Background: Both movement (MD) and cognitive (CD) disorders can occur associated in some neurodegenerative diseases, such as Parkinson’s disease (PD) and Alzheimer’s disease (AD). Objective: We further investigated the usefulness of 123I-Ioflupane SPECT and 18F-FDG PET combined use in patients with these disorders in the early stage. Method: We retrospectively enrolled twenty-five consecutive patients with MD and CD clinical symptoms of recent appearance. All patients had undergone neurologic examination, neuropsycho- logical tests, and magnetic resonance imaging. 123I-Ioflupane SPECT was performed in all cases, followed by 18F-FDG PET two weeks later. In the two procedures, both qualitative (QL) and quan- titative (QN) image analyses were determined. Results: In patients with both 123I-Ioflupane SPECT and 18F-FDG PET pathologic data, associat- ed dopaminergic and cognitive impairments were confirmed in 56% of cases. Pathologic SPECT with normal PET in 16% of cases could diagnose MD and exclude an associated CD, despite clini- cal symptoms. On the contrary, normal SPECT with pathologic PET in 28% of cases could exclude basal ganglia damage while confirming CD. QN 123I-Ioflupane SPECT analysis showed better per- formance than QL since QN correctly characterized two cases of MD with normal QL. Moreover, correct classification of normal metabolism was made only by QN analysis of 18F-FDG PET in four cases, despite suspect areas of hypometabolism at QL. Conclusion: The combined use of these imaging procedures proved a reliable diagnostic tool to accurately identify and characterize MD and CD in early stage. QN analysis was effective in supporting QL evaluation, and its routine use is suggested, especially with inconclusive QL.

KeywordsPrimary progressive aphasia · Dementia · Brain 18 fluoro-deoxy-glucose positron emission neuroimaging Abstract Background: A primary progressive aphasia (PPA) diagnosis is generally based on clinical criteria, but often symptoms and signs may overlap in the different forms. Recent data have evidenced that brain 18 fluoro-deoxy-glucose positron emission tomography ( 18 F-FDG PET) could support the clinical diagnosis, since specific metabolic patterns are described for the different variants. Aims: We further evaluated the usefulness of 18 F-FDG PET, by both visual qualitative (QL) and quantitative (QN) methods in the initial diagnosis of PPA, focusing on the classification of different variants. Moreover, we also analyzed the role of 18 F-FDG PET in clarifying the association of PPA with the early phase of Alzheimer's disease (AD) or frontotemporal (FTD) dementias. Methods: We consecutively enrolled 35 patients with clinical symptoms of aphasia, suspect of or attributable to PPA. Patients were classified into two groups: 18 cases with clinical symptoms of aphasia but normal neuropsychological tests and an unclear classification of a specific PPA variant (group A) and 17 cases with clinical and neuropsychological signs attributable to PPA with an uncertain differential diagnosis between AD and FTD (group B). All patients underwent brain 18 F-FDG PET/CT, and images were evaluated both by QL and QN, the latter applying an automated analysis program that produced brain regional metabolic maps and normal age-matched control group comparative analysis (z score). Results: 18 F-FDG PET showed different patterns of bilateral cortical hypometabo-lism in the two groups. The combined use of QL and QN permitted to achieved a correct PPA variant diagnosis in 8 of 18 (44.4%) cases of group A and in 14 of 17 (82.3%) of group B, while only QN could support the correct classification of PPA variants in 10 of 18 (55.6%) cases of group A and in 3 of 17 (17.7%) cases of group B in whom the procedure better localized the hypometabolic areas. Conclusions: Brain 18 F-FDG PET had an elevated performance in the early diagnosis of PPA variants and in the advanced PPA AD/FTD classification. QL clarified the development of AD or FTD in advanced PPA cases and supported the differential diagnosis of a PPA variant in a few early cases. QN 18 F-FDG PET evaluation better contributed to the early diagnosis of an unclear metabolic pattern. To correctly identify all cases, patients with diffuse cortical hypometabolism were also included. Larger series are necessary to confirm these data.A total of 35 consecutive patients (15 males, 20 females, aged 53-80 years, mean ± SD value: 69 ± 6.0) with clinical symptoms of aphasia, suspect of or attributable to PPA, were enrolled retrospectively. All patients were investigated for neurological familiar diseases, neurological non-PPA affections, and generally related diseases (hypertension and diabetes mellitus). Laboratory analyses excluded secondary cognitive disorders.Neurological examinations, basal...