Mesothelioma Treatment Effectiveness May Show Up Sooner with Functional Imaging

Not knowing quickly whether a mesothelioma treatment is working can be bad for you. Being in the dark causes delays in getting you switched to a treatment that might be more effective.

And the longer the delay in making such a switch, the more time there is for mesothelioma to grow. Ultimately, that makes it harder for even the ideal treatment to stop mesothelioma from progressing.

The reason treatment effectiveness or ineffectiveness can’t usually be quickly determined is that standard diagnostic and monitoring technologies don’t readily see telltale changes in mesothelioma tumors.

Researchers from the Institute of Cancer Research at Royal Marsden Hospital in the United Kingdom have been trying to do something about this shortcoming.

Writing in a recent issue of the journal Lung Cancer, they assert it may be possible to measure treatment effectiveness earlier by using functional imaging technologies rather than standard X-ray and CT scans.

Functional Imaging Has Advantages over Standard Imaging

The functional imaging technologies upon which they focused were positron emission tomography (PET), diffusion-weighted MRI (DWI) and dynamic contrast-enhanced MRI (DCE-MRI).

According to the researchers, X-ray and CT have trouble seeing tumor changes because mesothelioma tumors do not usually grow in the shape of a sphere.

X-ray and CT are great for seeing changes in most other types of cancers because those tumors are usually spherical. When those other tumors grow or shrink, X-ray and CT can easily spot that.

PET, DWI and DCE-MRI, however, are great for seeing changes in nonspherical tumors. That’s because these technologies do not look at increases or decreases in tumor size.

The researchers wrote about these three imaging modalities. They explained how each works and made the case for them as viable tools for measuring the effectiveness of mesothelioma treatments.

PET is a functional imaging technique that generates images of your body in three dimensions. It requires you first to be injected with a radioactive tracer called fluorodeoxyglucose, or simply FDG.

FDG has most of the same properties of natural glucose. Cells that need glucose to operate will gobble up any FDG that floats by in the bloodstream.

It turns out that malignant tumors have the most ravenous appetites for glucose. Mistaking the FDG for glucose, tumors greedily grab as much of it as they can. That leaves little for other cells to take up.

Since the tumors consume the lion’s share of the available FDG, it makes them stand out like a sore thumb when the PET scanner’s beam shines in their general direction.

As a result, PET can easily see whether mesothelioma tissues are thriving or retreating in response to a treatment, based on changes in their appetite for FDG.

Measuring Mesothelioma Molecular Patterns

By comparison, DWI reveals molecular diffusion in tissues. It shows the pattern of how the diffusion interacts with various fibers and membranes.

The molecular-level patterns present in this diffusion allow doctors to see the tiniest details about a targeted tumor.

DWI hasn’t been used much in cancer management monitoring. Mainly it’s used to manage patients in the aftermath of a stroke.

However, there is a small but insistent movement brewing to make DWI the gold standard for cancer management monitoring.

Then there is DCE-MRI. It involves analysis of the blood vessels formed by tumors. This imaging method requires injection of a gadolinium-based contrast agent. But before that, an MRI is taken of the tumor.

Another MRI is taken after the contrast agent is injected. Comparing the two images allows the measurement of how much contrast agent has passed through the tumor’s extracellular tissue space.

If the tumor is growing, less contrast agent will have passed through the extracellular tissue space than would be the case if the tumor were shrinking.

Each of these imaging techniques offers hope to mesothelioma patients who need to know that the treatments they receive are, in fact, helping.