Radiation medicine最新文献

Purpose: The aim of this study was to optimize a novel adaptive noise reduction filter based on patient body weight and to investigate its utility for improving the image quality of low-dose hepatic computed tomography (CT) scans.

Materials and methods: The tube current-time product was changed from 140 to 180 and from 60 to 100 mAs at standard- and low-dose CT, respectively, based on the body weights of 45 patients. Unenhanced and two-phase contrast-enhanced helical scans were obtained at the standard dose during the hepatic arterial and equilibrium phases. During the equilibrium phase, we obtained low-dose scans of the liver immediately after standard-dose scans. The low-dose CT images were postprocessed with the filter. Two radiologists visually evaluated artifacts in the liver parenchyma and its graininess, the sharpness of the liver contour, tumor conspicuity, homogeneity of the enhancement of the portal vein, and overall image quality.

Results: There was no statistically significant difference between standard and filtered low-dose images with respect to artifacts in the liver, the graininess of the liver parenchyma, tumor conspicuity, homogeneity of enhancement of the portal vein, or overall image quality.

Conclusion: The adaptive noise reduction filter effectively reduced image noise. We confirmed the effectiveness of the filter by examining clinical hepatic images obtained at low-dose CT.

Purpose: The aim of this study was to ascertain whether diffusion tensor imaging (DTI) metrics fractional anisotropy (FA), mean diffusivity (MD), linear case (CL), planar case (CP), spherical case (CS)-can characterize a threshold dose and temporal evolution of changes in normal-appearing white matter (NAWM) of adults with low-grade gliomas (LGGs) treated with radiation therapy (RT).

Methods and materials: Conventional and DTI imaging were performed before RT in 5 patients and subsequently, on average, at 3 months (n = 5), 8 months (n = 3), and 14 months (n = 5) following RT for a total of 18 examinations. Isodose distribution at 5-Gy intervals were visualized in all the slices of fluid attenuated inversion recovery (FLAIR) and the corresponding DTI images without diffusion sensitization (b0DTI). The latter were exported for relative quantitative analysis.

Results: Compared to pre-RT values, FA and CL decreased, whereas CS increased at 3 and 8 months and recovered partially at 14 months for the dose bins >55 Gy and 50-55 Gy. For the 45 50 Gy bin, the FA and CL decreased with an increase in CS at 3 months; no further change was seen at 8 or 14 months. For the >55 Gy and 50-55 Gy bins, CP decreased and MD increased at 3 months and returned to baseline at 8 months following RT.

Conclusion: Radiation-induced changes in NAWM can be detected at 3 months after RT, with changes in FA, CL, and CS (but not CP or MD) values seen at a threshold dose of 45-50 Gy. A partial recovery was evident by 14 months to regions that received doses of 50-55 Gy and >55 Gy, thus providing an objective measure of radiation effect on NAWM.

Phlebosclerotic colitis (PC) is a rare form of ischemic colitis that usually affects the right hemicolon. It is due to ischemia induced by phlebosclerosis in the branches of the superior mesenteric vein that disturb venous return from the colon. The clinical course is different from that of the more common type of ischemic colitis caused by arterial disease. We encountered a 73-year-old woman with PC who had the characteristic computed tomographic finding of fine linear venous calcification that was mainly perpendicular to the long axis of the colon.

Purpose: Motion artifact is problematic in the diagnosis of Creutzfeldt-Jakob disease (CJD) because of dementia. The purpose was to compare the occurrence of this artifact between a diffusion-weighted (DW) magnetic resonance (MR) imaging sequence and conventional sequences.

Materials and methods: Ten MR examinations comprising T2-weighted, T1-weighted, DW, and fluid-attenuated inversion recovery imaging in seven CJD patients were retrospectively evaluated. The occurrence of motion artifacts on each sequence were assessed, and the examination was classified into four groups as follows: group A, motion artifact not revealed on DW imaging but revealed on one or more other sequences; group B, revealed on DW imaging and one or more other sequences; group C, not revealed on any sequences; and group D, revealed on DW imaging but not on any other sequences.

Results: The 10 MR examinations were classified as eight group A (80%), one B (10%), one C (10%), and zero D (0%).

Conclusion: Motion artifacts are likely to occur in any conventional imaging sequences in CJD, but the fast-imaging ability of DW imaging can reduce this artifact. The combination of an absence of motion artifact on DW imaging and the presence on conventional sequences may be one of the frequent findings of CJD.

Purpose: The aim of this study was to evaluate the diameters of the various bony canals of the inner ear in patients with sensorineural hearing loss (SNHL) and establish criteria for detecting hypoplasia of the bony canal of the cochlear nerve.

Materials and methods: Measurements obtained in 118 patients without inner ear malformations among 160 patients with unilateral SNHL were analyzed. The diameters of the internal auditory canal and the bony canals of the cochlear, vestibular, and facial nerves were measured on transverse or coronal computed tomographic images. Mean values (+/- SD) were compared between the affected and unaffected ears, and statistical analysis was done.

Results: The diameter of the bony canal of the cochlear nerve was significantly smaller in affected ears than in unaffected ears (P < 0.01). The affected ears could be divided into groups with (72 ears) and without (46 ears) bony canal stenosis.

Conclusions: Most (60%) of the patients with unilateral SNHL showed a significant difference in the diameters of the bony canals of the cochlear nerve between the affected and unaffected sides; moreover, the mean value was significantly smaller in affected ears. The diameter of < 1.7 mm on transverse images or < 1.8 mm on coronal images suggests hypoplasia.

Nonpuerperal traumatic vulvar hematomas are relatively uncommon. Conservative and surgical management are the usual treatment options for traumatic vulvar hematomas. There is no report of transarterial embolization of nonpuerperal traumatic vulvar hematoma. We report a 35-year-old woman who presented with a vulvar hematoma caused by an accidental fall on a toy of her child. The hematoma was expanding and was refractory to conservative treatment. A computed tomography (CT) scan revealed active extravasation of contrast material from the left internal pudendal artery. We performed transarterial embolization of the left internal pudendal artery. The left external pudendal artery, which had an anastomosis with the left internal pudendal artery, was also embolized. Postembolization angiography demonstrated no further extravasation of contrast material. We believe that transarterial embolization can be an effective treatment of nonpuerperal traumatic vulvar hematomas when conservative treatment fails.

Purpose: The purpose of this study was to assess radiographic and computed tomography (CT) findings of the vertical fissure.

Materials and methods: We assessed whether the vertical fissures appeared as a fine linear shadow or as a linear edge with lateral opacity and medial lucency on chest radiographs. The CT scans were evaluated for the presence of volume loss in the lower lobes and for the presence of a portion of the fissure that is orientated tangential to the X-ray beam.

Results: We observed vertical fissures in six patients. CT studies revealed volume loss in the lower lobes in all patients and showed the presence of a portion of the fissure that is orientated tangential to the X-ray beam in only two patients whose vertical fissures were not associated with lateral opacity and medial lucency on chest radiographs.

Conclusion: We believe that the vertical fissure is closely related to volume loss in the lower lobe and represents the edge of the anterobasal segment of a major fissure or a portion of the fissure that is orientated tangential to the X-ray beam, with or without lateral opacity and medial lucency.

Purpose: The aim of this study was to create an adaptive computed tomography dose index (by volume) (CTDI vol) for pediatric patients that would be fitted to a patient's particular body weight and to compare the adaptive CTDI vol with the CTDI vol displayed on the screen of the CT console.

Materials and methods: CT images of 60 children whose body weights were known were available for calculating the total amount of modified CT numbers as an attenuation area. The attenuation area values of four differentsized acryl phantoms were also calculated. The dose measurements of all four phantoms were carried out. We combined the results of the abdominal CT and phantom experiments. The weight-based complementary ratio for adaptive CTDI vol was calculated, and the result was applied to an example of pediatric abdominal CT protocol.

Results: The adaptive CTDI vol was always larger than the displayed CTDI vol with both small and large fields of view (FOV). The adaptive CTDI vol was 2.2 times larger than the displayed CTDI vol in the maximum value with the large FOV and 1.2 times larger with the small FOV.

Conclusion: We radiologists must be the child's advocate and protect children from the deleterious effects of any of our technologies, including a lower indication of CTDI vol on the screen of a CT console.

Purpose: The aim of our study was to evaluate the usefulness of percutaneous radiofrequency ablation (RFA) using CO2 microbubbles-enhanced sonography for patients with local tumor progression of hepatocellular carcinoma (HCC).

Materials and methods: The tumors of 14 patients with local progression of HCC were treated with CO2 microbubbles-enhanced RFA ablation via a catheter that had been placed in the hepatic artery. We assessed tumor detectability and technical effectiveness. The mean follow-up period was 14.1 months.

Results: Only 6 of the tumors could be found on conventional sonography, whereas 14 tumors were detected on CO2 microbubbles-enhanced sonography. These 14 lesions were successfully treated with RFA guided by CO2 microbubbles-guided sonography. Technical effectiveness was complete in all patients. No serious complications were observed, and there was no local tumor progression during the follow-up period.

Conclusion: RFA guided by CO2 microbubbles-guided sonography is a feasible technique for treating local progression of HCC lesions that cannot be adequately depicted by conventional sonography.