PubMed Health⌕ Search

Biomedical subjects

E Tadamura

Publications and source records attributed to E Tadamura.

51 records · Page 3Linked to original sources
PubMed1995

Decreased uptake of iodinated branched fatty acid analog indicates metabolic alterations in ischemic myocardium.

UNLABELLED: We previously reported that uptake of 123I-labeled 15-iodophenyl 3-methyl pentadecanoic acid (BMIPP) was lower than that of thallium in ischemic myocardium. Such discordant findings between BMIPP and thallium were compared with those of PET using 18F-deoxyglucose (FDG) and 11C-acetate to assess metabolic alterations in such segment. METHODS: Sixteen patients with coronary artery disease underwent both BMIPP SPECT and PET. Relative FDG uptake (% FDG uptake) and the clearance rate constant (% Kmono) of 11C-acetate from the myocardium were calculated as markers of glucose and oxidative metabolism, respectively. RESULTS: Relative FDG uptake of the myocardial segments with reduced BMIPP uptake and normal thallium uptake (discordant segments) was similar (85.3 +/- 10.3) to that of the normal segments (86.5 +/- 11.7) but higher than that of segments with reduced uptake of both BMIPP and thallium (67.5 +/- 19.9). Similarly, the discordant segments showed a higher % Kmono value (77.8 +/- 13.1 versus 70.0 +/- 19.1) and FDG-to-perfusion ratio (1.15 +/- 0.08 versus 1.01 +/- 0.22) than in the concordantly reduced segments. CONCLUSION: BMIPP uptake appears to provide metabolic information independent of thallium uptake. Combined imaging of BMIPP and thallium may potentially identify ischemic but viable myocardium.

Acetates↗
PubMed1995

Myocardial oxidative metabolism in hyperthyroid patients assessed by PET with carbon-11-acetate.

UNLABELLED: Hyperthyroid patients often complain of cardiovascular symptoms because of increased metabolism. This study was designed to quantitatively evaluate myocardial oxidative metabolism in these patients. METHODS: Dynamic PET with 11C-acetate was performed in 19 patients who had not undergone treatment for hyperthyroidism. Eight were restudied 2 wk after oral administration of propranolol. The clearance rate constant of 11C-acetate (Kmono) was calculated with monoexponential fitting of tracer washout from the myocardium as a marker of myocardial oxidative metabolism. The results were compared with those in nine normal subjects both at rest and during dobutamine infusion. RESULTS: Kmono in our patients (0.109 +/- 0.028 min-1) was significantly increased compared to normal subjects (0.066 +/- 0.016 min-1) (p < 0.05). After propranolol treatment, Kmono decreased (0.082 +/- 0.014 min-1) but remained significantly higher in eight patients than normal subject levels (p < 0.05), while the rate pressure product decreased significantly (7500 +/- 1700) toward the normal range (7900 +/- 1500). CONCLUSION: These results suggest the possibility of excessive myocardial oxygen consumption in hyperthyroid patients. The clearance rate of 11C-acetate is a new and valuable index to assess myocardial oxidative metabolism not closely related to the pressure rate product or thyroid hormones in these patients.

Acetates↗
PubMed1995

[Myocardial uptake ratio of iodine-123 labeled beta-methyl iodophenylpentadecanoic acid (123I-BMIPP) in relation to the concentration of the substrates of energy].

Iodine-123 beta-methyl iodophenylpentadecanoic acid (BMIPP) has been used for evaluating myocardial fatty acid metabolism in vivo. The whole body BMIPP imaging was acquired in 26 patients (11 with HCM, 11 with CAD and 4 with DCM) to calculate % uptake in the myocardium and to correlate its uptake with biochemical data, including blood sugar (BS), nonesterified fatty acid (NEFA) and insulin in the blood. BMIPP was administered at rest with overnight fasting state, and the anterior and posterior whole body imaging was performed one hour later. The background corrected whole myocardial counts were calculated to obtain %BMIPP uptake. In addition, the heart to mediastinum count ratio (H/M ratio) was calculated from the mean counts in the heart and the upper mediastinum in the anterior view. The %BMIPP uptake was 3.70 +/- 1.22% and H/M ratio was 2.30 +/- 0.23. The patients with DCM showed higher %BMIPP uptake values (DCM = 5.58 +/- 0.67% vs. CAD = 3.09 +/- 0.97% and HCM = 3.63 +/- 0.86%, both p < 0.01), but similar values of H/M ratio with other patients (DCM = 2.43 +/- 0.20, CAD = 2.22 +/- 0.25 and HCM = 2.32 +/- 0.20). Although the biochemical data varied at the time of the tracer administration, they were not significantly correlated with the %BMIPP uptake or H/M ratio. However, there was a significant correlation between %BMIPP uptake and H/M ratio with the correlation coefficient of 0.80 (p < 0.001). We conclude that the myocardial uptake of BMIPP is not influenced by the plasma substrate level under the fasting state.

Blood Glucose↗
PubMed1995

[Quantitative analysis of myocardial tracer distribution in patients with ischemic heart disease: comparison of 201T1 and 123I-15-(p-iodophenyl)-3-methylpentadecanoic acid (BMIPP)].

Quantitative assessment of myocardial tracer uptake in stress-delayed thallium and resting BMIPP imagings were performed in 24 patients with coronary artery disease. Each distribution was displayed on the bull's eye polar map and % uptake of each distribution was calculated as a mean value in 9 myocardial segments on the polar map. Redistribution index (% delayed uptake minus % stress uptake on thallium images) and discordance index (% delayed thallium uptake minus % BMIPP uptake) were also calculated. Each parameter was compared to the visual uptake score and wall motion score on contract left ventriculography. Excellent correlations were obtained between % uptake and the uptake score in each tracer. The % thallium and BMIPP uptake also correlated with regional wall motion score. Furthermore, a significant correlation was observed between redistribution and discordance indexes in the mildly hypoperfused segments. These data indicate that the quantitative analysis of thallium and BMIPP distributions seems to be valuable to understand relationship between perfusion and regional wall motion. The discordant BMIPP uptake may represent asynergic but viable segments. However, several important factors, such as attenuation factor should be also taken into consideration for such quantitative analysis.

Aged↗
PubMed1995

Age and gender differences in normal myocardial adrenergic neuronal function evaluated by iodine-123-MIBG imaging.

UNLABELLED: Myocardial sympathetic nervous function has been evaluated with 123I-metaiodobenzylguanidine (MIBG) imaging in various cardiac diseases. Heterogeneous distribution of this tracer has been reported. This study was undertaken to assess whether such heterogeneity is related to age and gender. METHODS: Twenty-nine subjects (18 men, 11 women; age range, 21 to 79 yr; mean age 42 +/- 17 yr) with no cardiac disorders were studied. Early (15 min) and late (3-4 hr) planar images were taken, and SPECT images were also obtained 3-4 hr after MIBG injection (111 MBq). The mean counts of the whole heart, mediastinum and the anterior and inferior regions of the heart were obtained to calculate heart-to-mediastinum count ratios, myocardial washout rates and the inferior-to-anterior wall count ratio. On a bull's-eye map of the SPECT images, the left ventricular myocardium was divided into nine sectors to calculate the inferior-to-anterior wall count ratio. RESULTS: There were no significant differences in the heart-to-mediastinum count ratio based on age or gender, but there was a significant inverse correlation between the inferior-to-anterior wall count ratio and age (r = -0.51 on late planar images and r = -0.69 on SPECT; p < 0.01 and p < 0.001, respectively). This correlation was valid in men (r = -0.74 and -0.83, respectively; both p < 0.001), but not in women (r = -0.25 and -0.34, respectively; p = ns). CONCLUSION: Inferior wall uptake of MIBG decreased with age in individuals without cardiac diseases, especially men. Such age- and gender-related heterogeneity should be considered in the interpretation of MIBG images.

3-Iodobenzylguanidine↗
PubMed1994

Combined study with I-123 fatty acid and thallium-201 to assess ischemic myocardium: comparison with thallium redistribution and glucose metabolism.

To assess the clinical value of combined SPECT imaging with I-123-15-(p-iodophenyl)-3-methyl pentadecanoic acid (BMIPP) and thallium-201 (Tl), the findings were compared with those obtained in a stress Tl study and positron emission tomography (PET) with fluorine-18-fluorodeoxyglucose (FDG) in 22 patients with myocardial infarction. In 20 patients who underwent a stress Tl study, among 75 hypoperfused segments, 27 segments exhibited less BMIPP uptake than Tl (discordant segments), and the remaining 48 segments showed a similar decrease in BMIPP uptake (concordant segments). Twenty-two of 27 discordant segments (81%) exhibited redistribution on stress Tl study. On the other hand, only one of the 48 concordant segments had redistribution (p < 0.001). In 10 patients who underwent a FDG PET study, among 33 hypoperfused segments, seven segments were discordant segments, and the remaining 25 segments were concordant segments. Seven of the eight discordant segments (88%) demonstrated an increase in FDG uptake. In contrast, only five of 25 concordant segments (20%) showed increase in FDG uptake (p < 0.01). Thus, the segments showing discordant BMIPP uptake are considered to be ischemic but viable myocardium. We conclude that combined imaging with BMIPP and Tl is a useful mean for evaluating tissue viability in patients with coronary artery disease, but it may underestimate the extent of tissue viability, compared with FDG PET imaging.

Adult↗
PubMed1994

Myocardial tomography using technetium-99m-tetrofosmin to evaluate coronary artery disease.

UNLABELLED: To assess the clinical value of the 99mTc-labeled myocardial perfusion agent, 99mTc-tetrofosmin, the findings of stress and rest myocardial tomography were compared with those of stress and 3-hr delayed 201Tl tomography and coronary arteriography. METHODS: Twenty-five patients who had coronary arteriography were studied with both stress tetrofosmin and 201Tl tomography. RESULTS: The image quality of tetrofosmin was superior to that of 201Tl despite a shorter acquisition time. Both the tetrofosmin and 201Tl studies were quite sensitive to detect coronary artery disease (100% and 95%, respectively) (p = ns). The two studies showed similar sensitivity (75% and 73%) and specificity (80% and 77%, respectively) for the detection of significant (> or = 75% diameter) coronary artery stenosis. Stress distribution of tetrofosmin tended to be slightly higher than that of 201Tl (% uptake: 63.3% +/- 13.5% versus 60.4% +/- 12.2%, p = 0.0006; uptake score: 2.33 +/- 1.03 versus 2.22 +/- 1.07, p = 0.007), indicating less defect contrast in the former. A high concordant rate (89%) of the stress perfusion score was observed between the two radiopharmaceuticals. Reversible perfusion abnormalities were observed to be similar between stress-rest tetrofosmin and stress-delayed 201Tl studies. CONCLUSIONS: Stress tetrofosmin perfusion tomography is a valuable method to detect coronary artery disease and to assess tissue viability with accuracy similar to that of stress 201Tl tomography.

Aged↗
PubMed1993

Oxidative metabolism in the myocardium in normal subjects during dobutamine infusion.

To assess the biventricular response of the clearance rate of carbon-11 acetate as an index of myocardial oxidative metabolism to increase in work-load, dynamic positron emission tomography was performed at rest and during dobutamine infusion in 14 normal subjects. The clearance rate constant (Kmono) of the left ventricular (LV) myocardium increased during dobutamine infusion (0.112 +/- 0.020 min-1 vs 0.065 +/- 0.015 min-1 at rest) (P < 0.001) in proportion to the increase in the pressure-rate product. Kmono in the right ventricular (RV) myocardium also increased (0.080 +/- 0.018 min-1 vs 0.034 +/- 0.013 min-1 at rest) (P < 0.001), with an excellent correlation with the LV Kmono (r = 0.920). The fact that the increase in RV Kmono during dobutamine infusion was greater (158% +/- 81%) than that in LV Kmono (79% +/- 39%) (P < 0.005) indicates a greater increase in oxidative metabolism in the RV in response to inotropic stimulation in normal subjects.

Acetates↗
PubMed1992

Myocardial oxidative metabolism in normal subjects in fasting, glucose loading and dobutamine infusion states.

Experimental studies indicated the clearance rate constant of 11C-acetate as an index of regional myocardial oxygen consumption. To assess the response of the clearance rate from the left ventricular (LV) myocardium to the change in plasma substrate levels and to the increase in the cardiac work load in normal subjects, a total of 18 dynamic positron emission tomographic studies were performed at rest in the fasting state (control) (n = 7), after oral glucose administration (n = 4), and during dobutamine infusion (n = 7) in 7 normal volunteers. The clearance rate constant (Kmono) was similar in the control (0.065 +/- 0.017 min-1) and glucose loading states (0.059 +/- 0.008 min-1), whereas a significant increase in Kmono was observed during dobutamine infusion (0.106 +/- 0.018 min-1) (p < 0.01) in relation to the increase in the pressure-rate product with a correlation coefficient of 0.873 (p < 0.01). When the LV myocardium was divided into 6 segments, there were no significant differences among the segments in Kmono values in any condition. These normal responses should be valuable for assessing oxidative metabolic reserve and regional changes in oxidative metabolism in patients with coronary artery disease.

Adult↗
PubMed1991

[Follow-up study in a case of traumatic epilepsy with increased accumulation of 123I-N-isopropyl-p-iodoamphetamine].

Recent studies suggested the potential use of 123I-N-isopropyl-p-iodoamphetamine (IMP) for the assessment of pathophysiology of epilepsy. We studied a case of epilepsy with increased accumulation of IMP. Brain SPECT scan of IMP was performed in a case of 31-year-old male with traumatic epilepsy. Increased accumulation of IMP was observed in the left temporal area on both early (20 min after injection) and delayed (3 hr) images of studied 6 weeks after the head trauma. X-CT did not show any abnormalities. The accumulation of IMP decreased as the symptom of the patient improved. The SPECT study performed 3 months after the accident showed slightly decreased uptake in the left temporal area on the early image with homogeneous uptake in the delayed image. These findings suggested the altered retention mechanism of IMP in this case.

Adult↗
PubMed1990

Episodic fluctuation in serum intact parathyroid hormone concentration in men.

To evaluate the temporal features of physiological fluctuation in serum PTH concentration, we sampled peripheral blood at 4-min intervals for 24 h from five normal men (32.8 yr; range, 26-40 yr) and measured serum PTH levels using a two-site immunoradiometric assay with the exquisite sensitivity and specificity for human PTH-(1-84) (intact PTH). The resultant 24-h time series of serum intact PTH levels were assessed by contemporary techniques in chronophysiology for rhythmic and episodic peak detection. Cosinor analysis disclosed a significant circadian rhythm in serum intact PTH concentrations in all five men, with the mean circadian amplitude and acrophase of 7.2 +/- 4.4 ng/L and 2305 +/- 401 h, respectively (mean +/- SD; n = 5). No apparent fixed ultradian periodicity was found by autocorrelation and spectral analyses. Evaluation of episodic intact PTH pulsatility by Cluster analysis revealed 23.0 +/- 4.4 discrete PTH pulses/24 h (P less than 0.01 vs. signal-free noise), which occurred at an interpulse interval of 61.6 +/- 11.1 min. The average duration of a serum intact PTH peak was 42.8 +/- 7.3 min, and its mean incremental amplitude was 12.6 +/- 1.3 ng/L, which corresponded to a 31.8 +/- 5.2% increase above the preceding nadir. Discrete PTH peaks were separated by nonpulsatile valleys which lasted for 17.9 +/- 4.4 min. Cross-correlation between the time series of serum intact PTH and whole blood ionized calcium (Ca2+) was at its maximum (-0.5) at concurrent time points in three subjects, while significant positive correlation between serum intact PTH and simultaneous serum inorganic phosphorus concentrations was observed in four of five subjects. There was no apparent correlation between the levels of serum intact PTH and serum magnesium. Our data show that serum levels of intact PTH, the only biologically active form of PTH in the blood, is characterized by a significant circadian periodicity, spontaneous episodic pulsatility with distinct peak properties, and a significant temporal coupling with Ca2+ and inorganic phosphorus concentrations. We conclude that PTH secretion, as judged by the temporal pattern of serum intact PTH levels, is pulsatile in normal men.

Adult↗
PubMedDate not supplied

Effect of oxygen inhalation on relaxation times in various tissues.

The effect of the oxygen inhalation on relaxation times was evaluated in various tissues, including the myocardium, liver, spleen, skeletal muscle, subcutaneous fat, bone marrow, and arterial blood, with a [1H]MR system. Statistically significant decrease of T1 relaxation times was observed in the myocardium, spleen, and arterial blood after inhalation of 100% oxygen, whereas no significant change was observed in liver, skeletal muscle, subcutaneous fat, or bone marrow. The T2 relaxation time of these tissues did not differ significantly between before and after inhalation of the oxygen. These results indicate that [1H]MRI can be used to evaluate changes with oxygen inhalation and that the effect of the oxygen inhalation on T1 relaxation time is different among various tissues.

Adipose Tissue↗
PubMedDate not supplied

Significance of myocardial uptake of iodine 123-labeled beta-methyl iodophenyl pentadecanoic acid: comparison with kinetics of carbon 11-labeled palmitate in positron emission tomography.

BACKGROUND: A radioactively labeled beta-methyl branched fatty acid analog, 123I-15-(p-iodophenyl)-3-methyl pentadecanoic acid (BMIPP), has been developed to probe regional myocardial fatty acid metabolism. However, the significance of BMIPP uptake in the myocardium remains unclear. METHODS AND RESULTS: To evaluate the significance of BMIPP uptake, single-photon emission computed tomography was performed 30 minutes after injection of BMIPP, and 201Tl-labeled single-photon emission computed tomography was taken on a separate day in 10 patients. Findings of BMIPP and 201Tl-labeled imaging were compared with the data obtained from positron emission tomography with 11C-labeled palmitate. The BMIPP uptake (percent of maximum) was significantly correlated with the early uptake (percent) and delayed uptake (percent) of 11C-labeled palmitate (r = 0.659 and r = 0.687, respectively) (p < 0.01 each), whereas it was not significantly correlated with the residual fraction (r = 0.205) or the clearance half-time of the early component (r = 0.138) of 11C-labeled palmitate as a marker of beta-oxidation of the fatty acid. CONCLUSIONS: These data indicate that, although the myocardial uptake of BMIPP may not directly reflect beta-oxidation of fatty acids, its uptake may reflect both regional myocardial blood flow and fatty acid extraction.

Adult↗
PubMedDate not supplied

Combined assessment of regional perfusion and wall motion in patients with coronary artery disease with technetium 99m tetrofosmin.

BACKGROUND: Technetium 99m tetrofosmin is a new 99mTc-labeled myocardial perfusion agent that can be labeled easily and provides excellent myocardial perfusion images. In addition, bolus administration of the tracer allows first-pass radionuclide ventriculography. METHODS AND RESULTS: This study examined the diagnostic value of combined assessment of regional perfusion by tetrofosmin tomography and wall motion by first-pass radionuclide ventriculography both at rest and during stress in 24 patients suspected of having coronary artery disease. All patients underwent stress-rest tetrofosmin tomography, stress-delayed thallium 201 tomography, and coronary angiography. Stress tetrofosmin tomography showed abnormal perfusion in all 23 patients with angiographic evidence of coronary artery disease, whereas stress 201Tl tomography showed abnormal perfusion in 22 of the 23 patients. For detection of significant (> or = 50% diameter stenosis) stenotic coronary arteries, the two perfusion studies showed similar sensitivities (62% with 201Tl and 69% with tetrofosmin) and specificities (88% and 100%, respectively). When analysis of regional wall motion was combined with perfusion study, a slightly higher sensitivity was obtained (77%), with similar specificity. The regional wall motion score was concordant with the regional perfusion score in only 42% of the segments at rest and 50% during exercise. CONCLUSIONS: These results suggest that stress tetrofosmin perfusion tomography and stress 201Tl tomography provided similar diagnostic accuracy for detection of coronary artery disease. The combined assessment of perfusion and function that is feasible with tetrofosmin may enhance diagnostic accuracy in patients with coronary artery disease.

Aged↗