Correlation of Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy of Basal Ganglia with APGAR Score in Perinatal Asphyxia: A Cross-sectional Study

Abstract

Introduction: Birth asphyxia is leading cause of perinatal and neonatal mortality and morbidity especially in developing countries. Around 20% of neonatal deaths in India are due to birth asphyxia. There are around one million cases of birth asphyxia per year worldwide. Majority of deaths and disabilities can be prevented by timely identification of pathologies and early initiation of rehabilitation. Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) plays a vital role by helping in identification of such pathologies. Aim: To assess the severity of injury to brain in hypoxic ischaemic encephalopathy infants using MRI and MRS which helps in prognosticating the disease outcome. Materials and Methods: A cross-sectional study was conducted on 30 term infants with low Appearance, Pulse, Grimace, Activity, and Respiration (APGAR) score in the Department of Radiodiagnosis, from all the Hospitals attached to Bangalore Medical College and Research Institute, Bengaluru, Karnataka, India from November 2018 to May 2020. Patients were subjected to brain MRI and basal ganglia MRS. All MR imaging examinations were performed on a SIEMENS magneto Avanto 1.5 Tesla system. Conventional MR imaging findings were documented and MR spectroscopy values of Basal Ganglia (BG) N-Acetyl Aspartate (NAA), Creatinine (Cr), Choline (Cho) and lactate were obtained. Metabolite levels were correlated with APGAR scores by performing Pearson correlation. Chi-square test was applied with Fisher’s-exact correction to see the association between lactate peak and diffusion changes in brain. Results: A total of 30 term neonates with low APGAR score at birth were selected, of which 12 were females and 18 were males. Babies with APGAR score of 2 at one minute showed only subcortical and parasagittal areas of diffusion restriction. Basal ganglia diffusion restriction is noted only in babies with very low APGAR score of 1 at one minute. Positive correlation was noted between APGAR score and BG-NAA and BG-Cr. Negative correlation was noted between BG-Cho and APGAR score. Hence, BG-NAA:Cr, NAA:Cho and Cho:Cr can be used to assess severity of hypoxic ischaemic encephalopathy (p-value <0.001). Conclusion: Basal ganglia is a sensitive region in defining asphyxia related metabolite abnormalities. Involvement of basal ganglia and thalamus indicates severe asphyxia. BG metabolite levels may alter even in the absence of brain changes on MR imaging. Presence of lactate peak indicates severe asphyxia. Thus, MRS helps in early diagnosis of birth asphyxia, grading of its severity and prognostication.

Keywords

• appearance pulse grimace activity and respiration score
• hypoxic ischaemic encephalopathy
• n-acetyl aspartate
• perirolandic area