Computed Tomography-Mediated Registration of Trapeziometacarpal Articular Cartilage Using Intraarticular Optical Coherence Tomography and Cryomicrotome Imaging: A Cadaver Study

Abstract

Objective: Accurate, high-resolution imaging of articular cartilage thickness is an important clinical challenge in patients with osteoarthritis, especially in small joints. In this study, computed tomography (CT) mediated catheter-based optical coherence tomography (OCT) was utilized to create a digital reconstruction of the articular surface of the trapeziometacarpal (TMC) joint and to assess cartilage thickness in comparison to cryomicrotome data.

Design: Using needle-based introduction of the OCT probe, the articular surface of the TMC joint of 5 cadaver wrists was scanned in different probe positions with matching CT scans to record the intraarticular probe trajectory. Subsequently and based on the acquired CT data, 3-dimensional realignment of the OCT data to the curved intraarticular trajectory was performed for all probe positions. The scanned TMC joints were processed using a cryomicrotome imaging system. Finally, cartilage thickness measurements between OCT and cryomicrotome data were compared.

Results: Successful visualization of TMC articular cartilage was performed using OCT. The CT-mediated registration yielded a digital reconstruction of the articular surface on which thickness measurements could be performed. A near-perfect agreement between OCT and cryomicrotome thickness measurements was found (r² = 0.989).

Conclusion: The proposed approach enables 3D reconstruction of the TMC articular surface with subsequent accurate cartilage thickness measurements, encouraging the development of intraarticular cartilage OCT for future (clinical) application.

Keywords: articular cartilage; co-registration; computed tomography; imaging cryomicrotome; optical coherence tomography.

Figure 1.

(A) CT data of the trapeziometacarpal joint with intraarticular OCT probe, showing the trapezium (Trap) and first metacarpal bone (MC1). The white arrow signifies the OCT probe as seen on a single CT slice. (B) CT data after separate segmentation of Trap, MC1, and probe (purple) based on CT Hounsfield values. The white scale bar represents 5.0 mm.

Figure 2.

(A) Segmented trapezium, first metacarpal, and OCT probe from CT data with overlay of an OCT dataset volume reconstruction before 3D deformation. (B) Co-registration of CT and OCT after 3D deformation. The OCT data are refitted to the segmented probe trajectory. The black scale bar represents 5.0 mm.

Figure 3.

Inferior view. Overlay of segmented CT data for 3 different intraarticular probe positions (red, blue, purple) with matching, 3D realigned, volume-reconstructed OCT datasets. In this way, a digital reconstruction of the trapeziometacarpal articular surfaces is created. The black scale bar represents 5.0 mm.

Figure 4.

Cryomicrotome TMC cartilage data visualization. The trapezium and first metacarpal are clearly identified. A distinct layer of cartilage can be seen on the articular surface of the trapezium (white arrows). Example of 3D cartilage segmentation is shown in yellow. The white scale bar represents 5.0 mm.

Figure 5.

Overlay of segmented CT bone structures (Trap and MC1) and cryomicrotome-derived cartilage thickness data with color map (range: red 0.1 → blue 1.1 mm).

Figure 6.

Flowchart schematically depicting the various data post-processing and visualization steps.

Figure 7.

Cross-sectional OCT image with overlay of MC1 cryomicrotome cartilage data (yellow/silver) for thickness comparison (white arrows). Note the indentation the OCT probe makes into the soft cartilage layer. The white scale bar represents 2.0 mm.

Figure 8.

Linear regression analysis of cartilage thickness measurements (n = 150), comparing OCT to cryomicrotome cartilage data.