T2 prolongation in the cerebellar vermis on prenatal MRI of fetuses with Chiari 2 malformations.

AIM: To describe a new finding in fetuses with Chiari 2 malformations recognised at in utero (iu) magnetic resonance imaging (MRI), specifically T2 prolongation (high signal) in the cerebellar vermis. MATERIALS AND METHODS: This was a prospective observational study of iuMRI studies performed at two time points on 20 fetuses with Chiari 2 malformations and 10 control fetuses at the same time points. High T2 signal in the cerebellar vermis was noted and correlated with posterior fossa dimensions was assessed. RESULTS: High T2 signal in the cerebellar vermis was found in over half of the fetuses with a Chiari 2 malformation, but was not correlated with the degree of reduction in size of the bony posterior fossa. CONCLUSION: The present findings suggest that abnormal high T2 signal in the cerebellum is common in fetuses with Chiari 2 malformations and although the cause of the signal change is not known at present it may represent vasogenic oedema as a result of restricted venous drainage.

Effect of Collaterals on Clinical Presentation, Baseline Imaging, Complications, and Outcome in Acute Stroke.

BACKGROUND AND PURPOSE: Good CTA collaterals independently predict good outcome in acute ischemic stroke. Our aim was to evaluate the role of collateral circulation and its added benefit over CTP-derived total ischemic volume as a predictor of baseline NIHSS score, total ischemic volume, hemorrhagic transformation, final infarct size, and a modified Rankin Scale score >2. MATERIALS AND METHODS: This was a retrospective study of 395 patients with stroke dichotomized by recanalization (recanalization positive/recanalization negative) and collateral status. Clot burden score was quantified on baseline CTA. Total ischemic volumes were derived from thresholded CTP maps. Final infarct size was assessed on follow-up CT/MRI. We performed uni-/multivariate analyses for each outcome, adjusting for rtPA status, using general linear (continuous variables) and logistic (binary variables) regression. Model comparison with collateral score and total ischemic volume was performed using the F or likelihood ratio test. RESULTS: Collateral presence independently and inversely predicted all outcomes except hemorrhagic transformation in patients who were recanalization negative and mRS >2 in patients who were recanalization positive. The greatest collateral benefit occurred in patients who were recanalization negative, contributing 16.5% and 19.2% of the variability for final infarct size and mRS >2. The collateral score model is superior to the total ischemic volume for mRS >2 prediction, but a combination of total ischemic volume and collateral score is superior for mRS >2 and final infarct prediction (24% and 28% variability, respectively). In patients who were recanalization positive, a model including collateral score and total ischemic volume was superior to that of total ischemic volume for hemorrhagic transformation and final infarct prediction but was muted compared with patients who were recanalization negative (11.3% and 16.9% variability). CONCLUSIONS: Collateral circulation is an independent predictor of all outcomes, but the magnitude of significance varies, greater in patients who were recanalization negative versus recanalization positive. Total ischemic volume assessment is complementary to collateral score in many cases.

A comparison of free-hand vs laser-guided long-axis ultrasound techniques in novice users.

OBJECTIVE: The increasing use of point-of-care ultrasonography for targeted procedures justifies a device that helps both novices in training and experts perform the long-axis needle approach. The initial success of traditional needle guidance devices in reducing the time of target procedures is not universal and they can be cumbersome. We aim to investigate whether the less bulky and previously untested laser guide can succeed in reducing procedure time in novice ultrasonographers. METHODS: 82 medical students with no ultrasound experience volunteered. Random allocation determined whether, during a targeted procedure in a turkey breast and olive phantom, participants were assisted by the laser guide or not. The time taken to pierce the target was recorded at 1-cm depth. RESULTS: The mean procedure time in the laser-assisted (LA) group was 25.1 s (14.0 s; 18.0-25.0 s). The mean procedure time in the free-hand group was 45.5 s (23.0 s; 7.0-55.0 s). The procedure time in the LA group was significantly reduced (p<0.01). CONCLUSION: The laser guide significantly improved procedure times. It is felt that the cheaper, smaller, easy to integrate, sterile and more user-friendly laser guidance unit may be a better alternative to the needle guide in improving procedure times for the novice ultrasonographer or to assist the expert, during training for, or performance of, ultrasound-guided targeted procedures. ADVANCES IN KNOWLEDGE: Following from the prototype paper, this is the first study to investigate the effectiveness of attaching a laser-guidance device to an ultrasound probe. The device succeeded in reducing the procedure times of targeted procedures.

The use of in utero MRI to supplement ultrasound in the foetus at high risk of developmental brain or spine abnormality.

OBJECTIVES: It is widely accepted that the diagnosis of foetal central nervous system (CNS) abnormalities can be improved by performing MRI examinations in utero. Most of the published literature has concentrated on pregnancies in which a developmental abnormality has been detected (or suspected) on ultrasound in an otherwise low-risk pregnancy. In this paper, we test the hypothesis that in utero MRI of the foetal brain in high-risk pregnancies will detect abnormalities not shown by ultrasound at a rate that justifies its use in clinical practice. METHODS: 100 females were recruited into the study from foeto-maternal or clinical genetic departments. They all had a foetus/child with a CNS malformation from an earlier pregnancy, which led to an increased risk of recurrence being quoted for the present pregnancy. All in utero MRI examinations were performed on 1.5 T clinical MRI systems at 18 weeks gestational age or later. RESULTS: In 78% of cases, the ultrasound and MRI results agreed and showed no abnormality. In 13%, ultrasound and MRI described identical abnormal findings. In 9%, the ultrasound and MRI examinations had discrepant findings; in all these cases the MRI findings described more serious CNS pathology. The effects on management were judged to be major, by at least one assessor, in 7/9 of those cases. CONCLUSION: As in many other situations involving antenatal detection of CNS abnormalities, in utero MRI should be considered in females with increased risk of foetal CNS malformation based on the results of an earlier pregnancy. Advances in knowledge In utero MRI of the foetus has an important role in antenatal diagnosis of females carrying a foetus with an increased risk of a brain abnormality.