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1040 Metabolite Quantification and Entity and Grade Characterisation of Gliomas via Single-Voxel Spectroscopy for Pre-Operative Radiological Diagnosis


 
 
 Brain tumours pose a diagnostic challenge, but single-voxel spectroscopy (SVS) provides a non-invasive tool to quantify brain metabolite variations reflective of neoplasia, such as NAA, choline (Cho), creatinine (Cr), lipids (Lip) and lactate (Lac). Inconsistency in spectroscopic research and time-patient pressures emphasises the need for reviewing SVS characterisation of gliomas for peri-operative decision-making.
 
 
 
 A single-centre, retrospective, observational study, including 93 SVS meaningfully interpretable examinations between 2012 and 2018 (PRESS, TE=35ms, 144ms). Spectroscopic diagnoses were compared to histopathologic reports for overall, entity and grade accuracy analysis. Metabolite ratios to Cr were recorded or obtained from peak area integrals.
 
 
 
 High accuracy of lesions discrimination was observed (83–98%). Significant metabolite variation for Cho/Cr (p=0.021) and Cho/NAA (p=0.013) was observed across grades (WHO Grade I-IV). Spectra of astrocytomas and oligodendrogliomas (grade II) were similarly characterised by high Cho, decreased NAA and Cr, and small-to-moderate Lac-Lip and mIns. In contrast, grade III anaplastic oligodendrogliomas (AO) were distinguished from anaplastic astrocytomas (AA) thanks to smaller Lac-Lip and mIns/Cr. Finally, glioblastoma multiforme (GBM, grade IV) displayed high Cho, decreased Cr, the lowest or virtually absent NAA, and the highest Lac-Lip. High-grade spectroscopy, such as enhanced Lac or Lac-Lip, may be an early indicator of grade transformation prior to reflection in histopathology in tumours, which were follow up prospectively.
 
 
 
 This study enhanced spectral characterisation of gliomas and discrimination amongst low- and high-grade gliomas. Whilst these aid pre-operative radiological diagnoses, further research is required to investigate spectroscopy predictive of tumour genetics, now necessary for diagnosis.
