RECENT AND FUTURE EVOLUTIONS IN NEUROSPECT WITH PARTICULAR EMPHASIS ON THE SYNERGISTIC USE AND FUSION OF IMAGING MODALITIES

Recent and future evolutions in neuroSPECT apply to radiopharmaceutica ls techniques and the synergistic use of different imaging modalities in the work-up of neurological disorders. The introduction of Techneti um labelled perfusion tracers, which could pass the intact blood-brain barrier, together with the implementation of the tomographic principl e, by making the conventional gamma camera rotating, enabled estimatio n of regional cerebral blood flow and indirectly of local brain metabo lism. In addition at present Thallium-201 and Tc-99m sestaMIBI allow f unctional detection of viable tumor tissue, without interference from previous surgery or radiotherapy as seen using CT-scan or MRI. In neur ology this has led to the recognition of SPECT by the American Academy of Neurology (Therapeutics and technology subcommittee) as an establi shed or promising tool in major neurological disorders such as dementi a, stroke and epilepsy, while other domains such as brain oncology are considered investigational. With regard to radiopharmaceuticals, rece nt evolutions mainly include the development of mostly Iodine-123 labe lled receptor ligands, some of which are already commercially availabl e. For instrumentation advances consist e.g. of multidetector systems equipped with fanbeam collimators, attenuation and scatter correction or coincidence detection. Given the present role for nuclear neurology it may be expected that these additional radiopharmaceutical and tech nical innovations will continue to stimulate the development of SPECT of the brain. The synergistic use of several imaging techniques such a s CII: (functional) MRI, source imaging, SPECT and PET represents a mu ltimodal holistic approach to probe cerebral functions for research an d clinical purposes. Clinical indications, in which this synergistic u se is illustrated include e.g. support of the clinical diagnosis of de mentia of the Alzheimer type, presurgical ictal detection of seizure f onts, detection of acute ischemia and differential diagnosis between r adiation necrosis and brain tumor recurrence. The synergistic use of i maging modalities, optimally applied using image fusion, allows to ove rcome the intrinsic limitations and to enhance the specific advantages of the different approaches as it leads to increased precision and ac curacy, as well for spatial anatomofunctional correlation as for quant ification.