Objective: Our objective was to assess both exploration techniques in patients with initial IPD and verify the concordance of the findings, thus positioning them as useful biomarkers for the disease

Background: In the last years, extensive research was undertaken on possible biomarkers for Idiopathic Parkinson Disease (IPD), aimed at finding a reliable and widely available one in clinical practice. Magnetic resonance with high-resolution, iron-sensitive sequences allow direct visualization of nigrosome 1 which is most affected in SNpc of Parkinson´s patients. On the other hand, transcranial ultrasonography (TCUS) has demonstrated hyperechogenicity of SN in 90% of patients with IPD

Methods: Four (4) IPD patients (< 5 years of evolution), aged 65-79 years and 1-2 H&Y stages, were assessed. All the participants underwent MR imaging on a 1.5T magnet (Phillips, Eindhoven); axial 3D susceptibility weighted imaging (SWI) sequences were obtained and reformatted using an axial oblique plane through cerebral penduncles with a 2mm thick minimum intensity projection. Also, TCUS images were obtained (Hitachi, EUB 5500, probe 2-4 Hz) for all of them, as a part of the routine complementary initial evaluation.

All MR scans were evaluated by a 7-year experience neurorradiologist, and TCUS images by a 7-year experience neurologist, both blinded to the clinical diagnosis. Nigrosome 1 MR findings were rated as “normal”, “possibly abnormal” and “abnormal”. Hyerecogenicity of TCUS SN was determined by an area > 0,21cm2 (p90)

Results: Three (3) out of 4 patients showed concordant results in both exploration techniques (absence of nigrosome 1 and hyperechogenicity of ipsilateral SN). One of them showed hyperchogenicity (TCUS) of the SN but the MR imaging was normal. A large number of publications support the validity of MR7T and MR3T in the diagnosis of initial IPD as compared to healthy controls; however, to our knowledge, no studies have been performed with MR1.5T compared with TCUS, both techniques widely available in normal clinical practice

Conclusions: These preliminary results suggest that MR1.5T and TCUS may be useful and complementary in the evaluation of the SN degeneration in the initial phases of IPD

References:

1. Noh Y et al: Nigrosome 1 Detection at 3T MRI for the Diagnosis of Early-Stage IPD: Assessment of Diagnostic Accuracy and Agreement on Imaging Asymmetry and Clinical Laterality. AJNR Am J Neuroradiol. 2015 Nov;36(11):2010-6
2. Li DH et al: Diagnostic Accuracy of Transcranial Sonography of the Substantia Nigra in Parkinson’s disease: A Systematic Review and Meta-analysis. Sci Rep. 2016 Feb 16;6:20863

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MDS Abstracts - https://www.mdsabstracts.org/abstract/assessment-of-substantia-nigra-degeneration-with-magnetic-resonance-and-transcranial-ultrasonography/