Abstract
Article: Use of Gray-Level Histograms to Assess Substantia Nigra Echogenicity in Transcranial Sonography Images of Parkinson Disease Patients
Authors: Rita de Cassia Leite Fernandes, MD, PhD, Ana Lucia Zuma de Rosso, MD, PhD, Maurice Borges Vincent, and Nordeval Cavalcante Araújo, MD, PhD
Category: General Sonography
Credit: 1.0 SDMS CME Credit
Objectives: After studying the article entitled “Use of Gray-Level Histograms to Assess Substantia Nigra Echogenicity in Transcranial Sonography Images of Parkinson Disease Patients,” you will be able to:
Describe the sonographic features of the substantia nigra
Evaluate the substantia nigra using transcranial duplex sonography
Explain the limitations of transcranial sonographic evaluation of the substantia nigra
In healthy individuals, the mesencephalic substantia nigra by sonography Is readily identified as strongly hyperechogenic within the brainstem Is difficult to distinguish within the brainstem Is difficult to distinguish because it is an-echoic Is readily seen as a large hyperechogenic structure
Sonographically, the mesencephalon is seen as A hyperechoic butterfly-shaped structure A hyperechoic thin, strip-like structure A hypoechoic, butterfly-shaped structure A hypoechoic thin, strip-like structure
Using transcranial sonography, approximately what percentage of patients in the study reported had inadequate temporal acoustic windows? 14% 20% 27% 30%
Studies have shown that patients with idiopathic Parkinson disease have substantia nigra hyperechogenicity in 20% to 30% of cases 40% to 50% of cases 50% to 60% of cases >65% of cases
In the study reported, the best cutoff value for the area of substantia nigra echogenicity to distinguish healthy patients from patients with Parkinson disease was 0.16 cm2 0.22 cm2 0.33 cm2 0.37 cm2
Using the appropriate cutoff value described above, the false-negative rate for detection of Parkinson disease was approximately 10% 15% 25% 29%
Comparison of substantia nigra echogenicity with subject age showed No correlation A negative correlation A positive correlation No relationship at all
Substantia nigra gray-scale mean differences between the groups reported achieved statistical significance Throughout the mesencephalon When measured at its most echogenic site In the basal cistern At no sites
In patients with Parkinson disease, disease duration was shown to be correlated with Substantia nigra echogenicity alone Mesencephalic echogenicity alone Basal cistern echogenicity Both mesencephalic and basal cistern echogenicity
The authors have hypothesized that enhanced substantia nigra echogenicity in Parkinson disease patients may be caused by Morphologic changes in the tissue affecting tissue impedances at interfaces Morphologic changes in the tissue causing homogenization Increased deposition of calcium A relative decrease in echogenicity of surrounding tissue/structures
Footnotes