Assessing degeneration of human articular cartilage with ultra-short echo time (UTE) T2* mapping

Abstract

Objective To examine the sensitivity of ultra-short echo time (UTE) T2* mapping to collagen matrix degeneration in human articular cartilage. Methods MRI UTE-T2* maps and standard T2 maps were acquired on four human tibial plateau explants. Thirty-three osteochondral cores were harvested for polarized light microscopy (PLM), and composition analyses. Collagen matrix integrity was evaluated from PLM and histological images. Matrix integrity and composition was compared to standard T2 values and UTE-T2* values on a spatially registered basis. Results UTE-T2* values varied with matrix degeneration (p=0.008) and were lower in severely degraded cartilage compared to healthy tissue (p=0.012). A trend for higher UTE-T2* values in healthy tissue compared to mildly degenerate tissue (p=0.051) was detected. Standard T2 values were not found to vary with matrix degeneration (p=0.13) but tended to be higher in severely degraded cartilage compared to healthy tissue. UTE-T2* value variations were independent of type II collagen and glycosaminoglycan contents. UTE-T2* mapping of deep cartilage, adjacent to subchondral bone, was more robust than standard T2 mapping in this zone. Conclusion UTE-T2* mapping of articular cartilage is sensitive to matrix degeneration and detects short T2 signal, particularly in deep tissue, that is not well captured by standard T2 mapping. Correlation of UTE-T2* values and PLM indices supports the hypothesis that both may be sensitive to collagen microstructure. Further exploration of UTE-T2* mapping as a noninvasive tool to detect early articular cartilage degeneration is warranted.

Quantitative Ultrashort Echo Time Magnetic Resonance Imaging Evaluation of Postoperative Menisci: A Pilot Study

“…Quantitative MRI (qMRI), with its ability to quantify tissue relaxation times, presents an objective measure of collagen organization. Current qMRI techniques such as T2* mapping for articular cartilage cannot capture the very short T2 values of meniscal fibrocartilage [10]. T2* mapping using an ultrashort echo time (UTE) pulse sequence acquires short echo images (echo time (TE) ∼0.3 ms) to produce multi-echo images for quantitative T2* calculation [2].…”

Novel Quantitative Imaging for Early Detection of Joint Tissue Injury to Support Early Treatment Strategies

“…Quantitative strategies for the diagnosis and staging of joint tissue degeneration prior to the breakdown of the articular cartilage or meniscal surfaces remain a challenge. Our research has shown that the current clinical standard, arthroscopic visualization, and palpation of cartilage and menisci, may be insensitive to early subsurface alterations in these tissues, particularly in the deepest layers of articular cartilage [1][2][3]. Our work with quantitative Magnetic Resonance Imaging (MRI) and Optical Coherence Tomography (OCT) reveals a strong potential for these methods to provide information regarding early diagnosis and staging of subsurface tissue injury that are not readily available with current technologies [3][4][5].…”

“…MRI ultra-short TE-enhanced T2* (UTE-T2*) mapping reflects the cartilage collagen matrix integrity as determined by polarized light microscopy and is sensitive to signal from the deepest layers of cartilage adjacent to bone [2,3]. UTE-T2* mapping of articular cartilage and meniscus has the potential to visualize deep tissue characteristics better than standard T2 mapping due to its sensitivity to signal from short T2 tissues.…”

Osteoarthritis: From Palliation to Prevention

“…Recently, ultrashort echo time enhanced T2* (UTE-T2*) mapping was developed to evaluate the subsurface matrix of articular cartilage 10,11 (Fig. 2).…”