ABSTRACT
Several diseases may cause non-specific MR signal abnormalities of the bilateral basal ganglia and thalami. As such, diagnosis of the underlying etiology may be difficult to achieve at imaging. In this review, we will present interpretative guidelines based on clinical data (mode of presentation, previous history, clinical symptoms, and evolution) and imaging data (type of signal abnormalities, location of lesions, and associated abnormalities). The main categories of diseases causing MR signal abnormalities of the bilateral basal ganglia and thalami in adults are reviewed: toxic, metabolic, vascular, tumoral, infectious and inflammatory diseases.
Subject(s)
Basal Ganglia Diseases/diagnosis , Thalamic Diseases/diagnosis , Adult , Humans , Magnetic Resonance ImagingABSTRACT
THE TECHNIQUE: Today, magnetic resonance imaging (MRI) is the exploration of choice for a number of central nervous system disorders. This technique, which does not use ionising rays, examines the encephalus in all its dimensions. Various sequences are used to study the cerebral parenchyma: specific sequences in T1, with or without injection of a contrast product, specific sequence in T2, and FLAIR sequence. THE RESULTS OBTAINED: The diffusion and perfusion imaging respectively reveal the movement of the water molecules and the cerebral microcirculation. Visualisation of the arteries and veins is non-invasive with magnetic resonance angiographical techniques. Study of the chemical composition of tissues (magnetic resonance spectroscopy) and of cerebral activation (functional activation imaging) will not be addressed.
Subject(s)
Brain/pathology , Magnetic Resonance Angiography , Magnetic Resonance Imaging , Arteries/pathology , Brain/blood supply , Humans , Image Enhancement , Microcirculation/pathology , Reference Values , Veins/pathologyABSTRACT
THE MRI DIAGNOSTIC SUPPORT: Magnetic resonance imaging is an efficient technique for revealing an intercranial tumor, and specifying its topography and loco-regional impact. A macroscopical approach is possible with MRI, since it distinguishes the components: tumoral tissue, cyst, necrosis and hemorrhage. DEPENDING ON THE TUMOR: Assessment of the tumoral limits is easy for extra-axial tumors. However, it is imprecise or even impossible for infiltrating intra-axial tumors. MRI specificity is low, however some lesions such as meningiomas, glioblastomas, arachnoid cysts and neurinomas are evocative.
Subject(s)
Brain Neoplasms/diagnosis , Magnetic Resonance Imaging , Brain/pathology , Cerebral Hemorrhage/diagnosis , Humans , Necrosis , Sensitivity and SpecificityABSTRACT
IN ARTERIAL ISCHEMIC PATHOLOGY: Magnetic resonance imaging is increasingly proposed for any suspicion of cerebral vascular accident. Because of its diffusion sequences, it permits the rapid diagnosis and screening of ischemic lesions and provides prognostic information. FOR OTHER CEREBRAL VASCULAR DISORDERS: Intra-parenchymatous and sub-arachnoid hemorrhages are easily revealed by MRI. Today, MRI is the most effective examination for the diagnosis of venous thrombosis and of its impact on the parenchyma.
Subject(s)
Cerebrovascular Disorders/diagnosis , Magnetic Resonance Imaging , Brain Ischemia/diagnosis , Cerebral Hemorrhage/diagnosis , Cerebral Infarction/diagnosis , Humans , Sensitivity and Specificity , Sinus Thrombosis, Intracranial/diagnosisABSTRACT
CRANIO-ENCEPHALIC TRAUMAS: Scanography remains the examination of choice. However, MRI can be useful in diagnosis of diffuse axional lesions, not clearly visualized with scanography, and for screening the subsequent lesions. INFECTIOUS OR INFLAMMATORY LESIONS: Some are very evocative with MRI: cerebral abscesses, notably herpetic encephalitis and Creutzfeldt-Jacob's disease. If multiple sclerosis is suspected, MRI is considered as the principle para-clinical examination able to confirm the diagnosis with the first episode. It also supplies data for the diagnosis of metabolic, toxic and degenerative diseases.
Subject(s)
Brain Injuries/diagnosis , Encephalitis/diagnosis , Magnetic Resonance Imaging , Meningitis/diagnosis , Neurodegenerative Diseases/diagnosis , Brain/pathology , Brain Abscess/diagnosis , Creutzfeldt-Jakob Syndrome/diagnosis , Diffuse Axonal Injury/diagnosis , Herpes Simplex/diagnosis , Humans , Multiple Sclerosis/diagnosisABSTRACT
New imaging modalities permit detailed knowledge of the anatomy of cerebral arteriovenous malformations. Magnetic resonance imaging (MRI) provides morphological data, size and topography of the nidus, anatomic relationship, as well as dynamic information particularly with the use of MR angiography. Selective and hyperselective cerebral angiography provide information about the angioarchitecture and search for associated vascular abnormalities such as aneurysms. It is therefore possible to distinguish malformations associated with a high risk of hemorrhage and to define the indications for radiosurgery.
