Medical magnetic source imaging

Magnetic resonance imaging of the brain provides the clinical radiologist with exquisite anatomic detail of the patient's intracranial structures. Many gross pathological conditions are identifiable either by recognition of associated morphological or contrast-related changes. Angiography provides intricate depiction of intracranial vasculature and again provides vital diagnostic information related to abnormal cerebral blood supply. However, even with these techniques, we are left ignorant of functional organization and tissue viability. Half a century ago, Penfield and others proposed a homuncular cortical organization of sensory, motor and perceptive processing areas [l]. Subsequently many studies have addressed the complex networking and communication pathways between such centers, that make up the functional brain. In the past 20 years, these studies have been revolutionized with the advent of non-invasive imaging techniques which can be made sensitive to functional activity. Positron emission tomography (PET), single photon emission computed tomography (SPECT) and "functional" MRI (fMRI) may all provide images related to regional cerebral blood flow, shown to increase in appropriate cortical areas in response to peripheral activation