Association of aortic diameters and mortality in the general population-an MRI-based study.

BACKGROUND: Increased diameters of the aorta are associated with increased mortality risk. In the present analyses, we assessed whether aortic diameters are associated with cardiovascular and all-cause mortality in community-dwelling individuals free of known cardiovascular disease (CVD). METHODS: MRI-derived vascular parameters of the thoracic and abdominal aorta from 2668 participants (median age = 53 years; 51.1% women) of the population-based SHIP-START-2 and SHIP-TREND-0 cohorts without CVD were analyzed. Age- and sex-adjusted, as well as multivariable-adjusted Cox-proportional hazard models, were used to estimate associations of diameters of six different aortic segments to mortality. RESULTS: Over a median follow-up time of 10.6 years (IQR: 8.7; 12.4), a total of 188 participants (126 men and 62 women) died, of which 38 deaths were due to CVD. In unadjusted models, mortality rates were higher in participants with aortic diameters above the median compared to below the median for all investigated aortic sections (all log-rank p < 0.001). In multivariable-adjusted models, the diameters of the ascending thoracic aorta (HR = 1.34 95% CI: 1.04; 1.72, p = 0.022) and of the infrarenal aorta (HR = 3.75 95% CI: 1.06; 13.3, p = 0.040), modeled continuously, were associated with greater cardiovascular mortality. The diameter of the subphrenic aorta was associated with higher cardiovascular mortality only in the age and sex-adjusted model (HR = 3.65 95% CI: 1.01; 13.3, p = 0.049). None of the investigated aortic segments were associated with all-cause mortality. CONCLUSION: Non-indexed diameters of the ascending thoracic and infrarenal aorta were associated with higher cardiovascular mortality but not with all-cause mortality in a population sample free of clinically overt CVD at baseline. CLINICAL RELEVANCE STATEMENT: Increased aortic diameter is associated with cardiovascular mortality and can help to identify high-risk patients. KEY POINTS: Increased aortic diameter is associated with mortality. Non-indexed diameters of the ascending and infrarenal aorta are associated with cardiovascular mortality but not all-cause mortality. Aortic diameter measurements support the estimate of cardiovascular mortality.

Virtual inverted classroom to replace in-person radiology lectures at the time of the COVID-19 pandemic - a prospective evaluation and historic comparison.

BACKGROUND: In the time of the coronavirus disease 2019 (COVID-19) pandemic, in-person lectures had to be shifted to online learning. This study aimed to evaluate students' and lecturers' perception and effectiveness of a virtual inverted classroom (VIC) concept on clinical radiology in comparison to a historic control. METHODS: In the winter semester 2020/21, 136 fourth year medical students who completed the clinical radiology VIC during the pandemic, were included in the single centre, prospective study. Results were compared with a historic control that had finished the physical inverted classroom (PIC) in the immediately preceding year. The VIC consisted of an initial phase of self-determined preparation with learning videos and a second interactive phase of clinical case studies alternating between the virtual lecture hall and virtual buzz groups. At the end of the lecture series, students rated the lecture on a scale of 1 (most positive assessment) to 6 (most negative assessment) through an online survey platform. Additionally, they reported their impressions in free-form text. Lecturers were invited to comment on the VIC in a group interview. Main outcomes were final grades and student perception of the VIC. RESULTS: Students' general impression of VIC was lower than that of PIC (median value of 3 [IQR 4, 2] and 1 [IQR 0, 0], p < 0.001), respectively, p < 0.001). The highest rating was achieved concerning use of the audience response system (median 1 [IQR 1, 0]), and the lowest concerning the buzz groups (median 4 [IQR 5, 3]). Students stated that they would have appreciated more details on reading images, greater focus on plenary case studies, and provision of exam related scripts. Lecturers would have liked better preparation by students, more activity of students, and stronger assistance for group support. Exam grades after VIC were better than after PIC (median 1 [IQR 2, 1] and 2 [IQR 2,1], respectively, p < 0.001). CONCLUSIONS: Students' overall perception of VIC was satisfactory, although worse than PIC. Final grades improved compared to PIC. Provided an adapted buzz group size and support, VIC may serve as complement in medical education once the pandemic is over.

Prevalence of Fatty Liver Disease and Hepatic Iron Overload in a Northeastern German Population by Using Quantitative MR Imaging.

Purpose To quantify liver fat and liver iron content by measurement of confounder-corrected proton density fat fraction (PDFF) and R2* and to identify clinical associations for fatty liver disease and liver iron overload and their prevalence in a large-scale population-based study. Materials and Methods From 2008 to 2013, 2561 white participants (1336 women; median age, 52 years; 25th and 75th quartiles, 42 and 62 years) were prospectively recruited to the Study of Health in Pomerania (SHIP). Complex chemical shift-encoded magnetic resonance (MR) examination of the liver was performed, from which PDFF and R2* were assessed. On the basis of previous histopathologic calibration, participants were stratified according to their liver fat and iron content as follows: none (PDFF, ≤5.1%; R2*, ≤41.0 sec-1), mild (PDFF, >5.1%; R2*, >41 sec-1), moderate (PDFF, >14.1%; R2*, >62.5 sec-1), high (PDFF: >28.0%; R2*: >70.1 sec-1). Prevalence of fatty liver diseases and iron overload was calculated (weighted by probability of participation). Clinical associations were identified by using boosting for generalized linear models. Results Median PDFF was 3.9% (range, 0.6%-41.5%). Prevalence of fatty liver diseases was 42.2% (1082 of 2561 participants); mild, 28.5% (730 participants); moderate, 12.0% (307 participants); high content, 1.8% (45 participants). Median R2* was 34.4 sec-1 (range, 14.0-311.8 sec-1). Iron overload was observed in 17.4% (447 of 2561 participants; mild, 14.7% [376 participants]; moderate, 0.8% [20 participants]; high content, 2.0% [50 participants]). Liver fat content correlated with waist-to-height ratio, alanine transaminase, uric acid, serum triglycerides, and blood pressure. Liver iron content correlated with mean serum corpuscular hemoglobin, male sex, and age. Conclusion In a white German population, the prevalence of fatty liver diseases and liver iron overload is 42.2% (1082 of 2561) and 17.4% (447 of 2561). Whereas liver fat is associated with predictors related to the metabolic syndrome, liver iron content is mainly associated with mean serum corpuscular hemoglobin. © RSNA, 2017 Online supplemental material is available for this article.

High levels of thyroid-stimulating hormone are associated with aortic wall thickness in the general population.

OBJECTIVES: Our aim was to investigate the association of thyroid function defined by serum concentrations of thyroid-stimulating hormone (TSH) with thoracic aortic wall thickness (AWT) as a marker of atherosclerotic processes. METHODS: We pooled data of 2,679 individuals from two independent population-based surveys of the Study of Health in Pomerania. Aortic diameter and AWT measurements were performed on a 1.5-T MRI scanner at the concentration of the right pulmonary artery displaying the ascending and the descending aorta. RESULTS: TSH, treated as continuous variable, was significantly associated with descending AWT (ß = 0.11; 95 % confidence interval (CI) 0.02-0.21), while the association with ascending AWT was not statistically significant (ß = 0.20; 95 % CI -0.01-0.21). High TSH (>3.29 mIU/L) was significantly associated with ascending (ß = 0.12; 95 % CI 0.02-0.23) but not with descending AWT (ß = 0.06; 95 % CI -0.04-0.16). There was no consistent association between TSH and aortic diameters. CONCLUSIONS: Our study demonstrated that AWT values increase with increasing serum TSH concentrations. Thus, a hypothyroid state may be indicative for aortic atherosclerosis. These results fit very well to the findings of previous studies pointing towards increased atherosclerotic risk in the hypothyroid state. KEY POINTS: • Serum TSH concentrations are positively associated with aortic wall thickness. • Serum TSH concentrations are not associated with the aortic diameters. • Serum 3,5-diiodothyronine concentrations may be positively associated with aortic wall thickness.

Thoracic and abdominal aortic diameters in a general population: MRI-based reference values and association with age and cardiovascular risk factors.

OBJECTIVES: To generate reference values for thoracic and abdominal aortic diameters determined by magnetic resonance imaging (MRI) and analyse their association with cardiovascular risk factors in the general population. METHODS: Data from participants (n = 1759) of the Study of Health in Pomerania were used for analysis in this study. MRI measurement of thoracic and abdominal aortic diameters was performed. Parameters for calculation of reference values according to age and sex analysis were provided. Multivariable linear regression models were used for determination of aortic diameter-related risk factors, including smoking, blood pressure (BP), high-density lipoprotein cholesterol (HDL-C). RESULTS: For the ascending aorta (ß = -0.049, p < 0.001), the aortic arch (ß = -0.061, p < 0.001) and the subphrenic aorta (ß = -0.018, p = 0.004), the body surface area (BSA)-adjusted diameters were lower in men. Multivariable-adjusted models revealed significant increases in BSA-adjusted diameters with age for all six aortic segments (p < 0.001). Consistent results for all segments were observed for the positive associations of diastolic BP (ß = 0.001; 0.004) and HDL (ß = 0.035; 0.087) with BSA-adjusted aortic diameters and for an inverse association of systolic BP (ß = -0.001). CONCLUSIONS: Some BSA-adjusted median aortic diameters are smaller in men than in women. All diameters increase with age, diastolic blood pressure and HDL-C and decrease as systolic BP increases. KEY POINTS: • Median aortic diameter increases with age and diastolic blood pressure. • Median aortic diameter is larger in men than in women. • Some BSA-adjusted median aortic diameters are smaller in men than in women.

Cardiovascular risk factors and thoracic aortic wall thickness in a general population.

PURPOSE: To evaluate the association of cardiovascular risk factors with wall thickness of the ascending and descending thoracic aorta in the general population. MATERIALS AND METHODS: The study included 1,176 individuals (523 women) 21-83 years old from the Study of Health in Pomerania without history of stroke or myocardial infarction. Aortic wall thickness (AWT) was determined by cine magnetic resonance imaging. The associations of AWT with the cardiovascular risk factors male sex, age, smoking, body mass index (BMI), systolic and diastolic blood pressure, hemoglobin A1c, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides were assessed by multivariable linear regression models, and interaction effects were tested. RESULTS: Male sex (ß = .086, P < .001), age (ß = .006, P < .001), and BMI (ß = .013, P < .001) were positively associated with the AWT of the ascending aorta. Male sex (ß = .105, P < .001), age (ß = .006, P < .001), current smoker (ß = .044, P = .010), BMI (ß = .013, P < .001), and HDL-C (ß = .057, P = .008) revealed a positive association with AWT of the descending aorta. LDL-C (ß = -.024, P = .009; ß = -.018, P = .010) was inversely associated with the AWT of the ascending and descending aorta, respectively. Triglyceride levels (ß = .024, P = .027; ß = .018, P = .024) showed a positive association with the AWT of the ascending and descending aorta, respectively, in men, but not in women. CONCLUSIONS: Established cardiovascular risk factors, including male sex, older age, smoking, high BMI, and high triglyceride levels, were associated with increasing thoracic AWT of the ascending and descending aorta. High HDL-C and low LDL-C levels were correlated with AWT.

Quantitative chemical shift-encoded MRI is an accurate method to quantify hepatic steatosis.

PURPOSE: To compare the accuracy of liver fat quantification using a three-echo chemical shift-encoded magnetic resonance imaging (MRI) technique without and with correction for confounders with spectroscopy (MRS) as the reference standard. MATERIALS AND METHODS: Fifty patients (23 women, mean age 56.6 ± 13.2 years) with fatty liver disease were enrolled. Patients underwent T2-corrected single-voxel MRS and a three-echo chemical shift-encoded gradient echo (GRE) sequence at 3.0T. MRI fat fraction (FF) was calculated without and with T2* and T1 correction and multispectral modeling of fat and compared with MRS-FF using linear regression. RESULTS: The spectroscopic range of liver fat was 0.11%-38.7%. Excellent correlation between MRS-FF and MRI-FF was observed when using T2* correction (R(2) = 0.96). With use of T2* correction alone, the slope was significantly different from 1 (1.16 ± 0.03, P < 0.001) and the intercept was different from 0 (1.14% ± 0.50%, P < 0.023). This slope was significantly different than 1.0 when no T1 correction was used (P = 0.001). When T2*, T1, and spectral complexity of fat were addressed, the results showed equivalence between fat quantification using MRI and MRS (slope: 1.02 ± 0.03, P = 0.528; intercept: 0.26% ± 0.46%, P = 0.572). CONCLUSION: Complex three-echo chemical shift-encoded MRI is equivalent to MRS for quantifying liver fat, but only with correction for T2* decay and T1 recovery and use of spectral modeling of fat. This is necessary because T2* decay, T1 recovery, and multispectral complexity of fat are processes which may otherwise bias the measurements.

MRI-based determination of reference values of thoracic aortic wall thickness in a general population.

OBJECTIVES: To provide age- and sex-specific reference values for MRI-derived wall thickness of the ascending and descending aorta in the general population. MATERIALS AND METHODS: Data of 753 subjects (311 females) aged 21-81 years were analysed. MRI was used to determine the aortic wall thickness (AWT). Equations for reference value calculation according to age were established for females and males. RESULTS: Median wall thickness of the ascending aorta was 1.46 mm (5th-95th range: 1.15-1.88 mm) for females and 1.56 mm (1.22-1.99 mm) for males. Median wall thickness of the descending aorta was 1.26 mm (0.97-1.58 mm) in females and 1.36 mm (1.04-1.75 mm) in males. While median and 5th and 95th percentiles for the ascending and descending aorta increased with age in both sexes, the association between age and median AWT was stronger in males than in females for both the ascending and descending aorta. CONCLUSIONS: Reference values for the ascending and descending AWT are provided. In a healthy sample from the general population, the wall of the ascending aorta is thicker than the wall of the descending aorta, and both walls are thicker in males than females. The increase in wall thickness with age is greater in males. KEY POINTS: Ascending aortic wall thickness is greater than descending aortic wall thickness. Ascending and descending aortic wall thickness is greater in males. Thoracic aortic wall thickness increases with age in both sexes. The age-related increase in aortic wall thickness is stronger in males.

Secretin-stimulated MRCP in volunteers: assessment of safety, duct visualization, and pancreatic exocrine function.

OBJECTIVE: The objective of our study was to investigate secretin-stimulated MRCP in terms of the safety of secretin, improvement of duct visualization, and assessment of pancreatic exocrine function. MATERIALS AND METHODS: Eight hundred sixteen volunteers (370 women and 446 men; mean age, 49.7 ± 13.1 [SD] years) underwent 3D MRCP before and after secretin stimulation (1 U/kg of body weight) at 1.5 T. For the first 2 hours after secretin injection, subjects were evaluated for adverse reactions. Improvement of duct visualization after secretin stimulation was subjectively evaluated by two readers and was quantified by duct diameter measurements. Pancreatic exocrine function was evaluated subjectively by two readers according to the duodenal filling and was quantified using calibrated volumetric measurements of total excreted volume and pancreatic flow output. RESULTS: Two subjects (0.2%) showed flushing (minor adverse reaction). Duct visualization after secretin injection was improved for reader 1 in 468 (57.4%) and for reader 2 in 478 (58.6%) subjects, was unchanged for reader 1 in 324 (39.7%) and for reader 2 in 315 (38.6%) subjects, and was worse for reader 1 in 24 (2.9%) and reader 2 in 23 (2.8%) subjects (interrater agreement, κ = 0.925). Main pancreatic duct diameters increased significantly after secretin stimulation: pancreatic head, 10.5% (mean); body, 12.5%; and tail, 7.7%. Pancreatic exocrine function evaluated according to assessment of duodenal filling was as follows: grade 0 (restricted function) in 0.7% of subjects by both readers, grade 1 (reduced function) in 4.8% of subjects by reader 1 and 4.5% of subjects by reader 2, grade 2 (low-grade reduced function) in 31.1% of subjects by reader 1 and 26.5% of subjects by reader 2, and grade 3 (physiologic function) in 63.4% of subjects by reader 1 and 68.3% of subjects by reader 2 (interrater agreement, κ = 0.838). The mean total excreted volume was 111.8 ± 49.8 (SD) mL, and the mean pancreatic flow output was 9.6 ± 4.2 mL/min. CONCLUSION: Secretin-stimulated MRCP moderately improves main pancreatic duct visualization and allows noninvasive quantification of pancreatic exocrine function with a negligible risk of side effects.

Age- and Sex-Specific Reference Values for Renal Volume and Association with Risk Factors for Chronic Kidney Disease in a General Population-An MRI-Based Study.

BACKGROUND: Renal volume (RV) is associated with renal function and with a variety of cardiovascular risk factors (CVRFs). We analysed RV using magnetic resonance imaging (MRI) in a large population-based study (Study of Health in Pomerania; SHIP-TREND) to find sex- and age-specific reference values for RV and to test the influence of several markers on RV. The main objective is to describe reference values for RV in people from the general population without kidney disease. METHODS: 1815 participants without kidney disease (930 women) aged 21-81 years were included in our study. Right and left RV with and without body surface area (BSA) indexation were compared among three age groups (22-39 years, 40-59 years, 60-81 years) by median and interquartile range and tested separately in women and men. RESULTS: The estimated glomerular filtration rate (eGFR), serum uric acid, and right and left RV were higher in men compared to women (all p < 0.001). Left kidneys were larger than right kidneys (both sexes). With age, RV showed a continuously decreasing trend in women and an upside-down U-shaped relation in men. In multivariable linear regression models, current smoking (ß = 14.96, 95% CI 12.12; 17.79), BSA (ß = 97.66, 95% CI 90.4; 104.93), diastolic blood pressure (ß = 0.17, 95% CI 0.01; 0.32), and eGFR (ß = 0.57, 95% CI 0.50; 0.65) were positively associated with both left and right RV, whereas uric acid (ß = -0.03, 95% CI -0.05; -0.01) showed an inverse association with RV. Interestingly, the same eGFR correlated with higher RV in men compared to women. CONCLUSION: Reference values for RV are different for age groups and sex. For any given age, female kidneys are smaller than male kidneys. RV associates positively with eGFR, but for any chosen eGFR, renal volume in females is lower compared to males. RV decreases with age, but in men showed a U-shaped correlation. This may reflect hyperfiltration and glomerular hypertrophy associated with the presence of CVRF in middle-aged males.

R2* estimation using "in-phase" echoes in the presence of fat: the effects of complex spectrum of fat.

PURPOSE: To investigate R2* mapping robustness in the presence of fat using in-phase echoes, without and with spectral modeling of fat (single-peak and multipeak models, respectively), using varying numbers of echoes. MATERIALS AND METHODS: Data from 88 volunteers (men/women: 52/36, ages: 55.4 ± 12.2) were randomly chosen according to magnetic resonance imaging (MRI) liver fat-fraction (%), and classified into six fat-fraction groups (1: 20 cases, 0%-<10%; 2: 20 cases, 10%-<20%; 3: 20 cases, 20%-<30%; 4: 20 cases, 30%-<40%; 5: 8 cases >40% liver fat; 6: subcutaneous fat from all cases). R2* maps obtained from five in-phase echoes (echo times: 4.8-23.8 msec) were retrospectively reconstructed using single-peak and multipeak fat modeling. R2* maps were also calculated using different numbers (2-5) of echoes. RESULTS: Multipeak fat corrected R2* mapping is feasible from in-phase echoes, with noise performance comparable to single-peak R2* when using ≥ 4 echoes. Single-peak R2* showed poor robustness to varying echo time combinations in the presence of fat, where using few echoes resulted in large errors. These errors can be reduced using more echoes, or fully corrected using multipeak fat modeling. The mean R2* increased significantly with increasing fat-fraction when using single-peak R2* for any TE combination (P < 0.001), but did not vary when using multipeak R2* for any TE combination (P ≥ 0.158). CONCLUSION: R2* mapping uncorrected for spectral complexity of fat contains protocol and fat-dependent errors (lack of robustness) in tissues with high fat content. Accounting for complex fat spectrum improves robustness and accuracy of signal fitting, with modest noise performance loss.

Diffusion-weighted magnetic resonance imaging for staging liver fibrosis is less reliable in the presence of fat and iron.

OBJECTIVES: To investigate the reliability of diffusion-weighted magnetic resonance imaging (DW-MRI) for staging liver fibrosis in the presence of fat and iron. METHODS: Ninety-five patients, including 48 men and 47 women, aged 57.0 ± 14.2 years, underwent liver biopsy. Ninety-six samples were histologically staged for liver fibrosis (0-Ishak score 0; 1-Ishak score 1-4; 2-Ishak score 5-6) and semiquantitatively graded for hepatic iron (0, no; 1, low; 2, moderate; 3, high iron) and for hepatic steatosis. Within 72 h after biopsy, navigator-triggered DW-MRI using b-values of 50/400/800 s/mm(2) was performed in a 1.5-T system, and apparent diffusion coefficients (ADC) were analysed. ADCs were correlated with fibrosis stage, steatosis grade, and iron grade using linear regression. RESULTS: ADC did not correlate with fibrosis stages in either the overall group (n = 96; R (2) = 0.38; P = 0.17) or in the subgroup without liver iron and steatosis (n = 40; R (2) = 0.01; P = 0.75). ADC decreased significantly with steatosis grade in cases without iron and fibrosis (n = 42; R (2) = 0.28; ß = -5.3; P < 0.001). Liver iron was modestly correlated with ADC in patients without fibrosis and steatosis (n = 33; R (2) = 0.29; P = 0.04), whereas high iron concentrations were associated with low ADC values (group 3: ß = -489; P = 0.005; reference:group 0) but intermediate levels were not (group 1/group 2: P = 0.93/P = 0.54; reference group: 0). CONCLUSIONS: ADC values are confounded by fat and iron. However, even in patients without fat or iron, DW-MRI does not adequately discriminate the stage of fibrosis. KEY POINTS: • Diffusion-weighted magnetic resonance imaging (DW-MRI) is increasingly used to evaluate liver disease. • DWI using b-values of 50/400/800 s/mm (2) does not adequately quantify fibrosis. • Assessment of the apparent diffusion coefficient (ADC) is confounded by fat and iron. • Fat may influence ADCs by altering water diffusion. • Iron may influence ADCs by signal decay and noise floor effects.

Effect of multipeak spectral modeling of fat for liver iron and fat quantification: correlation of biopsy with MR imaging results.

PURPOSE: To investigate the effect of the multipeak spectral modeling of fat on R2* values as measures of liver iron and on the quantification of liver fat fraction, with biopsy as the reference standard. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Patients with liver disease (n = 95; 50 men, 45 women; mean age, 57.2 years±14.1 [standard deviation]) underwent a nontargeted liver biopsy, and 97 biopsy samples were reviewed for steatosis and iron grades. MR imaging at 1.5 T was performed 24-72 hours after biopsy by using a three-echo three-dimensional gradient-echo sequence for water and fat separation. Data were reconstructed off-line, correcting for T1 and T2* effects. Fat fraction and R2* maps (1/T2*) were reconstructed and differences in R2* and steatosis grades with and without multipeak modeling of fat were tested by using the Kruskal-Wallis test. Spearman rank correlation coefficient was used to assess fat fractions and steatosis grades. Linear regression analysis was performed to compare the fat fraction for both models. RESULTS: Mean steatosis grade at biopsy ranged from 0% to 95%. Biopsy specimens in 26 of 97 patients (27%) showed liver iron (15 mild, six moderate, and five severe). In all 71 samples without iron, a strong increase in the apparent R2* was observed with increasing steatosis grade when single-peak modeling of fat was used (P=.001). When multipeak modeling was used, there were no differences in the apparent R2* as a function of steatosis grading (P=.645), and R2* values agreed closely with those reported in the literature. Good correlation between fat fraction and steatosis grade was observed (rS=0.85) both without and with spectral modeling. CONCLUSION: In the presence of fat, multipeak spectral modeling of fat improves the agreement between R2* and liver iron. Single-peak modeling of fat leads to underestimation of liver fat.

Impact of a Heutagogical, Multimedia-Based Teaching Concept to Promote Self-Determined, Cooperative Student Learning in Clinical Radiology.

PURPOSE: To date, didactic lecturing is a common method of university medical training. However, higher levels of competence to solve complex issues are hardly to be achieved with a largely passive learning style. We established and evaluated a heutagogical blended learning concept to investigate self-determined learning with a multimedia-based, interactive approach in the lecture room to teach clinical radiology. MATERIALS AND METHODS: In the 2019/2020 winter semester, we included 266 medical students in their fourth academic year in our prospective, observational study. Students participated in a series of 11 radiological lectures given by 10 lecturers. They were requested to prepare for lectures by watching learning videos. During the lecture, students had to answer key-feature questions (KFQ) in small groups and to jointly submit their answers by means of an audience response system (ARS). After each lecture and the exam, we conducted surveys and compared results with a historical control group. A focus group interview with lecturers was performed after conclusion of the lecture series. RESULTS: The students' overall impression of the "flipped classroom" concept and their examination grades were superior to historical controls (overall impression: 1.5 [95 % CI 1.4-1.6] vs. 2.7 [95 % CI 2.5-2.9] rated on a scale from 1 to 6, p < 0.001; examination grades: 1.8 [95 % CI 1.7-1.9] vs. 2.0 [95 % CI 1.9-2.0] rated on a scale from 1 to 5, p < 0.001). Most students agreed that learning videos (76.6 %), ARS (88.5 %), KFQ (76.5 %), and solution-oriented small group discussions (83.7 %) were useful. Lecturers stated an improved convergence of demands on learning and clinical competence. However, they also emphasized an increased initial effort for implementation. CONCLUSION: Students rated the overall benefit from the heutagogical "flipped classroom" concept as high. Examination grades improved. According to lecturers, the "flipped classroom" concept better matched later professional demands than traditional lectures. KEY POINTS: · The benefit of the "flipped classroom" concept for radiological lectures was rated high by students.. · Most students were satisfied with the multimedia and interactive elements of lectures.. · Lecturers considered heutagogical learning demands as appropriate for later clinical requirements.. CITATION FORMAT: · Teichgräber U, Ingwersen M, Mentzel H et al. Impact of a Heutagogical, Multimedia-Based Teaching Concept to Promote Self-Determined, Cooperative Student Learning in Clinical Radiology. Fortschr Röntgenstr 2021; 193: 701 - 711.

Association between hepatic fat and subclinical vascular disease burden in the general population.

OBJECTIVE: It is still controversial if increased hepatic fat independently contributes to cardiovascular risk. We aimed to assess the association between hepatic fat quantified by MRI and various subclinical vascular disease parameters. DESIGN: We included two cross-sectional investigations embedded in two independent population-based studies (Study of Health in Pomerania (SHIP): n=1341; Cooperative Health Research in the Region of Augsburg (KORA): n=386). The participants underwent a whole-body MRI examination. Hepatic fat content was quantified by proton-density fat fraction (PDFF). Aortic diameters in both studies and carotid plaque-related parameters in KORA were measured with MRI. In SHIP, carotid intima-media thickness (cIMT) and plaque were assessed by ultrasound. We used (ordered) logistic or linear regression to assess associations between hepatic fat and subclinical vascular disease. RESULTS: The prevalence of fatty liver disease (FLD) (PDFF >5.6%) was 35% in SHIP and 43% in KORA. In SHIP, hepatic fat was positively associated with ascending (ß, 95% CI 0.06 (0.04 to 0.08)), descending (0.05 (0.04 to 0.07)) and infrarenal (0.02 (0.01 to 0.03)) aortic diameters, as well as with higher odds of plaque presence (OR, 95% CI 1.22 (1.05 to 1.42)) and greater cIMT (ß, 95% CI 0.01 (0.004 to 0.02)) in the age-adjusted and sex-adjusted model. However, further adjustment for additional cardiometabolic risk factors, particularly body mass index, attenuated these associations. In KORA, no significant associations were found. CONCLUSIONS: The relation between hepatic fat and subclinical vascular disease was not independent of overall adiposity. Given the close relation of FLD with cardiometabolic risk factors, people with FLD should still be prioritised for cardiovascular disease screening.

Prevalence and risk factors of perirenal hyperintensities on T2-weighted MR imaging.

OBJECTIVES: To assess the prevalence and severity of perirenal hyperintensities (PRHs) on T2-weighted magnetic resonance imaging (MRI) and their risk factors in the general population. METHODS: 1752 participants (910 women, 842 men, median age: 52 years) of the Study of Health in Pomerania were included. A visual classification system was established to assess the severity of PRHs (stage 0: no PRHs visible to stage 3: extensive PRHs visible). The MRI-derived thickness of the perirenal and posterior pararenal space and additional risk factors were determined and associated with PRH stages. RESULTS: The overall prevalence of PRHs was 40.7% and was higher in men than in women. PRHs were more common around the left compared to the right kidney (p < 0.001). On both sides, the presence of PRHs was associated with age (p < 0.001). Multivariable-adjusted regression models revealed male sex (OR = 13.2, 95%CI 9.7; 17.9, p < 0.001), older age (OR = 1.1, 95%CI 1.1; 1.1, p < 0.001), higher body mass index (BMI; OR = 1.1, 95%CI 1.0; 1.1, p < 0.001), current smoking status (OR = 1.9, 95%CI 1.4; 2.6, p < 0.001), and greater thickness of the posterior pararenal space (OR = 1.2, 95%CI 1.2; 1.2, p < 0.001) as independent significant risk factors of left-sided PRHs. The same risk factors were confirmed for right PRHs. Glomerular filtration rate was not associated with PRHs on either sides (OR = 1.00, 95%CI 1.0;1.0, p > 0.05). CONCLUSIONS: PRHs are common in the general population, with a higher prevalence in men, elderly individuals, and around the left kidney. Furthermore, BMI, posterior pararenal space thickness, and current smoking, but not renal function itself, are associated with the presence of PRHs.

Local Intra-arterial Vasodilator Infusion in Non-Occlusive Mesenteric Ischemia Significantly Increases Survival Rate.

PURPOSE: To investigate the outcome of local intra-arterial papaverine infusion therapy in patients with non-occlusive mesenteric ischemia (NOMI), and factors influencing survival, in comparison with a conservative approach. METHODS: From 2013 to 2019, patients with NOMI confirmed by imaging were included in a retrospective two-center study. According to different in-house standard procedures, patients were treated in each center either conservatively or interventionally by a standardized local infusion of intra-arterial papaverine into the splanchnic arteries. Thirty-day mortality and factors influencing the outcome, such as different demographics and laboratories, were compared between groups using Kaplan-Meier survival analysis and Cox regression, respectively. RESULTS: A total of 66 patients with NOMI were included, with n = 35 treated interventionally (21 males, mean age 67.7 ± 12.3 years) and n = 31 treated conservatively (18 females, mean age 71.6 ± 9.6 years). There was a significant difference in 30-day mortality between the interventional (65.7%; 12/35 survived) and the conservative group (96.8%; 1/31 survived) (hazard ratio 2.44; P = 0.005). Thresholds associated with a worse outcome of interventional therapy are > 7.68 mmol/l for lactate, < 7.31 for pH and < - 4.55 for base excess. CONCLUSION: Local intra-arterial papaverine infusion therapy in patients with NOMI significantly increases survival rate in comparison with conservative treatment. High lactate levels, low pH and high base excess, and high demand for catecholamines are associated with a poor outcome. LEVEL OF EVIDENCE: Level III.

Software-based noise reduction in cranial magnetic resonance imaging: Influence on image quality.

OBJECTIVES: To investigate acoustic noise reduction, image quality and white matter lesion detection rates of cranial magnetic resonance imaging (MRI) scans acquired with and without sequence-based acoustic noise reduction software. MATERIAL AND METHODS: Thirty-one patients, including 18 men and 13 women, with a mean age of 58.3±14.5 years underwent cranial MRI. A fluid-attenuated inversion recovery (FLAIR) sequence was acquired with and without acoustic noise reduction using the Quiet Suite (QS) software (Siemens Healthcare). During data acquisition, peak sound pressure levels were measured with a sound level meter (Testo, Typ 815). In addition, two observers assessed subjective image quality for both sequences using a five-point scale (1 very good-5 inadequate). Signal-to-noise ratio (SNR) was measured for both sequences in the following regions: white matter, gray matter, and cerebrospinal fluid. Furthermore, lesion detection rates in white matter pathologies were evaluated by two observers for both sequences. Acoustic noise, image quality including SNR and white matter lesion detection rates were compared using the Mann-Whitney-U-test. RESULTS: Peak sound pressure levels were slightly but significantly reduced using QS, P≤0.017. Effective sound pressure, measured in Pascal, was decreased by 19.7%. There was no significant difference in subjective image quality between FLAIR sequences acquired without/with QS: observer 1: 2.03/2.07, P = 0.730; observer 2: 1.98/2.10, P = 0.362. In addition, SNR was significantly increased in white matter, P≤0.001, and gray matter, P = 0.006, using QS. The lesion detection rates did not decline utilizing QS: observer 1: P = 0.944 observer 2: P = 0.952. CONCLUSIONS: Sequence-based noise reduction software such as QS can significantly reduce peak sound pressure levels, without a loss of subjective image quality and increase SNR at constant lesion detection rates.

Prevalence of renal cysts and association with risk factors in a general population: an MRI-based study.

PURPOSE: To assess the prevalence and size of renal cysts and to analyze associated risk factors in a general population using magnetic resonance imaging (MRI). METHODS: Data of 2063 participants (1052 women) of the Study of Health in Pomerania who underwent whole-body MRI were included. Renal cyst prevalence was calculated separately for men and women and for 10-year age groups. The association between risk factors and occurrence of renal cysts was estimated. RESULTS: The prevalence of renal cysts was 27% and higher in men (34%) than in women (21%; p < 0.001). Renal cyst prevalence increased from 14% in the youngest age group (20-29 years) to 55% in the oldest age group (≥ 70 years) for men and from 7% to 43% for women (both p < 0.001). In the subset of participants with renal cysts, the total mean number was higher in men (1.9) compared to women (1.6, p = 0.012) and was significantly associated with age. Mean renal cyst size was higher in men (1.50 cm) compared to women (1.18 cm, p < 0.001). Male sex (OR 1.83, 95% CI 1.47; 2.26), older age (OR 1.05, 95% CI 1.04; 1.06, per 1-year increment), and hypertension (OR 1.27, 95% CI 1.00; 1.61) were associated with higher renal cyst prevalence. In additional analyses, current smoking and ex-smoking showed a significantly higher risk for renal cysts (OR 1.47, 95% CI 1.05; 2.05 and OR 1.38, 95% CI 1.04; 1.82, respectively). CONCLUSIONS: The prevalence, number, and mean size of renal cysts are higher in men compared to women and are associated with age. In addition, renal cyst prevalence is higher in hypertensive and smoking subjects.

Reference values of vessel diameters, stenosis prevalence, and arterial variations of the lower limb arteries in a male population sample using contrast-enhanced MR angiography.

INTRODUCTION: Morphological characterization of leg arteries is of significant importance to detect vascular remodeling triggered by atherosclerotic changes. We determined reference values of vessel diameters and assessed prevalence of stenosis and arterial variations of the lower limb arteries in a healthy male population sample. METHODS: Gadolinium-enhanced magnetic resonance angiography at 1.5 Tesla was performed in 756 male participants (median age = 52 years, range = 21-82 years) of the population-based Study of Health in Pomerania. Vessel diameters were measured in 9 predefined segments of the pelvic and leg arteries and 95th percentiles were used for upper reference values of means of left and right side arteries. RESULTS: Reference values of vascular diameters decreased from proximal to distal arteries: common iliac = 1.18cm; internal iliac = 0.75cm; external iliac = 1.03cm; proximal femoral = 1.02cm; distal femoral = 0.77cm; popliteal = 0.69cm; anterior tibial = 0.42cm; posterior tibial = 0.38cm; fibular = 0.40cm. Body-surface area indexed reference values increased with age in all segments. A number of 53 subjects (7.0%) had at least one stenosis, mainly in the lower leg arteries anterior tibial (n = 28, 3.7%), posterior tibial (n = 18, 2.4%) and fibular (n = 20, 2.6%). The risk of stenosis increased considerably with age (odds ratio = 1.08; p<0.001). The most common arterial variant was type I-A in both legs (n = 620, 82%). CONCLUSION: We present reference values for different pelvic and leg artery segment diameters in men that decrease from proximal to distal and increase with age. Stenoses were most prevalent in lower leg arteries and type I-A was the most common variant in the lower leg.