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Biomedical subjects

Hiromu Nishitani

Publications and source records attributed to Hiromu Nishitani.

At least 19 recordsLinked to original sources
PubMed2006

Quality assurance of I-125 seeds for prostate brachytherapy using an imaging plate.

PURPOSE: OncoSeed is delivered in a sterile environment in the form of a cartridge, so it is impractical to resterilize and reload seeds after calibration. We investigated a new method using an imaging plate dosimetry system to characterize all seeds in the OncoSeed cartridge in a sterile environment. METHODS AND MATERIALS: Seeds within the cartridge were placed on an imaging plate, and the imaging plate irradiated. To remove scatter radiation, and improve spatial resolution of seed images, we used X-ray parallel cross grids. The irradiated imaging plate was scanned using a Bio-imaging Analyzer System, and radioactivity intensities of seed images were given in counts. Counts could be translated to profiles, and each seed within the cartridge was analyzed. RESULTS: Results showed a good correlation between counts and total radioactivity of the seeds within the cartridge. Thus, using a least-squares line, it was possible to characterize a cartridge with unknown apparent activity. By analyzing the profiles, it was possible not only to detect a miscalibrated seed in the cartridge from its relative difference in counts, but also to identify its position in the cartridge. No significant changes in counts were seen between sterile and nonsterile environments. CONCLUSION: Using an imaging plate dosimetry system, all seeds in a cartridge could be characterized in a sterile environment.

Brachytherapy↗
PubMed2006

Pelvic bone complications following radiation therapy of gynecologic malignancies: clinical evaluation of radiation-induced pelvic insufficiency fractures.

OBJECTIVE: To investigate the incidence, clinical and imaging finding of insufficiency fractures (IF) of the female pelvis following radiation therapy. METHODS: We reviewed the radiation oncology records of 158 patients with gynecologic malignancies who underwent external beam radiation therapy of the whole pelvis between April 1993 and March 2004. All patients underwent computed tomography (CT) scan every 6 months in follow-up after radiation therapy and magnetic resonance imaging (MRI) and radionuclide bone scan were added when the patients complained of a pelvic pain. RESULTS: Eighteen of 158 patients (11.4%) developed IF in the irradiated field with a median interval of 6 months (range 3-51) from the completion of external beam radiation therapy. The cumulative incidence of symptomatic IF at 5 years calculated with Kaplan-Meyer methods was 13%. Median age of the patients who developed IF was 70 years (range 48-88), and all of them were postmenopausal. IF occurred in the sacloiliac joints, upper limb of pubic bone, acetabulum, sacral body and 5th lumbar vertebra. Twelve of 18 patients had multiple lesions and 8 had symmetric longitudinal fracture lines parallel to the sacroiliac joints. Avoidance of weight bearing by bed rest and analgesics provided good pain relief in all patients, although symptoms lasted from 3 to 20 months. CONCLUSIONS: Radiation-induced pelvic IF following radiation therapy for gynecologic malignancies were frequently observed in the postmenopausal patients within 1 year after external beam radiation therapy. Symmetric fractures of the both sacroiliac joints were the characteristic pattern of pelvic IF. Knowledge of characteristic imaging pattern of IF is essential in order to rule out the bone metastasis. Therapy recommendations are conservative with analgesics.

Aged↗
PubMed2006

Chemoradiation therapy for cervical cancer: toxicity of concurrent weekly cisplatin.

PURPOSE: To retrospectively evaluate the toxicity of concurrent weekly cisplatin and radiation therapy (RT) for locally advanced cervical cancer. MATERIALS AND METHODS: Between April 2001 and December 2004, 21 consecutive previously untreated patients with locally advanced cervical cancer were treated with concurrent chemoradiation therapy (CCRT) at the Tokushima University Hospital. Clinical stages were II: 5, III: 15, IVA: 1. External beam radiation therapy (EBRT) was delivered with 10 MV X-rays, 2 Gy fraction per day; total dose to the whole pelvis was 50 Gy. Iridium-192 high-dose-rate (HDR) intracavitary radiation therapy was performed with 10-30 Gy (median, 24 Gy) targeted at point A. Concurrent chemotherapy consisted of cisplatin, administered weekly at a dose of 40 mg/m2 for patients who were younger than 65 years and 30 mg/m2 for those 65 years or over. A maximum single dose of cisplatin, up to 70 mg/body, was administered in 5 cycles during EBRT. RESULTS: A total of 86 cycles of cisplatin were administered to the 21 patients, with a median of 4 cycles (range, 2-5). Severe hematological toxicity occurred in 18 patients (86%), including grade 3 in 17 patients (81%) and grade 4 in one patient (4.8%). Moderate or severe gastrointestinal toxicity occurred in 11 patients (52%), including grade 2 in 10 patients (48%) and grade 3 in one patient (4.8%). The grades of hematological toxicity were significantly greater in the 40 mg/m2 group than in the 30 mg/m2 group. All of the patients who were administered 40 mg/m2 of cisplatin developed grade 3 or greater hematological toxicity, including one patient with grade 4 toxicity. In the 30 mg/m2 group, 3 of 10 patients developed less than grade 3 toxicity, and all patients completed radiation therapy without interruption. CONCLUSION: The incidence of severe acute hematological toxicity was significantly higher in this study than in previously reported randomized controlled trials (RCTs), especially in the group of 40 mg/m2 cisplatin. A dose of 30 mg/m2 of cisplatin was considered to be feasible in weekly cisplatin and radiation therapy.

Aged↗
PubMed2006

Change of diffusion anisotropy in patients with acute cerebral infarction using statistical parametric analysis.

PURPOSE: We conducted statistical parametric comparison of fractional anisotropy (FA) images and quantified FA values to determine whether significant change occurs in the ischemic region. MATERIALS AND METHODS: The subjects were 20 patients seen within 24 h after onset of ischemia. For statistical comparison of FA images, a sample FA image was coordinated by the Talairach template, and each FA map was normalized. Statistical comparison was conducted using SPM99. Regions of interest were set in the same region on apparent diffusion coefficient (ADC) and FA maps, the region being consistent with the hyperintense region on diffusion-weighted images (DWIs). The contralateral region was also measured to obtain asymmetry ratios of ADC and FA. RESULTS: Regions with areas of statistical significance on FA images were found only in the white matter of three patients, although the regions were smaller than hyperintense regions on DWIs. The mean ADC and FA ratios were 0.64 +/- 0.16 and 0.93 +/- 0.09, respectively, and the degree of FA change was less than that of the ADC change. Significant change in diffusion anisotropy was limited to the severely infarcted core of the white matter. CONCLUSION: We believe statistical comparison of FA maps to be useful for detecting different regions of diffusion anisotropy.

Acute Disease↗
PubMed2006

ALK7 is a novel marker for adipocyte differentiation.

Transforming growth factor-beta (TGF-beta) family members regulate a variety of cellular functions and play important roles in cell differentiation. Activin receptor-like kinase 7 (ALK7), a receptor for TGF-beta family members, was initially cloned from rats as an orphan receptor and has been recently shown to be a type I receptor for nodal, activin B and activin AB. ALK7 is expressed not only in neurons, but also in insulin-producing islet beta cells and white and brown adipose tissues; however, the specific functions of ALK7 in these tissues are not known. In order to test whether ALK7 is involved in adipocyte differentiation, we analyzed its expression during adipocyte differentiation. ALK7 expression was detected in the late phase of adipocyte differentiation by reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting and immunofluorescence staining in 3T3-L1 cells. We also detected the expression of ALK7 by RT-PCR in stromal vascular fraction (SVF) cells. These results indicated that ALK7 is a novel marker specifically expressed during the late phase of adipocyte differentiation. Furthermore, our results suggest the possible involvement of nodal or activin B in adipocyte differentiation.

Activin Receptors, Type I↗
PubMed2006

Risk factors associated with soft coronary artery plaques in Japanese, as determined by 16 slice multidetector-row computed tomography.

PURPOSE: The acute coronary syndrome is often caused by the rupture of plaques and thrombus formation even without significant stenosis, and patients with soft plaques, but without significant stenosis evidenced by coronary angiography (CAG), often develop an acute coronary syndrome. To address this discrepancy, a qualitative diagnosis of coronary plaques using a 16 slice multidetector-row CT was conducted. METHODS AND RESULTS: Volume rendering and cross-sectional MPR images were obtained. Based on the CT values, plaques on the coronary artery wall were classified as lipid-rich soft plaques (CT value<50 HU) and non-soft plaques (>50 HU).A significant correlation was observed between the percent stenosis determined in cross-sectional MPR images and those determined by CAG (r=+0.92, p<0.01). Diffuse plaques with CT values of less than 50 HU often caused stenosis at level of 75% or less, which were not indicated by percutaneous transluminal coronary angioplasty. CONCLUSIONS: Although diffuse soft plaques with CT values less than 50 HU are not an indication of intervention, a risk of an acute coronary syndrome exists, due to rupture. These soft plaques must be stabilized by treatment even when they do not cause significant stenosis, and MDCT is considered to be useful for their evaluation.

Aged↗
PubMed2006

Hemodynamic changes with liver fibrosis measured by dynamic contrast-enhanced MRI in the rat.

PURPOSE: To evaluate the hemodynamic changes of liver cirrhosis in the rat and investigate the relationship between hemodynamic changes and properties of fibrotic change in the liver. MATERIALS AND METHODS: Three rats with cirrhosis induced by thioacetamide (TAA), three with disease induced by carbon tetrachloride (CCl4), and three with no treatment were measured on dynamic MRI using a 1.5T scanner. Compartment and moment analysis were used to quantitate hemodynamic changes. RESULTS: Compartment model analysis showed that increased transition speed from vessels to the liver correlated with grade of liver fibrosis. Moment analysis demonstrated that decrease of area under the curve (AUC), mean residence time (MRT), variance of residence time (VRT), half life (T1/2) and increased total clearance (CL) correlated with grade of liver fibrosis. CONCLUSIONS: Hemodynamic changes in injured fibrotic liver may be influenced by the grade of fibrosis. Compartment model and moment analysis may be useful for evaluating hemodynamic changes in injured liver.

Animals↗
PubMed2005

Pathologies of the uterine endometrial cavity: usual and unusual manifestations and pitfalls on magnetic resonance imaging.

The endometrial cavity may demonstrate various imaging manifestations such as normal, reactive, inflammatory, and benign and malignant neoplasms. We evaluated usual and unusual magnetic resonance imaging (MRI) findings of the uterine endometrial cavity, and described the diagnostic clues to differential diagnoses. Surgically proven pathologies of the uterine endometrial cavity were evaluated retrospectively with pathologic correlation. The pathologies included benign endometrial neoplasms such as endometrial hyperplasia and polyp, malignant endometrial neoplasms such as endometrial carcinoma and carcinosarcoma, endometrial-myometrial neoplasm such as endometrial stromal sarcoma, pregnancy-related lesions in the endometrial cavity such as gestational trophoblastic diseases (hydatidiform mole, invasive mole and choriocarcinoma) and placental polyp, myometrial lesions simulating endometrial lesions such as submucosal leiomyoma and some adenomyosis, endometrial neoplasms simulating myometrial lesions such as adenomyomatous polyp and endometrial lesions arising in the hemicavity of a septate/bicornate uterus, and fluid collections in the uterine cavity (hydro/hemato/pyometra). It is important to recognize various imaging findings in these diseases, in order to make a correct preoperative diagnosis.

Adult↗
PubMed2005

The impact of FDG-PET in the management of patients with salivary gland malignancy.

OBJECTIVE: The aim of this study was to evaluate the impact of FDG-PET in the management of patients with salivary gland malignancy. PATIENTS AND METHODS: We performed 45 FDG PET studies in 31 patients with salivary malignant tumors, using PET (33 studies) and PET/CT (12 studies). Patients comprised 21 males and 10 females with a mean age of 69 y (range 38-89). Nineteen patients had a single study, ten patients had 2 and two patients had 3 studies. Twelve studies were performed for initial staging and 33 studies for restaging. Four patients of the initial staging group were restaged with PET after therapy. Histology consisted of 8 adenocarcinomas, 8 squamous cell carcinomas, 4 adenoid cystic carcinomas, 4 carcinoma ex pleomorphic adenomas, 2 mucoepidermoid carcinomas, 2 poorly differentiated carcinomas, 1 salivary duct carcinoma, 1 lymphoepithelial carcinoma and 1 melanoma. PET findings were reviewed with the clinical and radiologic findings and the impact of PET on staging and patient management was determined. RESULTS: In the initial staging group, all 12 primary lesions (100%) showed positive FDG uptake (5 squamous cell carcinomas, 2 adenocarcinomas, 2 poorly differentiated carcinomas, 1 carcinoma ex pleomorphic adenoma, 1 salivary duct carcinoma, 1 lymphoepithelial carcinoma). Three patients (25%) had FDG positive distant disease (liver, bone, lymph nodes); surgery was canceled and therapy changed to chemoradiation. One patient (9%) with no FDG uptake in the neck nodes avoided a planned neck dissection. In the restaging group (33 studies in 23 patients), 5 patients (22%) had FDG positive distant disease, which changed the treatment from surgery to chemoradiation or other. A second primary lesion was detected in one patient (4%). One patient (4%) with clinically suspected recurrence was able to avoid other invasive procedures because of the negative PET. Overall, FDG PET resulted in a major change in management in 11 of 31 patients (35%). CONCLUSION: This study shows that FDG PET has a significant impact on the management of patients with salivary malignant tumors in both the initial staging and restaging.

Adult↗
PubMed2005

FDG-PET/CT findings of sarcomatous transformation in neurofibromatosis: a case report.

We herein report FDG-PET/CT findings of sarcomatous transformation in a patient with neurofibromatosis type 1 (NF-1). About 5% of patients with NF-1 develop sarcomatous transformation of a malignant peripheral nerve sheath tumor which arises from plexiform neurofibromas and is often associated with a poor prognosis. Morphologic imaging techniques such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) are the standard methods to define the anatomic extent of the tumor, although tumor heterogeneity prevents reliable differentiation between benign and malignant lesions. The degree of fluoro-deoxyglucose (FDG) uptake correlates with histologic grade in neurogenic tumors in NF-1 patients. Our patient had a huge mass in the left gluteus area with a large nearly circular focus of increased FDG uptake in the tumor. The mass had a photopenic center. The maximum Standard Uptake Value (SUVmax) of this mass was 6.6. There was CT evidence of invasion of the left iliac wing, left acetabulum, and left superior pubic ramus; however there was no increased FDG uptake in these areas on the PET study. We surmised that the high FDG uptake indicated a high grade sarcoma, which was confirmed histologically. There was also a focal region of increased uptake in the L5 vertebral body, correlating with the CT hypodense lesion, with 2.9 SUVmax. FDG-PET/CT can identify sarcomatous change from benign neurogenic tumor with minimal misregistration, and can also detect metastatic disease. This case illustrates the importance of evaluating both metabolic and morphologic abnormalities to be able to formulate a proper treatment plan. This information can be obtained in a single session, using PET/CT.

Adult↗
PubMed2005

The effect of oral contrast on large bowel activity in FDG-PET/CT.

PURPOSE: The purpose of this study was to determine the effect of oral contrast on FDG uptake in the colon and to determine the normal distribution of FDG in the colon. METHODS: Sixty patients (30 patients in no contrast group and 30 patients in the received contrast group) underwent FDG-PET/ CT scans. The pattern of FDG uptake was classified into 5 patterns (diffuse, segmental, single-nodular, multi-nodular, and other) in 5 segments (ascending, transverse, descending, and rectosigmoid colon). SUVs of the no oral contrast group were examined. The ratios of FDG uptake patterns were compared in the received contrast group and no contrast group to evaluate the effect of oral contast. The effect of attenuation correction on the uptake pattern was evaluated by comparison of the attenuation-corrected and non-attenuation-corrected PET images. RESULTS: In the no contrast group, there was no significant uptake in 72 segments (59%) and a diffuse pattern was seen in 29 segments (24%), most frequently in the ascending colon and descending colon. A segmental pattern was seen in 15 segments (13%), most frequently in the rectosigmoid colon. A single-nodular pattern was seen in 3 segments (3%) and multi-nodular pattern in 1 segment (1%). A nodular pattern was seen only in the ascending colon. SUVmax of the ascending colon and that of the rectosigmoid colon were significantly higher than those of the transverse and descending colon. The frequencies of diffuse, multi-nodular and 'other' patterns were significantly higher in the received contrast group than in no contrast group. There was no significant difference between the frequency of the segmental pattern or the single nodular pattern in the two groups. There was no significant difference between the uptake patterns with attenuation correction and those without attenuation correction in either the received contrast group or no contrast group. CONCLUSION: Normal FDG uptake in the large bowel may show various degrees and patterns of uptake among the colonic segments. Oral contrast agent can cause focal or diffuse increased FDG uptake, which may be induced not only by the high CT density of oral contrast but also by an accelerated physiologic reaction of the large bowel.

Administration, Oral↗
PubMed2005

Regional changes of fractional anisotropy with normal aging using statistical parametric mapping (SPM).

OBJECTIVE: There has been reports on the usefulness of diffusion tensor imaging (DTI) about age-or disease-related degradation. DTI is generally evaluated by the region of interest (ROI) methodology. In this study, we applied a statistical way using Statistical Parametric Mapping (SPM) to assess normal aging by DTI and compared results of these two methods. METHODS: Ten young and ten senior normal volunteers were examined. On SPM, tensor images were changed into normalized tensor images. They were compared between the two groups by t-test. RESULTS: In the senior group, fractional anisotropy (FA) values were higher on the basal ganglia, cingulated gyrus and other cortical gray matter, lower in the corona radiata, internal capsule, centrum semiovale and corpus callosum by using SPM. In the ROI method, the results were almost compatible except in the brain periphery. CONCLUSIONS: Aging changes on water diffusion anisotropy was clearly shown by SPM method which would be useful to evaluate change of water diffusion anisotropy without operator bias even in clinical setting instead of ROI measurement.

Adult↗
PubMed2005

Cerebral hyperperfusion in a patient with eclampsia with perfusion-weighted magnetic resonance imaging.

The patient was a 25-year-old Japanese woman with postpartum eclampsia, in whom magnetic resonance imaging (MRI) was performed ten hours after convulsion. The patient improved within three days. Diffusion-weighted images showed a high apparent diffusion coefficient (ADC), and perfusion-weighted images obtained by the multi-slice flow-sensitive alternating inversion recovery (FAIR) method showed hyperperfusion, which was suggestive of vasogenic edema, on the parietal and occipital subcortical white matter, corresponding with transient hyperintensities on T2-weighted images. MR angiography (MRA) revealed no signs of vasospasm. These findings suggested hyperperfusion-induced vasogenic edema without cerebrovascular spastic change in the early stage of eclampsia. The FAIR method is considered a useful technique for perfusion-weighted MRI, especially useful to evaluate the cerebral perfusion of emergency patients such as those with eclampsia.

Adult↗
PubMed2005

A case of adenomyomatous polyp of the uterus associated with tamoxifen therapy.

A case of adenomyomatous polyp of the uterine endometrium is reported. The patient was 64-year-old woman treated with tamoxifen. Ultrasonography demonstrated a heterogeneous hyperechoic mass with small cystic spaces in the uterus. On magnetic resonance imaging (MRI), a thick stalk with many thin restiform branches within a large solid and cystic endometrial mass showed dendriform low intensity on T2-weighted images and intense enhancement on contrast-enhanced T1-weighted images. The prominent dendriform central fibrous core on MRI reflected a thick stalk originating from the myometrium with numerous branches containing abundant smooth muscle fibers, and may represent the pathologic feature of adenomyomatous polyp.

Adenomatous Polyps↗
PubMed2005

Quality assurance of I-125 seed permanent implant therapy using a self-color developing reflection-type dosimetry sheet film.

PURPOSE: We evaluated a self-color developing sheet-type film for the detection of dead seeds in I-125 permanent implant therapy for prostate cancer. MATERIALS AND METHODS: As a preliminary study, we irradiated X-rays to a self-developing reflection-type sheet film and created a relational curve between absorbed dose and film density. I-125 seeds were placed on a film and the approximate absorbed dose of I-125 was calculated from the relational curve of X-rays. A cartridge in which a dead seed was loaded among 10 I-125 seeds was placed on the film and the detectability of the dead seed was evaluated. RESULTS: Using the relational curve of X-rays, it was possible to measure the approximate absorbed dose of I-125 seeds and to easily detect a dead seed at a glance. Using sterilized film, it was possible to detect a dead seed. CONCLUSION: The self-developing film method is feasible for the detection of a dead seed in a cartridge without re-sterilization of seeds.

Brachytherapy↗
PubMed2004

Correlation between flow-sensitive alternating inversion recovery perfusion imaging with different inversion times and cerebral flow reserve evaluated by single-photon-emission computed tomography.

The purpose of this study was to evaluate the effect of different inversion times (TIs) on flow-sensitive alternating inversion recovery (FAIR) perfusion imaging and compare them with the cerebral blood flow reserve evaluated by acetazolamide challenge using single-photon-emission computed tomography (SPECT). The subjects were nine patients with unilateral obstruction of the internal carotid artery. The signal ratio (SR16/8) of two images with different TIs (1,600 ms and 800 ms) was calculated, and the cerebral blood flow reserve (CFR) was evaluated by the increase in the ratio of cerebral perfusion after administration of acetazolamide in the SPECT study. A reversed linear correlation ( r=0.75) was found between SR and CFR, indicating that differences of FAIR images with changes of TI will be affected by cerebral flow reserve.

Acetazolamide↗
PubMed2004

Clinical utility of FDG PET.

The aim of this article is to introduce the clinical utility of FDG PET as oncologic imaging. PET (positron emission tomography) is a newly developed imaging tool, and it has increased the accuracy of metabolic mapping of numerous malignancies, with significant impact on the management of cancer patients for initial staging, restaging and therapy monitoring. PET can provide functional information in addition to morphology from conventional imaging modalities. 18F-labeled 2-fluoro-2-deoxyglucose (FDG) is the most commonly used PET tracer and FDG PET can demonstrate the activity of glucose metabolism throughout the entire body in a single session. We describe the clinical utility of FDG in PET and display images of normal distribution and of patients with head and neck and lung cancer.

Data Interpretation, Statistical↗