Sustained Increase in Serum Glial Fibrillary Acidic Protein after First ST-Elevation Myocardial Infarction.

Acute ischemic cardiac injury predisposes one to cognitive impairment, dementia, and depression. Pathophysiologically, recent positron emission tomography data suggest astroglial activation after experimental myocardial infarction (MI). We analyzed peripheral surrogate markers of glial (and neuronal) damage serially within 12 months after the first ST-elevation MI (STEMI). Serum levels of glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) were quantified using ultra-sensitive molecular immunoassays. Sufficient biomaterial was available from 45 STEMI patients (aged 28 to 78 years, median 56 years, 11% female). The median (quartiles) of GFAP was 63.8 (47.0, 89.9) pg/mL and of NfL 10.6 (7.2, 14.8) pg/mL at study entry 0-4 days after STEMI. GFAP after STEMI increased in the first 3 months, with a median change of +7.8 (0.4, 19.4) pg/mL (p = 0.007). It remained elevated without further relevant increases after 6 months (+11.7 (0.6, 23.5) pg/mL; p = 0.015), and 12 months (+10.3 (1.5, 22.7) pg/mL; p = 0.010) compared to the baseline. Larger relative infarction size was associated with a higher increase in GFAP (ρ = 0.41; p = 0.009). In contrast, NfL remained unaltered in the course of one year. Our findings support the idea of central nervous system involvement after MI, with GFAP as a potential peripheral biomarker of chronic glial damage as one pathophysiologic pathway.

B0 shimming of the human heart at 7T.

PURPOSE: Inhomogeneities of the static magnetic B0 field are a major limiting factor in cardiac MRI at ultrahigh field (≥ 7T), as they result in signal loss and image distortions. Different magnetic susceptibilities of the myocardium and surrounding tissue in combination with cardiac motion lead to strong spatio-temporal B0 -field inhomogeneities, and their homogenization (B0 shimming) is a prerequisite. Limitations of state-of-the-art shimming are described, regional B0 variations are measured, and a methodology for spherical harmonics shimming of the B0 field within the human myocardium is proposed. METHODS: The spatial B0 -field distribution in the heart was analyzed as well as temporal B0 -field variations in the myocardium over the cardiac cycle. Different shim region-of-interest selections were compared, and hardware limitations of spherical harmonics B0 shimming were evaluated by calibration-based B0 -field modeling. The role of third-order spherical harmonics terms was analyzed as well as potential benefits from cardiac phase-specific shimming. RESULTS: The strongest B0 -field inhomogeneities were observed in localized spots within the left-ventricular and right-ventricular myocardium and varied between systolic and diastolic cardiac phases. An anatomy-driven shim region-of-interest selection allowed for improved B0 -field homogeneity compared with a standard shim region-of-interest cuboid. Third-order spherical harmonics terms were demonstrated to be beneficial for shimming of these myocardial B0 -field inhomogeneities. Initial results from the in vivo implementation of a potential shim strategy were obtained. Simulated cardiac phase-specific shimming was performed, and a shim term-by-term analysis revealed periodic variations of required currents. CONCLUSION: Challenges in state-of-the-art B0 shimming of the human heart at 7 T were described. Cardiac phase-specific shimming strategies were found to be superior to vendor-supplied shimming.

Twin robotic x-ray system in small bone and joint trauma: impact of cone-beam computed tomography on treatment decisions.

OBJECTIVES: Trauma evaluation of extremities can be challenging in conventional radiography. A multi-use x-ray system with cone-beam CT (CBCT) option facilitates ancillary 3-D imaging without repositioning. We assessed the clinical value of CBCT scans by analyzing the influence of additional findings on therapy. METHODS: Ninety-two patients underwent radiography and subsequent CBCT imaging with the twin robotic scanner (76 wrist/hand/finger and 16 ankle/foot/toe trauma scans). Reports by on-call radiologists before and after CBCT were compared regarding fracture detection, joint affliction, comminuted injuries, and diagnostic confidence. An orthopedic surgeon recommended therapy based on reported findings. Surgical reports (N = 52) and clinical follow-up (N = 85) were used as reference standard. RESULTS: CBCT detected more fractures (83/64 of 85), joint involvements (69/53 of 71), and multi-fragment situations (68/50 of 70) than radiography (all p < 0.001). Six fractures suspected in radiographs were ruled out by CBCT. Treatment changes based on additional information from CBCT were recommended in 29 patients (31.5%). While agreement between advised therapy before CBCT and actual treatment was moderate (κ = 0.41 [95% confidence interval 0.35-0.47]; p < 0.001), agreement after CBCT was almost perfect (κ = 0.88 [0.83-0.93]; p < 0.001). Diagnostic confidence increased considerably for CBCT studies (p < 0.001). Median effective dose for CBCT was 4.3 µSv [3.3-5.3 µSv] compared to 0.2 µSv [0.1-0.2 µSv] for radiography. CONCLUSIONS: CBCT provides advantages for the evaluation of acute small bone and joint trauma by detecting and excluding extremity fractures and fracture-related findings more reliably than radiographs. Additional findings induced therapy change in one third of patients, suggesting substantial clinical impact. KEY POINTS: • With cone-beam CT, extremity fractures and fracture-related findings can be detected and ruled out more reliably than with conventional radiography. • Additional diagnostic information provided by cone-beam CT scans has substantial impact on therapy in small bone and joint trauma. • For distal extremity injury assessment, one-stop-shop imaging without repositioning is feasible with the twin robotic x-ray system.

Twin Robotic X-Ray System for 3D Cone-Beam CT of the Wrist: An Evaluation of Image Quality and Radiation Dose.

OBJECTIVE. The purpose of this study was to assess image quality and radiation dose of a novel twin robotic x-ray system's 3D cone-beam CT (CBCT) function for the depiction of cadaveric wrists. MATERIALS AND METHODS. Sixteen cadaveric wrists were scanned using dedicated low-dose and standard-dose CBCT protocols as well as clinical MDCT for comparison. Three readers assessed overall image quality, noise, and artifacts in bone and soft tissue on 5-point Likert scales. For radiation dose analysis, volume CT dose indexes (CTDIvol) were compared. RESULTS. Overall image quality of most studies was very good or excellent in MDCT (for readers 1, 2, and 3: 100%, 100%, and 88%, respectively), standard-dose CBCT (100%, 100%, and 94%), and low dose CBCT (100%, 94%, and 88%) with two readers favoring standard-dose CBCT over MDCT image quality (readers 1 and 2; p ≤ 0.046). In soft tissue, standard-dose (readers 1, 2, and 3; p ≤ 0.021) and low-dose (all p ≤ 0.001) CBCT images had more noise than MDCT in all cases. Standard-dose (all p ≤ 0.003) and low-dose (all p < 0.001) CBCT images also displayed more artifacts. In osseous tissue, one reader observed more noise (p < 0.001) and artifacts (p = 0.020) for low-dose CBCT than for MDCT, whereas no difference was found between standard-dose CBCT and MDCT. Mean CTDIvol was significantly lower for standard-dose (5.2 ± 0.6 mGy; p < 0.001) and low-dose CBCT (1.8 ± 0.2 mGy; p < 0.001) than for clinical MDCT without automatic dose modulation (15.0 ± 0.0 mGy). CONCLUSION. The tested CBCT function delivers suitable image quality for clinical wrist imaging at significantly lower radiation levels than conventional MDCT. In combination with comfortable positioning options and the ability to perform additional radiographic and fluoroscopic examinations, the twin robotic x-ray system may hold the potential to be a one-stop shop device for trauma-associated wrist imaging.

The importance of radial multiplanar reconstructions for assessment of triangular fibrocartilage complex injury in CT arthrography of the wrist.

BACKGROUND: Triangular fibrocartilage complex (TFCC) lesions commonly cause ulnar-sided wrist pain and instability of the distal radioulnar joint. Due to its triangular shape, discontinuity of the TFCC is oftentimes difficult to visualize in radiological standard planes. Radial multiplanar reconstructions (MPR) may have the potential to simplify diagnosis in CT wrist arthrography. The objective of this study was to assess diagnostic advantages provided by radial MPR over standard planes for TFCC lesions in CT arthrography. METHODS: One hundred six patients (49 women, 57 men; mean age 44.2 ± 15.8 years) underwent CT imaging after wrist arthrography. Two radiologists (R1, R2) retrospectively analyzed three randomized datasets for each CT arthrography. One set contained axial, coronal and sagittal planes (MPRStandard), while the other two included an additional radial reconstruction with the rotating center either atop the ulnar styloid (MPRStyloid) or in the ulnar fovea (MPRFovea). Readers evaluated TFCC differentiability and condition. Suspected lesions were categorized using Palmer's and Atzei's classification and diagnostic confidence was stated on a five-point Likert scale. RESULTS: Compared to standard planes, differentiability of the superficial and deep TFCC layer was superior in radial reconstructions (R1/R2; MPRFovea: p < 0.001; MPRStyloid: p ≤ 0.007). Palmer and Atzei lesions were present in 86.8% (92/106) and 52.8% (56/106) of patients, respectively. Specificity, sensitivity and accuracy for central Palmer lesions did not differ in radial and standard MPR. For peripheral Atzei lesions, sensitivity (MPRStandard 78.6%/80.4%, MPRStyloid 94.6%/94.6%, MPRFovea 91.1%/89.3%) and accuracy (MPRStandard 86.8%/86.8%, MPRStyloid 96.2%/96.2%, MPRFovea 94.3%/93.4%) improved with additional styloid-centered (p = 0.004/0.008) and fovea-centered (p = 0.039/0.125) reconstructions. No substantial difference was observed between both radial MPR (p = 0.688/0.250). Interrater agreement was almost perfect for each dataset (κStandard = 0.876, κStyloid = 0.894, κFovea = 0.949). Diagnostic confidence increased with addition of either radial MPR (p < 0.001). CONCLUSIONS: Ancillary radial planes improve accuracy and diagnostic confidence for detection of peripheral TFCC lesions in CT arthrography of the wrist.

Radiation dose of coronary CT angiography with a third-generation dual-source CT in a "real-world" patient population.

OBJECTIVES: To assess radiation dose and image quality of coronary computed tomography angiography (cCTA) with a third-generation dual-source scanner in a real-world patient population. METHODS: Scans of otherwise unselected, consecutive patients referred for clinically indicated cCTA between June 2015 and November 2017 were included for retrospective analysis. Scan protocol was based on heart rate: prospectively ECG-gated high-pitch spiral below 60 beats per minute (bpm), prospectively ECG-gated sequential scan between 61 and 70 bpm, and retrospective spiral above 70 bmp or at irregular heart rates. Objective image quality was measured as signal-to-noise (SNR) and contrast-to-noise ratio (CNR); subjective image quality was evaluated using a five-point Likert scale by two independent readers. For radiation dose analysis, effective dose, size-specific dose estimates, and volume CT dose index were assessed. RESULTS: Two hundred seventy-eight patients (median age, 60 years; 155 men) with a median body mass index of 26.6 kg/m2 (range, 16.7-60.9 kg/m2; 180 (64.7%) overweight or obese) were included (122 in the high-pitch spiral group, 60 in the prospective sequence group, and 96 in the retrospective spiral group). Median effective dose was 0.63 mSv (interquartile range [IQR], 0.51-0.90 mSv) for high-pitch spiral, 1.32 mSv (IQR, 0.79-2.46 mSv) for prospective sequence, and 4.77 (IQR, 3.02-8.27 mSv) for retrospective spiral (p < 0.001). Most studies had at least very good image quality (91.4/88.8% R1/R2), with highest SNR and CNR in the high-pitch spiral group. CONCLUSIONS: cCTA with sufficient image quality is achievable at reasonably low radiation exposure in a real-world patient collective with a high proportion of overweight or obese patients. KEY POINTS: • Submillisievert radiation dose coronary CT angiography with good diagnostic image quality is feasible in the majority of cases in a real-world patient using high-pitch spiral. • Prospective sequence results in about double median effective dose compared to the high-pitch protocol. • To optimize individual radiation exposure, lowering the heart rate is paramount, as it allows for choosing a dose-optimized (high-pitch spiral) scan protocol.

"Blind" pericardiocentesis: A comparison of different puncture directions.

BACKGROUND: "Blind" pericardiocentesis is the standard procedure for emergency pericardial drainage when ultrasound guidance is unavailable. Under these circumstances, puncture site and needle direction are exclusively oriented according to certain anatomic landmarks. In the literature, different techniques for this "blind" method have been described. Goal of this retrospective study was to compare the potential success and complication rate of 13 simulated puncture directions. METHODS: Simulated pericardiocentesis was performed in 150 CT scans from patients with moderate to severe pericardial effusions (greater than 1 cm distance between epicardium and pericardium). Thirteen different puncture techniques with varying puncture sites, direction of the puncture, and the angle were compared. A simulated pericardiocentesis was classified as "successful" when the effusion was reached. It was classified as "successful without a complication" when no adjacent structure was penetrated by the simulated puncture (lung, liver, internal thoracic artery, LAD, colon, and stomach). An attempt was declared as "unsuccessful" when the pericardial effusion was not reached at all, or the reached effusion measured less than 0.5 cm between the epicardium and pericardium at the location where the needle entered the pericardium. RESULTS: A subxiphoidal puncture technique starting in Larrey's triangle (sternocostal triangle) and directed toward the left midclavicular point with a 30° inclination resulted in the highest success rate (131 of 150 cases = 87%). In parallel the lowest complication rate (7 of 150 = 5%) was found using this technique, as well. In contrast, pericardiocentesis performed using other puncture directions resulted in lower success (66%-85%) and higher complication rates (9%-31%). CONCLUSION: This CT-based simulation study revealed that blind pericardiocentesis guided by anatomical landmarks only is best performed in a subxiphoid approach with a needle direction to the left midclavicular point with a 30° inclination. Nevertheless, injury of adjacent structures occurred frequently (5%) even when applying this puncture technique. Thus, blind pericardiocentesis can be performed with a high success rate and seems adequate to be performed under emergency conditions. However, planned procedures should be performed under image guidance.

Vertebral Compression Fractures: Third-Generation Dual-Energy CT for Detection of Bone Marrow Edema at Visual and Quantitative Analyses.

Purpose To assess the diagnostic performance of a third-generation dual-energy computed tomographic (CT) virtual noncalcium (VNCa) technique for detection of traumatic bone marrow edema in patients with vertebral compression fractures. Materials and Methods This prospective study was approved by the institutional review board. Informed consent was obtained from all participants. Twenty-two consecutive patients with 37 morphologic vertebral fractures were studied between October 2015 and May 2016. All patients underwent dual-energy CT (90 kV and 150 kV with a tin filter) and 3-T magnetic resonance (MR) imaging. Two independent readers visually evaluated all vertebral bodies (n = 163) for the presence of abnormal bone marrow attenuation on VNCa images by using color-coded maps and performed a quantitative analysis of CT numbers on VNCa images. MR images served as the reference standard. CT numbers were subjected to receiver operating characteristic analysis to calculate cutoff values. Results In the visual analysis, VNCa images had an overall sensitivity of 64.0%, specificity of 99.3%, accuracy of 93.9%, positive predictive value of 94.1%, and negative predictive value of 93.8%. The interobserver agreement was excellent (κ = 0.85). CT numbers obtained from VNCa images were significantly different in vertebral bodies with and without edema (P < .001). Receiver operating characteristic analysis revealed an area under the curve of 0.922. A cutoff value of -47 provided sensitivity of 92.0%, specificity of 82.6%, accuracy of 84.0%, positive predictive value of 48.9%, and negative predictive value of 98.3% for the differentiation of edematous vertebral bodies. Conclusion Visual and quantitative analyses of dual-energy VNCa images showed excellent diagnostic performance for assessing traumatic bone marrow edema in vertebral compression fractures. © RSNA, 2017 Online supplemental material is available for this article.

Contrast-enhanced voiding urosonography phantom study: intravenous iodinated and gadolinium-based contrast agents may cause false-negative results in assessment of vesicoureteral reflux in children.

BACKGROUND: Contrast-enhanced voiding urosonography (ce-VUS) is commonly requested simultaneously to other diagnostic imaging necessitating intravenous contrast agents. To date there is limited knowldedge about intravesical interactions between different types of contrast agents. OBJECTIVE: To assess the effect of excreted intravenous iodinated and gadolinium-based contrast agents on the intravesical distribution of ultrasound contrast within contrast-enhanced voiding urosonography. MATERIALS AND METHODS: Iodinated (iomeprol, iopamidol) and gadolinium-based (gadoterate meglumine) contrast agents were diluted to bladder concentration and injected into balloons filled with saline solution. CT scans were performed to assess the contrast distribution in these phantoms. Regions of interest were placed at the top and bottom side of each balloon and Hounsfield units (HU) were measured. Three other balloons were filled with saline solution and contrast media likewise. The ultrasound contrast agent sulphur hexafluoride was added and its distribution was assessed using sonography. RESULTS: MDCT scans showed a separation of two liquid layers in all bladder phantoms with the contrast layers located at the bottom and the saline solution at the top. Significant differences of the HU measurements at the top and bottom side were observed (P < 0.001-0.007). Following injection of ultrasound contrast agent, US showed its distribution exclusively among the saline solution. CONCLUSIONS: False-negative results of contrast-enhanced voiding urosonography may occur if it is performed shortly after imaging procedures requiring intravenous contrast.

Next generation coronary CT angiography: in vitro evaluation of 27 coronary stents.

OBJECTIVES: To evaluate in-stent lumen visibility of 27 modern and commonly used coronary stents (16 individual stent types, two stents at six different sizes each) utilising a third-generation dual-source CT system. METHODS: Stents were implanted in a plastic tube filled with contrast. Examinations were performed parallel to the system's z-axis for all stents (i.e. 0°) and in an orientation of 90° for stents with a diameter of 3.0 mm. Two stents were evaluated in different diameters (2.25 to 4.0 mm). Examinations were acquired with a collimation of 96 × 0.6 mm, tube voltage of 120 kVp with 340 mAs tube current. Evaluation was performed using a medium-soft (Bv40), a medium-sharp (Bv49) and a sharp (Bv59) convolution kernel optimised for vascular imaging. RESULTS: Mean visible stent lumen of stents with 3.0 mm diameter ranged from 53.3 % (IQR 48.9 - 56.7 %) to 73.9 % (66.7 - 76.7 %), depending on the kernel used at 0°, and was highest at an orientation of 90° with 80.0 % (75.6 - 82.8 %) using the Bv59 kernel, strength 4. Visible stent lumen declined with decreasing stent size. CONCLUSIONS: Use of third-generation dual-source CT enables stent lumen visibility of up to 80 % in metal stents and 100 % in bioresorbable stents. KEY POINTS: • Blooming artefacts impair in-stent lumen visibility of coronary stents in CT angiography. • CT enables stent lumen visibility of up to 80 % in metal stents. • Stent lumen visibility varies with stent orientation and size. • CT angiography may be a valid alternative for detecting in-stent restenosis.

Partial segmental thrombosis of the corpus cavernosum (PSTCC) diagnosed by contrast-enhanced ultrasound: a case report.

BACKGROUND: Partial segmental thrombosis of the corpus cavernosum (PSTCC) is a rare disease predominantly occurring in young men. Cardinal symptoms are pain and perineal swelling. Although several risk factors are described in the literature, the exact etiology of penile thrombosis remains unclear in most cases. MRI or ultrasound (US) is usually used for diagnosing this condition. CASE PRESENTATION: We report a case of penile thrombosis after left-sided varicocele ligature in a young patient. The diagnosis was established using contrast-enhanced ultrasound (CEUS) and was confirmed by contrast-enhanced magnetic resonance imaging (ceMRI). Successful conservative treatment consisted of systemic anticoagulation using low molecular weight heparin and acetylsalicylic acid. CONCLUSION: PSTCC is a rare condition in young men and appears with massive pain and perineal swelling. In case of suspected PSTCC utilization of CEUS may be of diagnostic benefit.

Use of serial changes in biomarkers vs. baseline levels to predict left ventricular remodelling after STEMI.

AIMS: Cellular communication network factor 1 (CCN1) is an independent predictor of MACE after ACS and elevated levels correlated with infarct size after STEMI. We compared the prognostic accuracy of baseline levels of CCN1, NT-proBNP, hsTnT, and ST2 and changes in levels over time to predict the development of structural and functional alterations typical of LV remodelling. METHODS: Serial 3-T cMRI scans were performed to determine LVEF, LVEDV, LVESV, infarct size, and relative infarct size, which were correlated with serial measurements of the four biomarkers. The prognostic significance of these biomarkers was assessed by multiple logistic regression analysis by examining their performance in predicting dichotomized cardiac MRI values 12 months after STEMI based on their median. For each biomarker three models were created using baseline (BL), the Δ value (BL to 6 months), and the two values together as predictors. All models were adjusted for age and renal function. Receiver operator curves were plotted with area under the curve (AUC) to discriminate the prognostic accuracy of individual biomarkers for MRI-based structural or functional changes. RESULTS: A total of 44 predominantly male patients (88.6%) from the ETiCS (Etiology, Titre-Course, and Survival) study were identified at a mean age of 55.5 ± 11.5 (SD) years treated by successful percutaneous coronary intervention (97.7%) at a rate of 95.5% stent implantation within a median pain-to-balloon time of 260 min (IQR 124-591). Biomarkers hsTnT and ST2 were identified as strong predictors (AUC > 0.7) of LVEDV and LVEF. BL measurement to predict LVEF [hsTnT: AUC 0.870 (95% CI: 0.756-0.983), ST2: AUC 0.763 (95% CI: 0.615-0.911)] and the Δ value BL-6M [hsTnT: AUC 0.870 (95% CI: 0.756-0.983), ST2: AUC 0.809 (95% CI: 0.679-0.939)] showed a high prognostic value without a significant difference for the comparison of the BL model vs. the Δ-value model (BL-6M) for hsTnT (P = 1) and ST2 (P = 0.304). The combined model that included baseline and Δ value as predictors was not able to improve the ability to predict LVEF [hsTnT: AUC 0.891 (0.791-0.992), P = 0.444; ST2: AUC 0.778 (0.638-0.918), P = 0.799]. Baseline levels of CCN1 were closely associated with LVEDV at 12 months [AUC 0.708 (95% CI: 0.551-0.865)] and infarct size [AUC 0.703 (95% CI: 0.534-0.872)]. CONCLUSIONS: Baseline biomarker levels of hsTnT and ST2 were the strongest predictors of LVEF and LVEDV at 12 months after STEMI. The association of CCN1 with LVEDV and infarct size warrants further study into the underlying pathophysiology of this novel biomarker.

Features of metabolic syndrome and inflammation independently affect left ventricular function early after first myocardial infarction.

BACKGROUND: A high body mass index (BMI) is often associated with metabolic syndrome, which is accompanied by systemic low-grade chronic inflammation. Here, we analyzed whether BMI, other components of metabolic syndrome, and/or inflammatory markers correlate with left ventricular geometry, function, and infarct size as assessed by serial cardiac magnetic resonance imaging (MRI) after a first (clinically evident) ST-elevation MI (STEMI). METHODS: Within the Etiology, Titre-Course, and effect on Survival (ETiCS) study, cardiac MRI conducted 7-9 days and 12 months after MI enabled longitudinal characterization of patients with a first STEMI along with serial routine blood counts and multiplex cytokine measurements. RESULTS: Of 91 locally included STEMI patients, 47% were overweight (25 kg/m2 < BMI < 30 kg/m2) and 24% were obese (BMI ≥ 30 kg/m2). No patient died during 12 months of follow-up. Left ventricular ejection fraction (LVEF), measured 7-9 days after STEMI, was significantly lower in overweight (49.5 ± 7.1%) and obese (45.8 ± 12.0%) patients than in the normal weight group (56.2 ± 7.7%). Along with BMI (T = -3.8; p < 0.001), hemoglobin A1c (HbA1c; T = -3.1; p = 0.004) and peak C-reactive protein (T = -2.6; p = 0.013) emerged as independent predictors of worse LVEF 7-9 days post MI (R2 = 0.45). Only peak C-reactive protein (T = -4.4; p < 0.001), but not parameters of the metabolic syndrome, predicted worse LVEF 12 months after STEMI (R2 = 0.20). CONCLUSION: Both BMI and HbA1c correlated negatively with LVEF only early, but not late after STEMI. Peak CRP evolved as strongest predictor of cardiac function at all time points independent of the metabolic syndrome.

Ultra-high field cardiac MRI in large animals and humans for translational cardiovascular research.

A key step in translational cardiovascular research is the use of large animal models to better understand normal and abnormal physiology, to test drugs or interventions, or to perform studies which would be considered unethical in human subjects. Ultrahigh field magnetic resonance imaging (UHF-MRI) at 7 T field strength is becoming increasingly available for imaging of the heart and, when compared to clinically established field strengths, promises better image quality and image information content, more precise functional analysis, potentially new image contrasts, and as all in-vivo imaging techniques, a reduction of the number of animals per study because of the possibility to scan every animal repeatedly. We present here a solution to the dual use problem of whole-body UHF-MRI systems, which are typically installed in clinical environments, to both UHF-MRI in large animals and humans. Moreover, we provide evidence that in such a research infrastructure UHF-MRI, and ideally combined with a standard small-bore UHF-MRI system, can contribute to a variety of spatial scales in translational cardiovascular research: from cardiac organoids, Zebra fish and rodent hearts to large animal models such as pigs and humans. We present pilot data from serial CINE, late gadolinium enhancement, and susceptibility weighted UHF-MRI in a myocardial infarction model over eight weeks. In 14 pigs which were delivered from a breeding facility in a national SARS-CoV-2 hotspot, we found no infection in the incoming pigs. Human scanning using CINE and phase contrast flow measurements provided good image quality of the left and right ventricle. Agreement of functional analysis between CINE and phase contrast MRI was excellent. MRI in arrested hearts or excised vascular tissue for MRI-based histologic imaging, structural imaging of myofiber and vascular smooth muscle cell architecture using high-resolution diffusion tensor imaging, and UHF-MRI for monitoring free radicals as a surrogate for MRI of reactive oxygen species in studies of oxidative stress are demonstrated. We conclude that UHF-MRI has the potential to become an important precision imaging modality in translational cardiovascular research.

Self-configuring nnU-net pipeline enables fully automatic infarct segmentation in late enhancement MRI after myocardial infarction.

PURPOSE: To fully automatically derive quantitative parameters from late gadolinium enhancement (LGE) cardiac MR (CMR) in patients with myocardial infarction and to investigate if phase sensitive or magnitude reconstructions or a combination of both results in best segmentation accuracy. METHODS: In this retrospective single center study, a convolutional neural network with a U-Net architecture with a self-configuring framework ("nnU-net") was trained for segmentation of left ventricular myocardium and infarct zone in LGE-CMR. A database of 170 examinations from 78 patients with history of myocardial infarction was assembled. Separate fitting of the model was performed, using phase sensitive inversion recovery, the magnitude reconstruction or both contrasts as input channels. Manual labelling served as ground truth. In a subset of 10 patients, the performance of the trained models was evaluated and quantitatively compared by determination of the Sørensen-Dice similarity coefficient (DSC) and volumes of the infarct zone compared with the manual ground truth using Pearson's r correlation and Bland-Altman analysis. RESULTS: The model achieved high similarity coefficients for myocardium and scar tissue. No significant difference was observed between using PSIR, magnitude reconstruction or both contrasts as input (PSIR and MAG; mean DSC: 0.83 ±â€¯0.03 for myocardium and 0.72 ±â€¯0.08 for scars). A strong correlation for volumes of infarct zone was observed between manual and model-based approach (r = 0.96), with a significant underestimation of the volumes obtained from the neural network. CONCLUSION: The self-configuring nnU-net achieves predictions with strong agreement compared to manual segmentation, proving the potential as a promising tool to provide fully automatic quantitative evaluation of LGE-CMR.

Photon-Counting Computed Tomography for Coronary Stent Imaging: In Vitro Evaluation of 28 Coronary Stents.

OBJECTIVES: The aim of this study was to assess in-stent lumen visibility and quantitative image characteristics of different coronary stents using a novel photon-counting detector (PCD) computed tomography (CT) system in comparison to a state-of-the-art energy-integrating detector (EID) CT scanner. MATERIALS AND METHODS: In this in vitro phantom study, 28 different coronary stents ranging from 2.25 to 4.5 mm lumen diameter were expanded into plastic tubes filled with contrast agent. Stent-containing plastic tubes were positioned in a custom-made emulsion-filled phantom, which was inserted into an anthropomorphic phantom simulating a medium-sized patient. Computed tomography scans were acquired parallel to the scanners' z axis using a novel cadmium telluride-based PCD CT system (SOMATOM CountPlus; Siemens Healthcare GmbH, Forchheim Germany), operating in 2 different modes (standard-resolution mode [SR] and ultra-high-resolution [UHR] mode), and a latest generation dual-source EID CT system (SOMATOM Force; Siemens Healthcare GmbH, Forchheim). CTDIvol-matched images were reconstructed with comparable convolution kernels and using the same reconstruction parameters. In-stent lumen visibility (in %), increase in in-stent attenuation (expressed as Δ in-stent CT attenuation), and image noise (in Hounsfield unit) were manually measured. Parts of the image analysis (in-stent lumen visibility) were additionally performed in an automated way. Differences were tested using Wilcoxon signed rank test. RESULTS: The best in-stent lumen visibility was achieved with the PCD-UHR mode and the lowest noise levels with the PCD-SR mode. The median in-stent lumen visibility was significantly higher (P < 0.001) with PCD (SR, 66.7%; interquartile range [IQR], 63.3-72.3; UHR, 68.9%; IQR, 64.4-74.4) compared with EID (65.4%; IQR, 62.2-70.4). The Δ in-stent CT attenuation was significantly lower for PCD in both SR (78 HU; IQR, 46-108; P = 0.024) and UHR (85 HU; IQR, 59-113; P = 0.006) compared with EID (108 HU; IQR, 85-126). Image noise was significantly lower (P < 0.001) for PCD-SR (21 HU; IQR, 21-21) compared with EID images (25 HU; IQR, 24-25.0). CONCLUSIONS: The PCD provides superior in-stent lumen visibility and quantitative image characteristics when compared with conventional EID.

Dual-room twin-CT scanner in multiple trauma care: first results after implementation in a level one trauma centre.

PURPOSE: The trauma centre of the Wuerzburg University Hospital has integrated a pioneering dual-room twin-CT scanner in a multiple trauma pathway. For concurrent treatment of two trauma patients, two carbon CT examination and intervention tables are positioned head to head with one sliding CT-Gantry in the middle. The focus of this study is the process of trauma care with the time to CT (tCT) and the time to operation (tOR) as quality indicator. METHODS: All patients with suspected multiple trauma, who required emergency surgery and who were initially diagnosed by the CT trauma protocol between 05/2018 and 12/2018 were included. Data relating to time spans (tCT and tOR), severity of injury and outcome was obtained. RESULTS: 110 of the 589 screened trauma patients had surgery immediately after finishing primary assessment in the ER. The ISS was 17 (9-34) (median and interquartile range, IQR). tCT was 15 (11-19) minutes (median and IQR) and tOR was 96.5 (75-119) minutes (median and IQR). In the first 30 days, seven patients died (6.4%) including two within the first 24 h (2%). There were two ICU days (1-6) (median and IQR) and one (0-1) (median and IQR) ventilator day. CONCLUSION: The twin-CT technology is a fascinating tool to organize high-quality trauma care for two multiple trauma patients simultaneously.

Contrast-enhanced MRI of the wrist: Intravenous application of gadolinium improves diagnosis in ulnar-sided injuries of the TFCC.

PURPOSE: Although lesions of the triangular fibrocartilage complex (TFCC) frequently induce ulnar-sided wrist pain and potentially distal radioulnar joint instability, diagnosis can pose a challenge due to the intricate anatomy. This study aims to evaluate the benefits of contrast-enhanced sequences for the detection of TFCC injuries in magnetic resonance imaging of the wrist. METHOD: 94 patients underwent wrist MRI with intravenous application of gadolinium-based contrast agents. For each patient, two datasets were analysed independently by two board-certified radiologists: One set comprised only plain T1- and fat-saturated proton-density-weighted sequences, while the second dataset included contrast-enhanced T1-weighted images with fat suppression. Arthroscopy or clinical reports served as reference standard with the former being used whenever available. Diagnostic confidence and TFCC component assessability were subjectively evaluated. Contrast-to-noise ratios (CNR) were calculated serve as an objective indicator of image contrast. RESULTS: Lesions of the articular disc, the foveal and styloid ulnar attachment were present in 24 (25.5%), 61 (64.9%) and 53 (56.4%) patients. Access to contrast-enhanced T1 images improved the diagnostic accuracy for injuries of the styloid (R1/R2, 0.68/0.73 vs. 0.86/0.88) and foveal attachment (0.68/0.72 vs. 0.90/0.89) substantially compared to plain MRI (all p < 0.001), while no benefits could be identified for lesions of the central disc (0.89/0.90 vs. 0.87/0.90). Readers' diagnostic confidence and CNR for ulnar-sided lesions improved with contrast-enhanced T1 sequences available (p < 0.001). CONCLUSIONS: With superior CNR in lesions of the TFCC's foveal and styloid attachment, contrast-enhanced, fat-saturated T1-weighted sequences facilitate higher diagnostic accuracy and confidence than fat-saturated PD- and plain T1-weighted MRI.

Dose reduction potential in cone-beam CT imaging of upper extremity joints with a twin robotic x-ray system.

Cone-beam computed tomography is a powerful tool for 3D imaging of the appendicular skeleton, facilitating detailed visualization of bone microarchitecture. This study evaluated various combinations of acquisition and reconstruction parameters for the cone-beam CT mode of a twin robotic x-ray system in cadaveric wrist and elbow scans, aiming to define the best possible trade-off between image quality and radiation dose. Images were acquired with different combinations of tube voltage and tube current-time product, resulting in five scan protocols with varying volume CT dose indices: full-dose (FD; 17.4 mGy), low-dose (LD; 4.5 mGy), ultra-low-dose (ULD; 1.15 mGy), modulated low-dose (mLD; 0.6 mGy) and modulated ultra-low-dose (mULD; 0.29 mGy). Each set of projection data was reconstructed with three convolution kernels (very sharp [Ur77], sharp [Br69], intermediate [Br62]). Five radiologists subjectively assessed the image quality of cortical bone, cancellous bone and soft tissue using seven-point scales. Irrespective of the reconstruction kernel, overall image quality of every FD, LD and ULD scan was deemed suitable for diagnostic use in contrast to mLD (very sharp/sharp/intermediate: 60/55/70%) and mULD (0/3/5%). Superior depiction of cortical and cancellous bone was achieved in FDUr77 and LDUr77 examinations (p < 0.001) with LDUr77 scans also providing favorable bone visualization compared to FDBr69 and FDBr62 (p < 0.001). Fleiss' kappa was 0.618 (0.594-0.641; p < 0.001), indicating substantial interrater reliability. In this study, we demonstrate that considerable dose reduction can be realized while maintaining diagnostic image quality in upper extremity joint scans with the cone-beam CT mode of a twin robotic x-ray system. Application of sharper convolution kernels for image reconstruction facilitates superior display of bone microarchitecture.

Evaluation of Ultra-High-Resolution Cone-Beam CT Prototype of Twin Robotic Radiography System for Cadaveric Wrist Imaging.

RATIONALE AND OBJECTIVES: Cone-beam CT (CBCT) applications possess potential for dose reduction in musculoskeletal imaging. This study evaluates the ultra-high-resolution CBCT prototype of a twin robotic X-ray system in wrist examinations compared to high-resolution multidetector CT (MDCT). MATERIALS AND METHODS: Sixteen wrists of body donors were examined with the CBCT scan mode and a 384 slice MDCT system. Radiation-equivalent low-dose (CTDIvol(16cm)  = 3.3 mGy) and full-dose protocols (CTDIvol(16cm)  = 13.8 mGy) were used for both systems. Two observers assessed image quality on a seven-point Likert scale. In addition, software-assisted quantification of signal intensity fractions in cancellous bone was performed. Fewer pixels with intermediate signal intensity were considered to indicate superior depiction of bone microarchitecture. RESULTS: Subjective image quality in CBCT was superior to dose equivalent MDCT with p ≤ 0.03 for full-dose and p < 0.001 for low-dose scans, respectively. Median Likert values were 7/7 (reader 1 / reader 2) in full-dose CBCT, 6/6 in full-dose MDCT, 5/6 in low-dose CBCT and 3/3 in low-dose MDCT. Intraclass correlation coefficient was 0.936 (95% confidence interval, 0.897-0.961; p < 0.001), indicating excellent reliability. Objective analysis displayed smaller fractions of "indecisive" pixels with intermediate signal intensity for full-dose CBCT (0.57 [interquartile range 0.13]) compared to full-dose MDCT (0.68 [0.21]), low-dose CBCT (0.72 [0.19]), and low-dose MDCT (0.80 [0.15]) studies. No significant difference was observed between low-dose CBCT and full-dose MDCT. CONCLUSION: The new CBCT prototype provides superior image quality for trabecula and bone marrow in cadaveric wrist studies and enables dose reduction up to 75% compared to high-resolution MDCT.