Advanced Neurological Imaging Techniques

NIISwa performs many advanced neurological imaging techniques in CT and MRI which assist in the diagnosis and further characterisation of neurological conditions and their associated treatment options. Some examples are listed below:

Computed Tomography (CT) Advanced Neuro Imaging

Computed Tomographic Angiography (CTA) provides angiographic like images of the cerebral blood vessels using an intra venous contrast injection and thin-section dynamic CT scanning. Various 3-dimensional display techniques, including shaded surface display, volume rendering, and maximal intensity projection, are used to complement the conventional transaxial images. Such studies provide multiple projections of anatomically complex vascular lesions and delineate their relationships to adjacent structures.

CT Perfusion is a relatively new technique that allows the evaluation of cerebral blood perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) following the injection of a small amount of intravenous contrast media. CT acquisition over time through a section of the brain is used to construct perfusion maps. CT Perfusion is useful in the non-invasive diagnosis of early stroke, evaluation of vasospasm in patients not suited to Trans Cranial Doppler (TCD) and in tumour/ radiation necrosis changes.

NIISwa advocates the ALARA principle (As Low as Reasonably Achievable) in all cases involving radiation i.e. many dose reduction strategies in both CT and angiography procedures are implemented whilst maintaining image quality.

Magnetic Resonance (MR) Advanced Neuro Imaging

MR Perfusion is the MR technique allowing evaluation of cerebral blood volume (CBV) following the injection of gadolinium contrast media followed by MR imaging over time. This technique is often used in the further evaluation of tumours and stroke.

Susceptibility weighted imaging is a high resolution MR technique that is more sensitive than conventional imaging in detecting haemorrhagic lesions

MR spectroscopy acquires metabolite information reflecting neuronal integrity and function from multiple brain regions and provides sensitive, non-invasive assessment of changes in neurochemical behaviour. It can be used to further characterise lesions such as tumours, epilepsy and other diseases such as schizophrenia and multiple sclerosis.

Diffusion weighted imaging is based on differences in diffusion of water molecules within the brain and is very sensitive in the detection of stroke

Diffusion tensor imaging (DTI) is a form of diffusion weighted imaging and allows better evaluation of white matter fibre tracts by taking advantage of the directional diffusion of water in the human brain. It is very useful in the evaluation of brain tumours and other neurological diseases.

Functional MRI (fMRI) is a specialised MRI scan that measures the change in blood flow related to a neuronal activity. Patients are asked to perform specific tasks eg finger tapping, word association with pictures etc during the MRI scan and activation centres of the brain can be seen. This is useful particularly in the pre operative evaluation of brain tumours and epilepsy.

Arterial Spin Labelling (ASL) is a new non invasive, non contrast method of calculating cerebral brain perfusion by imaging pre magnetised proximal blood as it enters the brain. The associated signal is proportional to cerebral blood flow.

More Information

Further reading on CT and MRI scanning can be found in the Consumer Information section of the Diagnostic Imaging Pathways website.

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Computed Tomographic Angiography (CTA) provides angiographic like images of the cerebral blood vessels using an intra venous contrast injection and thin-section dynamic CT scanning. Various 3-dimensional display techniques, including shaded surface display, volume rendering, and maximal intensity projection, are used to complement the conventional transaxial images. Such studies provide multiple projections of anatomically complex vascular lesions and delineate their relationships to adjacent structures.

 

 

CT Perfusion is a relatively new technique that allows the evaluation of cerebral blood perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) following the injection of a small amount of intravenous contrast media. CT acquisition over time through a section of the brain is used to construct perfusion maps. CT Perfusion is useful in the non-invasive diagnosis of early stroke,   evaluation of vasospasm in patients not suited to Trans Cranial Doppler (TCD)   and in tumour/ radiation necrosis changes.

 

NIISwa advocates the ALARA principle (As Low as Reasonably Achievable) in all cases involving radiation i.e. many dose reduction strategies in both CT and angiography procedures are implemented whilst maintaining image quality.