Magnetic resonance spectroscopy — Revisiting the biochemical and molecular milieu of brain tumors

Abstract

BackgroundMagnetic resonance spectroscopy (MRS) is an established tool for in-vivo evaluation of the biochemical basis of human diseases. On one hand, such lucid depiction of ‘live biochemistry’ helps one to decipher the true nature of the pathology while on the other hand one can track the response to therapy at sub-cellular level. Brain tumors have been an area of continuous interrogation and instigation for mankind. Evaluation of these lesions by MRS plays a crucial role in the two aspects of disease management described above.Scope of reviewPresented is an overview of the window provided by MRS into the biochemical aspects of brain tumors. We systematically visit each metabolite deciphered by MRS and discuss the role of deconvoluting the biochemical aspects of pathologies (here in context of brain tumors) in the disease management cycle. We further try to unify a radiologist's perspective of disease with that of a biochemist to prove the point that preclinical work is the mother of the treatment we provide at bedside as clinicians. Furthermore, an integrated approach by various scientific experts help resolve a query encountered in everyday practice.Major conclusionsMR spectroscopy is an integral tool for evaluation and systematic follow-up of brain tumors. A deeper understanding of this technology by a biochemist would help in a swift and more logical development of the technique while a close collaboration with radiologist would enable definitive application of the same.General significanceThe review aims at inciting closer ties between the two specialists enabling a deeper understanding of this valuable technology.

Multivoxel magnetic resonance spectroscopy identifies enriched foci of cancer stem-like cells in high-grade gliomas

“…Multivoxel MRS combined with conventional MRI can provide information about the spatial extent and functional metabolic heterogeneity of gliomas and surrounding areas 12,28. Thus, 1 H-MRS has been widely used for diagnosing gliomas, tumor grading, and tracking the response to therapy at subcellular level 29. Choline, NAA, and creatine are the most common metabolites visualized by 1 H-MRS imaging to investigate gliomas.…”

Metabolite Levels in Paediatric Brain Tumours Correlate with Histological Features

“…Even fewer studies have been undertaken in paediatric brain tumour patients [22,23]. There is also an increasing trend in clinical studies towards the use of short echo time MRS data that can measure a larger number of metabolites, increasing the information available and allowing detailed laboratory findings to be investigated [24][25][26].…”

“…The most commonly investigated metabolites in the in vivo MRS of brain tumours are N-acetyl aspartic acid (NAA), total choline, creatine, lipids, myoinositol (mIns), glycine (Gly), taurine (Tau), glutamate, and glutamine [4,26]. Perhaps the most evidence for an association between MRS and histology is constituted by the choline metabolites, which have been linked to cell density [27,28], the Ki67 proliferation index [18,19], and nuclear shape [17,27], as well as being suggested as a marker of rapid cellular proliferation and tumour aggressiveness [23,29,30].…”

“…mIns, which can be detected reliably by short echo time MRS, is a cerebral osmolyte and has been proposed as a marker of astrocytes and gliosis [26,33]. Elevated mIns has also been shown to distinguish between grades in astrocytomas [34,35].…”

“…NAA is commonly regarded as a neuronal marker as it has been found to be preferentially highly expressed in neurons rather than glial cells [38]. In addition, in vivo MRS of normal brain displays a prominent NAA peak, whilst tumours display far less [21,26,39,40]. However, significant amounts of NAA are found in pilocytic astrocytomas [40], and its origin in these tumours remains controversial.…”