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Biomedical subjects

Isamu Narabayashi

Publications and source records attributed to Isamu Narabayashi.

34 records · Page 2Linked to original sources
PubMed2003

Stereotactic radiosurgery (SRS) for multiple metastatic brain tumors: effects of the number of target tumors on exposure dose in normal brain tissues.

BACKGROUND: This study was carried out to clarify the practical limit of the number of stereotactic radiosurgery (SRS)-targeted tumors based on the irradiation dose of normal brain tissues. METHODS: Twenty-five patients with multiple brain metastases who received SRS from October 1998 to May 2002 were enrolled in the study. In each patient, the treatment options were thoroughly studied before deciding upon a course of treatment. The number of irradiated targets was increased one by one until all of the targets were included in a treatment plan. Given a surface dose of 25 Gy, we calculated the dose volume histogram (DVH) for the entire brain in each treatment plan and compared it with those of other treatment plans. Ultimately, only 5 of the 25 patients received irradiation for all of their tumors; the others received selective irradiation targeting only those tumors that were causing symptoms. RESULTS: When the number of targets increased, the DVH curve shifted to the right. The volume of the brain irradiated at a dose of 5 Gy or higher was 25.7% or less for 4 or fewer targets, 45.7% for 5-6 targets, 81.0% for 7-8 targets and 100% for 9-11 targets. When the number of the targets exceeded 8, more than 50% of the entire brain was irradiated at levels of at least 8.7 Gy. The dose distribution became very complex as the number of targets increased. Although the survival time of the group in which tumors were selectively targeted was longer than that in the group in which all tumors were irradiated, the difference between the two groups was not statistically significant ( P = 0.2537). CONCLUSION: In SRS for multiple brain metastases, risks of both acute and late sequelae may increase because the exposure dose to normal brain tissues increases with increased numbers of target tumors. Dose distribution becomes more complex according to the increase in the number of targets. Based on our DVH curves, we conclude that the exposure dose to normal brain tissues is acceptable when the number of targets is less than 7. Importantly, our study also reveals that it may not be necessary or desirable to irradiate all metastatic tumors.

Adult↗
PubMed2003

Preoperative simulation of vascular anatomy by three-dimensional computed tomography imaging in laparoscopic gastric cancer surgery.

BACKGROUND: Treatment of early gastric cancer may be an ideal application for laparoscopic surgery. But laparoscopic surgery has various limitations derived from the lack of tactile feedback and a two-dimensional display of the operative field. So, laparoscopic surgery is technically challenging and requires a more detailed understanding of local anatomy than conventional open surgery does. The purpose of this study was to evaluate the value of three-dimensional computed tomography imaging in the preoperative simulation of laparoscopic gastric cancer surgery. STUDY DESIGN: Multidetector-row helical CT was performed preoperatively in 49 patients who underwent laparoscopic gastric cancer surgery. Scanning was initiated approximately 20 seconds after an intravenous injection of 100 mL of contrast material at 5 mL/second. Three-dimensional CT images were reconstructed using the volume-rendering technique. RESULTS: 3D-CT imaging depicted the stomach, arterial, and venous anatomy and was able to identify important vascular variants. Preoperative information concerning the right gastric artery led us to the site of its branching and facilitated dissection of suprapyloric lymph nodes. The left gastric artery furnishing the aberrant left hepatic artery was successfully revealed and this information enabled us to avoid accidental hemorrhage and ischemic liver damage. Preoperative confirmation of the drainage routes of the left gastric vein was also useful in accomplishing secure lymphadenectomy. CONCLUSIONS: 3D-CT imaging provides a vascular "road map," which is critical for surgical guidance, and prevents the risks involved in surgery. Preoperative 3D-CT imaging may be an informative device to overcome the disadvantages of laparoscopic gastric cancer surgery.

Computer Simulation↗
PubMed2003

Three-dimensional CT angiography of the hepatic artery: use of multi-detector row helical CT and a contrast agent.

The administration of a contrast agent to obtain optimal images at three-dimensional computed tomographic (CT) angiography of the hepatic artery by using multi-detector row helical CT was investigated. Three-dimensional CT angiographic images were evaluated visually, and quantitative evaluation was performed by measuring the postcontrast CT number of the aorta. The injection rate of 5 mL/sec was significantly superior to that of 4 mL/sec in both evaluations. At administration of a contrast agent with 300 or 350 milligrams of iodine per milliliter, there were no significant differences in either evaluations. The preferable injection rate to obtain sufficient three-dimensional CT angiographic data was 5 mL/sec.

Aged↗
PubMed2003

[Clinical application of three-dimensional imaging with multislice CT for laparoscopic colorectal surgery].

PURPOSE: Laparoscopic colorectal surgery, while minimally invasive, is a complicated technique. Therefore, prior to this surgery, it is important to determine the anatomical information of colorectal cancer. MATERIALS AND METHODS: Fifty-eight cases of patients with a confirmed diagnosis of colon cancer [caecal (n = 4), ascending colon (n = 6), transverse colon (n = 7), descending colon (n = 2), sigmoid colon (n = 22), and rectal (n = 17) cancer] were evaluated using multislice CT before laparoscopic surgery. CT examination was performed in an air-filled colorectum by colon fiberscopy. Contrast-enhanced images on multislice CT were obtained at arterial and venous phases. All images were reviewed on a workstation, and three-dimensional (3D) images of vessels, colorectum, cancer, and swollen lymph nodes were reconstructed by volume rendering and fused (integrated 3D imaging). We evaluated the usefulness of integrated 3D imaging with multislice CT for laparoscopic colorectal surgery. RESULTS: Integrated 3D imaging demonstrated clearly the distribution of arteries feeding the colorectal cancer and the anatomical location of colorectal cancer and arterial and venous systems. Moreover, measurement of the distance between the aortic bifurcation and the origin of the inferior mesenteric artery and that between the base of the inferior mesenteric artery and the origin of the left colic artery on integrated 3D imaging contributed to safe, prompt ligation of the vessels and excision of lymph nodes. CONCLUSION: Integrated 3D imaging with multislice CT was useful for simulation of laparoscopic colorectal surgery.

Colorectal Neoplasms↗
PubMed2003

[Effect of contrast material pushed with saline solution using dual injection on enhancement of aorta, portal vein, and liver parenchyma in multislice CT of the liver].

We evaluated the effect of the enhancement value of the abdominal aorta, portal vein, and liver parenchyma by the saline flush technique. One hundred eight patients who underwent multislice CT of the liver were randomly divided into four groups: 100 ml of contrast material (Iomeprol 300 mgI/ml or 350 mgI/ml) only and 100 ml of contrast material (300 mgI/ml or 350 mgI/ml) flushed with 50 ml of saline solution at a rate of 5 ml/sec. The saline flush technique demonstrated statistically significantly greater portal enhancement. Therefore, we consider that this technique contributes to the visualization of three-dimensional CT portography.

Adult↗
PubMed2003

[Three-dimensional angiography of arteries and veins around the stomach using multislice CT for preoperative simulation of laparoscopic gastric cancer surgery: trial of multiphase fusion method].

Postcontrast CT scanning using multislice CT was performed for 20 patients with gastric cancer. Three-dimensional (3D) CT angiography of the arterial and venous phases was reconstructed using the volume-rendering technique and then fused. 3D-CT angiography showed the arteries and veins around the stomach, and multiphase fusion imaging was able to demonstrate clearly and three-dimensionally the gastric vascular anatomy. In conclusion, the multiphase fusion image was considered to be useful in the preoperative simulation of laparoscopic gastric cancer surgery.

Aged↗
PubMed2002

Present diagnostic strategies for acute pulmonary thromboembolism; results of a questionnaire in a retrospective trial conducted by the Respiratory Nuclear Medicine Working Group of the Japanese Society of Nuclear Medicine.

The aim of this study is to re-evaluate and clarify the diagnostic role of ventilation/perfusion lung scintigraphy in Japan, now that single-detector-row helical CT and multidetector-row CT are available in clinical practice. The Respiratory Nuclear Medicine Working Group of the Japanese Society of Nuclear Medicine distributed a questionnaire to institutions in Japan equipped with scintillation cameras as of September 2001. Of 1,222 institutions, 239 returned effective answers (19.6%). The most frequent combination for initial diagnosis of acute pulmonary thromboembolism was chest radiography, perfusion lung scintigraphy, and contrast-enhanced CT (111 institutions, 46.4%). The questionnaire revealed that the validity and usage of perfusion lung scintigraphy and those of contrast-enhanced CT were equivalent in the present clinical situation. On the other hand, the diagnostic value of ventilation lung scintigraphy in suspected pulmonary thromboembolism has not been established in Japan. Even though contrast-enhanced CT is widely used in Japan, perfusion lung scintigraphy is still required to determine disease severity and monitor its progress.

Acute Disease↗
PubMed2002

Long-term outcome of a residual scar from myocardial infarction after coronary artery bypass grafting: a 100-month study using myocardial perfusion scintigraphy.

The prognosis for patients with a residual scar from myocardial infarction (MI) after coronary artery bypass grafting surgery (CABG) has not been fully evaluated, so the present study retrospectively evaluated such patients with stress myocardial single photon emission computed tomography (SPECT) at 100 months after CABG. The study group consisted of 24 subjects (23 males, 1 female; mean age, 59+/-9 years) in whom CABG had been performed more than 100 months (mean follow-up period 135+/-25 months) previously. The 24 subjects were classified into 3 groups according to their summed stress score (SSS) and summed reversibility score (SRS) in the early period after CABG. Eight subjects with MI (SSS> or =2 and SRS<2) were classified into the group MI, 8 subjects with ischemic myocardium (SSS> or =2 and SRS> or =2) was classified into the group RE, and 8 subjects with normal perfusion (SSS<2 and SRS<2) was classified into group N. None of the subjects in group MI required revascularization. Cardiac events occurred in 4 of the group RE patients and all required revascularization. As to the SPECT scoring system, the long-term SSS of group MI (6.4+/-3.1) was not different from that in the early periods (4.3+/-4.0; NS). However, the long-term SSS values of group RE (8.8+/-6.2) were significantly greater than those soon after CABG (3.4+/-1.8; p=0.03). In group N, there was also no difference in the SSS values between the early period (0.3+/-0.5) and the long-term period (0.0+/-0.0; NS). Patients with a residual scar from MI in the early period after CABG did not worsen over a period of 100 months. Moreover, there was no significant difference in the SPECT score in the segment with the residual scar in the short or long term after CABG. However, the extent of reversibility was directly associated with the presence of clinical events. Therefore scintigraphic imaging remains an important and clinically relevant risk stratification tool. Stress myocardial SPECT, early after CABG, can be used to predict the possibility of future cardiac events or the need for revascularization.

Aged↗
PubMed2002

CD36 genotype and long-chain fatty acid uptake in the heart.

Homozygous or compound heterozygous mutation of the CD36 gene (CD36-/-) in humans results in severe defects of the uptake of long-chain fatty acids (LCFAs) in the heart. Because the effect of a single mutation of this gene (CD36+/-) on the LCFA uptake is not known, it was evaluated in 29 subjects with the CD36 wild-type gene (WT) (6 healthy subjects, 10 patients with heart disease), CD36+/- (4 healthy subjects, 5 patients) and CD36-/- (4 patients). The CD36 genotype was identified in the coding region of genomic DNA, and the expression of CD36 protein was examined by flow cytometry after staining with monoclonal anti-CD36 antibody. The LCFA uptake in the heart was assessed as the radioactivity accumulation ratio of heart to mediastinum after intravenous administration of iodine-123 15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid (H/M ratio). The H/M ratios in WT, CD36+/- and CD36-/- were 2.28 +/- 0.10, 1.90 +/- 0.06 and 1.40 +/- 0.11, respectively (p < 0.0001, among groups). The H/M ratio between healthy subjects and patients with heart disease for WT and CD36+/- did not differ significantly (ie, those of WT and CD36+/- in healthy subjects and patients were 2.29 +/- 0.08 vs 2.27 +/- 0.12 and 1.90+/- 0.07 vs 1.89 +/- 0.05, respectively). Not only CD36-/- but also CD36+/- resulted in a significant reduction of the LCFA uptake in the heart independent of heart disease, suggesting genotype dependency and that CD36 might be a fundamental determinant of myocardial LCFA uptake.

Adult↗
PubMed2002

Chordoma in the sella turcica.

A 75-year-old man presented with a rare case of chordoma in the sella turcica of the skull base. He had been treated for hypertension and chronic renal failure since 1990. Computed tomography detected a tumor in the sella turcica in 1994, but the patient had no clinical complaints and the serum pituitary hormone levels were normal. He died of disseminated intravascular coagulation, myocardial infarction, pulmonary infection, and multiple cerebral infarctions in 2000. At autopsy, the tumor in the sella turcica was 3.1 cm in greatest diameter and had compressed the pituitary gland posteriorly. Histological examination found oval cells and vacuolated short spindle-shaped cells which showed morphological changes similar to myxoma cells. The tumor was lobulated by narrow connective tissues. The tumor did not contain any cartilaginous tissue components, and was stained positively for epithelial membrane antigen but negatively for S-100 protein. The final diagnosis was chordoma. There was no association between the tumor and the cause of death.

Aged↗
PubMed2002

[A case of effective bisphosphonate therapy for bone metastasis from breast cancer with multiorganic metastases].

A 50-year-old woman with a past history of breast cancer was referred to our department of radiology for detailed examination after abnormal shadows on chest x-ray were detected following a routine medical examination. After lung biopsy via thoracotomy, segmental resection of the lung was performed and mediastinal lymph nodes were dissected. A histopathological diagnosis of breast cancer with lung metastasis and mediastinal lymph-node metastases was made. Later, the patient complained of pain in the left lower extremity. A diagnosis of a left tibial metastasis was made according to bone scintigraphy and MRI. Radiation therapy at 50 Gy was then initiated. Chemotherapy and hormone therapy combined with bisphosphonate therapy (Bisphonal, once in 2 weeks), was also begun. During the treatment, the patient had multiple organ metastases including multiple brain metastases, and metastases to submental lymph nodes and the left adrenal gland. However, her bone metastasis was limited to the left tibial bone and no other bone lesions were detected by bone scintigraphy and MRI. She did not experience adverse effects from the bisphosphonate therapy. We consider that the inhibition of extension and further metastases of the tibial bone metastasis noted in this patient reflected the efficacy of bisphosphonate therapy, and that bisphosphonate therapy might become an essential treatment in patients with bone metastasis of breast cancer.

Adenocarcinoma↗
PubMed2002

Ectopic thymus presenting as neck mass.

A 3-month-old girl presented with an asymptomatic soft tissue mass in the right neck. Her preoperative data were normal. CECT of the neck showed a 3-cm solid mass with homogeneous mild enhancement without mass effect. CECT of the thorax showed a normal thymus. MR images showed a right submandibular mass with signal intensity identical to that of the mediastinal thymus. Although it was difficult to make a correct preoperative diagnosis, surgical microscopic examination demonstrated normal thymic tissue. Because ectopic thymus can occasionally present with life-threatening symptoms, and malignant transformations have been documented, complete excision of cervical ectopic thymus was advocated.

Choristoma↗
PubMedDate not supplied

Comparative study of quantitative blood pool SPECT imaging with 180 degrees and 360 degrees acquisition orbits on accuracy of cardiac function.

BACKGROUND: Quantitative blood pool single photon emission computed tomography (SPECT) (QBS) can measure ejection fraction (EF) and volumes from gated blood pool single photon emission tomography (GBPS) working in fully automatic mode in 3-dimensional space. The effects of 180 degrees and 360 degrees data acquisition in GBPS have not been fully evaluated. This study compares the accuracy of 360 degrees and 180 degrees data acquisition for left ventricular (LV) systolic function in a clinical study and measures LV volume by GBPS compared with ultrasound echocardiography. METHODS AND RESULTS: The study population comprised 9 normal volunteers and 34 patients. GBPS data were acquired by use of 360 degrees rotation and 60 stops per head. All 60 (360 degrees ) and 30 (45 degrees right anterior oblique to 45 degrees left posterior oblique) pieces of projection data that were selected for reconstructing the 180 degrees data were reconstructed and both ventricular functional parameters were automatically obtained by QBS software. The contour of the LV septal wall was concave in 6 patients (14%) when processed at 180 degrees , whereas a concave septum at 360 degrees processing was observed in only 1 patient (2%). The coefficients of correlation between 180 degrees and 360 degrees were 0.467 for the end-diastolic volume (EDV) and 0.648 for the end-systolic volume (ESV). The mean 180 degrees EDV value (152.9 +/- 46.1 mL) was significantly smaller than that of the 360 degrees EDV (191 +/- 70.8 mL) ( P < .001). However, there was no significant difference between the 360 degrees EDV (0.623) and 180 degrees EDV (0.407) as compared by echocardiography ( P = .218). The agreement of the EF between both methods was close ( r = 0.894, P < .0001). The agreement of the right ventricular volumes between the 180 degrees and 360 degrees orbits was close ( r = 0.800 for EDV and 0.706 for ESV). The EF was relatively dispersed between the 180 degrees and 360 degrees methods ( r = 0.642). CONCLUSION: This study showed that SPECT image acquisition by use of both the 180 degrees method and the 360 degrees method considerably underestimated LV volume quantification. In addition, the LV volume with the 180 degrees method was significantly smaller than that with the 360 degrees method. Thus a 360 degrees acquisition orbit may be suitable for more quantitatively accurate results when blood pool imaging is performed with gated SPECT.

Adult↗
PubMedDate not supplied

Intrahepatic portosystemic venous shunt: occurrence in a child patient without liver cirrhosis.

There are multiple reports of intrahepatic portosystemic venous shunt (PSVS) cases in adult patients. We report the case of a 4-year-old child with PSVS and pulmonary arteriovenous malformation (PAVM). Abdominal sonography and computed tomography (CT) revealed the presence of PSVS. T1-weighted magnetic resonance imaging (MRI) demonstrated multiple intracranial hyperintense lesions, mainly in the globus pallidus, which suggested portosystemic encephalopathy. Tc-99m labeled microsphere study showed diffusely increased uptake in the thyroid and kidneys. The scan suggested the existence of PAVM. Pulmonary angiography was performed in order to evaluate pulmonary hypertension, and pulmonary venous pressure was slightly elevated. Contrast echocardiography suggested the presence of an intrapulmonary arteriovenous malformation with significant right-to-left shunt, as evidenced by rapid filling of the left atrium with dissolved bubbles. In this case, contrast echocardiography was helpful in diagnosing the patient's PAVM. In conclusion, we present the case of PSVS with PAVM in childhood. The incidence of PSVS is low, and data from the literature remain limited. However, further investigation is required to clarify the possible correlation between PSVS and PAVM.

Arteriovenous Fistula↗