Evaluation of the Lactate-to-N-Acetyl-aspartate Ratio Defined With Magnetic Resonance Spectroscopic Imaging Before Radiation Therapy as a New Predictive Marker of the Site of Relapse in Patients With Glioblastoma Multiforme

Multimodality Brain Tumor Imaging: MR Imaging, PET, and PET/MR Imaging

“…In a phase II cohort of patients with glioblastoma, MRS has been used with an elevated Cho/NAA threshold of 2:1 to target areas of high malignancy within the non-enhancing zone adjacent to the post-resection surgical bed with a stereotactic radiosurgery boost in addition to standard conformal radiotherapy, resulting in prolonged survival compared to historical controls treated with standard therapy alone(14). In another phase II cohort of newly diagnosed glioblastoma, a Lac/NAA ratio of ≥0.4 within voxels prior to radiation therapy was significantly predictive of local tumor recurrence(15). Longitudinal changes in Cho and NAA metabolite ratios assessed within enhancing tumor and in the tumor periphery have also shown potential for early response assessment in patients with recurrent glioblastoma undergoing anti-angiogenic therapy(16), a common situation in the value of gadolinium-enhancement alone as a marker for disease response may be diminished.…”

Glioblastoma multiforme: emerging treatments and stratification markers beyond new drugs

“…Therefore, lactate imaging might also serve as a biological targeting or dose-painting technique. 80 Although including only small patient numbers so far, longitudinal trials considering the correlation of patterns of recurrence with respect to MRSI and in comparison to the conventional MRI pattern before radiotherapy are indispensable before treatment-planning approaches may be adapted. On this account, the results of trials investigating the implications of radiotherapy planning using MRSI are ambitiously awaited.…”

Imaging-Based Treatment Adaptation in Radiation Oncology

“…An additional option is the use of MR spectroscopy to study metabolic changes in tumors, assessing the relative concentrations of cancer cell metabolites. In a promising French study, MR spectroscopy before radiotherapy allowed stratification of patients with glioblastoma multiforme according to therapy outcome (23). Combining all data provided by functional MRI into a multiparametric dataset provides an extensive characterization of tumors, such as has been shown in prostate cancer (24).…”