Satoshi Hida

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 123I-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.

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.

Prevalence of Coronary Heart Disease in Patients With Aortic Aneurysm and/or Peripheral Artery Disease

Although the presence of coronary heart disease (CHD) was the major determinant of perioperative mortality and long-term prognosis in patients with aortic aneurysm (AA) and peripheral artery disease (PAD), the prevalence and severity of CHD in patients with individual vascular diseases was unknown. Adenosine triphosphate-loading myocardial single-photon emission computed tomography therefore was performed in 788 patients with vascular diseases of the aorta and peripheral arteries, with AA in 500, PAD localized in the lower-limb arteries in 183, and combined AA and PAD in 105. Patients with known CHD, such as those with previous myocardial infarction or revascularization procedures, were excluded. Myocardial single-photon emission computed tomography was analyzed using a 20-segment model, and summed stress scores and summed difference scores were calculated. Stress-induced myocardial ischemia was defined as a summed difference score >or=2. The presence of myocardial ischemia was highest in patients with combined PAD and AA (73%), followed by PAD (55%; p = 0.005), and the lowest in patients with AA (37%; p <0.0001). Summed stress score was also the highest in patients with combined PAD and AA (11.6 +/- 9.9), followed by PAD (7.8 +/- 8.8; p <0.0001), and the lowest in patients with AA (4.0 +/- 6.2; p <0.0001 for both). Similarly, summed difference score was the highest in patients with combined PAD and AA (6.4 +/- 6.1), followed by PAD (4.4 +/- 5.7; p = 0.001) and AA (2.3 +/- 4.0; p <0.0001 for both). In conclusion, the prevalence of CHD in patients with PAD was >50%, and although myocardial ischemia was observed in only (1/3) of patients with AA, its prevalence not only doubled, but also indicated extensive myocardial ischemia when combined with PAD. Thus, cardiac evaluation was particularly important in patients with combined AA and PAD.

Effect of percutaneous coronary angioplasty on myocardial perfusion, function, and wall thickness as assessed by quantitative gated single-photon emission computed tomography

In conclusion, improvement in myocardial ischemia, hibernation, and left ventricular function with coronary revascularization can be assessed in detail by applying gated SPECT. In particular, the beneficial effects were demonstrated, even in non-revascularized territories, through good collateral circulation in which blood flow was improved by revascularization.

Important parameters in the detection of left main trunk disease using stress myocardial perfusion imaging

OBJECTIVES We sought noninvasively to diagnose left main trunk (LMT) disease using myocardial perfusion imaging (MPI). METHODS Five hundred and eight patients with suspected coronary artery disease (CAD) underwent both stress MPI and coronary angiography. The extent and severity of perfusion abnormalities were assessed using a 20-segment model. In addition, perfusion defects in both left anterior descending and left circumflex arterial territories were defined as a left main (LM) pattern defect, and those in 3-coronary arterial territories as a 3-vessel pattern defect. RESULTS In 42 patients with LMT disease, a summed stress score (19.4 ± 10.0 vs. 13.5 ± 10.0; p < 0.0001) and a summed rest score (12.1 ± 9.7 vs. 7.0 ± 7.8; p = 0.002) were greater than in 466 patients without LMT disease, while a summed difference score was similar (7.3 ± 7.7 vs. 6.5 ± 6.1; p = NS). The prevalence of an LM-pattern defect was low in both groups (12% vs. 8%; p = NS). However, a 3-vessel pattern defect (33% vs. 7%; p < 0.0001), lung uptake of radiotracers (38% vs. 11%; p < 0.0001), and transient ischemic dilation (31% vs. 13%; p = 0.003) were more frequently observed in patients with LMT disease than in those without. Logistic regression analysis showed that a 3-vessel pattern defect (OR=3.5, 95% CI = 1.4-8.8; p = 0.007), lung uptake of radiotracers (OR = 2.5, 95% CI = 1.1-5.7; p = 0.03), and previous myocardial infarction (MI) (OR = 2.4, 95% CI = 1.0-5.7; p = 0.05) were the most important parameters to detect LMT disease. After excluding 163 patients with previous MI, a repeat analysis revealed that lung uptake of radiotracers (OR = 8.2, 95% CI = 2.3-29.2; p = 0.001) and an LM-pattern defect (OR = 6.3, 95% CI = 1.4-27.2; p < 0.02) were independent predictors for LMT disease. CONCLUSION In the identification of LMT disease, lung uptake of radiotracers was a single best parameter, which was independent of the presence or absence of previous MI.

Differential effects comparing exercise and pharmacologic stress on left ventricular function using gated Tc-99m sestamibi SPECT

ObjectiveAlthough post-ischemic stunning has emerged as an important marker for severe coronary artery disease (CAD), differences in stress methods may have different effects on left ventricular (LV) volumes and function.MethodsTo assess differential effects comparing exercise and pharmacologic stress on the LV measurements, 99mTc-sestamibi gated single-photon emission computed tomography (SPECT) acquired more than 30 min after stress and at rest was evaluated in 38 patients undergoing adenosine triphosphate (ATP) stress (ATP group) and 38 age-and sex-matched patients subjected to exercise stress (Ex group) among 268 patients with normal SPECT findings.ResultsCoronary risk factors and LV volumetric measurements at baseline were similar in the two groups. Compared with volumetric measurements at rest, enddiastolic volume (EDV) increased (72 ± 21 ml to 74 ± 21 ml; P = 0.01), end-systolic volume increased (25 ± 12 ml to 28 ± 13 ml; P = 0.001), and ejection fraction (EF) decreased after stress (66% ± 8% to 63% ± 9%; P < 0.002) in the ATP group. In the Ex group, by contrast, no such change was observed. In addition, changes in EDV (3 ± 6 vs. −1 ± 5 ml; P = 0.01) and the stress-to-rest ratio of EDV (1.04 ± 0.09 vs. 0.99 ± 0.08; P < 0.02) after stress were greater in the ATP than in the Ex group.ConclusionsDifferential effects of stress methods on LV volumes persist more than 30 min after the stress. These findings should be kept in mind when interpreting post-ischemic stunning.

High-tension electrical injury to the heart as assessed by radionuclide imaging

To evaluate cardiac complications associated with electrical injury, 7 patients with high-tension electrical injury (6,600 V alternating current) underwent201Tl and123I-metaiodobenzylguanidine (MIBG) imaging in addition to conventional electrocardiographic and echocardiographic assessments. Electrocardiography showed transient atrial fibrillation, second degree atrioventricular block, ST-segment depression, and sinus bradycardia in each patient. Echocardiography showed mild hypokinesis of the anterior wall in only 2 patients, but201Tl and123I-MIBG myocardial scintigraphy whowed an abnormal scan image in 6/7 and 5/6 patients, respectively. Decreased radionuclide accumulation was seen primarily in areas extending from the anterior wall to the septum. Decreased radionuclide accumulation was smaller in extent and milder in degree in123I-MIBG than in201Tl imaging. These results suggest that even in patients without definite evidence of severe cardiac complications in conventional examinations, radionuclide imaging detects significant damage due to high-tension electrical injury, in which sympathetic nerve dysfunction might be milder than myocardial cell damage.

Diagnostic value of vasodilator-induced left ventricular dyssynchrony as assessed by phase analysis to detect multivessel coronary artery disease

Purpose: Phase analysis was recently developed to allow left ventricular(LV)mechanical dyssynchrony to be assessed by gated single-photon emission computed tomography(SPECT) . However, few studies have analyzed LV dyssynchrony during pharmacological stress and at rest by applying phase analysis to detect multivessel coronary artery disease(CAD)using the SyncTool TM . Methods: Adenosine triphosphate(ATP)loading electrocardiogram-gated 99m Tc-sestamibi SPECT was performed on 180 patients with suspected or known CAD. LV dyssynchrony was evaluated using the SyncTool TM ; the phase standard deviation(SD)and histogram bandwidth were derived. Results: The summed stress score(SSS) , summed difference score(SDS) , post-stress increase in phase SD, and histogram bandwidth were greater in 78 patients with multivessel CAD than in 102 patients with insignificant or single-vessel CAD. In the detection of multivessel CAD, SSS of >9 and SDS of >5 showed sensitivities of 74% and 74%,and specificities of 71% and 78% respectively, whereas an increase in phase SD>8.3°and in histogram bandwidth >16°after ATP loading had sensitivities of 62% and 74% and specificities of 77% and 68%, respectively. A multivariate logistic analysis revealed that the identification of multivessel CAD was superior with the combination of a post-ATP increase in phase SD, increase in histogram bandwidth, and SDS(sensitivity 82%, specificity 76%, chi-square=80.0)than with SDS alone (sensitivity 74%, specificity 78%, chi-square=58.9) . Conclusion: The addition of ATP-induced LV dyssynchrony parameters to conventional perfusion analysis enabled the superior identification of patients with multivessel CAD.

A flow-limiting stenosis is the major determinant of exercise-induced myocardial stunning in patients with coronary artery disease

BACKGROUND Although stress-induced myocardial stunning often develops after exercise testing, determinants of this phenomenon have not been evaluated. METHODS AND RESULTS Thirty-one patients with 1-vessel coronary artery disease, limited to the left anterior descending artery (LAD), were evaluated by quantitative coronary angiography (QCA) and intracoronary pressure measurements to calculate fractional flow reserve (FFR). In addition, electrocardiogram-gated technetium-99m sestamibi myocardial imaging was acquired >30 min after exercise and 4 h later to assess the development of stunning. Exercise-induced myocardial stunning was observed in 11 patients (35%). In patients with myocardial stunning, a summed stress score (17.3+/-7.1 vs. 8.1+/-6.2, p<0.001), summed difference score (10.3+/-4.1 vs. 2.7+/-1.9, p<0.0001), and wall motion difference score (4.8+/-2.8 vs. 0.9+/-1.1, p<0.0001) were greater than in those without, while diameter stenosis calculated by QCA (55.1+/-17.3% vs. 29.8+/-17.3%, p<0.0001) was greater and FFR reduced significantly (0.54+/-0.13 vs. 0.83+/-0.06, p<0.0001). Of note, 4 out of 21 patients (19%) with <50% LAD stenosis developed myocardial stunning, whereas only one patient with FFR of 0.64 or greater showed stunning. The best cut-off value was determined as 0.64 for FFR and 46% for QCA, providing 91% sensitivity and 100% specificity for FFR (chi-square=57.2), but 91% sensitivity and 80% specificity for diameter stenoses measured by QCA (chi-square=17.8). CONCLUSIONS The major determinant for exercise-induced myocardial stunning was a severe flow-limiting coronary stenosis, which was more important than anatomical evaluation based on luminal narrowing alone.

Diagnostic Performance of a Cadmium-Zinc-Telluride Single-Photon Emission Computed Tomography System With Low-Dose Technetium-99m as Assessed by Fractional Flow Reserve

BACKGROUND Although stress single-photon emission computed tomography (SPECT) using a cadmium-zinc-telluride (CZT) camera facilitates radiation dose reduction, only a few studies have evaluated its diagnostic accuracy in Japanese patients by applying fractional flow reserve (FFR) measurements. METHODSANDRESULTS We prospectively evaluated 102 consecutive patients with suspected or known coronary artery disease with a low-dose stress/rest protocol ((99m)Tc radiotracer 185/370 MBq) using CZT SPECT. Within 3 months, coronary angiography was performed and a significant stenosis was defined as ≥90% diameter narrowing on visual estimation, or as a lesion of <90% and ≥ 50% stenosis with FFR ≤0.80. To detect individual coronary stenosis, the respective sensitivity, specificity, and accuracy were 86%, 75%, and 82% for left anterior descending artery stenosis, 76%, 81%, and 79% for left circumflex artery stenosis, and 87%, 92%, and 90% for right coronary artery stenosis. When limited to 92 intermediate stenotic lesions in which FFR was measured, stress SPECT showed 77% sensitivity, 91% specificity, and 84% accuracy, whereas the diagnostic value decreased to 52% sensitivity, 68% specificity, and 58% accuracy based only on visual estimation of ≥75% diameter narrowing. CONCLUSIONS CZT SPECT demonstrated a good diagnostic yield in detecting hemodynamically significant coronary stenoses as assessed by FFR, even when using a low-dose (99m)Tc protocol with an effective dose ≤5 mSv. (Circ J 2016; 80: 1217-1224).