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Unlabelled: Transient ischemic dilation (TID) in the setting of abnormal stress-rest cardiac SPECT myocardial perfusion imaging (MPI) has been linked with increased cardiovascular risk. However, the significance of TID in the setting of an otherwise normal SPECT MPI study has not been clearly established. In this study, cardiac CT was used to evaluate the prevalence of atherosclerotic lesions and the severity of coronary artery stenosis in patients with TID of the left ventricle with or without associated myocardial perfusion defects on SPECT MPI., Methods: The study population consisted of 1,553 consecutive patients who had undergone both cardiac CT and SPECT MPI within 1 mo between January 1, 2006, and September 1, 2011. Patients included in the study group had a pathologic TID value defined as ≥1.18 for men and ≥1.22 for women. Coronary CT angiography was used to evaluate each coronary segment for the presence and composition of atherosclerotic plaque and the degree of coronary stenosis. TID-positive patients were compared with a 2:1 risk-factor-matched-pair control cohort without TID., Results: TID was identified in 30 patients who were compared with TID-negative risk-factor-matched controls (n = 60). When compared with the TID-negative control cohort, TID-positive patients had no significant differences in the presence and extent of atherosclerosis, the degree of coronary artery stenosis, or the calcium score at cardiac CT. Similarly, there were no significant differences in these CT measures in TID-positive patients with a normal perfusion study (n = 20) when compared with TID-negative patients with a normal perfusion study (n = 48). In addition, there was no significant difference in the incidence of major adverse cardiac events when comparing both the TID-positive patients and the TID-negative control cohort and when comparing patients who were TID-positive with normal perfusion with patients who were TID-negative with normal perfusion., Conclusion: The presence of TID with an otherwise normal SPECT MPI study does not translate into a greater extent of coronary artery disease as assessed by cardiac CT or increased risk for future major adverse cardiac events., (© 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

Rationale and Objectives: To investigate the impact of iterative reconstruction in image space (IRIS) on image noise, image quality (IQ), and postprocessing at coronary computed tomography angiography (cCTA) compared to traditional filtered back-projection (FBP)., Materials and Methods: The cCTA results of 50 patients (26 men; 58 ± 15 years, body mass index 31.5 ± 6.7 kg/m²) were investigated using a second-generation dual-source computed tomography system. Scan data were reconstructed with the use of IRIS and FBP algorithms. Two radiologists independently evaluated the reconstructions using automated coronary tree analysis software. Image noise was measured and IQ was rated on a 5-point Likert scale. The number of manual corrections after automated vessel segmentation, the time required to complete segmentation, and the number of missed segments were assessed in both IRIS and FBP reconstructions. Results were compared using paired t-test., Results: IRIS significantly reduced image noise compared to FBP (23.3 ± 8.8 vs. 33.5 ± 13.5 Hounsfield units, P < .001). Subjective IQ improved with IRIS (IRIS 3.2 ± 1.0 vs. FBP 3.0 ± 1.0, P < .05). IRIS decreased the time needed for coronary segmentation from 111.9 ± 40.5 seconds to 95.2 ± 38.2 seconds with FBP (P < .01) and required fewer manual corrections (5.7 ± 3.0 vs. 6.8 ± 3.6, P < .01). The number of missed vessel segments was not significantly different (3.6 ± 1.8 vs. 3.8 ± 1.9, P > .05) between IRIS and FBP, respectively., Conclusions: During cCTA postprocessing, IRIS significantly decreases the time and the number of manual corrections for a complete coronary segmentation compared to FBP. This effect is likely attributable to suppression of image noise by IRIS, which improves the performance of automated vessel segmentation and positively impacts cCTA analysis., (Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.)

Objectives: To evaluate image quality (IQ) of low-radiation-dose paediatric cardiovascular CT angiography (CTA), comparing iterative reconstruction in image space (IRIS) and sinogram-affirmed iterative reconstruction (SAFIRE) with filtered back-projection (FBP) and estimate the potential for further dose reductions., Methods: Forty neonates and children underwent low radiation CTA with or without ECG synchronisation. Data were reconstructed with FBP, IRIS and SAFIRE. For ECG-synchronised studies, half-dose image acquisitions were simulated. Signal noise was measured and IQ graded. Effective dose (ED) was estimated., Results: Mean absolute and relative image noise with IRIS and full-dose SAFIRE was lower than with FBP (P < 0.001), while SNR and CNR were higher (P < 0.001). Image noise was also lower and SNR and CNR higher in half-dose SAFIRE studies compared with full-and half-dose FBP studies (P < 0.001). IQ scores were higher for IRIS, full-dose SAFIRE and half-dose SAFIRE than for full-dose FBP and higher for half-dose SAFIRE than for half-dose FBP (P < 0.05). Median weight-specific ED was 0.3 mSv without and 1.36 mSv with ECG synchronisation. The estimated ED of half-dose SAFIRE studies was 0.68 mSv., Conclusions: IR improves image noise, SNR, CNR and subjective IQ compared with FBP in low-radiation-dose paediatric CTA and allows further dose reductions without compromising diagnostic IQ., Key Points: • Iterative reconstruction techniques significantly improve non-invasive cardiovascular CT in children. • Using half traditional radiation dose image quality is higher with iterative reconstruction. • Iterative reconstruction techniques may allow further radiation reductions in paediatric cardiovascular CT.

Objectives: Performance evaluation of a fully automated system for calculating computed tomography (CT) coronary artery calcium scores from contrast medium-enhanced coronary CT angiography (cCTA) studies., Methods: One hundred and twenty-seven patients (58 ± 11 years, 71 men) who had undergone cCTA as well as an unenhanced CT calcium scoring study where included. Calcium scores were computed from cCTA by an automated image processing algorithm and compared with calcium scores obtained by standard manual assessment of unenhanced CT calcium scoring studies. Results were compared vis-a-vis (1) absolute calcium score values, (2) age-, gender- and race-dependent percentiles, and (3) commonly used calcium score risk classification categories., Results: One hundred and nineteen out of 127 (93.7%) studies were successfully processed. Mean Agatston calcium score values obtained by traditional non-contrast CT calcium scoring studies and derived from contrast medium-enhanced cCTA did not significantly differ (235.6 ± 430.5 vs 262.0 ± 499.5; P > 0.05). Calcium score risk categories and Multi-Ethnic Study of Atherosclerosis (MESA) percentiles showed very high correlation (Spearman rank correlation coefficient = 0.97, P < 0.0001/0.95, P < 0.0001) between the two approaches., Conclusions: Calcium score values automatically computed from cCTA are highly correlated with standard unenhanced CT calcium scoring studies. These results suggest a radiation dose- and time-saving potential when deriving calcium scores from cCTA studies without a preceding unenhanced CT calcium scoring study.

Objectives: Comparison of coronary artery stent assessment with cardiac CT angiography (cCTA) using traditional filtered back projection (FBP) and sinogram affirmed iterative reconstruction (SAFIRE), in both full- and half-radiation dose image data., Methods: Dual-source cCTA studies of 37 implanted stents were reconstructed at full- and half-radiation dose with FBP and SAFIRE. Half-dose data were based on projections from one DSCT detector. In-stent noise, signal-to-noise ratio (SNR), and stent-lumen attenuation increase ratio (SAIR) were measured and image quality graded. Stent volumes were measured to gauge severity of beam hardening artefacts., Results: Full-dose SAFIRE reconstructions were superior to full-dose FBP vis-à-vis in-stent noise (21.2 ± 6.6 vs. 35.7 ± 17.5; P < 0.05), SNR (22.1 ± 8.6 vs. 14.3 ± 6.7; P < 0.05), SAIR (19.6 ± 17.6 vs. 33.4 ± 20.4%; P < 0.05), and image quality (4.2 ± 0.86 vs. 3.5 ± 1.0; P < 0.05). Stent volumes were lower measured with SAFIRE (119.9 ± 53.7 vs. 129.8 ± 65.0 mm(3); P > 0.05). Comparing half-dose SAFIRE with full-dose FBP, in-stent noise (26.7 ± 13.0 vs. 35.7 ± 17.5; P < 0.05) and SNR (18.2 ± 6.9 vs. 14.3 ± 6.7; P < 0.05) improved significantly. SAIR (31.6 ± 24.3 vs. 33.4 ± 20.4%; P > 0.05), stent volume (129.6 ± 57.3 vs. 129.8 ± 65.0 mm(3); P > 0.05), and image quality (3.5 ± 1.0 vs. 3.7 ± 1.1; P > 0.05) did not differ. Radiation dose decreased from 8.7 ± 5.2 to 4.3 ± 2.6 mSv., Conclusions: Iterative reconstruction significantly improves imaging of coronary artery stents by CT compared with FBP, even with half-radiation-dose data.

The use of coronary computed tomography angiography (cCTA) is growing rapidly, in large part because of fast-paced technical innovations that have increased diagnostic accuracy while providing new opportunities for radiation dose reduction. cCTA using recent generation CT scanners has been repeatedly shown to have excellent negative predictive value for ruling out significant coronary stenosis in comparison with invasive coronary angiography (ICA) and is now accepted for this use in selected populations. Current work is increasingly focused on evaluating and optimising radiation dose reduction techniques, the cost-effectiveness of cCTA implementation, and the impact of cCTA on patient management and outcomes. In addition, the potential value of emerging applications, such as atherosclerotic plaque characterisation and myocardial perfusion and viability assessment, are undergoing intense investigation., (© 2011 Blackwell Publishing Ltd.)

A patient underwent laser balloon angioplasty (LBA) combined with local intracoronary heparin therapy for treatment of a high grade stenosis of the mid-portion of the left anterior descending (LAD) coronary artery. Sustained patency of the LBA-treated lesion and no new coronary stenoses were found in a 10-year angiographic follow-up study., ((J Interven Cardiol 2005;18:357-360).)

Normal saline (NS) is commonly used as a coronary catheter flush solution. We tested the hypothesis that intracoronary (i.c.) infusions of lactated Ringer's solution (LR) and LR with 5% dextrose (D5LR), both of which contain potassium and calcium, would be associated with less prominent surface ECG changes compared with i.c. infusions of NS. In 34 patients, 10 mL each of NS, LR, and D5LR at 37 degrees C were infused over 5 sec into the left main coronary artery. A 12-lead ECG was recorded before, continuously during, and after each infusion. Blinded ECG analysis revealed T-wave amplitude changes > 0.2 mV in 94%, 12%, and 3% of patients with the use of i.c. NS, D5LR, and LR, respectively (P < 0.0001, NS vs. D5LR or LR). QT prolongation > 40 msec occurred in 88%, 15%, and 18% of patients with i.c. NS, D5LR, and LR, respectively (P < 0.0001, NS vs. D5LR or LR). QT dispersion was increased by > 40 msec in 26% of patients during i.c. NS infusion compared to only 3% of patients with i.c. LR and D5LR infusions (P < 0.01). In conclusion, i.c. NS infusion is associated with more marked repolarization changes as compared with i.c. LR and D5LR infusions. Since such changes may lower arrhythmogenesis thresholds, the routine use of LR as a coronary catheter flush solution should be considered. Cathet. Cardiovasc. Intervent. 48:359-364, 1999., (Copyright 1999 Wiley-Liss, Inc.)

A formal analysis of the error associated with the use of radiographic diameter measurements in estimating the luminal area of an elliptically-shaped coronary cross-section was performed. When two views are available, the maximum potential error was found to decrease rapidly as the angle between the views increased to 90 degrees, but this error was small (less than 25%) for orthogonal views only for mild degrees of ellipticity (major/minor axis ratio less than 2). Since, for each successive doubling of the number of radiographic views, a stepwise reduction in the potential error by an approximate factor of only one-half was found, a large number of views is required to eliminate the potential error associated with diameter assessment of highly elliptical lumena.

Three-dimensional reconstruction of the coronary tree from a conventional cineangiographic study is limited, in part, by the small number of available cineangiographic views. The potential utility of a maximum entropy iterative algorithm (MENT) for reconstruction of myocardial planes perpendicular to the axis of cineangiographic rotation from a small number (n = 6-18) of cineangiographic views was tested in vitro. The coronary arteries of postmortem human, canine, and calf hearts were filled with a silicone/thorium oxide mold to simulate in vivo angiographic contrast. Thirty-five-millimeter cineradiographs of each heart were obtained at 10 degrees intervals over 180 degrees about a myocardial central axis of rotation under exposure conditions which simulated the clinical setting. Projection data were derived from cinedensitometric scans across the entire myocardial shadow, perpendicular to the axis of rotation in each view, after 512 X 512 digitization with a vidicon camera/digitizer interfaced to a VAX computer. Comparison of MENT-reconstructed images with corresponding anatomic myocardial cross sections indicate that as few as 6 to 12 views can be used to reconstruct the cross sections of the multiple coronary branches (n = 6-11) within a plane of reconstruction.

Problems related to the precision of computerized measurement and analysis of blood vessel diameter from digitized cineangiographic vessel images are described, and shortcomings of the conventional definition of percent stenosis are discussed. Formulae for the precision of percent stenosis, for the minimum significant measurable changes in blood vessel diameter, for the necessary scanning resolution, and for absolute vessel diameter measurement are provided. A Monte Carlo procedure-based technique for assessing the effect of radiographic noise on the location of vessel boundaries within the transverse densitometric image profile is presented and applied to contrast-filled cylindrical phantoms. The results demonstrate the feasibility for achieving subpixel resolution in computerized detection of vessel edges and diameter measurement.

Subjective estimates of the angiographic severity of coronary artery stenoses show variability and inaccuracy. We therefore tested the accuracy of a newly developed computerized image analysis system for quantitating vessel diameter from cineangiograms. Fourteen cylindrical phantoms of known diameter were filled with contrast medium and filmed over a wide range of clinically relevant radiographic conditions in order to develop regression equations that related computer-derived to anatomic diameters. Computer measurements of vessel diameter were unaffected by vessel size, magnification, focal spot size, thickness of scattering medium, kilovolt peak, or location within the radiographic field, but a correction factor was necessary for a small but significant (p less than .01) linear dependence on contrast medium concentration. The accuracy of computerized vessel diameter measurements ranged between +/- 59 and +/- 137 mu for all conditions except for rapid vessel motion and contrast medium concentrations of 50% or less meglumine diatrizoate (Renografin 76), both of which resulted in reduced accuracy as well as in the inability to locate lumen edges of vessels less than 1 mm in diameter.

A cinedensitometric technique for extracting luminal cross-sectional area information is described. Linearization of cineangiographic gray scale with contrast medium thickness was achieved by use of a rotating step-wedge technique. Accuracy of the technique was estimated by filming, over the heart, contrast medium-filled cylindrical phantoms of diameters simulating a wide range of stenosis of a coronary artery. Expressed as (per cent stenosis), a mean error of 3.6 +/- 3.4 per cent between measured and known values of 72 cross-sectional area ratios was found (r = 0.981), and was significantly less than a 7.6 +/- 6.5 per cent error associated with area ratios derived from diameter measurements alone (p less than 0.005).