Reproducibility of a Standardized Quantitative Analysis Using Fixed Regions of Interest to Differentiate Movement Disorders on 123I-FP-CIT SPECT

The present prospective study evaluated the diagnostic value of a standardized analysis of (123)I-N-omega-(fluoropropyl)-2beta-carbomethoxy-3beta-(4-iodophenyl)tropane (FP-CIT) SPECT studies acquired on a triple-head gamma-camera for patients with clinically uncertain movement disorders having tremor as the most striking feature. (123)I-FP-CIT studies were performed on 52 consecutive patients (27 male and 25 female; mean age, 49.2 y; range, 17-80 y) who had a clinical diagnosis of Parkinson's disease (PD) (n = 21), hypokinetic rigid syndrome (n = 19), dystonia (n = 8), or essential tremor (n = 4). In all patients, the final diagnosis was based on a thorough clinical examination, the family history, and a 2-y follow-up. Two independent technologists analyzed (123)I-FP-CIT studies using a standardized quantitative method applying both fixed regions of interest (ROIs) and manually drawn ROIs. The mean values from both methods were compared using the Student t test, and the intra- and intertechnologist variabilities were tested. In patients with PD, all ratios were significantly lower (P < 0.001) than those in patients with other movement disorders. No significant differences were found between the other groups tested. The manual method resulted in significantly lower values than did the standardized method (P < 0.001) and, for the putamen, showed significant differences between technologists. The standardized method showed no significant differences between technologists. The intra- and intertechnologist variabilities for this method were 0.14 +/- 0.13 (confidence value, 2.4%) and 0.19 +/- 0.18 (confidence value, 3.1%), respectively, whereas the intraclass correlation coefficients were 0.99 for 1 technologist and 0.98 for the 2 independent technologists. Our data confirm that (123)I-FP-CIT SPECT has value in the differentiation of PD from other movement disorders. Acquisition using a triple-head gamma-camera and subsequent standardized analysis using fixed ROIs result in good intra- and intertechnologist agreement and can easily be applied in clinical practice.