Meningioma- most common tumour of the menings ! on MRI ! скачать в хорошем качестве

Meningioma- most common tumour of the menings ! on MRI !

. Plain radiograph Plain films no longer have a role in the diagnosis or management of meningiomas. Historically a number of features were observed, including: enlarged meningeal artery grooves hyperostosis or lytic regions calcification displacement of calcified pineal gland/choroid plexus due to mass effect CT CT is often the first modality employed to investigate neurological signs or symptoms, and often is the modality which detects an incidental lesion: non-contrast CT 60% slightly hyperdense to normal brain, the rest are more isodense 20-30% have some calcification  50% demonstrate variable adjacent oedema (see below)  post-contrast CT 72% brightly and homogeneously contrast enhance malignant or cystic variants demonstrate more heterogeneity/less intense enhancement hyperostosis (5%)  typical for meningiomas that abut the base of the skull need to distinguish reactive hyperostosis from: direct skull vault invasion by adjacent meningioma primary intraosseous meningioma enlargement of the paranasal sinuses (pneumosinus dilatans) has also been suggested to be associated with anterior cranial fossa meningiomas 19 lytic/destructive regions are seen particularly in higher grade tumours but should make one suspect alternative pathology (e.g. haemangiopericytoma or metastasis) ref MRI As is the case with most other intracranial pathology, MRI is the investigation of choice for the diagnosis and characterisation of meningiomas. When appearance and location are typical, the diagnosis can be made with a very high degree of certainty. In some instances, however, the appearances are atypical and careful interpretation is needed to make a correct preoperative diagnosis. Meningiomas typically appear as extra-axial masses with a broad dural base. They are usually homogeneous and well-circumscribed, although many variants are encountered. It seems that the signal intensity of meningiomas on T2-weighted images correlates with the histological subtypes 27. Signal characteristics Signal characteristics of typical meningiomas include: T1 usually isointense to grey matter (60-90%) 3,8,13 hypointense to grey matter (10-40%): particularly fibrous, psammomatous variants T1 C+ (Gd): usually intense and homogeneous enhancement T2 usually isointense to grey matter (~50%)  hyperintense to grey matter (35-40%) usually correlates with a soft texture and hypervascular tumours  seen in microcystic, secretory, cartilaginous (metaplastic), chordoid and angiomatous variants  hypointense to grey matter (10-15%): compared to grey matter and usually correlates with harder texture and more fibrous and calcified contents DWI/ADC: grade 2 and 3 tumours may show greater than expected restricted diffusion although this is not universally useful in prospectively predicting histological grade  MR spectroscopy: usually does not play a significant role in diagnosis but can help distinguish meningiomas from mimics. Features include: increase in alanine (1.3-1.5 ppm) increased glutamine/glutamate increased choline (Cho): cellular tumour absent or significantly reduced N-acetylaspartate (NAA): non-neuronal origin absent or significantly reduced creatine (Cr) MR perfusion: good correlation between volume transfer constant (k-trans) and histological grade MR tractography: allows the identification of white matter tracts adjacent to the meningioma this may aid in preoperative planning for meningioma resection by allowing planning of a safer access route that would result in less residual functional iatrogenic deficits​ #radiology #case #learning #radio #ctscan #doctor #mri #interesting #ultrasound #brain #mri #meningioma #meninges #tumor #carcinoma