| Abstrakt: |
Aims and Objectives: To evaluate the diagnostic utility of Technetium 99m labelled tropane derivative Dopamine Transporter (99m Tc-TRODAT), Single photon emission computerized tomogaphy (SPECT-CT), Flourodeoxy glucose positron emission tomography (FDG-PET-CT), and magnetic resonance imaging (MRI) scans as objective evidence in patients suffering from Parkinsonism. Materials and Methods: A total of 49 (male -- 24, female -- 25) clinically diagnosed cases of parkinsonism by standard clinical criteria (Parkinson's Disease (PD) [10], Progressive Supranuclear Palsy (PSP) [14], Multiple System Atrophy (MSA)-P [9], MSA-C [2], and Cortico Basal Ganglionic Degeneration (CBGD) [14]) referred from a specialist movement disorder neurologist's clinic are included in our study. They underwent three scans -- FDG PET-CT, MRI brain, and 99mTc-TRODAT SPECT-CT -- on different days of the week after receiving proper instructions and giving informed consent. Retrospective imaging data (FDG brain PET, MRI brain, and TRODAT scans) from May 2010 to June 2016 was collected from the institution's picture archiving and communication system (PACS) server. Prospective imaging data was collected and evaluated from June 2016 to May 2018. Blinded expert visual analyses of brain PET, MRI, and TRODAT scans were done. Computer-assisted 3D System Service Processor (SSP) images of cortex ID software of FDG brain PET were also studied. The imaging diagnosis was compared with the initial clinical diagnosis at the time of referral for the scans. Results: Blinded expert visual reading of the FDG-PET images resulted in 73.4% concordance with the clinical diagnosis in all subjects in our study. Blinded expert visual reading of the MR images resulted in 42.8% concordance with the clinical diagnosis in all subjects in our study. Characteristic FDG patterns in different parkinsonism disorders are as follows: • PD is characterized by a posterior temporoparietal, occipital, and sometimes frontal hypometabolism (especially in PD with cognitive impairment) and relative hypermetabolism of putamen, pallidum, thalamus sensorimotor cortex, pons, and cerebellum. • MSA patients show a marked hypometabolism of (posterior) putamen, pons, and cerebellum, which may be more pronounced in striatum or in pons and cerebellum, depending on the predominant side of degeneration and, thus, clinical presentation (striatonigral/MSA-P and olivopontocerebellar/MSA-C, respectively). • In case of PSP, regional hypometabolism is consistently noted in medial, dorsal, and ventrolateral frontal areas (i.e., anterior cingulate gyrus, supplementary motor area [SMA], precentral gyrus, premotor to posterior prefrontal areas), caudate, thalamus, and upper brain stem. • Finally, CBS is characterized by highly asymmetric hypometabolism of frontoparietal areas, striatum, and thalamus contralateral to the most affected body side. Cortical hypometabolism may be pronounced in the parietal cortex and usually extends across the sensorimotor cortex into the cingulate gyrus and premotor to posterior prefrontal areas. All the patients diagnosed clinically as parkinsonism (PD and atypical parkinsonian syndrome (APS)) were identified correctly by TRODAT scan. In this case, sensitivity and positive predictive value were 100%, whereas specificity and negative predictive value were "indefinite." Thus, the limitation of TRODAT scan is that it could not differentiate between PD and APS (PSP/MSA-P/MSA-C/CBS). Conclusion: We conclude that FDG brain PET can be used to separate different forms of parkinsonism (PD and APS) with increased diagnostic performance, compared to MRI. The diagnostic efficacy of MRI might improve at later stages of the disease when the structural changes become more obvious. In cases of atypical presentation with clinical dilemma, a combination of 99mTc TRODAT scan followed by FDG brain PET can be done. It serves the purpose of confirming the neurodegenerative nature of parkinsonism by TRODAT and differentiation of APS into subgroups by FDG brain PET in such cases. [ABSTRACT FROM AUTHOR] |
