From Perviousness to Plaque Imaging in Acute Basilar Occlusions: The Impact of Underlying Stenosis and How to Detect It.

Background and Purpose- Recent studies show that mechanical thrombectomy of acute basilar artery occlusions (BAO) results in high rates of successful recanalization and good outcomes, but predictors are not completely established yet. Varying occlusion types may benefit differently, and especially, an underlying basilar stenosis (BS) seems to have an impact. Aim of this study was to investigate angiographic and clinical differences in BAO subtypes and to test the potential of perviousness measures for a preinterventional identification of clinically relevant different occlusion types. Methods- All consecutive patients with acute BAO, endovascular treated at a single comprehensive stroke center, were included. Different occlusion patterns, especially underlying BS, were identified and analyzed in respect of angiographic and clinical (National Institutes of Health Stroke Scale/modified Rankin Scale) outcome parameters (N=115). Thrombus perviousness measures (change in thrombus attenuation Δt and corrected void fraction ε) were assessed in admission computed tomography imaging and correlated to different etiological subgroups. Results- Despite comparable rates of successful recanalization (87% for BAO with BS versus 95% without BS), the BS group showed worse clinical outcome with higher National Institutes of Health Stroke Scale/modified Rankin Scale values (P=0.002/0.003). The group of BS turned out to have lower thrombus density values in unenhanced scans (mean, 42.0 Hounsfield units) and higher perviousness measures Δt (mean, 34.6 Hounsfield units) and ε (mean, 0.23) than thrombi without an underlying BS (mean, 53.6 Hounsfield units/13.1 Hounsfield units/0.08, P=0.01/ 0.004/ 0.001). Conclusions- In agreement with previous studies, outcome of mechanical thrombectomy of BAO seems to depend on pathogenesis with less clinical benefit for underlying BS, raising the question of early identification of this subgroup. Perviousness showed a high potential to differentiate acute BAO with and without BS, possibly usable as an admission imaging marker for BS.

[Update polytrauma and computed tomography in ongoing resuscitation : ABCDE and "diagnose first what kills first"]. / Update Polytrauma und Computertomographie unter Reanimationsbedingungen : ABCDE und "diagnose first what kills first".

CLINICAL ISSUE: The mean number of trauma room admissions and applied CT dose increase as the severity of injuries decreases. Therefore, appropriateness of established procedures should be re-evaluated. STANDARD RADIOLOGICAL METHODS: Considering severely injured patients with an Injury Severity Score (ISS) ≥16, whole body CT (WB-CT) compared to selective CT decreased mortality by about 25%. Thus, the ISS is a good indicator for the severity of injuries. However, since ISS can only be determined after diagnosis, it does not help with the primary assessment. METHODOLOGICAL INNOVATION AND EVALUATION: In addition to the currently used very fast WB-CT protocol with the highest diagnostic precision, a second protocol should be established applying a substantially lower dose. Under ongoing resuscitation, WB-CT often makes a substantial contribution towards targeted therapy or to justifying the discontinuation of resuscitation measures. The WB-CT findings should be performed several times and, at least in the acute emergency situation, it should follow the ABCDE scheme as close as possible. PRACTICAL RECOMMENDATIONS: In the trauma room it should be initially decided whether the classification as polytrauma is to be maintained. If yes, every institution should provide a dose-reduced WB-CT protocol in addition to the maximum variant used so far. Dose-reduced WB-CT seems to be appropriate for stable and oriented patients, who receive a CT primarily because of the trauma mechanism. Even under resuscitation conditions, WB-CT is easy to perform and medically as well as ethically of high value. The reporting and communication should be structured according to "diagnose first what kills first".

Analysis of the three-dimensional anatomical variance of the distal radius using 3D shape models.

BACKGROUND: Various medical fields rely on detailed anatomical knowledge of the distal radius. Current studies are limited to two-dimensional analysis and biased by varying measurement locations. The aims were to 1) generate 3D shape models of the distal radius and investigate variations in the 3D shape, 2) generate and assess morphometrics in standardized cut planes, and 3) test the model's classification accuracy. METHODS: The local radiographic database was screened for CT-scans of intact radii. 1) The data sets were segmented and 3D surface models generated. Statistical 3D shape models were computed (overall, gender and side separate) and the 3D shape variation assessed by evaluating the number of modes. 2) Anatomical landmarks were assigned and used to define three standardized cross-sectional cut planes perpendicular to the main axis. Cut planes were generated for the mean shape models and each individual radius. For each cut plane, the following morphometric parameters were calculated and compared: maximum width and depth, perimeter and area. 3) The overall shape model was utilized to evaluate the predictive value (leave one out cross validation) for gender and side identification within the study population. RESULTS: Eighty-six radii (45 left, 44% female, 40 ± 18 years) were included. 1) Overall, side and gender specific statistical 3D models were successfully generated. The first mode explained 37% of the overall variance. Left radii had a higher shape variance (number of modes: 20 female / 23 male) compared to right radii (number of modes: 6 female / 6 male). 2) Standardized cut planes could be defined using anatomical landmarks. All morphometric parameters decreased from distal to proximal. Male radii were larger than female radii with no significant side difference. 3) The overall shape model had a combined median classification probability for side and gender of 80%. CONCLUSIONS: Statistical 3D shape models of the distal radius can be generated using clinical CT-data sets. These models can be used to assess overall bone variance, define and analyze standardized cut-planes, and identify the gender of an unknown sample. These data highlight the potential of shape models to assess the 3D anatomy and anatomical variance of human bones.

Is It Possible to Replace Conventional Radiography (CR) with a Dose Neutral Computed Tomography (CT) of the Cervical Spine in Emergency Radiology-An Experimental Cadaver Study.

The purpose of this experimental study on recently deceased human cadavers was to investigate whether (I) the radiation exposure of the cervical spine CT can be reduced comparable to a dose level of conventional radiography (CR); and (II) whether and which human body parameters can be predictive for higher dose reduction potential (in this context). MATERIALS AND METHODS: Seventy serial CT scans of the cervical spine of 10 human cadavers undergoing postmortem virtual autopsy were taken using stepwise decreasing upper limits of the tube current (300 mAs, 150 mAs, 110 mAs, 80 mAs, 60 mAs, 40 mAs, and 20 mAs) at 120 kVp. An additional scan acquired at a fixed tube current of 300 mAs served as a reference. Images were reconstructed with filtered back projection and the upper (C1-4) and lower (C4-7) cervical spine were evaluated by three blinded readers for image quality, regarding diagnostic value and resolution of anatomical structures according to a semiquantitative three-point-scale. Dose values and individual physical parameters were recorded. The relationship of diagnostic IQ, dose reduction level, and patients' physical parameters were investigated. The high-contrast resolution of the applied CT protocols was tested in an additional phantom study. RESULTS: The IQ of the upper cervical spine was diagnostic at 1.69 ± 0.58 mGy (CTDI) corresponding to 0.20 ± 0.07 mSv (effective dose) in all cadavers. IQ of the lower cervical spine was diagnostic at 4.77 ± 1.86 mGy corresponding to 0.560 ± 0.21 mSv (effective dose) in seven cadavers and at 2.60 ± 0.93 mGy corresponding to 0.31 ± 0.11 mSv in four cadavers. Significant correlation was detected for BMI (0.8366; p = 0.002548) and the anteroposterior (a.p.) chest diameter (0.8363; p = 0.002566), shoulder positioning (0.79799; p = 0.00995), and radiation exposure. CONCLUSIONS: Conventional radiography can be replaced with a nearly dose-neutral CT scan of the cervical spine.

Introduction of CTA-index as Simplified Measuring Method for Thrombus Perviousness.

PURPOSE: Thrombus features on admission CT are useful imaging markers for clot characterization, stroke pathogenesis and outcome prediction. In this context, thrombus perviousness is a promising parameter, but reliable assessment in daily clinical practice is demanding. The aim of the present study was to evaluate an easy to assess measuring method for thrombus permeability at the time of admission. METHODS: The CTA-index, which measures relative thrombus attenuation on admission CTA, was compared to the known perviousness parameter in a cohort of 101 patients with large-vessel occlusions of the middle cerebral artery and correlated to clinical outcome parameters (mRS after 90 days, ≤2 rated as favorable). For validation, this correlation was tested in a second independent cohort (n = 87), and possible associations between the CTA-index and outcome measurements (NIHSS/mRS/mTICI) were assessed. RESULTS: In the first cohort a coherence between conventional perviousness measurements and the CTA-index was shown. The CTA-index differed significantly between favorable (-0.55 ± 0.16) and non-favorable outcomes (-0.64 ± 0.14, p = 0.01). In the validation cohort this result could be independently reproduced (-0.52 ± 0.13/-0.70 ± 0.09, p < 0.01). The CTA-index showed an association with low NIHSS at discharge (p < 0.01), favorable outcome after 90 days (p < 0.001) and with better reperfusion (measured by mTICI score, p = 0.04). CONCLUSION: The CTA-index is an easy to assess imaging parameter on admission CTA in the acute stroke phase and is associated with angiographic and clinical outcome. It can be considered as a simplified measuring method for thrombus perviousness, which is known to provide useful information for further stroke progress and clinical course as well as therapeutic and rehabilitative decisions.

European Society of Emergency Radiology: guideline on radiological polytrauma imaging and service (short version).

BACKGROUND: Although some national recommendations for the role of radiology in a polytrauma service exist, there are no European guidelines to date. Additionally, for many interdisciplinary guidelines, radiology tends to be under-represented. These factors motivated the European Society of Emergency Radiology (ESER) to develop radiologically-centred polytrauma guidelines. RESULTS: Evidence-based decisions were made on 68 individual aspects of polytrauma imaging at two ESER consensus conferences. For severely injured patients, whole-body CT (WBCT) has been shown to significantly reduce mortality when compared to targeted, selective CT. However, this advantage must be balanced against the radiation risk of performing more WBCTs, especially in less severely injured patients. For this reason, we recommend a second lower dose WBCT protocol as an alternative in certain clinical scenarios. The ESER Guideline on Radiological Polytrauma Imaging and Service is published in two versions: a full version (download from the ESER homepage, https://www.eser-society.org ) and a short version also covering all recommendations (this article). CONCLUSIONS: Once a patient has been accurately classified as polytrauma, each institution should be able to choose from at least two WBCT protocols. One protocol should be optimised regarding time and precision, and is already used by most institutions (variant A). The second protocol should be dose reduced and used for clinically stable and oriented patients who nonetheless require a CT because the history suggests possible serious injury (variant B). Reading, interpretation and communication of the report should be structured clinically following the ABCDE format, i.e. diagnose first what kills first.

Intraosseous needles in pediatric cadavers: Rate of malposition.

AIM OF THE STUDY: Intraosseous vascular access is a commonly conducted procedure especially in pediatric resuscitation. Very high success rates for intraosseous (IO) devices are reported. Aim of the study was to describe the rates of malposition of intraosseous needles (ION) in pediatric cadavers via post-mortem computed tomography (PMCT). METHODS: 212 consecutive pediatric cadavers underwent PMCT, of which 38 cadavers had visible ION and were included in the study. They were divided into two subgroups depending on their age (n = 22 infant cadavers (age <1 year) and n = 16 child cadavers (age ≥1 year)). Two independent readers evaluated the number and position of ION. RESULTS: In 22 infant cadavers 34 ION were found. Malposition of at least one ION was visible in 14 subjects (64%), among which 7 cadavers (32%) even had no correctly placed ION, thus being without established vascular access. Overall, 16 of the 34 used ION devices (47%) were in malposition. 23 ION were found in 16 child cadavers. In 8 subjects (50%) at least one ION was malpositioned, among which 3 cadavers (19%) had no correctly placed ION, resulting in a complete absence of vascular access. Overall, 9 of the 23 ION devices (39%) were malpositioned. CONCLUSION: Our study showed relatively high malposition rates for ION devices in pediatric cadavers which was not to be assumed regarding the success rates of 80% and higher in previous literature. This should be clarified by further studies in living patients.

DDX6 transfers P-TEFb kinase to the AF4/AF4N (AFF1) super elongation complex.

AF4/AFF1 and AF5/AFF4 are both backbones for the assembly of "super elongation complexes" (SECs) that exert 2 distinct functions after the recruitment of P-TEFb from the 7SK snRNP: (1) initiation and elongation of RNA polymerase II gene transcription, and (2) modification of transcribed gene regions by distinct histone methylation patterns. In this study we aimed to investigate one of the initial steps, namely how P-TEFb is transferred from 7SK snRNPs to the SECs. In particular, we were interested in the role of DDX6 that we have recently identified as part of the AF4 complex. DDX6 is an evolutionarily conserved member of the DEAD-box RNA helicase family that is known to control miRNA and mRNA biology (translation, storage and degradation). Overexpressed DDX6 is associated with different cancer types and with c-Myc protein overexpression. We could demonstrate that DDX6 binds to 7SK snRNA and causes the release and transfer of P-TEFb to the AF4/AF4N SEC. DDX6 also binds stably to AF4 and AF4N as demonstrated by GST pull-down and co-immunoprecipitation experiments. As a consequence, overexpression of either AF4/AF4N or DDX6 resulted in a strong increase of mRNA production (5-6 fold), while their simultaneous expression increased the cellular mRNA production by 11-fold. Conversely, the corresponding knockdown of DDX6 decreased mRNA production by 70%. In conclusion, AF4/AF4N and DDX6 represent key molecules for the elongation process of gene transcription and a model will be proposed for the hand-over process of P-TEFb to SECs.