Journal of Cardiovascular Computed Tomography - Articles in Press

Reversal of Flow in the Pulmonary Artery. High Pitch Spiral as a new method for dose reduction in functional imaging - Accepted Manuscript

Gilbert E. Boswell, Michael Cathey, Richard Campin, Keshav Nayak — 2012-05-14

Fundamentals and applications of magnetic particle imaging - Uncorrected Proof

2012-04-30

Abstract: Magnetic particle imaging (MPI) is a new medical imaging technique which performs a direct measurement of magnetic nanoparticles, also known as superparamagnetic iron oxide. MPI can acquire quantitative images of the local distribution of the magnetic material with high spatial and temporal resolution. Its sensitivity is well above that of other methods used for the detection and quantification of magnetic materials, for example, magnetic resonance imaging. On the basis of an intravenous injection of magnetic particles, MPI has the potential to play an important role in medical application areas such as cardiovascular, oncology, and also in exploratory fields such as cell labeling and tracking. Here, we present an introduction to the basic function principle of MPI, together with an estimation of the spatial resolution and the detection limit. Furthermore, the above-mentioned medical applications are discussed with respect to an applicability of MPI.

Assessment of an iterative reconstruction algorithm (SAFIRE) on image quality in pediatric cardiac CT datasets - Uncorrected Proof

2012-04-30

Background: Pediatric cardiac patients often undergo repeat diagnostic testing, resulting in relatively high cumulative medical radiation exposure. Low-dose CT scanning techniques used to decrease radiation exposure result in reduced image quality.Objective: This study evaluates a prototype iterative reconstruction algorithm, sinogram-affirmed iterative reconstruction (SAFIRE), to determine the effect on qualitative and quantitative measures of image quality in pediatric cardiac CT datasets, compared with a standard weighted filtered back projection (wFBP) algorithm.Methods: Seventy-four datasets obtained on a 128-slice dual-source CT system were evaluated for image quality using both the wFBP and the prototype iterative reconstruction algorithm. Contrast, noise, contrast-to-noise ratio, signal-to-noise ratio, and qualitative image quality were compared between groups. Data were analyzed as medians and 25th and 75th percentiles, and groups were compared with the use of the Wilcoxon singed-rank test or k sample equality of medians test.Results: There was a 34% decrease in noise, a 41% increase in contrast-to-noise ratio, and a 56% increase in signal-to-noise ratio in the prototype iterative reconstruction, compared with wFBP. All differences were statistically significant (P < 0.001). Qualitative measures of image noise and noise texture were also improved in the iterative reconstruction group (P < 0.001 for both). Diagnostic confidence was similar between reconstruction techniques. Median scan dose length product was 15.5 mGy · cm.Conclusion: The prototype iterative reconstruction algorithm studied significantly reduces image noise and improves qualitative and quantitative measures of image quality in low-dose pediatric CT datasets, compared with standard wFBP.

Low-dose, wide-detector array thoracic aortic CT angiography using an iterative reconstruction technique results in improved image quality with lower noise and fewer artifacts - Uncorrected Proof

2012-04-30

Background: Iterative reconstruction techniques (IRTs) may improve image quality for low-dose imaging compared with filtered back projection (FBP) reconstruction.Objectives: We compared the results of an IRT for low-dose thoracic aortic computed tomography (CT) imaging with those from FBP reconstruction.Methods: Data from 50 patients who underwent 256-slice CT for evaluation of the thoracic aorta were reconstructed with FBP and an IRT (iDose4) at 3 noise-reduction strengths (levels 2, 4, and 6). A blinded reader graded image quality (scale, 1–5; 5 = high diagnostic confidence) and the extent of shoulder artifact (scale, 1–5; 5 = no artifact) on all reconstructions. A second reader evaluated a subset of 20 cases to determine interreader and intrareader reproducibility. The mean and SD of attenuation were measured at 5 locations along the thoracic aorta and both subclavian arteries.Results: Image noise (SD of attenuation) improved with IRT relative to FBP (aorta: FBP, 31.4 ± 8.6 HU; IRT level 2, 25.1 ± 6.9 HU; level 4, 21.7 ± 6.2 HU; level 6, 17.2 ± 5.4 HU; P < 0.0001; subclavian arteries: FBP, 92.7 ± 34.6 HU; IRT level 2, 50.1 ± 17.1 HU; level 4, 48.9 ± 18.6 HU; level 6, 45.2 ± 19.2 HU; P < 0.0001), whereas mean attenuation was unchanged. Increasing image quality was observed in the aorta and through the shoulders as the contribution from IRT to the final images increased (P < 0.0001). Significant differences were noted between readers in image quality assessment of the aorta but not through the shoulders.Conclusion: IRT is associated with reduced noise and shoulder artifact and allows for low-dose aortic CT imaging.

Effect of image quality on diagnostic accuracy of noninvasive fractional flow reserve: Results from the prospective multicenter international DISCOVER-FLOW study - Uncorrected Proof

2012-04-30

Background: Fractional flow reserve calculated from coronary CT (FFRCT) is a novel method for determining lesion-specific ischemia.Objective: To assess the effect of CT quality on accuracy of FFRCT, we compared performance of FFRCT with severe stenosis by CT in relation to image quality; heart rate; signal-to-noise ratio (SNR); and common CT artifacts, including calcification, motion, and poor contrast enhancement.Methods: FFRCT was performed on 159 vessels in 103 patients undergoing CT, FFRCT, and FFR. Ischemia was defined as FFRCT and FFR ≤ 0.80, and severe stenosis by CT was defined by ≥50% reduction in luminal diameter. FFRCT and CT stenosis were compared with FFR, which served as the reference.Results: On a vessel basis, accuracy of FFRCT was higher than CT stenosis for satisfactory or poor quality CTs (87.5% vs 64.6%), for heart rates > 65 beats/min (100% vs 52.9%), and for SNR less than the median (26.3) (84.4% vs 64.1%). Accuracy of FFRCT was superior to CT stenosis in the presence of calcification (85.7% vs 66.7%), motion (90.5% vs 57.1%), and poor contrast opacification (100.0% vs 71.4%). Similar relations were observed for exploratory analyses of FFRCT and CT stenosis on a patient basis. In 42 subjects who underwent coronary calcium scanning, accuracy of FFRCT was 77.8% (n = 18), 100% (n = 11), and 100% (n = 13) for coronary calcium scores of 0–100, 101–400, and >400, respectively.Conclusions: Accuracy of FFRCT is superior to CT stenosis for determining lesion-specific ischemia. The performance of FFRCT remains robust across an array of factors known to adversely affect CT quality.

Society News - Corrected Proof

2012-04-25

Automatic Tube Potential Selection with Tube Current Modulation (APSCM) in coronary CT angiography: Comparison of image quality and radiation dose with conventional body mass index-based protocol - Corrected Proof

2012-04-09

Background: The use of Automatic Tube Potential Selection with Tube Current Modulation (APSCM) may lower radiation dose, but it is unknown whether image quality is maintained.Objective: The aim of this study was to evaluate the radiation dose and image quality of APSCM application compared with conventional body mass index (BMI)–based examination protocol for coronary computed tomography angiography (CTA).Methods: Consecutive patients (n = 487) were retrospectively enrolled: 239 patients who underwent coronary CTA with APSCM (APSCM group) and 248 patients who underwent coronary CTA with a BMI-based tube potential (in kV) and tube current-time product (in mAs) protocol (BMI-based group). Comparison of quantitative and qualitative image quality and radiation dose was performed.Results: The use of APSCM found significant reduction in radiation dose compared with the BMI-based protocol, with a significantly more frequent use of 80 kV (P < 0.0001). Diagnostic image quality was maintained, with no significant difference between the 2 groups (P = 0.887).Conclusion: The use of APSCM for coronary CTA significantly reduced radiation dose while maintaining image quality; therefore, it is feasible in daily practice which covers patients with various BMI values.

Coronary computed tomography angiography during arrhythmia: Radiation dose reduction with prospectively ECG-triggered axial and retrospectively ECG-gated helical 128-slice dual-source CT - Corrected Proof

2012-04-09

Background: Arrhythmia during coronary computed tomography angiography (coronary CTA) acquisition increases the risk of nondiagnostic segments and high radiation exposure. An advanced arrhythmia rejection algorithm for prospectively electrocardiogram (ECG)–triggered axial scans using dual-source CT (DSCT) examinations has recently been reported.Objective: We compared image quality and effective dose at DSCT examinations using prospectively ECG-triggered axial scanning with advanced arrhythmia rejection software (PT-AAR) versus retrospectively ECG-gated helical scanning with tube-current modulation (RG-TCM) during arrhythmia.Methods: This was a retrospective case–control study of 90 patients (43 PT-AAR, 47 RG-TCM) with arrhythmia (defined as heart rate variability [HRV] > 10 beats/min during data acquisition) referred for physician-supervised coronary CTA between April 2010 and September 2011. A subset of 22 cases matched for body mass index, HR, HRV, and other scan parameters was identified. Subjective image quality (4-point scale) and effective dose (dose length product method) were compared.Results: PT-AAR was associated with lower effective dose than RG-TCM (4.1 vs 12.6 mSv entire cohort and 4.3 vs 9.1 mSv matched controls; both P < 0.01). Image quality scores were excellent in both groups (3.9 PT-AAR vs 3.6 RG-TCM) and nondiagnostic segment rates were low (0.1% vs 0.6%). Significantly higher image quality scores were found with PT-AAR in the entire cohort (P < 0.05), and in matched controls with high HRV > 28 beats/min (P < 0.05).Conclusions: In patients with variable heart rates, prospectively ECG-triggered axial DSCT with arrhythmia rejection algorithm is feasible and can decrease radiation exposure by ∼50% versus retrospectively ECG-gated helical DSCT, with preserved image quality.

Effect of a novel vendor-specific motion-correction algorithm on image quality and diagnostic accuracy in persons undergoing coronary CT angiography without rate-control medications - Corrected Proof

2012-04-09

Background: Although coronary CT angiography (CTA) shows high diagnostic performance for detection and exclusion of obstructive coronary artery disease, limited temporal resolution of current-generation CT scanners may allow for motion artifacts, which may result in nonevaluable coronary segments.Objective: We assessed a novel vendor-specific motion-correction algorithm for its effect on image quality and diagnostic accuracy.Methods: Thirty-six consecutive patients with severe aortic stenosis undergoing coronary CTA without rate control and invasive coronary angiography as part of an evaluation for transcatheter aortic valve replacement. We compared image quality and diagnostic accuracy between standard (STD) and motion-corrected (MC) reconstructions. Coronary CTAs were interpreted in an intent-to-diagnose fashion by 2 experienced readers; a third reader provided consensus for interpretability and obstructive coronary stenosis (≥50% stenosis). All studies were interpreted with and without motion correction using both 45% and 75% of the R-R interval for reconstructions. Quantitative coronary angiography was performed by a core laboratory.Results: Mean age was 83.0 ± 6.4 years; 47% were men. Overall image quality (graded 1–4) was higher with the use of MC versus STD reconstructions (2.9 ± 0.9 vs 2.4 ± 1.0; P < 0.001). MC reconstructions showed higher interpretability on a per-segment [97% (392/406) vs 88% (357/406); P < 0.001] and per-artery [96% (128/134) vs 84% (112/134); P = 0.002] basis, with no difference on a per-patient level [92% (33/36) vs 89% (32/36); P = 1.0]. Diagnostic accuracy by MC reconstruction was higher than STD reconstruction on a per-segment [91% (370/406) vs 78% (317/406); P < 0.001] and per-artery level [86% (115/134) vs 72% (96/134); P = 0.007] basis, with no significant difference on a per-patient level [86% (31/36) vs 69% (25/36); P = 0.16].Conclusions: The use of a novel MC algorithm improves image quality, interpretability, and diagnostic accuracy in persons undergoing coronary CTA without rate-control medications.

State-of-the-art in CT hardware and scan modes for cardiovascular CT - Uncorrected Proof

2012-04-09

Abstract: Multidetector row computed tomography (CT) allows noninvasive anatomic and functional imaging of the heart, great vessels, and coronary arteries. In recent years, there have been several advances in CT hardware, which have expanded the clinical utility of CT for cardiovascular imaging; such advances are ongoing. This review article from the Society of Cardiovascular Computed Tomography Basic and Emerging Sciences and Technology Working Group summarizes the technical aspects of current state-of-the-art CT hardware and describes the scan modes this hardware supports for cardiovascular CT imaging.

President’s Page: Tipping point - Uncorrected Proof

James K. Min — 2012-04-06

Dear Colleagues: In the previous issues of the President’s Page, we focused on several of the active initiatives of the Society of Cardiovascular Computed Tomography (SCCT), having discussed the efforts of the SCCT to focus on increasing international growth of our membership, the integration of fellows and residents in training into a dedicated governance structure within the SCCT, and the SCCT’s realization of the ever-expanding indications of cardiovascular CT, coupled with formal application for dedicated Category III CPT codes for CT myocardial perfusion imaging.