ABSTRACT
We investigated in vivo brain nicotinic acetylcholine receptor (nAChR) distribution in cognitively intact subjects with Parkinson's disease (PD) at an early stage of the disease. Fourteen patients and 13 healthy subjects were imaged with single photon emission computed tomography and the radiotracer 5-[(123)I]iodo-3-[2(S)-2-azetidinylmethoxy]pyridine ([(123)I]5IA). Patients were selected according to several criteria, including short duration of motor signs (<7 years) and normal scores at an extensive neuropsychological evaluation. In PD patients, nAChR density was significantly higher in the putamen, the insular cortex and the supplementary motor area and lower in the caudate nucleus, the orbitofrontal cortex, and the middle temporal gyrus. Disease duration positively correlated with nAChR density in the putamen ipsilateral (ρ = 0.56, p < 0.05) but not contralateral (ρ = 0.49, p = 0.07) to the clinically most affected hemibody. We observed, for the first time in vivo, higher nAChR density in brain regions of the motor and limbic basal ganglia circuits of subjects with PD. Our findings support the notion of an up-regulated cholinergic activity at the striatal and possibly cortical level in cognitively intact PD patients at an early stage of disease.
ABSTRACT
OBJECTIVE: The aim of this study was to compare the accuracy of thyroid nodule volume measurements performed by 2- and 3-dimensional ultrasonography and to evaluate the dependence of volume measurement results on nodule size and echographic characteristics. METHODS: Results of multiple 2- and 3-dimensional ultrasonographic volume measurements of thyroid nodules in 102 children with different variants of thyroid nodular disease were reviewed retrospectively. The standardized difference, within-observer variability, and repeatability were estimated for both 2- and 3-dimensional ultrasonography. The mean age of the patients +/- SD in the examined group was 14.9 +/- 2.8 years; the mean volume of thyroid nodules was 0.78 +/- 0.13 mL. RESULTS: The SD of the normalized difference for 3-dimensional ultrasonography (2.8%) showed the clear superiority of its accuracy over 2-dimensional ultrasonography (15.9%; F test, P < .01). Intraobserver variability and repeatability for both examined methods had significant dependence on the nodule outline. For 2-dimensional ultrasonography, the intraobserver variability increased from 14.0% in nodules with a regular outline to 24.5% in those with an irregular outline (P < .001), and for 3-dimensional ultrasonography, it increased from 5.1% to 9.3% (P < .001). Intraobserver repeatability dropped from 85.4% in regular nodules to 74.6% in irregular nodules (P < .001) for 2-dimensional ultrasonography and from 94.7% to 90.4% (P < .001) for 3-dimensional ultrasonography. CONCLUSIONS: Volume measurements by 3-dimensional ultrasonography are more accurate, showing lower intraobserver variability and higher repeatability, than those made by 2-dimensional ultrasonography with less dependence on nodule size and echographic characteristics.
