Relationship between coronary high-intensity plaques on T1-weighted imaging by cardiovascular magnetic resonance and vulnerable plaque features by near-infrared spectroscopy and intravascular ultrasound: a prospective cohort study.

BACKGROUND: This study aimed to compare the coronary plaque characterization by cardiovascular magnetic resonance (CMR) and near-infrared spectroscopy (NIRS)-intravascular ultrasound (IVUS) (NIRS-IVUS), and to determine whether pre-percutaneous coronary intervention (PCI) evaluation using CMR identifies high-intensity plaques (HIPs) at risk of peri-procedural myocardial infarction (pMI). Although there is little evidence in comparison with NIRS-IVUS findings, which have recently been shown to identify vulnerable plaques, we inferred that CMR-derived HIPs would be associated with vulnerable plaque features identified on NIRS-IVUS. METHODS: 52 patients with stable coronary artery disease who underwent CMR with non-contrast T1-weighted imaging and PCI using NIRS-IVUS were studied. HIP was defined as a signal intensity of the coronary plaque-to-myocardial signal intensity ratio (PMR) ≥ 1.4, which was measured from the data of CMR images. We evaluated whether HIPs were associated with the NIRS-derived maximum 4-mm lipid-core burden index (maxLCBI4mm) and plaque morphology on IVUS, and assessed the incidence and predictor of pMI defined by the current Universal Definition using high-sensitive cardiac troponin-T. RESULTS: Of 62 lesions, HIPs were observed in 30 lesions (48%). The HIP group had a significantly higher remodeling index, plaque burden, and proportion of echo-lucent plaque and maxLCBI4mm ≥ 400 (known as large lipid-rich plaque [LRP]) than the non-HIP group. The correlation between the maxLCBI4mm and PMR was significantly positive (r = 0.51). In multivariable logistic regression analysis for prediction of HIP, NIRS-derived large LRP (odds ratio [OR] = 5.41; 95% confidence intervals [CIs] 1.65-17.8, p = 0.005) and IVUS-derived echo-lucent plaque (OR = 5.12; 95% CIs 1.11-23.6, p = 0.036) were strong independent predictors. Furthermore, pMI occurred in 14 of 30 lesions (47%) with HIP, compared to only 5 of 32 lesions (16%) without HIP (p = 0.005). In multivariable logistic regression analysis for prediction of incidence of pMI, CMR-derived HIP (OR = 5.68; 95% CIs 1.53-21.1, p = 0.009) was a strong independent predictor, but not NIRS-derived large LRP and IVUS-derived echo-lucent plaque. CONCLUSIONS: There is an important relationship between CMR-derived HIP and NIRS-derived large LRP. We also confirmed that non-contrast T1-weighted CMR imaging is useful for characterization of vulnerable plaque features as well as for pre-PCI risk stratification. Trial registration The ethics committee of Juntendo Clinical Research and Trial Center approved this study on January 26, 2021 (Reference Number 20-313).

Dual-energy CT imaging of atherosclerotic plaque using novel ultrasmall superparamagnetic iron oxide in hyperlipidemic rabbits.

BACKGROUND: A study using magnetic resonance imaging (MRI) revealed that ultra-small superparamagnetic iron oxide is phagocytosed by macrophages. However, MRI has limitations in obtaining clear images due to its poor spatial and temporal resolutions. PURPOSE: To examine whether the use of dual-energy computed tomography (DECT) facilitated the visualization of carboxymethyl-diethylaminoethyl dextran magnetite ultra-small superparamagnetic iron oxide (CMEADM-U) accumulation in arteriosclerotic lesions using hyperlipidemic rabbits. MATERIAL AND METHODS: CMEADM-U at 0.5 mmol Fe/kg was administered to Watanabe hereditary atherosclerotic (WHHL) rabbits (n = 6, 24 sections) and New Zealand white (NZW) rabbits (n = 2, 6 sections). After 72 h, DECT was performed to prepare virtual monochromatic images (35 keV, 70 keV) and an iron-based map. Subsequently, the aorta was collected along with hematoxylin and eosin staining, Berlin blue (BB) staining, and RAM11 immunostaining. RESULTS: In the WHHL rabbits, CMEADM-U accumulation was not observed at 70 keV. However, CMEADM-U accumulation consistent with an arteriosclerotic lesion was observed at 35 keV and the iron-based map. On the other hand, in the NZW rabbits, there was no accumulation of CMEADM-U in any images. Further, there were significant differences in the iron-based map value at the site of accumulation among the grades of expression on BB staining and RAM11 immunostaining. In addition, there was a good correlation at 35 kev and iron-based map value (r = 0.42; P < 0.05). CONCLUSION: DECT imaging for CMEADM-U facilitated the assessment of macrophage accumulation in atherosclerotic lesions in an in vivo study using a rabbit model of induced aortic atherosclerosis.

Clinical significance of 123I-BMIPP washout rate in patients with uncertain chronic heart failure.

BACKGROUND: Recently, triglyceride deposit cardiomyovasculopathy (TGCV) with defective intracellular lipolysis was found to be a disease that causes heart failure. As a diagnostic criterion for TGCV, an Iodaine-123-ß-methyl iodophenyl-pentadecanoic acid washout rate (BMIPP WOR) of < 10% is used, but its clinical significance in patients with heart failure remains to be clarified. METHODS: In 62 hospitalized patients with chronic heart failure, 123I-BMIPP myocardial single-photon emission computed tomography (SPECT) was performed predischarge state. The prevalence of TGCV was investigated. Subsequently, follow-up was conducted for ≥ 90 days (mean: 724.6 ± 392.7 days), and the association between the BMIPP WOR and cardiac events was examined, establishing all-cause mortality and admission due to heart failure as endpoints. RESULTS: Of the 62 patients, the WOR was < 10% in 41 (66.1%). Of these, 26 (41.9%) were diagnosed with definite TGCV. Furthermore, cardiac events were noted in 12 patients (19.4%). Analysis with Cox proportional hazards models showed that the BMIPP WOR < 4.5% was a significant event-predicting factor [HR 4.29, 95% CI: 1.20-16.87; p = 0.0245]. On a Kaplan-Meier curve, the WOR was 4.5%; there was a significant difference in the incidence of events (p = 0.0298). CONCLUSION: In the predischarge state of heart failure, 123I-BMIPP myocardial SPECT was performed. In approximately 40% of the patients, a diagnosis of TGCV was made. The results suggested that the BMIPP WOR is useful for predicting the prognosis of chronic heart failure patients regardless of TGCV.

Coronary flow disturbance assessed by vorticity as a cause of functionally significant stenosis.

OBJECTIVES: Vorticity calculated using computational fluid dynamics (CFD) could assess the flow disturbance generated by coronary stenosis. The purpose of this study was to investigate whether vorticity would be an underlying cause of functionally significant stenosis assessed by invasive fractional flow reserve (FFR). METHODS: This retrospective study included 113 patients who underwent coronary CT angiography showing intermediate stenosis and subsequent invasive FFR between December 2015 and March 2020. Vorticity at the stenosis site was calculated using a mesh-free CFD method. We also evaluated the minimum lumen area (MLA) and diameter stenosis (DS) of the lesion. Invasive FFR of ≤ 0.80 was considered functionally significant. Data were compared using Student's t-test and logistic regression analysis was performed. RESULTS: Of the evaluated 144 vessels, 53 vessels (37%) showed FFR ≤ 0.80. Vorticity of significant stenosis was significantly higher than non-significant stenosis (569 ± 78 vs. 328 ± 34 s-1, p < 0.001). A significant negative relationship was present between vorticity and invasive FFR (R2 = 0.31, p < 0.001). Multivariate logistic regression analysis including MLA and DS showed that vorticity (per 100 s-1, odds ratio: 1.36, 95% confidence interval: 1.21-1.57, p < 0.001) was a statistically significant factor to detect functional significance. The area under the receiver operating characteristic curve statistically significantly increased when vorticity was combined with DS and MLA (0.76 vs. 0.87, p = 0.001). CONCLUSIONS: Vorticity had a statistically significant negative relationship with invasive FFR independent of geometric stenosis. KEY POINTS: • Flow disturbance caused by coronary stenosis could be evaluated by calculating vorticity which is defined as the norm of the rotation of the velocity vector. • Vorticity was statistically significantly higher in stenosis with functional significance than stenosis without. • Vorticity has an additive value to detect functionally significant stenosis over geometrical stenosis.

Plaque characteristics on coronary CT angiography associated with the positive findings of fractional flow reserve and instantaneous wave-free ratio.

BACKGROUND: Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are useful in determining indications for revascularization of coronary artery disease (CAD). Although the discordance of FFR and iFR was noted in approximately 20%, this cause has not been well established. We investigated patient background and features on coronary CT angiography (CCTA) showing not only FFR- and iFR-positive findings but also discordance between FFR ≤ 0.8 and iFR ≤ 0.89. METHODS: Subjects were consecutively treated in 83 cases with 105 vessels in which stenosis of 30-90% was detected at one vessel of at least 2 mm or more in the major epicardial vessels and FFR and iFR was performed within subsequent 90 days, among suspected CAD which underwent CCTA. The factors affecting not only FFR- and iFR-positive findings, respectively, but also discordance between FFR and iFR was evaluated using logistic regression analysis on per-patient and per-vessel basis. RESULTS: FFR- and iFR-positive findings were observed in 42 vessels (40.0%) and 34 vessels (32.3%), respectively. Discordance between FFR ≤ 0.8 and iFR ≤ 0.89 was observed in 22 vessels (21.0%) of 21 patients. In multivariate logistic analysis, LAD (OR 3.55; 95%CI 1.20-11.71; p = 0.0217) and lumen volume/myocardial weight (L/M) ratio (OR 0.93; 0.86-0.99, p = 0.0290) were significant predictors for FFR-positive findings. For iFR-positive findings, LAD (OR 3.86; 95%CI 1.12-13.31; p = 0.0236) was only significant predictor. In FFR ≤ 0.8 and iFR > 0.89 group (15 vessels, 14.3%), positive remodeling (PR) (OR 5.03, 95%CI 1.23-20.48, p = 0.0205) was significant predictor. In FFR > 0.8 and iFR ≤ 0.89 group (7 vessels, 6.7%), there were no significant predictors. CONCLUSION: On CCTA characteristics, a relevant predictor for FFR-positive findings included low L/M ratio. PR was significant predictor in FFR-positive, iFR-negative patients among those with discordance between the FFR and iFR.

Adjustment of CT-fractional flow reserve based on fluid-structure interaction underestimation to minimize 1-year cardiac events.

The purpose of the study was to evaluate the optimal cut-off value of CT-Fractional Flow Reserve (CT-FFR) using fluid-structure interaction and how to adjust the CT-FFR's underestimation from a standpoint of minimize 1-year cardiac events. Subjects were 38 cases with 44 vessels in which stenosis of 30-90% was detected using one-rotation scanning by 320-row coronary CT angiography (CCTA) and invasive FFR (i-FFR) was performed within subsequent 90 days. CT-FFR was calculated using on-site from the multiple cardiac phases. A hypothetical 1-year cardiac event incidence was estimated using previous evidences when revascularization was decided based on CT-FFR. We assessed the optimal cut-off value of CT-FFR and how to correct the CT-FFR to minimize hypothetical cardiac events under four different disease prevalence (20%, 25%, 30%, 35%, and 40%). A total of 16 vessels had i-FFR ≤ 0.8. On per-patient basis, the sensitivity, specificity, positive predict value, negative predict value, and diagnostic accuracy of CT-FFR â‰¦ 0.8 vs CCTA > 50% to detect functional stenosis defined as invasive FFR â‰¦ 0.80 were 93.3% vs 73.3%, 73.9% vs 26.1%, 70.0% vs 39.3%, 94.4% vs 60.0%, and 81.6% vs 44.7%, respectively. For minimize 1-year cardiac events, the optimal cut-off value for more than 30% of disease prevalence was 0.80. However, the optimal cut-off value for 20, 25, and 30% was 0.54 in any cases. After the adjustment of CT-FFR using a formula of 0.3X + 0.634 for CT-FFR < 0.7 to counteract its underestimation, the % reduction of the events for 20, 25, 30, 35, and 40% at a 0.80 cut-off were 19.0%, 15.6%, 12.6%, 10.0%, and 7.7% respectively. It was reasonable to support that the optimal cut-off value was 0.80 in disease prevalence of more than 30% for minimize 1-year cardiac events. However, underestimation should be adjusted to reduce cardiac events, especially when disease prevalence is low.

Chest X-Ray Revealed a Slowly Progressive Giant Right Coronary Artery Aneurysm in an Asymptomatic Patient.

A giant right coronary artery aneurysm (60 × 70 mm in size) was incidentally found by chest X-ray as an abnormal right atrial enlargement, and it needed surgical resection. Although the majority of giant coronary artery aneurysms present with symptoms of coronary ischemia, this case presented without any specific symptom. This study indicates that when chest X-ray shows abnormal atrial enlargement, a differential diagnosis of giant coronary artery aneurysm may need to be considered.

Noninvasive Computed Tomography-Derived Fractional Flow Reserve Based on Structural and Fluid Analysis: Reproducibility of On-site Determination by Unexperienced Observers.

OBJECTIVE: The aim of this study was to evaluate the reproducibility of computed tomography (CT)-derived fractional flow reserve (FFR) determined on site by inexperienced observers using a postprocessing software based on structural and fluid analysis. METHODS: Using 21 coronary vessels in 7 patients who underwent 320-row coronary CT angiography and catheter-FFR, 2 independent inexperienced observers (A: a student radiation technologist; B: a nonmedical staff) determined the CT-FFR using a postprocessing software. After a 20-minute training session, both observers postprocessed all vessels and readjusted their settings after another training/feedback. These CT-FFRs were compared with values determined by an expert analyst. RESULTS: The mean processing times were 23 ± 4 minutes (automatic), 71 ± 5 minutes (observer A), and 57 ± 7 minutes (observer B) per patient. The initial correlations with expert data were r = 0.92 (observer A) and 0.73 (observer B) and increased to 0.83 for observer B after additional training. The final absolute difference with the expert data was 0.000 to 0.020. The correlation between catheter-FFR and expert CT-FFR was r = 0.76. CONCLUSIONS: The CT-derived FFR on-site postprocessing software showed good reproducibility for measurements by inexperienced observers.

Clinical significance of transluminal attenuation gradient in 320-row area detector coronary CT angiography.

The clinical significance of the transluminal attenuation gradient (TAG) has not been established. We evaluated the incremental diagnostic value of TAG by 320-row area detector computed tomography (320-ADCT). Subjects were 65 patients who underwent one-rotation scanning by 320-ADCT and invasive coronary angiography (ICA) within 3 months. TAG values were obtained for the major epicardial vessels 2 mm or more each in RCA, LAD and LCX using automatic analysis software. Moreover, TAG values that excluded calcified lesions in calculation of the regression line were also evaluated (excluded-TAG). In LAD, 21 intermediate lesions underwent functional flow reserve (FFR), and the incremental diagnostic value for functional stenosis was evaluated. The TAG values in the normal vessels were - 8.3 ± 5.0 (HU/cm) for the RCA (n = 32), - 23.3 ± 4.3 for the LAD (n = 9) and - 20.6 ± 10.0 for the LCX (n = 32). The RCA value was significantly higher (p < 0.001). The TAG values with stenosis degrees of ≤ 25%, 26-75%, ≥ 76% on ICA were - 8.3 ± 5.0 (n = 32) vs - 10.3 ± 7.2 (n = 25) vs - 10.0 ± 5.4 (n = 4) in the RCA, - 23.3 ± 4.3 (n = 9) vs - 21.0 ± 11.5 (n = 35) vs - 23.5 ± 15.3 (n = 10) in the LAD and - 21.1 ± 15.1 (n = 32) vs - 21.1 ± 15.1 (n = 16) vs - 17.7 ± 15.7 (n = 6) in the LCX, with no significant difference among the three groups. The excluded-TAG values also showed no significant difference. The area under the curve in the diagnosis of FFR < 0.8 in 21 LAD cases was 0.542 for CT only, 0.694 for CT + TAG, and 0.694 for CT + excluded-TAG. In single time-phase scanning by 320-ADCT, TAG does not offer an incremental diagnostic value.

Myocardial triglyceride content in patients with left ventricular hypertrophy: comparison between hypertensive heart disease and hypertrophic cardiomyopathy.

Proton magnetic resonance spectroscopy (1H-MRS) enables the assessment of myocardial triglyceride (TG) content, which is reported to be associated with cardiac dysfunction and morphology accompanied by metabolic disorder and cardiac hemodynamic status. The clinical usefulness of myocardial TG content measurements in patients with left ventricular hypertrophy (LVH) has not been fully investigated. We examined whether myocardial TG content assessed by 1H-MRS was useful for diagnosis in patients with LVH. To quantify myocardial TG content, we conducted 1H-MRS in 35 subjects with LVH. Left ventricular function was measured by cardiac magnetic resonance imaging. Patients were assigned to a hypertensive heart disease (HHD, n = 10) or hypertrophic cardiomyopathy (HCM, n = 25) group based on the histology and/or late gadolinium enhancement pattern. The myocardial TG content was significantly higher in the HHD group than in the HCM group (2.14 ± 1.29 vs. 1.09 ± 0.72 %, P < 0.001). Myocardial TG content were significantly and negatively correlated with LV mass (r = -0.41, P < 0.04) and stroke volume (r = -0.64, P < 0.05) in the HCM group and HHD group, respectively. In a multivariate analysis, LV mass volume and diagnosis of HCM or HHD were independent factors of the myocardial TG content. The results suggest that myocardial metabolism may differ between HCM and HHD patients and that measurement of myocardial TG content by 1H-MRS may be useful for evaluating the myocardial metabolic features of LVH.

[The Effect of Reconstruction Method on the Ability to Analyze of FFR Using CT].

BACKGROUND: Invasive-fractional flow reserve (FFR) is the reference standard to evaluate functional ischemia of coronary arteries, and is used to decide if percutaneous transluminal coronary angioplasty is necessary. Recently, computed tomography-derived FFR (CT-FFR) is emerged as an alternative non-invasive method. OBJECTIVES: To evaluate the effect of reconstruction methods and image parameters on the accuracy of CT-FFR calculation. METHODS: A total of 26 segments in the consecutive 10 coronary CT angiography (CCTA) studies were evaluated. All studies were reconstructed using three different techniques: 1) filtered back projection (FBP), 2) adaptive iterative dose reduction 3D (AIDR 3D), and 3) forward projected model-based iterative reconstruction solution (FIRST). Vessel segmentation was performed automatically by CT-FFR software, with manual adjustment if necessary. Calculated CT-FFR was compared with the invasive FFR data. RESULTS: Compared to FBP, AIDR 3D and FIRST resulted in more successful automatic segmentation. When using FIRST, 7 segments (27%) were completed without manual adjustment. These segments had relatively larger vessel diameter, higher CT number, and lower noise. The difference between the calculated CT-FFR and invasive-FFR was 0.02±0.01. Among the remaining, 10 segments (38%) required manual adjustments of centerline, 7 segments (27%) required manual adjustments of contour, and 2 segments (8%) did not reach to the CT-FFR calculation. CONCLUSION: AIDR 3D and FIRST were useful for reliable automatic segmentation and analysis of CT-FFR.

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.

Practice recommendation for measuring washout rates in 123I-BMIPP fatty acid images.

The purpose of this practice recommendation is to specifically identify the critical steps involved in performing and interpreting 123I-ß-methyl-iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) and measurement of washout rate (WR) from the heart. This document will cover backgrounds, patient preparation, testing procedure, visual image interpretation, quantitation methods using planar and SPECT studies, and reporting of WR. The pitfall and some tips for the calculation of 123I-BMIPP WR are also included. The targets of global and regional WR calculation include ischemic heart disease, cardiomyopathy, heart failure, and triglyceride deposit cardiomyovasculopathy, an emerging rare heart disease.

Additional prognostic impact of plaque characterization with on-site CT-derived fractional flow Reserve in Coronary CT angiography.

BACKGROUND: On-site computed tomography-derived fractional flow reserve (CT-FFR) is a feasible method for examining lesion-specific ischemia, and plaque analysis of coronary CT angiography (CCTA) is useful for predicting future cardiac events. However, their utility and association on a per-vessel level remain unclear. METHODS: We analyzed vessels showing 50-90 % stenosis on CCTA where planned revascularization was not performed after CCTA within 90 days. Relevant features, including CT-FFR and the plaque burden [necrotic core to the total plaque volume (% necrotic core), and non-calcified plaque (NCP) to vessel volume (% NCP)] using a novel algorithm for analyzing plaque to predict vessel-oriented composite outcomes (VOCO), including cardiac death, non-fatal myocardial infarction, and unplanned vessel-related revascularization, were assessed. RESULTS: In 256 patients (68.7 ±â€¯9.4 years; 73.8 % male) with 354 vessels (10.5 % CT-FFR ≤0.80), VOCO occurred in 24 vessels (6.8 %) during a median follow-up of 3.6 years. Multivariable Cox analysis revealed CT-FFR ≤0.80 had the pronounced impact on VOCO, and moreover, higher % necrotic core and % NCP were independently associated with VOCO [adjusted hazard ratio 3.43 (95 % confidence interval 1.42-8.29) and 4.05 (1.19-13.71), respectively], especially for vessels with CT-FFR >0.80. CONCLUSIONS: In vessels without planned revascularization, per-vessel CT-FFR ≤0.80 was the notable predictor of future cardiac events. Additionally, necrotic core volume and NCP were identified as independent predictors along with CT-FFR.

Image quality and radiation dose stratified by patient heart rate for coronary 64- and 320-MDCT angiography.

OBJECTIVE. The purpose of this study is to retrospectively measure and compare estimated radiation doses between consecutive patient cohorts who underwent coronary imaging CT with 64- and 320-MDCT scanners. MATERIALS AND METHODS. Subjects without arrhythmia (n = 4475) underwent imaging with 64-MDCT (n = 770) and 320-MDCT (n = 3705) scanners and were classified into one of five subgroups according to the patient heart rate and the image acquisition strategy. For all patients, image quality was subjectively evaluated using a 3-point scale. Estimated radiation dose and image quality were compared between subjects stratified by CT scanner and by subgroups imaged with each technology. RESULTS. For patients with a heart rate of 60 beats/min or less, the estimated radiation dose was halved (3.8 ± 2.0 vs 7.6 ± 2.6 mSv) when the 320-MDCT scanner (n = 2787) replaced the 64-MDCT scanner (n = 511). For the entire cohort, image quality score was significantly better (2.9 ± 0.4 vs 2.8 ± 0.5; p < 0.0001) and the effective dose was significantly lower (4.9 ± 3.3 vs 9.9 ± 5.4 mSv; p < 0.0001) for 320-MDCT scanners, compared with 64-MDCT scanners. CONCLUSION. Wide area-detector coronary CT angiography protocols have reduced radiation dose, with image quality maintained at the same level, compared with 64-MDCT technologies.

Prospective ECG-gated coronary 320-MDCT angiography with absolute acquisition delay strategy for patients with persistent atrial fibrillation.

OBJECTIVE: The purpose of this study was to evaluate image quality and radiation dose when patients with atrial fibrillation undergo coronary CT angiography (CTA) using prospectively ECG-gated 320-MDCT technology with an absolute-delay strategy. MATERIALS AND METHODS: A cohort of 75 consecutive patients (60 men and 15 women; age (± SD), 71 ± 10 years) who underwent prospectively ECG-gated coronary CTA using a 320-MDCT scanner during atrial fibrillation was matched with 75 control patients imaged in sinus rhythm. All coronary CTA for the atrial fibrillation cohort used absolute-delay strategy. Subjective image quality score and the dose-length product (DLP) were compared between the two cohorts and, for the atrial fibrillation cohort, among those patients imaged over a different number of heartbeats. The accuracy of stenosis detection was evaluated in 17 studies of the atrial fibrillation cohort using catheter angiography as a reference standard. RESULTS: For those patients imaged in atrial fibrillation, one- and two-beat acquisitions were performed in 26.7% (n = 20) and 40% (n = 30) of patients, respectively. There was no significant difference in image quality between the atrial fibrillation (2.9 ± 0.4) and sinus rhythm (2.9 ± 0.3) cohorts, nor was there a difference in image quality with respect to the number of heartbeats used in the acquisition. The atrial fibrillation cohort had an 80% higher DLP (680 ± 470 vs 372 ± 236 mGy × cm, p < 0.0001). The patient-based sensitivity and negative predictive value for stenosis detection were both 100%. CONCLUSION: Using an absolute-delay strategy, two thirds of patients who underwent prospectively ECG-gated coronary CTA using a 320-MDCT scanner were imaged within two heartbeats or fewer. Compared with patients imaged in sinus rhythm, the image quality was comparative and the radiation dose was 1.8-fold higher.

[Prospective electrocardiogram gated coronary 320-row area detector computed tomography angiography using low tube current scanning with full reconstruction].

BACKGROUND: It is possible to obtain equivalent image quality and a lower radiation dose using low tube current scanning with full reconstruction as compared to usual tube current scanning with half reconstruction in a 320-row area detector computed tomography (ADCT) angiography. METHOD: Of 589 patient underwent coronary CT angiography (CCTA), 11 patients with (RR-PQ) ≥1069 ms were enrolled. In those patients, low tube current (50% mA) scanning with full or half reconstruction were performed. As a control, 11 patients with matched pairs of tube voltage, BMI and heart rate who underwent usual scanning with half reconstruction (100% mA with half reconstruction) were selected. Standard deviation of the CT value (SD) was measured in aorta (Ao), left atrium (LA) and left ventricle (LV), and extended dose-length products (DLP.e) were calculated. RESULT: Significant motion artifact was not observed in any patients. SD of 50% mA with half reconstruction, 50% mA with full reconstruction, and 100% mA with half reconstruction were 28.1±2.6, 20.3±1.9, 20.7±2.5 HU in Ao, 34.4±4.4, 24.9±2.8, 24.9±3.1 HU in LA, and 29.7±2.3, 21.7±1.9, 22.1±2.3 HU in LV, respectively. There were not significant differences between 50% mA with full reconstruction and 100% mA with half reconstruction, but there were significant differences between 50% mA with half reconstruction and 50% mA with full reconstruction in all sites. The DLP.e of 50% mA scanning (74.1±21.8 mGy·cm) was significantly lower than 100% mA scanning (161.9±28.9 mGy·cm). CONCLUSION: CCTA with lower radiation dose and equivalent image quality can be obtained by ADCT using 50% mA scanning with full reconstruction in patients with (RR-PQ) ≥1069 ms.

Practice Recommendation for Measuring Washout Rates in 123I-BMIPP Fatty Acid Images.

The purpose of this practice recommendation is to specifically identify the critical steps involved in performing and interpreting 123I-ß-methyl-iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) and measurement of washout rate (WR) from the heart. This document will cover backgrounds, patient preparation, testing procedure, visual image interpretation, quantitation methods using planar and SPECT studies, and reporting of WR. The pitfall and some tips for the calculation of 123I-BMIPP WR are also included. The targets of global and regional WR calculation include ischemic heart disease, cardiomyopathy, heart failure, and triglyceride deposit cardiomyovasculopathy, an emerging rare heart disease.

Impact of a Deep Learning-based Super-resolution Image Reconstruction Technique on High-contrast Computed Tomography: A Phantom Study.

RATIONALE AND OBJECTIVES: Deep-learning-based super-resolution image reconstruction (DLSRR) is a novel image reconstruction technique that is expected to contribute to improvement in spatial resolution as well as noise reduction through learning from high-resolution computed tomography (CT). This study aims to evaluate image quality obtained with DLSRR and assess its clinical potential. MATERIALS AND METHODS: CT images of a Mercury CT 4.0 phantom were obtained using a 320-row multi-detector scanner at tube currents of 100, 200, and 300 mA. Image data were reconstructed by filtered back projection (FBP), hybrid iterative reconstruction (HIR), model-based iterative reconstruction (MBIR), deep-learning-based image reconstruction (DLR), and DLSRR at image reconstruction strength levels of mild, standard, and strong. Noise power spectrum (NPS), task transfer function (TTF), and detectability index were calculated. RESULTS: The magnitude of the noise-reducing effect in comparison with FBP was in the order MBIR

Fully automated coronary artery calcium quantification on electrocardiogram-gated non-contrast cardiac computed tomography using deep-learning with novel Heart-labelling method.

Aims: To develop an artificial intelligence (AI)-model which enables fully automated accurate quantification of coronary artery calcium (CAC), using deep learning (DL) on electrocardiogram (ECG)-gated non-contrast cardiac computed tomography (gated CCT) images. Methods and results: Retrospectively, 560 gated CCT images (including 60 synthetic images) performed at our institution were used to train AI-model, which can automatically divide heart region into five areas belonging to left main (LM), left anterior descending (LAD), circumflex (LCX), right coronary artery (RCA), and another. Total and vessel-specific CAC score (CACS) in each scan were manually evaluated. AI-model was trained with novel Heart-labelling method via DL according to the manual-derived results. Then, another 409 gated CCT images obtained in our institution were used for model validation. The performance of present AI-model was tested using another external cohort of 400 gated CCT images of Stanford Center for Artificial Intelligence of Medical Imaging by comparing with the ground truth. The overall accuracy of the AI-model for total CACS classification was excellent with Cohen's kappa of k = 0.89 and 0.95 (validation and test, respectively), which surpasses previous research of k = 0.89. Bland-Altman analysis showed little difference in individual total and vessel-specific CACS between AI-derived CACS and ground truth in test cohort (mean difference [95% confidence interval] were 1.5 [-42.6, 45.6], -1.5 [-100.5, 97.5], 6.6 [-60.2, 73.5], 0.96 [-59.2, 61.1], and 7.6 [-134.1, 149.2] for LM, LAD, LCX, RCA, and total CACS, respectively). Conclusion: Present Heart-labelling method provides a further improvement in fully automated, total, and vessel-specific CAC quantification on gated CCT.