Evaluation of coronary artery lumen diameter with 16-slice multidetector-row computed tomography

Image reconstruction for endoscopic photoacoustic tomography including effects of detector responses

In photoacoustic tomography (PAT), conventional image reconstruction methods are generally based on the assumption of an ideal point-like ultrasonic detector. This assumption is appropriate when the receiving surface of the detector is sufficiently small and/or the distance between the imaged object and the detector is large enough. However, it does not hold in endoscopic applications of PAT. In this study, we propose a model-based image reconstruction method for endoscopic photoacoustic tomography (EPAT), considering the effect of detector responses on image quality. We construct a forward model to physically describe the imaging process of EPAT, including the generation of the initial pressure due to optical absorption and thermoelastic expansion, the propagation of photoacoustic waves in tissues, and the acoustic measurement. The model outputs the theoretical sampling voltage signal, which is the response of the ultrasonic detector to the acoustic pressure reaching its receiving surface. The images representing the distribution map of the optical absorption energy density on cross-sections of the imaged luminal structures are reconstructed from the sampling voltage signals output by the detector through iterative inversion of the forward model. Compared with the conventional approaches based on back-projection and other imaging models, our method improved the quality and spatial resolution of the resulting images.

Accuracy of ultra-high-resolution computed tomography with a 0.3-mm detector for quantitative assessment of coronary artery stenosis grading in comparison with conventional computed tomography: A phantom study

BACKGROUND

The development of ultra-high-resolution CT (U-HRCT) is expected to improve the accuracy of coronary stenosis evaluation. This study aimed to evaluate the accuracy of the stenosis severities of coronary artery phantoms estimated using U-HRCT by comparing them to those estimated with conventional CT.

METHODS

Coronary artery phantoms with non-calcified and calcified lesions were scanned with conventional CT (64-row ​× ​0.625 ​mm) and U-HRCT (32-row ​× ​0.3125 ​mm). The coronary artery phantoms had lumen diameters of 2.0, 3.0, and 4.0 ​mm with non-calcified lesions representing 0%, 25%, 50%, and 75% stenosis and 3.0 and 4.0 ​mm with calcified lesions representing 0%, 25%, 50%, and 75% stenosis. The lumen diameters at the stenotic and non-stenotic regions were measured, and the stenosis severities were compared with the true values.

RESULTS

For non-calcified lesions, conventional CT significantly underestimated the stenosis severity in the phantom showing 75% stenosis with lumen diameters of 2.0 and 3.0 ​mm (p ​< ​0.05), while the estimated stenosis severities were not significantly different from the true values at all settings with U-HRCT. For the calcified lesions, conventional CT overestimated the stenosis severities at all settings (p ​< ​0.05), while U-HRCT yielded estimations closer to the true values, although still with some overestimation (p ​< ​0.05).

CONCLUSION

By using U-HRCT, the estimated stenosis severities of the coronary artery with non-calcified lesion become almost equal to the true value, while those with calcified lesion are still overestimated although they become closer to the true value.

Three-dimensional assessment of coronary high-intensity plaques with T1-weighted cardiovascular magnetic resonance imaging to predict periprocedural myocardial injury after elective percutaneous coronary intervention

BACKGROUND

Periprocedural myocardial injury (pMI) is a common complication of elective percutaneous coronary intervention (PCI) that reduces some of the beneficial effects of coronary revascularization and impacts the risk of cardiovascular events. We developed a 3-dimensional volumetric cardiovascular magnetic resonance (CMR) method to evaluate coronary high intensity plaques and investigated their association with pMI after elective PCI.

METHODS

Between October 2012 and October 2016, 141 patients with stable coronary artery disease underwent T1-weighted CMR imaging before PCI. A conventional 2-dimensional CMR plaque-to-myocardial signal intensity ratio (2D-PMR) and the newly developed 3-dimensional integral of PMR (3Di-PMR) were measured. 3Di-PMR was determined as the sum of PMRs above a threshold of > 1.0 for voxels in a target plaque. pMI was defined as high-sensitivity cardiac troponin T > 0.07 ng/mL.

RESULTS

pMI following PCI was observed in 46 patients (33%). 3Di-PMR was significantly higher in patients with pMI than those without pMI. The optimal 3Di-PMR cutoff value for predicting pMI was 51 PMR*mm3 and the area under the receiver operating characteristic curve (0.753) was significantly greater than that for 2D-PMR (0.683, P = 0.015). 3Di-PMR was positively correlated with lipid volume (r = 0.449, P < 0.001) based on intravascular ultrasound. Stepwise multivariable analysis showed that 3Di-PMR ≥ 51 PMR*mm3 and the presence of a side branch at the PCI target lesion site were significant predictors of pMI (odds ratio [OR], 11.9; 95% confidence interval [CI], 4.6-30.4, P < 0.001; and OR, 4.14; 95% CI, 1.6-11.1, P = 0.005, respectively).

CONCLUSIONS

3Di-PMR coronary assessment facilitates risk stratification for pMI after elective PCI.

TRIAL REGISTRATION

retrospectively registered.

Comparison of the diagnostic performance of 64-slice computed tomography coronary angiography in diabetic and non-diabetic patients with suspected coronary artery disease

BACKGROUND

Diabetics have high prevalence of subclinical coronary artery disease (CAD) with typical characteristics (diffuse disease, large calcifications). Although 64-slice multidetector computed tomography (MDCT) coronary angiography has high diagnostic accuracy to detect CAD, its diagnostic performance in diabetics with suspected CAD is unknown. To compare the diagnostic performance of 64-slice MDCT between diabetics and non-diabetics with suspected CAD scheduled for invasive coronary angiography (ICA).

METHODS

We enrolled one hundred and five diabetic patients (92 men, age 65 +/- 9 years, Group 1) and 105 non-diabetic patients (63 men, age 63+/-5 years, Group 2) with indication to ICA for suspected CAD undergoing coronary 64-slice MDCT before ICA.

RESULTS

In Group 1, the overall feasibility of coronary artery visualization was 93.8%. The most frequent artifact was blooming due to large coronary calcifications (54 artifacts, 67%). In Group 2, the overall feasibility was significantly higher vs. Group 1 (97%, p < 0.0001). In Group 1, the segment-based analysis showed a MDCT sensibility, specificity, positive predictive value, negative predictive value and accuracy for the detection of ≥50% luminal narrowing of 77%, 90%, 70%, 93% and 87%, respectively. In Group 2, all these parameters were significantly higher vs. Group 1. In the patient-based analysis, specificity, negative predictive value and accuracy were significantly lower in Group 1 vs. Group 2.

CONCLUSIONS

Although MDCT has high sensitivity for early identification of significant CAD in diabetics, its diagnostic performance is significantly reduced in these patients as compared to non-diabetics with similar clinical characteristics.

Novel post-processing image for the visualization of the coronary sinus by multidetector-row computed tomography before cardiac resynchronization therapy: edge-enhanced image

BACKGROUND

Before performing cardiac resynchronization therapy (CRT), it is useful to visualize the position of the coronary sinus (CS) orifice where the CS lead is inserted.

METHODS AND RESULTS

A raysum image was created in which the outermost 1-voxel layer of the right atrium (RA) and CS was extracted. This image enabled visualization of the positional relationship between the RA and CS ostium using the same geometry as retrograde CS venography.

CONCLUSION

New post-processing imaging of the CS orifice will make the procedure of CRT safer.

Accuracy of multidetector spiral computed tomography in detecting significant coronary stenosis in patient populations with differing pre-test probabilities of disease

AIM

To investigate the clinical impact of multidetector computed tomography (MDCT) in patients with a low versus a high pre-test likelihood of coronary artery disease (CAD).

MATERIALS AND METHODS

A cohort of 120 patients with suspected CAD, scheduled for conventional coronary angiography, underwent MDCT. Using the American Heart Association (AHA)/American College of Cardiology (ACC) guidelines, the population was divided into two groups: patients with a low (group 1) and a high (group 2) likelihood of CAD.

RESULTS

Analysis of all segments showed a high feasibility (92%), and a patient based-model showed excellent sensitivity and negative predictive values (NPV; both 100%) and acceptable specificity and positive predictive values (PPV; 86 and 90%, respectively), with an accuracy of 94%. Using MDCT in patients with lower pre-test likelihoods of CAD, according to the ACC/AHA guidelines, the accuracy remained high (93%); conversely, in patient groups with a high prevalence of CAD, a non-significant reduction in accuracy (85%) occurred using MDCT. Particularly, MDCT can be used effectively to exclude a diagnosis of CAD because of its high sensitivity and NPV (100%), but shows a significant reduction in specificity (58%). This reduction was due to an increase in the false-positive:true-negative ratio because of the higher percentage of calcified plaque (a relative but non-significant increase in false positives), and the high prevalence of CAD (significant reduction in true negatives). No differences were found between MDCT and quantitative coronary angiography (QCA) concerning the number of vessels narrowed.

CONCLUSION

Because of its excellent sensitivity and specificity in patients with a low pre-test likelihood of CAD, MDCT could be helpful in clinical decision-making in this population.

Effect of Contrast Concentration, Tube Potential and Reconstruction Kernels on MDCT Evaluation of Coronary Stents: an in Vitro Study

INTRODUCTION

To evaluate effect of different kVp, reconstruction kernels and contrast concentrations on stent luminal diameter measurements and luminal contrast attenuation values.

METHODS

Two metallic coronary stents (2.75 mm and 3.0 mm) were deployed in silicone tubes and tubes were filled with diluted iodinated contrast (1:20 dilution of Iohexol 350 mg% to achieve an attenuation value of 550 HU at 120 kVp). The tubes were scanned at 80, 100, 120 and 140 kVp. Each scan acquisition was reconstructed using B10f, B25f, B31f, B36f, B41f, B46f, B60f, and B80f kernels. Scans were repeated using 1:35 contrast dilution (350 HU at 120 kVp). Luminal diameter was measured at mid stent level for each stent, in datasets acquired at different kVp, contrast concentrations, and reconstruction kernels. Luminal attenuation values (HU) were measured at the mid stent level and at a distance of 1 cm from the stent entrance within the tube lumen.

RESULTS

kVp did not have a significant effect on the visualization of stent luminal diameter (P > 0.277). The change in kernel significantly affected the difference in luminal HU values at stent and non-stent levels (P < 0.001), with B46f showing the least difference in HU values. The lower contrast concentration (350 HU) showed substantially less artifactual stent stenosis compared to high contrast concentration (550 HU) (P < 0.001). There was excellent inter-observer agreement for stent luminal diameters and attenuation value measurements (r (2)=0.971, P < 0.001).

CONCLUSIONS

For lower spatial resolution kernels, 120 kVp or 140 kVp provides better estimate of stent lumen. Reconstruction kernels and contrast concentration (HU) have significant effect on visualization of in-stent luminal diameter and artifactual stenosis. In clinical practice, B46f kernel and lower contrast enhancement value ( approximately 350 HU) may be optimal for evaluating the stent lumen.

Three-dimensional X-ray coronary angiography in the porcine model: A feasibility study

RATIONALE AND OBJECTIVES

Three-dimensional high-spatial-resolution angiograms of the coronary arteries were acquired with an electrocardiogram-gated three-dimensional rotational angiography technique on an interventional X-ray system.

MATERIALS AND METHODS

During selective injection of contrast material in the left and right coronary artery, projection images were obtained in eight pigs during a continuous rotation of the X-ray gantry over an angular range of 180 degrees within 8 seconds.

RESULTS

Three-dimensional tomographic reconstruction depicted the proximal, medial, and distal sections of the main arteries as well as the main bifurcations in multiple cardiac phases in all animals.

CONCLUSIONS

For the first time, this feasibility study shows that a three-dimensional angiogram of the coronary arteries can be obtained intraprocedurally in a conventional interventional suite by means of tomographic reconstruction from projection images.

Novel Method of Displaying Coronary CT Angiography Angiographic View

Background A method of displaying coronary computed tomography (CT) angiography, which enables evaluation of coronary artery disease (CAD) with fewer images and is understandable to the third person, is preferable. Methods and Results A maximum intensity projection image was created in which contrast media in the ventricles is eliminated, enabling an overview of CAD in a single 3-dimensional (D) image that can be rotated to be viewed at various angles and is easily understood by a third person. Conclusions A novel method of displaying coronary CT angiography in a single 3-D image has been developed and we believe it should become available for many workstations.