250 AUDIT OF MEMORY CLINIC PATIENTS RECEIVING INDETERMINATE FDGPET BRAIN REPORTS IN ORDER TO ESTABLISH CURRENT CARE

Abstract

Abstract Background Current clinical diagnostic criteria may not be sensitive or specific enough to aid early diagnosis of dementia causing diseases. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) computed tomography (CT) brain scans are recommended in cases of diagnostic uncertainty, with patterns of reduced FDG uptake indicating dementia causing diseases eg Alzheimer’s disease. Unfortunately, scans can be reported as indeterminate. This audit aimed to identify those with indeterminate results and review clinical follow-up and subsequent diagnoses. Methods FDGPET scans requested by our service between 01/01/2015 to 31/12/2018 were identified and reviewed (n = 134). Results were initially classed as ‘indeterminate’ if a) there were any areas of reduced FDG uptake reported and b) these were insufficient to constitute a pattern typical of a dementia causing disease (n = 73). The radiology team subsequently reviewed the list and determined n = 22 as being definitively indeterminate, the remaining n = 51 reporting only minor, mild changes. FDGPET z scores for parietal and post-cingulate areas (quantified by General Electric using the CortexID programme) were reviewed, and deemed significant if >2. Electronic care records were analysed to establish subsequent clinical follow-up and diagnoses. Results The age range of patients was 56–85 years (mean 73.3), 15/22 were female. All n = 22 patients had areas of reduced FDG uptake in the temporoparietal region. All patients with indeterminate scan results had further outpatient follow up. The most recent clinical information, collected January and March 2021, showed 20 patients had developed dementia (11/20 had parietal z scores >2) and 2 had diagnoses of mild cognitive impairment (bilateral parietal and post-cingulate z scores <2). Conclusion The majority of patients with indeterminate findings on FDGPETCT in our cohort developed dementia. Patients with indeterminate findings on FDGPETCT, in particular parietal z scores above 2, should be followed up.