Shiro Nakamori

Computed tomography angiography and perfusion to assess coronary artery stenosis causing perfusion defects by single photon emission computed tomography: the CORE320 study

AIMS To evaluate the diagnostic power of integrating the results of computed tomography angiography (CTA) and CT myocardial perfusion (CTP) to identify coronary artery disease (CAD) defined as a flow limiting coronary artery stenosis causing a perfusion defect by single photon emission computed tomography (SPECT). METHODS AND RESULTS We conducted a multicentre study to evaluate the accuracy of integrated CTA-CTP for the identification of patients with flow-limiting CAD defined by ≥50% stenosis by invasive coronary angiography (ICA) with a corresponding perfusion deficit on stress single photon emission computed tomography (SPECT/MPI). Sixteen centres enroled 381 patients who underwent combined CTA-CTP and SPECT/MPI prior to conventional coronary angiography. All four image modalities were analysed in blinded independent core laboratories. The prevalence of obstructive CAD defined by combined ICA-SPECT/MPI and ICA alone was 38 and 59%, respectively. The patient-based diagnostic accuracy defined by the area under the receiver operating characteristic curve (AUC) of integrated CTA-CTP for detecting or excluding flow-limiting CAD was 0.87 [95% confidence interval (CI): 0.84-0.91]. In patients without prior myocardial infarction, the AUC was 0.90 (95% CI: 0.87-0.94) and in patients without prior CAD the AUC for combined CTA-CTP was 0.93 (95% CI: 0.89-0.97). For the combination of a CTA stenosis ≥50% stenosis and a CTP perfusion deficit, the sensitivity, specificity, positive predictive, and negative predicative values (95% CI) were 80% (72-86), 74% (68-80), 65% (58-72), and 86% (80-90), respectively. For flow-limiting disease defined by ICA-SPECT/MPI, the accuracy of CTA was significantly increased by the addition of CTP at both the patient and vessel levels. CONCLUSIONS The combination of CTA and perfusion correctly identifies patients with flow limiting CAD defined as ≥50 stenosis by ICA causing a perfusion defect by SPECT/MPI.

Serum intact parathyroid hormone levels predict hospitalisation for heart failure

Objective: To assess whether circulating levels of intact parathyroid hormone (intact PTH) in outpatients predict hospitalisation for heart failure (HF). Methods: Eighty-eight consecutive outpatients with HF were enrolled in the study. The independent association between intact PTH and hospitalisation for HF was assessed using Cox regression analysis. Results: Mean (SD) serum intact PTH levels significantly increased as New York Heart Association classes increased (I: 40 (21), II: 55 (24), III: 76 (46), IV: 131 (45) pg/ml). The receiver operating characteristic (ROC) curves showed intact PTH levels ⩾47 pg/ml to be the optimal cut-off points for hospitalisation for HF, with sensitivity 87%, specificity 71% and area under the ROC curve 0.82 (95% CI 0.72 to 0.91). After adjustment for variables accepted to be predictors for hospitalisation due to HF (age, gender, hypertension, diabetes mellitus, atrial fibrillation, ischaemic heart disease, left ventricular ejection fraction, B-type natriuretic peptide, estimated glomerular filtration rate and cardiac drugs), intact PTH levels ⩾47 pg/ml were associated with a hazard ratio of 7.13 for hospitalisation for HF (95% CI 1.79 to 28.4). Conclusion: Serum intact PTH levels obtained in outpatients with HF were shown to be an independent predictor of hospitalisation for HF.

Diagnostic Accuracy of 1.5-T Unenhanced Whole-Heart Coronary MR Angiography Performed with 32-Channel Cardiac Coils: Initial Single-Center Experience

PURPOSE To compare the imaging time and image quality obtained with whole-heart coronary magnetic resonance (MR) angiography performed with five- and 32-channel coils in healthy subjects and determine the accuracy of MR angiography performed with 32-channel coils in the detection of obstructive coronary artery disease (CAD). MATERIALS AND METHODS The institutional review board approved the study protocol, and all participants provided written informed consent. The authors studied 10 healthy subjects and 67 patients suspected of having CAD who were scheduled for coronary angiography. Unenhanced 1.5-T coronary MR angiography was performed with five- and 32-channel coils in healthy subjects and with 32-channel coils in patients. Clinically significant CAD was defined as a diameter reduction of at least 50% at coronary angiography. The sensitivity and specificity of coronary MR angiography were calculated. RESULTS The mean imaging time was substantially reduced from 12.3 minutes ± 4.2 (standard deviation) with five-channel coils to 6.3 minutes ± 2.2 with 32-channel coils, with equivalent image quality scores. Acquisition of MR angiograms was completed in all 67 patients, with a mean imaging time of 6.2 minutes ± 2.8. The prevalence of CAD in the study population was 58% (39 of the 67 patients). The areas under the receiver operating characteristic curves as determined at vessel- and patient-based analyses were 0.91 and 0.90, respectively; the sensitivity and specificity at vessel-based analysis were 86% and 93%, respectively. CONCLUSION Whole-heart coronary MR angiography performed at 1.5 T with 32-channel coils permits noninvasive detection of CAD with substantially reduced imaging time. This noninvasive approach can be an alternative to multidetector computed tomographic coronary angiography for ruling out obstructive CAD in patients who have a contraindication to contrast material and in young subjects who are at higher risk from ionizing radiation. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101323/-/DC1.

Short-term effects of low-dose tolvaptan on hemodynamic parameters in patients with chronic heart failure

BACKGROUND We evaluated the short-term effects of low-dose tolvaptan treatment on hemodynamic parameters in patients with chronic heart failure (HF). METHODS We studied 22 patients (69 ± 10 years) with chronic HF and excess fluid retention despite receiving appropriate medical therapy, including loop and/or thiazide diuretics. The therapeutic effects of low-dose (7.5mg) once-daily tolvaptan on hemodynamics associated with changes in fluid balance and neurohumoral activations were investigated after a seven day treatment period. RESULTS After the treatment period, body weight decreased (-2.7 ± 2.3 kg) associated with increases in daily urine output. Whereas plasma arginine-vasopressin levels, serum aldosterone concentration, and plasma renin activity mildly increased, plasma levels of B-type natriuretic peptide and atrial natriuretic peptide significantly decreased after tolvaptan treatment. Serum electrolytes were not adversely affected by tolvaptan treatment. Although cardiac index and systemic vascular resistance index remained unchanged, mean pulmonary artery wedge pressure (22 ± 7 mmHg vs. 17 ± 7 mmHg, p<0.05), mean right atrial pressure (12 ± 5 mmHg vs. 9 ± 5 mmHg, p<0.05), mean pulmonary artery pressure (32 ± 9 mmHg vs. 25 ± 7 mmHg, p<0.05), and pulmonary vascular resistance index (332 ± 207 dynes/cm(-5)/m(2) vs. 245 ± 110 dynes/cm(-5)/m(2), p<0.05) significantly decreased after tolvaptan treatment. The extent of the reduction in pulmonary vascular resistance index after tolvaptan treatment strongly correlated with baseline values. CONCLUSIONS Short-term treatment with low-dose tolvaptan improved hemodynamic parameters and correlated with significant fluid removal in patients with chronic HF.

Quantitative Analysis of 1.5-T Whole-Heart Coronary MR Angiograms Obtained with 32-Channel Cardiac Coils: A Comparison with Conventional Quantitative Coronary Angiography

PURPOSE To develop a method to determine significant stenosis at whole-heart coronary magnetic resonance (MR) angiography and to evaluate the accuracy and reproducibility of this approach. MATERIALS AND METHODS The institutional review board approved the study, and all participants provided written informed consent. Sixty-two patients who were suspected of having coronary artery disease (CAD) and were scheduled for conventional coronary angiography were included. Coronary MR angiography was performed by using a 1.5-T imager with 32-channel coils. Luminal narrowing was evaluated with quantitative analysis (QA) of coronary MR angiograms on the basis of the signal intensity profile along the vessel. Percentage stenosis with QA of coronary MR angiograms was calculated as [1 - (SI(min)/SI(ref))] × 100, where SI(min) is minimal signal intensity and SI(ref) is corresponding reference signal intensity. Diagnostic performance of QA of coronary MR angiograms for predicting at least a 50% reduction in diameter was evaluated by using quantitative coronary angiography (QCA), with conventional angiography findings serving as the reference standard. Receiver operating characteristic (ROC) analysis, Spearman rank correlation, Bland-Altman analysis, and Cohen κ analysis were used. RESULTS The areas under the ROC curve in a segment-based analysis for detecting significant CAD were 0.96 (95% confidence interval [CI]: 0.94, 0.98) with QA of coronary MR angiograms and 0.93 (95% CI: 0.88, 0.98) with visual assessment. The correlation coefficients between percentage stenosis with QA of coronary MR angiograms and percentage stenosis with QCA were 0.84 (P < .001), 0.80 (P < .001), and 0.66 (P < .001) in the patient-, vessel-, and segment-based analyses, respectively. CONCLUSION QA of coronary MR angiograms with use of a signal intensity profile along the vessel permits detection of CAD. This method had a diagnostic performance approximately equal to that of visual analysis of coronary MR angiograms with high inter- and intraobserver reliability, allowing for more objective interpretation of coronary MR angiography findings.

Interrelationship between haemodynamic state and serum intact parathyroid hormone levels in patients with chronic heart failure

Objective To assess the impact of serum intact parathyroid hormone (PTH) levels on haemodynamic state and their relations by comparing plasma B-type natriuretic peptide (BNP) levels. Design Cross-sectional study in molecular epidemiology. Setting Mie University Hospital, Tsu, Japan. Patients Consecutive 105 patients with chronic heart failure (CHF). Main outcome measures Serum intact PTH and plasma BNP levels were assessed simultaneously with right heart catheterisation. Results Although serum intact PTH levels (46±25 pg/ml) were within the normal range (<65 pg/ml) in 87% of patients, log-transformed intact PTH levels significantly correlated with pulmonary capillary wedge pressure (PCWP: 15±9 mm Hg, r=0.55, p<0.05) and heart rate (73±14/min, r=0.40, p<0.05), whereas log-transformed intact PTH levels were inversely correlated with stroke volume index (SVI: 38±11 ml/m2, r=−0.52, p<0.05) and cardiac index (2.6±0.7 l/min/m2, r=−0.41, p<0.05) in all patients. PCWP and SVI were independent determinants of log-transformed intact PTH levels (β=0.40 and −0.37, p<0.05, respectively) after adjusting for variables associated with PTH. Conversely, after adjusting for variables associated with CHF, log-transformed intact PTH levels were an independent determinant of PCWP, SVI, heart rate and cardiac index (β=0.38, −0.33, 0.32, and −0.25, p<0.05, respectively), and might be defined as a superior determinant of SVI and cardiac index compared with log-transformed BNP levels using stepwise multivariate regression analyses. Conclusions Increased PCWP and decreased SVI independently contribute to elevated intact PTH in patients with CHF.

Myocardial delayed enhancement with dual-source CT: Advantages of targeted spatial frequency filtration and image averaging over half-scan reconstruction

BACKGROUND Clinical utility of myocardial delayed-enhancement CT is currently limited because of relatively poor contrast-to-noise ratio (CNR) and artifacts. Targeted spatial-frequency filtration (TSFF) is a hybrid algorithm of half- and full-scan reconstruction that can achieve both high temporal resolution and improved stability of myocardial signal. OBJECTIVE The purpose of this study was to evaluate image quality of delayed-enhancement CT using TSFF with image averaging and its reproducibility in infarct assessment in comparison with conventional half-scan reconstruction (HALF). METHODS Forty patients with suspected coronary artery disease underwent delayed-enhancement CT with HALF and TSFF using dual-source CT. Two blinded readers independently determined the presence and size of delayed enhancement. Image quality, signal-to-noise ratio and CNR were assessed. The presence of delayed enhancement on CT was compared with magnetic resonance imaging in 12 patients. RESULTS TSFF with averaging of 4 image stacks acquired during 1 breathhold demonstrated significantly better image quality compared with HALF. Good left ventricular lumen-myocardium contrast was consistently achieved with TSFF in patients who received iodine dose of >600 mg I/kg. The signal-to-noise ratio and CNR were 11.3 ± 4.2 and 4.5 ± 1.6 by TSFF, being significantly higher than those by HALF (7.9 ± 2.9 and 3.3 ± 1.8; P < .01 for both). Interobserver reproducibility of infarct sizing was markedly improved by using TSFF instead of HALF (intraclass correlation coefficient: 0.86 vs 0.50). Agreement with magnetic resonance imaging by kappa statistics was 0.85 with TSFF and 0.74 with HALF. CONCLUSIONS TSFF with image averaging can significantly improve image quality of delayed-enhancement CT and considerably enhances interobserver reproducibility of infarct sizing.

Quantifying longitudinal right ventricular dysfunction in patients with old myocardial infarction by using speckle-tracking strain echocardiography

BackgroundWe investigated longitudinal right ventricular (RV) function assessed using speckle-tracking strain echocardiography in patient with myocardial infarction (MI), and identified the contributing factors for RV dysfunction.MethodsWe retrospectively studied 71 patients with old MI (the OMI group) and 45 normal subjects (the Control group) who underwent a transthoracic echocardiography. Global and free wall RV peak systolic strains (PSSs) in the longitudinal direction were measured by using speckle-tracking strain echocardiography. Left ventricular (LV) PSSs were measured in the longitudinal, radial and circumferential directions. Cardiac hemodynamics including peak systolic pulmonary artery pressure was also assessed non-invasively. Plasma brain natriuretic peptide (BNP) levels were measured in all patients.ResultsIn the OMI group, 73% of the patients had a normal estimated peak systolic pulmonary artery pressure of less than 35 mmHg. Global and free wall RV PSS were impaired in the OMI group compared with the Control group, and these RV systolic indices were significantly associated with heart rate, logarithmic transformed plasma BNP, greater than 1 year after onset of MI, Doppler-derived estimated pulmonary vascular resistance, LV systolic indices, LV mass index, infarcted segments within a territory of the left circumflex artery and residual total occlusion in the culprit right coronary artery. Multivariable linear regression analysis indicated that reduced longitudinal LV PSS in the 4-chamber view and BNP levels ≥500 pg/ml were independently associated with reduced global and free wall RV PSS. Moreover, when patients were divided into 3 groups according to plasma BNP levels (BNP <100 pg/ml; n = 31, 100 ≤BNP <500 pg/ml; n = 24, and BNP ≥500 pg/ml; n = 16), only patients with BNP ≥500 pg/ml had a strong correlation between RV PSS and longitudinal LV PSS in the 4-chamber view (r = 0.78 for global RV PSS and r = 0.71 for free wall RV PSS, p <0.05).ConclusionLongitudinal RV systolic strain depends significantly on longitudinal LV systolic strain especially in patients with high plasma BNP levels, but not on estimated peak systolic pulmonary artery pressure. These results indicate that process of RV myocardial dysfunction following MI may be governed by neurohormonal activation which causing ventricular remodeling rather than increased RV afterload.

Native T1 mapping in patients with idiopathic dilated cardiomyopathy for the assessment of diffuse myocardial fibrosis: validation against histologic endomyocardial biopsy

Background Late gadolinium enhancement (LGE) MRI provides a significant impact on prognosis in dilated cardiomyopathy (DCM) patients. However, LGE MRI is less suitable for quantifying the degree of fibrosis in diffusely diseased myocardium. T1 mapping technique allows for the quantitative assessment of extracellular volume fraction (ECV), which has been histologically validated against the collagen volume fraction (CVF). Native myocardial T1 also has a potential for the noninvasive detection of myocardial fibrosis. Recent study demonstrated that native myocardial T1 permits the discrimination between normal and diffusely diseased myocardium accurately in DCM patients. However, in-vivo histological validation of native myocardial T1 in DCM patients is still lacking. The aim of this study was to histologically validate native myocardial T1 for the assessment of diffuse myocardial fibrosis in DCM patients.

Detection of Coronary Artery Disease Using Coronary Flow Velocity Reserve by Transthoracic Doppler Echocardiography versus Multidetector Computed Tomography Coronary Angiography: Influence of Calcium Score

BACKGROUND There have been no clinical data specifying the degree of calcium deposition at which coronary flow velocity reserve (CFVR) measurement using transthoracic Doppler echocardiography surpasses 320-row multidetector computed tomographic coronary angiography (CTCA) in detecting obstructive coronary artery disease. METHODS One hundred seventy patients who underwent invasive coronary angiography, transthoracic Doppler echocardiography, and CTCA were prospectively enrolled. Coronary artery stenosis was defined as percentage diameter stenosis ≥ 50% on invasive coronary angiography. CFVR < 2.0 and narrowing ≥ 50% measured with CTCA were the thresholds indicating the presence of coronary artery stenosis. The degree of coronary artery calcification was also assessed using the Agatston calcium score method by computed tomography. RESULTS The majority of patients (89%) were classified as having either high or intermediate pretest probability of coronary artery disease. Significant coronary artery stenoses by invasive coronary angiography were found in 71 patients and 104 vessels. Although the overall diagnostic performance of CTCA was comparable with that of CFVR measurement for detecting coronary artery stenosis, only the diagnostic performance of CTCA was negatively affected by the extent of a patients coronary artery calcification. Receiver operating characteristic curve analysis indicated that only CFVR measurement is diagnostically accurate when calcium scores are >319 in the patient-based assessment, 189 for the left anterior descending coronary artery, 98 for the left circumflex coronary artery and 282 for the right coronary artery. CONCLUSIONS Transthoracic Doppler echocardiography and 320-row multidetector CTCA successfully diagnosed significant coronary artery stenosis with high feasibility and accuracy. However, only the diagnostic performance of CTCA was negatively affected by the extent of a patients coronary artery calcification, and therefore the diagnostic performance of CFVR measurement for detecting coronary artery stenosis surpassed that of CTCA when the calcium score exceeded specified cutoff values.