RT Journal Article
SR Electronic
T1 Reproducibility and diagnostic accuracy of substantia nigra sonography for the diagnosis of Parkinson's disease
JF Journal of Neurology, Neurosurgery & Psychiatry
JO J Neurol Neurosurg Psychiatry
FD BMJ Publishing Group Ltd
SP 1087
OP 1092
DO 10.1136/jnnp.2009.196352
VO 81
IS 10
A1 van de Loo, Simone
A1 Walter, Uwe
A1 Behnke, Stefanie
A1 Hagenah, Johann
A1 Lorenz, Matthias
A1 Sitzer, Matthias
A1 Hilker, Rüdiger
A1 Berg, Daniela
YR 2010
UL http://jnnp.bmj.com/content/81/10/1087.abstract
AB Objective Transcranial sonography (TCS) shows characteristic hyperechogenicity of the substantia nigra (SN) in patients with Parkinson's disease (PD). Although this feature is well established, sufficient observer reliability and diagnostic accuracy are prerequisites for advancements of this method.Methods The authors investigated both aspects in a cross-sectional study with four blinded TCS raters in 22 PD patients and 10 healthy controls.Results As expected, the authors found significant bilateral SN hyperechogenicity in PD patients. Quantitative computerised SN planimetry had a substantial intra- (intraclass correlation coefficient (ICC) 0.97 and 0.93 respectively for both hemispheres) and inter-rater reliability (ICC 0.84 and 0.89), while visual semiquantitative echogenicity grading of the SN revealed a moderate intrarater (weighted kappa 0.80 ipsilateral and 0.74 contralateral) and slight (0.33) to fair (0.51) inter-rater reliability only. Diagnostic accuracy measured as the area under the curve of receiver-operating characteristics plots was highest in TCS of the SN opposite the clinically most affected body side (planimetry 0.821, echogenicity grading 0.792) with a hyperechogenic area of 0.24 cm2 as the optimum cut-off value for the differentiation between PD and controls (sensitivity 79%, specificity 81%).Conclusions The data demonstrate that the observer variability of SN planimetry is low in the hands of experienced investigators. This approach also offers adequate diagnostic accuracy. The authors conclude that reliable SN TCS data on PD can be achieved in clinical routine and multicentre trials when standardised analysis protocols and certain quality criteria of brain parenchyma sonography are met.