Visualization of intracranial aneurysms treated with Woven EndoBridge (WEB) devices using Ultrashort Echo Time Magnetic Resonance Imaging (UTE-MRI).

BACKGROUND AND PURPOSE: Assessing treatment success of intracranial aneurysms treated with Woven EndoBridge (WEB) devices using MRI is important in follow-up imaging. Depicting both the device configuration as well as reperfusion is challenging due to susceptibility artefacts. We evaluated the usefulness of contrast-enhanced 3D-Ultrashort Echo-Time (UTE) sequence in this setting. MATERIALS AND METHODS: In this prospective study, 12 patients (9 female) with 15 treated aneurysms were included. These 12 patients underwent 18 MRI examinations. Follow-up UTE-MRI controls were performed on the same 3-Tesla scanner. We compared the visualization of device configuration, artifact-related virtual stenosis of the parent vessel and WEB occlusion scale in 3D isotropic UTE-MRI post-contrast with standard time-of-flight (TOF) MR-angiography with (CE) and without intravenous contrast as well as DSA. Two interventional neuroradiologists rated the images separately and in consensus. RESULTS: Visualization of the WEB device position and configuration was rated superior or highly superior using the UTE sequence in 17/18 MRIs compared to TOF-MRA. Artifact-related virtual stenosis of the parent vessel was significantly lower in UTE-MRI compared to TOF and CE-TOF. Reperfusion was visible in 8/18 controls in DSA. TOF was able to grade reperfusion correctly in 16 cases, CE-TOF in 16 cases and UTE in 17 cases. CONCLUSIONS: Contrast-enhanced UTE is a novel MRI sequence that shows benefit compared to standard sequences in non-invasive and radiation-free follow-up imaging of intracranial aneurysms treated using the WEB-device. ABBREVIATIONS: ACoA = anterior communicating artery, BA = basilar artery, CEA = contrast enhanced angiography, ICA = internal carotid artery, MCA = middle cerebral artery, PCom = posterior communicating artery TOF-CE = contrast enhanced time-of-flight angiography, UTE = ultra-short echo time, WEB = woven endobridge.

Therapeutic options to manage bleeding in a dentist's office / Therapieoptionen bei Blutungen in der zahnärztlichen Praxis

This manuscript provides an overview of therapeutic options for the problem of bleeding in a dentist's office. Bleeding after tooth extraction is a very common finding in dental medicine and persistent blood in the mouth is obviously uncomfortable and sometimes terrifying for the patient. Most bleedings can be stopped simply with compression, in some cases a homeostatic therapy is necessary. For local compression, a swab with tranexamic acid is useful. If local compression is not sufficient, sutures are often an option. A very effective therapy would also be Tabotamp®, a local hemostypticum which is placed onto the bleeding and should increase the thrombocytic aggregation. In the worst case Floseal®, a human Thrombin, can be placed locally. It stops the bleeding very fast and sufficiently.

Simultaneous Multislice Diffusion-Weighted Imaging of the Kidney: A Systematic Analysis of Image Quality.

OBJECTIVES: The aims of this study were to implement a protocol for simultaneous multislice (SMS) accelerated diffusion-weighted imaging (DWI) of the kidneys and to perform a systematic analysis of image quality of the data sets. MATERIALS AND METHODS: Ten healthy subjects and 5 patients with renal masses underwent DWI of the kidney in this prospective institutional review board-approved study on a 3 T magnetic resonance scanner. Simultaneous multislice DWI echo-planar sequences (acceleration factors [AFs] 2 and 3) were compared with conventional echo-planar DWI as reference standard for each acquisition scheme. The following 3 acquisition schemes were applied: comparison A, with increased number of acquisitions at constant scan time; comparison B, with reduction of acquisition time; and comparison C, with increased slice resolution (constant acquisition time, increasing number of slices). Interreader reliability was analyzed by calculating the intraclass correlation coefficient (ICC). Qualitative image quality features were evaluated by 2 independent radiologists on a 5-point Likert scale. Quantification accuracy of the apparent diffusion coefficients (ADCs) and signal-to-noise ratios (SNRs) were assessed by region of interest analysis. Furthermore, lesion conspicuity in the 5 patients was assessed using a 5-point Likert scale by 2 independent radiologists. RESULTS: Interreader agreement was substantial with an ICC of 0.68 for the overall image quality and an ICC of 0.73 for the analysis of artifacts. In comparison A, AF2 resulted in increased SNR (P < 0.05) by 21% at stable image quality scores (image quality: P = 0.76, artifacts: P = 0.21). In comparison B, applying AF2, the scan time could be reduced by 46% without significant reduction in qualitative image quality scores (P = 0.059) or SNR (P = 0.126). In comparison C, slice resolution could be improved by 28% using AF2 with stable image quality scores and SNR. In general, AF3 resulted in reduced image quality and SNR. Significantly reduced ADC values were observed for AF3 in comparison C (cortex: P = 0.003; medulla: P = 0.001) compared with the standard echo-planar imaging sequence. The conventional DWI and the SMS DWI with AF2 showed stable lesion conspicuity ([AF1/AF2]: reader 1 [1.8/1.4] and reader 2 [1.8/1.4]). The lesion conspicuity was lower using AF3 (reader 1: 2.2 and reader 2: 1.8). CONCLUSIONS: In conclusion, SMS DWI of the kidney is a potential tool to substantially reduce scan time without negative effects on SNR, ADC quantification accuracy, and image quality if an AF2 is used. Although AF3 results in even higher scan time reduction, a negative impact on image quality, SNR, ADC quantification accuracy, and lesion conspicuity must be considered.

Evaluation of a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography of scaphoid fixation screws.

OBJECTIVES: The aim of this study was to evaluate a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography (FDCT) of scaphoid fixation screws. FDCT has gained interest in imaging small anatomic structures of the appendicular skeleton. Angiographic C-arm systems with flat detectors allow fluoroscopy and FDCT imaging in a one-stop procedure emphasizing their role as an ideal intraoperative imaging tool. However, FDCT imaging can be significantly impaired by artefacts induced by fixation screws. MATERIALS AND METHODS: Following ethical board approval, commercially available scaphoid fixation screws were inserted into six cadaveric specimens in order to fix artificially induced scaphoid fractures. FDCT images corrected with the algorithm were compared to uncorrected images both quantitatively and qualitatively by two independent radiologists in terms of artefacts, screw contour, fracture line visibility, bone visibility, and soft tissue definition. Normal distribution of variables was evaluated using the Kolmogorov-Smirnov test. In case of normal distribution, quantitative variables were compared using paired Student's t tests. The Wilcoxon signed-rank test was used for quantitative variables without normal distribution and all qualitative variables. A p value of < 0.05 was considered to indicate statistically significant differences. RESULTS: Metal artefacts were significantly reduced by the correction algorithm (p < 0.001), and the fracture line was more clearly defined (p < 0.01). The inter-observer reliability was "almost perfect" (intra-class correlation coefficient 0.85, p < 0.001). CONCLUSIONS: The prototype correction algorithm in FDCT for metal artefacts induced by scaphoid fixation screws may facilitate intra- and postoperative follow-up imaging. KEY POINTS: Flat detector computed tomography (FDCT) is a helpful imaging tool for scaphoid fixation. The correction algorithm significantly reduces artefacts in FDCT induced by scaphoid fixation screws. This may facilitate intra- and postoperative follow-up imaging.