Lower Patient Radiation Exposure Research Articles

Improving Image Quality and Diagnostic Performance of CCTA in Patients with Challenging Heart Rate Conditions Using a Deep Learning-Based Motion Correction Algorithm.

Challenging HR conditions, such as elevated Heart Rate (HR) and Heart Rate Variability (HRV), are major contributors to motion artifacts in Coronary Computed Tomography Angiography (CCTA). This study aims to assess the impact of a deep learning-based motion correction algorithm (MCA) on motion artifacts in patients with challenging HR conditions, focusing on image quality and diagnostic performance of CCTA. This retrospective study included 240 patients (mean HR: 88.1 ± 14.5 bpm; mean HRV: 32.6 ± 45.5 bpm) who underwent CCTA between June, 2020 and December, 2020. CCTA images were reconstructed with and without the MCA. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured to assess objective image quality. Subjective image quality was evaluated by two radiologists using a 5-point scale regarding vessel visualization, diagnostic confidence, and overall image quality. Moreover, all vessels with scores ≥ 3 were considered clinically interpretable. The diagnostic performance of CCTA with and without MCA for detecting significant stenosis (≥ 50%) was assessed in 34 patients at both per-vessel and per-patient levels, using invasive coronary angiography as the reference standard. The MCA significantly improved subjective image quality, increasing the vessel interpretability from 89.9% (CI: 0.88-0.92) to 98.8% (CI: 0.98-0.99) (p < 0.001). The use of MCA resulted in significantly higher diagnostic performance in both patient-based (AUC: 0.83 vs. 0.58, p = 0.04) and vessel-based (AUC: 0.92 vs. 0.81, p < 0.001) analyses, with the vessel-based accuracy notably increased from 79.4% (CI: 0.72-0.86) to 91.2% (CI: 0.85-0.95) (p = 0.01). There were no significant differences in objective image quality between the two reconstructions. The mean effective dose in this study was 2.8 ± 1.1 mSv. The use of MCA allows for obtaining high-quality CCTA images and superior diagnostic performance with low radiation exposure in patients with elevated HR and HRV.

Catheter ablation of atrial fibrillation in situs inversus dextrocardia: Challenge, improved procedure, outcomes, and literature review.

Catheter ablation for atrial fibrillation (AF-CA) in patients with situs inversus dextrocardia (SID) can be challenging because of the contrary anatomy and associated anomalies. Cases and literature regarding AF-CA in SID are rare and provide little information. Our study aims to present an improved procedure, ablation strategies, and evaluate the safety and outcomes of AF-CA in patients with AF and SID. A total of 10 patients with AF-SID (mean age, 60.4 ± 15.7 years; six paroxysmal AF, four persistent atrial fibrillation [PeAF]) were enrolled. For the improved procedure, images obtained by preacquired computed tomography and three-dimensional electroanatomical mapping, integrating intracardiac echocardiography, and x-ray imaging data are necessary to optimize the transseptal puncture and ablation procedure. All patients successfully underwent 13 AF-CA procedures without complications, including three patients received repeat procedures. However, two PeAF patients presented sick sinus syndrome (SSS) after the AF-CA procedure, and one underwent permanent pacemaker implantation therapy during hospitalization. During the follow-up period (6-72 months), the outcomes were not favorable: three patients (30%) maintained sinus rhythm (SR) after the initial procedure; after repeated procedures, the overall SR rate was 40% (four patients). With the improved strategy, AF-CA can be safely and effectively performed with low radiation exposure in patients with SID. However, the long-term outcomes were not favorable, even when managed at a tertiary center by a team of specialists. Moreover, patients with PeAF might also have masked SSS, which should be carefully considered.

Three-dimensional guided selective right ventricular septal pacing preserves ventricular systolic function and synchrony in pediatric patients

Nonfluoroscopic 3-dimensional (3D) electroanatomic mapping systems (EAMs) have been developed to guide cardiac catheter navigation and reduce fluoroscopy. Selective right ventricular (RV) septal pacing could prevent pacing-induced left ventricular (LV) dysfunction. The purpose of this study was to determine whether EAM-guided selective RV septal pacing preserves LV contractility/synchrony in pediatric patients with complete atrioventricular block (CAVB) and no other congenital heart defects. Prospective analysis of children/adolescents who underwent EAM-guided selective RV pacing was performed. A 3D pacing map guided ventricular lead implantation at septal sites with narrow paced QRS. Serial echocardiograms were obtained after pacemaker implantation to monitor for function (volumes, ejection fraction [EF], global longitudinal/circumferential strain) and synchrony (interventricular mechanical delay, septal to posterior wall motion delay, systolic dyssynchrony index). Data are reported as median (25th-75th percentile). Thirty-two CAVB patients (age 9.8 [7.0-14.0] years; 11 with a previous pacing system) underwent selective RV septal pacing (13 DDD, 19 VVIR pacemaker; midseptum 22, parahisian 7, RV outflow tract 3) with narrow paced QRS (110 [100-120] ms) and low radiation exposure. Follow-up over 24 (5-33) months showed preserved LV function and synchrony, without significant differences between pacing sites (midseptum-parahisian) and mode (VVIR-DDD). EF decreased after implantation in patients without previous pacing, although values were mainly within normal limits. Three parahisian patients underwent early lead repositioning. EAM-guided selective RV septal pacing is a feasible technique associated with preserved LV systolic function and synchrony and low radiation exposure in pediatric patients with CAVB.

ACCURACY OF MYOCARDIAL NATIVE T2 FOR THE DIAGNOSIS OF ACTIVE CARDIAC SARCOIDOSIS

SESSION TITLE: Late-breaking Abstract Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: To determine the accuracy of native T2 on cardiac magnetic resonance (CMR) in the diagnosis of active cardiac sarcoidosis when compared to combined clinical diagnosis and cardiac positron emission tomography (PET) as the gold standard. METHODS: 24 patients were identified who had received both cardiac MRI and PET within a 6-month period between May 2017 and May 2020. 6 patients were excluded due to lack of active cardiac sarcoidosis at the time of imaging. T2 and PET American Heart Association (AHA) left ventricular segment mapping was loaded onto polar plots and compared with the gold standard. Statistical analysis was performed in XLSTAT including logistic regression and two-tailed T tests. RESULTS: A total of 18 patients were included in the analyses. Five models were found that adequately predicted the diagnosis of active cardiac sarcoidosis: PET SUV > 2.5 (R2 = 0.132, AUC = 0.722), max SUV (R2 = 0.358, AUC = 0.833), T2 > 55 msec (R2 = 0.294, AUC = 0.722), T2 >59.4 msec (R2 = 0.258, AUC = 0.736), and max T2 (R2 = 0.408, AUC = 0.875). The best model was using max T2 value as a predictor of active cardiac sarcoidosis, which suggested a 95% probability of a positive test at 59.4 msec. The odds ratio for every integer increase in max T2 msec was 2.098 (95% CI 0.92 – 4.78). CONCLUSIONS: The use of T2 imaging is at least as predictive of active cardiac sarcoidosis as PET in three different models. The best fit model was using T2 max. T2 > 55 msec was the most sensitive model (91.7%), while T2 > 59.4 was the most specific (100%). At our institution, the optimal diagnostic threshold lies between these two values. CLINICAL IMPLICATIONS: Quantifiable T2 parameters indicative of active cardiac sarcoid can be coupled with late gadolinium enhancement on CMR to diagnose both active and inactive cardiac sarcoidosis using a single imaging modality. This would ultimately allow for fewer imaging studies and lower patient radiation exposure. DISCLOSURES: Owner/Founder relationship with YellowDot Innovations, LLC Please note: $20001 - $100000 Added 07/16/2020 by Jeremy Burt, source=Web Response, value=Ownership interest No relevant relationships by Jordan Chamberlin, source=Web Response Research Grant relationship with Medtronic Please note: $5001 - $20000 Added 07/16/2020 by Brian Houston, source=Web Response, value=Grant/Research Support No relevant relationships by Ennis James, source=Web Response No relevant relationships by Madison Kocher, source=Web Response No relevant relationships by William Rieter, source=Web Response No relevant relationships by Madalyn Snoddy, source=Web Response No relevant relationships by Natalie Stringer, source=Web Response Grant recipient relationship with Siemens Healthcare Please note: >$100000 Added 07/17/2020 by Akos Varga-Szemes, source=Web Response, value=Grant/Research Support Consultant relationship with Elucid Bioimaging Please note: $5001 - $20000 Added 07/17/2020 by Akos Varga-Szemes, source=Web Response, value=Consulting fee Consultant relationship with Bayer Healthcare Please note: $1001 - $5000 Added 07/17/2020 by Akos Varga-Szemes, source=Web Response, value=Consulting fee No relevant relationships by Jeffrey Waltz, source=Web Response

Low-Dose Coronary CT Angiography in Patients with Atrial Fibrillation: Comparison of Image Quality and Radiation Exposure with Two Different Approaches

To evaluate image quality, coronary interpretability and radiation exposure of coronary CT angiography (CCTA) performed in patients with atrial fibrillation (AF) with the latest scanner generation, comparing two different technical approaches. A new scanner that combines a 0.23mm spatial resolution, a new generation of iterative reconstruction, fast gantry rotation time and the intracycle motion-correction algorithm to improve the temporal resolution was recently introduced in the clinical field. We enrolled 105 consecutive patients with chronic AF who performed CCTA with a whole-heart coverage high-definition CT scanner (16-cm z-axis coverage with 256 detector rows, 0.28s gantry rotation time). Five of them were excluded for impaired renal function. Patients were randomized between a double acquisition protocol (50 patients, group 1) or a single acquisition protocol (50 patients, group 2). The image quality, coronary segment interpretability and effective dose (ED) of CCTA were assessed. The mean HR during the scan was 85.6±21bpm in group 1vs. 83.7±23bpm in Group 2, respectively (p<ns). In group 2, overall image quality was high and comparable with that of group 1 (Likert scale=3.2±1.4vs. 3.3±1.2, p=ns, in group 1 and 2, respectively). Coronary interpretability was high and similar between the two groups (97.5% and 97.1% in group 1 and 2, p =ns, respectively). Mean ED was significantly higher in group 1 than in group 2 (5.3±1.8mSv vs. 2.7±0.7mSv, p<0.001). The novel whole-heart coverage CT scanner allows to perform CCTA with a single-acquisition protocol with high image quality and low radiation exposure in AF patients.

Diagnostic accuracy of low-dose dual-source cardiac computed tomography as compared to surgery in univentricular heart patients

BackgroundTo evaluate the ability of low radiation dose dual-source computed tomography (DSCT) to depict the features of morphological univentricular heart and to define accuracy by comparing findings with surgery.MethodsLow radiation dose dual-source cardiac computed tomography (CCT) of 33 cases of functional univentricular heart preliminary diagnosis by echocardiography compared with the results of surgery were retrospectively analyzed (aged 1 day to 4 years, median 5 months). The appropriate dose reduction strategies and iterative reconstruction were applied.ResultsThirty three univentricular heart patients were classified into three types according to Anderson’s classification method, including 16 cases (48.5%) univentricular of right ventricular type with rudimentary chamber of left ventricle, 11 cases (33.3%) univentricular of left ventricular type with rudimentary chamber of right ventricle and 6 cases (18.2%) univentricular heart of indeterminate type without rudimentary chamber. The extracardiac malformation such as hypoplastic aortic arch, coronary artery fistula, total anomalous pulmonary venous returns or hypoplastic lung were presented frequently. The overall sensitivity and specification of cardiac CT was 100% compared to the results of surgery. The procedural dose-length product was 18 ± 5 mGy-cm, and unadjusted and adjusted radiation doses were 0.25 and 0.64 mSv, respectively.ConclusionCardiac CT can diagnose accurately and be performed with a low radiation exposure in patients with the functional univentricular heart disease. The aorta, pulmonary artery and lung can be evaluated completely and simultaneously as well. Cardiac CT is an effective advanced non-invasive imaging modality to comprehensive evaluation the functional univentricular heart patients, particularly if cardiac MRI poses a high risk or is contraindicated.

Image quality and radiation dose of coronary CT angiography performed with whole-heart coverage CT scanner with intra-cycle motion correction algorithm in patients with atrial fibrillation.

To evaluate image quality, coronary evaluability and radiation exposure of coronary CT angiography (CCTA) performed with whole-heart coverage cardiac-CT in patients with atrial fibrillation (AF). We prospectively enrolled 164 patients with AF who underwent a clinically indicated CCTA with a 16-cm z-axis coverage scanner. In all patients CCTA was performed using prospective ECG-triggering with targeted RR interval. We evaluated image quality, coronary evaluability and effective dose (ED). Patients were divided in two subgroups based on heart rate (HR) during imaging. Group 1: 64 patients with low HR (<75 bpm), group 2: 100 patients with high HR (≥75 bpm). Written informed consent was obtained from all patients and the institutional ethics committee approved the study protocol. In a segment-based analysis, coronary evaluability was 98.4 % (2,577/2,620 segments) in the whole population, without significant differences between groups (1,013/1,024 (98.9 %) and 1,565/1,596 (98.1 %), for groups 1 and 2, respectively, p=0.15). Mean ED was similar in both groups (3.8±1.9 mSv and 3.9±2.1 mSv in groups 1 and 2, respectively, p=0.75) CONCLUSIONS: The whole-heart-coverage scanner could evaluate coronary arteries with high image quality and without increase in radiation exposure in AF patients, even in the high HR group. • Last-generation CT scanner improves coronary artery assessment in AF patients. • The new CT scanner enables low radiation exposure in AF patients. • Diagnostic ICA maybe avoided in AF patients with suspected CAD. • Whole-heart coverage CT scanner enables low radiation exposure in AF patients.

Cardiovascular CT for evaluation of single-ventricle heart disease: risks and accuracy compared with interventional findings.

We sought to evaluate the risk and image quality from cardiovascular CT in patients across all stages of single-ventricle palliation, and to define accuracy by comparing findings with intervention and surgery. Consecutive CT scans performed in patients with single-ventricle heart disease were retrospectively reviewed at a single institution. Diagnosis, sedation needs, estimated radiation dose, and adverse events were recorded. Anatomical findings, image quality (1-4, 1=optimal), and discrepancy compared with interventional findings were determined. Results are described as medians with their 25th and 75th percentiles. From January, 2010 to August, 2015, 132 CT scans were performed in single-ventricle patients of whom 20 were neonates, 52 were post-Norwood, 15 were post-Glenn, and 45 were post-Fontan. No sedation was used in 76 patients, 47 were under minimal or moderate sedation, and nine were under general anaesthesia. The median image quality score was 1.2. The procedural dose-length product was 24 mGy-cm, and unadjusted and adjusted radiation doses were 0.34 (0.2, 1.8) and 0.82 (0.55, 1.88) mSv, respectively. There was one adverse event. No major and two minor discrepancies were noted at the time of 79 surgical and 10 catheter-based interventions. Cardiovascular CT can be performed with a low radiation exposure in patients with single-ventricle heart disease. Its accuracy compared with that of interventional findings is excellent. CT is an effective advanced imaging modality when a non-invasive pathway is desired, particularly if cardiac MRI poses a high risk or is contraindicated.

Robotic technology in interventional cardiology: Current status and future perspectives

Robotic technology has been utilized in cardiovascular medicine for over a decade, and over that period, its use has been expanded to percutaneous coronary and peripheral vascular interventions. The safety and feasibility of robotically assisted percutaneous cardiovascular interventions has been demonstrated in studies including simple to complex coronary lesions, and both iliac and femoropopliteal lesions. These reports have shown that robotically assisted PCI significantly reduces operator exposure to harmful ionizing radiation without a detrimental effect on procedural success or clinical efficacy. Additionally, the use of robotics has the intuitive benefit of alleviating the risk of orthopedic injuries faced by interventional operators. In addition to the interventional operator benefits, robotically assisted intervention has the potential for patient level benefit by allowing more accurate lesion length measurement, precise stent placement, and lower patient radiation exposure. However, further investigation is required to fully elucidate these potential benefits.

Radial versus femoral access for coronary angiography and intervention is associated with lower patient radiation exposure in high-radial-volume centres: Insights from the RAY’ACT-1 study

Literature suggests that radial access is associated with higher radiation doses than femoral access. To compare patient radiation exposure during coronary angiography (CA) and percutaneous coronary intervention (PCI) with radial versus femoral access. RAY'ACT is a nationwide, multicentre, French survey evaluating patient radiation in interventional cardiology. Variables of patient exposure from 21,675CAs and 17,109PCIs performed at 44centres during 2010 were analysed retrospectively. Radial access was used in 71% of CAs and 69% of PCIs. Although median fluoroscopy times were longer for radial versus femoral access (CA, 3.8 vs 3.5minutes [P<0.001]; PCI, 10.4 vs 10.1minutes [P=0.001]), the Kerma-area product (KAP) was lower with radial access (CA, 26.8 vs 28.1Gy·cm2; PCI, 55.6 vs 59.4Gy·cm2; both P=0.001). Differences in KAP remained significant in the multivariable analysis (P<0.01), and in a propensity score-matched analysis (P=0.01). A significant interaction was found between KAP and the percentage of procedures with radial access by centre (P<0.001). KAP was higher by radial versus femoral access in low-radial-volume centres, and lower in high-radial-volume centres. Radiation protection techniques, such as the use of low frame rates (7.5frame/s), were used more frequently in high-radial-volume radial centres. In this multicentre study, radial access was associated with lower radiation doses to patient than femoral access in high-radial-volume centres. Provided that radioprotection methods are implemented, radial access could be associated with lower patient radiation exposure.

Performance of cardiac cadmium-zinc-telluride gamma camera imaging in coronary artery disease: a review from the cardiovascular committee of the European Association of Nuclear Medicine (EANM)

The trade-off between resolution and count sensitivity dominates the performance of standard gamma cameras and dictates the need for relatively high doses of radioactivity of the used radiopharmaceuticals in order to limit image acquisition duration. The introduction of cadmium-zinc-telluride (CZT)-based cameras may overcome some of the limitations against conventional gamma cameras. CZT cameras used for the evaluation of myocardial perfusion have been shown to have a higher count sensitivity compared to conventional single photon emission computed tomography (SPECT) techniques. CZT image quality is further improved by the development of a dedicated three-dimensional iterative reconstruction algorithm, based on maximum likelihood expectation maximization (MLEM), which corrects for the loss in spatial resolution due to line response function of the collimator. All these innovations significantly reduce imaging time and result in a lower patient's radiation exposure compared with standard SPECT. To guide current and possible future users of the CZT technique for myocardial perfusion imaging, the Cardiovascular Committee of the European Association of Nuclear Medicine, starting from the experience of its members, has decided to examine the current literature regarding procedures and clinical data on CZT cameras. The committee hereby aims 1) to identify the main acquisitions protocols; 2) to evaluate the diagnostic and prognostic value of CZT derived myocardial perfusion, and finally 3) to determine the impact of CZT on radiation exposure.

Image quality and radiation dose of dual-source CT cardiac angiography using prospective ECG-triggering technique in pediatric patients with congenital heart disease.

BackgroundAll studies involving use of ionizing radiation should be performed in accordance with the ALARA (As Low As Reasonably Achievable) principle, especially in children. In this study, the prospective ECG triggering technique with low voltage was used in dual-source computed tomography (DSCT) angiography to investigate if image quality with low radiation dose could be satisfactory in pediatric patients with congenital heart disease.MethodsSixty pediatric patients with suspected congenital cardiovascular anomalies were enrolled prospectively in the study. They were randomly assigned to two groups for DSCT angiography. Group A were scanned by prospective ECG-triggering computed tomography angiography (CTA) with 80 kV tube voltage, while group B by used non-ECG-gated CTA with the same tube voltage. The anomaly accuracy was evaluated based on the surgical and/or conventional cardiac angiography findings. The overall image quality was assessed on a five-point scale. And the diagnostic accuracy and radiation dose was evaluated in both groups.ResultsThere were 127 cardiovascular anomalies in Group A and 108 in Group B. The mean subjective image quality and diagnostic accuracy between these two groups were significantly different (P = 0.007 and 0.011, respectively). The mean effective dose in Group A and Group B was 0.38 ± 0.13 mSv and 0.35 ± 0.17 mSv, respectively. But there was no significant difference between two groups (P = 0.197).ConclusionsThe prospective ECG triggering technique in DSCT scan can offer better image quality and diagnostic accuracy with low radiation exposure in pediatric patients with congenital heart diseases. This technique has potential to become a new clinical routine in pediatric cardiac computed tomography (CT) imaging.

Model-based segmentation in orbital volume measurement with cone beam computed tomography and evaluation against current concepts.

Objective determination of the orbital volume is important in the diagnostic process and in evaluating the efficacy of medical and/or surgical treatment of orbital diseases. Tools designed to measure orbital volume with computed tomography (CT) often cannot be used with cone beam CT (CBCT) because of inferior tissue representation, although CBCT has the benefit of greater availability and lower patient radiation exposure. Therefore, a model-based segmentation technique is presented as a new method for measuring orbital volume and compared to alternative techniques. Both eyes from thirty subjects with no known orbital pathology who had undergone CBCT as a part of routine care were evaluated (n = 60 eyes). Orbital volume was measured with manual, atlas-based, and model-based segmentation methods. Volume measurements, volume determination time, and usability were compared between the three methods. Differences in means were tested for statistical significance using two-tailed Student's t tests. Neither atlas-based (26.63 ± 3.15 mm(3)) nor model-based (26.87 ± 2.99 mm(3)) measurements were significantly different from manual volume measurements (26.65 ± 4.0 mm(3)). However, the time required to determine orbital volume was significantly longer for manual measurements (10.24 ± 1.21 min) than for atlas-based (6.96 ± 2.62 min, p < 0.001) or model-based (5.73 ± 1.12 min, p < 0.001) measurements. All three orbital volume measurement methods examined can accurately measure orbital volume, although atlas-based and model-based methods seem to be more user-friendly and less time-consuming. The new model-based technique achieves fully automated segmentation results, whereas all atlas-based segmentations at least required manipulations to the anterior closing. Additionally, model-based segmentation can provide reliable orbital volume measurements when CT image quality is poor.

Evaluation of high-pitch dual-source CT angiography for evaluation of coronary and carotid-cerebrovascular arteries

ObjectivesTo explore the feasibility and diagnostic accuracy of a combined one-step high-pitch dual-source computed tomography angiography (CTA) technique for evaluation of coronary and carotid-cerebrovascular arteries. Materials and methods85 symptomatic patients suspected of coronary artery and cerebrovascular disease referred for simultaneous coronary and carotid-cerebrovascular CTA were included. Additional invasive angiography of the coronary and cerebral arteries was performed within 30 days in 23 and 13 patients, respectively. The objective parameters of image quality, the mean CT attenuations, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were evaluated. The subjective image quality of vessels was also assessed by 2 independent radiologists blinded to the patients’ medical history and scan protocols. The diagnostic performance of CTA including sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the detection or exclusion of significant artery stenosis was calculated using the chi-squared test of contingency and correlated with the results of invasive angiography representing the standard of reference. ResultsImage quality was rated excellent (score 1) in 95.3% (1074/1127), good (score 2) in 3.3% (37/1127), adequate (score 3) in 1.0% (11/1127), and non-diagnostic (score 4) in 0.4% (5/1127) of coronary segments. Image quality of carotid and cerebral vessels was rated mostly excellent (score 1, 95.12% [78/82]; score 2, 3.66% [3/82]; score 3, 1.22% [1/82]). The sensitivity, specificity, PPV and NPV for the detection of coronary stenosis were 92.2% (81.1–97.7%), 95.2% (91.7–97.5%), 79.6% (67.1–89.1%) and 98.3% (95.8–99.5%), respectively. For the detection of carotid and cerebral artery stenosis, CTA demonstrated a sensitivity of 92.8% (80.5–98.4%), a specificity of 93.5% (88.3–96.8%), a PPV of 79.6% (65.6–89.7%) and a NPV of 97.9% (94.1–99.5%). The effective radiation dose was 1.42±0.44mSv (range, 0.88–3.35mSv). ConclusionDual-source CT with a one-step high-pitch scan protocol for combined coronary and carotid-cerebrovascular CTA provides good image quality and a high diagnostic accuracy for the simultaneous evaluation of coronary, carotid and cerebral artery stenosis and may be a useful examination with relatively low radiation exposure in patients with suspected coronary and carotid-cerebrovascular disease.

Personalized Technologist Dose Audit Feedback for Reducing Patient Radiation Exposure From CT

The aim of this study was to determine whether providing radiologic technologists with audit feedback on doses from CT examinations they conduct and education on dose-reduction strategies reduces patients' radiation exposure. This prospective, controlled pilot study was conducted within an integrated health care system from November 2010 to October 2011. Ten technologists at 2 facilities received personalized dose audit reports and education on dose-reduction strategies; 9 technologists at a control facility received no intervention. Radiation exposure was measured by the dose-length product (DLP) from CT scans performed before (n = 1,630) and after (n = 1,499) the intervention and compared using quantile regression. Technologists were surveyed before and after the intervention. For abdominal CT, DLPs decreased by 3% to 12% at intervention facilities but not at the control facility. For brain CT, DLPs significantly decreased by 7% to 12% at one intervention facility; did not change at the second intervention facility, which had the lowest preintervention DLPs; and increased at the control facility. Technologists were more likely to report always thinking about radiation exposure and associated cancer risk and optimizing settings to reduce exposure after the intervention. Personalized audit feedback and education can change technologists' attitudes about, and awareness of, radiation and can lower patient radiation exposure from CT imaging.

Electronic apex locator: A comprehensive literature review - Part I: Different generations, comparison with other techniques and different usages

Introduction: To compare electronic apex locators (EAL) with others root canal determination techniques and evaluate other usage of this devices. Materials and Methods: Tooth apex, Dental instrument, Odontometry, Electronic medical, and Electronic apex locator were searched as primary identifiers via Medline/PubMed, Cochrane library, and Scopus data base up to 30 July 2013. Original articles that fulfilled the inclusion criteria were selected and reviewed. Results: Out of 402 relevant studies, 183 were selected based on the inclusion criteria. In this part, 108 studies are presented. Under the same conditions, no significant differences could be seen between different EALs of one generation. The application of EALs can result in lower patient radiation exposure, exact diagnosing of fractures, less perforation, and better retreatment. Conclusions: EALs were more accurate than other techniques in root canal length determination.

Prospective-triggered sequential dual-source end-systolic coronary CT angiography for patients with atrial fibrillation: A feasibility study

BackgroundObtaining diagnostic coronary CT angiography with low radiation exposure in patients with irregular heart rhythms such as atrial fibrillation (AF) remains challenging. ObjectiveWe evaluated image quality and inter-reader variability with the use of prospective electrocardiographic (ECG)-triggered sequential dual-source acquisition at end systole for coronary artery disease (CAD) evaluation in patients with AF. MethodsThirty consecutive patients with AF who underwent prospective ECG-triggered sequential dual-source acquisition were evaluated. Images were reconstructed every 50 milliseconds from 250 to 400 milliseconds after the R wave. Two independent, blinded readers evaluated the coronaries for image quality on a 5-point scale (worst to best) and stenosis on 5-point semiquantitative (none to severe) and binary scales (>50% or <50%). Diagnostic image quality was graded for each reconstruction. ResultsEleven patients (37%) had significant (≥50% stenosis) CAD. Average heart rate was 82 ± 20 beats/min and variability range was 71 ± 22 beats/min. Mean effective radiation dose was 6.5 ± 2.4 mSv. Diagnostic image quality was noted in 97.9% of 304 coronary segments with median image quality of 3.0. The 300-millisecond reconstruction phase provided the highest image quality; 70% of patients showed diagnostic image quality. Combination of all phases (250–400 milliseconds) performed significantly better than single or other phase combinations (P < 0.0005 for all comparisons). Inter-reader variability for stenosis detection was excellent, with 98.4% concordance by using a binary scale (50% stenosis cutoff). ConclusionsProspective ECG-triggered sequential dual-source CT acquisition with the use of end-systolic acquisition provides diagnostic image quality with potentially low radiation doses for evaluation of CAD in patients with AF. Use of multiple end-systolic phases over a 150-millisecond window improves diagnostic image quality.

Diagnostic accuracy of combined coronary angiography and adenosine stress myocardial perfusion imaging using 320-detector computed tomography: pilot study

To determine the diagnostic accuracy of combined 320-detector row computed tomography coronary angiography (CTA) and adenosine stress CT myocardial perfusion imaging (CTP) in detecting perfusion abnormalities caused by obstructive coronary artery disease (CAD). Twenty patients with suspected CAD who underwent initial investigation with single-photon-emission computed tomography myocardial perfusion imaging (SPECT-MPI) were recruited and underwent prospectively-gated 320-detector CTA/CTP and invasive angiography. Two blinded cardiologists evaluated invasive angiography images quantitatively (QCA). A blinded nuclear physician analysed SPECT-MPI images for fixed and reversible perfusion defects. Two blinded cardiologists assessed CTA/CTP studies qualitatively. Vessels/territories with both >50 % stenosis on QCA and corresponding perfusion defect on SPECT-MPI were defined as ischaemic and formed the reference standard. All patients completed the CTA/CTP protocol with diagnostic image quality. Of 60 vessels/territories, 17 (28 %) were ischaemic according to QCA/SPECT-MPI criteria. Sensitivity, specificity, PPV, NPV and area under the ROC curve for CTA/CTP was 94 %, 98 %, 94 %, 98 % and 0.96 (P < 0.001) on a per-vessel/territory basis. Mean CTA/CTP radiation dose was 9.2 ± 7.4 mSv compared with 13.2 ± 2.2 mSv for SPECT-MPI (P < 0.001). Combined 320-detector CTA/CTP is accurate in identifying obstructive CAD causing perfusion abnormalities compared with combined QCA/SPECT-MPI, achieved with lower radiation dose than SPECT-MPI. • Advances in CT technology provides comprehensive anatomical and functional cardiac information. • Combined 320-detector CTA/adenosine-stress CTP is feasible with excellent image quality. • Combined CTA/CTP is accurate in identifying myocardial ischaemia compared with QCA/SPECT-MPI. • Combined CTA/CTP results in lower patient radiation exposure than SPECT-MPI. • CTA/CTP may become an established imaging technique for suspected CAD.

Simultaneous PET/MR will replace PET/CT as the molecular multimodality imaging platform of choice

Suggestions for topics suitable for these Point/Counterpoint debates should be addressed to Colin G. Orton, Professor Emeritus, Wayne State University, Detroit: ortonc@comcast.net. Persons participating in Point/Counterpoint discussions are selected for their knowledge and communicative skill. Their positions for or against a proposition may or may not reflect their personal opinions or the positions of their employers.