On-Site Computed Tomography-Derived Fractional Flow Reserve Using a Machine-Learning Algorithm　- Clinical Effectiveness in a Retrospective Multicenter Cohort.

BACKGROUND: This study evaluated the diagnostic capability of on-site coronary computed tomography-derived computational fractional flow reserve (CT-FFR) determinations for detecting coronary artery disease (CAD), as assessed by invasive fractional flow reserve (FFR).Methods and Results:Seventy-four patients with coronary artery calcium scores <1,500 who underwent coronary CT angiography (CTA) and invasive FFR measurements within 90 days were retrospectively reviewed. CT-FFR was computed using a prototype machine-learning (ML) algorithm in 91 vessels; 47 vessels of 42 patients were determined to have significant CAD (FFR ≤0.8). Correlation between CT-FFR and FFR was good (r=0.786, P<0.001). Per-vessel area under the curve was significantly larger for CT-FFR (0.907, 95% confidence interval: 0.828-0.958) than for CTA stenosis ≥50% (0.595, 0.487-0.697) or ≥70% (0.603, 0.495-0.705) (both P<0.001). Standard coronary CTA classifications recommended further functional tests in 57 patients with moderate or worse stenosis on CTA. CT-FFR analysis (mean analysis time: 16.4±7.5 min) corrected the standard coronary CTA classification in 18 of 74 patients and confirmed it in 45 of 74 patients. Thus, the per-patient diagnostic accuracy of the classifications was improved from 66% (54-77%) to 85% (75-92%). CONCLUSIONS: On-site CT-FFR based on a ML algorithm can provide good diagnostic performance for detecting hemodynamically significant CAD, suggesting the high value of coronary CTA for selected patients in clinical practice.

Diagnostic accuracy of late iodine enhancement on cardiac computed tomography with a denoise filter for the evaluation of myocardial infarction.

We evaluated the image quality and diagnostic performance of late iodine enhancement (LIE) in dual-source computed tomography (DSCT) with low kilo-voltage peak (kVp) images and a denoise filter for the detection of acute myocardial infarction (AMI) in comparison with late gadolinium enhancement (LGE) magnetic resonance imaging (MRI). The Hospital Ethics Committee approved the study protocol. Before discharge, 19 patients who received percutaneous coronary intervention after AMI underwent DSCT and 1.5 T MRI. Immediately after coronary computed tomography (CT) angiography, contrast medium was administered at a slow injection rate. LIE-CT scans were acquired via dual-energy CT and reconstructed as 100-, 140-kVp, and mixed images. An iterative three-dimensional edge-preserved smoothing filter was applied to the 100-kVp images to obtain denoised 100-kVp images. The mixed, 140-kVp, 100-kVp, and denoised 100-kVp images were assessed using contrast-to-noise ratio (CNR), and their diagnostic performance in comparison with MRI and infarcted volumes were evaluated. Three hundred four segments of 19 patients were evaluated. Fifty-three segments showed LGE in MRI. The median CNR of the mixed, 140-, 100-kVp and denoised 100-kVp images was 3.49, 1.21, 3.57, and 6.08, respectively. The median CNR was significantly higher in the denoised 100-kVp images than in the other three images (P < 0.05). The denoised 100-kVp images showed the highest diagnostic accuracy and sensitivity. The percentage of myocardium in the four CT image types was significantly correlated with the respective MRI findings. The use of a denoise filter with a low-kVp image can improve CNR, sensitivity, and accuracy in LIE-CT.

Adenosine triphosphate stress dual-source computed tomography to identify myocardial ischemia: comparison with invasive coronary angiography.

PURPOSE: The purpose of this study was to investigate the utility incremental diagnostic value of combined assessment with coronary CT angiography (CCTA) and myocardial CT perfusion imaging (CTP) using dual-energy technology with an Adenosine Triphosphate (ATP) load technique. MATERIALS AND METHODS: Twenty-one patients underwent ATP-provocation dual-energy CT and CAG. We compared the diagnostic accuracy with CAG, for ischemic region due coronary stenosis by CCTA alone and CCTA combined with CTP (Combined CCTA/CTP). RESULTS: All of 21 patients CTP images could be evaluated, however 8 CCTA images could not be evaluated by calcification and motion artifact, so assessability was 61.9% (13/21) for CCTA alone, and 100% for Combined CCTA/CTP. With CAG results as a comparison, the sensitivity, specificity, positive predictive value, and negative predictive value were, respectively, 83.3% (20/24), 74.4% (29/39), 66.7% (20/30), and 87.8% (29/33) for CCTA alone, and 66.7% (16/24), 92.3% (36/39), 84.2% (16/19), and 81.8% (36/44) for combined CCTA/CTP. The diagnostic accuracy of the two methods were 77.8% (49/63) and 82.5% (52/63). CONCLUSION: Dual-energy CT may be a useful modality for perfusion assessment and correlated well with the severity of stenosis on CAG. This technique may even be of use in cases of severe calcification in the coronary artery wall.

Bare metal stent implantation for in-stent restenosis with a drug-eluting stent.

Following the positioning of a bare metal stent (BMS) implant, a yellow plaque is healed with a reduction of the color grade and thrombogenicity, i.e. vulnerability by angioscopy in the chronic phase ("plaque sealing" of BMS; the "whitening effect" of BMS). However, we have reported that thrombus and yellow plaque increases at the drug-eluting stent (DES) site. A 71-year-old man underwent percutaneous coronary intervention using two DESs for a severe stenotic lesion in his right coronary artery. Follow-up coronary angiography (CAG) showed in-stent restenosis (ISR) at the stent-overlap site. We performed traditional balloon angioplasty, but follow-up CAG showed ISR again at the same position as the first restenosis. In angioscopic findings, the normal vessel wall was white, but the site of DES implantation was yellow and a yellow, soft, swelling neointimal proliferation-like vulnerable plaque was observed at the restenotic site. In expectation of the "whitening effect" of BMS, we implanted a new BMS. As anticipated, follow-up CAG showed no restenosis. Moreover, the angioscopic findings indicated a clean, white, neointimal proliferation-like stable plaque at the BMS implant site in the yellow vulnerable area of DES. The "BMS in DES" therapy should be considered one of the strategies for ISR of DES.

Myocardial ischemia in acute coronary syndrome: assessment using 64-MDCT.

OBJECTIVE: We investigated the performance of 64-MDCT myocardial imaging in assessing myocardial ischemia in acute coronary syndrome (ACS). MATERIALS AND METHODS: Cardiac CT was performed in 35 patients with ACS: 24 patients with acute myocardial infarction (AMI) and 11 patients with unstable angina pectoris (UAP). We reconstructed 2D myocardial images at diastolic and systolic phases using the same raw data as those used for coronary CT angiography. The CT number in the myocardium was used as an estimate of ischemia. The myocardium was shown using a color scale that depicts faint low-density areas more clearly than gray scale. We evaluated the variations in myocardial enhancement during the cardiac cycle in the territory of the culprit lesion. In addition, we classified patients on the basis of the transmurality of myocardial enhancement and examined whether this feature correlates with myocardial damage. RESULTS: Myocardial imaging at systole showed myocardial hypoenhancement in territories of the culprit lesion in 91% of patients with ACS, 96% of patients with AMI, and 75% of patients with UAP. The hypoenhancement areas at systole tended to be more extensive than those at diastole. The transmural extent of hypoenhancement at systole correlated with myocardial damage, which was shown by myocardial biomarkers. CONCLUSION: CT myocardial imaging can be used to assess myocardial ischemia in the appropriate region of ACS with high sensitivity.

A case of a newly developed yellow neointima at stent implanted site 1 year after sirolimus-eluting stent placement: angioscopic findings.

Coronary angioscopy is a useful tool for understanding plaque characteristics through the plaque color and surface thrombus formation. We experienced an interesting case of a newly developed yellow neointima 400 days after a sirolimus-eluting stent implantation. A 72-year-old woman suffering from angina pectoris was admitted to our hospital. Coronary angiography revealed severe stenosis at the proximal left descending artery and she was implanted with a sirolimus-eluting stent. Coronary angioscopic observation immediately after stent implantation revealed the presence of yellow plaque only at the most severe stenosis lesion in the stent placement site. We performed a coronary angiography 400 days after the sirolimus-eluting stent implantation and did not find an in-stent restenosis. An intravascular ultrasound indicated minimum neointimal formation. By coronary angioscopy, we could clearly observe that the neointima had covered the surface of the stent struts; the stent struts were barely visible under the neointima. Surprisingly, neointima formed in response to the sirolimus-eluting stent was entirely yellow. Precise mechanisms of producing yellow neointima was unknown, we may observe a pathologic neointima induced by sirolimus-eluting stent.

Detection of myocardial ischemia using 64-slice MDCT.

BACKGROUND: The purpose is to investigate the ability of 64-slice multidetector computed tomography (MDCT) at rest in detecting myocardial ischemia, conventionally depicted by myocardial perfusion scintigraphy (MPS). METHODS AND RESULTS: In 75 patients with suspected coronary artery disease, cardiac CE-MDCT at rest and stress/rest MPS were performed. The 2D myocardial images were reconstructed in diastolic and systolic phases using raw data from coronary computed tomography (CT) angiography. CT numbers in the myocardium were used as an estimate of myocardial enhancement. The myocardium was shown using a color scale that depicts faint low-density areas more clearly than gray scale. The variation in myocardial enhancement was evaluated at systole and diastole for those segments depicted as ischemia on MPS. A pattern of transient endocardial hypo-enhancement at systole and normal enhancement at diastole as the ischemic pattern on CT myocardial image was defined. MPS diagnosed myocardial ischemia in 40 of 75 patients. Use of the ischemic pattern on CT images distinguished patients with and without ischemia with a sensitivity of 90%, specificity of 83%, positive predictive value of 86% and negative predictive value of 88%. CONCLUSIONS: CT myocardial imaging at rest demonstrates a characteristic enhancement pattern for ischemia. This has potential as a non-invasive method for detecting ischemia.