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OBJECTIVES: : Sepsis-associated changes of the arachidonic acid metabolism and the utility of arachidonic acid metabolites for the diagnosis of sepsis have been poorly investigated so far. Therefore, the primary objective of our study was to screen for differentially regulated arachidonic acid metabolites in septic patients using a lipopolysaccharide whole-blood model and to investigate their diagnostic potential. DESIGN: : Prospective, observational, single-center, clinical study. SETTING: : Intensive care unit at University Hospital Leipzig. PATIENTS: : Thirty-five patients (first cohort 25 patients, second cohort 10 patients) meeting the criteria for severe sepsis or septic shock were enrolled. Eighteen healthy volunteers (first cohort 15 subjects, second cohort 3 subjects) were enrolled as controls. INTERVENTIONS: : None. MEASUREMENTS AND MAIN RESULTS: : Arachidonic acid and its metabolites were investigated in supernatants of nonactivated (baseline) and lipopolysaccharide-activated heparinized whole blood of healthy subjects (n = 15) and septic patients (n = 25) by solid phase extraction and subsequent liquid chromatography-tandem mass spectrometry. Arachidonic acid, arachidonic acid analogues, and the cyclooxygenase-associated metabolites prostaglandin E2, 11-hydroxyeicosatetraenoic acid, and thromboxane B2 were identified as differentiating metabolites between septic patients and healthy subjects. Some of these compounds, including arachidonic acid, its analogues, and the cyclooxygenase metabolites prostaglandin E2 and thromboxane B2 differed at baseline. The inducibility of arachidonic acid and the cyclooxygenase metabolites 11-hydroxyeicosatetraenoic and prostaglandin E2 were reduced by 80% to 90% in septic patients. The degree of the inducibility was associated with severity of sepsis and clinical outcome. A reduced inducibility of COX-2 but preserved inducibility of mPGES-1 on gene expression level were confirmed in an independent cohort of septic patients (n = 10) by quantitative reverse-transcription polymerase chain reaction compared to healthy controls (n = 3). CONCLUSIONS: : Arachidonic acid metabolism is markedly affected in patients with sepsis. Our data suggest that the analysis of arachidonic acid metabolites in an in vitro whole blood activation model may be a promising approach for risk estimation in septic patients that has to be further evaluated in subsequent large-scale clinical studies. [ABSTRACT FROM AUTHOR]

Eicosanoids play a key role in many physiological and pathological processes and might therefore serve as interesting diagnostic targets. Methods for the analysis of arachidonic acid metabolites in cells and body fluids require high sensitivity and specificity because of the very low concentrations, similar chemical structures and short half-lives of these metabolites. We established a mass spectrometric method for the simultaneous identification and quantification of arachidonic acid metabolites in human plasma samples using solid phase extraction followed by liquid chromatography (LC) and hybrid triple quadrupole-linear ion trap (QqLIT) mass spectrometry. Quantitative analysis was performed using the 4000 QTrap tandem mass spectrometer in multiple reaction monitoring (MRM) mode. As part of an independent data acquisition experiment MRMs were used as survey scans, which dependently triggered enhanced product ion (EPI) scans. Compound identification was carried out by library search using a library based on EPI spectra of standard components (prostaglandins, thromboxanes, leukotrienes and isoprostanes). The newly developed compound library enables the verification of known and structural elucidation of unknown eicosanoid metabolites in human plasma. In conclusion, our mass spectrometric method allows the simultaneous identification and quantification of arachidonic acid metabolites in one single LC-MS/MS run. [ABSTRACT FROM AUTHOR]

The effect of the steroid hormone progesterone on transepithelial sodium transport was measured in confluent monolayers of the A6-cell line from Xenopus kidney. Apical permeabilization with Amphotericin B enabled us to measure the Na+/K+-pump current, and current-fluctuation analysis was used to analyze changes in apical channel density and gating characteristics. Basolateral progesterone (22.2 µM) had a rapid inhibitory effect on the Na+/K+-pump current, and a corresponding decrease in Na+ channel density. The effect occurred within some minutes and took about 50 min to reach a new steady state, in which 45% of the macroscopic current (Isc) was inhibited. Progesterone also inhibits the hypo-osmotic stimulation of Na+ channels which occurs in untreated monolayers. Compared with the known effects of adrenal steroids, our results show a rapid inhibitory action of a steroid hormone on Na+ absorption. The time profile of the progesterone effect suggests, at least in the first minutes, a non-genomic action of progesterone. [ABSTRACT FROM AUTHOR]

Objectives: The main objective was to develop and evaluate an artificial intelligence model for tooth segmentation in magnetic resonance (MR) scans., Methods: MR scans of 20 patients performed with a commercial 64-channel head coil with a T1-weighted 3D-SPACE (Sampling Perfection with Application Optimized Contrasts using different flip angle Evolution) sequence were included. Sixteen datasets were used for model training and 4 for accuracy evaluation. Two clinicians segmented and annotated the teeth in each dataset. A segmentation model was trained using the nnU-Net framework. The manual reference tooth segmentation and the inferred tooth segmentation were superimposed and compared by computing precision, sensitivity, and Dice-Sørensen coefficient. Surface meshes were extracted from the segmentations, and the distances between points on each mesh and their closest counterparts on the other mesh were computed, of which the mean (average symmetric surface distance) and 95th percentile (Hausdorff distance 95%, HD95) were reported., Results: The model achieved an overall precision of 0.867, a sensitivity of 0.926, a Dice-Sørensen coefficient of 0.895, and a 95% Hausdorff distance of 0.91 mm. The model predictions were less accurate for datasets containing dental restorations due to image artefacts., Conclusions: The current study developed an automated method for tooth segmentation in MR scans with moderate to high effectiveness for scans with respectively without artefacts., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Institute of Radiology and the International Association of Dentomaxillofacial Radiology.)

Background and Purpose: Complicated American Heart Association (AHA) lesion type VI plaques (cCAPs), characterized by the presence of intraplaque hemorrhage, surface defect or thrombus, are strongly associated with ischemic stroke and stroke recurrence. Hemodynamics seem to play a relevant role for their development. Thus, we investigated the association of 4D flow-MRI derived local wall shear stress (WSS) and oscillatory shear stress (OSI) with the presence of cCAPs in patients with mild to moderate internal carotid artery (ICA) stenosis., Materials and Methods: From a prospective and consecutive cross-sectional study with 121 patients with high cardiovascular risk, 39 patients (49 carotid arteries) demonstrated a 10-50% ICA-stenosis and were included in this analysis. Plaque composition was determined according to the modified AHA classification of lesions by high-resolution multi-contrast 3T-MRI. We determined WSS (minimum, mean and maximum) and OSI in vivo by 4D flow-MRI at different locations within the stenosis (upstream, stenosis center and downstream). We studied the association of each hemodynamic parameter with the presence cCAPs by logistic regression analysis adjusted for age, sex and plaque thickness., Results: 11 (22.4%) of the 49 ICA-stenosis in our cohort showed cCAP. WSS and OSI at the beginning of the stenosis did not differ between complicated and stable plaques. By contrast, WSS was significantly higher in the stenosis center and poststenotic region in cCAPs. OSI was significantly higher in the stenosis center of stable plaques. Logistic regression analysis revealed a significant association for WSS mean (OR per SD increase 1.97, 95%-CI 1.14-3.39, p=0.015) and for WSS max (OR per SD increase 1.84; 95%-CI 1.10-3.08; p=0.020), but not for WSS min and OSI with the presence of cCAPs., Conclusions: Higher wall shear stress in ICA stenosis was significantly associated with the presence of cCAPs underlining the potential role of hemodynamics in their development., Abbreviations: cCAP, complicated carotid artery plaque; WSS, wall shear stress; OSI, oscillatory shear index., (© 2024 by American Journal of Neuroradiology.)

Background: ANCA (antineutrophil cytoplasmatic antibody)-associated vasculitis (AAV) mainly affects elderley people but adjusted therapy concepts for this patient group are lacking., Aim: The aim of this study was therefore to analyze differences in course and outcome of patients with AAV with respect to age., Materials and Methods: 62 patients were analyzed for treatment response, of whom 53 (85%) experienced adverse events (AE and SAE) that could be evaluated. Older (> 65 yrs.) versus younger (< 65 yrs.) patients were compared. Treatment response was assessed at 6 months, complications were assessed over 18 months., Results: Treatment response was not seen to differ by age groups. In multiple logistic regression, pulmonary involvement (OR = 6,9; CI = 1,7-27,8, p < 0,01) and ΔGFR [ml/min] (OR = 0,93; CI = 0,89-0,97, p < 0,01) were predictors of SAE. 14 patients had more than 1 SAE. Again, pulmonary involvement (28,2% vs. 78,6%, p < 0,01) was a risk factor and older patients (78,6% vs. 43,6%, p = 0,025) were more frequently affected. Patients with multiple SAEs received glucocorticoids of more than 5 mg/d for longer periods of time (171 ± 65 days vs. 120 ± 70 days, p = 0,03)., Discussion: No differences were found between older and younger patients with regard to treatment response. Multiple SAEs occurred more frequently in elderly patients. There was a correlation between pulmonary manifestation and duration of glucocorticoid therapy with a complicated course. The most frequent SAEs were infections requiring hospitalisation., Conclusion: Therapy for elderly patients should be individualized with the goal of a fast reduction of glucocorticoids. Special monitoring is indicated for elderly patients, especially those with pulmonary involvement., (© 2022. The Author(s).)

Physicians are expected to place the patient's interests above their own. Such prioritization has worldwide consent. It constitutes the difference between medicine and other professions. The present conceptual opinion paper summarizes the authors' clinical experience with patient care and student teaching during the last 45 years. The authors comment on their own conception by referring to present debates and prominent statements from the past. Fundamental changes in medicine have taken place over the last five decades. New diseases have emerged while diagnostic and therapeutic options for patients have grown steadily - along with healthcare costs. At the same time, economic and legal constraints for physicians have increased, as has moral pressure. The interaction of physicians with patients has gradually shifted from a personal to a factual relationship. In the factual, more formal relationship, the patient and physician represent equal partners of a legal contract, which jeopardizes the prioritization of the patient's interests. The formal relationship implies defensiveness. By contrast, in the personal relationship, the physician adopts an existentialist commitment while simultaneously enabling and respecting the patient's autonomous decision-making. The authors argue for the personal relationship. However, the patient and physician are no friends. Consequently, the physician in effect competes with the patient from a knowledge-based but opposite position. Both need to make efforts to consent and maintain the relationship even when they dissent. This implies that the physician does not simply comply with the patient's wishes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Keller, Ludwig and Huber-Lang.)

MRI is increasingly used as a diagnostic tool for visualising the dentoalveolar complex. A comprehensive review of the current indications and applications of MRI in the dental specialities of orthodontics (I), endodontics (II), prosthodontics (III), periodontics (IV), and oral surgery (V), pediatric dentistry (VI), operative dentistry is still missing and is therefore provided by the present work.The current literature on dental MRI shows that it is used for cephalometry in orthodontics and dentofacial orthopaedics, detection of dental pulp inflammation, characterisation of periapical and marginal periodontal pathologies of teeth, caries detection, and identification of the inferior alveolar nerve, impacted teeth and dentofacial anatomy for dental implant planning, respectively. Specific protocols regarding the miniature anatomy of the dentofacial complex, the presence of hard tissues, and foreign body restorations are used along with dedicated coils for the improved image quality of the facial skull.Dental MRI poses a clinically useful radiation-free imaging tool for visualising the dentoalveolar complex across dental specialities when respecting the indications and limitations.

Objectives: The aims of this study were to quantify T1/T2-relaxation times of the dental pulp, develop a realistic tooth model, and compare image quality between cone-beam computed tomography (CBCT) and high-resolution magnetic resonance imaging (MRI) of single teeth using a wireless inductively coupled intraoral coil., Methods: T1/T2-relaxometry was performed at 3 T in 10 healthy volunteers (283 teeth) to determine relaxation times of healthy dental pulp and develop a realistic tooth model using extracted human teeth. Eight MRI sequences (DESS, CISS, TrueFISP, FLASH, SPACE, TSE, MSVAT-SPACE, and UTE) were optimized for clinically applicable high-resolution imaging of the dental pulp. In model, image quality of all sequences was assessed quantitatively (contrast-to-noise ratio) and qualitatively (visibility of anatomical structures and extent of susceptibility artifacts using a 5-point scoring scale). Cone-beam computed tomography served as the reference modality for qualitative assessment. Statistical analysis was performed using 2-way analysis of variance, Fisher exact test, and Cohen κ., Results: In vivo, relaxometry of dental pulps revealed T1/T2 relaxation times at 3 T of 738 ± 100/171 ± 36 milliseconds. For all sequences, an isotropic resolution of (0.21 mm) 3 was achieved, with acquisition times ranging from 6:19 to 8:02 minutes. In model, the highest contrast-to-noise ratio values were observed for UTE, followed by TSE and CISS. The best image/artifact quality, however, was found for DESS (mean ± SD: 1.3 ± 0.3/2.2 ± 0.0), FLASH (1.5 ± 0.3/2.4 ± 0.1), and CISS (1.5 ± 0.4/2.5 ± 0.1), at a level comparable to CBCT (1.2 ± 0.3/2.1 ± 0.1)., Conclusions: Optimized MRI protocols using an intraoral coil at 3 T can achieve an image quality comparable to reference modality CBCT within clinically applicable acquisition times. Overall, DESS revealed the best results, followed by FLASH and CISS., Competing Interests: Conflicts of interest and sources of funding: none declared. Disclosure statement: This project was supported by the Dietmar Hopp Foundation (project no. 1DH2011152). The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: MRI is a frequently used tool in radiation therapy planning. For MR-based tumor segmentation, diffusion weighted imaging plays a major role, which can fail due to excessive image artifacts for head and neck cancer imaging. Here, an easy-to-use setup is presented for imaging of head and neck cancer patients in a radiotherapy thermoplastic fixation mask., Methods: In a prospective head and neck cancer study, MRI data of 29 patients has been acquired at 3 different time points during radiation treatment. The data was analyzed with respect to Nyquist ghosting artifacts in the diffusion images in conventional single shot and readout segmented EPI sequences. For 9 patients, an improved setup with water bags for B 0 homogenization was used, and the impact on artifact frequency was analyzed. Additionally, volunteer measurements with B 0 fieldmaps are presented., Results: The placement of water bags to the sides of the head during MRI measurements significantly reduces artefacts in diffusion MRI. The number of artifact-free images in readout segmented EPI increased from 74% to 95% of the cases. Volunteer measurements showed a significant increase in B 0 homogeneity across slices (head foot direction) as well as within each slice., Conclusions: The placement of water bags for B 0 homogenization is easy to implement, cost-efficient and does not impact patient comfort. Therefore, if very sophisticated soft- or hardware solutions are not present at a given site, or cannot be implemented due to restrictions from the thermoplastic mask, this is an excellent alternative to reduce artifacts in diffusion weighted imaging., (Copyright © 2022 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.)

Objectives: Accurate visualization of dental root canals is vital for the correct diagnosis and subsequent treatment. This work assesses the improvement of a dedicated new coil for dental magnetic resonance imaging (MRI) in comparison to conventional ones in terms of signal-to-noise ratio (SNR) and visibility., Materials and Methods: A newly developed intraoral flexible coil was used to display dental roots with MRI, and it provides improved sensitivity with a loop design and size adjusted to a single tooth anatomy. Ex vivo and in vivo measurements were performed on a 3 T clinical MR system, and results were compared with conventional head and surface coil images. Additional comparison was performed with a modified fast spin echo sequence and a constructive interference in steady-state sequence., Results: Ex vivo, an SNR gain of 6.3 could be achieved with the intraoral flexible coil setup, and higher visibility down to 200 μm was possible, whereas the external loop coil is limited to 400 μm. In vivo measurements in a volunteer resulted in an SNR gain of up to 4.5 with an improved delineation of the root canals, especially for the branch tissue splitting of the mesial root canal into mesial-buccal and mesial-lingual., Conclusions: In summary, we showed the feasibility of implementing a wireless coil approach with readily available dental practice materials for sealing and placement. Highly improved MRI scans can be acquired within clinically feasible scan times, and this might provide additional medical findings to supplement available x-ray images., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: Vessel wall enhancement (VWE) may be commonly seen on MRI images of asymptomatic subjects. This study aimed to characterize the VWE of the proximal internal carotid (ICA) and vertebral arteries (VA) in a non-vasculitic elderly patient cohort., Methods: Cranial MRI scans at 3 Tesla were performed in 43 patients (aged ≥ 50 years) with known malignancy for exclusion of cerebral metastases. For vessel wall imaging (VWI), a high-resolution compressed-sensing black-blood 3D T1-weighted fast (turbo) spin echo sequence (T1 CS-SPACE prototype) was applied post gadolinium with an isotropic resolution of 0.55 mm. Bilateral proximal intradural ICA and VA segments were evaluated for presence, morphology, and longitudinal extension of VWE., Results: Concentric VWE of the proximal intradural ICA was found in 13 (30%) patients, and of the proximal intradural VA in 39 (91%) patients. Mean longitudinal extension of VWE after dural entry was 13 mm in the VA and 2 mm in the ICA. In 14 of 39 patients (36%) with proximal intradural VWE, morphology of VWE was suggestive of the mere presence of vasa vasorum. In 25 patients (64 %), morphology indicated atherosclerotic lesions in addition to vasa vasorum., Conclusions: Vasa vasorum may account for concentric VWE within the proximal 2 mm of the ICA and 13 mm of the VA after dural entry in elderly subjects. Concentric VWE in these locations should not be confused with large artery vasculitis. Distal to these segments, VWE may be more likely related to pathologic conditions such as vasculitis., Key Points: • Vasa vasorum may account for concentric VWE within the proximal 2 mm of the ICA and 13 mm of the VA after dural entry in non-vasculitic elderly people. • Concentric enhancement within the proximal 2 mm of the intradural ICA and within the proximal 13 mm of the intradural VA portions should not be misinterpreted as vasculitis. • Distal of this, VWE is likely related to pathologic conditions, in case of concentric VWE suggestive of vasculitis., (© 2021. The Author(s).)

Objective: Assessment of vessel walls is an integral part in diagnosis and disease monitoring of vascular diseases such as vasculitis. Vessel wall imaging (VWI), in particular of intracranial arteries, is the domain of Magnetic Resonance Imaging (MRI) - but still remains a challenge. The tortuous anatomy of intracranial arteries and the need for high resolution within clinically acceptable scan times require special technical conditions regarding the hardware and software environments., Materials and Methods: In this work a dedicated framework for intracranial VWI is presented offering an optimized, black-blood 3D T1-weighted post-contrast Compressed Sensing (CS)-accelerated MRI sequence prototype combined with dedicated 3D-GUI supported post-processing tool for the CPR visualization of tortuous arbitrary vessel structures., Results: Using CS accelerated MRI sequence, the scanning time for high-resolution 3D black-blood CS-space data could be reduced to under 10 min. These data are adequate for a further processing to extract straightened visualizations (curved planar reformats - CPR). First patient data sets could be acquired in clinical environment., Conclusion: A highly versatile framework for VWI visualization was demonstrated utilizing a post-processing tool to extract CPR reformats from high-resolution 3D black-blood CS-SPACE data, enabling simplified and optimized assessment of intracranial arteries in intracranial vascular disorders, especially in suspected intracranial vasculitis, by stretching their tortuous course. The processing time from about 15-20 min per patient (data acquisition and further processing) allows the integration into clinical routine., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Introduction: Carotid geometry and wall shear stress (WSS) have been proposed as independent risk factors for the progression of carotid atherosclerosis, but this has not yet been demonstrated in larger longitudinal studies. Therefore, we investigated the impact of these biomarkers on carotid wall thickness in patients with high cardiovascular risk. Methods: Ninety-seven consecutive patients with hypertension, at least one additional cardiovascular risk factor and internal carotid artery (ICA) plaques (wall thickness ≥ 1.5 mm and degree of stenosis ≤ 50%) were prospectively included. They underwent high-resolution 3D multi-contrast and 4D flow MRI at 3 Tesla both at baseline and follow-up. Geometry (ICA/common carotid artery (CCA)-diameter ratio, bifurcation angle, tortuosity and wall thickness) and hemodynamics [WSS, oscillatory shear index (OSI)] of both carotid bifurcations were measured at baseline. Their predictive value for changes of wall thickness 12 months later was calculated using linear regression analysis for the entire study cohort (group 1, 97 patients) and after excluding patients with ICA stenosis ≥10% to rule out relevant inward remodeling (group 2, 61 patients). Results: In group 1, only tortuosity at baseline was independently associated with carotid wall thickness at follow-up (regression coefficient = -0.52, p < 0.001). However, after excluding patients with ICA stenosis ≥10% in group 2, both ICA/CCA-ratio (0.49, p < 0.001), bifurcation angle (0.04, p = 0.001), tortuosity (-0.30, p = 0.040), and WSS (-0.03, p = 0.010) at baseline were independently associated with changes of carotid wall thickness at follow-up. Conclusions: A large ICA bulb and bifurcation angle and low WSS seem to be independent risk factors for the progression of carotid atherosclerosis in the absence of ICA stenosis. By contrast, a high carotid tortuosity seems to be protective both in patients without and with ICA stenosis. These biomarkers may be helpful for the identification of patients who are at particular risk of wall thickness progression and who may benefit from intensified monitoring and treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Strecker, Krafft, Kaufhold, Hüllebrandt, Treppner, Ludwig, Köber, Hennemuth, Hennig and Harloff.)

Objective: To evaluate a novel liquid fiducial marker for intraoperative marking of the tumour resection surface in oral cancer patients to facilitate precise postoperative delineation of the interface between the tumour resection border and reconstructed tissue for intensity-modulated radiation therapy., Methods: A total of 200 markers were created by injecting the volumes of 10 µl, 20 µl, 30 µl, 40 µl and 50 µl of a liquid marker composed of sucrose acetoisobutyrate (SAIB) and iodinated sucrose acetoisobutyrate (x-SAIB) into the soft tissue of porcine mandible segments. Visibility of the resulting markers was quantified by threshold-based segmentation of the marker volume in CT- and CBCT imaging and by a comparison of signal intensities in MRI., Results: Even the lowest volume of SAIB-/x-SAIB investigated (10 µl) resulted in a higher visibility (CT Soft tissue : 88.18 ± 13.23 µl; CT Bone : 49.55 ± 7.62 µl; CBCT: 54.65 ± 12.58 µl) than observed with the incorporation of titanium ligature clips (CT Soft tissue : 50.15 ± 7.50 mm 3 ; CT Bone : 23.90 ± 3.39 mm 3 ; CBCT: 33.80 ± 9.20 mm 3 ). Markers created by the injection of 10 µl and 20 µl could reliably be delineated from markers created by the injection of higher volumes., Conclusion: SAIB/x-SAIB, which has recently become available as a Conformité Européenne (CE)-marked fiducial marker, provides an option for fast and reliable production of markers with excellent visibility in imaging modalities used in oral cancer radiation therapy (RT) planning routine.

Background and Purpose: In vasculopathies of the central nervous system, reliable and timely diagnosis is important against the background of significant morbidity and sequelae in cases of incorrect diagnosis or delayed treatment. Magnetic resonance imaging (MRI) plays a major role in the detection and monitoring of intracranial and extracranial vascular pathologies of different etiologies, in particular for evaluation of the vessel wall in addition to luminal information, thus allowing differentiation between various vasculopathies. Compressed-sensing black-blood MRI combines high image quality with relatively short acquisition time and offers promising potential in the context of neurovascular vessel wall imaging in clinical routine. This case review gives an overview of its application in the diagnosis of various intracranial and extracranial entities., Methods: An optimized high-resolution compressed-sensing black-blood 3D T1-weighted fast (turbo) spin echo technique (T1 CS-SPACE prototype) precontrast and postcontrast application at 3T was used for the evaluation of various vascular conditions in neuroradiology., Results: In this article seven cases of intracranial and extracranial arterial and venous vasculopathies with representative imaging findings in high-resolution compressed-sensing black-blood MRI are presented., Conclusion: High-resolution 3D T1 CS-SPACE black-blood MRI is capable of imaging various vascular entities in high detail with whole head coverage and low susceptibility for motion artifacts and within acceptable scan times. It represents a highly versatile, non-invasive technique for the visualization and differentiation of a wide variety of neurovascular arterial and venous disorders.

Objectives: Autologous bone grafts are the gold standard to augment deficient alveolar bone. Dimensional graft alterations during healing are not known as they are not accessible to radiography. Therefore, MRI was used to display autologous onlay bone grafts in vivo during early healing., Methods and Materials: Ten patients with alveolar bone atrophy and autologous onlay grafts were included. MRI was performed with a clinical MR system and an intraoral coil preoperatively (t0), 1 week (t1), 6 weeks (t2) and 12 weeks (t3) postoperatively, respectively. The graft volumes were assessed in MRI by manual segmentation by three examiners. Graft volumes for each time point were calculated and dimensional alteration was documented. Cortical and cancellous proportions of bone grafts were assessed. The intraobserver and interobserver variability were calculated. Statistical analysis was performed using a mixed linear regression model., Results: Autologous onlay bone grafts with cortical and cancellous properties were displayed in vivo in eight patients over 12 weeks. The fixation screws were visible as signal voids with a thin hyperintense fringe. The calculated volumes were between 0.12-0.74 cm 3 (t1), 0.15-0.73 cm 3 (t2), and 0.17-0.64 cm 3 (t3). Median changes of bone graft volumes of -15% were observed. There was no significant difference between the examiners ( p = 0.3)., Conclusions: MRI is eligible for the display and longitudinal observation of autologous onlay bone grafts. Image artifacts caused measurements deviations in some cases and minimized the precise assessment of graft volume. To the knowledge of the authors, this is the first study that used MRI for the longitudinal observation of autologous onlay bone grafts.

In Magnetic Resonance Imaging (MRI), radio frequency (RF) coils of different forms and shapes are used to maximize signal-to-noise ratio (SNR). RF coils are designed for clinical applications and have dimensions comparable with the target body part to be imaged, and they perform best when loaded by human tissue majority of which have conductivity values higher than 0.5 S/m. However, they are not properly tuned and matched for samples having low conductivity such as solid samples with low water content. Moreover, for samples with low filling factor and low conductivity, the noise in MRI is dominated by RF coil losses. In this case, RF coil design can be optimized to improve image SNR. Here, a new software tool (Multi-parameter Analytical Method for B1 and SNR Analysis) MAMBA is presented to design and compare volume coils of birdcage, solenoid, and loop-gap design for these samples. The input parameters of the tool are the sample properties, the coil design and the hardware properties, of which a relative SNR is determined. For that, a figure of merit is calculated from the coil sensitivity, applied resonant frequency and the resistive losses of sample, coil and capacitive components. The tool was tested in an ancient Egyptian mummy head which represents an extreme case of MRI with short T2*. Two optimized birdcage coils were designed using MAMBA, constructed and compared to a commercial transmit receive head coil. Calculated relative SNR values are in good agreement with the measurements., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: The posterior wall of the proximal internal carotid artery (ICA) is the predilection site for the development of stenosis. To optimally prevent stroke, identification of new risk factors for plaque progression is of high interest. Therefore, we studied the impact of carotid geometry and wall shear stress on cardiovascular magnetic resonance (CMR)-depicted wall thickness in the ICA of patients with high cardiovascular disease risk., Methods: One hundred twenty-one consecutive patients ≥50 years with hypertension, ≥1 additional cardiovascular risk factor and ICA plaque ≥1.5 mm thickness and < 50% stenosis were prospectively included. High-resolution 3D-multi-contrast (time of flight, T1, T2, proton density) and 4D flow CMR were performed for the assessment of morphological (bifurcation angle, ICA/common carotid artery (CCA) diameter ratio, tortuosity, and wall thickness) and hemodynamic parameters (absolute/systolic wall shear stress (WSS), oscillatory shear index (OSI)) in 242 carotid bifurcations., Results: We found lower absolute/systolic WSS, higher OSI and increased wall thickness in the posterior compared to the anterior wall of the ICA bulb (p < 0.001), whereas this correlation disappeared in ≥10% stenosis. Higher carotid tortuosity (regression coefficient = 0.764; p < 0.001) and lower ICA/CCA diameter ratio (regression coefficient = - 0.302; p < 0.001) were independent predictors of increased wall thickness even after adjustment for cardiovascular risk factors. This association was not found for bifurcation angle, WSS or OSI in multivariate regression analysis., Conclusions: High carotid tortuosity and low ICA diameter were independent predictors for wall thickness of the ICA bulb in this cross-sectional study, whereas this association was not present for WSS or OSI. Thus, consideration of geometric parameters of the carotid bifurcation could be helpful to identify patients at increased risk of carotid plaque generation. However, this association and the potential benefit of WSS measurement need to be further explored in a longitudinal study.

Objectives: The objective of this in vitro study was to assess the accuracy of fully guided implant placement following virtual implant planning based on MRI., Material and Methods: Sixteen human cadaver hemimandibles with single missing teeth (n = 3), partially edentulous (n = 6) and edentulous situations (n = 7) were imaged using MRI. MRI and optical scans obtained with an intraoral scanner, were imported into an implant planning software. Virtual prosthetic and implant planning were performed regarding hard- and soft-tissue anatomy. Drill guides were manufactured, and fully guided implant placement was performed. Buccal and lingual bone and implant nerve distance were measured by three examiners in preoperative MRI and postoperative CBCT. The implant position was assessed using a software for deviation of implant positions displayed in CBCT and optical scans, respectively., Results: MRI displayed relevant structures for implant planning such as cortical and cancellous bone, inferior alveolar nerve and neighboring teeth. Implant planning, CAD/CAM of drill guides and guided implant placement were performed. Deviations between planned and actual implant positions in postoperative CBCT and optical scans were 1.34 mm (SD 0.84 mm) and 1.03 mm (SD 0.46 mm) at implant shoulder; 1.41 mm (SD 0.88 mm) and 1.28 mm (SD 0.52 mm) at implant apex, and 4.84° (SD 3.18°) and 4.21° (SD 2.01°). Measurements in preoperative MRI and postoperative CBCT confirmed the compliance with minimum distances of implants to anatomical structures., Conclusions: Relevant anatomical structures for imaging diagnostics in implant dentistry are displayed with MRI. The accuracy of MRI-based fully guided implant placement in vitro is comparable to the workflow using CBCT., (© 2020 The Authors. Clinical Oral Implants Research published by John Wiley & Sons Ltd.)

Objectives: To present a workflow of virtual implant planning and guided implant surgery with magnetic resonance imaging (MRI) and virtual dental models without the use of ionizing radiation., Methods: Five patients scheduled for implant placement underwent an MR examination at three Tesla using individualized 2D and 3D turbo spin-echo (TSE) sequences and dedicated head coils. The MRI data and virtual dental models derived from either optical model scans or intraoral scans were imported to a virtual implant planning software (coDiagnostiX, Dental Wings, Montreal, Canada). Virtual prosthetic planning and implant planning were performed regarding the hard and soft tissue anatomy. A drill guide was designed on the virtual dental model using computer-aided design (CAD) and manufactured in-house, using a 3D printer (Eden 260V, Stratasys, Eden Prairie, MN, USA)., Results: The MRI displayed all relevant anatomical structures for dental implant planning such as cortical and cancellous bone, floor of the nasal and maxillary sinus, inferior alveolar nerve and neighboring teeth. The manual alignment of virtual dental models with the MRI was possible using anatomical landmarks. Dental implant planning, CAD/CAM of a drill guide and fully guided implant placement were successfully performed., Conclusions: Guided implant surgery is feasible with MRI without ionizing radiation. Further studies will have to be conducted to study the accuracy of the presented protocol and compare it to the current workflow of guided surgery using CBCT., (© 2020 The Authors. Clinical Oral Implants Research published by John Wiley & Sons Ltd.)