Physiological imaging-defined, response-driven subvolumes of a tumor

Area of Science:

• Radiology
• Oncology
• Medical Imaging Analysis

Background:

• Tumor heterogeneity impacts treatment response and patient outcomes.
• Accurate assessment of tumor subvolumes is crucial for personalized therapy.
• Physiological imaging parameters offer insights into tumor biology.

Purpose of the Study:

• To develop an image analysis framework for delineating tumor subvolumes based on physiological imaging.
• To correlate these subvolumes with treatment response and patient outcomes.
• To evaluate the framework's utility in predicting response to whole-brain radiation therapy (WBRT).

Main Methods:

• Developed a novel approach to delineate tumor subvolumes using heterogeneous physiological imaging parameters.
• Applied the method to regional cerebral blood volume (rCBV) and K(trans) images in brain metastases patients undergoing WBRT.
• Analyzed changes in rCBV-defined subvolumes from pre-treatment to 2 weeks post-WBRT to differentiate tumor response.

Main Results:

• A significant decrease in high rCBV-defined subvolumes from pre-RT to 2W was observed in responsive tumors compared to stable/progressive tumors (P<.007).
• Changes in high rCBV subvolumes predicted post-RT response better than gross tumor volume changes (P=.012), indicating early physiological changes.
• Gd-DTPA transfer constant (K(trans)) did not provide significant additional discriminatory information over rCBV.

Conclusions:

• Physiological imaging-defined tumor subvolumes delineated by this method show promise for identifying treatment response.
• These subvolumes may serve as candidates for targeted radiation therapy boosts.
• Further development and validation of this imaging framework are warranted.