Discrimination of benign, atypical, and malignant peripheral nerve sheath tumors in neurofibromatosis type 1 using diffusion-weighted MRI.

Background: Neurofibromatosis type 1 (NF1) is associated with the development of benign (BPNST) and malignant (MPNST) peripheral nerve sheath tumors. Recently described atypical neurofibromas (ANF) are considered pre-malignant precursor lesions to MPNSTs. Previous studies indicate that diffusion-weighted magnetic resonance imaging (DW-MRI) can reliably discriminate MPNSTs from BPNSTs. We therefore investigated the diagnostic accuracy of DW-MRI for the discrimination of benign, atypical, and malignant peripheral nerve sheath tumors. Methods: In this prospective explorative single-center phase II diagnostic study, 44 NF1 patients (23 male; 30.1 ±â€…11.8 years) underwent DW-MRI (b-values 0-800 s/mm²) at 3T. Two radiologists independently assessed mean and minimum apparent diffusion coefficients (ADCmean/min) in areas of largest tumor diameters and ADCdark in areas of lowest signal intensity by manual contouring of the tumor margins of 60 BPNSTs, 13 ANFs, and 21 MPNSTs. Follow-up of ≥ 24 months (BPNSTs) or histopathological evaluation (ANFs + MPNSTs) served as diagnostic reference standard. Diagnostic ADC-based cut-off values for discrimination of the three tumor groups were chosen to yield the highest possible specificity while maintaining a clinically acceptable sensitivity. Results: ADC values of pre-malignant ANFs clustered between BPNSTs and MPNSTs. Best BPNST vs. ANF + MPNST discrimination was obtained using ADCdark at a cut-off value of 1.6 × 10-3 mm2/s (85.3% sensitivity, 93.3% specificity), corresponding to an AUC of 94.3% (95% confidence interval: 85.2-98.0). Regarding BPNST + ANF vs. MPNST, best discrimination was obtained using an ADCdark cut-off value of 1.4 × 10-3 mm2/s (83.3% sensitivity, 94.5% specificity). Conclusions: DW-MRI using ADCdark allows specific and noninvasive discrimination of benign, atypical, and malignant nerve sheath tumors in NF1.

Current Imaging Strategies in Patients with Abdominal Aortic Aneurysms.

BACKGROUND: An abdominal aortic aneurysm (AAA) is defined as a localized dilatation of the abdominal aorta of ≥ 3 cm. With a prevalence of 4-8 %, AAA is one of the most common vascular diseases in Western society. Radiological imaging is an elementary component in the diagnosis, monitoring, and treatment planning of AAA patients. METHOD: This is a narrative review article on preoperative imaging strategies of AAA, incorporating expert opinions based on the current literature and standard-of-care practices from our own center. Examples are provided to illustrate clinical cases from our institution. RESULTS AND CONCLUSION: Radiological imaging plays a pivotal role in the initial diagnosis and monitoring of patients with AAA. Ultrasound is the mainstay imaging modality for AAA screening and surveillance. Contrast-enhanced CT angiography is currently considered the gold standard for preoperative imaging and image-based treatment planning in AAA repair. New non-contrast MR angiography techniques are robustly applicable and allow precise determination of aortic diameters, which is of critical importance, particularly with regard to current diameter-based surgical treatment guidelines. 3D imaging with multiplanar reformation and automatic centerline positioning enables more accurate assessment of the maximum aortic diameter. Modern imaging techniques such as 4D flow MRI have the potential to further improve individualized risk stratification in patients with AAA. KEY POINTS: · Ultrasound is the mainstay imaging modality for AAA screening and monitoring. · Contrast-enhanced CT angiography is the gold standard for preoperative imaging in AAA repair. · Non-contrast MR angiography allows for accurate monitoring of aortic diameters in AAA patients. · Measurement of aortic diameters is more accurate with 3D-CT/MRI compared to ultrasound. · Research seeks new quantitative imaging biomarkers for AAA risk stratification, e. g., using 4D flow MRI.

Value of patient-reported outcome measures for evaluating the benefit of speech processor upgrading in patients with cochlear implants.

BACKGROUND: Patients with a cochlear implant (CI) should be evaluated for a new speech processor every 6 years. The aim of this analysis was to assess the subjective and audiological benefit of upgrades. METHODS: Speech understanding and subjective benefit were analyzed in 99 patients with the old and the new speech processor after 4 weeks of wearing. Speech understanding was assessed using the Freiburg monosyllabic test in quiet (FBE) at 65 dB and 80 dB, and the Oldenburg Sentence Test (OLSA) at 65 dB noise with adaptive speech sound level. The Abbreviated Profile of Hearing Aid Benefit (APHAB) was used to assess subjective hearing impairment, and the Audio Processor Satisfaction Questionnaire (APSQ) was used to assess subjective satisfaction. RESULTS: The speech processor upgrade resulted in a significant improvement of speech understanding in quiet at 65 dB (mean difference 8.9 ± 25.9 percentage points, p < 0.001) and 80 dB (mean difference 8.1 ± 29.7 percentage points, p < 0.001) and in noise (mean difference 3.2 ± 10.7 dB signal-to-noise ratio [S/N], p = 0.006). Using the APHAB, a significant improvement (mean difference 0.07 ± 0.16, p < 0.001) in hearing impairment was demonstrated in all listening situations. The APSQ showed significantly higher patient satisfaction with the new speech processor (mean difference 0.42 ± 1.26, p = 0.006). A comparative assessment of the benefit based on subjective and speech audiometric results identified a proportion of patients (35-42%) who subjectively benefited from the upgrade but had no measurable benefit based on speech audiometry. CONCLUSION: There was a significant improvement in audiologically measurable and subjectively reflected speech understanding and patient satisfaction after the upgrade. In patients with only a small improvement in audiologically measurable speech understanding, the subjective benefit should also be assessed with validated measurement instruments in order to justify an upgrade to the payers in the health sector.

[Value of patient-reported outcome measures for evaluating the benefit of speech processor upgrading in patients with cochlear implants. German version]. / Wertigkeit von Patient-Reported Outcome Measures zur Bewertung des Versorgungsvorteils der Sprachprozessorumversorgung bei Patient/-innen mit Cochleaimplantaten.

BACKGROUND: Patients with a cochlear implant (CI) should be evaluated for a new speech processor every 6 years. The aim of this analysis was to assess the subjective and audiological benefit of upgrades. METHODS: Speech understanding and subjective benefit were analyzed in 99 patients with the old and the new speech processor after 4 weeks of wearing. Speech understanding was assessed using the Freiburg monosyllabic test in quiet (FBE) at 65 dB and 80 dB, and the Oldenburg Sentence Test (OLSA) at 65 dB noise with adaptive speech sound level. The Abbreviated Profile of Hearing Aid Benefit (APHAB) was used to assess subjective hearing impairment, and the Audio Processor Satisfaction Questionnaire (APSQ) was used to assess subjective satisfaction. RESULTS: The speech processor upgrade resulted in a significant improvement of speech understanding in quiet at 65 dB (mean difference 8.9 ± 25.9 percentage points, p < 0.001) and 80 dB (mean difference 8.1 ± 29.7 percentage points, p < 0.001) and in noise (mean difference 3.2 ± 10.7 dB signal-to-noise ratio [S/N], p = 0.006). Using the APHAB, a significant improvement (mean difference 0.07 ± 0.16, p < 0.001) in hearing impairment was demonstrated in all listening situations. The APSQ showed significantly higher patient satisfaction with the new speech processor (mean difference 0.42 ± 1.26, p = 0.006). A comparative assessment of the benefit based on subjective and speech audiometric results identified a proportion of patients (35-42%) who subjectively benefited from the upgrade but had no measurable benefit based on speech audiometry. CONCLUSION: There was a significant improvement in audiologically measurable and subjectively reflected speech understanding and patient satisfaction after the upgrade. In patients with only a small improvement in audiologically measurable speech understanding, the subjective benefit should also be assessed with validated measurement instruments in order to justify an upgrade to the payers in the health sector.

Cardiac T1 mapping enables risk prediction of LV dysfunction after surgery for aortic regurgitation.

Background: To assess whether cardiac T1 mapping for detecting myocardial fibrosis enables preoperative identification of patients at risk for early left ventricular dysfunction after surgery of aortic regurgitation. Methods: 1.5 Tesla cardiac magnetic resonance imaging was performed in 40 consecutive aortic regurgitation patients before aortic valve surgery. Native and post-contrast T1 mapping was performed using a modified Look-Locker inversion-recovery sequence. Serial echocardiography was performed at baseline and 8 ± 5 days after aortic valve surgery to quantify LV dysfunction. Receiver operating characteristic analysis was performed to determine the diagnostic accuracy of native T1 mapping and extracellular volume for predicting postoperative LV ejection fraction decrease >-10% after aortic valve surgery. Results: Native T1 was significantly increased in patients with a postoperatively decreased LVEF (n = 15) vs. patients with a preserved postoperative LV ejection fraction (n = 25) (i.e., 1,071 ± 67 ms vs. 1,019 ± 33 ms, p = .001). Extracellular volume was not significantly different between patients with preserved vs. decreased postoperative LV ejection fraction. With a cutoff-of value of 1,053 ms, native T1 yielded an area under the curve (AUC) of .820 (95% CI: .683-.958) for differentiating between patients with preserved vs. reduced LV ejection fraction with 70% sensitivity and 84% specificity. Conclusion: Increased preoperative native T1 is associated with a significantly higher risk of systolic LV dysfunction early after aortic valve surgery in aortic regurgitation patients. Native T1 could be a promising tool to optimize the timing of aortic valve surgery in patients with aortic regurgitation to prevent early postoperative LV dysfunction.

Longitudinal follow-up by MR angiography reveals progressive dilatation of the distal aorta after aortic root replacement in Marfan syndrome.

OBJECTIVES: To define and compare growth rates of the distal aorta in Marfan patients with and without aortic root replacement using serial MR angiography (MRA). METHODS: We retrospectively included 136 Marfan patients with a total of 645 MRAs who underwent a median of five MRAs (range: 2-13) at 1.5 T and 3 T in annual intervals. Of these, 41 patients (34.8 ± 12 years) had undergone aortic root replacement. The remaining 95 patients (29.0 ± 17 years) still had a native aorta and served as the control group. Thoracic aortic diameters were independently measured at eleven predefined levels. Estimated growth rates were calculated using a mixed effects model adjusted for sex, age, BMI, and medication. RESULTS: Marfan patients with aortic root replacement revealed the highest mean estimated growth rate in the proximal descending aorta (0.77 mm/year, CI: 0.31-1.21). Mean growth rates at all levels of the distal thoracic aorta were significantly higher in patients with aortic root replacement (0.28-0.77 mm/year) when compared to patients without aortic root replacement (0.03-0.07 mm/year) (all p < 0.001). Antihypertensive medication, gender, and BMI had no significant impact on the distal aortic growth rates. CONCLUSION: Distal thoracic aortic diameters increase at a significantly higher rate in Marfan patients with aortic root replacement compared to Marfan patients without aortic root replacement. Further studies are warranted to investigate if the increased growth rate of the distal thoracic aorta after aortic root replacement is caused by altered hemodynamics due to the rigid aortic root graft or due to the general genetic disposition of post-operative Marfan patients. CLINICAL RELEVANCE STATEMENT: High growth rates of the distal aorta after aortic root replacement underline the need for careful life-long aortic imaging of Marfan patients after aortic root replacement. KEY POINTS: • Aortic growth rates in Marfan patients with aortic root replacement are highest in the mid-aortic arch, the proximal- and mid-descending aorta. • Growth rates of the distal thoracic aorta are significantly higher in Marfan patients with aortic root replacement compared to Marfan patients without aortic root replacement. • Antihypertensive medication, gender, and BMI have no significant impact on distal aortic growth rates in Marfan patients.

4D flow MRI-guided treatment of portal-hypertensive complications in a patient with multiple extrahepatic arterioportal shunts.

Portal hypertension is the underlying reason for complications like ascites or gastrointestinal varices in end-stage liver disease. On rare occasions, portal hypertension may be caused by extrahepatic arterioportal shunts. This report illustrates an outstanding case of extrahepatic arterioportal shunting as an uncommon cause of TIPS-refractory portal hypertension. Four-dimensional flow magnetic resonance imaging (4D flow MRI) is a novel non-invasive technique that enables the visualization of complex vascular disorders but has not been put into daily clinical practice in hepatology. In this case, 4D flow MRI enabled the visualization of three abdominal arterioportal shunts as the reason for TIPS-refractory portal hypertension. The quantification of individual shunt flow rates by 4D flow MRI guided our treatment strategy consisting of embolization during interventional angiography and surgical resection of all three arterioportal shunts. In conclusion, this case highlights the usefulness of 4D flow MRI for evaluating shunt flow in cases of complex vascular disorders and portal-hypertensive complications, thus helping to guide therapeutic decisions and monitoring the therapeutic success.

Validation of 4D flow cardiovascular magnetic resonance in TIPS stent grafts using a 3D-printed flow phantom.

BACKGROUND: Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) is feasible for portal blood flow evaluation after placement of transjugular intrahepatic portosystemic shunts (TIPS) in patients with liver cirrhosis. However, clinical acceptance of 4D flow CMR in TIPS patients is limited due to the lack of validation studies. The purpose of this study was to validate 4D flow CMR-derived measurements in TIPS stent grafts using a three-dimensional (3D)-printed flow phantom. METHODS: A translucent flow phantom of the portal vasculature was 3D-printed. The phantom consisted of the superior mesenteric vein and the splenic vein draining into the portal vein, the TIPS-tract, and the hepatic vein. A TIPS stent graft (Gore® Viatorr®) was positioned within the TIPS-tract. Superior mesenteric vein and splenic vein served as inlets for blood-mimicking fluid. 4D flow CMR acquisitions were performed at 3T at preset flow rates of 0.8 to 2.8 l/min using velocity encoding of both 1.0 and 2.0 m/s. Flow rates and velocities were measured at predefined levels in the portal vasculature and within the stent graft. Accuracy of 4D flow CMR was assessed through linear regression with reference measurements obtained by flow sensors and two-dimensional (2D) phase contrast (PC) CMR. Intra- and interobserver agreement were assessed through Bland-Altman analyses. RESULTS: At a velocity encoding of 2.0 m/s, 4D flow CMR-derived flow rates and velocities showed an excellent correlation with preset flow rates and 2D PC CMR-derived flow velocities at all vascular levels and within the stent graft (all r ≥ 0.958, p ≤ 0.003). At a velocity encoding of 1.0 m/s, aliasing artifacts were present within the stent graft at flow rates ≥ 2.0 l/min. 4D flow CMR-derived measurements revealed high intra- and interobserver agreement. CONCLUSIONS: The in vitro accuracy and precision of 4D flow CMR is unaffected by the presence of TIPS stent grafts, suggesting that 4D flow CMR may be used to monitor TIPS patency in patients with liver cirrhosis.

Intuitive teaching of medical device operation to clinical assistance robots.

PURPOSE: The adjustment of medical devices in the operating room is currently done by the circulating nurses. As digital interfaces for the devices are not foreseeable in the near future and to incorporate legacy devices, the robotic operation of medical devices is an open topic. METHODS: We propose a teleoperated learning from demonstration process to acquire the high-level device functionality with given motion primitives. The proposed system is validated using an insufflator as an exemplary medical device. RESULTS: At the beginning of the proposed learning period, the teacher annotates the user interface to obtain the outline of the medical device. During the demonstrated interactions, the system observes the state change of the device to generalize logical rules describing the internal functionality. The combination of the internal logics with the interface annotations enable the robotic system to adjust the medical device autonomously. To interact with the device, a robotic manipulator with a finger-like end-effector is used while relying on haptic feedback from torque sensors. CONCLUSION: The proposed approach is a first step towards teaching a robotic system to operate medical devices. We aim at validating the system in an extensive user study with clinical personnel. The logical rule generalization and the logical rule inference based on computer vision methods will be focused in the future.

Assessment of aortic diameter in Marfan patients: intraindividual comparison of 3D-Dixon and 2D-SSFP magnetic resonance imaging.

OBJECTIVES: To compare the accuracy and precision of 3D-Dixon and 2D-SSFP MR-imaging for assessment of aortic diameter in Marfan patients. METHODS: This prospective single-center study investigated respiratory-gated 3D-Dixon and breath-hold 2D-SSFP non-contrast MR-imaging at 3 T in 47 Marfan patients (36.0 ± 13.2 years, 28♀,19♂). Two radiologists performed individual diameter measurements at five levels of the thoracic aorta and evaluated image quality on a four-grade scale (1 = poor, 4 = excellent) and artifacts (1 = severe, 4 = none). Aortic root diameters acquired by echocardiography served as a reference standard. Intraclass correlation coefficient, Bland-Altman analyses, F-test, t-test, and regression analyses were used to assess agreement between observers and methods. RESULTS: Greatest aortic diameters were observed at the level of the sinuses of Valsalva (SOV) for 3D-Dixon (38.2 ± 6.8 mm) and 2D-SSFP (38.3 ± 7.1 mm) (p = 0.53). Intra- and interobserver correlation of diameter measurements was excellent at all aortic levels for both 3D-Dixon (r = 0.94-0.99 and r = 0.94-0.98) and 2D-SSFP (r = 0.96-1.00 and r = 0.95-0.99). 3D-Dixon-derived and 2D-SSFP-derived diameter measurements at the level of the SOV revealed a strong correlation with echocardiographic measurements (r = 0.92, p < 0.001 and r = 0.93, p < 0.001, respectively). The estimated mean image quality at the level of SOV was higher for 2D-SSFP compared to that for 3D-Dixon (3.3 (95%-CI: 3.1-3.5) vs. 2.9 (95%-CI: 2.7-3.1)) (p < 0.001). Imaging artifacts were less at all aortic levels for 3D-Dixon compared to 2D-SSFP (3.4-3.8 vs. 2.8-3.1) (all p < 0.002). CONCLUSION: Respiratory-gated 3D-Dixon and breath-hold 2D-SSFP MR-imaging provide accurate and precise aortic diameter measurements. We recommend 3D-Dixon imaging for monitoring of aortic diameter in Marfan patients due to fewer imaging artifacts and the possibility of orthogonal multiplanar reformations of the aortic root. KEY POINTS: • Respiratory-gated 3D-Dixon and breath-hold 2D-SSFP imaging provide accurate and precise aortic diameter measurements in patients suffering from Marfan syndrome. • Imaging artifacts are stronger in 2D-SFFP imaging than in 3D-Dixon imaging. • We recommend 3D-Dixon imaging for monitoring of aortic diameter in Marfan patients due to fewer imaging artifacts and the possibility of orthogonal multiplanar reformations.

Liver cirrhosis in children - the role of imaging in the diagnostic pathway.

Liver cirrhosis in children is a rare disease with multifactorial causes that are distinct from those in adults. Underlying reasons include cholestatic, viral, autoimmune, hereditary, metabolic and cardiac disorders. Early detection of fibrosis is important as clinical stabilization or even reversal of fibrosis can be achieved in some disorders with adequate treatment. This article focuses on the longitudinal evaluation of children with chronic liver disease with noninvasive imaging tools, which play an important role in detecting cirrhosis, defining underlying causes, grading fibrosis and monitoring patients during follow-up. Ultrasound is the primary imaging modality and it is used in a multiparametric fashion. Magnetic resonance imaging and computed tomography are usually applied second line for refined tissue characterization, clarification of nodular lesions and full delineation of abdominal vessels, including portosystemic communications.

Pre-interventional assessment of right renal to right adrenal vein distance: Impact on procedure time and radiation dose in adrenal vein sampling.

PURPOSE: Adrenal vein sampling (AVS) is the reference standard for evaluation of lateralized hormone production in primary aldosteronism. We aimed to investigate the impact of pre-interventional right renal vein (RRV) to right adrenal vein (RAV) distance measurement on fluoroscopy time, contrast agent exposure and radiation dose during AVS. MATERIALS AND METHODS: Forty-five patients with primary aldosteronism undergoing AVS were enrolled in our retrospective study and divided into three groups. In the group "ruler" (n = 14), RRV-RAV-distances were determined pre-interventionally by cross-sectional imaging (CT/MRI) and AVS was performed by one interventional radiologist with limited experience in AVS. CT/MRI-derived and fluoroscopy-derived RRV-RAV-distances were correlated for aimed cannulation of the RAV. Patients in group "no ruler" (n = 24, three interventional radiologists with limited experience in AVS) and in group "expert", (n = 7, one expert interventional radiologist) underwent AVS without pre-interventional estimation of RRV-RAV-distances. Procedure parameters (fluoroscopy time, contrast agent volume, radiation dose) of group "ruler" were compared to both other groups by Kruskal-Wallis rank-sum test. RESULTS: Correlation of CT/MRI-derived and fluoroscopy-derived RRV-RAV-distances was good (r = 0.74;p = 0.003). The median RRV-RAV-distance was 4.5cm at CT/MRI (95%-CI:4.2-5.0cm) and 4.0cm at fluoroscopy (95%-CI:3.8-4.5cm). Fluoroscopy time (p<0.0001), contrast agent exposure (p = 0.0003) and radiation dose (air kerma and dose area product both p = 0.038) were significantly lower in group "ruler" compared to group "no ruler" (all p<0.05), and similar to group "expert" (all p>0.05). CONCLUSIONS: CT/MRI-derived pre-interventional renal-adrenal vein distance measurements correlate well with angiographic distance measurements. Pre-interventional estimation of the RRV-RAV-distance allows for aimed cannulation of the RAV with potential reduction of fluoroscopy time, contrast agent exposure and radiation-dose during AVS.

Radiation dose reduction during adrenal vein sampling using a new angiographic imaging technology.

To compare the patient radiation doses during angiographic selective adrenal vein sampling (AVS) before and after an imaging technology upgrade. In this retrospective single-center-study, cumulative air kerma (AK), cumulative dose area product (DAP), fluoroscopy time and contrast agent dosage were recorded from 70 patients during AVS. 35 procedures were performed before and 35 after an imaging processing technology upgrade. Mean values were calculated and compared using an unpaired student's t-test. DSA image quality was assessed independently by two blinded readers using a four-point Likert scale (1 = poor; 4 = excellent) and compared using Wilcoxon signed-rank test. After the technology upgrade we observed a significant reduction of 35% in AK (1.7 ± 0.7 vs. 1.1 ± 0.7 Gy, p = 0.01) and a significant reduction of 28% in DAP (235.1 ± 113 vs. 170.1 ± 94 Gy*cm2, p = 0.01) in comparison to procedures before the upgrade. There were no significant differences between the number of exposure frames (143 ± 86 vs. 132 ± 61 frames, p = 0.53), fluoroscopy time (42 ± 23 vs. 36 ± 18 min, p = 0.22), or the amount of contrast medium used (179.5 ± 84 vs. 198.1 ± 109 ml, p = 0.41). There was also no significant difference regarding image quality (3 (2-4) vs. 3 (2-4), p = 0.67). The angiographic imaging technology upgrade significantly decreases the radiation dose during adrenal vein sampling without increasing time of fluoroscopy or contrast volume and without compromising image quality.

Magnetic resonance angiography derived predictors of progressive dilatation and surgery of the aortic root in Marfan syndrome.

BACKGROUND: To identify magnetic resonance (MR) angiography derived predictors of progressive dilatation and surgery of the aortic root in Marfan syndrome. MATERIAL AND METHODS: We retrospectively included 111 patients (32.7±16.5 years, range: 7-75 years) with a total of 446 MR angiographies. Aortic diameter growth rates of the entire thoracic aorta and Z-scores were estimated from annual diameter measurements. Aortic root shape was subdivided into three different types: (T0) normal; (T1) localized dilatation; (T2) generalized aortic root dilatation. Aortic diameter, Z-score, age, and aortic root shape at baseline were tested as predictors of aortic root dilatation using a multivariate logistic regression model. RESULTS: The highest aortic growth rate was observed at the level of the sinuses of Valsalva. Higher aortic root diameters and Z-scores at baseline predicted an increased growth of the aortic root (p = 0.003 and p<0.001). Young age (<30 years) was a predictor for the increase of Z-scores when compared to patients ≥30 years (p = 0.019). 25/111 patients (22.5%) had a T0 aortic root shape, 59/111 patients (53.2%) had a T1 aortic root shape, and 27/111 patients (24.3%) had a T2 aortic root shape. Aortic root shape did not predict further aortic growth (p>0.05). However, significantly more patients undergoing surgery had a generalized aortic dilatation (19/28, 76.9%) than a localized aortic root dilatation (9/28, 32.1%) (p = 0.001). CONCLUSION: Larger baseline aortic root diameter and Z-score as well as young age predict solely progressive aortic root dilatation in Marfan patients. MR angiography derived type of aortic root shape does not predict aortic growth, but patients with generalized aortic root dilatation are referred more frequently for aortic surgery.

Impact of glyphosate-based herbicide on early embryonic development of the amphibian Xenopus laevis.

BACKGROUND: Worldwide, amphibian populations are declining drastically. One reason might be the use of pesticides including herbicides. The herbicide glyphosate is an inhibitor of the 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase of the plant shikimate pathway, preventing the formation of aromatic amino acids and thus inducing plant death. Due to this specific action, GBH are considered nontoxic to non-target organisms. However, GBH impairs embryonic development of chickens, amphibians and fishes. So far, no detailed tissue- and organ-specific analysis of the effects of GBH during development in amphibians has been performed. RESULTS: We demonstrated that GBH Roundup® LB plus has a negative effect on embryonic development of the South African clawed frog Xenopus laevis. GBH treatment with sublethal concentrations resulted in a reduced body length and mobility of embryos. Furthermore, incubation with GBH led to smaller eyes, brains and cranial cartilages in comparison to untreated embryos. GBH incubation also resulted in shorter cranial nerves and had an effect on cardiac development including reduced heart rate and atrium size. On a molecular basis, GBH treatment led to reduced expression of marker genes in different tissues and developmental stages. CONCLUSION: GBH leads to disturbed embryonic development of Xenopus laevis.

Intraindividual comparison of 1.5 T and 3 T non-contrast MR angiography for monitoring of aortic root diameters in Marfan patients.

BACKGROUND: Reproducible aortic diameter measurements are crucial for assessment of aortic growth and aneurysm formation in patients with Marfan syndrome. The objective of this study was to perform an intraindividual comparison of aortic measurements at 1.5 T and 3 T using non-contrast magnetic resonance angiography (MRA) in pre-surgical and post-surgical Marfan patients. METHODS: Forty consecutive Marfan patients were retrospectively evaluated by ECG-gated 2D balanced steady-state free precession (bSSFP) MRA at 1.5 T and 3 T after 363 ± 58 days. 24 patients were before and 16 patients after aortic root surgery. Two readers independently measured aortic diameters at seven aortic levels and rated the image quality/image artifacts (1 = poor/severe, 4 = excellent/none). Contrast-to-noise ratio (CNR) and signal intensity slopes between aortic lumen and vessel walls were semiautomatically determined. RESULTS: In pre-surgical Marfan patients, interobserver agreement of aortic root diameter measurements was significantly higher at 3 T compared to 1.5 T (p < 0.05). In post-surgical Marfan patients, image quality and artifacts were significantly worse at 3 T compared to 1.5 T (p < 0.05). CNR was higher at 3 T compared to 1.5 T at all aortic levels. Significantly steeper slopes of signal intensity curves were observed at 3 T at all aortic levels (p < 0.001). CONCLUSIONS: In pre-surgical Marfan patients, non-contrast MRA provides higher reproducibility of aortic diameter measurements at 3 T compared to 1.5 T. In post-surgical Marfan patients, metallic implants result in significantly worse imaging artifacts and reduced image quality at 3 T compared to 1.5 T. Therefore, we propose to monitor the thoracic aorta with non-contrast MRA at 3 T in pre-surgical Marfan patients and at 1.5 T in post-surgical Marfan patients.

Prognosis of early pre-discharge and late left ventricular dilatation by cardiac magnetic resonance imaging after acute myocardial infarction.

To study the long-term prognosis of early pre-discharge and late left ventricular (LV) dilatation in patients with first ST-elevation myocardial infarction (STEMI) treated by percutaneous coronary intervention (PCI) and contemporary medical therapy. Long-term follow-up > 15 years was available in 53 consecutive patients (55 ± 13 years) with first STEMI. Late gadolinium enhanced (LGE) cardiac magnetic resonance imaging (CMR) was obtained at baseline 5 ± 3 days and follow-up 8 ± 3 months after STEMI to measure LV function, volumes and infarct size. Early pre-discharge dilatation was defined as increased left ventricular end-diastolic volume index (LVEDVi) at baseline CMR with > 97 ml/m2 for males and > 90 ml/m2 for females. Late dilatation was defined as initially normal LVEDVi, which increased ≥ 20% at follow-up. Early dilatation was present in 7 patients (13%), whereas late dilatation occurred in 11 patients (21%). Patients with early LV dilatation had highest mortality (57%), whereas patients with late dilatation had similar mortality (27%) compared to patients without dilatation (26%). Multivariate Cox analysis showed that age (P < 0.001), ejection fraction at baseline (P < 0.01) and early dilatation (P < 0.01) were independent predictors of death. Early dilatation qualified as an exclusive independent predictor of long-term mortality after adjustment for age and ejection fraction (P < 0.05, hazard ratio: 2.2, 95% confidence interval: 1.2 to 7.9). Early pre-discharge LV dilatation by CMR enabled strong long-term risk stratification after STEMI. The high mortality of early LV dilatation underscores the clinical importance of this post-infarction complication, which occurred despite PCI and contemporary medical therapy.

Abdominal Applications of 4D Flow MRI.

BACKGROUND: Four-dimensional flow magnetic resonance imaging (4D flow MRI) provides volumetric and time-resolved visualization and quantification of blood flow. This review presents an overview of possible applications of 4D flow MRI for non-invasive assessment of abdominal hemodynamics. METHOD: This review is based on the authors' experience and the current literature. A PubMed database literature research was performed in December 2019 focusing on abdominal applications of 4D flow MRI. We illustrated the review with exemplary figures and movies of clinical cases from our institution. RESULTS AND CONCLUSION: 4D flow MRI offers the possibility of comprehensive assessment of abdominal blood flows in different vascular territories and organ systems. Results of recent studies indicate that 4D flow MRI improves understanding of altered hemodynamics in patients with abdominal disease and may be useful for monitoring therapeutic response. Future studies with larger cohorts aiming to integrate 4D flow MRI in the clinical routine setting are needed. KEY POINTS: · 4D flow MRI enables comprehensive visualization of the complex abdominal vasculature. · 4D flow MRI enables quantification of abdominal blood flow velocities and flow rates. · 4D flow MRI may enable deeper understanding of altered hemodynamics in abdominal disease. · Further validation studies are needed prior to broad distribution of abdominal 4D flow MRI. CITATION FORMAT: · Riedel C, Lenz A, Fischer L et al. Abdominal Applications of 4D Flow MRI. Fortschr Röntgenstr 2021; 193: 388 - 398.

Changes in transvalvular flow patterns after aortic valve repair: comparison of symmetric versus asymmetric aortic valve geometry.

OBJECTIVES: The aim of this study was to compare the effect of asymmetric versus symmetric bicuspid aortic valve (BAV) repair on transvalvular flow patterns and aortic wall shear stress (WSS). METHODS: Four-dimensional flow magnetic resonance imaging was prospectively and consecutively performed in patients with congenital aortic valve (AV) disease before and after AV repair. The following MRI-based parameters were assessed: (i) flow eccentricity index, (ii) backward flow across the AV, (iii) grading of vortical and helical flow, and (iv) WSS (N/m2) in the proximal aorta. MRI-derived flow parameters were compared between patients who underwent 'asymmetric BAV repair' (n = 13) and 'symmetric BAV repair' (n = 7). RESULTS: A total of 20 patients (39 ± 12 years, 80% male), who underwent BAV repair, were included. In the asymmetric BAV repair group, circumferential WSS reduction was found at the level of the aortic arch (P = 0.015). In the symmetric BAV repair group, postoperative circumferential WSS was significantly reduced compared to baseline at all levels of the proximal aorta (all P < 0.05). Postoperative circumferential WSS was significantly higher in the asymmetric versus symmetric BAV repair group at the level of the sinotubular junction (0.45 ± 0.15 vs 0.30 ± 0.09 N/m2; P = 0.028), ascending aorta (0.59 ± 0.19 vs 0.44 ± 0.08 N/m2; P = 0.021) and aortic arch (0.59 ± 0.25 vs 0.40 ± 0.08 N/m2; P = 0.017). Segmental WSS analysis showed significantly higher postoperative WSS after asymmetric versus symmetric BAV repair, especially in the anterior aortic segment (P = 0.004). CONCLUSIONS: Symmetric BAV repair results in more physiological flow patterns and significantly reduces WSS, as compared to asymmetric BAV repair. From a haemodynamic point of view, symmetric AV geometry should be attempted in every congenital AV repair.