Optimizing Coronary Computed Tomography Angiography Using a Novel Deep Learning-Based Algorithm.

Coronary computed tomography angiography (CCTA) is an essential part of the diagnosis of chronic coronary syndrome (CCS) in patients with low-to-intermediate pre-test probability. The minimum technical requirement is 64-row multidetector CT (64-MDCT), which is still frequently used, although it is prone to motion artifacts because of its limited temporal resolution and z-coverage. In this study, we evaluate the potential of a deep-learning-based motion correction algorithm (MCA) to eliminate these motion artifacts. 124 64-MDCT-acquired CCTA examinations with at least minor motion artifacts were included. Images were reconstructed using a conventional reconstruction algorithm (CA) and a MCA. Image quality (IQ), according to a 5-point Likert score, was evaluated per-segment, per-artery, and per-patient and was correlated with potentially disturbing factors (heart rate (HR), intra-cycle HR changes, BMI, age, and sex). Comparison was done by Wilcoxon-Signed-Rank test, and correlation by Spearman's Rho. Per-patient, insufficient IQ decreased by 5.26%, and sufficient IQ increased by 9.66% with MCA. Per-artery, insufficient IQ of the right coronary artery (RCA) decreased by 18.18%, and sufficient IQ increased by 27.27%. Per-segment, insufficient IQ in segments 1 and 2 decreased by 11.51% and 24.78%, respectively, and sufficient IQ increased by 10.62% and 18.58%, respectively. Total artifacts per-artery decreased in the RCA from 3.11 ± 1.65 to 2.26 ± 1.52. HR dependence of RCA IQ decreased to intermediate correlation in images with MCA reconstruction. The applied MCA improves the IQ of 64-MDCT-acquired images and reduces the influence of HR on IQ, increasing 64-MDCT validity in the diagnosis of CCS.

[Information, informed consent, and communication with patients]. / Information, Aufklärung und Kommunikation mit den Patienten.

The transposition of EU Directive 2013/59/Euratom into German law requires that patients be informed about the radiation risk of radiological procedures. Such information is not the same as a medical informed consent about immediate risks associated with the procedure, such as deterministic radiation damage, risks of contrast media, or complications. The sole use of X­rays in diagnostic procedures therefore requires no informed consent in most cases.

Glymphatic System in Ocular Diseases: Evaluation of MRI Findings.

BACKGROUND AND PURPOSE: There is growing evidence of leakage of gadolinium in an impaired blood-retina barrier. We investigated gadolinium enhancement in different eye compartments and correlated the enhancement with specific ophthalmologic diseases. MATERIALS AND METHODS: In a prospective clinical study (ClinicalTrials.gov Identifier: NCT05035251), 95 patients (63 with and 32 without ophthalmologic disease) were examined before and after gadolinium administration (20 and 120 minutes) with heavily T2-weighted FLAIR. The cohort was divided according to the location of pathology into anterior and posterior eye compartment groups. Relative signal intensity increase in the anterior eye chamber, vitreous body with retina, optic nerve sheath, and the Meckel cave was analyzed and correlated with the final clinical diagnosis. RESULTS: In patients with a disorder in the anterior eye compartment, significant signal intensity increases were found in the central anterior eye chamber (P 20 minutes = .000, P 120 minutes = .000), lateral anterior eye chamber (P 20 minutes = .001, P 120 minutes = .005), and vitreous body with retina (P 20 minutes = .02) compared with the control group. Patients with pathologies in the posterior eye compartment showed higher signal intensity levels in the central anterior eye compartment (P 20 minutes = .041) and vitreous body with retina (P 120 minutes = .006). CONCLUSIONS: Increased gadolinium enhancement was found in the central and lateral anterior eye compartments and the vitreous body with retina in patients with anterior eye compartment disorders 20 and 120 minutes after contrast application, suggesting impairment of the blood-aqueous barrier. In patients with a disorder in the posterior eye compartment, pathologic enhancement indicated disruption of the blood-retinal barrier that allows gadolinium to diffuse into the vitreous body with retina from posterior to anterior, opposite to the known physiologic glymphatic pathway.

Corrigendum to "Improving contrast enhancement in pulmonary CTA: The value of breathing maneuvers" [Eur J Radiol Open 7 (2020) 100280].

[This corrects the article DOI: 10.1016/j.ejro.2020.100280.].

[Current diagnostic imaging and treatment planning for laryngeal cancer]. / Aktuelle Bildgebung bei Diagnostik und Therapieplanung des Larynxkarzinoms.

CLINICAL/METHODICAL ISSUE: Laryngeal cancer is the third most common malignancy in the head and neck region. Endoscopic laryngoscopy with assessment of vocal fold function, microlaryngoscopy with biopsy and computed tomography (CT)/magnetic resonance imaging (MRI) remain the cornerstones of diagnostic workup. Thus, in the context of therapy planning, consideration of individual functional and socioeconomic aspects is of major importance. STANDARD RADIOLOGICAL METHODS: Due to the short acquisition time and the possibility to perform functional maneuvers, CT is the tool of choice. MRI allows better soft tissue differentiation, but is more susceptible to movement artifacts and is complicated by disease-specific symptoms. The choice of examination method therefore depends on the patient's physical resilience. PERFORMANCE: Depending on the study, the information on the sensitivity of CT with regard to the question of cartilage infiltration varies between 62 and 87% with a specificity between 75 and 98%. For MRI, sensitivity between 64 and 95% and specificity between 56 and 88% are stated. ACHIEVEMENTS: The synthesis of the findings from endoscopy, biopsy and imaging is prerequisite for initiation of stage-appropriate treatment. For image interpretation, knowledge of the anatomical landmarks is essential. However, the assessment of posttherapeutic changes also poses a challenge for the radiologist. PRACTICAL RECOMMENDATIONS: Regular interdisciplinary dialogue between radiologists, otorhinolaryngologists and radiotherapists in the context of primary diagnostics, therapy planning and aftercare is essential.

Improving Contrast Enhancement in Pulmonary CTA: The value of breathing maneuvers.

PURPOSE: To investigate contrast dynamics and artifacts associated with different breathing maneuvers during pulmonary computed tomography angiography (pCTA) in a prospective randomized clinical trial. METHOD: Three different breathing maneuvers (inspiration, expiration, Mueller) were randomly assigned to 146 patients receiving pCTA for suspected pulmonary embolism (PE). Contrast enhancement of central and peripheral arteries and imaging quality of lung parenchyma were compared and analyzed. Results were compared by using the analysis of variances (ANOVA) and Kruskal-Wallis-Test. RESULTS: Mean enhancement in the pulmonary trunk was highest during breath-hold in inspiration (293 HU, range 195-460 HU) compared to Mueller (259 HU, range 136-429 HU, p = 0022) and expiration (267 HU, range 115-376 HU). This was similar for the right pulmonary artery (inspiration 289 HU, range 173-454 HU; Mueller 250 HU, range 119-378 HU; p = 0.007; expiration 257 HU, range 114-366 HU; p = 0.032) and left pulmonary artery (inspiration 280.3 HU, range 170-462 HU; Mueller 245 HU, range 111-371 HU; p = 0.016; expiration 252 HU, range 110-371 HU).Delineation of peripheral arteries was significantly better in inspiration vs Mueller (p = 0.006) and expiration (p = 0.049). Assessment of the lung parenchyma was significantly better in inspiration vs Mueller (p = 0.013) or expiration (p < 0.001). CONCLUSIONS: Resting inspiratory position achieved the highest enhancement levels in central and peripheral pulmonary arteries and best image quality of the pulmonary parenchyma in comparison to other breathing maneuvers. It is necessary to train the maneuver prior to the examination in order to avoid deep inspiration with the risk of suboptimal opacification of the pulmonary arteries.

Microcystic adnexal carcinoma (MAC)-like squamous cell carcinoma as a differential diagnosis to Bell´s palsy: review of guidelines for refractory facial nerve palsy.

BACKGROUND: Bell´s palsy is the most common cause of facial paralysis worldwide and the most common disorder of the cranial nerves. It is a diagnosis of exclusion, accounting for 60-75% of all acquired peripheral facial nerve palsies. Our case shows the first case of a microcystic adnexal carcinoma-like squamous cell carcinoma as a cause of facial nerve palsy. CASE PRESENTATION: The patient, a 70-year-old Caucasian male, experienced subsequent functional impairment of the trigeminal and the glossopharyngeal nerve about 1½ years after refractory facial nerve palsy. An extensive clinical work-up and tissue biopsy of the surrounding parotid gland tissue was not able to determine the cause of the paralysis. Primary infiltration of the facial nerve with subsequent spreading to the trigeminal and glossopharyngeal nerve via neuroanastomoses was suspected. After discussing options with the patient, the main stem of the facial nerve was resected to ascertain the diagnosis of MAC-like squamous cell carcinoma, and radiochemotherapy was subsequently started. CONCLUSION: This case report shows that even rare neoplastic etiologies should be considered as a cause of refractory facial nerve palsy and that it is necessary to perform an extended diagnostic work-up to ascertain the diagnosis. This includes high-resolution MRI imaging and, as perilesional parotid biopsies might be inadequate for rare cases like ours, consideration of a direct nerve biopsy to establish the right diagnosis.

[Imaging of the head and neck region]. / Bildgebung der Kopf-Hals-Region.

Tumors of the head and neck are predominantly squamous cell carcinomas and those of the salivary glands are predominantly adenocarcinomas, adenoid cystic carcinomas and mucoepidermoid carcinomas. In 2011 the incidence of tumors of the oral cavity and pharynx in Germany was 6839 (5026 male and 1813 female) and of the larynx 1878 (1642 male and 236 female). The incidence of tumors of the nose and paranasal sinuses (467) and salivary glands (470) were much lower (www.krebsdaten.de/abfrage). The primary aim of imaging in head and neck cancer is staging of the disease and a precise assessment of tumor invasion. This information is essential for therapy decision-making (i. e. surgery or radiochemotherapy), planning of the extent of resection and subsequent reconstructive measures and also estimation of functional deficits after therapy. Computed tomography (CT) and magnetic resonance imaging (MRI) are the imaging modalities of choice but both have specific advantages and disadvantages. In certain cases both CT and MRI need to be performed for accurate treatment planning.

[Imaging of the head and neck region]. / Bildgebung der Kopf-Hals-Region.

Tumors of the head and neck are predominantly squamous cell carcinomas and those of the salivary glands are predominantly adenocarcinomas, adenoid cystic carcinomas and mucoepidermoid carcinomas. In 2011 the incidence of tumors of the oral cavity and pharynx in Germany was 6839 (5026 male and 1813 female) and of the larynx 1878 (1642 male and 236 female). The incidence of tumors of the nose and paranasal sinuses (467) and salivary glands (470) were much lower ( www.krebsdaten.de/abfrage ). The primary aim of imaging in head and neck cancer is staging of the disease and a precise assessment of tumor invasion. This information is essential for therapy decision-making (i. e. surgery or radiochemotherapy), planning of the extent of resection and subsequent reconstructive measures and also estimation of functional deficits after therapy. Computed tomography (CT) and magnetic resonance imaging (MRI) are the imaging modalities of choice but both have specific advantages and disadvantages. In certain cases both CT and MRI need to be performed for accurate treatment planning.

Cardiac MRI in Children and Adolescents Who Have Undergone Surgical Repair of Right-Sided Congenital Heart Disease: Automated Left Ventricular Volumes and Function Analysis and Effects of Different Manual Adjustments.

PURPOSE: To evaluate automated segmentation and the effects of different manual adjustments regarding left ventricular parameter quantification in cardiac magnetic resonance (MR) data on children and adolescents who have undergone surgical repair of right-sided congenital heart disease (CHD). MATERIALS AND METHODS: Dedicated software (syngo.via, Siemens AG) was used to automatically segment and/or manually adjust the end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), myocardial mass (MM) and ejection fraction (EF) before/after manual apex/base adjustment (ADJ-step 1) and after manual apex/base/myocardial contour adjustment (ADJ-step 2; reference standard). MR data of 40 patients (13.1 ± 3. y, 4 - 17 y) with repaired CHD with decreased pulmonary blood flow (CHD-DPBF) were evaluated. Intra- and inter-rater reliability was determined for 10 randomly selected patients. RESULTS: The software correctly detected the left ventricle in 38/40 (95%) patients. EDV after automated segmentation: 119.1 ± 44.0 ml; after ADJ-step 1: 115.8 ± 9.5 ml; after ADJ-step 2: 116.2 ± 39.4 ml. The corresponding results for ESV were 52.0 ± 18.5/49.6 ± 6.9/49.7 ± 16.4 ml; for SV 67.1 ± 28.5/66.2 ± 25.4/66.5 ± 25. ml; for EF 55.5 ± 7.3/56.7 ± 6.6/56.7 ± 6.3%; for MM 83.7 ± 35.9/76.2 ± 8.3/74.6 ± 27.2 g. Significant differences were found for ESV/MM/EF comparing the automated segmentation results with these after ADJ-step 1 and ADJ-step 2. No significant differences were found when comparing all results of ADJ-step 1 and ADJ-step 2 or when comparing EDV/SV results. Intra- and inter-rater reliability was excellent. The mean time effort was 63.4 ± 6.9 s for the automated segmentation, 74.2 ± 8.9 s for ADJ-step 1 and 269.5 ± 39.4 s for ADJ-step 2. CONCLUSION: Automated left ventricular volumes and function analysis in children and adolescents with surgically treated CHD proved to be feasible with excellent intra- and inter-rater reliability. Automated segmentation with manual apex/base adjustment provided clinically acceptable results. KEY POINTS: Automated left ventricular volume and function analysis in children and adolescents with surgically treated right-sided heart disease is feasible with excellent intra- and inter-rater reliability. Automated segmentation with manual apex/base adjustment provides clinically acceptable results. Additional manual myocardial contour adjustment does not significantly improve the results.

Improved Image Quality in Head and Neck CT Using a 3D Iterative Approach to Reduce Metal Artifact.

BACKGROUND AND PURPOSE: Metal artifacts from dental fillings and other devices degrade image quality and may compromise the detection and evaluation of lesions in the oral cavity and oropharynx by CT. The aim of this study was to evaluate the effect of iterative metal artifact reduction on CT of the oral cavity and oropharynx. MATERIALS AND METHODS: Data from 50 consecutive patients with metal artifacts from dental hardware were reconstructed with standard filtered back-projection, linear interpolation metal artifact reduction (LIMAR), and iterative metal artifact reduction. The image quality of sections that contained metal was analyzed for the severity of artifacts and diagnostic value. RESULTS: A total of 455 sections (mean ± standard deviation, 9.1 ± 4.1 sections per patient) contained metal and were evaluated with each reconstruction method. Sections without metal were not affected by the algorithms and demonstrated image quality identical to each other. Of these sections, 38% were considered nondiagnostic with filtered back-projection, 31% with LIMAR, and only 7% with iterative metal artifact reduction. Thirty-three percent of the sections had poor image quality with filtered back-projection, 46% with LIMAR, and 10% with iterative metal artifact reduction. Thirteen percent of the sections with filtered back-projection, 17% with LIMAR, and 22% with iterative metal artifact reduction were of moderate image quality, 16% of the sections with filtered back-projection, 5% with LIMAR, and 30% with iterative metal artifact reduction were of good image quality, and 1% of the sections with LIMAR and 31% with iterative metal artifact reduction were of excellent image quality. CONCLUSIONS: Iterative metal artifact reduction yields the highest image quality in comparison with filtered back-projection and linear interpolation metal artifact reduction in patients with metal hardware in the head and neck area.

Thoracic non-osseous lesions in cancer patients detected in low-dose CT images acquired as part of skeletal SPECT/CT examinations.

AIM: Hybrid single-photon emission tomographic (SPECT) and X-ray computed tomography (CT) systems are increasingly used in oncologic imaging. With SPECT/CT not only the thoracic spine but also the surrounding soft tissue needs to be evaluated for pathological findings. The purpose of this study was to assess the prevalence of non-osseous findings detectable on low-dose CT datasets from patients studied by thoracic 99mTc-dicarboxypropane diphosphonate (DPD)-SPECT/CT. PATIENTS, METHODS: 119 consecutive oncologic patients (81 breast cancer, 38 with other cancer) who underwent DPD-SPECT CT of the thoracic region were included in this study. Non-osseous findings on CT were classified as either probably benign or suspicious. Suspicious findings were correlated with retrievable previous imaging and if performed with follow up imaging (MRI, CT with contrast medium, Ultrasound) or biopsy results. RESULTS: In 80/119 (67%) patients no imaging was performed before SPECT/CT. Only 7/119 subjects (6%) had no other lesions than bone lesions. In 101/119 (85%) patients lesions found on SPECT/CT images were rated as benign and in 65/119 (55%) patients as suspicious. In 8/119 (7%) patients with previously unknown suspicious lesions on SPECT/CT images suspicious findings were confirmed by biopsy. CONCLUSION: 7% of patients referred to SPECT/CT of the thoracic spine for staging of malignant disease had previously unknown suspicious non-osseous lesions detectable on the low-dose CT images which were confirmed by biopsy. This could be especially relevant for cancer entities like breast and prostate, in which no thorax-CT is routinely intended for staging.

Imaging the Parasinus Region with a Third-Generation Dual-Source CT and the Effect of Tin Filtration on Image Quality and Radiation Dose.

BACKGROUND AND PURPOSE: CT is the imaging technique of choice in the evaluation of midface trauma or inflammatory disease. We performed a systematic evaluation of scan protocols to optimize image quality and radiation exposure on third-generation dual-source CT. MATERIALS AND METHODS: CT protocols with different tube voltage (70-150 kV), current (25-300 reference mAs), prefiltration, pitch value, and rotation time were systematically evaluated. All images were reconstructed with iterative reconstruction (Advanced Modeled Iterative Reconstruction, level 2). To individually compare results with otherwise identical factors, we obtained all scans on a frozen human head. Conebeam CT was performed for image quality and dose comparison with multidetector row CT. Delineation of important anatomic structures and incidental pathologic conditions in the cadaver head was evaluated. RESULTS: One hundred kilovolts with tin prefiltration demonstrated the best compromise between dose and image quality. The most dose-effective combination for trauma imaging was Sn100 kV/250 mAs (volume CT dose index, 2.02 mGy), and for preoperative sinus surgery planning, Sn100 kV/150 mAs (volume CT dose index, 1.22 mGy). "Sn" indicates an additional prefiltration of the x-ray beam with a tin filter to constrict the energy spectrum. Exclusion of sinonasal disease was possible with even a lower dose by using Sn100 kV/25 mAs (volume CT dose index, 0.2 mGy). CONCLUSIONS: High image quality at very low dose levels can be achieved by using a Sn100-kV protocol with iterative reconstruction. The effective dose is comparable with that of conventional radiography, and the high image quality at even lower radiation exposure favors multidetector row CT over conebeam CT.

[High versus moderate intense running exercise - effects on cardiometabolic risk-factors in untrained males]. / Hoch- versus moderat-intensive Laufbelastung - Einfluss auf kardio-metabolische Risikogrößen bei untrainierten Männern.

Introduction | The philosophy on how to improve cardiometabolic risk factors most efficiently by endurance exercise is still controversial. To determine the effect of high-intensity (interval) training (HI[I]T) vs. moderate-intensity continuous exercise (MICE) training on cardiometabolic risk factors we conducted a 16-week crossover randomized controlled trial. Methods | 81 healthy untrained middle aged men were randomly assigned to a HI(I)T-group and a control-group that started the MICE running program after their control status. HI(I)T consisted of running exercise around or above the individual anaerobic threshold (≈ 80- 100 % HRmax); MICE focused on continuous running exercise at ≈ 65-77.5 % HRmax. Both protocols were comparable with respect to energy consumption. Study endpoints were cardiorespiratory fitness (VO2max), left ventricular mass index (LVMI), metabolic syndrome Z-score (MetS-Z-score), intima-media-thickness (IMT) and body composition. Results | VO2max-changes in this overweighed male cohort significantly (p=0.002) differ between HIIT (14.7 ± 9.3 %, p=0.001) and MICE (7.9 ± 7.4 %,p=0.001). LVMI, as determined via magnetic resonance imaging, significantly increased in both exercise groups (HIIT: 8.5 ± 5.4 %, p=0.001 vs. MICE: 5.3 ± 4.0 %, p=0.001), however the change was significantly more pronounced (p=0.005) in the HIIT-group. MetS-Z-score (HIIT: -2.06 ± 1.31, p=0.001 vs. MICE: -1.60 ± 1.77, p=0.001) and IMT (4.6 ± 5.9 % p=0.011 vs. 4.4 ± 8.1 %, p=0.019) did not show significant group-differences. Reductions of fat mass (-4.9 ± 9.0 %, p=0.010 vs. -9.5 ± 9.4, p=0.001) were significantly higher among the MICE-participants (p=0.034), however, the same was true (p=0.008) for lean body mass (0.5 ± 2.3 %, p=0.381 vs. -1.3 ± 2.0 %, p=0.003). Conclusion | In summary high-intensity interval training tends to impact cardiometabolic health more favorable compared with a moderate-intensity continuous endurance exercise protocol.

Cone beam computed tomography and low-dose multislice computed tomography in orthodontics and dentistry: a comparative evaluation on image quality and radiation exposure.

OBJECTIVES: The goal of the present work was to assess various computed tomography (CT) systems in term of image quality and organ doses, namely five cone-beam CT (CBCT) scanners operated at standard settings and three multislice CT (MSCT) scanners operated at greatly dose-reduced settings. MATERIALS AND METHODS: Radiographic volume scans were taken on a complete human cadaveric head specimen and the image quality of each was rated by four experienced examiners according to specific skeletal structures and bone-soft tissue interfaces. Radiation doses were captured by a head-and-neck phantom (Rando; Alderson Research Laboratories). Standard protocols were used for the CBCT scans. For the MSCT scans, tube voltage and current were adjusted to minimize radiation without compromising image quality. RESULTS: Interobserver agreement was close to perfect, with iota coefficients of 0.931 (95% CI 0.807-0.978) between groups 1 and 2 and 0.959 (95% CI 0.869-1.000) between groups 1 and 3. Ratings of image quality in terms of skeletal-structure representation were slightly better for the CBCT than the MSCT scanners, although these differences were not statistically significant. The two groups of scanners applied considerably different organ doses: the lowest dose (0.03 mSv) was measured on the bone surface with a CBCT unit (Picasso Trio® from Vatech) and the highest dose (8.30 mSv) in the vicinity of the eye lens with another CBCT unit (3D Accuitomo 170® from J. Morita). CONCLUSION: The various systems tested offer similar imaging quality but demonstrated distinct differences in organ dose levels. The decision on which approach to take is not between CBCT and MSCT but rather between specific models and parameter settings. If these are optimized, MSCT images providing useful clinical information can be obtained at much reduced levels of radiation. Depending on the model and setting used, MSCT radiation levels may even be lower than during CBCT scans.

Interobserver variability of CT angiography for evaluation of aortic annulus dimensions prior to transcatheter aortic valve implantation (TAVI).

OBJECTIVE: Assessment of aortic annulus dimensions prior to transcatheter aortic valve implantation (TAVI) is crucial for accurate prosthesis sizing in order to avoid prosthesis-annulus-mismatch possibly resulting in complications like valve dislodgement, paravalvular regurgitation or annulus rupture. Contrast-enhanced multidetector computed tomography allows 3-dimensional assessment of aortic annulus dimensions. Only limited data exist about its interobserver variability. METHODS: In 100 consecutive patients with symptomatic severe aortic stenosis (51 male, BMI 27±5kg/m(2), age 81±7 years, heart rate 72±15bpm, Logistic Euroscore 31±14%, STS-Score 7±4%), pre-interventional aortic annulus assessment was performed by dual source computed tomography (collimation 2×128×0.6mm, high pitch spiral data acquisition mode, 40-60ml contrast agents, radiation dose 3.5±0.9mSv). The following aortic annulus characteristics were determined by three independent observers: aortic annulus maximum, minimum and mean diameters (Dmax, Dmin, Dmean), eccentricity index (EI), effective aortic annulus diameter according to its circumference (Dcirc), effective aortic annulus diameter according to its area (Darea), distance from the aortic annulus plane to the left (LCA) and right coronary artery (RCA) ostia, maximum (DmaxAR) and minimum aortic root diameter (DminAR), maximum (DmaxSTJ) and minimum diameter of the sinotubular junction (DminSTJ). Subsequently, interobserver variabilities were assessed. RESULTS: Correlation between the three observers showed moderate to close agreement (between r=0.67 and r=0.97, all p<0.001). Mean differences (SE) between the three observers ranged from 0.07 (0.06)mm to 0.24 (0.07)mm for assessing the mean AA diameter (Dmean), from 0.28 (0.04)mm to 0.60 (0.06)mm for determining the effective AA diameter derived from the annulus area (Darea) and from 0.03 (0.07)mm to 0.07 (0.11)mm derived from the AA perimeter (Dcirc). For measurements of LCA and RCA distances to the AA level, mean interobserver differences (SE) ranged from 0.36 (0.07)mm to 0.76 (0.09)mm and from 0.15 (0.06)mm to 0.45 (0.11)mm. CONCLUSION: Computed tomography provides reproducible measurements of the aortic annulus and root geometry in patients scheduled for TAVI. The perimeter-derived aortic annulus diameter shows the lowest interobserver differences. Interobserver variabilities in prosthesis size recommendation were further reduced, if all three sizing methods were considered and stated as a "consensus result".

Dose reduction in computed tomography of the chest: image quality of iterative reconstructions at a 50% radiation dose compared to filtered back projection at a 100% radiation dose.

PURPOSE: The aim of this study was to evaluate the potential of iterative reconstruction (IR) in chest computed tomography (CT) to reduce radiation exposure. The qualitative and quantitative image quality of standard reconstructions with filtered back projection (FBP) and half dose (HD) chest CT data reconstructed with FBP and IR was assessed. MATERIALS AND METHODS: 52 consecutive patients underwent contrast-enhanced chest CT on a dual-source CT system at 120 kV and automatic exposure control. The tube current was equally split on both tube detector systems. For the HD datasets, only data from one tube detector system was utilized. Thus, FD and HD data was available for each patient with a single scan. Three datasets were reconstructed from the raw data: standard full dose (FD) images applying FBP which served as a reference, HD images applying FBP and IR. Objective image quality analysis was performed by measuring the image noise in tissue and air. The subjective image quality was evaluated by 2 radiologists according to European guidelines. Additional assessment of artifacts, lesion conspicuity and edge sharpness was performed. RESULTS: Image noise did not differ significantly between HD-IR and FD-FBP (p = 0.254) but increased substantially in HD-FBP (p < 0.001). No statistically significant differences were found for the reproduction of anatomical and pathological structures between HD-IR and FD-FBP, subsegmental bronchi and bronchioli. The image quality of HD-FBP was rated inferior because of increased noise. CONCLUSION: A 50 % dose reduction in contrast-enhanced chest CT is feasible without a loss of diagnostic confidence if IR is used for image data reconstruction. Iterative reconstruction is another powerful tool to reduce radiation exposure and can be combined with other dose-saving techniques. KEY POINTS: • Iterative reconstructions allow for image noise and artifact reduction.• Comparable image data can thus be attained even at 50 % radiation dose.• Diagnostic confidence remains unaffected.

Carotid CTA: radiation exposure and image quality with the use of attenuation-based, automated kilovolt selection.

BACKGROUND AND PURPOSE: CTA is considered the imaging modality of choice in evaluating the supraaortic vessels in many institutions, but radiation exposure remains a matter of concern. The objective of the study was to evaluate a fully automated, attenuation-based kilovolt selection algorithm in carotid CTA in respect to radiation dose and image quality compared with a standard 120-kV protocol. MATERIALS AND METHODS: Ninety-eight patients were included: 53 examinations (patient age, 66 ± 12 years) were performed by use of automated adaption of tube potential (80-140 kV) on the basis of the attenuation profile of the scout scan (study group), and 45 examinations (patient age, 67 ± 11 years) were performed by use of a standard 120-kV protocol (control group). CT dose index volume and dose-length product were recorded from the examination protocol. Image quality was assessed by ROI measurements and calculations of SNR and contrast-to-noise ratio. Subjective image quality was evaluated by 2 observers with the use of a 4-point scale (3, excellent; 0, not diagnostic). RESULTS: Subjective image quality was rated as "excellent" or "good" in all examinations (study group, 2.8; control group, 2.8). The algorithm automatically selected 100 kV in 47% and 80 kV in 34%; 120 kV was retained in 19%. An elevation to 140 kV did not occur. Compared with the control group, overall CT dose index volume reduction was 33.7%; overall dose-length product reduction was 31.5%. In the low-kilovolt scans, image noise and mean attenuation of ROIs inside the carotid arteries were significantly higher than in 120-kV scans, resulting in a constant or increased (80-kV group) contrast-to-noise ratio. CONCLUSIONS: The attenuation-based, kilovolt selection algorithm enables a dose reduction of >30% in carotid artery CTA while maintaining contrast-to-noise ratio and subjective image quality at adequate levels.