Target Audience
Neurosurgeons, neuro-radiologists, radiographers and radiotherapists with an interested in brain cancers.Outcome / Objectives
An understanding of which type of MR spectroscopy protocol could assist in preoperative planning or therapeutic choices.Purpose
The goal is to provide an understanding how neuro spectroscopy can assist in preoperatively defining a lesion to be a tumor, abscess or other pathology. Magnetic resonance spectroscopy (MRS) may allow radiologists and clinicians to determine tumor type, grade and margins. Assisting with pre-operative diagnosis and therapy based on the biochemical information available.Methods
There is a range of spectroscopic methods available for investigation of a brain abnormality. These include one (1) and two-dimensional spectroscopy (2-5) from a single voxel and two and three-dimensional chemical shift imaging (MRSI)(6).Discussion
The distinction between tumor and abscess (7, 8); high grade versus low grade (9); high-grade gliomas from metastases (10); glioma subtyping (11, 12)as well as prediction of survival in high-grade gliomas are all now possible. From a surgical perspective the margins of the tumor can be identified with greater accuracy than MRI as contrast agents often don’t reach the margins due to lack of blood supply(6, 13). The MRSI method, as a post-operative scan, can see residual tumor and the grade of the residual tumor identified by 2D COSY.Conclusion
The correct series of MR spectroscopy protocols, and an understanding of how to interpret the data, can provide additional information to routine imaging and assist in preoperative planning and therapy choices. Neuro-oncological surgeons need to understand these techniques to help maximise tumor resection, while minimising morbidity in an attempt to improve the quality of patient outcome(14).1. Oz G, Alger JR, Barker PB, Bartha R, Bizzi A, Boesch C, et al. Clinical proton MR spectroscopy in central nervous system disorders. Radiology. 2014;270(3):658-79.
2. Mountford C, Quadrelli S, Lin A, Ramadan S. Six fucose-alpha(1-2) sugars and alpha-fucose assigned in the human brain using in vivo two-dimensional MRS. NMR in biomedicine. 2015;28(3):291-6. 3. Ramadan S, Andronesi OC, Stanwell P, Lin AP, Sorensen AG, Mountford CE. Use of in vivo two-dimensional MR spectroscopy to compare the biochemistry of the human brain to that of glioblastoma. Radiology. 2011;259(2):540-9.
4. Thomas MA, Hattori N, Umeda M, Sawada T, Naruse S. Evaluation of two-dimensional L-COSY and JPRESS using a 3 T MRI scanner: from phantoms to human brain in vivo. NMR in biomedicine. 2003;16(5):245-51.
5. Velan SS, Lemieux SK, Raylman RR, Boling W, Hobbs GR, Spencer RG, et al. Detection of cerebral metabolites by single-voxel-based PRESS and COSY techniques at 3T. J Magn Reson Imaging. 2007;26(2):405-9.
6. Horska A, Barker PB. Imaging of brain tumors: MR spectroscopy and metabolic imaging. Neuroimaging Clin N Am. 2010;20(3):293-310.
7. Garg M, Gupta RK, Husain M, Chawla S, Chawla J, Kumar R, et al. Brain Abscesses: Etiologic Categorization with in Vivo Proton MR Spectroscopy. Radiology. 2004;230(2):519-27.
8. Himmelreich U, Accurso R, Malik R, Dolenko B, Somorjai RL, Gupta RK, et al. Identification of Staphylococcus aureus brain abscesses: rat and human studies with 1H MR spectroscopy. Radiology. 2005;236(1):261-70.
9. Wang Q, Zhang H, Zhang J, Wu C, Zhu W, Li F, et al. The diagnostic performance of magnetic resonance spectroscopy in differentiating high-from low-grade gliomas: A systematic review and meta-analysis. Eur Radiol. 2016;26(8):2670-84.
10. Server A, Josefsen R, Kulle B, Maehlen J, Schellhorn T, Gadmar O, et al. Proton magnetic resonance spectroscopy in the distinction of high-grade cerebral gliomas from single metastatic brain tumors. Acta Radiol. 2010;51(3):316-25.
11. Andronesi OC, Kim GS, Gerstner E, Batchelor T, Tzika AA, Fantin VR, et al. Detection of 2-hydroxyglutarate in IDH-mutated glioma patients by in vivo spectral-editing and 2D correlation magnetic resonance spectroscopy. Science translational medicine. 2012;4(116):116ra4.
12. Emir UE, Larkin SJ, de Pennington N, Voets N, Plaha P, Stacey R, et al. Noninvasive Quantification of 2-Hydroxyglutarate in Human Gliomas with IDH1 and IDH2 Mutations. Cancer research. 2016;76(1):43-9.
13. Price SJ, Gillard JH. Imaging biomarkers of brain tumour margin and tumour invasion. The British Journal of Radiology. 2011;84(special_issue_2):S159-S67.
14. Brodbelt A. Clinical applications of imaging biomarkers. Part 2. The neurosurgeon's perspective. The British Journal of Radiology. 2011;84(special_issue_2):S205-S8.