The new frontier of MRI: virtual dissection with 3D-PDw sequence. A pilot study on ATiFL anatomy

There is much conflicting data regarding the anatomy of the anterior tibiofibular ligament (ATiFL), even in studies with anatomical specimens. Therefore, this study aims to reassess the anatomy of this ligament using a high-resolution isotropic 3D-PDw MRI sequence.

From February to May 2024, 72 MRI scans (3 T) of the ankle were performed at Amsterdam UMC. The inclusion criterion was patients over 16 years of age. The exclusion criteria were absence of a 3D-PDw scan or positive history of ATiFL trauma or surgery, congenital anomalies, metallic or movement artifacts. The 43 3D-PDw valid scans, allowed for aligning the planes along the individual fascicles of the ligament.

A total of 43 scans allowed for adequate ligament assessment. The high spatial resolution (0,23 mm) of 3DPDw allowed the identification of three fascicles: superficial, deep, and distal. Regarding dimensions the superficial is the thickest and widest (mean 2.68 x 9.28 mm) and the distal the longest (mean 15.45 mm). Regarding orientation (para-sagittal plane from the fibula to the tibia) the superficial and distal fascicle have a transverse orientation, while the deep fascicle is oriented backward. Regarding the shape, they are fanned in 97.7 %, 71.7 %, and 25.6 % respectively, while they are band-like in the remaining cases. We did not identify any anatomical variance regarding the number of fascicles.

The use of volumetric isotropic sequences as the 3D-PDw, can be a very useful tool for the anatomical study of ligamentous structures in the absence of available anatomical specimens. Understanding the exact anatomy of this structure is crucial for managing both acute and chronic traumatic pathology.