Radiotracer imaging of dopamine transporters and presynaptic dopamine synthesis in parkinsonian syndromes

Transcranial sonography and (123)I-FP-CIT single photon emission computed tomography in movement disorders

Diagnosis of Parkinson's disease (PD) can be difficult in the early stages of the disease. The aim of the study described here was to assess the correlation between transcranial sonography (TCS) and (123)I-FP-CIT ([(123)I]ioflupane, N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-[(123)I]iodophenyl)nortropane) SPECT (single photon emission computed tomography) findings and the diagnosis of PD. A total of 49 patients were enrolled in the study: 29 patients with PD, 7 patients with other parkinsonian syndromes, 11 patients with essential tremor and 2 with psychogenic movement disorder. Substantia nigra echogenicity was measured using TCS. SPECT was performed using DaTSCAN ([(123)I]ioflupane). TCS and SPECT findings were correlated in 84% of patients, with κ = 0.62 (95% confidence interval: 0.38-0.86). TCS-measured substantia nigra echogenicity and SPECT-measured striatal binding ratio were negatively correlated (r = -0.326, p = 0.003). TCS/SPECT sensitivity, specificity and positive and negative predictive values for the diagnosis of PD were 89.7%/96.6%, 60.0%/70.0%, 76.5%/82.4% and 80.0%/93.3%, respectively. Both positive TCS and SPECT findings correlated significantly with the diagnosis of PD (κ = 0.52, 95% confidence interval: 0.27-0.76, and κ = 0.69, 95% confidence interval: 0.49-0.90, respectively).