Biomedical subjects

Kuni Ohtomo

Publications and source records attributed to Kuni Ohtomo.

At least 19 recordsLinked to original sources

PubMed2006

A retrospective study of radiotherapy for spinal bone metastases from hepatocellular carcinoma (HCC).

OBJECTIVE: To evaluate the therapeutic effects of radiotherapy on spinal bone metastases from hepatocellular carcinoma (HCC). METHODS: A retrospective review was conducted on 24 ambulatory patients with spinal bone metastases from HCC treated by radiotherapy from 1995 to 2004. Ambulatory rate and local progression-free rate after radiotherapy were analyzed. Eight (33%) of 24 patients had radiographic spinal cord compression from the spinal bone metastases before the treatment. Two (8.3%) of the 24 patients had some spinal deficits before the treatment. Biological equivalent dose (BED) with alpha/beta ratios of 10 ranged from 39 to 50.7 Gy (median 44.8 Gy). RESULTS: The median observation period was 5.1 months ranging from 0.9 to 36.0 months. Among the 24 patients, five (21%) underwent salvage therapies, while of the remaining 19 patients four (21%) became nonambulatory by the last follow-up. The ambulatory rates at 3 months and 6 months were 85 and 63%, respectively. The local progression-free rates at 3 months and 6 months were 53 and 47%, respectively. CONCLUSIONS: Radiotherapy with a BED of 39-50.7 Gy (median 44.8 Gy) is not sufficiently effective for the patients with spinal bone metastases from HCC to prevent paralysis. Dose escalation with a highly precise radiation technique will need to be evaluated.

Aged↗

PubMed2006

Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner.

PURPOSE: The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms. MATERIALS AND METHODS: Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation. RESULTS: We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful. CONCLUSION: The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections.

Anisotropy↗

PubMed2006

Relation between acute and late irradiation impairment of four basic tastes and irradiated tongue volume in patients with head-and-neck cancer.

PURPOSE: Taste loss is a major cause of morbidity in patients undergoing head-and-neck irradiation. The relationship between the time course and the degree of taste disorder was studied in both acute and late phases. METHODS AND MATERIALS: Taste ability was measured by the taste threshold for the four basic tastes using a filter paper disc method in patients before, during, and after radiotherapy. The subjects were divided into two groups. In Group A, the radiation fields included most of the tongue (n = 100), and in Group B the radiation fields did not include the tip of the tongue (n = 18). RESULTS: In Group A, there was a significant impairment of the threshold of all four basic tastes at 3 weeks after starting radiotherapy (RT), and this impairment remained at 8 weeks (p < 0.05). This was not seen in Group B. In Group A, there was no significant difference in the patterns of taste sensitivity change between the high-dose (>20 Gy) and low-dose (< or =20 Gy) groups. In the late phase, recovery of taste loss was seen in both groups since 4 months after completing RT. CONCLUSIONS: Unless the anterior part of the tongue was irradiated, taste loss was not observed during RT. When the anterior part of the tongue was irradiated, a difference by radiation dose was not observed in the taste loss pattern. Additionally, radiation-induced taste dysfunction appears to be a temporal effect.

Adult↗

PubMed2006

Evaluation of left ventricular function with cardiac magnetic resonance imaging using Fourier fitting.

The aims of this study were to investigate the applicability of Fourier fitting in the magnetic resonance (MR) evaluation of left ventricular (LV) function and to determine the optimal number of harmonics for fitting. Cine cardiac MR imaging was performed in 10 subjects, and an LV time-volume curve was generated. Fourier fitting was applied to the original curve using 1-10 harmonics, and the qualities of the time-volume curve and first-derivative curve were evaluated. LV functional parameters were calculated from curves generated with and without fitting. The quality of the original time-volume curve was good, and Fourier fitting had no substantial effect on functional parameters obtained directly from the time-volume curve such as ejection fraction. The first-derivative curve generated without fitting showed substantial artificial fluctuation. The application of Fourier fitting depressed the fluctuation and tended to decrease estimates of peak ejection rate and peak filling rate. Five or six harmonics appeared to be appropriate for obtaining a high-quality first-derivative curve. In conclusion, Fourier fitting was indicated to aid in reducing the artificial fluctuation of the first-derivative curve generated from cine cardiac MR imaging and to contribute to the evaluation of functional parameters derived from the first-derivative curve.

Adult↗

PubMed2006

Aging in the CNS: comparison of gray/white matter volume and diffusion tensor data.

This study investigated the global and regional effects of aging on brain volume, mean diffusivity (MD), and fractional anisotropy (FA) in 73 normal female subjects using voxel-based analysis. On a global scale, gray matter volume and FA were negatively correlated, whereas MD was positively correlated with age. Voxel-wise analyses showed brain volume and FA were negatively correlated predominantly in anterior structures, whereas MD was positively correlated in the cortical gray matter and periventricular white matter. Volume preservation was observed in the cingulate gyrus and subjacent white matter. FA increase was observed in the putamen. Voxel-based direct comparisons of volume and diffusion properties showed FA was more strongly negatively correlated in the fronto-temporal white matter, compared with volume and MD. Stronger positive correlation of MD was observed in the thalamus, caudate nucleus, and midbrain and stronger negative correlation of brain volume was observed in the frontal lobe and basal ganglia, compared with the other. These results indicate that diffusion properties and brain volume are complementary markers to the effects of aging.

Adult↗

PubMed2006

[Utility of axial images in an early Alzheimer disease diagnosis support system (VSRAD)].

In recent years, voxel-based morphometry (VBM) has become a popular tool for the early diagnosis of Alzheimer disease. The Voxel-Based Specific Regional Analysis System for Alzheimer's Disease (VSRAD), a VBM system that uses MRI, has been reported to be clinically useful. The able-bodied person database (DB) of VSRAD, which employs sagittal plane imaging, is not suitable for analysis by axial plane imaging. However, axial plane imaging is useful for avoiding motion artifacts from the eyeball. Therefore, we created an able-bodied person DB by axial plane imaging and examined its utility. We also analyzed groups of able-bodied persons and persons with dementia by axial plane imaging and reviewed the validity. After using the DB of axial plane imaging, the Z-score of the intrahippocampal region improved by 8 in 13 instances. In all brains, the Z-score improved by 13 in all instances.

Alzheimer Disease↗

PubMed2006

[Examination of an imaging method in early Alzheimer disease diagnosis support system (VSRAD)].

The use of voxel-based morphometry (VBM) has recently become a popular tool for the early diagnosis of Alzheimer disease. The Voxel-Based Specific Regional Analysis System for Alzheimer's Disease (VSRAD) is a clinically useful VBM that employs MRI. However, there has been insufficient information about the influence of the image pickup apparatus and imaging conditions in terms of the value calculated by the sensitivity correction. We therefore reviewed this problem in a volunteer who provided consent. We were able to confirm reproducibility under the same conditions. When changing the image pickup apparatus and conditions, the average Z-score of 0.18+/-0.21 became larger, and the change in Z-score increased when imaging was done in the axial plane. Further, the average Z-score of 0.06+/-0.21 for sensitivity correction use was high on average by 0.19+/-0.16 for phased-array uniformity enhancement (PURE) and low for surface coil intensity correction (SCIC).

Adult↗

PubMed2006

Radiophotoluminescence dosimetry using a small spherical glass: a preliminary phantom study.

A radiophotoluminescence dosimetry has been proposed using a spherical silver-activated phosphate glass with a diameter of 1.5 mm. A 6 MV photon dose of 2 Sv (2 Gy) was delivered to 14 spherical glass samples placed between two solid water phantoms at a depth of 10 cm. The samples were positioned within a 20 x 20 mm(2) centred at beam axis to ensure uniform dose absorption. A normalised output from a read-out system was obtained by simultaneously measuring luminescence from a non-irradiated reference and that from an irradiated reference to eliminate background contamination and time-varying fluctuation of the readout system, leading to a normalised standard deviation of 1.8%. A dose up to 3.5 Sv (3.5 Gy) was delivered to three spherical glass samples positioned between two solid water phantoms at a depth of 10 cm. The normalised output increased linearly with the applied dose.

Luminescent Measurements↗

PubMed2006

Treatment results of chemoradiation therapy for localized aggressive lymphomas: A retrospective 20-year study.

In this study we analyzed our cases of localized aggressive lymphoma treated in our institution during the last 20 years to compare the finding of this study with those of previous studies. Forty patients with Ann Arbor stage I-II aggressive lymphoma were treated with 3-6 cycles of a CHOP regimen (cyclophosphamide, doxorubicin, vincristine, and prednisolone) and radiation therapy (30 or 40 Gy with involved field). Between 1985 and 2003, 40 patients with stage I (N = 25) or stage II (N = 15) disease were treated. Chemotherapy mainly preceded radiotherapy, although the sequence of radiotherapy and chemotherapy was determined by individual physicians and patients' choice. Median and mean age was 50.5 and 48.6 years, respectively, at the time of diagnosis, with a male to female ratio of 19:21. Analyses were undertaken to determine (1) response to treatment according to age, international prognostic index (IPI), lactate dehydrogenase (LDH) value, serum interleukin 2 receptor (sIL-2R) value, cell type, stage, extent of maximum local disease, with or without mediastinal lymph nodes, number of sites, anatomic distribution, and irradiation dose, and (2) relapse patterns. Complete follow-up was obtained in all patients. The follow-up period of surviving 33 patients ranged from 24.7 to 180 months with a median of 69 and a mean of 72.7 months. A complete remission (CR) was achieved in 37 patients (93%). A study of relapse patterns after a CR showed that four patients had a first relapse within a radiation field and the other one patient had an extranodal distant relapse. Significant prognostic factors were not identified by multivariate analysis. Combined chemotherapy and radiation therapy is safe, highly effective, and probably curative for most patients with stage I-II aggressive lymphoma.

Adult↗

PubMed2006

Voxel-based diffusion tensor analysis reveals aberrant anterior cingulum integrity in posttraumatic stress disorder due to terrorism.

Recent functional neuroimaging work has suggested that interregional functional connectivity between the anterior cingulate cortex (ACC), other limbic, and prefrontal regions may be involved in the pathophysiology of posttraumatic stress disorder (PTSD). However, less attention has been paid to the white matter network. Voxel-based analysis enables an exploration of morphological or functional changes throughout the entire brain. Here we undertook the first application of this technology to diffusion tensor data in patients with PTSD. Participants were 9 victims of the Tokyo subway sarin attack with PTSD and 16 matched victims of the same traumatic event without PTSD. The voxel-based analysis showed a significant fractional anisotropy increase in the left anterior cingulum, subjacent to the left ACC gray matter where we previously found a volume decrement, in PTSD subjects. Moreover, the severity was positively, but not significantly associated with the fractional anisotropy of the left anterior cingulum in the victims with PTSD, using the region of interest defined in the native space with the inverse normalization technique. The present study demonstrated further evidence of abnormalities of both the ACC, a structure that is pivotally involved in attention, emotional regulation, and fear conditioning, and of subjacent white matter in the pathology of PTSD.

Adult↗

PubMed2006

Myocardial glucose utilisation in type II diabetes mellitus patients treated with sulphonylurea drugs.

PURPOSE: Chronic sulphonylurea treatment maintains improved glycaemic control through mechanisms other than enhancement of insulin secretion and may act on various organs. The aim of this study was to investigate whether the chronic use of sulphonylurea drugs influences PET measurement of myocardial glucose utilisation (MGU) in type II diabetes mellitus. METHODS: Forty-two patients with type II diabetes mellitus and 17 control subjects underwent dynamic (18)F-FDG PET to measure MGU during hyperinsulinaemic euglycaemic clamping. Twenty-one patients had been taking sulphonylurea drugs for more than 1 year (SU group), and the other 21 patients were drug naive (non-SU group). The haemoglobin A1c levels in the two patient groups were similar. Glucose disposal rate (GDR) was also determined as a marker of whole-body insulin resistance. RESULTS: GDR in the SU group (9.01+/-2.53 mg min(-1) kg(-1)) was significantly higher than that in the non-SU group (4.10+/-2.47, p<0.01) and was similar to that in the controls (9.76+/-2.97). MGU in the SU group (7.66+/-3.02 mg min(-1) 100 g(-1)) was significantly higher than that in the non-SU group (5.53+/-2.05, p<0.01) and was similar to that in the controls (7.49+/-2.74). CONCLUSION: Chronic sulphonylurea treatment influences MGU independent of the degree of glycaemic control. The effect of medication should be kept in mind when measuring and interpreting MGU in patients with type II diabetes mellitus.

Diabetes Mellitus, Type 2↗

PubMed2006

Liver CT image processing: a short introduction of the technical elements.

In this paper, we describe the technical aspects of image analysis for liver diagnosis and treatment, including the state-of-the-art of liver image analysis and its applications. After discussion on modalities for liver image analysis, various technical elements for liver image analysis such as registration, segmentation, modeling, and computer-assisted detection are covered with examples performed with clinical data sets. Perspective in the imaging technologies is also reviewed and discussed.

Humans↗

PubMed2006

Taste dysfunction in patients receiving radiotherapy.

BACKGROUND: Taste loss is a major cause of morbidity in patients undergoing head and neck irradiation. METHODS: In a prospective study, 51 patients undergoing radical head and neck irradiation at the Tokyo University Hospital were assessed for taste loss. Taste ability was measured by the taste threshold for the four basic tastes (sweet, sour, salt, and bitter qualities) plus another taste of "umami" quality using a filter-paper-disc method in patients before, during, and after radiotherapy (RT). RESULTS: All tastes declined on the fifth week after the start of RT and improved on the 11th week. Anatomic pathologic analyses in rats revealed that taste buds diminished completely on the sixth day after irradiation of 15 Gy in a single fraction, and the appearance of taste buds returned almost to the preirradiation state on the 28th day. CONCLUSIONS: The main cause of taste disorder resulting from RT was believed to be a disappearance of taste buds and not damage to the taste nerves.

Adult↗

PubMed2006

Imaging living mice using a 1-T compact MRI system.

PURPOSE: To determine the feasibility of imaging living mice with a 1-T compact MRI system and investigate appropriate imaging techniques for use in routine animal experiments. MATERIALS AND METHODS: An MRI system consisting of a 1-T permanent magnet and compact console was used. Images of the entire trunks of living mice were obtained on the system using a T1-weighted three-dimensional fast low-angle shot (3D FLASH) sequence, and image quality was evaluated in relation to imaging techniques. RESULTS: Restraint of respiratory motion improved the image quality. Decreasing the slice thickness reduced artificial inhomogeneity in signal intensity (SI). Substantial effects of TR and FA on image quality were also demonstrated. With the determined techniques, images covering the entire trunk with a voxel size of 0.26x0.26x0.52 mm were acquired in an acquisition time of five minutes 28 seconds and a total experiment time of <20 minutes, and various organs and subcutaneous tumors were clearly visualized. CONCLUSION: The compact MRI system provides images of living mice with acceptable quality in a reasonable time. Considering its convenience, it appears to be suitable for use in routine mouse experiments.

Animals↗

PubMed2006

Treatment planning and dosimetry of a multi-axis dynamic arc technique for prostate cancer: A comparison with IMRT.

PURPOSE: Intensity-modulated radiation therapy (IMRT) allows greater dose conformity to the tumor target. However, IMRT, especially static delivery, usually requires more time to deliver a dose fraction than conventional external beam radiotherapy (EBRT). The authors have been using a "two-axis dynamic arc therapy" (2A-DAT) technique for prostate cancer treatment to make a concave dose distribution to spare the rectum and bladder while working with limited time and human resources. The objectives of this study were to (1) clinically implement the 2A-DAT technique, (2) evaluate the dosimetry in comparison with IMRT, and (3) analyze the initial treatment outcome. MATERIALS AND METHODS: The 2A-DAT consists of two dynamic arc therapies (DATs) with half rotation around two isocenters each in two separate symmetrical rhombi. Treatment planning is forward and on a trial-and-error basis. Thirty-four patients received 2A-DAT with a median prescribed dose of 70 Gy. RESULTS: Although inferior in dose uniformity, the 2A-DAT provided equivalent sparing of normal structures to IMRT. Daily fraction delivery time for the 34 patients ranged from 6.4 to 9.6 minutes, with an average of 7.4 minutes. Five-year survival and five-year prostate specific autigen (PSA) failure-free survival were 89.3% and 79.5%, respectively. Three patients developed grade 2 proctitis. CONCLUSION: This technique is a possible alternative to IMRT in EBRT of prostate cancer.

Aged↗

PubMed2006

Treatment results of preoperative concurrent chemoradiotherapy followed by surgery for stage III or IV esophageal squamous cell carcinoma.

PURPOSE: To evaluate the treatment outcome of preoperative neoadjuvant radiotherapy combined with chemotherapy (CTx) for 17 esophageal cancer patients. MATERIALS AND METHODS: Between 1992 and 2004, patients with locally advanced esophageal cancer (stage III or IV) before curative-intent surgery received radiotherapy (RT) combined with CTx (Cisplatin: 75 mg/m2, bolus infusion, and 5-fluorouracil (5-FU): 1,000 mg/m2/24 h, continuous infusion for 4 days) at a median total dose of 30 Gy (n=17). RESULTS: The median survival period was 13.8 months. The overall survival rates at 1, 2, and 3 years were 75%, 40%, and 20%, respectively. According to univariate analysis, no factor of worse prognosis was found. Pathological markedly (Grade 3) or moderately (Grade 2) effects were observed in 4 patients (24%) and 8 patients (47%), respectively. CONCLUSION: These results indicate that, although this regimen was effective in terms of pathological effect, it is unclear whether it made a contribution to the improvement of survival

Aged↗

PubMed2006

Abnormal accumulation of [18F]fluorodeoxyglucose in the aortic wall related to inflammatory changes: three case reports.

We present 3 cases with abnormal accumulation of FDG in the aortic wall. Their clinical manifestations were vague or asymptomatic, and laboratory data were consistent with inflammatory reaction. These 3 patients were diagnosed with Takayasu arteritis, inflammatory aortic aneurysm (IAA), and retroperitoneal fibrosis (RF), respectively. FDG-PET and CT images showed the intense FDG uptake corresponding to the arterial walls and/or the soft tissue density surrounding the artery. It was deduced that FDG was probably taken up by inflammatory cells which infiltrated the arterial walls and/or the soft tissue mass. These cases indicated that FDG-PET is a useful method for localization of inflammatory lesion in patients with unspecific clinical findings and laboratory data.

Aorta↗

PubMed2006

In vitro validation of bioluminescent monitoring of disease progression and therapeutic response in leukaemia model animals.

PURPOSE: The application of in vivo bioluminescence imaging to non-invasive, quantitative monitoring of tumour models relies on a positive correlation between the intensity of bioluminescence and the tumour burden. We conducted cell culture studies to investigate the relationship between bioluminescent signal intensity and viable cell numbers in murine leukaemia model cells. METHODS: Interleukin-3 (IL-3)-dependent murine pro-B cell line Ba/F3 was transduced with firefly luciferase to generate cells expressing luciferase stably under the control of a retroviral long terminal repeat. The luciferase-expressing cells were transduced with p190 BCR-ABL to give factor-independent proliferation. The cells were cultured under various conditions, and bioluminescent signal intensity was compared with viable cell numbers and the cell cycle stage. RESULTS: The Ba/F3 cells showed autonomous growth as well as stable luciferase expression following transduction with both luciferase and p190 BCR-ABL, and in vivo bioluminescence imaging permitted external detection of these cells implanted into mice. The bioluminescence intensities tended to reflect cell proliferation and responses to imatinib in cell culture studies. However, the luminescence per viable cell was influenced by the IL-3 concentration in factor-dependent cells and by the stage of proliferation and imatinib concentration in factor-independent cells, thereby impairing the proportionality between viable cell number and bioluminescent signal intensity. Luminescence per cell tended to vary in association with the fraction of proliferating cells. CONCLUSION: Although in vivo bioluminescence imaging would allow non-invasive monitoring of leukaemia model animals, environmental factors and therapeutic interventions may cause some discrepancies between tumour burden and bioluminescence intensity.

Animals↗