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Objectives: To evaluate computed tomography fractional flow reserve (FFR CT ) values in distal parts of the coronaries in an asymptomatic cohort of marathon runners without any coronary stenosis for potentially false-positive values., Methods: Ninety-eight asymptomatic male marathon runners (age 53 ± 7 years) were enrolled in a prospective monocentric study and underwent coronary computed tomography angiography (CCTA). CCTA data were analyzed for visual coronary artery stenosis. FFR CT was evaluated in 59 participants without coronary artery stenosis in proximal, mid, and distal coronary sections using an on-site software prototype., Results: In participants without coronary artery stenosis, abnormal FFR CT values ≤ 0.8 in distal segments were found in 22 participants (37%); in 19 participants in the LAD; in 5 participants in the LCX; and in 4 participants in the RCA. Vessel diameters in participants with FFR CT values > 0.80 compared to ≤ 0.80 were 1.6 ± 0.3 mm versus 1.5 ± 0.3 mm for distal LAD (p = 0.025), 1.8 ± 0.3 mm versus 1.6 ± 0.5 mm for distal LCX (p = 0.183), and 2.0 ± 0.4 mm versus 1.5 ± 0.2 mm for distal RCA (p < 0.001)., Conclusions: Abnormal FFR CT values of ≤ 0.8 frequently occurred in distal coronary segments in subjects without any anatomical coronary artery stenosis. This effect is only to some degree explainable by small distal vessel diameters. Therefore, the validity of hemodynamic relevance evaluation using FFR CT in distal coronary artery segment stenosis is reduced., Key Points: • Abnormal FFR CT values (≤ 0.8) occurred in over a third of the subjects in the distal LAD despite the absence of coronary artery stenosis.. • Therefore, the validity of hemodynamic relevance evaluation in distal coronary artery segment stenosis is reduced. • Decision-making based on abnormal FFR CT values in distal vessel sections should be performed with caution and only in combination with visual assessment of the grade of stenosis.., (© 2021. The Author(s).)

Objectives: Computed tomography (CT) imaging of the clavicula displays the reference standard for forensic bone age diagnostics in adolescents and young adults. Consequently, highest efforts on radiation reduction are warranted. Therefore, the aim of this study was to investigate the feasibility of low-dose (LD) CT imaging of the clavicula for age estimation in living adolescents., Methods: A total of 207 non-contrast chest CT of 144 patients born between 1988 and 2012, performed in 2018 due to various clinical indications, were included in this retrospective study. The mean patient age was 16.9 ± 6.6 years. Patients were divided into a LD (n = 146) and standard-dose (SD; n = 61) group. Image quality, confidence levels, and ossification stages (using the 5-stage classification including the subgroups 2a-3c) were assessed by two radiologists independently. Radiation dose was determined via dosimetry software., Results: Dose simulation with z-axis reduction to depict the clavicula only resulted in a median exposure of 0.1 mSv (IQR: 0.0) in LD compared with 0.9 mSv (IQR: 0.6) in SD (p < 0.001). The median image quality was rated by both readers significantly worse in LD compared with SD on a Likert scale ranging from 1 to 4 with a median of 3 (IQR: 1) versus 4 (IQR: 0; p < 0.001 for both readers). There was an almost perfect agreement for the ossification stages between both readers with a Cohen's kappa of 0.83 (p < 0.001). Median confidence levels of both readers were not significantly different between LD and SD in the decisive subgroups 2a-3c., Conclusions: Low-dose CT imaging of the clavicula for age estimation in living adolescents is possible without loss of readers' confidence., Key Points: • Radiological bone age diagnostics in young delinquents with unknown exact chronological age is important as the judicial systems differentiate between youths and adults. • Low-dose computed tomography scanning of the medial clavicular joint for forensic age estimation is feasible in living adolescents without loss of readers' confidence. • Sufficient image quality of the medial clavicular joint for forensic bone age diagnostics in living adolescents is achievable using a median dose of 0.1 mSv.

Objectives: Magnetic resonance imaging (MRI) aids diagnosis in cystic fibrosis (CF) but its use in quantitative severity assessment is under research. This study aims to assess changes in signal intensity (SI) and lung volumes (Vol) during functional MRI and their use as a severity assessment tool in CF patients., Methods: The CF intra-hospital standard chest 1.5 T MRI protocol comprises of very short echo-time sequences in submaximal in- and expiration for functional information. Quantitative measurements (Vol/SI at in- and expiration, relative differences (Vol&#95;delta/SI&#95;delta), and cumulative histograms for normalized SI values across the expiratory lung volume) were assessed for correlation to pulmonary function: lung clearance index (LCI) and forced expiratory volume in 1 s (FEV 1 )., Results: In 49 patients (26 male, mean age 17 ± 7 years) significant correlation of Vol&#95;delta and SI&#95;delta (R = 0.86; p < 0.0001) during respiration was observed. Individual cumulated histograms enabled severity disease differentiation (mild, severe) to be visualized (defined by functional parameter: LCI > 10). The expiratory volume at a relative SI of 100% correlated significantly to LCI (R = 0.676 and 0.627; p < 0.0001) and FEV 1 (R = - 0.847 and - 0.807; p < 0.0001). Clustering patients according to Vol&#95;SI&#95;100 showed that an amount of ≤ 4% was related to normal, while an amount of > 4% was associated with pathological pulmonary function values., Conclusion: Functional pulmonary MRI provides a radiation-free severity assessment tool and can contribute to early detection of lung impairment in CF. Lung volume with SI below 100% of the inspiratory volume represents overinflated tissue; an amount of 4% of the expiratory lung volume was a relevant turning point., Key Points: • Signal intensity and lung volumes are used as potential metric parameters for lung impairment. • Quantification of trapped air impacts on therapy management. • Functional pulmonary MRI can contribute to early detection of lung impairment.

Objectives: To evaluate the applicability of a semiquantitative MRI scoring system (MR-CF-S) as a prognostic marker for clinical course of cystic fibrosis (CF) lung disease., Methods: This observational study of a single-centre CF cohort included a group of 61 patients (mean age 12.9 ± 4.7 years) receiving morphological and functional pulmonary MRI, pulmonary function testing (PFT) and follow-up of 2 years. MRI was analysed by three raters using MR-CF-S. The inter-rater agreement, correlation of score categories with forced expiratory volume in 1 s (FEV 1 ) at baseline, and the predictive value of clinical parameters, and score categories was assessed for the whole cohort and a subgroup of 40 patients with moderately impaired lung function., Results: The inter-rater agreement of MR-CF-S was sufficient (mean intraclass correlation coefficient 0.92). MR-CF-S (-0.62; p < 0.05) and most of the categories significantly correlated with FEV 1 . Differences between patients with relevant loss of FEV 1 (>3%/year) and normal course were only significant for MR-CF-S (p < 0.05) but not for clinical parameters. Centrilobular opacity (CO) was the most promising score category for prediction of a decline of FEV 1 (area under curve: whole cohort 0.69; subgroup 0.86)., Conclusions: MR-CF-S is promising to predict a loss of lung function. CO seems to be a particular finding in CF patients with an abnormal course., Key Points: • Lung imaging is essential in the diagnostic work-up of CF patients • MRI serves as a powerful, radiation-free modality in paediatric CF patients • Observational single-centre study showed significant correlation of MR-CF score and FEV 1 • MR-CF score is promising in predicting a loss of lung function.

Purpose: The superior thyroid cornu (STC) of the thyroid cartilage is a variable structure that maybe associated with different clinical symptoms. This study evaluates the three-dimensional anatomy of the STC., Methods: Measurements were conducted on 97 CT scans (45 male and 52 female). The protocol models a vector from the base to the tip of the STC and references the cornu to the midline. From these data, the length (C), the rotation angle (γ), the inclination angle (β), and the deviation of STC base (X 2 ) and tip (X 3 ) from the midline were measured. An additional measure of the medial inclination quotient (Q = X 3 /X 2 ) was calculated., Results: The STC has a mean length of 13.9 ± 3.26 mm. The male STC is more bent inwards (rotation angle (γ) 60.95° vs. 12.15°; p < 0.001), and the female STC is more steep (inclination angle (β) 75.44° vs. 73.44°; p < 0.001). The mean Q in men was significantly lower (0.85 ± 0.15 vs. 0.97 ± 0.15; p < 0.001). An extreme medial deformation was found in 13.4 % of the patients. This variation is associated with Q ≤ 0.7, most of the time unilateral and more common in men (86.7 vs. 13.3 %). Furthermore, we can describe STC variations with close proximity to the common carotid artery or the cervical spine., Conclusions: The clinically most relevant variation of the STC seems to be the extreme medial deviation, which may lead to symptoms described with the superior thyroid cornu syndrome. The evaluation of Q in axial CT scans is easily done and may propose a helpful tool for clinical diagnostics.

Objectives: To assess dose area products (DAP) and effective doses (ED) of voiding cystourethrography (VCUG) in children using optimized protocols on a modern flat detector unit., Methods: DAP and ED were evaluated in 651 VCUG (316 girls, median age: 2.25 years) between 2009 and 2012. DAP was analyzed in relation to patient characteristics (gender, age, presence of pathological findings) and experience of performing physician using analysis of variance. ED values were estimated using adapted conversion factors from the literature. Diagnostic image quality was validated by two experienced physicians using a 3-point scale., Results: Median DAP/ED was 0.5 cGycm(2)/4.56 μSv (boys: 0.6 cGycm(2)/6.16 μSv; girls: 0.4 cGycm(2)/3.54 μSv). In 300 studies without pathologic findings DAP was 0.35 cGycm(2), whereas 351 studies with pathologic findings had a median DAP of 0.7 cGycm(2). No significant relationship between DAP and experience of radiologist was observed. Image validation resulted in an overall good to excellent rating., Conclusions: DAP and ED can be markedly reduced in paediatric VCUG performed with optimized protocols on modern equipment without a noticeable decrease in diagnostic image quality., Key Points: • Voiding cystourethrography is a comprehensive examination in diagnosing vesicoureteral reflux (VUR). • Radiation reduction is achieved in VCUG through modern equipment and optimized protocols. • Low-dose VCUG is possible without noticeable decrease in diagnostic image quality.

Aims and Objectives: Deep venous thrombosis (DVT) can be difficult to detect using CT due to poor and heterogeneous contrast. Dual-energy CT (DECT) allows iodine contrast optimization using noise-optimized monoenergetic extrapolations (MEIs) and iodine maps (IMs). Our aim was to assess whether MEI and IM could improve the delineation of thrombotic material within iodine-enhanced blood compared to single-energy CT (SECT)., Materials and Methods: Six vessel phantoms, including human thrombus and contrast media-enhanced blood and one phantom without contrast, were placed in an attenuation phantom and scanned with DECT 100/140 kV and SECT 120 kV. IM, virtual non-contrast images (VNC), mixed images, and MEI were calculated. Attenuation of thrombi and blood were measured. Contrast and contrast-to-noise-ratios (CNRs) were calculated and compared among IM, VNC, mixed images, MEI, and SECT using paired t tests., Results: MEI40keV and IM showed significantly higher contrast and CNR than SE120kV from high to intermediate iodine concentrations (contrast:pMEI40keV < 0.002,pIM < 0.005;CNR:pMEI40keV < 0.002,pIM < 0.004). At low iodine concentrations, MEI190keV and VNC images showed significantly higher contrast and CNR than SE120kV with inverted contrasts (contrast:pMEI190keV < 0.008,pVNC < 0.002;CNR:pMEI190keV < 0.003,pVNC < 0.002)., Conclusions: Noise-optimized MEI and IM provide significantly higher contrast and CNR in the delineation of thrombosis compared to SECT, which may facilitate the detection of DVT in difficult cases., Key Points: • Poor contrast makes it difficult to detect thrombosis in CT. • Dual-energy-CT allows contrast optimization using monoenergetic extrapolations (MEI) and iodine maps (IM). • Noise-optimized-MEI and IM are significantly superior to single-energy-CT in delineation of thrombosis. • Noise-optimized-MEI and IM may facilitate the detection of deep vein thrombosis.

The efficiency and radiation dose of a low-dose dual-energy (DE) CT protocol for the evaluation of urinary calculus disease were evaluated. A low-dose dual-source DE-CT renal calculi protocol (140 kV, 46 mAs; 80 kV, 210 mAs) was derived from the single-energy (SE) CT protocol used in our institution for the detection of renal calculi (120 kV, 75 mAs). An Alderson-Rando phantom was equipped with thermoluminescence dosimeters and examined by CT with both protocols. The effective doses were calculated. Fifty-one patients with suspected or known urinary calculus disease underwent DE-CT. DE analysis was performed if calculi were detected using a dedicated software tool. Results were compared to chemical analysis after invasive calculus extraction. An effective dose of 3.43 mSv (male) and 5.30 mSv (female) was measured in the phantom for the DE protocol (vs. 3.17/4.57 mSv for the SE protocol). Urinary calculi were found in 34 patients; in 28 patients, calculi were removed and analyzed (23 patients with calcified calculi, three with uric acid calculi, one with 2,8-dihyxdroxyadenine-calculi, one patient with a mixed struvite calculus). DE analysis was able to distinguish between calcified and non-calcified calculi in all cases. In conclusion, dual-energy urinary calculus analysis is effective also with a low-dose protocol. The protocol tested in this study reliably identified calcified urinary calculi in vivo.

Multi-slice computed tomography (MSCT) is a non-invasive modality to visualize coronary arteries with an overall good image quality. Improved spatial and temporal resolution of 64-slice and dual-source computed tomography (DSCT) scanners are supposed to have a positive impact on diagnostic accuracy and image quality. However, quantitative parameters to compare image quality of 16-slice, 64-slice MSCT and DSCT are missing. A total of 256 CT examinations were evaluated (Siemens, Sensation 16: n = 90; Siemens Sensation 64: n = 91; Siemens Definition: n = 75). Mean Hounsfield units (HU) were measured in the cavum of the left ventricle (LV), the ascending aorta (Ao), the left ventricular myocardium (My) and the proximal part of the left main (LM), the left anterior descending artery (LAD), the right coronary artery (RCA) and the circumflex artery (CX). Moreover, the ratio of intraluminal attenuation (HU) to myocardial attenuation was assessed for all coronary arteries. Clinical data [body mass index (BMI), gender, heart rate] were accessible for all patients. Mean attenuation (CA) of the coronary arteries was significantly higher for DSCT in comparison to 64- and 16-slice MSCT within the RCA [347 +/- 13 vs. 254 +/- 14 (64-MSCT) vs. 233 +/- 11 (16-MSCT) HU], LM (362 +/- 11/275 +/- 12/262 +/- 9), LAD (332 +/- 17/248 +/- 19/219 +/- 14) and LCX (310 +/- 12/210 +/- 13/221 +/- 10, all p < 0.05), whereas there was no significant difference between DSCT and 64-MSCT for the LV, the Ao and My. Heart rate had a significant impact on CA ratio in 16-slice and 64-slice CT only (p < 0.05). BMI had no impact on the CA ratio in DSCT only (p < 0.001). Improved spatial and temporal resolution of dual-source CT is associated with better opacification of the coronary arteries and a better contrast with the myocardium, which is independent of heart rate. In comparison to MSCT, opacification of the coronary arteries at DSCT is not affected by BMI. The main advantage of DSCT lies with the heart rate independency, which might have a positive impact on the diagnostic accuracy.

The aim of the study was to evaluate radiation exposure of a chest pain protocol with ECG-gated dual-source computed tomography (DSCT). An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a dual-source computed tomography system with a standard protocol for chest pain evaluation (120 kV, 320 mAs/rot) with different simulated heart rates (HRs). The dose of a standard chest CT examination (120 kV, 160 mAs) was also measured. Effective dose of the chest pain protocol was 19.3/21.9 mSv (male/female, HR 60), 17.9/20.4 mSv (male/female, HR 80) and 14.7/16.7 mSv (male/female, HR 100). Effective dose of a standard chest examination was 6.3 mSv (males) and 7.2 mSv (females). Radiation dose of the chest pain protocol increases significantly with a lower heart rate for both males (p = 0.040) and females (p = 0.044). The average radiation dose of a standard chest CT examination is about 36.5% that of a CT examination performed for chest pain. Using DSCT, the evaluated chest pain protocol revealed a higher radiation exposure compared with standard chest CT. Furthermore, HRs markedly influenced the dose exposure when using the ECG-gated chest pain protocol.

To assess HU-based color mapping for characterization of coronary plaque, using intravascular ultrasound virtual histology (IVUS-VH) as a standard of reference. Dual-source computed tomography and IVUS-VH were prospectively performed in 13 patients. In five lesions, HU thresholds of the color-coding software were calibrated to IVUS-VH. In a 15-lesion verification cohort, volumes of vessel, lumen and plaque or percentages of lipid, fibrous and calcified components were obtained through use of pre-set HU cut-offs as well as through purely visual adjustment of color maps. Calibrated HU ranges for fatty or fibrous plaque, lumen and calcification were -10-69, 70-158, 159-436 and 437+. Using these cut-offs, HU-based analysis achieved good agreement of plaque volume with IVUS (47.0 vs. 51.0 mm(3)). Visual segmentation led to significant overestimation of atheroma (61.6 vs. 51.0 mm(3); P = 0.04) Correlation coefficients for volumes of vessel, lumen and plaque were 0.92, 0.87 and 0.83 with HU-based analysis or 0.92, 0.85 and 0.71 with visual evaluation. With both methods, correlation of percentage plaque composition was poor or insignificant. HU-based plaque analysis showed good reproducibility with intra-class correlation coefficients being 0.90 for plaque volume and 0.81, 0.94 or 0.98 for percentages of fatty, fibrous or calcified components. With use of optimized HU thresholds, color mapping allows for accurate and reproducible quantification of coronary plaque.