Kumiko Konno

Impact of 16-slice computed tomography in percutaneous coronary intervention of chronic total occlusions

The main reason for failure of percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) is because the calcified plaque prevents the guide wire crossing the occlusion. We aimed to identify the route, and characterize plaque components within CTO, using 16‐slice computed tomography (MSCT). Twenty three angiographic CTO in 22 patients (mean age 69 ±± 5 years, 17 males) were included. All patients had undergone MSCT prior to PCI. Images were analyzed for lesion visibility and plaque characteristics of CTO. The presence and location of calcified plaque within the CTO were systematically assessed. Each lesion was classified as a noncalcified, moderately calcified, or exclusively calcified plaque. Procedural failure was defined as the inability to cross a guide wire through the occlusion. All coronary routes of CTO segment were visualized. MSCT revealed three markedly bent CTO segments (13.0%), which could not be identified by coronary angiography only. Calcified plaques were detected in 30 lesions of 19 CTO segments (82.6%), but were not detected in the other four. The majority of calcified plaque was located in the proximal lesion, or both proximal and distal lesions. Fifteen out of 30 calcified lesions (50.0%) were exclusively calcified plaques. Overall procedural success was obtained in 21 CTOs (91.3%). MSCT can accurately identify the route of the CTO segment and evaluate both distribution and amount of the calcified plaque within it. Even with the complicated and/or calcified lesions, PCI success rate was excellent under MSCT guidance. MSCT should become a useful tool in PCI of CTO.

Accuracy of attenuation measurement of vascular wall in vitro on computed tomography angiography: Effect of wall thickness, density of contrast medium, and measurement point.

Objectives:We sought to assess the effects of measurement point, wall thickness, and intravascular density of contrast material on attenuation measurement of vascular wall. Materials and Methods:We used vascular models (actual attenuation value of the wall: 83 HU) with wall thicknesses of 1.5, 1.0, or 0.5 mm, filled with contrast material of 254, 325, or 400 HU. The 9 vascular models were fixed in an oil-filled container and scanned with a 16-detector computed tomography. The wall attenuation values were measured at 1 point for 0.5-mm thickness models, 3 for 1.0-mm thickness models, and 5 for 1.5-mm thickness models with the same interval of 0.25 mm. Total 20 measurements were done for each point. Results:For 1.0-mm and 1.5-mm thickness models, wall attenuation progressively increased as the measurement points approached the lumen (P < 0.0001). At all the measurement points for 0.5-mm and 1.0-mm thickness models and the 2 inner measurement points for 1.5-mm thickness models, the densities of contrast material affected the wall attenuations significantly (P < 0.0001). At the midportion for 1.5-mm thickness models, the wall attenuations were not affected by the densities of the contrast material (P = 0.6301), and were 65–68 HU. Conclusions:The effects of the intravascular density of contrast material, measurement point, and wall thickness should be considered in the attenuation measurement of the wall.

Serial Assessment of Liquefaction Necrosis of Mitral Annular Calcification by Echocardiography and Multislice Computed Tomography

An asymptomatic 54-year-old man, who had been on hemodialysis for 11 years because of chronic renal failure caused by chronic glomerulonephritis, was observed in our hospital. In November 2002, an aortic valve replacement was performed because of severe aortic stenosis. Preoperative echocardiography demonstrated mitral annular calcification (MAC) at the base of the posterior mitral annulus (Figure, A). Computed tomography of the heart also identified the MAC (Figure, B). In November 2004, follow-up echocardiography revealed enlargement of the MAC, which was detected as …

Development of new risk score for pre-test probability of obstructive coronary artery disease based on coronary CT angiography

Existing methods to calculate pre-test probability of obstructive coronary artery disease (CAD) have been established using selected high-risk patients who were referred to conventional coronary angiography. The purpose of this study is to develop and validate our new method for pre-test probability of obstructive CAD using patients who underwent coronary CT angiography (CTA), which could be applicable to a wider range of patient population. Using consecutive 4137 patients with suspected CAD who underwent coronary CTA at our institution, a multivariate logistic regression model including clinical factors as covariates calculated the pre-test probability (K-score) of obstructive CAD determined by coronary CTA. The K-score was compared with the Duke clinical score using the area under the curve (AUC) for the receiver-operating characteristic curve. External validation was performed by an independent sample of 319 patients. The final model included eight significant predictors: age, gender, coronary risk factor (hypertension, diabetes mellitus, dyslipidemia, smoking), history of cerebral infarction, and chest symptom. The AUC of the K-score was significantly greater than that of the Duke clinical score for both derivation (0.736 vs. 0.699) and validation (0.714 vs. 0.688) data sets. Among patients who underwent coronary CTA, newly developed K-score had better pre-test prediction ability of obstructive CAD compared to Duke clinical score in Japanese population.

Assessment of coronary stent in vitro on multislice computed tomography angiography: improved in-stent visibility by the use of 140-kV tube voltage.

Objective: To assess the effect of tube voltage on the in-stent visibility of coronary stents in vitro on computed tomography (CT) angiography. Methods: A total of 6 vascular models (3 models without stenosis and 3 with stenosis) using 3 kinds of stent (Bx Velocity, Express2, and Driver) with an inner diameter of approximately 3.5 mm and filled with contrast material (CT attenuation, 450 Hounsfield units) were scanned by means of a 16-detector row CT. We assessed the visual stenosis evaluation and inhomogeneity of stent lumen in 4 orientations (0-, 30-, 60-, and 90-degree angles) relative to the z-axis of the scanner using 3 imaging techniques (120-kV tube voltage using a medium convolution kernel, 120-kV tube voltage using a convolution kernel for bone, and 140-kV tube voltage using a convolution kernel for bone). Statistical analysis involved F test with a statistical significance of P < 0.05. Results: The convolution kernel for bone made it easier to evaluate the stenosis inside the stents, although it increased the luminal inhomogeneity significantly (Bx Velocity and Express2, P < 0.005; Driver, P < 0.05). The luminal inhomogeneity tended to increase as the strut diameter and the weight per unit length increased. Using 120-kV tube voltage, the luminal inhomogeneity inside the stents was at the minimum in the angle of 0 degree relative to the z-axis, and at the maximum in the angle of 90 degrees, except for Driver. The 140-kV tube voltage was effective for the improvement of luminal inhomogeneity and visibility of in-stent stenosis compared with the 120-kV tube voltage. Conclusions: The in-stent visibility of coronary stents on CT angiography can be improved by the use of 140-kV tube voltage with the convolution kernel for bone.

Coronary Artery Stent Evaluation Using a Vascular Model at 64-Detector Row CT: Comparison between Prospective and Retrospective ECG-Gated Axial Scans

Objective We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans. Materials and Methods As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen. Results The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error. Conclusion The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution.

Incidence, Predictors, and Midterm Clinical Outcomes of Myocardial Injury After Transcatheter Aortic-Valve Implantation

Our aim was to assess the clinical effects of myocardial injury after transcatheter aortic-valve implantation (TAVI). Between October 2013 and July 2016, 157 patients underwent TAVI with Sapien XT, Sapien 3, or CoreValve prostheses at our institute. Of these, 130 patients for whom the transapical approach was not used were included in this study. Myocardial injury was defined as a peak troponin I level of ≥1.5 ng/mL within 48 hours after TAVI. We evaluated the predictors of myocardial injury and compared the clinical outcomes of 82 patients classified as the myocardial injury group and 44 patients classified as the non-myocardial injury group. The patients were aged 85 ± 6 years. Myocardial injury occurred in 82 patients (65.1%). Age (per 1 increase) (odds ratio [OR]: 1.11, 95% confidence interval [CI]: 1.01-1.22, P = 0.041), female sex (OR: 3.88, 95% CI: 1.23-12.22, P = 0.021), valve type (Sapien XT; OR: 4.22, 95% CI: 1.15-15.47, P = 0.03, Core valve; OR: 18.12, 95% CI: 2.86-114.59, P = 0.002), balloon aortic valvuloplasty as a bridge therapy (OR: 0.10, 95% CI: 0.02-0.42, P = 0.002), and left ventricular end-diastolic volume (LVEDV) (per 1 increase) (OR: 0.97, 95% CI: 0.95-0.99, P = 0.003) were associated with myocardial injury in a multivariate model. The myocardial injury group did not have a higher rate of midterm (365-day) mortality (log-rank test P = 0.57) than the non-myocardial injury group on Kaplan-Meier analysis. Myocardial injury after TAVI was not associated with midterm mortality.

A case of prosthetic aortic valve endocarditis with massive vegetation underestimated by conventional two-dimensional transesophageal echocardiography: efficacy of three-dimensional transesophageal echocardiography.

A 71-year-old man who had undergone aortic valve replacement (AVR) twice due to infective endocarditis (IE) and a subsequent failed bioprosthetic valve (CarpentierEdwards PERIMOUNT Magna Ease 23-mm) was admitted to our hospital because of high fever for 2 weeks. Blood tests showed an elevated white blood cell (WBC) count (11.1 9 10/l) and C-reactive protein (CRP) level (20.8 mg/dl), without any remarkable findings upon physical examination. Aggregatibacter aphrophilus, one of the HACEK organisms, was identified in blood culture tests. Conventional two-dimensional (2D) transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) demonstrated no findings of prosthetic valve endocarditis (PVE) and malfunctions (Fig. 1a, b). High doses of multiple antibiotics were started intravenously due to suspected PVE. Even after 4 weeks, the high fever persisted, and the WBC count and CRP level remained elevated. There were no remarkable findings on repeat blood culture tests and the bedside 2D-TTE. A second 2D-TEE showed an unusual structural object attached to the tip of the valve leaflet, which was suspected as being vegetation (Fig. 1c). Thus, 3D-TEE images were acquired and analyzed, which revealed a vegetation mass attached to the valve leaflet. This resulted in the final diagnosis of PVE (Fig. 1d). Two weeks later, the patient’s third AVR was performed. In contrast to the intraoperative 2D-TEE findings, which were not substantially different from those of the second 2DTEE (Fig. 1e), the 3D-TTE images and operative findings showed massive vegetation (u15 mm) attached to the valve leaflet and covered by the stent, which is a blind spot in 2D-TEE (Fig. 1f, g, i). With antibiotic administration for another 2 weeks, the patient’s fever subsided and blood test results normalized. Thereafter, he was discharged without any other complaints. Compared to native valve IE, PVE is difficult to diagnose [1]. Although performing repeated TTE and TEE is useful in cases of suspected PVE, echocardiogram quality of the prosthetic valve leaflet, especially in an aortic position, still remains poor [1, 2]. Alternatively, the latest ESC guideline recommend the use of 18F-fluorodeoxyglucose positron emission tomography/computed tomography for diagnosing PVE [1, 3]; however, these procedures are not covered by the standard health care in Japan. Therefore, 3D-TEE may be useful in detecting vegetation, especially in Japan, since it allows 3D volume analysis of cardiac structures in any possible plane. This circumvents the vegetation blind spot that exists in 2D echocardiography, as shown in this case [4]. Electronic supplementary material The online version of this article (doi:10.1007/s12574-016-0311-7) contains supplementary material, which is available to authorized users.