4D CT is a promising technique for the detection of alteration in joint kinematics induced by different pathologies [1-2]. The aim of the study was to investigate the
ability of 4D-CT to detect changes of the talocrural and subtalar joint after sequential sectioning of ankle lateral compartment ligaments.
A 256-slice GE Revolution CT Scanner (80kV, 25 mA, gantry rotation time 0.28 s, z-axis coverage 120mm, scanning time 3.92 s) was adapted to perform dynamic
imaging acquisition on a fresh frozen ankle/foot. The tibia was fixed on a custommade device and the ankle joint was moved at a pace of 25 cycles/minute. After
obtaining four dynamic motion acquisitions, the Anterior Talo-Fibular Ligament (first scenario), the Calcaneo-Fibular Ligament (second scenario) and the
Posterior Talo-Fibular Ligament (third scenario) were sequentially cut. Four separate 4D acquisitions were performed for each of the three cut scenarios.
Using mutual information as the similarity metric, the talus and the tibia of the dynamic sequences were rigidly registered to a reference image dataset of the
foot at rest and transformation matrices were derived. The predefined technical frame (XYZ) of the CT scanner was used to describe the 3D-motion. Joint
kinematic of the talocrural joint was described as the displacement of a point located on the centre of the articular surface of the talus, while the movement of
the calcaneus was described as displacement of the centroid.
Maximum detectable differences observed regarding displacement of the talocrural joint were 0.56mm, 0.78mm and 0.21mm between intact vs first cut,
intact vs second cut and intact vs third cut respectively, along the X-axis (mediolateral displacement); 1.54mm, 2.37mm and 2.73mm along the Y-axis (anteriorposterior displacement) and 2.61mm, 2.41mm and 3.85mm along the Z-axis (caudo-cranial displacement) (Figure 1). For the subtalar joint, the differences
between different scenarios were 0.98mm, 0.51mm and 1.63mm along the X-axis, 0.28mm, 0.09mm and 0.38mm along the Y-axis, and 1.05mm, 0.96mm and
1.34mm along the Z-axis. Each acquisition required a radiation dose (CTDIvol) of 1.9mGy.
Except for the X axis where the movement was minimal, the results show clear differences between the four scenarios, especially along the axis perpendicular to
the gantry (Z-axis). This confirms the fact that 4D-CT may be able to detect minimal changes in joint kinematics due to ligaments failure using minimal radiation
exposure for the patient. It also highlights the potential of 4D-CT as a tool to detect musculoskeletal pathologies that occur only during the motion and that are
not detectable at the extremes joint positions or in with static examinations.
1. Mat Jais IS, Tay SC. Clinical radiology. 2017;72(9):794.e1-.e9.
2. Gondim Teixeira et al., AJR Am J Roentgenol. 2017;208(1):150-8.
Originele taal-2English
StatusUnpublished - 2018
EvenementISEK 2018 - XXII Congress of theInternational Society of Electrophysiology and Kinesiology - Dublin
Duur: 30 jun 20182 jul 2018


ConferenceISEK 2018 - XXII Congress of theInternational Society of Electrophysiology and Kinesiology


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