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Biomedical subjects

Taishiro Chikamori

Publications and source records attributed to Taishiro Chikamori.

At least 19 recordsLinked to original sources
PubMed2006

The role of 123I-metaiodobenzylguanidine myocardial scintigraphy in the diagnosis of Lewy body disease in patients with dementia in a memory clinic.

Reduction in cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake is a characteristic feature of Parkinson's disease (PD) and dementia with Lewy bodies (DLB), and is useful in distinguishing them from other neurodegenerative disorders. The aim of this study was to investigate the role of this method of scintigraphy in the differential diagnosis of dementia in our Memory Clinic. We performed MIBG scintigraphy in patients with dementia referred to the Memory Clinic and compared the heart-to-mediastinum (H/M) ratio of MIBG uptake. Thirty out of 32 patients with DLB and all 9 PD with dementia patients had reduced H/M ratios, whereas 37 out of 40 patients with Alzheimer's disease had normal H/M ratios. Most patients with vascular dementia, frontotemporal dementia, and other dementias had normal H/M ratios. The overall sensitivity to positively identify patients with Lewy body disease (including DLB and PD with dementia) was 95%, and the specificity to distinguish them from patients with other types of dementias was 87%. MIBG scintigraphy showed a high sensitivity for the detection of Lewy body disease, and also a high specificity for discrimination from other types of dementia. The scintigraphy may provide a valuable and adjunctive method in the diagnosis of Lewy body disease and a differential diagnostic tool for patients with dementias.

3-Iodobenzylguanidine↗
PubMed2006

Alpha B-crystallin mutation in dilated cardiomyopathy.

Mutations in genes for sarcomeric proteins such as titin/connectin are known to cause dilated cardiomyopathy (DCM). However, disease-causing mutations can be identified only in a small proportion of the patients even in the familial cases, suggesting that there remains yet unidentified disease-causing gene(s) for DCM. To explore the novel disease gene for DCM, we examined CRYAB encoding alphaB-crystallin for mutation in the patients with DCM, since alphaB-crystallin was recently reported to associate with the heart-specific N2B domain and adjacent I26/I27 domain of titin/connectin, and we previously reported a N2B mutation, Gln4053ter, in DCM. A missense mutation of CRYAB, Arg157His, was found in a familial DCM patient and the mutation affected the evolutionary conserved amino acid residue among alpha-crystallins. Functional analysis revealed that the mutation decreased the binding to titin/connectin heart-specific N2B domain without affecting distribution of the mutant crystallin protein in cardiomyocytes. In contrast, another CRYAB mutation, Arg120Gly, reported in desmin-related myopathy decreased the binding to both N2B and striated muscle-specific I26/27 domains and showed intracellular aggregates of the mutant protein. These observations suggest that the Arg157His mutation may be involved in the pathogenesis of DCM via impaired accommodation to the heart-specific N2B domain of titin/connectin and its disease-causing mechanism is different from the mutation found in desmin-related myopathy.

Aged↗
PubMed2006

Diagnostic significance of positive I-123 BMIPP despite negative stress Tl-201 myocardial imaging in patients with suspected coronary artery disease.

BACKGROUND: There is frequently discordance in the interpretation of myocardial single-photon emission computed tomography images using both rest iodine-123 15-(p-iodophenyl)-3-(R,S) methylpentadecanoic acid (BMIPP) and stress thallium-201 ((201)Tl); that is, negative BMIPP vs positive (201)Tl studies. However, little attention has been paid to reverse discordance (ie, positive BMIPP despite negative stress (201)Tl). METHODS AND RESULTS: In the present study 105 consecutive patients with suspected coronary artery disease (CAD) who underwent both rest BMIPP and stress (201)Tl imaging were evaluated. No patient with previous myocardial infarction was included. Scintigraphic studies revealed that BMIPP was in concordance with (201)Tl in 71 patients: both were positive in 38 and negative in 33, whereas both were discordant in 20 and reverse discordant in 14. In patients with reverse discordance, the pattern of BMIPP abnormality was segmental in 8 and spotty in 6; the former was related to coronary territory. Based on the BMIPP findings and clinical symptoms, 7 patients with positive BMIPP despite negative (201)Tl underwent coronary angiography: 3-vessel CAD was found in 3 patients, 2-vessel CAD in 1, coronary spasm in 2, and insignificant lesions in 1. In the remaining 7 patients, no cardiac event was observed during 2-year follow-up. CONCLUSIONS: In patients showing positive BMIPP despite negative (201)Tl, a segmental BMIPP perfusion abnormality indicates a high likelihood for CAD, despite normal stress (201)Tl imaging. Thus, adding BMIPP to (201)Tl imaging may help to better identify patients with significant CAD, including multivessel disease.

Aged↗
PubMed2005

Comparative value of brain perfusion SPECT and [(123)I]MIBG myocardial scintigraphy in distinguishing between dementia with Lewy bodies and Alzheimer's disease.

PURPOSE: Both decreased occipital perfusion on brain single-photon emission computed tomography (SPECT) and reduction in cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake are characteristic features of dementia with Lewy bodies (DLB), and potentially support the clinical diagnosis of DLB. The aim of this study was to compare the diagnostic value of these two methods for differentiation of DLB from Alzheimer's disease (AD). METHODS: The study population comprised 19 patients with probable DLB and 39 patients with probable AD who underwent both SPECT with N-isopropyl-p-[(123)I]iodoamphetamine and MIBG myocardial scintigraphy. Objective and quantitative measurement of perfusion in the medial occipital lobe, including the cuneus and lingual gyrus, was performed by the use of three-dimensional stereotactic surface projections. RESULTS: Medial occipital perfusion was significantly decreased in the DLB group compared with the AD group. The mean heart/mediastinum ratios of MIBG uptake were significantly lower in the DLB group than in the AD group. Although SPECT failed to demonstrate significant hypoperfusion in the medial occipital lobe in five patients with DLB, marked reduction of MIBG uptake was found in all patients with DLB. Receiver operating characteristic analysis revealed that MIBG myocardial scintigraphy enabled more accurate discrimination between DLB and AD than was possible with perfusion SPECT. CONCLUSION: MIBG myocardial scintigraphy may improve the sensitivity in the detection of DLB. In particular, this method may provide a powerful differential diagnostic tool when it is difficult to distinguish cases of DLB from AD using brain perfusion SPECT.

3-Iodobenzylguanidine↗
PubMed2005

Comparison of post-exercise and post-vasodilator stress myocardial stunning as assessed by electrocardiogram-gated single-photon emission computed tomography.

BACKGROUND: Exercise gated single-photon emission computed tomography (SPECT) using technetium-99m (99mTc)-sestamibi evaluates both myocardial perfusion during stress and wall motion >30 min after the stress, which has the potential to assess not only exercise-induced myocardial ischemia but also the development of myocardial stunning. METHODS AND RESULTS: To evaluate the incidence of post-stress myocardial stunning, as well as comparing the effects of different stress methods on the development of stunning, 179 consecutive patients with known or suspected coronary artery disease (CAD) underwent (99m)Tc-sestamibi SPECT with either exercise (n=135) or adenosine triphosphate disodium (ATP) (n=44). Electrocardiogram-gated SPECT images were acquired >30 min after the stress and again 4 h later, and perfusion and wall motion were evaluated. Post-stress myocardial stunning occurred in 24 patients (13%): 22 after exercise and 2 after ATP stress. The magnitude of the transient wall motion abnormality after exercise was greater in patients with severe ischemia, compared with those with mild-to-moderate ischemia (p<0.0001). By contrast, with ATP stress, the magnitude of the transient wall motion abnormality was similar, regardless of the severity of perfusion abnormality. Furthermore, a significant correlation between summed difference score and transient wall motion abnormality was found after exercise (r=0.68, p<0.0001). With ATP, however, no such correlation was observed (r=0.28, p=NS). CONCLUSIONS: Using 99mTc-sestamibi gated SPECT, myocardial stunning is frequently observed after exercise and correlates with the severity of myocardial ischemia, but this does not occur with ATP, which is regarded as a specific marker for severe CAD.

Adenosine Triphosphate↗
PubMed2005

Diagnostic value of simultaneous brachial and ankle blood pressure measurements for the extent and severity of coronary artery disease as assessed by myocardial perfusion imaging.

BACKGROUND: Although the simultaneous measurement of brachial and ankle blood pressure is a simple method of evaluating atherosclerosis, its diagnostic value for coronary artery disease (CAD) is undetermined. METHODS AND RESULTS: To evaluate the diagnostic value of ankle-brachial pressure index (ABI) and brachial-to-ankle pulse wave velocity (baPWV), 334 consecutive patients with suspected CAD were evaluated. Patients with a previous myocardial infarction or coronary intervention were not included. The magnitude of myocardial ischemia was evaluated by myocardial perfusion imaging. Using a 20-segment model, the percent of ischemic segments to total segments was expressed as %myocardium ischemic. In patients with < or =1, 2 and > or =3 coronary risk factors, %myocardium ischemic was 2.7+/-0.4, 4.0+/-0.5, 7.9+/-0.8%, respectively (p<0.0001 for trend). Performing ABI with a cutoff of 1, the %myocardium ischemic was similar in patients with < or =1 or 2 risk factors. In patients with > or =3 coronary risk factors, however, an ABI <1 reflected greater %myocardium ischemic than an ABI > or =1 (10.1+/-1.3, 6.6+/-1.0%; p=0.03). No such additional value was observed with baPWV. CONCLUSIONS: The addition of simultaneous brachial and ankle blood pressure measurements will help further stratify patients with multiple risk factors. Although this approach is simple, it facilitates the identification of high-risk patients who require aggressive treatment because >10% myocardium ischemic is regarded as a scintigraphic indicator for coronary revascularization.

Aged↗
PubMed2005

Value of pharmacologic stress myocardial perfusion imaging for preoperative risk stratification for aortic surgery.

BACKGROUND: Aortic surgery is an invasive, high-risk noncardiac procedure and the patients who require it have a high prevalence of coronary artery disease. Therefore, preoperative risk stratification for this subset is essential. METHODS AND RESULTS: To assess the perioperative risk for aortic surgery, pharmacologic stress single-photon emission computed tomography (SPECT) was performed in 302 patients: aortic dissection in 56, thoracic aortic aneurysm in 124, and abdominal aortic aneurysm in 122. Not only was the presence or absence of perfusion defects analyzed, but also the 20-segment model. Pharmacologic thallium SPECT revealed negative findings in 210 patients and positives in 92. Perioperative cardiac events occurred in 9 patients: 7 occurred in patients with positive SPECT, and in only 2 of those with negative SPECT (2/210 vs 7/92; p<0.05). Multivariate analysis using logistic regression model revealed that a summed stress score>or=14 was the most important factor to identify patients who subsequently had perioperative cardiac events. CONCLUSIONS: Pharmacologic stress SPECT has significant value in the risk stratification of patients before aortic surgery. In patients with positive SPECT, an aggressive approach to reduce the preoperative risk is necessary, whereas aortic surgery can be performed safely in patients with negative SPECT.

Aged↗
PubMed2005

Brachial -- ankle pulse wave velocity is a simple and independent predictor of prognosis in patients with acute coronary syndrome.

BACKGROUND: Although a very simple method of measuring brachial -- ankle pulse wave velocity (baPWV) has become available in a clinical setting, whether baPWV can predict future cardiovascular events remains uncertain. We examined whether baPWV is a predictor of cardiovascular events in patients with acute coronary syndrome (ACS). METHODS AND RESULTS: baPWV measurement was performed in 215 consecutive patients with ACS. During the follow-up period (26+/-10 months), 46 patients experienced post-hospitalization cardiovascular events (18 patients experienced a major event (eg, stroke, re-admission for heart failure or cardiac death), and 28 patients experienced coronary re-intervention). A receiver operating characteristic curve demonstrated that the best cut-off point of a baPWV for predicting a post-hospitalization cardiovascular event was 17.00 m/s and that for predicting a major cardiovascular event was 18.00 m/s. After the adjustment for the conventional risk factors influencing the prognosis, a multivariate Cox proportional hazards model demonstrated that both cut-off points of baPWV had a significant hazard ratio for a post-hospitalization event: 5.47 (2.69-11.09) and for a major cardiovascular event: 9.22 (2.78-30.56). CONCLUSIONS: baPWV is a simple predictor of the prognosis of patients with ACS that is independent of conventional risk factors for ACS.

Ankle↗
PubMed2004

Preoperative risk stratification for endovascular surgery using pharmacologic stress myocardial imaging.

To stratify perioperative cardiac risk for endovascular surgery, pharmacologic stress single-photon emission computed tomography (SPECT) was performed in 206 patients. Of 8 patients who had cardiac events, 7 occurred in 67 patients with positive SPECT results, whereas only 1 occurred in 139 patients with negative SPECT results (7 of 67 vs 1 of 139, p <0.002). Furthermore, a scintigraphic marker of a summed stress score >/=14 was the most important factor identifying patients who subsequently had cardiac events by multivariate analysis.

Aged↗
PubMed2004

Application of pressure-derived myocardial fractional flow reserve in assessing the functional severity of coronary artery stenosis in patients with diabetes mellitus.

BACKGROUND: Although the development of a coronary guidewire mounted with a pressure sensor has facilitated the measurement of pressure-derived fractional flow reserve (FFR) to assess the functional severity of coronary artery stenoses, the theoretical limitations include diabetes mellitus because of the associated microvascular abnormalities. METHODS AND RESULTS: In the present study 304 vessels and their coronary territories in 96 diabetic and 149 nondiabetic patients were evaluated by pressure-derived FFR and thallium-201 single photon emission computed tomography (SPECT) to determine the applicability of measuring FFR in diabetic subjects. The best cut-off value for FFR to detect myocardial ischemia, as demonstrated by (201)Tl SPECT, was 0.725 in the diabetic and 0.745 in the nondiabetic patients. Sensitivity and specificity were similar for the 2 groups (83% and 75% (diabetic) vs 79% and 83%). However, diabetic patients with homoglobin (Hb) A(1c) >or=7.0% showed lower specificity in comparison with those having HbA(1c) <7.0% (64 vs 88%; p=0.045); however, sensitivities were similar (83 vs 83%; p=NS). CONCLUSIONS: The cut-off value of 0.75 for FFR can detect myocardial ischemia in diabetic patients, although the adequacy of glycemic control should be taken into consideration when assessing the FFR measurements.

Aged↗
PubMed2004

Correlation between myocardial uptake of technetium-99m-sestamibi and pressure-derived myocardial fractional flow reserve.

OBJECTIVES: Development of the coronary pressure wire has facilitated the measurement of fractional flow reserve (FFR) to assess the functional severity of coronary artery stenoses. METHODS: This study evaluated the correlations between FFR and myocardial direct counts of technetium-99m(99mTc)-sestamibi in 20 patients (16 men, 4 women, mean age 66 +/- 8 years) who underwent 99mTc-sestamibi single-photon emission computed tomography (SPECT) with the 2-day protocol using 740 MBq of 99mTc-sestamibi each day. Visual assessment of myocardial imaging and quantitative analysis with the measurement of percent uptake and direct count of 99mTc-sestamibi were performed. RESULTS: Visual assessment of myocardial imaging revealed that reversibility of 99mTc-sestamibi perfusion defects was correlated with FFR of < 0.75, which is regarded as functionally important stenosis (17/20 vs 3/20, kappa = 0.71, p < 0.002). Regional reversibility score did not correlate with FFR (r = -0.40, p = NS). Quantitative analysis revealed that the change in 99mTc-sestamibi percent uptake with pharmacologic stress using adenosine triphosphate disodium (ATP) also did not correlate with FFR (r = 0.35, p = NS). In contrast, percent increase in 99mTc direct counts with ATP was lower in patients with FFR of < 0.75 than in those with FFR of > = 0.75 (-4 +/- 16% vs 24 +/- 30%, p < 0.01). In addition, a significant correlation (r = 0.70, p < 0.001) was observed between percent increase in 99mTc direct counts with ATP and FFR. CONCLUSIONS: These results suggest that quantitative analysis of 99mTc-sestamibi scintigraphy enables the assessment of the magnitude of functional significance of coronary stenosis.

Adenosine Triphosphate↗
PubMed2003

Reliability of pressure-derived myocardial fractional flow reserve in assessing coronary artery stenosis in patients with previous myocardial infarction.

In 167 patients with suspected coronary artery disease, 74 of whom had myocardial infarction (MI), measurement of myocardial fractional flow reserve (FFR) in previous infarction territories, using a cut-off point of 0.75, showed a sensitivity of 79% and a specificity of 79% for myocardial ischemia as demonstrated by thallium-201 myocardial imaging. This sensitivity and specificity were similar to a sensitivity of 79% and a specificity of 72% observed in territories not related to MI. In addition, a receiver-operating characteristic curve analysis revealed that the best predictability of FFR for myocardial ischemia was between 0.74 and 0.76, regardless of the presence or absence of MI.

Aged↗
PubMed2003

Influences of age and gender on results of noninvasive brachial-ankle pulse wave velocity measurement--a survey of 12517 subjects.

The present study was conducted to evaluate the influences of age and gender on the results of noninvasive brachial-ankle pulse wave velocity (baPWV). In 12517 subjects who had no medication and no history of cardiovascular diseases, multiple regression analysis demonstrated that age, blood pressure, body mass index, triglycerides, blood glucose, and uric acid were significant variables for baPWV in both genders. From this population, we extracted 7881 "healthy subjects" (4488 males and 3393 females, 25-87 years) without any of the atherogenic risk factors, and the results of baPWV were analyzed chronologically in 5-year age intervals. baPWV was lower in females than in males until age 60, and became similar in both genders over age 60. Multiple regression analysis demonstrated that not only the value of R(2) but also the coefficient of the effect of age on baPWV are larger in females than in males. In the estimation of the regression curve, the relationship between age and baPWV demonstrated a quadratic curve in both genders. Thus, aging influences baPWV, and its effect is more prominent in female. Menopause seems to be the crucial phenomenon to explain the augmented increase in arterial stiffness with aging in females.

Adult↗
PubMed2003

Beneficial effect of coronary artery bypass grafting as assessed by quantitative gated single-photon emission computed tomography.

The development of quantitative gated single-photon emission computed tomography (SPECT) has enabled the assessment of left ventricular perfusion, function and wall thickness in a single examination. Accordingly, the present study used gated SPECT to assess the benefit of coronary artery bypass grafting (CABG) in patients with coronary artery disease; 47 of those patients were evaluated before and 5 months after CABG. As a result of coronary revascularization, a significant improvement was observed in global ejection fraction (50+/-12 --> 53+/-11%; p<0.05). In 107 revascularized territories, the average regional reversible defect score (0.8+/-0.5 --> 0.2 +/-0.3; p<0.0001), average regional perfusion score at rest (0.6+/-0.6 --> 0.3+/-0.4; p<0.0001), average regional wall motion score (0.9+/-0.7 --> 0.7+/-0.5; p<0.05), and end-diastolic wall thickness (8.1+/-1.3 --> 8.6+/-1.5 mm; p<0.0005) all improved significantly. Even in 34 non-revascularized territories, the average regional reversible defect score (0.5+/-0.7 --> 0.2+/-0.5; p<0.03), average regional wall motion score (0.8+/-1.1 --> 0.5 +/-1.0; p<0.03) and end-diastolic wall thickness (8.0+/-1.4 --> 9.1+/-2.0 mm; p<0.03) all improved significantly. These results indicate that improvement in myocardial ischemia, hibernation and left ventricular function with CABG can be assessed in detail with gated SPECT.

Aged↗
PubMed2003

[Long-term effect of hypertension on neurobehavioral and cardiac function in the apparently healthy community-dwelling elderly: a 5-year follow-up study].

Recently, it has been reported that hypertension causes not only cerebro-cardiovascular diseases, but also a decline of cognitive function in the elderly. However, it is not clear whether or not aging and hypertension have a latent effect on the cognitive-neurobehavioral and cardiac functions in healthy elderly whose scores of basic activities of daily living (ADL) are fully maintained. We evaluated the effect of aging and hypertension on cognitive-neurobehavioral and cardiac functions in 25 healthy community-dwelling elderly subjects (mean age: 69 y.o.) whose scores of basic ADL were fully maintained. Subjects were followed over a 5-year period, and the following examinations were performed before and after a 5-year follow-up: echocardiography, 24-hr ambulatory blood pressure monitoring (ABPM), and cognitive-neurobehavioral function test. Left ventricular mass index was significantly increased in the hypertensive (HT) subjects relative to the normotensive (NT) subjects over the 5 years (% change: 3% for HT vs. -0.8% for NT, p = 0.03). The number of non-dippers significantly increased over the 5 years in the HT group (initially: 20% [2/10] vs. follow-up: 58% [7/12], p = 0.04). Visuospatial cognitive performance scale scores for evaluation of higher cognitive-neurobehavioral functions significantly deteriorated in the HT subjects (initially; 2,344 +/- 110 vs. 2,380 +/- 102, ns, and follow-up: 2,149 +/- 181 vs. 2,356 +/- 159, p = 0.04). Hypertension contributes to the impairment of the cognitive-neurobehavioral function in the elderly by latently affecting the functions of multiple organs. This occurs even if basic ADL is maintained for 5 years. Therefore, it is important to control BP not only to prevent cardiovascular events, but also to preserve the neurobehavioral function.

Activities of Daily Living↗