Aim: To assess the clinical impact of regional cerebral blood flow (rCBF) single-photon-emission computed tomography (SPECT) imaging on diagnosis and clinician diagnostic confidence in a cohort of individuals with cognitive impairment.

Materials and methods: Forty-one clinicians who referred 79 patients for a [99mTc]-hexamethylpropyleneamine oxime (HMPAO) SPECT for cognitive complaints completed a two-part questionnaire to determine the diagnosis and diagnostic confidence (using a 0-100 visual analogue scale [VAS]) before and after imaging. SPECT images were analysed using statistical parametric mapping and interpreted semi-quantitatively. Clinicians were also asked directly for their opinion on whether the imaging contributed to their diagnostic process.

Results: Diagnosis changed after imaging in 44% of cases, and confidence was significantly improved (VAS score change= +26.3±22.2) after imaging in cases where the pre-imaging confidence was low (p<0.001). Clinician confidence was not significantly different (VAS score change=-6.6±25.5) after imaging when pre-imaging confidence was moderate to high. Interestingly, a proportion of clinicians with the highest confidence levels became less certain about their diagnosis following imaging results. When asked directly, 96% of clinicians stated that the imaging contributed to the diagnostic process.

Conclusions: In a mixed clinical cognitive impairment cohort, perfusion SPECT is valued by referring clinicians and contributes to diagnostic decision making. Imaging is of particular value when diagnostic confidence is low prior to imaging.