Biomedical subjects

I Narabayashi

Publications and source records attributed to I Narabayashi.

At least 37 records · Page 2Linked to original sources

PubMed1998

[Clinical usefulness of scatter and attenuation correction for brain single photon emission computed tomography (SPECT) in pediatrics].

This investigation was undertaken to study clinical usefulness of scatter and attenuation correction (SAC) of brain SPECT in infants to compare the standard reconstruction (STD). The brain SPECT was performed in 31 patients with 19 epilepsy, 5 cerebro-vascular disease, 2 brain tumor, 3 meningitis, 1 hydrocephalus and psychosis (mean age 5.0 +/- 4.9 years old). Many patients was necessary to be injected sedatives for restraining body motion after Technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) was injected at the convulsion or rest. Brain SPECT data were acquired with triple detector gamma camera (GCA-9300 Toshiba Japan). These data were reconstructed by filtered backprojection after the raw data were corrected by triple energy windows method of scatter correction and Chang filtered method of attenuation correction. The same data was reconstructed by filtered backprojection without these corrections. Both SAC and STD SPECT images were analyzed by the visual interpretation. The uptake ratio of cerebral basal nuclei was calculated by the counts of the thalamus or lenticular nuclei divided by the cortex. All images of SAC method were excellent than that of STD method. The thalamic uptake ratio in SAC method was higher than that of STD method (1.22 +/- 0.09 > 0.87 +/- 0.22 p < 0.01). The lenticular nuclear uptake ratio in SAC method was higher than that of STD method (1.26 +/- 0.15 > 1.02 +/- 0.16 p < 0.01). Transmission scan is the most suitable method of absorption correction. But the transmission scan is not adequate for examination of children, because this scan needs a lot of time and the infants are exposed by the line source radioisotope. It was concluded that these scatter and absorption corrections were most suitable method for brain SPECT in pediatrics.

Adolescent↗

PubMed1998

[Evaluation of clinical utility of 99mTc-MIBI scintigraphy in the localization of thyroid, breast and lung/mediastinum tumors--a report of multicenter phase III clinical trials].

Phase III clinical study in 136 patients diagnosed or strongly suspected of thyroid, lung/mediastinum or breast cancer was performed to determine clinical utility of 99mTc-MIBI in the localization of tumors, and the results in 135 were evaluated. Except taste peculiar in 43 patients and nausea in one, no adverse events were reported. Seven abnormal changes in vital signs and 27 in clinical laboratories were noted, which were all judged as having no or unlikely relationship to the agent. Out of 177 malignant lesions, 156 (88%) were detected with 99mTc-MIBI regardless of their histology or location. Of 6 benign tumors, 3 were detected. Fifteen sites of false positive in 11 malignant tumor patients and 5 sites in 6 patients with non-tumor disease were observed. Our study indicates that 99mTc-MIBI is a safe and excellent agent for the localization of tumors. Especially, the fact that 99mTc-MIBI detected remote metastatic lesions with high sensitivity is a great advantage over the other conventional imaging modalities.

Adult↗

PubMed1997

Clinical significance of thallium-201 and gallium-67 scintigraphy in pulmonary tuberculosis.

One hundred and thirty-nine patients with pulmonary tuberculosis were evaluated by means of gallium-67 and thallium-201 scintigraphy. The disease was clinically active in 83 and inactive in 56. The uptake ratio between the lesion and the contralateral normal lung field was calculated. The ratio determined by 67Ga scintigraphy was expressed as GR, and that determined by 201T1 scintigraphy (early or delayed) as ER or DR. The 201T1 retention index (RI) was calculated using the following equation: RI = DR - ER/ER x 100. The sensitivity, specificity and accuracy of 201T1 scintigraphy with respect to the activity of pulmonary tuberculosis were better than those of 67Ga scintigraphy (the figures for 201T1 scintigraphy were 88.0%, 82.1% and 85.6%, respectively, and those for 67Ga scintigraphy, 83.1%, 60.7% and 74.1%). We found a significant correlation between GR and ER, but there was no significant correlation between RI and ER. When the relationships between ER, C-reactive protein and 1-h erythrocyte sedimentation rate were examined among patients with abnormal uptake, no significant relationships were noted. In the 27 patients who could be followed up, GR and ER decreased with duration of the therapy, indicating a decrease in disease activity which was consistent with clinical findings. The RI was significantly higher in the early stages of therapy than in the later stages (P < 0.01), suggesting a temporary delay in 201T1 washout in the early stages. The washout seemed to be promoted by the effects of the therapy. Overall, it is concluded that 201T1 scintigraphy is more useful and more suitable than 67Ga scintigraphy for the evaluation of disease activity and therapeutic effects in patients with pulmonary tuberculosis.

Blood Sedimentation↗

PubMed1997

Evaluation of uptake and release of technetium-99m MIBI SPECT of pulmonary and mediastinal lesions.

We evaluated the uptake and release of Tc-99m MIBI in 7 benign and 30 malignant pulmonary and mediastinal lesions. Of the 37 patients, 13 underwent surgery; malignant involvement was examined in 21 mediastinal lymph nodes. Tl-201 SPECT was also performed in 10 patients. Tc-99m MIBI SPECT studies were performed on transverse SPECT images acquired 30 minutes and 3 hours after intravenous injection of 600 MBq of Tc-99m MIBI with three gamma camera detectors (GCA-9300A). Regions of interest were set in the area of abnormal uptake of Tc-99m MIBI and in an area of normal tissue in the contralateral lung. The uptake ratio of the lesion in the contralateral normal lung was obtained on the early image (early ratio; ER) as well as the delayed image (delayed ratio; DR). The benign lesions showed significantly lower ER (1.6 +/- 0.3) and DR (1.4 +/- 0.4) than the malignant lesions (1.9 +/- 0.5 and 1.8 +/- 0.5, respectively; both p < 0.05). There was no significant difference in the retention index (RI), calculated as RI = (DR-ER)/ER x 100. The DR obtained with Tl-201 SPECT images was significantly higher than that obtained with Tc-99m MIBI SPECT (p < 0.05). For the detection of mediastinal lymph node metastases, the early images showed sensitivity, specificity, and accuracy of 85.7%, 100%, and 95.2%, respectively, for the delayed images these values were 85.7%, 92.9%, and 90.5%, respectively. These results suggest that the uptake ratio of Tc-99m MIBI is a useful index in assessing benign or malignant pulmonary and mediastinal lesions.

Aged↗

PubMed1997

Iodine-123 metaiodobenzylguanidine myocardial scintigraphy for prediction of response to beta-blocker therapy in patients with dilated cardiomyopathy.

This study was performed to evaluate whether iodine-123 metaiodobenzylguanidine (MIBG) myocardial scintigraphy could predict the response to beta-blocker therapy in patients with nonischemic dilated cardiomyopathy (DCM). Beta-Blocker therapy is effective in some patients with DCM. MIBG myocardial scintigraphy has also been suggested to be useful in evaluating the severity of myocardial damage in DCM. However, no data exist on whether MIBG imaging can be used to predict which patients with DCM will respond to beta-blocker therapy. We prospectively evaluated whether MIBG myocardial imaging was useful in predicting responses to beta-blocker therapy in patients with DCM. MIBG imaging was performed in 45 patients with DCM (35 men, 10 women, aged 13 to 68 years) before the start of bisoprolol. The heart to mediastinum (H/M) MIBG uptake ratio was evaluated on initial and delayed images, and the percent washout rate of myocardial MIBG was also obtained from these data. Of the 45 patients, 30 (67%) responded to beta-blocker therapy, whereas 2 were resistant and 13 showed progression of heart failure or died of heart failure. By logistic regression analysis, the H/M uptake ratio on delayed images was seen to be a good predictor of the response to beta-blocker therapy with a threshold of 1.7 (sensitivity = 91%, specificity = 92%, accuracy = 91%, positive and negative predictive value = 97% and 80%, respectively). These results indicate that an H/M ratio > 1.7 on the delayed MIBG myocardial scintigraphic images provides a useful indication of whether patients with DCM will respond to beta-blocker therapy.

3-Iodobenzylguanidine↗

PubMed1997

Do repolarization abnormalities in hypertrophic cardiomyopathy represent impaired fatty acid utilization? An observation with QRST isointegral maps.

To identify the clinical significance of the isointegral body surface map of the QRST interval (QRST map) and the occurrence of repolarization abnormalities in patients with hypertrophic cardiomyopathy (HCM), the QRST map and signal-averaged electrocardiogram were evaluated in 50 patients with HCM, in 33 of whom the results were compared with nuclear images both for radioiodine-labeled fatty acid metabolism and for radiothallium perfusion. The QRST departure map was used to determine two parameters of difference between patient and control recordings: the subnormal area (the number of lead points at which the departure index values were negative and lay more than 2 SDs from the mean of the normal control group) and the subnormal minimum (the absolute value of the minimum in the departure map). Late potentials were detected in 6 (12%) of the 50 patients; they were observed in 3 of the 5 patients with dilated-phase HCM but in only 3 (7%) of the other 45 patients. The subnormal area and minimum values were lower in nonobstructive HCM than in dilated-phase HCM. Of the 33 patients examined by myocardial imaging, 28 (33%) had a filling defect or decreased uptake, as shown on fatty acid metabolic images, and 10 of the 28 also showed abnormal myocardial perfusion images, while the 18 others showed normal perfusion images. These 28 patients showed significantly larger values of the subnormal area and minimum than patients with normal results in both image tests, regardless of whether or not myocardial perfusion imaging abnormalities were present. The localization of filling defects or of decreased uptake presented in fatty acid metabolic images corresponded to the position of the minimum on the QRST departure map. These results suggest that the QRST map is useful for detection of repolarization abnormalities in HCM and that these abnormalities are highly related to impaired fatty acid utilization of the myocardium.

Adolescent↗

PubMed1997

[Balloon-occluded intraarterial infusion therapy for advanced uterine cervical cancer: usefulness of four-lumen double balloon catheter].

We have devised a new catheter with four-lumen and a double balloon (4L-DB), which has made it easy to find feeding arteries and enhanced the local concentration of drugs. At first, two 4L-DB catheters were inserted into the contralateral internal iliac artery, via the bilateral femoral arteries. Then, the distal balloon was set in the superior gluteal artery and the proximal balloon in the internal iliac artery. Between the two inflated balloons, anti-cancer drugs (CDDP 100mg, Therarubicin 20mg, MMC 20mg) were infused to the bilateral uterine arteries during 30 minutes via side holes. The response rate for this therapy was 71%, and 3 cases of complete response (CR) were obtained. No severe side effects were observed. In conclusion, the 4L-DB catheter may be an exceedingly efficient method of local anticancer drug infusion.

Antineoplastic Agents↗

PubMed1997

[Usefulness of 99mTc-tetrofosmin myocardial scintigraphy before and after coronary intervention].

Dipyridamole-loading 99mTc-tetrofosmin myocardial scintigraphy was performed for patients with coronary artery disease who underwent percutaneous transluminal coronary angioplasty (PTCA) in order to examine whether SPECT imaging prior to treatment is useful for the determination of prognosis after coronary intervention. Thirty-six patients including 9 with angina pectoris (AP), 22 with old myocardial infarction (OMI) and 5 OMI with AP were underwent dipyridamole-loading 99mTc-tetrofosmin myocardial SPECT before and after coronary intervention. The length of follow-up was 185 +/- 107 days after PTCA. Improvement of myocardial uptake was observed on myocardial SPECT in all cases with AP. Improvement of the myocardial uptake was observed 50% (4/8) of patients with OMI who had no myocardial viability. It was suggested that the improvement of myocardial uptake after PTCA was due to incomplete fill-in in cases with AP and that the presence of fill-in was important for level of fill-in in patients with AP. The improvement of myocardial uptake in the scar tissue in patients with OMI contributed to the hibernating myocardium. We concluded that correct detection of hibernating myocardium was difficult despite the superior imaging capability of 99mTc-tetrofosmin myocardial SPECT.

Aged↗

PubMed1997

Prediction of wall motion improvement after coronary revascularization in patients with postmyocardial infarction: diagnostic value of dobutamine stress echocardiography and myocardial contrast echocardiography.

The diagnostic value of dobutamine stress echocardiography, myocardial contrast echocardiography and dipyridamole stress thallium-201 single photon emission computed tomography (SPECT) for predicting recovery of wall motion abnormality after revascularization was evaluated in 13 patients with postmyocardial infarction. Seventeen segments showed severe wall motion abnormalities before revascularization. Nine segments which had relatively good Tl uptake on delayed SPECT images despite severely abnormal wall motion were opacified during myocardial contrast echocardiography, and showed improved wall motion after revascularization. In contrast, three segments which had poor Tl uptake and severely abnormal wall motion were not opacified during myocardial contrast echocardiography, and showed no improvement in wall motion during dobutamine stress echocardiography and after revascularization. The following three findings were assumed to be signs of myocardial viability: 1) good Tl uptake on delayed SPECT images; 2) improved wall motion by dobutamine stress echocardiography; and 3) positive opacification of the myocardium by myocardial contrast echocardiography. Myocardial contrast echocardiography had the highest sensitivity (100%) and negative predictive value (100%). Delayed SPECT images had the highest specificity (100%) and positive predictive value (100%). Dobutamine stress echocardiography had a sensitivity of 83.0%, specificity of 80.0%, positive predictive value of 90.9%, and negative predictive value of 66.7%, respectively. Myocardial contrast echocardiography showed the lowest specificity (60.0%). The techniques of dobutamine stress echocardiography and SPECT, though noninvasive, may underestimate wall motion improvement after revascularization. Further examination by myocardial contrast echocardiography is recommended to assess myocardial viability for determining the indications for coronary revascularization in spite of its invasiveness.

Cardiotonic Agents↗

PubMed1996

[The usefulness of three-dimensional helical CT for the detection of abnormalities of the auditory ossicles].

To evaluate the usefulness of three-dimensional (3D) helical CT for the detection of abnormalities of the auditory ossicles, 3D helical CT of the middle ear was performed in seven patients with hearing disorder. It revealed that 4 patients had congenital deficiency of the auditory ossicles, 2 patients with chronic otitis media had shortening of the incus and one patient with head injury had doubtful fracture of the incus. This study indicated that 3D helical CT of the middle ear can represent the auditory ossicles objectively and can offer detailed diagnosis.

Adolescent↗

PubMed1996

[Three-phase dynamic helical CT for hepatocellular carcinoma: optimal scanning protocol].

To assess the optimal scanning protocol for three-phase dynamic helical CT, 20 patients were examined according to the following 4 methods (5 cases each) : (1) 100 ml Iopamidol (300 mgI/ml), at a rate of 2 ml/sec ; (2) 120 ml,3 ml/sec, (3) 150 ml, 3 ml/sec ; (4) biphasic method, initial 100 ml, 3.3 ml/sec ; remaining 50 ml, 1.6 ml/sec. Assessment of the time-density curve of the aorta, and the liver parenchyma, indicated that protocol (4) was superior to the others. Using protocol (4), 32 patients (62 nodules) with hepatocellular carcinoma underwent three-phase scanning, consisting of early, late, and delayed phases. Out of 61 nodules, 43 nodules were detected as high density areas in the early phase, 7 nodules as low density areas only in the late phase, and 3 nodules as low density areas only in the delayed phase. Compared with MRI, three-phase dynamic helical CT demonstrated numerous nodules, especially those less than 10 mm in diameter, and, therefore, was useful for the detection of hepatocellular carcinoma.

Aged↗

PubMed1996

[Evaluation of the stability of lipiodol-CDDP: suspension (LCS) by the pumping method].

We purified cisplatin (CDDP) powder from CDDP solution and prepared a Lipiodol-CDDP-suspension (LCS) using the oily contrast medium Lipiodol in order to investigate its stability. Non-ionic contrast materials have surface activity. Iopamidol was chosen as a coupling agent. The compounding ratios of Lipiodol/Iopamidol 300/CDDP for stable suspension were 1 ml/1 ml/10 mg and 1 ml/1 ml/20 mg. These were also obtained easily by using the pumping method.

Antineoplastic Agents↗

PubMed1996

[Three-dimensional CT angiography of the portal vein using multiple threshold display].

To evaluate the usefulness of three-dimensional (3D) CT angiography of the portal vein obtained by using a multiple threshold display, 3D reconstructions were performed in 15 patients. The CT scanner employed was the Toshiba Xvigor. A volume of 150 ml of lopamidol 300 mg1/ml was administered at 3.3 ml/sec intravenously. Portal venous phase helical scanning was initiated 80 seconds after the start of the injection. Helical CT data were acquired using up to 25 continuous 1.0-sec rotations during a single breath-hold with an X-ray beam width of 7 mm and a couchtop movement speed of 7 mm/sec. Axial images were reconstructed at a section interval of 3 mm. Both the shaded surface display (SSD) and multiple threshold display (MTD) were generated by using Xtension with Sparc20. MTD was performed as follows. First, voxels, with higher CT values than that of liver parenchyma, were selected. Then, selected voxels were divided into eight parts, which were each assigned gradations of white to grey. The highest part of selected voxels, with higher CT values than that of the second branch of the portal vein, were set to white and a transparency of 0%. The other seven parts were each assigned transparencies of more than 0%. MTD images were compared with SSD in 15 cases by two radiologists. MTD images were superior to SSD images in quality, because MTD diminished surrounding artifacts due to liver parenchyma and enabled small vessels to be depicted clearly. Based on the above results, it was considered that MTD was a useful method for 3D CT angiography using enhanced helical CT.

Fatty Liver↗

PubMed1995

Evaluation of Tl-201 SPECT for monitoring the treatment of pulmonary and mediastinal tumors.

Tl-201 single photon emission computed tomography (SPECT) was performed in 88 patients with pulmonary or mediastinal tumors in order to evaluate its usefulness for the detection of disease and for the assessment of the effect of treatment. We also examined mediastinal and hilar lymph node metastasis from lung cancer. Tl-201 SPECT showed abnormal accumulation on delayed images in all lung cancer patients with tumor diameters more than 12 mm. In the 14 operated lung cancer patients, mediastinal and hilar lymph node metastases with diameters of more than 15 mm were imaged, but one with a diameter of 9 mm was missed. The retention index (RI) was 27.52 +/- 31.58 in malignant tumors and -13.67 +/- 8.15 in benign tumors (p < 0.05). The RI was significantly lower after treatment than before treatment. The interval until tumor recurrence or reactivation tended to be longer in patients who showed a significant decrease in the RI after therapy. These findings suggest the usefulness of the RI as an index of therapeutic efficacy.

Adenocarcinoma↗

PubMed1995

Tc-99m sestamibi uptake by malignant lymphoma and slow washout.

Tc-99m sestamibi has been used to detect primary brain tumors, lung tumors, and breast cancers. The authors report a patient who had superior vena cava (SVC) syndrome and underwent Tc-99m sestamibi and Tl-201 SPECT to differentiate the tumor from thrombus in the mediastinum because of an abnormal mass lesion on a contrast enhanced CT scan. An abnormal area of increased Tc-99m sestamibi uptake in the supra azygos area was demonstrated on early and delayed SPECT imaging. The washout of tumor uptake was slow. The removed tumor was confirmed to be malignant lymphoma.

Aged↗

PubMed1995

Blueberry juice: preliminary evaluation as an oral contrast agent in gastrointestinal MR imaging.

PURPOSE: To evaluate the use of blueberry juice as an oral contrast agent in magnetic resonance (MR) imaging. MATERIALS AND METHODS: MR imaging of phantoms of blueberry juice and of manganese chloride solutions with different manganese concentrations were conducted. Patient trials were conducted to evaluate manganese blood levels and signal intensity changes on MR images of the abdomen. T1- and T2-weighted conventional spin-echo MR imaging was performed at various field strengths. Six radiologists graded image contrast; signal intensities were calculated. RESULTS: T1 and T2 relaxation curves for blueberry juice and manganese chloride showed similar signal intensity profiles as a function of manganese concentration. Blood concentrations of manganese were unchanged before and after an oral dose of blueberry juice that contained 18 mg of manganese. The results of patient studies indicated that the optimal oral dose of manganese in blueberry juice was 3-4 mg/dL. T1 and T2 shortening were apparent at field strengths of 0.2-1.5 T. CONCLUSION: At appropriate concentrations, blueberry juice has the potential to be an effective oral contrast agent for MR imaging.

Adult↗

PubMed1995

[In vitro uptake and release of 201Tl and 99mTc-MIBI in HeLa cell].

201Tl is useful in the diagnosis of tumor malignancy determined by the grade of washout rate to the normal tissue especially in lung tumors and thyroid tumors. 99mTc-MIBI, a tracer of myocardial blood flow is also a tumor tracer. We determined whether the growth of the tumor cell is related to the uptake and release of the these tracers in cultured cells (HeLa cell). Cultured HeLa cells were incubated for 1 hr with 10 kBq of either tracer for the kinetic study of cellular uptake and additionally incubated for 90 min with cold medium for the kinetic study of cellular release. These cells cultured with various concentrations of actinomycin D (ACD) were used to examine the correlation between cellular growth and kinetics of these tracers. The uptake in the cell reached a plateau at about 60 min and the uptake at 60 min correlated with the number of the cells and was identified for specific accumulation in the cell. The uptake of 201Tl and 99mTc-MIBI at 60 min was 5.17% and 1.32% respectively of the given dose. The release for 90 min showed almost the same tendency for these tracers. The cellular release of 201Tl with the addition of ACD was increased in association with the concentration of ACD. On the other hand, the cellular release of 99mTc-MIBI showed no change by the addition of ACD. In conclusion, 201Tl showed slower washout in high growth cells than in low growth cells, and could act as an indicator of tumor malignancy by assessment of its washout by the tumor.

Culture Media↗

PubMed1995

[Evaluation of AMI-25 enhanced MR imaging and enhanced helical CT for liver tumors].

To evaluate the diagnostic capability of superparamagnetic iron oxide enhanced MRI and enhanced helical CT, 17 patients with histologically or clinically diagnosed hepatocellular carcinoma or metastatic liver tumor and a total of 208 nodules were studied. The pulse sequences used were SE 500/20 (T1WI), SE 2000/20 (PDWI) and SE 2000/70 (T2WI). Contrast medium was administrated intravenously for more than 30 minutes at a dose of 10 mumoles Fe/kg. Enhanced MR images were obtained 30-90 minutes after the injection of contrast medium. With helical CT, 133 nodules were detected. With unenhanced MRI, 62 were detected on T1WI, 60 on PDWI and 77 on T2WI. On the other hand, with enhanced MRI, 165 were detected on T1WI, 190 on PDWI and 186 on T2WI. Enhanced MRI revealed the most nodules among these images (P < 0.05), and was especially effective in detecting small nodules less than 10 mm in diameter (P < 0.05). In conclusion, it was considered that superparamagnetic iron oxide enhanced MRI was useful for the detection of hepatic nodules and that the most adequate pulse sequence was PDWI.

Aged↗