The ‘Biological Opportunity’ of Decreasing Voxel Size with Cardiac MRI and Photon-Counting CT

We don't need bigger images. We need smaller voxels.

For years, cardiac diffusion tensor MRI (DTI) has allowed us to study myocardial microstructure but at a cost.

With only four to five voxels across the ventricular wall, much of the local architecture is simply averaged away.

However, new research pushes cardiac DTI into the submillimeter era.¹ Using free-breathing in vivo imaging at 0.85 × 0.85 mm resolution, the authors introduce a voxel-scale “phenomapping” framework combining diffusivity, anisotropy and local helix angle gradients to identify distinct myocardial microstructural environments.

The most surprising finding isn't the improved image quality.
It's the biology.

Despite severe pressure overload and marked left ventricular hypertrophy, patients with severe aortic stenosis showed a largely preserved cardiomyocyte spatial organization. The myocardium remodels but not necessarily in the way we assumed.

This is an important reminder. Macroscopic remodeling does not automatically imply microstructural disarray.

This paper beautifully illustrates a broader principle in medical imaging. Increasing spatial resolution doesn't just produce prettier images. It reveals new biology.

When the voxel becomes small enough, entirely new imaging biomarkers emerge, not because the tissue changed, but because we finally stopped averaging it away.

Where PCCT Enters the Picture

This is exactly the evolution we are witnessing with photon-counting computed tomography (PCCT). Higher spatial resolution is not simply an engineering achievement. It is a biological opportunity.

As voxel size decreases, previously invisible anatomical and pathological features become measurable rather than inferred.

Whether in cardiac MRI or PCCT, the future of imaging will not be defined by sharper pictures.

It will be defined by discovering biology that conventional resolution could never reveal.

Dr. Cademartiri is the director of advanced cardiovascular imaging and photon-counting CT at the Scientific Institute for Research, Hospitalization, and Healthcare Synlab Diagnostic Network in Naples, Italy. He is also a consultant in advanced cardiovascular imaging at CDI/Centro Diagnostico Italiano in Milan, Italy.

(Editor’s note: This blog is adapted with permission from Dr. Cademartiri’s original LinkedIn post at: https://www.linkedin.com/feed/update/urn:li:activity:7489720903149293568/ )

Reference

1. Rock CA, Chen YI, Wang R, et al. Voxel-scale diffusion tensor phenomapping of the healthy and pressure-overloaded human heart. Nat Biomed Eng. 2026 Jul 24. Doi: 10.1038/s41551-026-01755-y.