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Biomedical subjects

Tsunehiko Nishimura

Publications and source records attributed to Tsunehiko Nishimura.

At least 109 records · Page 6Linked to original sources
PubMed2002

Detection of misery perfusion with split-dose 123I-iodoamphetamine single-photon emission computed tomography in patients with carotid occlusive diseases.

BACKGROUND AND PURPOSE: Patients with carotid occlusive disease and stage 2 cerebral hemodynamic failure, characterized by an increased oxygen extraction fraction (OEF) as measured by positron emission tomography (PET) and otherwise known as misery perfusion, have a high risk of cerebral ischemia and subsequent stroke. In clinical practice, the detection of patients with misery perfusion through the use of widely available, noninvasive, and cost-effective modalities such as single-photon emission computed tomography (SPECT) is extremely important. METHODS: We evaluated the relationships between the regional hemodynamic status of cerebral circulation, measured with split-dose [123I] N-isopropyl-p-iodoamphetamine SPECT (123I-IMP SPECT) and an acetazolamide challenge, and hemodynamic parameters, including OEF measured with PET, in 27 patients with both unilateral and bilateral carotid occlusive diseases. RESULTS: A significant negative correlation was found between the SPECT-measured cerebrovascular reserve after acetazolamide administration and both the PET-measured OEF and cerebral blood volume. Neither the cerebrovascular reserve nor the cerebral blood flow index, when expressed as a SPECT-measured cerebrum-to-cerebellum ratio, was useful for detecting lesions with an elevated OEF. However, a combination of the cerebrovascular reserve and cerebral blood flow index showed high sensitivity, specificity, and positive predictive value for the detection of misery perfusion. CONCLUSIONS: Our study suggests that split-dose 123I-IMP SPECT with an acetazolamide challenge could be useful for screening patients with misery perfusion in carotid occlusive diseases.

Acetazolamide↗
PubMed2002

Magnetic resonance perfusion-weighted imaging of acute cerebral infarction: effect of the calculation methods and underlying vasculopathy.

BACKGROUND AND PURPOSE: Various calculation methods are available to estimate the transit-time on MR perfusion-weighted imaging (PWI). Each method may affect the results of PWI. Steno-occlusive disease in the parent vessels is another factor that may affect the results of the PWI. The purpose of this study was to elucidate the effect of the calculation methods and underlying vasculopathy on PWI. METHODS: From a pool of 113 patients who had undergone PWI during the study period, a total of 12 patients with nonlacunar ischemic strokes who were scanned within 24 hours after onset of symptom were selected for the study. The patient population consisted of 6 patients who had extracranial internal carotid artery stenosis (>70%) and 6 individuals without stenosis. Seven different postprocessing methods were evaluated: first moment, ratio of area to peak, time to peak (TTP), relative TTP, arrival time, full-width at half-maximum, and deconvolution methods. Follow-up MR or CT images were used to determine the areas that evolved into infarcts, which served as the gold standard. Sensitivity and specificity of each transit time technique were calculated. RESULTS: Calculation methods with high sensitivity were the first moment (sensitivity, 74%), TTP (sensitivity, 77%), and deconvolution methods (sensitivity, 81% to 94%). Between the 2 groups with and without internal carotid artery stenosis, the specificity of most of the techniques was lower in the internal carotid artery stenosis group. The first moment and deconvolution methods maintained relatively high specificity even in the stenosis group. CONCLUSIONS: The calculation technique and presence of underlying vasculopathy have a direct impact on the results of PWI. The methods with high sensitivity even in the presence of steno-occlusive disease were the first moment and deconvolution methods with arterial input function derived from the peri-infarct arteries; the deconvolution method was the superior choice because of higher lesion conspicuity.

Acute Disease↗
PubMed2002

Management of pneumothorax after percutaneous CT-guided lung biopsy.

OBJECTIVES: To evaluate the efficacy of simple aspiration of air from the pleural space to prevent increased pneumothorax and to avoid chest tube placement in cases of pneumothorax following CT-guided lung biopsy. DESIGN: Observational. MATERIALS AND METHODS: One hundred thirty-four consecutive percutaneous needle lung biopsies using real-time CT fluoroscopy guidance formed the basis of our study. All patients that demonstrated moderate or severe pneumothorax on postbiopsy chest CT images underwent percutaneous manual aspiration regardless of symptoms while on the CT scanner table. Correlation between the incidence of pneumothorax after biopsy and many factors (i.e., gender, age, number of pleural passes, presence of emphysema, lesion size, and lesion depth) were determined, and management of each case of biopsy-induced pneumothorax was reviewed. RESULTS: Postbiopsy pneumothorax occurred in 46 of 134 procedures (34.3%). Twenty of the 46 patients were treated by manual aspiration, while 26 patients were simply observed. In 43 of the 46 pneumothoraces (93.5%), the pneumothorax resolved completely on follow-up chest radiographs without requiring tube placement. Only three patients (2.2% of the entire series; 6.5% of those who had pneumothorax develop) required chest tube placement. The risk of pneumothorax significantly increased with lesion size and depth. CONCLUSION: Results of our nonprospective, nonrandomized study suggest that percutaneous manual aspiration of biopsy-induced pneumothorax performed immediately after biopsy may prevent progressive pneumothorax and subsequent chest tube placement.

Adolescent↗
PubMed2002

Effects of prostaglandin E(1) injection through the superior mesenteric artery on the hemodynamics of hepatocellular carcinoma.

OBJECTIVE: The purpose of our study was to assess the effects of portal blood flow on contrast enhancement in hepatocellular carcinoma lesions on CT hepatic arteriography. SUBJECTS AND METHODS: We examined 43 tumors in 39 patients who simultaneously underwent CT during arterial portography and CT hepatic arteriography for examination of liver tumors and then CT hepatic arteriography with prostaglandin E(1) injection via the superior mesenteric artery. All lesions pathologically confirmed to be hepatocellular carcinomas exhibited portal perfusion defects on CT during arterial portography. Changes in CT attenuation, size, and shape of liver tumors visualized on CT hepatic arteriography after intraarterial injection of prostaglandin E(1) were studied. In addition, changes in CT attenuation of the liver parenchyma surrounding the tumor were measured. RESULTS: The CT attenuation increased significantly after injection of prostaglandin E(1) in 91% (39/43) of the lesions (mean increase from 176.4 to 206.6 H; p = 0.0006, paired t test). The size and shape of the enhanced area generally did not change. The CT attenuation of the liver parenchyma surrounding each liver tumor significantly decreased in 58% (25/43) of the hepatocellular carcinoma lesions (mean decrease from 94.8 to 92.0 H; p = 0.0166, paired t test) and lesion conspicuity increased in 91% (39/43) of the tumors. CONCLUSION: Lesion conspicuity on CT hepatic arteriography between hepatocellular carcinoma and the surrounding liver parenchyma increased because of greater portal perfusion after the prostaglandin E(1) injection.

Aged↗
PubMed2002

Embolization of the right gastric artery before hepatic arterial infusion chemotherapy to prevent gastric mucosal lesions: approach through the hepatic artery versus the left gastric artery.

OBJECTIVE: The purpose of our study was to evaluate whether the hepatic artery or the left gastric artery is the better route of approach for selective embolization of the right gastric artery before hepatic arterial infusion chemotherapy using a port-catheter system. SUBJECTS AND METHODS: Eighty-six patients (56 men, 30 women; mean age, 62.1 years) with unresectable advanced liver cancer underwent percutaneous implantation of a port-catheter system. In the 75 patients who had not undergone gastrectomy, right gastric artery embolization was performed before port-catheter system placement to prevent gastric mucosal lesions. In 43 patients, the approach for embolization was through a microcatheter inserted from the hepatic artery site, and in the remaining 32 patients, the approach was from the left gastric artery. The success rates of these two groups were compared. RESULTS: Embolization was successfully accomplished at the first attempt in 72.1% of the 43 patients in whom the microcatheter was inserted from the hepatic artery site. In contrast, in 93.8% of 32 patients, embolization was successfully performed through the left gastric artery. The success rate of embolization was significantly higher in the latter group (p = 0.0173, chi-square test). A second attempt in which the catheter was redirected to another approach, performed on the same day in a majority of patients, resulted in successful embolization in an additional eight patients, with a final success rate of 92.0%. CONCLUSION: Embolization of the right gastric artery using microcoils through a microcatheter advanced through the left gastric artery may be the preferred method for the preparation of repeated hepatic artery infusion.

Angiography↗
PubMed2002

Using n-butyl cyanoacrylate and the fixed-catheter-tip technique in percutaneous implantation of a port-catheter system in patients undergoing repeated hepatic arterial chemotherapy.

OBJECTIVE: The purpose of our study was to evaluate the usefulness of adding n-butyl cyanoacrylate to microcoils to fix the catheter tip in percutaneous implantation of a port-catheter system for hepatic arterial-infusion chemotherapy. SUBJECTS AND METHODS: Ninety-three patients (64 men and 29 women; age range, 38-83 years; mean age, 62.2 years) with unresectable advanced liver cancer underwent percutaneous implantation of a port-catheter system with the catheter tip fixed at the gastroduodenal artery with microcoils and a mixture of n-butyl cyanoacrylate and iodized oil. The rates of successful implantation and complications closely associated with this technique and management of the complications were reviewed. RESULTS: Percutaneous port-catheter placement was successfully performed in all patients. However, in eight patients, complications occurred: hepatic arterial obstruction (n = 5, 5.4%); catheter dislocation (n = 2, 2.2%); recanalization of the gastroduodenal artery (n = 1, 1.1%); or movement of n-butyl cyanoacrylate (n = 1, 1.1%). In five of the eight patients with complications, hepatic arterial-infusion chemotherapy was continued either after observation of the patient to ensure that stability had been established or after treatment using comparatively easy interventional techniques. In three (3.2%) of the 93 patients, planned hepatic arterial-infusion chemotherapy could not be performed because of complications associated with the technique. CONCLUSION: Fixation of the catheter tip in the gastroduodenal artery using a combination of microcoils and a mixture of n-butyl cyanoacrylate and iodized oil is a useful and safe technique in percutaneous port-catheter placement for repeated hepatic arterial infusion chemotherapy.

Adult↗
PubMed2002

(123)I- or (125)I-metaiodobenzylguanidine visualization of brown adipose tissue.

UNLABELLED: (123)I-Metaiodobenzylguanidine (MIBG) accumulations that do not correspond to any tumor are observed occasionally on the medial aspect of the upper back or shoulder of children. The true nature of such accumulations is unknown, and we hypothesized that they represent interscapular brown adipose tissue (IBAT) visualized by scintigraphy. METHODS: Wistar rats (7 wk old) received MIBG labeled with (123)I or (125)I. Autoradiography was performed, and concentrations of the tracer in the interscapular subcutaneous tissue were identified histopathologically. The effects of 6-hydroxydopamine, reserpine, and beta 3-adrenergic receptor agonist (CL316,243) on the accumulation were investigated to elucidate the mechanism of uptake into BAT. RESULTS: Autoradiography showed well-defined distinct accumulation in the subcutaneous tissue on the upper back, and hematoxylin-eosin and anti-uncoupling protein 1 antibody staining confirmed that it was BAT. The percentage injected dose per gram in BAT was as high as that in the heart and was quite different from the concentration in white adipose tissue. Preadministration of 6-hydroxydopamine or reserpine resulted in lower MIBG concentrations in BAT. Activation of the beta 3-adrenergic receptor accelerated the washout of MIBG in BAT and caused an increase in concentration in white adipose tissue. CONCLUSION: MIBG accumulates in the adrenergic nervous system in BAT, and IBAT is distinguished from the surrounding white adipose tissue. To our knowledge, BAT has not been visualized previously. We showed that MIBG scintigraphy might be suitable for the investigation of BAT and treatment of human obesity.

3-Iodobenzylguanidine↗
PubMed2002

Proton chemical shift imaging in pick complex.

BACKGROUND AND PURPOSE: Pick complex (PC) is the name given to a group of diseases comprising Pick disease and its variations, all of which have a large degree of pathologic and clinical overlap. Because of this overlap, the observation of neuropathologic changes in vivo is difficult, although these changes play important roles in the criteria used for classification. The purpose of this study was to evaluate changes in brain metabolism in PC with proton chemical shift imaging ((1)H-CSI). METHODS: Nine patients with PC (three each with frontotemporal dementia, corticobasal degeneration [CBD], and primary progressive aphasia [PPA]) and five healthy subjects underwent (1)H-CSI. Volumes of interest were selected at the level of the basal ganglia by using a spin-echo sequence (TR/TE, 2000/13). Peak areas and ratios of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) were calculated in voxels in the basal ganglia and perisylvian regions. RESULTS: Reduced NAA/Cho ratios were observed in the right basal ganglia of the patients with PC. In patients with CBD or PPA, low NAA/Cr values were detected in the right perisylvian region. CONCLUSION: In PC, (1)H-CSI decreased NAA values in a wide area. Significantly reduced NAA levels in the right hemisphere in patients with PC suggests a neurodegenerative change and may reflect cases in which the right hemisphere is dominantly affected, compared with the left hemisphere. (1)H-CSI provided information that could not be obtained with other imaging techniques. Thus, (1)H-CSI may provide useful information for understanding the pathologic process underlying PC.

Adult↗
PubMedDate not supplied

Gunther tulip inferior vena cava filter placement during treatment for deep venous thrombosis of the lower extremity.

PURPOSE: To evaluate the efficacy and safety of Gunther tulip retrievable vena cava filter (GTF) implantation to prevent pulmonary embolism during intravenously administered thrombolytic and anticoagulation therapy and interventional radiological therapy for occlusive or nonocclusive deep venous thrombosis (DVT) of the lower extremity. METHODS: We evaluated placement of 55 GTFs in 42 patients with lower extremity DVT who had undergone various treatments including those utilizing techniques of interventional radiology. RESULTS: Worsening of pulmonary embolism in patients with existing pulmonary embolism or in those without pulmonary embolism at the time of GTF insertion was avoided in all patients. All attempts at implantation of the GTF were safely accomplished. Perforation and migration experienced by one patient was the only complication. Mean period of treatment for DVT under protection from pulmonary embolism by the GTF was 12.7 +/- 8.3 days (mean +/- SD, range 4-37 days). We attempted retrieval of GTFs in 18 patients in whom the venous thrombus had disappeared after therapy, and retrieval in one of these 18 cases failed. GTFs were left in the vena cava in 24 patients for permanent use when the DVT was refractory to treatment. CONCLUSION: The ability of the GTF to protect against pulmonary embolism during treatment of DVT was demonstrated. Safety in both placement and retrieval was clarified. Because replacement with a permanent filter was not required, use of the GTF was convenient when further protection from complicated pulmonary embolism was necessary.

Adolescent↗
PubMedDate not supplied

Usefulness and limitation of manual aspiration immediately after pneumothorax complicating interventional radiological procedures with the transthoracic approach.

The goal of this study was to evaluate the efficacy of simple aspiration of air from the pleural space to prevent increased pneumothorax and avoid chest tube placement in cases of pneumothorax following interventional radiological procedures performed under computed tomography fluoroscopic guidance with the transthoracic percutaneous approach. While still on the scanner table, 102 cases underwent percutaneous manual aspiration of a moderate or large pneumothorax that had developed during mediastinal, lung, and transthoracic liver biopsies and ablations of lung and hepatic tumors (independent of symptoms). Air was aspirated from the pleural space by an 18- or 20-gauge intravenous catheter attached to a three-way stopcock and 20- or 50-mL syringe. We evaluated the management of each such case during and after manual aspiration. In 87 of the 102 patients (85.3%), the pneumothorax had resolved completely on follow-up chest radiographs without chest tube placement, but chest tube placement was required in 15 patients. Requirement of chest tube insertion significantly increased in parallel with the increased volume of aspirated air. When receiver-operating characteristic curves were applied retrospectively, the optimal cutoff level of aspirated air on which to base a decision to abandon manual aspiration alone and resort to chest tube placement was 670 mL. Percutaneous manual aspiration of the pneumothorax performed immediately after the procedure might prevent progressive pneumothorax and eliminate the need for chest tube placement. However, when the amount of aspirated air is large (such as more than 670 mL), chest tube placement should be considered.

Adult↗
PubMedDate not supplied

Evaluation of retrievability of the Gunther tulip vena cava filter.

PURPOSE: To evaluate the feasibility and safety of withdrawal of a Gunther tulip retrievable vena cava filter (GTF). METHODS: Between June 2001 and December 2005, at our institution 86 GTFs were implanted for temporary caval filtration in 59 patients (37 women, 22 men; mean age 59.3 years, range 18-87 years). For GTFs retrieved thereafter, we retrospectively reviewed the following parameters: rate of success in retrieval, degree of trapped thrombus in the filter, and complications during retrieval. RESULTS: Worsening of or new development of pulmonary embolism after filter implantation did not occur in any patient. Of the 86 GTFs implanted, retrieval of 80 was attempted. Among those 80 filters, 77 (96%) were successfully retrieved (with the standard method, n = 72; with the modified method, n = 5) without any complication. The period of implantation of the retrieved filters was 13.4 +/- 4.2 days. In the 5 filters that were filled to a height of > or = 1/4 with trapped thrombus, retrieval was performed after attempts were made to decrease trapped thrombi. In addition, a temporary filter or another GTF was temporarily placed at the cephalad level of the GTF during this removal procedure. CONCLUSION: GTFs can be retrieved in the majority of cases. Even when encountering situations in which the filter could not be removed using the standard method, withdrawal was possible in a high frequency of cases through various trials using modified methods.

Adult↗
PubMedDate not supplied

Identification of exercise-induced left ventricular systolic and diastolic dysfunction using gated SPECT in patients with coronary artery disease.

BACKGROUND: We investigated whether poststress left ventricular dysfunction in patients with coronary artery disease may be confirmed at 30 minutes after exercise using newly modified quantitative gated single photon emission computed tomography (QGS) software that can evaluate systolic and diastolic function. METHODS AND RESULTS: In this study 28 control subjects, 26 patients with angina pectoris (AP), and 27 patients with old myocardial infarction (MI) who had undergone revascularization were included. Same-day exercise/rest gated technetium 99m tetrofosmin single photon emission computed tomography was performed. QGS was used with a temporal resolution of 32 frames per R-R interval, and a left ventricular volume curve was reconstructed. From the fitted volume curve and its first derivative curve, we derived the ejection fraction (EF), peak ejection rate (PER), peak filling rate (PFR), and time to PFR (TPFR). In patients with AP and MI, the values for EF, PER, and PFR were lower after stress than at rest. TPFR was significantly prolonged in patients with MI after stress. In control subjects, EF, PER, PFR, and TPFR were not changed. CONCLUSIONS: Modified QGS software successfully indicated the changes in systolic and diastolic function. In patients with AP and MI, poststress systolic and diastolic dysfunction was identified 30 minutes after exercise.

Angina Pectoris↗
PubMedDate not supplied

Prognostic value of I-123 15-(p-iodophenyl)-3-(R,S) methylpentadecanoic acid myocardial imaging in patients with known or suspected coronary artery disease.

BACKGROUND: Although iodine 123 15-(p-iodophenyl)-3-(R , S) methylpentadecanoic acid (BMIPP) can assess abnormal utilization of fatty acid in the diseased myocardium, the prognostic value of BMIPP imaging at rest in patients with known or suspected coronary artery disease (CAD) remains unclear. METHODS AND RESULTS: A total of 270 patients were included by a retrospective search of the existing databases of 4 institutions. In addition to hard events, consisting of cardiac death and nonfatal myocardial infarction, any significant events including death, nonfatal myocardial infarction, coronary revascularization, heart failure, and unstable angina were assessed. During a median follow-up of 3.9 years, 33 patients had significant events, among whom 10 had hard events. Kaplan-Meier survival estimates revealed a hard event-free survival rate of 98% at 3 years in patients with a BMIPP defect score lower than 5 but 93% in those with a defect score of 5 or greater ( P = .03). With regard to significant events, the analysis showed an event-free survival rate of 92% at 3 years in patients with a BMIPP defect score lower than 5 but 80% in those with a defect score of 5 or greater ( P = .0003). CONCLUSIONS: These results indicate that resting BMIPP imaging has prognostic value and may have a role in the risk stratification of patients with known or suspected CAD.

Adult↗
PubMedDate not supplied

Characteristics of regional myocardial stunning after exercise in gated myocardial SPECT.

BACKGROUND: A number of studies have demonstrated prolonged left ventricular (LV) global dysfunction after exercise-induced ischemia in gated myocardial single photon emission tomography (SPECT) as a manifestation of exercise-induced stunning. This study investigated the residual effects of exercise on postexercise LV regional function and its implications on the detection of stunning in gated SPECT. METHODS AND RESULTS: Fifty-three subjects with known or suspected coronary artery disease and 10 control subjects underwent myocardial SPECT according to a same-day exercise-rest protocol. Both postexercise and resting images were gated and acquired 1 hour after injection of technetium 99m tetrofosmin. The LV global ejection fraction and segmental systolic wall thickening were quantitated with the use of an automatic program. Segmental perfusion was assessed semiquantitatively on summed nongated tomograms. Wall thickening index (WTI), the ratio of systolic wall thickening of a segment to that of a corresponding control segment, was significantly lower after exercise than at rest in the reversible defect (RD) segments (0.66 +/- 0.24 vs 0.78 +/- 0.24; P <.0001). In patients with exercise-induced ischemia, the difference in WTI between rest and after exercise was significantly greater in the RD segments, which represented ischemia, than in the non-RD segments. Postexercise WTIs were not different from the resting values in subjects with no perfusion abnormalities or who had fixed defects (infarction). Significant postexercise dysfunction was present in 44% of the RD segments, compared with 5% of the normal and 3% of the fixed defect segments. Postexercise segmental dysfunction was correlated with the segmental reversibility score, the difference in defect scores between exercise and rest images (n = 82, Spearman rank correlation coefficient = -0.78, P <.0001). Among 19 patients with ischemia, 9 (47%) exhibited concurrent segmental and global dysfunction, but segmental dysfunction persisted in the absence of global dysfunction in 4 additional patients (21%). CONCLUSIONS: Significant postexercise LV regional dysfunction, consistent with the concept of stunning, occurs in the region of severe ischemia. The incidence and magnitude of regional stunning are determined by the severity of ischemia. For the detection of stunning in gated SPECT, LV regional dysfunction may be more sensitive than global dysfunction.

Adult↗
PubMedDate not supplied

Detection of viable myocardium with p-iodophenyl-9-(R,S)-methylpentadecanoic acid in ischemic rat myocardium.

BACKGROUND: The methyl-branched free fatty acid analog 15-(p-iodophenyl)-9-(R,S)-methylpentadecanoic acid (9MPA) is metabolized more rapidly than 15-(p-iodophenyl)-3(beta)-(R,S)-methylpentadecanoic acid. This study investigates whether myocardial ischemic injury to beta-oxidation and viable myocardium can be detected with the use of 9MPA in a rat myocardial ischemia model. METHODS AND RESULTS: In the acute study the left coronary arteries were occluded for 15 or 45 minutes and then reperfused; the rats were killed after 2 hours. Iodine 125 and iodine 123 9MPA was injected 60 minutes (delayed images) and 3 minutes (early images), respectively, before the rats were killed. In the subacute study the left coronary arteries were either occluded for 45 minutes and then reperfused or occluded and not reperfused. One week later, I-125 and I-123 9MPA was injected 60 minutes and 3 minutes, respectively, before the rats were killed. The distribution of 9MPA was examined with the use of dual-tracer autoradiography. In the acute study the delayed images showed a higher uptake in viable regions at risk than in normal areas and nonviable regions. In the subacute study a difference in uptake between viable regions at risk and normal areas was visible on the early images, but this difference disappeared on the delayed images. CONCLUSIONS: 9MPA is a useful tracer for detecting viable regions of ischemic myocardium during acute and subacute disease stages.

Animals↗