Three-dimensional computerized reconstruction. Illustration of incremental articular cartilage thinning
P J Tebben1, T W Pope, G Hinson
1Imaging Resource Center, Kansas University School of Medicine, Kansas City 66103, USA.
Rationale And Objectives:
The authors have addressed the ability of magnetic resonance (MR) imaging to resolve incremental thinning of articular cartilage by assessment of three-dimensional (3-D) and two-dimensional (2-D) representations.
Methods:
Using a porcine knee model, sequential cartilage shavings were characterized using a 3-D fat suppressed spoiled gradient-echo (SPGR) MR imaging protocol that provided good contrast between high-signal articular cartilage and lower signal surrounding tissues. Lesion dimensional measurements were made on both MR images and 3-D computerized reconstructions. Volumes of cartilage removed were approximately 0.06 mL.
Results:
Incremental articular cartilage thinning typically was apparent on 3-D reconstructed images. Three-dimensional articular cartilage reconstructions were effective in depicting location and orientation of shaved cartilage regions. Average percent error associated with length and with measurements based on 2-D MR images was approximately 19% for observer 1 and 33% for observer 2 when compared with direct measurements of the shaved cartilage. Average percent error of thickness measurements based on 2-D MR was approximately 21% for observer 1 and 37% for observer 2. Overall average errors associated with length, width, and thickness measurements were approximately 25%.
Conclusions:
Incremental thinning of articular cartilage can be tracked qualitatively and quantitatively using 3-D computerized reconstructions and 2-D MR images. Errors associated with the quantitative measurements can be attributed to limitations of measurement methods and intrinsic limitation of MR resolution.
