Brain TRODAT-SPECT Versus MRI Morphometry in Distinguishing Early Mild Parkinson's Disease from Other Extrapyramidal Syndromes.

BACKGROUND AND PURPOSE The clinical differentiation of Parkinson's disease (PD) from other extrapyramidal syndromes has made a challenge in neurology. This study aimed to compare the specificity and sensitivity of brain MRI volumetry and dopamine transporter scans in differentiating PD from other extrapyramidal syndromes in the early stages of the disease. METHODS This study included 34 patients younger than 70 years old with less than 3 years of extrapyramidal symptoms. Demographic and clinical history of the patients, including age, sex, and disease duration, was gathered. Disease severity was assessed using Unified Parkinson's Disease Rating Scale III (UPDRS III). For all patients, 99m Tc-TRODAT single-photon emission computed tomography (SPECT) and MRI volumetry were performed. Patients were followed up for 1 year and examined for final diagnosis. RESULTS According to the quantitative 99m Tc-TRODAT analysis, all of the specific binding ratio (SBR) parameters, including right, left, and bilateral SBRs, were significantly higher in the non-Parkinsonian patients. Also, the results indicated a high diagnostic accuracy for both quantitative 99m Tc-TRODAT analysis (about 88% for SBR parameters) and MRI volumetry (71% for bilateral olfactory bulbs volume) in diagnosing PD. Regarding the diagnosis of PD, there were no significant differences between quantitative scan results and olfactory bulb volumetry according to the area under the receiver operating characteristic curves. CONCLUSION 99m Tc-TRODAT has a higher accuracy in differentiation of early PD from non-Parkinsonian conditions, particularly essential tremor. Olfactory bulbs volumetry by using MRI can also serve as a potential alternative method in this regard.