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Masataka Uetani

Publications and source records attributed to Masataka Uetani.

At least 19 recordsLinked to original sources
PubMed2007

Extrahepatic collaterals and liver damage in embolotherapy for ruptured hepatic artery pseudoaneurysm following hepatobiliary pancreatic surgery.

AIM: To evaluate the effects of extrahepatic collaterals to the liver on liver damage and patient outcome after embolotherapy for the ruptured hepatic artery pseudoaneurysm following hepatobiliary pancreatic surgery. METHODS: We reviewed 9 patients who underwent transcatheter arterial embolization (TAE) for the ruptured hepatic artery pseudoaneurysm following major hepatobiliary pancreatic surgery between June 1992 and April 2006. We paid special attention to the extrahepatic arterial collaterals to the liver which may affect post-TAE liver damage and patient outcome. RESULTS: The underlying diseases were all malignancies, and the surgical procedures included hepatopancreatoduodenectomy in 2 patients, hepatic resection with removal of the bile duct in 5, and pancreaticoduodenectomy in 2. A total of 11 pseudoaneurysm developed: 4 in the common hepatic artery, 4 in the proper hepatic artery, and 3 in the right hepatic artery. Successful hemostasis was accomplished with the initial TAE in all patients, except for 1. Extrahepatic arterial pathways to the liver, including the right inferior phrenic artery, the jejunal branches, and the aberrant left hepatic artery, were identified in 8 of the 9 patients after the completion of TAE. The development of collaterals depended on the extent of liver mobilization during the hepatic resection, the postoperative period, the presence or absence of an aberrant left hepatic artery, and the concomitant arterial stenosis adjacent to the pseudoaneurysm. The liver tolerated TAE without significant consequences when at least one of the collaterals from the inferior phrenic artery or the aberrant left hepatic artery was present. One patient, however, with no extrahepatic collaterals died of liver failure due to total liver necrosis 9 d after TAE. CONCLUSION: When TAE is performed on ruptured hepatic artery pseudoaneurysm, reduced collateral pathways to the liver created by the primary surgical procedure and a short postoperative interval may lead to an unfavorable outcome.

Aged↗
PubMed2006

Diagnosis of perfusion abnormality of the pulmonary artery in Takayasu's arteritis using contrast-enhanced MR perfusion imaging.

To determine the clinical efficacy of contrast-enhanced magnetic resonance (MR) perfusion imaging in the diagnosis of perfusion abnormality in the pulmonary artery (PA) in Takayasu's arteritis (TA). Twenty-one patients were evaluated. Pulmonary MR perfusion images were acquired using a 2-dimensional (2D) fast spoiled gradient echo sequence with single-slice technique (TR/TE, 5.3/1.3; flip angle, 30 degrees; receiver bandwidth, 31.2 kHz/pixel; acquisition time, 0.7 s; and total acquisition time, 49 s). Seventy continuous subtracted MR images were evaluated, and the presence of perfusion abnormality was determined in lobe-based (n=126) and patient-based (n=21) analyses. Sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV) were calculated using perfusion scintigraphy as a standard reference. For lobe-based analysis, sensitivity was 91.7-95.8%, specificity was 92.2-93.7%, and PPV and NPV were 73.3-76.7% and 97.9-99.0%, respectively. For patient-based analyses, sensitivity was 100%, specificity was 72.7%, and PPV and NPV were 76.9% and 100%, respectively. Kappa values for each analysis were between 0.78-1.00. In conclusion, MR perfusion imaging appears to be a valuable, noninvasive method to estimate PA involvement in patients with TA.

Adult↗
PubMed2006

Pediatric CT scan usage in Japan: results of a hospital survey.

PURPOSE: The aim of this study was to examine the usage parameters of diagnostic computed tomography (CT) in children because of concerns of possible overuse in Japanese hospitals, including the "technical" CT exposure settings and the "clinical" grounds for CT requests. MATERIALS AND METHODS: We examined the methodology at the radiology department to reduce radiation exposure to children and performed a retrospective study on pediatric CT requests during a 1-year period at Nagasaki University Hospital. The parameters of diagnostic CT usage for minor head trauma and acute appendicitis were studied in detail. RESULTS: CT radiation dose settings are adjusted for children based on guidelines issued by the Japan Radiological Society, with few limitations. CT requests were made for 62% of minor head trauma cases and 76% of cases clinically suspected to be acute appendicitis. These figures are considerably higher than those reported by studies in the United Kingdom, Canada, or the United States. No specific guidelines are advocated regarding CT usage for minor head trauma. The diagnosis of acute appendicitis in children is almost routinely referred for "confirmation" by CT. CONCLUSION: CT radiation risks to children at Japanese hospitals need to be considered more seriously. Physicians should be encouraged to follow diagnostic algorithms that help avoid unnecessary CT usage in children.

Adolescent↗
PubMed2006

CT analysis of the growth rate of aortic diameter affected by acute type B intramural hematoma.

OBJECTIVE: The purpose of this study was to evaluate the growth rate of aortic diameter affected by acute type B intramural hematoma and the factors that influence its enlargement. MATERIALS AND METHODS: Fifty-four patients were entered into this study, and regular follow-up CT studies (mean +/- SD, 46.9 +/- 27.2 months; range, 5-136 months) were performed. The affected aortas and iliac arteries were divided into five segments. A total of 127 segments were evaluated (aortic arch, n = 47; descending thoracic aorta, n = 51; suprarenal abdominal aorta, n = 24; infrarenal abdominal aorta, n = 3; and iliac artery, n = 2). The growth rate of each segment was obtained on CT. The factors influencing increase in the diameter and growth rate--age, sex, diabetes mellitus, atherosclerotic disease, history of smoking 20 years, chronic renal failure, blood pressure, initial diameter of the lumen, the presence of blood flow in the false lumen--were evaluated by univariate analysis and a multivariate logistic regression model. RESULTS: Twenty (37.0%) of 54 patients had one or more segments that increased in size during the follow-up period. Of a total of 127 segments, 35 (27.6%) increased in size, and for all, the mean growth rate was -0.5 +/- 2.9 mm/year. This negative growth rate represents shrinkage. The mean growth rates within the first year and after 1 year from onset were -2.2 +/- 5.7 and 0.4 +/- 3.2 mm/year, respectively, and a significant difference was observed between them (p < 0.0001). An initial diameter of 40 mm or greater and the presence of blood flow in the false lumen were significant risk factors for an increase in the diameter, as confirmed by univariate and multivariate analyses. CONCLUSION: In patients with type B intramural hematoma, the affected aortas did not show a high incidence of enlargement during the follow-up period, but the affected aortas tended to increase in size after 1 year from onset. An initial diameter of 40 mm or greater and the presence of blood flow in the false lumen were important risk factors for enlargement during the follow-up period.

Adult↗
PubMed2006

MRI of Takayasu's arteritis: typical appearances and complications.

OBJECTIVE: Although Takayasu's arteritis (TA) is more common in Asian countries, it has a worldwide distribution. MRI is widely used for its diagnosis. Our purpose is to present a comprehensive pictorial review of its typical appearances and complications on MRI. CONCLUSION: MRI can effectively provide almost all anatomic information in patients with TA. MRI is very useful for accurate diagnosis of TA and its complications. Knowledge of MRI findings is essential for improving patient outcome.

Adult↗
PubMed2005

Multi-detector row CT imaging of vertebral microstructure for evaluation of fracture risk.

UNLABELLED: We applied MDCT for in vivo evaluation of the microarchitecture of human vertebrae. Microstructure parameters, such as structure model index, Euler's number, and bone volume fraction, revealed higher relative risk for prevalent vertebral fracture than did BMD obtained by DXA. Thus, microstructure analysis by MDCT, together with simultaneously obtained volumetric BMD values, is useful for clinical assessment of fracture risk. INTRODUCTION: BMD measurement by DXA alone has limitations in predicting fracture, and methods for clinical assessment of bone quality, such as microstructure, are awaited. This study was undertaken to examine the applicability of multidetector row CT (MDCT) for in vivo evaluation of trabecular microstructure. MATERIALS AND METHODS: Optimal conditions for MDCT scanning were determined at a spatial resolution of 250 x 250 x 500 mum, using muCT data of excised human vertebra specimens as a reference. We analyzed the trabecular microstructure of the vertebrae of 82 postmenopausal women (55-76 years old), including 39 women with and 43 without a recent vertebral fracture. RESULTS: Microstructure indices obtained by MDCT scanning revealed higher relative risk for prevalent vertebral fracture (OR: 16.0 for structure model index, 13.6 for bone volume fraction, and 13.1 for Euler's number) than did spinal BMD obtained by DXA (OR: 4.8). MDCT could also provide volumetric BMD data, which had higher diagnostic value (OR: 12.7) than did DXA. CONCLUSION: Vertebral microarchitecture can be visualized by MDCT, and microstructure parameters obtained by MDCT, together with volumetric BMD, provided better diagnostic performance for assessing fracture risk than DXA measurement.

Absorptiometry, Photon↗
PubMed2005

Effects of risedronate on trabecular microstructure and biomechanical properties in ovariectomized rat tibia.

We determined the effect of risedronate on the trabecular microstructure of ovariectomized rat tibiae, using micro-computed tomography, in order to investigate how changes in microstructure contribute to biomechanical properties. Fifty 18-week-old rats underwent sham operation (n=10) or ovariectomy (OVX) (n=40). The OVX rats were further divided into four groups (n=10 for each group) and treated with risedronate at doses of 0, 0.1, 0.5 or 2.5 mg/kg for 9 months. OVX caused deterioration of three-dimensional trabecular microstructure, notably structure model index (SMI) and connectivity density, while treatment of OVX rats with risedronate at 0.5 and 2.5 mg/kg improved those deleterious microstructural changes. Biomechanical property, as assessed by finite element analysis (FEA), correlated significantly with trabecular bone volume fraction (BV/TV), and the correlation further increased substantially when microstructural parameters were added, especially SMI and connectivity density, with risedronate therapy. Thus, it is suggested that, in addition to increasing bone mass, risedronate improves biomechanical property by maintaining a plate-like structure as well as connectivity of trabeculae.

Animals↗
PubMed2005

Endovascular treatment of iliac artery aneurysms.

Endovascular treatment is now an alternative to surgery for the treatment of iliac artery aneurysms (IAAs). A variety of minimally invasive therapeutic options are available (eg, coil embolization, stent-graft placement), and choosing an appropriate option is essential for achieving excellent long-term results and reducing potential complications. Preprocedural imaging with multi-detector row computed tomography or magnetic resonance imaging is necessary for evaluating patient eligibility and planning the interventional procedure. An imaging classification system for IAAs that is based on anatomic features and endovascular treatment options has been developed and may help determine therapeutic strategies for affected patients. Early experience indicates that endovascular treatment is safe and effective in treating IAAs, and it is expected that various devices that will make endovascular treatment easier to perform will soon become commercially available. However, large, long-term follow-up studies will be needed to determine whether this approach is a practical alternative to open surgery.

Aged↗
PubMed2005

[Normal radiographic anatomy of thoracic structures: analysis of 316 lateral chest radiographs].

PURPOSE: To study the frequency of visualization and characteristics of normal thoracic structures on lateral chest radiographs in the Japanese population. MATERIALS AND METHODS: We reviewed 316 lateral chest radiographs of men and women ranging in age from 20 to 90 years. The frequency of visualization and configuration of structures including major, minor, superior and inferior accessory fissures, and orifices of the right and left upper lobe bronchi were reviewed. RESULTS: On lateral chest radiographs, major fissure and minor fissure were visualized in 99.4% and 87.3%, respectively. Superior accessory fissure and inferior accessory fissure were visualized in 1.9% and 9.5%, respectively. Orifices of the right and left upper bronchi were seen in 92.4% and 98.4%, respectively. CONCLUSION: Frequency of visualization and characteristics of various normal anatomic structures on lateral chest radiographs in the Japanese population differ from those reported previously from the West. Familiarity with these normal thoracic structures and variations is important for daily image interpretation.

Adult↗
PubMed2004

Effect of etidronate on three-dimensional trabecular structure in ovariectomized or sciatic neurectomized rats.

The purpose of this study was to evaluate the effect of etidronate (EHDP) on three-dimensional (3D) trabecular structure in ovariectomized (OVX) and sciatic neurectomized (NX) rats. Eight-week-old female Lewis rats received ovariectomy ( n = 19) or sham operation (OVX-sham; n = 10). OVX rats received either vehicle (OVX-control; n = 9) or EHDP (OVX-EHDP; n = 10). Eight-week-old female Lewis rats received NX ( n = 20) or sham operation (NX-sham; n = 10). NX rats received either vehicle (NX-control; n = 10) or EHDP (NX-EHDP; n = 10). EHDP at 5 mg/kg or vehicle was subcutaneously injected 5 days a week. The treatment was initiated 2 weeks after surgery and was continued for 2 weeks. At 12 weeks of age, the rats were killed, and we scanned the proximal metaphysis of the tibia; this was done using micro-CT; (micro CT20; SCANCO Medical). The recovery of structural parameters was not complete in NX rats compared to OVX rats. The 3D micro-CT images showed that the subcortical spongiosa, which was preserved in OVX rats, had marked loss in NX rats. Furthermore, these trabeculae were not restored after the EHDP treatment. In conclusion, the mechanical driving of the control of trabecular structure is inactive in NX, and EHDP treatment for 2 weeks does not restore this condition.

Animals↗
PubMed2004

[Evaluation of strongly hyperintense area in breast lesions on fat-suppressed T2-weighted images correlated with histopathology].

The purpose of this study was to correlate strongly hyperintense areas(SHI) in breast lesions on FS-T2WI with histopathology and to evaluate the usefulness of the distribution patterns of SHI in the differentiation of benign and malignant breast lesions. MR imaging with pathological correlation was available in 157 breast lesions of 153 patients. The distribution patterns of SHI were classified into seven types. SHI on FS-T2WI was identified in 36 of 157 breast lesions. The irregular and inhomogenous types corresponded to various histological features and were only seen in malignant lesions. The central type corresponded to central necrosis and was only seen in 2 solid-tubular carcinomas. The crescent type corresponded to peripheral fluid collection in the intracystic tumor. The septal type corresponded to fibromyxoid stroma with fibrous septations in the lesions except for one cavernous hemangioma, and was only seen in benign lesions. The smooth type corresponded to mucinous pool, fibromyxoid stroma, and ductal dilatation and did not contribute to differentiation between benign and malignant lesions only on FS-T2WI. SHI in breast lesions on FS-T2WI pathologically corresponded to mucin, fibromyxoid change, necrosis, and ductal dilatation. Evaluation of patterns of SHI is useful in differentiating between benign and malignant lesions.

Adolescent↗
PubMed2003

Which bone densitometry and which skeletal site are clinically useful for monitoring bone mass?

Long-term precision, as well as reproducibility, is important for monitoring bone mineral density (BMD) alteration in response to aging or therapy. In order to investigate which bone densitometry and which skeletal site are clinically useful for monitoring bone mass, we examined the standardized long-term precision of several bone density measurements in 83 healthy Japanese women. Annual BMD measurements were performed for 5 or 6 years using dual X-ray absorptiometry (DXA) on the lumbar spine, radius (EXP5000) and calcaneus (HeelScan); peripheral quantitative computed tomography (pQCT) on the radius (Densiscan1000); and quantitative ultrasound (QUS) on the calcaneus (Achilles+). The long-term precision error for the individual subject was given by the standard error of estimate (SEE), and the standardized long-term precision was defined as the percentage coefficient of variation (CV%) divided by the percentage ratio of the annual bone-loss rate. Based on the CV% of spinal DXA, speed of sound (SOS) and diaphyseal pQCT showed significantly higher precision than others, while radial ultradistal (UD) DXA and heel DXA showed significantly lower precision. The long-term precision errors of other measurements were statistically the same as that of the spinal DXA. The spinal DXA, the radial DXA, and pQCT at both the distal metaphysis and diaphysis showed high rates of annual bone loss. The radial trabecular BMD (pQCT) was significantly higher than that of spinal DXA. The annual rates of bone loss of QUS and of heel DXA were significantly lower than that of spinal DXA. Taken together, standardized long-term precision was obtained in the spinal DXA and radial pQCT. In conclusion, spinal DXA and radial pQCT were considered the most useful monitoring method for osteoporosis, while QUS was considered less useful.

Absorptiometry, Photon↗
PubMed2003

Intrahepatic biloma formation (bile duct necrosis) after transcatheter arterial chemoembolization.

OBJECTIVE: The purpose of our study was to discuss the incidence, predisposing factors, and clinical course of intrahepatic biloma after transcatheter arterial chemoembolization for hepatic tumors including hepatocellular carcinoma and metastatic liver tumor. MATERIALS AND METHODS: Nine hundred seventy-two patients with hepatocellular carcinoma (n = 920) or metastatic liver tumor (n = 52) underwent chemoembolization during a 12-year period beginning in January 1989. We retrospectively reviewed the medical records and follow-up radiographs of chemoembolization and analyzed the risk factors associated with the development of intrahepatic biloma. RESULTS: Intrahepatic biloma developed after chemoembolization in 35 patients (3.6%, 35/972) in our series. The incidence of intrahepatic biloma formation in patients with metastatic liver tumor (9.6%, 5/52) was higher than that in patients with hepatocellular carcinoma (3.3%, 30/920) (p < 0.05, Fisher's exact test). The incidence of intrahepatic biloma formation in patients with hepatocellular carcinoma was statistically higher in patients with main tumor size of less than 5 cm and in those with the presence of intrahepatic bile duct dilatation. Technique-related risk factors such as injection site of drugs, repeated chemoembolization with frequency of less than 3 months, and regimen of chemoembolization significantly influenced the incidence of biloma formation in patients with hepatocellular carcinoma. No patient died of infected biloma or septicemia, but one patient died of hepatic failure 2 months after chemoembolization. CONCLUSION: Biloma formation was significantly more prevalent in the metastatic lesion group than in the hepatocellular carcinoma group. Significant prognostic factors for biloma formation in patients with hepatocellular carcinoma were tumor size of less than 5 cm, bile duct dilatation, proximal injection site, repeated injection with frequency of less than 3 months, and injection of a suspension of anticancer drugs.

Aged↗
PubMed2003

Discrimination of metastatic cervical lymph nodes with diffusion-weighted MR imaging in patients with head and neck cancer.

BACKGROUND AND PURPOSE: Metastasis to the regional cervical lymph nodes may be associated with alterations in water diffusivity and microcirculation of the node. We tested whether diffusion-weighted MR imaging could discriminate metastatic nodes. METHODS: Diffusion-weighted echo-planar and T1- and T2-weighted MR imaging sequences were performed on histologically proved metastatic cervical lymph nodes (25 nodes), benign lymphadenopathy (25 nodes), and nodal lymphomas (five nodes). The apparent diffusion coefficient (ADC) was calculated by using two b factors (500 and 1000 s/mm(2)). RESULTS: The ADC was significantly greater in metastatic lymph nodes (0.410 +/- 0.105 x 10(-3) mm(2)/s, P <.01) than in benign lymphadenopathy (0.302 +/- 0.062 x 10(-3) mm(2)/s). Nodal lymphomas showed even lower levels of the ADC (0.223 +/- 0.056 x 10(-3) mm(2)/s). ADC criteria for metastatic nodes (>/= 0.400 x 10(-3) mm(2)/s) yielded a moderate negative predictive value (71%) and high positive predictive value (93%). Receiver operating characteristic analysis demonstrated that the criteria of abnormal signal intensity on T1- or T2-weighted images (A(z) = 0.8437 +/- 0.0230) and ADC (A(z) = 0.8440 +/- 0.0538) provided similar levels of diagnostic ability in differentiating metastatic nodes. The ADC from metastatic nodes from highly or moderately differentiated cancers (0.440 +/- 0.020 x 10(-3) mm(2)/s, P <.01) was significantly greater than that from poorly differentiated cancers (0.356 +/- 0.042 x 10(-3) mm(2)/s). CONCLUSION: Diffusion-weighted imaging is useful in discriminating metastatic nodes.

Adult↗
PubMed2002

Bilateral elastofibroma of the thighs with concomitant subscapular lesions.

We report a case of elastofibroma that occurred in both thighs and subscapular regions. The MR signal intensity of the lesions was typical for elastofibroma. Although bilateral involvement of the thighs is exceptional, the presence of concomitant characteristic bilateral subscapular lesions was helpful in making the diagnosis of elastofibroma.

Aged↗