The role of SPECT scanning in a neuropsychiatry unit.

OBJECTIVES: Single photon emission computerised tomography (SPECT) studies allow the assessment of cerebral blood flow and have been increasingly used as a clinical tool in neurology and neuropsychiatry. This paper examines the contribution of SPECT to the clinical management of patients with neuropsychiatric disorders, in particular patients with atypical or early onset dementia.

METHOD: All patients admitted to an eight-bed neuropsychiatry unit in a general hospital setting who had undergone SPECT scanning over a 15-month period were reviewed. Information was collected on clinical diagnosis, neuropsychological testing, structural neuroimaging and SPECT.

RESULTS: SPECT abnormalities were present in 88% of patients. The pattern of SPECT abnormality was concordant with structural neuroimaging in 65% of patients and concordant with neuropsychological testing in 82% of patients. The sensitivity and specificity of SPECT was 89%/79% for Alzheimer's disease and 56%/79% for frontotemporal dementias.

CONCLUSIONS: SPECT results must be interpreted in the context of other clinical and diagnostic assessments. In no single case was the clinical diagnosis made solely on the basis of a SPECT result. SPECT was of maximum clinical use in the diagnosis of frontotemporal dementias and in confirming the diagnosis of Alzheimer's dementia. SPECT was valuable in Lewy body dementia, vascular dementia and head injury. Its clinical utility in other psychiatric disorders remains unclear.