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Yoshito Tsushima

Publications and source records attributed to Yoshito Tsushima.

At least 19 recordsLinked to original sources
PubMed2006

The posterior communicating arteries in the patients with sudden deafness: evaluation with magnetic resonance imaging (MRA).

BACKGROUND: A strong association was suggested between a non-functioning posterior communicating artery (Pcom) of the circle of Willis and sudden deafness (SD). The purpose of this study was to determine the rate of depiction of Pcom on magnetic resonance angiography (MRA) in patients with SD. METHODS: Sixteen patients with SD (47.7 +/- 13.3 years; range, 24 - 76 years; nine males) were evaluated with intracranial MRA as well as magnetic resonance imaging (MRI) of the head. The depiction of Pcom on MRA was correlated with the laterality of SD. One hundred twenty-eight controls (49.1 +/- 8.4 years; range, 22-66 years; 87 male) were selected from neurologically normal subjects who underwent MR examinations as a part of an annual medical check-up in our hospital. RESULTS: Four (25%) of 16 SD patients had bilateral Pcom on MRA, four patients had unilateral Pcom and eight patients had bilaterally absent Pcom These results were not significantly different from the controls (p = 0.96). In 6 (37.5 %) of 16 SD patients, the ipsilateral Pcom was present on MRA, and 104 (40.6%) of 256 Pcom were present in 128 normal controls (p = 0.81). CONCLUSION: Since there was no link between the occurrence of SD and the absence of the ipsilateral Pcom, our results cannot support the hypothesis that the absence of Pcom may be a risk factor for the occurrence of SD.

Journal Article↗
PubMed2005

Automated image-matching technique for comparative diagnosis of the liver on CT examination.

When interpreting enhanced computer tomography (CT) images of the upper abdomen, radiologists visually select a set of images of the same anatomical positions from two or more CT image series (i.e., non-enhanced and contrast-enhanced CT images at arterial and delayed phase) to depict and to characterize any abnormalities. The same process is also necessary to create subtraction images by computer. We have developed an automated image selection system using a template-matching technique that allows the recognition of image sets at the same anatomical position from two CT image series. Using the template-matching technique, we compared several anatomical structures in each CT image at the same anatomical position. As the position of the liver may shift according to respiratory movement, not only the shape of the liver but also the gallbladder and other prominent structures included in the CT images were compared to allow appropriate selection of a set of CT images. This novel technique was applied in 11 upper abdominal CT examinations. In CT images with a slice thickness of 7.0 or 7.5 mm, the percentage of image sets selected correctly by the automated procedure was 86.6+/-15.3% per case. In CT images with a slice thickness of 1.25 mm, the percentages of correct selection of image sets by the automated procedure were 79.4+/-12.4% (non-enhanced and arterial-phase CT images) and 86.4+/-10.1% (arterial- and delayed-phase CT images). This automated method is useful for assisting in interpreting CT images and in creating digital subtraction images.

Aged↗
PubMed2005

Prevalence of abnormal findings on brain magnetic resonance (MR) examinations in adult participants of brain docking.

BACKGROUND: To determine the prevalence of abnormal findings on brain magnetic resonance (MR) examinations in adult participants of brain docking in order to assess its usefulness. METHODS: We analyzed screening brain MR examinations for 1113 adults (age, 52.6+/-8.5 years; range, 22-84; 761 male and 352 female) performed during 6-year period from April 1998 to March 2004. All participants voluntarily sought a brain MR examination at their own expense. All subjects were studied using the same 1.0-T MR scanner, on axial T1-weighted spin echo (SE) images, proton-density-weighted and T2-weighted fast SE images, and intracranial MR angiography (MRA). All abnormal findings were classified into three basic categories: (1) findings with no referral necessary; (2) findings not requiring further evaluation, but which needed to be reported to the referring physician; (3) findings requiring further evaluation. RESULTS: Participants with abnormal MR findings requiring further evaluation accounted for 1.3 %, but five of seven suspected intracranial aneurysms were not confirmed by other imaging modalities (false positive). No malignant tumors or other life-threatening pathology was detected, and only three participants (0.27 %) with abnormalities underwent surgical treatment. No participant groups were identified from our data as being high risk for MR abnormal findings requiring further evaluation. CONCLUSION: Brain-docking participants had a variety of abnormalities on brain MR examinations, but only a small percentage of these findings required further evaluation. The usefulness of the brain docking with MRI and MRA has yet to be proven, and at this time we cannot approve this screening procedure.

Adult↗
PubMed2005

MR imaging in the evaluation of chronic or recurrent headache.

PURPOSE: To evaluate ability of magnetic resonance (MR) imaging to depict an abnormality in patients with chronic or recurrent headache without neurologic abnormality. MATERIALS AND METHODS: Institutional review board approval and patient informed consent were not required. A total of 306 patients with normal neurologic findings and chronic or recurrent headache were examined with MR imaging. Patients were divided into three groups: those with no abnormality, those with minor abnormality, and those with clinically important intracranial abnormality, which may result in chronic or recurrent headache. Literature review was also performed. Upper 99.5% confidence bound for frequency of abnormal MR findings was calculated. RESULTS: A total of 169 patients (55.2%) were placed in the first group, 135 (44.1%) were placed in the second group, and two (0.7%) were placed in the third group because they had a clinically important abnormality at MR imaging. Neither contrast material enhancement (n = 195) nor repeated MR imaging (n = 23) contributed to the diagnosis. Literature review revealed two previous studies concerning unspecified headache (in addition to the current study), including a total of 1036 MR imaging results and 22 (2.1%) clinically important results (upper 99.5% confidence bound, 3.4%). Twelve studies of migraine headache were found, with a total of 790 MR imaging examinations. Excluding the 19 patients with complicated migraine, the 99.5% confidence bound of the frequency of clinically important abnormality at MR imaging was estimated as 0.68%. Clinically important infarctions were noted on MR images in five (26.3%) of 19 patients with complicated migraine. CONCLUSION: MR imaging is an unrewarding technique in the evaluation of patients with chronic or recurrent headache and normal neurologic findings. Neither contrast enhancement nor repeated MR imaging contributed to diagnosis, although the number of patients in the latter category was small.

Adult↗
PubMed2004

Analysis models to assess cost effectiveness of the four strategies for the work-up of solitary pulmonary nodules.

BACKGROUND: To evaluate the role of computed tomography (CT) -guided needle biopsy and sodium iodide fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in the investigation of solitary pulmonary nodules (SPN), which are discovered on screening chest radiographs, and to determine the cost-effectiveness of these modalities. MATERIAL/METHODS: We have used decision-tree analysis models to assess the accuracy and cost-effectiveness of four strategies for the diagnosis and management of SPNs: CT alone strategy (baseline), CT plus FDG-PET strategy, CT plus FDG-PET plus CT-guided needle biopsy strategy, and CT plus CT-guided needle biopsy strategy. Reported values of prevalence of cancer, and sensitivity and specificity of each diagnostic modality were applied to the decision-tree models using Japanese health care costs. RESULTS: The prevalence of lung cancer among SPNs discovered on the lung cancer screening was less than 10%. In this prevalence, the strategies using CT-guided needle biopsy were the cost-effective alternatives to the CT alone strategy (cost saving was 436,470 yen - 456,478 yen per patient), and had higher accuracies (95-96% vs. 67%). Both effects were mainly the result of reducing the number of the candidates who undergo unnecessary thoracotomy for a benign SPN, and these results were true over a wide range of prevalence of cancer (0-55%). The cost saving and accuracy of the CT plus FDG-PET strategy (359,206 and 92%) were approaching to those of the strategies using CT-guided needle biopsy. CONCLUSIONS: The introduction of CT-guided needle biopsy and FDG-PET for the evaluation of SPNs, which are discovered on screening chest radiograph, is potentially cost-effective in Japan with high accuracy.

Cost-Benefit Analysis↗
PubMed2004

Noninvasive determination of regional myocardial perfusion with first-pass magnetic resonance (MR) imaging.

RATIONALE AND OBJECTIVES: To develop a method to provide absolute values of regional myocardial perfusion by means of color maps, and to determine myocardial perfusion reserve using magnetic resonance imaging during the first pass of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). MATERIALS AND METHODS: The study population consisted of five patients with hypertrophic cardiomyopathy, two with dilated cardiomyopathy, four with coronary artery disease, and one with normal coronary arteries who presented with mildly abnormal electrocardiogram findings. For each heartbeat, six continuous slices were acquired during the first pass of Gd-DTPA (0.05 mmol/kg body weight) before and during adenosine triphosphate (ATP) **stress using an electrocardiogram-triggered fast low-angle shot (FLASH) sequence on a 1.5-T magnetic resonance unit. Myocardial perfusion images were created and displayed by means of a color scale. The parameters were calculated pixel by pixel, using the upslope method. Myocardial perfusion reserve was then calculated, as the quotient of myocardial perfusion during ATP stress and perfusion before ATP stress. RESULTS: Myocardial perfusion during ATP stress in patients with normal coronary arteries (n = 1) or after successful percutaneous coronary intervention (n = 2) was increased compared with that before ATP stress. However, the patients with coronary artery disease (n = 2) failed to show increased myocardial perfusion. The patients with hypertrophic cardiomyopathy showed increased myocardial perfusion during ATP stress, although two with dilated cardiomyopathy did not. CONCLUSION: Our new technique can provide absolute values of regional myocardial perfusion by means of color maps, and has potential for widespread use for evaluation of ischemic and other types of heart disease.

Adenosine Triphosphate↗
PubMed2004

Quantitative perfusion map of malignant liver tumors, created from dynamic computed tomography data.

RATIONALE AND OBJECTIVES: To apply perfusion computed tomography (CT) technique to variable malignant liver tumors, and to define the usefulness of quantitative color mapping. MATERIALS AND METHODS: Perfusion CT images were created for 36 malignant liver tumors in 28 patients (age, 66.4 +/- 10.1 years; range, 48-85) with metastatic liver tumors (n = 17; nine colorectal carcinomas, eight other malignant tumors) and hepatocellular carcinomas (n = 11). A single-slice dynamic CT was performed after an intravenous bolus injection of 40 mL of contrast material (320 mgI/mL) with 8 mL/sec. The parameters were calculated pixel-by-pixel using maximum slope method, and quantitative maps of arterial and portal perfusion were created. In four patients who underwent transcatheter arterial chemoembolization, perfusion CT was performed before and after transcatheter arterial chemoembolization. RESULTS: In all patients, liver tumors were shown as hypervascular lesions on arterial perfusion CT. The average arterial perfusion value of the metastatic tumors from the colorectal carcinomas was 0.67 +/- 0.33 mL/min/mL, and that of hepatocellular carcinomas was 0.94 +/- 0.26 mL/min/mL (P = .03). The other metastatic tumors from various primary tumors showed a wide range (0.19-1.45 mL/min/mL) of arterial perfusion. Arterial perfusion of the liver tumors was obviously decreased after successful transcatheter arterial chemoembolization. In 12 of 15 tumors, in which portal perfusion CT images could be created, region-of-interest analysis showed no portal perfusion in the tumors. In two cases, decreased portal perfusion in the segments, which malignant tumors involved, was demonstrated. CONCLUSION: Perfusion CT can provide quantitative information about arterial and portal perfusion of liver tumors, combined with good anatomic detail in one image. This technique has a potential to evaluate the angiogenesis of liver tumors, to show secondary changes in perfusion, such as decreased portal perfusion in apparently normal liver adjacent to metastases, and to monitor the therapeutic response in vivo.

Aged↗
PubMed2003

High [18F] 2-fluoro-2-deoxy-D-glucose (FDG) uptake of adrenocortical adenoma showing subclinical Cushing's syndrome.

A 48-year-old woman with left adrenal tumor, which showed increased uptake of [18F] 2-fluoro-2-deoxy-D-glucose (FDG) was presented. Her adrenal tumor was incidentally discovered, although she had no remarkable illness, and her blood pressure was normal. Hormonal examination including dexamethason suppression test and diurnal variation in serum cortisol level confirmed preclinical Cushing's syndrome. CT, MRI and 131I-adosterol scintigraphy showed findings consistent with adenoma. FDG-PET revealed that tumor had standardized uptake value of 4.8, which was higher than usual benign tumors. Histological diagnosis of the resected adrenal tumor was adrenocortical adenoma without evidence of malignancy. Although the current literature showed that adenomas in general did not exhibit increased FDG uptake, adenoma in the present case with subclinical Cushing's syndrome showed intense uptake of FDG, suggesting FDG-PET could evaluate hormonal function of an adrenocortical adenoma in a completely asymptomatic normocortisolism patient.

Adrenal Cortex Neoplasms↗
PubMed2003

The effect of fatty infiltration on the liver tissue enhancement during portal phase computed tomography.

RATIONALE AND OBJECTIVES: To correlate the presence of fatty liver and the enhancement value of liver tissue during portal phase computed tomography. MATERIALS AND METHODS: Liver tissue enhancements during portal phase computed tomography were measured in 16 fatty liver and 35 control patients. All patients intravenously received 100 mL of non-ionic contrast material (320 mg iodine/ mL) at a rate of 3 mL/second, and the image acquisition started at 70 seconds. Attenuation values were measured on the 80-second portal phase images and the corresponding unenhanced images, and the contrast enhancement value (HU) of the liver tissue was calculated. Adjusted enhancement values were also calculated with the following equation: adjusted enhancement value = enhancement value (HU)/[dose (grams of iodine)/body weight (kg)]. RESULTS: The contrast enhancement value was significantly reduced in the fatty liver patients compared with the normal controls (37.0 +/- 7.2 vs 49.8 +/- 12.0 HU; P < .0001). This difference was still significant in adjusted enhancement value (80.1 +/- 13.7 vs 93.6 +/- 23.0 HU kg g(-1); P = .01). CONCLUSION: The liver tissue with fatty infiltration was less enhanced than controls, probably because of decreased portal perfusion.

Case-Control Studies↗
PubMed2003

Contribution of the diagnostic test to the physician's diagnostic thinking: new method to evaluate the effect.

RATIONALE AND OBJECTIVES: The purpose of this study was to develop and test a method for evaluating the effect of diagnostic tests on physicians' diagnostic thinking. MATERIALS AND METHODS: The authors applied the method to data obtained in a previous study. The diagnoses of surgeons in the emergency department before and after contrast material-enhanced computed tomography (CT) and their certainty were collected from the cases of 125 adult patients with acute abdominal pain. When the pre- or post-CT diagnosis was not consistent with the final diagnosis, the diagnostic certainty reported by a physician was converted to a negative value (true diagnostic certainty). Change in true diagnostic certainty was calculated by subtracting the values for diagnostic certainty before CT from those after CT. RESULTS: In 118 cases, the change in true diagnostic certainty was positive, which indicates that the CT information was beneficial for the physician's diagnostic thinking. The true diagnostic certainty before CT was 32.9% +/- 57.6 (range: -90% to 100%; 95% confidence interval: 22.7%, 43.1%) and that after CT was 73.4% +/- 37.0 (range: -80% to 100%; 95% confidence interval: 66.8%, 80.0%; P < .0001). Thus, the increase in true diagnostic certainty was 40.5% +/- 58.8 (range: -160% to 170%; 95% confidence interval: 30.1%, 69.2%). CONCLUSION: This method may be useful for estimating the effect of diagnostic tests on physicians' diagnostic thinking in variable conditions.

Abdomen, Acute↗
PubMed2003

[Hepatic perfusion CT imaging analyzed by the dual-input one-compartment model].

AIM: To improve liver-perfusion imaging by using the dual-input one-compartmental model. METHODS: Single-level dynamic computed tomography (dynamic CT) was taken at the height of the hepatic hilum after a rapid intravenous injection using 40 ml of iodinated contrast material. From the time-density curve of each pixel on CT, we calculated blood-flow rate constants of liver inflow and outflow. For inflow, two constants were calculated at arterial and portal veins. We postulated that blood flow between hepatic vessels and the hepatic parenchyma could be analyzed by using the calculated constants, and made equations for liver perfusion mapping. The perfusion images obtained by this method were compared with those made by the maximum slope method. RESULTS: We applied the method to a patient with hepatolithiasis. On dynamic CT, there was an abnormal enhancement pattern in the posterior segment of the liver. Perfusion CT images made by the dual-input one-compartment model demonstrated abnormal portal perfusion of the liver. In contrast, those made by the maximum-slope method did not represent the perfusion pattern well. CONCLUSION: The dual-input one-compartmental model makes it possible to obtain more detailed information on liver hemodynamics.

Bile Ducts, Intrahepatic↗
PubMed2003

Brain microhemorrhages detected on T2*-weighted gradient-echo MR images.

BACKGROUND AND PURPOSE: Multifocal microhemorrhages have been reported to be commonly found in the brain of patients with systemic hypertension and spontaneous brain hemorrhage. The factors associated with these lesions detected on T2*-weighted gradient-echo images were examined to determine whether these lesions serve to indicate different types of microangiopathy and to predict a patient's risk for symptomatic hemorrhage. METHODS: The study population consisted of 2164 patients who underwent 2416 consecutive brain MR imaging studies performed during 3 years. The patients with intracerebral hemorrhages due to vascular malformations, neoplasms, trauma, or intracranial surgery and those with incomplete medical records were excluded; 2019 cases were analyzed. RESULTS: The overall incidence of microhemorrhages was 9.8%, predominantly in the lentiform nucleus (n = 96), thalamus (n = 88), and cortical-subcortical region (n = 93). Presence of microhemorrhages had the highest significant correlation with history of hemorrhagic stroke (P <.0001); advancing age, hypertension, and prominent white matter hyperintensity on T2-weighted images had the next highest significant correlation. Cortical-subcortical microhemorrhages were more frequently observed in patients who had previous lobar hemorrhagic stroke (P <.005). Among 139 patients with microhemorrhages who could be clinically followed up for more than 1 month, four (2.9%) had new hemorrhagic stroke. CONCLUSION: The presence of microhemorrhages may be not only a direct marker of bleeding-prone small-vessel diseases but also an indicator of different types of microangiopathy and a predictor of further hemorrhagic stroke.

Adult↗
PubMed2003

[Whether and under what conditions FDG-PET might be cost-effective in evaluating solitary pulmonary nodules depicted on lung cancer screening in Japan].

PURPOSE: To determine whether and under what conditions fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) may be cost-effective in evaluating solitary pulmonary nodules depicted on lung cancer screening in Japan. MATERIALS AND METHODS: Three decision models for differentiating lung cancer from benign nodules were compared: CT alone, PET alone, and CT plus PET. The various paths of each strategy were dependent on variables determined from a review of the medical literature. Costs were based on Japanese health insurance. RESULTS: The prevalence of lung cancer among solitary pulmonary nodules detected on lung cancer screening was less than 10%. For this prevalence, the CT-plus-PET model was the cost-effective alternative to the CT-alone model (cost savings were yen 64,000 per patient) and provided greater accuracy (0.90 vs. 0.84). Both of these effects were the result of reducing the number of candidates who undergo unnecessary CT-guided or bronchofiberscopic biopsies or thoracotomy for a benign pulmonary nodule. CONCLUSION: The CT-plus-PET strategy is accurate and cost-effective for the characterization of solitary pulmonary nodules detected on lung cancer screening in Japan.

Cost-Benefit Analysis↗
PubMed2002

Measuring portal venous perfusion with contrast-enhanced CT: comparison of direct and indirect methods.

RATIONALE AND OBJECTIVES: Two algorithms can be used to measure portal venous perfusion (PVP) with contrast material-enhanced single-level liver computed tomography. The "direct" and "indirect" algorithms use data from the portal vein and aorta, respectively. This study compared PVP values obtained with direct and with indirect algorithms in a series of patients. MATERIALS AND METHODS: Both techniques were applied in 27 patients with cirrhosis (14 men and 13 women; mean age, 56.1 years +/- 9.4) and 18 control patients (seven men and 11 women; 52.8 years +/- 12.3). A single section through the liver was scanned after intravenous injection of ioversol (40-mL bolus; 320 mg of iodine per milliliter). RESULTS: Both techniques showed reduced PVP in patients with cirrhosis (0.63 for direct and 0.17 for indirect method) compared with control patients (1.06 and 0.26, respectively), but only the direct method agreed with physiologic expectations based on animal and human studies. In separating cirrhotic and control patients, the area under the receiver operating characteristic curve was significantly greater for the direct method (0.91 vs 0.78; P = .03). CONCLUSION: Both direct and indirect methods are feasible and distinguish well between cirrhotic and control patients, but the direct method is more physiologic and is preferable if portal venous data are available.

Algorithms↗
PubMed2002

Development of perfusion CT software for personal computers.

RATIONALE AND OBJECTIVES: The authors developed software for creating quantitative maps of arterial and portal perfusion in the upper abdominal organs on personal computers. The image quality of these perfusion computed tomographic (CT) images was visually evaluated. MATERIALS AND METHODS: In 58 patients (38 men, 20 women; mean age, 63.9 years +/- 11.9; range, 22-85 years) with various diseases of the upper abdomen, 91 single-section dynamic CT studies were obtained. The data were transferred on-line to a personal computer, and quantitative maps of arterial and portal perfusion were created by means of the maximum-slope method. Perfusion CT images were reviewed by a radiologist and a radiation technologist, and image quality was rated according to a four-category scoring system (1 = good quality, 2 = moderate, 3 = poor, 4 = images could not be created). RESULTS: Arterial perfusion CT images could be created in 81 (89%) of 91 examinations, and 74 images (81%) were scored as 1 or 2. Portal perfusion CT images could be created in 60 (68%) of 88 examinations, in which a portal trunk was included in the section, and 33 of them (38%) were scored as 1 or 2. Patient motion during dynamic CT sequences resulted in poor image quality in seven arterial and 27 portal perfusion images. CONCLUSION: Perfusion CT can combine quantitative perfusion maps with good anatomic detail in one image, although patient movement frequently degrades image quality in portal perfusion CT.

Abdomen↗
PubMed2002

Effect of contrast-enhanced computed tomography on diagnosis and management of acute abdomen in adults.

AIM: To determine the impact of computed tomography (CT) on the diagnosis and treatment plan in patients with acute abdominal pain. MATERIALS AND METHODS: A prospective study was undertaken in 125 adult patients presenting with acute abdominal pain (74 men and 51 women; 40.2 +/- 19.3 years; range, 18-92). Changes in diagnosis, gain in percentage diagnostic certainty and changes of treatment plan of the surgeons in the emergency department before and after CT were evaluated. Pre- and post-CT diagnoses were compared with the final diagnoses. RESULTS: CT findings changed the initial diagnosis in 40 (32.0%) patients. The diagnostic certainty was 58.3 +/- 22.9% before CT, and its gain after CT was 21.9 +/- 18.5 points (P < 0.0001). Post-CT diagnoses were consistent with the final diagnosis in 116 patients (92.8%), while pre-CT diagnoses were correct in 89 patients (71.2%; P < 0.0001). Initial treatment plans were changed in 31 (24.8%) patients after CT. In 57 (45.6%) patients, CT information changed diagnoses and/or treatment plans. No significant differences were observed in the diagnosis, diagnostic certainty and treatment plan among four surgeons. CONCLUSION: Contrast-enhanced CT frequently changed the clinical diagnoses with increased diagnostic certainty and the initial treatment plans.

Abdomen, Acute↗