# Evaluation of Partial Volume Correction Techniques for Sodium MRI of the Achilles Tendon

## TL;DR

This paper compares different methods to correct for partial volume effects in sodium MRI scans of the Achilles tendon, finding that a new method called eSTC gives the most accurate results.

## Contribution

The novel eSTC method for partial volume correction in sodium MRI is introduced and shown to outperform existing techniques.

## Key findings

- All PVC methods improved accuracy compared to no correction, with eSTC showing the smallest difference in simulated data.
- In vivo results showed eSTC and GTM reduced resolution-related aTSC differences to less than 8 mM, compared to 38.8 mM without correction.
- The eSTC method produced the most accurate apparent tissue sodium content calculations for Achilles tendon imaging.

## Abstract

To evaluate partial volume correction (PVC) techniques for sodium MRI of the Achilles tendon in situ and in vivo.

Five PVC methods were evaluated including a volume ratio of the proton and sodium segmentations (PSSR), a modified least trimmed square (3D‐mLTS) linear regression, a geometric transfer matrix (GTM) approach, a single target correction (STC), and a novel estimated single target correction (eSTC). Their performance was tested using simulated data and 3 T MR data of two volunteers' Achilles tendons acquired at different resolutions: 1.5, 2.0, 3.0, and 4.5 mm3. Since there was no in vivo ground truth, the highest‐resolution apparent tissue sodium contents (aTSC) were used.

In the simulation, all PVC methods reduced the difference between the actual and calculated concentrations and were 11.69 ± 6.17 mM without PVC, 4.90 ± 5.40 mM with the PSSR, 4.86 ± 5.19 mM with the mLTS, 1.72 ± 4.13 mM with the GTM, 0.36 ± 1.77 mM with STC and 0.26 ± 1.63 mM with the eSTC. In vivo, the difference in aTSCs between the lower and the highest resolution decreased with all PVCs ranging from 3.6 to 38.8 mM without PVC, 2.8–20.4 mM with PSSR, 4.5–25.9 mM with mLTS, 0.9–7.8 mM with GTM, 0.1–23.8 mM with STC, and 0.7–7.7 mM with eSTC.

PVC generally improved the accuracy of aTSC calculations. The newly introduced eSTC produced the most accurate results for the Achilles tendon.