Reply to “Unveiling cartilage nanostructures via anisotropic relaxometry of water protons: feasibility or fallacy?”

This Reply addresses the issues raised in the Letter, entitled “Unveiling Cartilage Nanostructures via Anisotropic Relaxometry of Water Protons: Feasibility or Fallacy?” by Y. Pang, K. Momot, and V. Mlynárik (Magnetic Resonance Imaging, 123, 2025, 110508). The authors of the previous letter claimed that our model and theoretical results presented in our paper “Depth-dependent characterization of cartilage nanostructures using MRI signal decays” (Magnetic Resonance Imaging, 120, 2025, 110395) are incorrect. Here, we demonstrate that our model is based on theoretical and experimental data obtained using various methods, and that our results are consistent with previously published findings. Our developed approach allows analyzing the tissue structure: estimating the volumes of ellipsoidal water-filled nanocavities, their angular distributions, and the variations of these characteristics with depth. The principal difference of the new method from the early published studies is that these characteristics were obtained using a single NMR/MRI signal (echo decay) without a sample rotation.

We believe our results contribute to a better understanding of the complex issues related to MRI signal and tissue nanostructures.