Diagnosis of osteoarthritis: imaging

Abstract

Osteoarthritis (OA) is a chronic, debilitating joint disease characterized by degenerative changes to the bones, cartilage, menisci, ligaments, and synovial tissue. Imaging modalities such as radiography, magnetic resonance imaging (MRI), optical coherence tomography (OCT), and ultrasound (US) permit visualization of these structures and can evaluate disease onset and progression. Radiography is primarily useful for the assessment of bony structures, while OCT is used for evaluation of articular cartilage and US for ligaments and the synovium. MRI permits visualization of all intraarticular structures and pathologies, though US or OCT may be preferential in some circumstances. As OA is a disease of the whole joint, a combination of imaging techniques may be necessary in order to gain the most comprehensive picture of the disease state. This article is part of a Special Issue entitled "Osteoarthritis".

Figure 1

A) Antero-posterior weight bearing radiographs of a patient with joint space narrowing and osteophyte formation consistent with bilateral medial osteoarthritis of the knee. Joint pace narrowing is greater in the right knee (arrow) compare with the left knee. B) A magnified view of the right knee joint. The arrow denotes medial JSN. Osteophyte formation can be seen on the femur and tibia.

Figure 2

Bone marrow edema and bone marrow lesions depicted on the medial femur on a T2-weighted fat suppressed MRI(A) and medial tibial plateau on an intermediate-weighted fat suppressed MRI (B).

Figure 3

Diffusion-weighted imaging in patellar cartilage in vivo using a DESS technique. Figure 3A uses low diffusion-weighting. Figure 3B uses high diffusion-weighting. Both imaging techniques afford high resolution, high signal-to-noise ratios, and the ability to calculate apparent diffusion coefficients. Cartilage (solid arrow) and joint fluid (dashed arrow) are well seen on both images. Images courtesy of Ernesto Staroswiecki.

Figure 4

T2 mapping of articular cartilage in the medial femur of a patient with osteoarthritis at two time points. Mapping software allows visualization of the spatial distribution; notice the increased T2 relaxation times in Figure 4B. The T2 relaxation time is overlaid on the images using a color map, with the scale in milliseconds.

Figure 5

T1rho mapping is a physiologic MRI method that has been shown to be sensitive to proteoglycan (PG) changes in articular cartilage. In osteoarthritis, decreases in PG content correspond with increases in T1rho relaxation times. This figure illustrates T1ρ maps of (A) healthy control knee and (B) lateral side of ACL-injured knee at one year follow-up. Early degeneration of articular cartilage is seen by the increased relaxation time in B. Images courtesy of Li X et al. Radiology 2011;258:505–514.

Figure 6

Sodium maps of articular cartilage in a healthy volunteer (A) and a patient with OA (B) overlaid onto proton images. The increased sodium signal in figure 5A correlates with higher glycosaminoglycan (GAG) concentration. As cartilage degenerates and GAG concentration decreases, sodium signal declines (5B).

Figure 7

Images of the medial and lateral mensici pre-surgery (A) and at two follow-up time points (B,C). The use of delayed gadolinium enhanced MRI of cartilage (dGEMRIC) imaging permits quantitative assessment of cartilage integrity which appears to improve following surgical intervention. Images courtesy of Deborah Burstein, PhD.

Figure 8

Correlation of arthroscopic images (top row), optical coherence tomography (middle row), and T2 mapping (bottom row). Images courtesy of Constance R. Chu, MD.

Figure 9

Imaging of the meniscus using ultra-short echo time (uTE) MRI. Cartilaginous and fibrous components, particularly at the tissue periphery, are unmasked with the use of uTE. Images courtesy of Christine Chung, MD.

Figure 10

A) Sagittal grayscale ultrasound image of the suprapatellar pouch of an osteoarthritic knee joint demonstrates synovial fluid (sf), patella (p), distal femur (df), quadriceps tendon (qt), and synovial villi (v). (Image courtesy of Dr. Helen Keen, The University of Western Australia, Australia.) B) Power Doppler ultrasound image of the lateral recess of an osteoarthritic knee joint demonstrates synovial fluid (sf), distal femur (df), and the vascularity within the region of synovial hypertrophy (s) as demonstrated by the flash of color. (Image courtesy of Dr. Helen Keen, The University of Western Australia, Australia.)

Figure 11

Magnetic resonance imaging of synovitis in the medial (A) and lateral (B) compartments. In both images, synovial pathology is hallmarked by the enhanced signal surrounding Hoffa’s fat pad (arrows).