Comparison of 6-[18F]FDOPA PET with Nigrosome 1 detection in patients with parkinsonism

Abstract

Background The functional 6-[18F]FDOPA positron emission tomography (PET) can be a helpful tool in differentiating parkinsonism with dopaminergic deficiency from clinically similar differential diagnoses. Furthermore, in T2*/susceptibility-weighted imaging (SWI) magnetic resonance imaging (MRI) sequences the structural integrity of the Nigrosome 1 (N1) can be assessed by checking the presence of the swallow tail sign (STS). We therefore retrospectively compared the performance of the 6-[18F]FDOPA PET with the N1 detection in patients suspected with parkinsonian diseases. Forty-three consecutive patients (m: 23, f: 20, mean age: 63 ± 12 years) were included in the study. They underwent clinically indicated 6-[18F]FDOPA PET/MRI scans as part of their neurological evaluation of uncertain parkinsonian syndromes. Visual and semi-quantitative PET imaging results were statistically compared with visual N1 assessment on 3 T SWI. As the gold standard, we defined the clinical diagnosis at the last follow-up, which included idiopathic Parkinson syndrome (IPS; n = 18), atypical parkinsonian syndromes (APS; n = 9) and other neurological diseases without dopaminergic deficit (n = 16). Results Thirty-five of 43 patients (81%, Kappa 0.611) had corresponding results in 6-[18F]FDOPA PET and SWI. Seven of the remaining 8 patients were correctly diagnosed by 6-[18F]FDOPA PET alone. Sensitivity, specificity and accuracy for 6-[18F]FDOPA and N1 imaging were 93%, 94%, 93% and 82%, 75%, 79%, respectively. Conclusions 6-[18F]FDOPA PET and Nigrosome 1 evaluation had an overall good intermodality agreement. Diagnostic agreement was very good in cases of clinically suspected idiopathic Parkinson syndrome and fair in atypical parkinsonian syndromes, but poor in patients with non-parkinsonian disorders. 6-[18F]FDOPA PET showed higher sensitivity, specificity and accuracy in discriminating parkinsonian syndromes from non-parkinsonian disorders than the N1 evaluation. In summary, the additional benefit of N1 assessment in patients with APS or parkinsonism without dopaminergic deficit needs to be proven by prospective studies.

The Role of Small Molecules Containing Fluorine Atoms in Medicine and Imaging Applications

“…While 18 F-fluoride nucleophilic substitution reactions remain the preferred method for [ 18 F]-labeled radiotracer production [ 116 ], electrophilic methods have been explored to enable C- 18 F bond formation in a variety of [ 18 F]-labeled compounds that are used diagnostically [ 50 , 114 , 121 , 122 , 123 , 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 ]. Recent, thorough reviews of methodologies to form C- 18 F bonds by Chen et al [ 115 ], Zhiyi and coworkers [ 132 ], and Lui et al [ 133 ] provide excellent accounts of the state of the art in the production of [ 18 F]-labeled compounds.…”

Introductory Chapter: Neurological Disorders - Therapy Approaches

“…The evaluation in ND can identify signs that suggest alteration of the nervous system and can indicate the most appropriate complementary examinations to stablish an accurate diagnosis. Among the complementary exams there are: i) imaging studies [10][11][12][13] (such as Magnetic Resonance Imaging, Computed Tomography, positron emission tomography, Ultrasonography and Doppler); ii) physiological studies (such as neurophysiological examinations [14]: electroencephalogram, electroneuromyography, evoked potentials); iii) neuropsychological tests (tests that involve interviews, questionnaire applications and specific tests, with the aim of testing areas such as attention, memory, language, reasoning, and learning); iv) analysis of cerebrospinal fluid; v) blood tests (including genetic tests, research of therapeutic levels of drugs in the body, tests for specific antibodies, and general tests for numerous other diseases that can cause neurological symptoms); and vi) biopsies (of nervous tissue, skin, or muscles). The rapid and accurate diagnosis of ND allows for early treatment, improving the quality of life and the prognosis of the disease, often being the difference between life and death [15].…”