Lukas Lundholm: Early treatment response detectable with MR imaging

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Lukas Lundholm: Early treatment response detectable with MR imaging

Lukas Lundholm: Early treatment response detectable with MR imaging

Published

26 May 2025

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Lukas Lundholm’s doctoral thesis demonstrates how MR imaging can reveal microscopic changes in cancer tissue just a few days after the start of radiation therapy. The method could ultimately support earlier and more accurate treatment decisions.

Lukas Lundholm, medical physicist and doctoral student at the Institute of Clinical 91̽��s.

LUKAS LUNDHOLM
Dissertation defense: 13 June 2025 (click for details)
Doctoral thesis:
Research area: Medical Radiation 91̽��s
Sahlgrenska Academy, The Institute of Clinical 91̽��s

Diffusion-weighted magnetic resonance imaging (MRI) is an imaging technique that measures how water molecules move within tissue. In his thesis, Lukas Lundholm shows how a specific MRI technique called VERDICT can be used to detect early effects of radiation therapy in cancer tissue.

“We observed significant changes in several microscopic parameters just three days after the start of treatment,” says Lukas Lundholm, medical physicist and doctoral student at the Institute of Clinical 91̽��s.

The results open up the possibility of evaluating treatment response much earlier than with current methods, which usually rely on visible shrinkage of the tumor.

Cover image of the thesis: Illustration of magnetic fields and molecular motion in cells. Painting by Lena Lundholm.

Can classify tumor tissue types

VERDICT stands for “vascular, extracellular and restricted diffusion for cytometry in tumors” and is based on modeling the MR signal according to the microstructure of the tumor tissue. By fitting the model to the acquired MR data, it is possible to estimate parameters such as cell radius, cell density, and the diffusion of water molecules inside and around the cells.

One of the studies also showed that it can be used to classify different types of tumor tissue.

“In the long run, the method could support earlier and improved evaluation of radiation therapy and lead to more accurate and personalized treatment decisions. If we see that the treatment has no effect after just a few days, we can quickly switch strategies instead of waiting several weeks to see if the tumor starts to shrink,” says Lukas Lundholm.

Figure from the thesis: Colormaps of VERDICT parameters in a tumor model at different time points after radiation treatment. Clear changes are visible only a few days after treatment.

Proposing improvements to the method

The thesis also explores how the method can be improved. Through theoretical simulations, Lukas Lundholm showed that certain simplified assumptions in the model—for example, regarding how water moves around and between cells—can lead to systematic errors. Several methodological improvements are therefore proposed in the thesis.

“It is about making the model more flexible so that it better reflects reality. This increases the reliability of the results when we want to use the method in clinical practice.”

Figure from the thesis: Simulation of water diffusion around circular cells. Depending on how long the molecules diffuse, their motion becomes sensitive to different levels of the microstructure – a principle utilized in the VERDICT method.

Multiple settings—and many collaborations

The project spanned several research environments: preclinical animal studies, clinical examinations in patients, and computer simulations.

“It was a challenge to get familiar with all these settings and research approaches, but at the same time it was both fun and educational. What I’ve especially appreciated is meeting so many kind and knowledgeable people. Research really becomes exciting when people with different areas of expertise work together.”

Text: Jakob Lundberg

Area

Health and medicine