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Biomedical subjects

Junichi Taki

Publications and source records attributed to Junichi Taki.

13 recordsLinked to original sources
PubMed2003

Hemodynamic changes and prognosis in patients with hypertrophic cardiomyopathy and abnormal blood pressure responses during exercise.

BACKGROUND: An abnormal blood pressure response (BPR) during exercise has been proposed as a risk factor for sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). Some patients with HCM show systolic dysfunction during exercise. HYPOTHESIS: The aim of this study was to clarify the hemodynamic response during exercise and prognosis in patients with HCM and abnormal BPR. METHODS: Sixty-five patients with HCM underwent radionuclide monitoring of left ventricular function and measurement of blood pressure during supine ergometer exercise. Thereafter, cardiac events were recorded for an average period of 76 months. RESULTS: Seven of 65 patients had abnormal BPR, while the others had normal BPR. Changes of heart rate and systemic vascular resistance during exercise did not differ between the two groups. Stroke volume did not increase in the abnormal BPR group but did in the normal BPR group. During a mean follow-up period of 76 months, three of the seven patients (43%) with abnormal but only one patient (2%) with normal BPR suffered a malignant arrhythmia. CONCLUSIONS: Abnormal BPR occurred in about 11% of patients with nonobstructive HCM and was associated with a high prevalence of cardiac events. The predictor of abnormal BPR during exercise may not be an abnormal response of systemic vascular resistance and heart rate, but the lack of an appropriate increase in stroke volume.

Blood Pressure↗
PubMed2003

Myocardial viability assessment using nuclear imaging.

Myocardial assessment continues to be an issue in patients with coronary artery disease and left ventricular dysfunction. Nuclear imaging has long played an important role in this field. In particular, PET imaging using 18F-fluorodeoxyglucose is regarded as the metabolic gold standard of tissue viability, which has been supported by a wide clinical experience. Viability assessment using SPECT techniques has gained more wide-spread clinical acceptance than PET, because it is more widely available at lower cost. Moreover, technical advances in SPECT technology such as gated-SPECT further improve the diagnostic accuracy of the test. However, other imaging techniques such as dobutamine echocardiography have recently emerged as competitors to nuclear imaging. It is also important to note that they sometimes may work in a complementary fashion to nuclear imaging, indicating that an appropriate use of these techniques may significantly improve their overall accuracy. In keeping these circumstances in mind, further efforts are necessary to further improve the diagnostic performance of nuclear imaging as a reliable viability test.

Cell Survival↗
PubMed2003

Predicting the outcome of distraction osteogenesis by 3-phase bone scintigraphy.

UNLABELLED: Distraction osteogenesis is an effective method for lengthening long bones and filling bone defects that result from bone resection. Insufficiency of bone consolidation in the distraction segment is problematic. In this study, we examined whether 3-phase bone scintigraphy can predict the outcome of distraction osteogenesis. We also investigated the effects of chemotherapy and surgical treatment on distraction osteogenesis. METHODS: We performed 3-phase bone scintigraphy on 60 patients (9 high-grade malignant bone tumors as group A, 11 low-grade malignant or benign tumors as group B, 40 nontumoral conditions as group C) with distraction osteogenesis at the lengthening phase of the long bones. By setting the region of interest on the distraction segment and contralateral normal area, we calculated the perfusion index (PI), the uptake ratio of the blood-pool image (BPR), and the uptake ratio of the delayed image (DR). Patients were classified into poor and good consolidation groups from the radiographic findings of the distraction segment. RESULTS: Good to fair correlations were obtained between the PI and BPR, the PI and DR, and the BPR and DR (r = 0.65, 0.45, and 0.57, respectively). The PI and BPR indicated no significant differences among group A-C (1.7 +/- 0.6, 2.1 +/- 0.7, and 1.8 +/- 0.8 in PI, respectively; 1.8 +/- 1.1, 1.9 +/- 0.5, and 2.0 +/- 0.7, in BPR, respectively). The DR of group A (2.4 +/- 1.2) was significantly lower than that of group B (6.3 +/- 1.8; P = 0.001) and group C (5.9 +/- 2.8; P < 0.001). Eleven patients were classified in the poor consolidation group. The other 49 patients showed good consolidation. The poor consolidation group showed lower values in all indices obtained by 3-phase bone scintigraphy than the good consolidation group. The optimal cutoff levels, sensitivity, specificity, and accuracy of each index for detection of patients with poor consolidation were as follows: 1.1, 36%, 90%, and 80% in the PI, respectively; 1.2, 55%, 94%, and 87% in the BPR, respectively; and 2.2, 82%, 96%, and 93% in the DR, respectively. CONCLUSION: Three-phase bone scintigraphy is a promising method for the assessment of distraction osteogenesis. The delayed image of 3-phase bone scintigraphy, especially, is an excellent modality for predicting the outcome of distraction osteogenesis.

Adolescent↗
PubMed2002

Myocardial distribution of (18)F-FDG and (99m)Tc-sestamibi on dual-isotope simultaneous acquisition SPET compared with PET.

A dual-isotope simultaneous acquisition (DISA) single-photon emission tomography (SPET) protocol with fluorine-18 fluorodeoxyglucose ((18)F-FDG) and a technetium-99m labelled flow tracer is attractive because it permits assessment of both myocardial glucose utilisation and flow within a single study. Differences in physical and physiological characteristics between (18)F-FDG and the (99m)Tc-labelled flow tracer, however, may cause differences in myocardial activity distribution between the agents. The aim of this study was to investigate the relation between the myocardial distribution of (18)F-FDG and a (99m)Tc-labelled flow tracer on DISA SPET in comparison with nitrogen-13 ammonia/(18)F-FDG positron emission tomography (PET). Nine normal volunteers without cardiac disease and ten patients with known coronary artery disease (CAD) underwent (13)N-ammonia/(18)F-FDG PET and (99m)Tc-sestamibi/(18)F-FDG DISA SPET. Using a semiquantitative polar map approach, the left ventricular myocardium was divided into nine segments, and relative regional activity was calculated for each segment. A segment was considered to have concordant uptake between (18)F-FDG and flow tracer if the difference in measured regional activity between the tracers was < or =10% of peak activity, and the percentage of concordant segments was calculated for each subject. There was a good overall concordance of myocardial activity between the agents on DISA SPET (84.0%+/-14.8%) in normals, which was comparable to that seen on PET (86.4%+/-14.5%, NS vs DISA SPET). However, the myocardial activity distributions of (18)F-FDG and flow tracer were not identical in that reduced flow tracer activity was seen in the basal segments on DISA SPET in both normals and CAD patients. It is concluded that there is good overall concordance of activity between (18)F-FDG and flow tracer in normal myocardium on DISA SPET, which is comparable to that on PET, supporting the use of combined (99m)Tc-flow tracer/(18)F-FDG imaging for the detection of viable myocardium. However, there is a difference in the myocardial activity distribution between the agents in both normals and CAD patients, the difference being particularly evident in the basal segments. Therefore, careful image interpretation that takes into consideration the different normal activity distribution between the tracers and/or a tracer-specific normal database is necessary for comparison with patient studies.

Adult↗
PubMed2002

Spontaneous development of left ventricular aneurysm in a patient with untreated cardiac sarcoidosis.

A young adult patient with untreated sarcoidosis spontaneously developed a left ventricular (LV) aneurysm in the anterolateral free wall. Single-photon emission computed tomography (SPECT) using Gallium-67 clearly demonstrated widespread abnormal uptake, including the LV aneurysm. Thallium-201 SPECT revealed a perfusion defect in the anterolateral wall, and abnormal uptake of technetium-99m pyrophosphate was seen, especially in the borders of the defect lesion.

Adult↗
PubMed2002

Heterogeneity of cardiac sympathetic nerve activity and systolic dysfunction in patients with hypertrophic cardiomyopathy.

UNLABELLED: Cardiac sympathetic nerve activity is changed in patients with hypertrophic cardiomyopathy (HCM). However, the relationship between heterogeneity of this activity and systolic left ventricular dysfunction in patients with HCM is not well established. This study was performed to evaluate the sympathetic nerve activity in various cardiac regions and to investigate the relationship between cardiac dysfunction and heterogeneity of the cardiac sympathetic nerve activity in patients with HCM. METHODS: Cardiac sympathetic nerve activity was evaluated in 25 patients with HCM and 10 control subjects using planar imaging and SPECT by 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy. With planar 123I-MIBG imaging, the heart-to-mediastinum activity ratios (H/M), at early (20 min) and delayed (3 h) acquisition, and the washout rate were calculated. Polar maps of the left ventricular myocardium were divided into 20 segments, and the dispersion (maximal to minimal values) and SD of uptake and the washout rate in 20 segments were calculated. RESULTS: The early H/M did not differ between the 2 groups. The delayed H/M was significantly lower and the washout rate of the whole heart was significantly higher in the HCM group than those in the control group. In patients with HCM, the delayed H/M, early uptake dispersion, and SD of early uptake showed good correlation with the left ventricular end-diastolic and end-systolic dimensions and the percentage of fractional shortening. A stepwise regression analysis revealed that the SD of early uptake was a powerful determinant for the percentage of fractional shortening in patients with HCM. CONCLUSION: These results suggest that the heterogeneity of regional cardiac sympathetic nerve activity may be correlated with cardiac dysfunction in patients with HCM.

3-Iodobenzylguanidine↗
PubMed2002

Electrocardiographic gated (99m)Tc-MIBI SPECT for functional assessment of patients after coronary artery bypass surgery: comparison of wall thickening and wall motion analysis.

UNLABELLED: Abnormal septal motion after coronary artery bypass graft surgery (CABG) is a common finding. This study was undertaken to investigate the change in various global and regional ventricular function parameters measured by gated myocardial perfusion SPECT after surgery and to determine which quantitative parameter of WT and WM is more appropriate for the evaluation of regional cardiac function, especially in the septum of patients with CABG. METHODS: Before and 3 to 5 wk after CABG (all patients underwent at least 1 bypass grafting to the left anterior descending coronary artery), 35 patients (28 men, 7 women) underwent gated SPECT using (99m)Tc-methoxyisobutylisonitrile. Quantitative global and regional ventricular functional analysis was performed using quantitative gated SPECT software. RESULTS: Global ejection fraction did not change (59.3% +/- 16.0% to 60.5% +/- 14.5%, P = 0.24). However, end-diastolic and end-systolic volumes lessened significantly after CABG (81.4 +/- 37.3 mL to 68.9 +/- 28.9 mL, P < 0.0001, and 38.1 +/- 33.1 mL to 30.4 +/- 23.0 mL, P < 0.005, respectively). As global function parameters, the changes in both total WM (r = 0.88) and WT (r = 0.86) correlated well with the change in ejection fraction after surgery. Segmental analysis showed a significant postoperative increase in relative tracer uptake in the anterior, anteroseptal, inferoseptal, and inferior walls and in the apex. Segmental wall motion (WM) deteriorated in the anteroseptal, inferoseptal, and mid anterior walls. On the other hand, anterolateral, inferolateral, and inferior WM increased. As a whole, these WM changes showed a reduction in septal motion associated with a concomitant increase in lateral motion after surgery. Segmental wall thickening, however, did not decrease in septal areas and did not increase in the lateral wall and correlated with percentage tracer uptake (r = 0.69) better than WM did (r = 0.30) after CABG. CONCLUSION: In patients with CABG, postoperative WM analysis by gated SPECT underestimated septal motion and overestimated lateral motion because of exaggerated systolic anteromedial cardiac translation. Therefore, wall thickening analysis would be recommended for the evaluation of postoperative cardiac function.

Aged↗
PubMed2002

Prediction of myocutaneous adverse side effect due to intra-arterial chemotherapy by intra-arterial (99m)Tc-macroaggregated albumin administration in patients with bone and soft-tissue tumors.

UNLABELLED: In malignant bone and soft-tissue tumors, intra-arterial chemotherapy and limb-saving surgery have become popular. Myocutaneous inflammatory change and necrosis are the major local side effects of intra-arterial chemotherapy. (99m)Tc-macroaggregated albumin (MAA) imaging with intra-arterial tracer administration was performed to evaluate drug distribution, and the ability of (99m)Tc-MAA imaging to predict local side effects was assessed. METHODS: In 24 patients, 42 (99m)Tc-MAA images were obtained with tracer injection through an intra-arterial catheter that was inserted into the proximal portion of the tumor-feeding artery. Abnormal uptake other than by tumor was assessed visually and quantitatively. RESULTS: In visual analysis, abnormal (99m)Tc-MAA accumulation was observed in 21 of 42 images. In the first consecutive 13 of these 21 images, intra-arterial chemotherapy with cisplatin, doxorubicin, and caffeine was administered, and myocutaneous inflammation or necrosis in the area corresponding to the abnormal (99m)Tc-MAA uptake was observed in 11. In contrast, none of the 21 images without abnormal (99m)Tc-MAA uptake demonstrated any local adverse effect from intra-arterial chemotherapy. In the last consecutive 8 images with abnormal (99m)Tc-MAA uptake, intra-arterial chemotherapy was initiated with only cisplatin, and doxorubicin and caffeine administration was changed to the intravenous route. In all 8 of these images, no local adverse effects from chemotherapy were observed. Overall, the sensitivity, specificity, and accuracy of (99m)Tc-MAA imaging for the detection of myocutaneous damage were 100% (11/11), 91% (21/23), and 94% (32/34), respectively, and positive and negative predictive values were 85% (11/13) and 100% (21/21), respectively. In quantitative analysis, when the diagnostic threshold of the uptake ratio was set at 2.5, sensitivity, specificity, and accuracy for the detection of myocutaneous complications were 91% (10/11), 96% (22/23), and 94% (32/34), respectively, and positive and negative predictive values were 91% (10/11) and 96% (22/23), respectively. CONCLUSION: (99m)Tc-MAA imaging with intra-arterial infusion before intra-arterial chemotherapy for bone and soft-tissue tumors can facilitate prediction of local myocutaneous adverse effects due to chemotherapy.

Adolescent↗
PubMedDate not supplied

Cardiac sympathetic nerve activity in patients with hypertrophic cardiomyopathy with malignant ventricular tachyarrhythmias.

BACKGROUND: Malignant ventricular tachyarrhythmia (VT) and sudden death are serious events in hypertrophic cardiomyopathy (HCM). However, the pathophysiology of this condition is not well understood. The objective of this study was to evaluate the relationship between cardiac sympathetic nerve activity and the occurrence of VT in HCM patients. Methods and results We studied iodine 123 metaiodobenzylguanidine scintigraphy and 24-hour ambulatory electrocardiographic monitoring in 44 HCM patients, 15 with VT (group A) and 29 without VT (group B). With planar I-123 metaiodobenzylguanidine imaging, the heart-to-mediastinum ratio for early and delayed acquisition and washout rate were calculated. Polar maps of left ventricular myocardium were divided into 20 segments, and the SD of uptake and washout rate in 20 segments were calculated as indices of regional variation. The global washout rate was significantly higher in group A than in group B (26.8 +/- 6.4% vs 17.4 +/- 5.7%, P <.0001), although other parameters including heterogeneity indices did not differ. The logistic multiple regression analysis also determined that washout rate was the most powerful predictor of VT in patients with HCM. CONCLUSIONS: The occurrence of malignant VT in HCM may be associated with global cardiac sympathetic nerve activity rather than with the heterogeneity of this activity.

3-Iodobenzylguanidine↗