Amide proton transfer weighted imaging in pediatric neuro-oncology: initial experience

Area of Science:

• Radiology
• Medical Imaging
• Neuro-oncology

Background:

• Amide proton transfer weighted (APTw) imaging detects chemical exchange saturation transfer, assessing mobile proteins and peptides in vivo.
• APTw imaging has shown potential in adult brain tumors, but its utility in pediatric brain tumors requires investigation due to biological differences.

Purpose of the Study:

• To investigate the radiological appearance of pediatric brain tumors using APTw imaging.
• To assess the repeatability of APTw imaging in pediatric populations.
• To compare APTw signal intensities between tumor tissues and normal-appearing white matter, and between different pediatric brain tumor subtypes.

Main Methods:

• APTw imaging was performed at 3 Tesla, with maps calculated using magnetization transfer ratio asymmetry at 3.5 ppm.
• Repeatability was assessed using within-subject coefficient of variation (wCV) in a phantom and healthy volunteers.
• APTw levels were retrospectively analyzed in 23 pediatric brain tumor patients, comparing tumor vs. normal-appearing white matter (NAWM) and pediatric high-grade glioma (pHGG) vs. pediatric low-grade glioma (pLGG).

Main Results:

• APTw imaging demonstrated repeatability in most brain regions (wCV 11-39%), with some variability in the pontine region (39-50%).
• Significantly higher APTw values were observed in tumor tissue compared to NAWM for both pHGG and pLGG (p < 0.05).
• The pLGG subtype pilocytic astrocytoma showed higher APTw values compared to other pLGG subtypes (p < 0.05).

Conclusions:

• APTw imaging is a repeatable technique in pediatric brain regions, supporting its clinical application.
• APTw imaging can non-invasively differentiate pediatric brain tumors from normal white matter.
• APTw imaging may help characterize pediatric brain tumor biology, potentially aiding radiologists in clinical decision-making.