Radiation dose of chaperones during common pediatric computed tomography examinations

Background One main challenge in pediatric imaging is to reduce motion artifacts by calming young patients. To that end, the Radiological Society of North America (RSNA) as early as 1997 stated the necessity of adults accompanying their child during the child’s examination. Nonetheless, current research lacks data regarding radiation dose to these chaperones. Objective The aim of this study was to measure the radiation dose of accompanying adults during state-of-the-art pediatric CT protocols. Materials and methods In addition to a 100-kV non-contrast-enhanced chest CT (Protocol 1), we performed a 70-kV contrast-enhanced chest protocol (Protocol 2) using a third-generation dual-source CT. We acquired data on the radiation dose around the scanner using digital dosimetry placed right at the gantry, 1 m away, as well as beside the gantry. We acquired the CT-surrounding radiation dose during scanning of a pediatric phantom as well as 12 pediatric patients. Results After conducting 10 consecutive phantom scans using Protocol 1, we found the location with the highest cumulative dose acquired was right next to the gantry opening, at 3 μSv. Protocol 2 showed highest cumulative dose of 2 μSv at the same location. For Protocol 1, the location with the highest radiation doses during pediatric scans was right next to the gantry opening, with doses of 0.75±0.70 μSv. For Protocol 2, the highest radiation was measured 1 m away at 0.50±0.60 μSv. No radiation dose was measured at any time beside the gantry. Conclusion Our results provide proof that chaperones receive low radiation doses during state-of-the-art CT examinations. Given knowledge of these values as well as the optimal spots with the lowest radiation doses, parents as well as patients might be more relaxed during the examination

Comparison of perfusion models for quantitative T1 weighted DCE-MRI of rectal cancer [Dataset]

Twenty-six patients with newly diagnosed rectal carcinoma underwent 3T MRI of the pelvis including a T1 weighted dynamic contrast enhanced (DCE) protocol before treatment. For eighteen patients, mean values for Plasma Flow (PF), Plasma Volume (PV) and Mean Transit Time (MTT) were obtained for three perfusion models

Incidence of transient interruption of contrast (TIC) – A retrospective single-centre analysis in CT pulmonary angiography exams acquired during inspiratory breath-hold with the breathing command: “Please inspire gently!”

Objectives To assess the occurrence of transient interruption of contrast (TIC) phenomenon in pulmonary computed tomography angiography (CTPA) exams performed in inspiratory breath-hold after patients were told to inspire gently. Methods In this retrospective single-centre study, CTPA exams of 225 consecutive patients scanned on a 16-slice CT scanner system were analysed. A-priori to measurements, exams were screened for inadequate pulmonary artery contrast due to incorrect bolus tracking or failure of i.v. contrast administration. Those exams were excluded. Attenuation values in the thoracic aorta and in the pulmonary trunk were assessed in duplicate measurements (M1 and M2) and the aorto-pulmonary density ratio was calculated. An aorto-pulmonary ratio > 1 with still contrast inflow being visible within the superior vena cava was defined as TIC. Results 3 patients were excluded due to incorrect bolus tracking. Final analysis was performed in 222 patients (mean age 65 ± 19 years, range 18 to 99 years). Mean density in the pulmonary trunk was 275±17 HU, in the aorta 208 ± 15 HU. Mean aorto-pulmonary ratio was 0.81± 0.29. 48 patients (21.6%) had an aorto-pulmonary ratio >1. Correlation of mean aorto-pulmonary ratio and age was: -0.213 (p = 0.001). Age was not significantly different for an aorto-pulmonary ratio >1 vs. ≤1 (p = 0.122). Both in M1 and M2, 33/222 patients presented with absolute HU values of < 200 HU within the pulmonary artery. In M1 measurements, 24 of these 33 patients (72%) fulfilled TIC criteria (M2: 25/33 patients (75%)). Conclusions TIC is a common phenomenon in CTPA studies with inspiratory breath-hold commands after patients were told to inspire gently with an incidence of 22% in our retrospective cohort. Occurrence of TIC shows a significant negative correlation with increasing age and disproportionately often occurs in patients with lower absolute contrast density values within their pulmonary arteries.ISSN:1932-620

Radiation Dose Levels of Retrospectively ECG-Gated Coronary CT Angiography Using 70-kVp Tube Voltage in Patients with High or Irregular Heart Rates

Rationale and Objectives: Despite ongoing technical refinements, coronary computed tomography angiography (cCTA) remains challenging in its diagnostic value by electrocardiographic (ECG) misregistration and motion artifacts, which commonly occur in patients with atrial fibrillation and high or irregular heart rates. The aim of this study was to evaluate the radiation dose and the number of inconclusive coronary segments at cCTA using retrospective ECG gating at 100 and 70 kV. Materials and Methods: With institutional review board approval, 154 patients (median age 54 years, 98 men) with high or irregular heart rate prospectively underwent retrospectively ECG-gated cCTA without tube current modulation on a third-generation dual-source computed tomography (DSCT) system at 70 kV (n = 103) or on a second-generation DSCT system at 100 kV (n = 51). Images were reconstructed in best diastolic phase (BDP), best systolic phase (BSP), and in all phases (APs) at 10% intervals across the R-R cycle. Objective and subjective image qualities were evaluated as well as the presence of motion artifacts with the three different reconstruction approaches. Results: The mean heart rate was 93 +/- 16 bpm. The mean effective radiation dose was 4.5 mSv for 70 kV compared to 8.4 mSv for 100 kV (P <0.05). At BDP reconstruction, 71% (n =110) of the patients showed motion artifacts in one or more coronary segments. At BSP reconstruction, the number of patients with motion artifacts decreased to 37% (n = 57). In contrast, if images were reconstructed with the AP approach, all vessels and coronary segments were evaluable with both cCTA protocols. Conclusions: Retrospectively ECG-gated cCTA at 70 kV results in 52% decreased radiation dose. Further using the AP algorithm allowed for diagnostic evaluation of all coronary segments for stenosis, in contrast to BDP or BSP phase alone

Closing in on the K Edge:Coronary CT Angiography at 100, 80, and 70 kV-Initial Comparison of a Second-versus a Third-Generation Dual-Source CT System

Purpose: To prospectively evaluate radiation and contrast medium requirements for performing high-pitch coronary computed tomographic (CT) angiography at 70 kV using a third-generation dual-source CT system in comparison to a second-generation dual-source CT system. Materials and Methods: All patients gave informed consent for this institutional review board-approved study. Forty-five patients (median age, 52 years; 27 men) were imaged in high-pitch mode with a third-generation dual-source CT system at 70 kV (n = 15) or with a second-generation dual-source CT system at 80 or 100 kV (n = 15 for each). Tube voltage was based on body mass index: 80 or 70 kV for less than 26 kg/m(2) versus 100 kV for 26-30 kg/m(2). For the 80- and 100-kV protocols, 80 mL of contrast material was injected, versus 45 mL for the 70-kV protocol. Data were reconstructed by using a second-generation iterative reconstruction algorithm for second-generation dual-source CT and a recently introduced third-generation iterative reconstruction algorithm for third-generation dual-source CT. Objective image quality was measured for various regions of interest, and subjective image quality was evaluated with a five-point Likert scale. Results: The signal-to-noise ratio of the coronary CT angiography studies acquired with 70 kV was significantly higher (70 kV: 14.3-17.6 vs 80 kV: 7.1-12.9 vs 100 kV: 9.8-12.9; P .05). The mean effective dose was 75% and 108% higher (0.92 mSv +/- 0.3 [standard deviation] and 0.78 mSv +/- 0.2 vs 0.44 mSv +/- 0.1; P <.0001), respectively, for the 80- and 100-kV CT angiography protocols than for the 70-kV CT angiography protocol. Conclusion: In nonobese patients, third-generation high-pitch coronary dual-source CT angiography at 70 kV results in robust image quality for studying the coronary arteries, at significantly reduced radiation dose (0.44 mSv) and contrast medium volume (45 mL), thus enabling substantial radiation dose and contrast medium savings as compared with second-generation dual-source CT. (C) RSNA, 201

Atherosclerotic plaque burden in cocaine users with acute chest pain:Analysis by coronary computed tomography angiography

<p>Chest pain associated with cocaine use represents an increasing problem in the emergency department (ED). Cocaine use has been linked to the acute coronary syndrome (ACS) and acute myocardial infarction (AMI). We used coronary computed tomography angiography (cCTA) to evaluate the prevalence, severity and composition of atherosclerotic lesions in cocaine users. We studied 78 patients with non-occasional cocaine use (52 men, 44 +/- 7 years, 23 under the acute influence) and acute chest pain but without ACS, who had undergone cCTA in the ED. Patients were matched one-to-one by gender, race, symptoms, and risk-factors with a control cohort (n = 78; 52 men, 45 +/- 6 years) not using cocaine. Each coronary segment was evaluated for the presence and composition (calcified, non-calcified, partially calcified) of atherosclerotic plaque and for stenosis. The prevalence of coronary stenosis was not significantly different between patients with and without cocaine use (13% versus 5%, P > 0.05). However, cocaine users on average had significantly more atherosclerotic plaques (0.44 +/- 0.88 versus 0.29 +/- 0.83, P <0.05) and a tendency towards more calcified (0.64 +/- 1.23 versus 0.55 +/- 1.22, P > 0.05) and non-calcified plaques (0.26 +/- 0.63 versus 0.17 +/- 0.57, P > 0.05), yet not reaching statistical significance. Furthermore, cocaine users had significantly more partially calcified plaques (0.41 +/- 0.61 versus 0.17 +/- 0.41, P <0.05) and higher partially calcified plaque volume (59.7 +/- 33.3 mm(3) versus 25.6 +/- 12.6 mm(3), P <0.05). Thus, cocaine users tend to have more pronounced coronary atherosclerosis compared to patients without cocaine use at the time of presentation with acute chest pain. (C) 2013 Elsevier Ireland Ltd. All rights reserved.</p>

Quantitative Analysis of Coronary Plaque Composition by Dual-Source CT in Patients with Acute Non-ST-Elevation Myocardial Infarction Compared to Patients with Stable Coronary Artery Disease Correlated with Virtual Histology Intravascular Ultrasound

<p>Rationale and Objectives: To quantitatively assess coronary atherosclerotic plaque composition in patients with acute non-ST elevation myocardial infarction (NSTEMI) and patients with stable coronary artery disease (CAD) by coronary computed tomography angiography (cCTA) correlated with virtual histology intravascular ultrasound (VH-IVUS).</p><p>Materials and Methods: Sixty patients (35 with NSTEMI) were included. Corresponding plaques were assessed by dual-source cCTA and VH-IVUS regarding volumes and percentages of fatty, fibrous, and calcified component; overall plaque burden; and maximal percent area stenosis. Possible differences between patient groups were investigated. Concordance between cCTA and VH-IVUS measurements was validated by Bland-Altman analysis.</p><p>Results: Forty corresponding plaques (22 of patients with NSTEMI) were finally analyzed by cCTA and VH-IVUS. cCTA plaque analysis revealed no significant. differences between plaques of patients with NSTEMI and stable CAD regarding absolute and relative amounts of any plaque component (fatty: 20 mm(3)/13% versus 17 mm(3)/14%; fibrous: 81 mm(3)/63% versus 80 mm(3)/53%; calcified: 16 mm(3)/14% versus 26 mm(3)126%; all P > .05) or overall plaque burden (153 mm(3) versus 165 mm(3); P > .05), nor did VH-IVUS plaque analysis. VH-IVUS measured a higher area stenosis in patients with NSTEMI compared to patients with stable CAD (76% versus 68%, P = .01; in cCTA 69% versus 65%, P = .2). Volumes of fatty component were measured systematically lower in cCTA, whereas calcified and fibrous volumes were higher. No significant bias was observed comparing volumes of overall noncalcified component and overall plaque burden.</p><p>Conclusion: Plaques of patients with acute NSTEMI and of patients with stable CAD cannot be differentiated by quantification of plaque components. cCTA and VH-IVUS differ in plaque component analysis.</p>