Related Experiment Video
Updated: Oct 5, 2026
Digital Spatial Profiling for Characterization of the Microenvironment in Adult-Type Diffusely Infiltrating Glioma
Published on: September 13, 2022
MR-spectroscopy guided target delineation for high-grade gliomas
A Pirzkall1, T R McKnight, E E Graves
1Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA 94143-0226, USA. pirzkall@radonc17.ucsf.edu
Purpose:
Functional/metabolic information provided by MR-spectroscopy (MRSI) suggests MRI may not be a reliable indicator of active and microscopic disease in malignant brain tumors. We assessed the impact MRSI might have on the target volumes used for radiation therapy treatment planning for high-grade gliomas.
Methods And Materials:
Thirty-four patients (22 Grade III; 12 Grade IV astrocytomas) were evaluated; each had undergone MRI and MRSI studies before surgery. MRI data sets were contoured for T1 region of contrast enhancement (T1), region of necrosis, and T2 region of hyperintensity (T2). The three-dimensional MRSI peak parameters for choline (Cho) and N-acetylaspartate (NAA), acquired by a multivoxel technique, were categorized based on an abnormality index (AI), a quantitative assessment of tissue metabolite levels. The AI data were aligned to the MRI and displayed as three-dimensional contours. AI vs. T conjoint and disjoint volumes were compared.
Results:
For both grades, although T2 estimated the region at risk of microscopic disease as being as much as 50% greater than by MRSI, metabolically active tumor still extended outside the T2 region in 88% of patients by as many as 28 mm. In addition, T1 suggested a lesser volume and different location of active disease compared to MRSI.
Conclusion:
The use of MRSI to define target volumes for RT treatment planning would increase, and change the location of, the volume receiving a boost dose as well as reduce the volume receiving a standard dose. Incorporation of MRSI into the treatment-planning process may have the potential to improve control while reducing complications.
Insights
Magnetic Resonance Spectroscopy (MRS) may offer a more accurate method than standard MRI for defining active brain tumor volumes in radiation therapy planning. This could improve treatment efficacy and reduce complications.
Area of Science:
- Neuro-oncology
- Radiology
- Medical Physics
Background:
- Magnetic Resonance Imaging (MRI) is crucial for malignant brain tumor assessment.
- However, functional/metabolic information from Magnetic Resonance Spectroscopy (MRS) suggests MRI may not reliably indicate active or microscopic disease.
- This study investigates the impact of MRS on radiation therapy (RT) target volumes for high-grade gliomas.
Purpose of the Study:
- To assess the impact of MR-spectroscopy (MRSI) on radiation therapy target volumes for high-grade gliomas.
- To compare MRSI-defined active tumor volumes with standard MRI-based volumes (T1 contrast enhancement, necrosis, T2 hyperintensity).
Main Methods:
- Evaluated 34 high-grade glioma patients (22 Grade III, 12 Grade IV astrocytomas) with pre-operative MRI and MRSI.
- Contoured MRI for T1, necrosis, and T2 regions.
- Used a multivoxel MRSI technique to assess choline (Cho) and N-acetylaspartate (NAA) metabolite levels via an abnormality index (AI).
- Aligned and compared 3D AI contours with MRI-defined volumes.
Main Results:
- MRSI revealed metabolically active tumor extending beyond T2 regions in 88% of patients, by up to 28 mm.
- T2 regions underestimated microscopic disease extent compared to MRSI.
- T1 contrast enhancement suggested smaller volumes and different active disease locations than MRSI.
Conclusions:
- Incorporating MRSI into RT treatment planning can increase and relocate boost dose volumes.
- It may also reduce standard dose volumes.
- MRSI has the potential to improve tumor control and minimize treatment-related complications.