Perfusion MRI as a neurosurgical tool for improved targeting in stereotactic tumor biopsies.

OBJECTIVE: Stereotactic biopsies are subject to sampling errors (essentially due to target selection). The presence of contrast enhancement is not a reliable marker of malignancy. The goal of the present study was to determine whether perfusion-weighted imaging can improve target selection in stereotactic biopsies. METHODS: We studied 21 consecutive stereotactic biopsies between June 2009 and March 2010. Perfusion-weighted magnetic resonance imaging (MRI) was integrated into our neuronavigator. Perfusion-weighted imaging was used as an adjunct to conventional MRI data for target determination. Conventional MRI alone was used to determine the trajectory. RESULTS: We found a linear correlation between regional cerebral blood volume (rCBV) and vessel density (number of vessels per mm(2); R = 0.64; p < 0.001). Perfusion-weighted imaging facilitated target determination in 11 cases (52.4%), all of which were histopathologically diagnosed as glial tumors. For glial tumors, which presented with contrast enhancement, perfusion-weighted imaging identified a more precisely delimited target in 9 cases, a different target in 1 case, and exactly the same target in 1 other case. In all cases, perfusion-selected sampling provided information on cellular features and tumor grading. rCBV was significantly associated with grading (p < 0.01), endothelial proliferation (p < 0.01), and vessel density (p < 0.01). For lesions with rCBV values ≤1, perfusion-weighted MRI did not help to determine the target but was useful for surgical management. CONCLUSIONS: For stereotactic biopsies, targeting based on perfusion-weighted imaging is a feasible method for reducing the sampling error and improving target selection in the histopathological diagnosis of tumors with high rCBVs.

A comparative study of perfusion measurement in brain tumours at 3 Tesla MR: Arterial spin labeling versus dynamic susceptibility contrast-enhanced MRI.

PURPOSE: To prove the feasibility of arterial spin labeling (ASL) to explore brain tumors by comparing dynamic susceptibility contrast-enhanced MRI to ASL at 3T MR. MATERIALS AND METHODS: Twenty-seven patients were included presenting 9 gliomas, 10 metastases and 8 meningiomas. All were explored by a pseudo-continuous ASL and dynamic susceptibility contrast-enhanced T2* perfusion sequence. Two neuroradiologists analyzed the cerebral blood flow (CBF) maps to assess feasibility, examination quality and quantitative comparison. The Spearman nonparametric correlation test and the Bland-Altman graphic test were used to analyze our quantitative results. RESULTS: 92% of ASL CBF maps were informative. ASL detected all lesions as well as dynamic susceptibility contrast-enhanced MRI. Both sequences provide relative quantitative CBF values closely correlated. CONCLUSION: On a 3T MR unit, ASL is a good alternative to dynamic susceptibility contrast-enhanced MRI when contrast medium is contraindicated or intravenous injection is not possible. Its results on relative CBF parameters are similar to contrast-injected perfusion.

[Vertebroplasty: 10 years clinical and radiological follow-up]. / Vertébroplastie: évaluation clinique et radiologique à plus de dix ans.

OBJECTIVES: Ten years follow-up of the first patients treated with percutaneous vertebroplasty. PATIENT AND METHODS: Eighteen patients were retrospectively reviewed having undergone vertebroplasty in our centre between 1989 and 1998. Eight were treated for angioma, eight for osteoporotic compression and two followed for myeloma. They all underwent clinical and radiological evaluation in 2007 (standard X-rays, CT scan and MRI). These examinations were compared to prior baseline pre- and post-therapeutic images. RESULTS: Radiological characteristic of cement remained unchanged in the long term and there was no modification of anatomical structures in contact with it. Even if the distribution of cement was asymmetrical there was no fracture of the treated vertebras at distance. Degenerative changes of discs facing the vertebroplasty were not more pronounced than for distant discs. We found no significant signal or density anomaly of disc in contact direct with cement. 38.8 % of the patients presented new fractures (n=30). Seventy percent of the fractures were multiple and contiguous. In the long term, all patients reported improvement of pain after the procedure. CONCLUSION: In our series, we found a good stability of treatment over time. This study shows the long-term safety of percutaneous acrylic vertebroplasty, in particular harmlessness of cement for bone and discs in contact.

[Arterial spin labeling: state of the art]. / Etat de l'art sur le Marquage de Spin Artériel ou ASL.

UNLABELLED: Arterial spin labeling (ASL) perfusion MR imaging is a technique by which water from circulating arterial blood is magnetically labeled and acts as a diffusible tracer allowing non-invasive measurement of cerebral blood flow. In this paper, the technique and current applications in neuroimaging will be reviewed. CURRENT STATUS: First, the technical principles of ASL will be reviewed and both available techniques (continuous and pulsed ASL) explained. A review of the literature will demonstrate advances with the techniques of ASL and its clinical impact. Clinical research involves normal volunteers and patients with ischemic and tumoral pathologies. CONCLUSION: Recent technical advances have improved the sensitivity of ASL perfusion MR imaging. The routine clinical use of ASL at 3.0 Tesla should increase over the next few years.

[Bithalamic infarct: is there an evocative aspect? Radioclinical study]. / Accident vasculaire ischémique bithalamique: existe-t-il un tableau évocateur ? Etude radioclinique.

INTRODUCTION: Bithalamic paramedian infarcts are uncommon. This stroke results in a complex clinical syndrome. CASE REPORT: We report four cases of bithalamic paramedian infarcts with a presumed mechanism of occlusion of a single thalamic paramedian artery. DISCUSSION: This normal anatomic variant corresponds to an asymmetrical common trunk for the two thalamosubthalamic paramedian arteries arising from a P1 segment (type IIb in the G. Percheron classification dating from 1977). A literature analysis (from 1985 to 2006) allowed us to identify the most widely reported clinical signs. Four main clinical findings are described: vertical gaze palsy (65%), memory impairment (58%), confusion (53%) and coma (42%). We also found these symptoms in our patients but rarely associated; however, all four patients had exhibited episodes of drowsiness. In this article, we discuss the anatomy-function correlation responsible for such clinical variability. CONCLUSION: Clinicians should be aware of this diagnosis to better understand the imaging results which provide confirmation. Although the literature describes frequently severe consciousness disorders such as coma, this diagnosis must also be considered in patients presenting a simple fluctuation of consciousness, e.g. hypersomnia.

Dynamic contrast-enhanced T2*-weighted MR imaging: a peritumoral brain oedema study.

BACKGROUND AND PURPOSE: Glioma and meningioma are the two most common types of primary brain tumor. The aim of the present study was to analyze, using dynamic susceptibility contrast MR perfusion imaging, the effect of angiogenesis on peritumoral tissue. METHODS: In this prospective study, conducted from December 2003 to March 2005, out of 18 patients recruited, 12 were included (six with meningioma, six with glioblastoma). Using rates of maximum signal drop (MSD), we drew regions of interest (ROI) starting near the lesion, and gradually moving outwards to areas of distant edema in axial and sagittal planes at 10, 20 and 30 mm from the tumor. We also drew ROI on the contralateral brain white matter to obtain a normal baseline for comparison (relative MSD; rMSD). RESULTS: In regions of peritumoral T2 hypersignals, we observed a decrease in rMSD with distance from glioblastoma due to reduced angiogenesis, and an increase in rMSD with distance from meningioma, probably due to a reduced mass effect. CONCLUSION: In our study, dynamic susceptibility contrast MR perfusion imaging, using MSD as a parameter, revealed differences between meningioma and glioblastoma peritumoral tissue due to changes in angiogenesis.

Non-recurrent laryngeal nerve related to thyroid surgery: report of three cases.

PURPOSE OF THE STUDY: We aimed to highlight a rare anatomical variation involving the recurrent laryngeal nerve, and to emphasise its implications for thyroid surgery. MATERIALS AND METHODS: Over a period of 13 years, 993 patients underwent thyroid surgery; 1557 recurrent laryngeal nerves (887 on the right side) were exposed. RESULTS: Three non-recurrent laryngeal nerves were found on the right side, associated with a retro-oesophageal subclavian artery. One case was suspected before surgery. DISCUSSION: Several variations in the path and branches of the recurrent laryngeal nerve have been reported in the literature. The frequency of occurrence of a non-recurrent laryngeal nerve is about 1 per cent, for patients undergoing thyroid surgery. Other surgically relevant anatomical variations of the recurrent laryngeal nerve include associations with the inferior thyroid artery and the presence of nerve branches. CONCLUSION: The recurrent laryngeal nerve must be carefully dissected and totally exposed during thyroid surgery in order to best preserve its function. Moreover, the thyroid surgeon must be aware of the existence of anatomical variations, which are not as rare as one may think.

[Ankyloglossum superius: apropos of a case]. / Ankyloglossum superius: à propos d'une observation.

The authors report a rare observation of ankyloglossum superius i.e. the attachment of the tip of the tongue to the anterior part of the palate, with an ectrodactyl of the fingers and toes. Following a review of the literature, this provide an opportunity to recall this pathology, the physiopathogenesis of which remains unknown falling within syndromes of malformation affecting both the mouth, face and limb, namely orofacio-digital syndromes and syndromes of hypogenesis of the mouth, jaw and limbs.