Clinical utility of MRI and SPECT in the diagnosis of cognitive impairment referred to memory clinic

Abstract

ABSTRACTBackground:Despite of their limited availability and potential for significant variation between and within each modality, this is the first study to prospectively measure the clinical utility of MRI and/or SPECT brain scanning in addition to the routine diagnostic workup of patients presenting to memory clinic.Methods:A single center study was conducted over a convenience of 12-month sampling period. For each patient referred for MRI and/or SPECT scanning, the primary geriatrician or psychogeriatrician was asked to assign an initial diagnosis. The initial diagnosis was then compared with the final consensus diagnosis after any scans or neuropsychology testing had been completed.Results:During the 12-month study period, 66 patients (26%) were referred for scans out of a total of 253 patients included in the study. There were 16/44 (36%) positive MRI outcomes and 13/35 (37%) positive SPECT outcomes. The diagnosis changed consistent with the MRI scan findings in 11/44 (25%) and changed consistent with the SPECT scan findings in 9/35 (26%). Potentially reversible pathology was identified in a single patient, 1/50 (2%), via an MRI scan that suggested normal pressure hydrocephalus. The number needed to test for one positive outcome was 3.8 (95% CI 2.0–23.3), 6.0 (95% CI NA), and 1.7 (95% CI 1.3–2.5) for MRI only, SPECT only, and MRI and SPECT together, respectively.Conclusions:The clinical utility of MRI and/or SPECT scanning in this study may be broadly superior to the available international evidence, and further research is needed to identify predictors of positive scan outcomes.