion-weighted imaging
- Author
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Yoshihiko Fukukura, Takashi Yoshiura, Yuichi Kumagae, Toshikazu Shindo, Koji Takumi, Kiyoshisa Kamimura, Aya Umanodan, Hiroto Hakamada, and Masanori Nakajo
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Adult ,Male ,medicine.medical_specialty ,Adenocarcinoma ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Diffusion-Weighted MR Imaging ,Pancreas ,Aged ,Retrospective Studies ,Aged, 80 and over ,medicine.diagnostic_test ,business.industry ,Significant difference ,Magnetic resonance imaging ,General Medicine ,Middle Aged ,medicine.disease ,Hyperintensity ,Pancreatic Neoplasms ,Lower incidence ,Diffusion Magnetic Resonance Imaging ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Feasibility Studies ,Female ,Radiology ,Nuclear medicine ,business ,Diffusion MRI - Abstract
Objective To assess the feasibility of computed diffusion-weighted imaging (cDWI) in comparison with directly acquired DWI for visualizing pancreatic adenocarcinomas. Materials and methods Patients with pancreatic adenocarcinoma underwent DWI at b-values of 0, 1000 (DWI1000), 1500 (DWI1500) and 2000 (DWI2000) s/mm2. From DWIs at b-values of 0 and 1000 s/mm2, we generated cDWIs at b-values of 1500 (cDWI1500) and 2000 (cDWI2000) s/mm2. DWI findings of pancreatic adenocarcinomas (clear hyperintensity; hyperintensity with an unclear distal border; and isointensity), the image quality and the tumor to pancreas contrast ratio (CR) were compared between directly acquired DWI and cDWI. Results Among the 63 included patients, clear hyperintense tumors were seen in 35 on DWI1000, 50 on DWI1500, 50 on cDWI1500, 53 on DWI2000 and 44 on cDWI2000. Incidence of clear hyperintense tumors was significantly higher on cDWI1500 than on DWI1000 (P = 0.013). There was no significant difference in the incidence of clear hyperintense tumors between DWI1500 and cDWI1500 (P > 0.999), but a lower incidence was seen on cDWI2000 than on DWI2000 (P = 0.028). Image quality was lower on cDWI than on DWI at b-values of 1500 (P = 0.002) and 2000 s/mm2 (P Conclusions cDWI1500 generated from b-values of 0 and 1000 s/mm2 should be considered more effective than DWI1000 and at least as effective as DWI1500.
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- 2017
3. Value of diffusion tensor imaging in differentiating malignant from benign parotid gland tumors
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Yoshihiko Fukukura, Hiroto Hakamada, Junichi Ideue, Koji Takumi, Yuichi Kumagae, and Takashi Yoshiura
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Adult ,Male ,Pathology ,medicine.medical_specialty ,Sensitivity and Specificity ,Statistics, Nonparametric ,030218 nuclear medicine & medical imaging ,Diagnosis, Differential ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Fractional anisotropy ,medicine ,Humans ,Parotid Gland ,Effective diffusion coefficient ,Radiology, Nuclear Medicine and imaging ,Aged ,Aged, 80 and over ,medicine.diagnostic_test ,business.industry ,Significant difference ,Curve analysis ,Reproducibility of Results ,Magnetic resonance imaging ,General Medicine ,Middle Aged ,Parotid Neoplasms ,Parotid gland ,Diffusion Magnetic Resonance Imaging ,Diffusion Tensor Imaging ,medicine.anatomical_structure ,ROC Curve ,Mann–Whitney U test ,Female ,business ,Nuclear medicine ,030217 neurology & neurosurgery ,Diffusion MRI - Abstract
Purpose To evaluate whether diffusion tensor imaging (DTI) can be used to differentiate malignant parotid gland tumors from the benign ones. Materials and methods The study population comprised 59 parotid gland tumors (24 Warthin’s tumors, 19 pleomorphic adenomas, seven other benign tumors, and nine malignant tumors). Single-shot echo-planar DTI was performed with motion-probing gradients along 30 noncollinear directions (b = 1000 s/mm2) at 3.0 T. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values for benign and malignant tumors were compared using the Mann–Whitney U test. Receiver-operating characteristic (ROC) curve analysis was performed to assess the ability of the ADC and FA values to differentiate malignant tumors from the benign ones. Results ADC values showed no significant difference between malignant (0.93 ± 0.21 × 10−3 mm2/s) and benign tumors (1.19 ± 0.50 × 10−3 mm2/s) (p = 0.225). FA values of malignant tumors were significantly higher than those of benign tumors (0.26 ± 0.06 vs. 0.17 ± 0.05, p Conclusions DTI, particularly FA, can help differentiate malignant parotid gland tumors from the benign ones.
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- 2017
4. Risk assessment of osteoradionecrosis associated with periodontitis using 18F-FDG PET/CT
- Author
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Noriyuki Fujima, Muhammad M. Qureshi, Takashi Kaneda, Kotaro Ito, Andrew R. Salama, Sara K. Meibom, V. Carlota Andreu-Arasa, Minh Tam Truong, Osamu Sakai, and Koji Takumi
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Periodontitis ,business.industry ,Osteoradionecrosis ,medicine.medical_treatment ,Standardized uptake value ,General Medicine ,Periodontology ,medicine.disease ,030218 nuclear medicine & medical imaging ,Radiation therapy ,03 medical and health sciences ,0302 clinical medicine ,030220 oncology & carcinogenesis ,medicine ,Radiology, Nuclear Medicine and imaging ,Periodontal region ,Oral Cavity Squamous Cell Carcinoma ,Nuclear medicine ,business ,Complication - Abstract
Purpose Osteoradionecrosis (ORN) is a serious complication after radiotherapy (RT), even in the era of intensity modulated radiation therapy (IMRT). The purpose of this study was to evaluate whether 18F-FDG PET/CT can predict ORN associated with periodontal disease in patients with oropharyngeal or oral cavity squamous cell carcinoma (OP/OC SCC) undergoing RT. Methods One hundred and five OP/OC SCC patients treated with RT who underwent pretreatment 18F-FDG PET/CT between October 2007 and June 2016 were retrospectively reviewed. A post-treatment diagnosis of ORN was made clinically based on presence of exposed irradiated mandibular bone that failed to heal after a period of three months without persistent or recurrent tumor. The maximum standardized uptake value (SUVmax) of periodontal regions identified on PET/CT was measured for all patients. Image-based staging of periodontitis was also performed using American Academy of Periodontology staging system on CT. Results Among 105 patients, 14 (13.3 %) developed ORN. The SUVmax of the periodontal region in patients with ORN (3.35 ± 1.23) was significantly higher than patients without ORN (1.92 ± 0.66) (P Conclusions Pretreatment 18F-FDG PET/CT identification of periodontitis may be helpful to predict the future development of ORN in patients with OP/OC SCC undergoing RT.
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- 2020
5. Using CT texture analysis to differentiate cystic and cystic-appearing odontogenic lesions
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V. Carlota Andreu-Arasa, Margaret N. Chapman, Albert Wang, Pedro V. Staziaki, Osamu Sakai, Baojun Li, Koji Takumi, Masafumi Oda, Muhammad M. Qureshi, and Andrew R. Salama
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Adult ,Male ,medicine.medical_specialty ,Adolescent ,Dentigerous Cyst ,Texture (geology) ,030218 nuclear medicine & medical imaging ,Ameloblastoma ,Diagnosis, Differential ,Lesion ,Young Adult ,03 medical and health sciences ,Tooth root ,0302 clinical medicine ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Statistical analysis ,Child ,Aged ,Retrospective Studies ,Aged, 80 and over ,business.industry ,General Medicine ,Middle Aged ,Jaw Neoplasms ,Odontogenic ,Feature (computer vision) ,030220 oncology & carcinogenesis ,Odontogenic Cysts ,Female ,Radiology ,Ct imaging ,medicine.symptom ,Tomography, X-Ray Computed ,business - Abstract
Purpose Cystic and cystic-appearing odontogenic lesions of the jaw may appear similar on CT imaging. Accurate diagnosis is often difficult although the relationship of the lesion to the tooth root or crown may offer a clue to the etiology. The purpose of this study was to evaluate CT texture analysis as an aid in differentiating cystic and cystic-appearing odontogenic lesions of the jaw. Methods This was an IRB-approved retrospective study including 42 pathology-proven dentigerous cysts, 37 odontogenic keratocysts, and 19 ameloblastomas. Each lesion was manually segmented on axial CT images, and textural features were analyzed using an in-house-developed Matlab-based texture analysis program that extracted 47 texture features from each segmented volume. Statistical analysis was performed comparing all pairs of the three types of lesions. Results Pairwise analysis revealed that nine histogram features, one GLCM feature, three GLRL features, two Laws features, four GLGM features and two Chi-square features showed significant differences between dentigerous cysts and odontogenic keratocysts. Four histogram features and one Chi-square feature showed significant differences between odontogenic keratocysts and ameloblastomas. Two histogram features showed significant differences between dentigerous cysts and ameloblastomas. Conclusions CT texture analysis may be useful as a noninvasive method to obtain additional quantitative information to differentiate cystic and cystic-appearing odontogenic lesions of the jaw.
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- 2019
6. Feasibility of a fixed scan delay technique using a previous bolus tracking technique data for dynamic hepatic CT
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Takuro Kamiyama, Masayuki Nakajo, Toshikazu Shindo, Koji Takumi, Akihiro Tateyama, Yuichi Kumagae, and Yoshihiko Fukukura
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Male ,medicine.medical_specialty ,Carcinoma, Hepatocellular ,Contrast enhancement ,Contrast Media ,Sensitivity and Specificity ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Bolus tracking ,business.industry ,Liver Neoplasms ,Significant difference ,Reproducibility of Results ,General Medicine ,Radiographic Image Enhancement ,Contrast medium ,Feasibility Studies ,Radiographic Image Interpretation, Computer-Assisted ,Female ,Radiology ,Tomography, X-Ray Computed ,Nuclear medicine ,business ,Algorithms ,Iodine ,Arterial phase - Abstract
Objective To compare the quality of contrast enhancement and hepatic CT images acquired using bolus tracking technique at two different time points and those acquired with fixed scan delay technique using a previous bolus tracking data. Materials and methods Fifty patients who underwent 3 different hepatic CT exams (25-s fixed injection of 600 mg iodine (I)/kg or 100 mL of 370 mg I/mL nonionic contrast medium) were enrolled. The first and second exams were performed with a bolus tracking technique. The third exam was performed with a fixed scan delay technique using the first exam data. Differences in attenuation values in the abdominal organs were examined and evaluated visually on hepatic arterial phase images. Results There was no significant difference in the mean 50-HU threshold times between the first and second bolus tracking exams with intra-patient differences between them (1.3 ± 0.9 s). No significant intra-patient differences were noted in organ attenuation and visual evaluation on hepatic arterial phase images between the 3 exams. Conclusion The fixed scan delay technique using a previous bolus tracking data is feasible for hepatic CT exams to follow up hepatocellular carcinoma.
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- 2012
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