Objective The purpose of this study was to evaluate meniscal degeneration in healthy subjects and subjects with osteoarthritis (OA) using T1ρ and T2 measurements and to examine the interrelationship between cartilage and meniscus abnormalities. Methods Quantitative assessment of cartilage and meniscus was performed using 3T MRI with a T1ρ and T2 mapping technique in 19 controls and 44 OA patients. A sagittal T2-weighted fast spin echo (FSE) fat-saturated image was acquired for cartilage and meniscal Whole-Organ Magnetic Resonance Imaging Score (WORMS) assessment. Western Ontario and McMaster University (WOMAC) scores were obtained to assess clinical symptoms. Results The posterior horn of the medial meniscus (PHMED) had the highest incidence of degeneration. Stratifying subjects on the basis of PHMED grade revealed that the T1ρ and the T2 measurements of the PHMED and the medial tibial (MT) cartilage were higher in subjects having a meniscal tear (meniscal grade 2–4) compared to subjects with a mensical grade of 0 or 1 (p<0.05). While not statistically significant, there was a trend for T1ρ and T2 being higher in PHMED grade 1 compared to grade 0 (p=0.094, p=0.073 respectively). WOMAC scores had a stronger correlation with meniscus relaxation measures than cartilage measures. Conclusions MR T1ρ and T2 measurements provide a noninvasive means of detecting and quantifying the severity of meniscal degeneration. Meniscal damage has been implicated in OA progression and is correlated with cartilage degeneration. Early detection of meniscal damage represented by elevations in meniscal relaxation measures may identify subjects at increased risk for OA.

Purpose-A direct correlation between T 1ρ , T 2 and quantified proteoglycan and collagen contents in human osteoarthritic cartilage has yet to be documented. We aimed to investigate the orientation effect on T 1ρ and T 2 values in human osteoarthritic cartilage; and to quantify the correlation between T 1ρ , T 2 , versus biochemical composition and histology in human osteoarthritic cartilage.Materials and Methods-Thirty-three cartilage specimens were collected from patients who underwent total knee arthroplasty due to severe osteoarthritis, and scanned with a 3T MR scanner for T 1ρ and T 2 quantification. Nine specimens were scanned at three different orientations with respect to the B 0 : 0°, 90°, and 54.7°. Core punches were taken after MRI. Collagen and proteoglycan contents were quantified using biochemical assays. Histology sections were graded using Mankin scores. The correlation between imaging parameters, biochemical contents and histological scores were studied.Results-Both mean T 1ρ and T 2 at 54.7° were significantly higher than those measured at 90°a nd 0°, with T 1ρ showing a less increase compared to T 2 . R 1ρ (1/T 1ρ ) values had a significant, but moderate correlation with proteoglycan contents (R = 0.45, P = 0.002), while R 2 (1/T 2 ) was not correlated with proteoglycan. No significant correlation was found between relaxation times (T 1ρ or T 2 ) and collagen contents. The T 1ρ values of specimen sections with high Mankin scores were significantly higher than those with low Mankin scores (P < 0.05) © 2010 Elsevier Inc. All rights reserved.Corresponding author: Xiaojuan Li, PhD, Department of Radiology and Biomedical Imaging, University of California, San Francisco, 185 Berry Street, Suite 350, San Francisco, CA 94107, xiaojuan.li@radiology.ucsf.edu,. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Competing InterestThe authors declare that they have no competing interests. Conclusions-Quantitative MRI has a great potential to provide non-invasive imaging biomarkers for cartilage degeneration in OA. NIH Public Access

At this early stage of OA, an overall decrease in bone structure parameters and an increase in cartilage parameters (T1rho, T2) were noticed in patients. Trabecular bone structure correlated with articular cartilage parameters suggesting that loss of mineralized bone is associated with cartilage degeneration.

Purpose To quantitate bone marrow edema-like lesions (BMEL) and the radiologic properties of cartilage in knees with acute anterior cruciate ligament (ACL) injuries using T1ρ MRI over a 1 year time period. Methods 9 patients with ACL injuries were studied. MRI were acquired within 8 weeks of the injury, after which ACL reconstruction surgery was performed. Images were then acquired 0.5, 6, and 12 months following reconstructions. The volume and signal intensity of BMEL were quantified at baseline and follow up exams. T1ρ values were quantified in cartilage overlying the BMEL (OC) and compared to surrounding cartilage (SC) at all time-points. Results BMEL were most commonly found in the lateral tibia and lateral femoral condyle. Nearly 50% of BMEL resolved over 1-year. The T1ρ values of the OC in the lateral tibia, medial tibia, and medial femoral condyle were elevated compared to respective regions in SC at all time points, significant only in the lateral tibia (P < 0.05). The opposite results were found in the lateral femoral condyle. For the medial tibia and medial femoral condyle, none of the time periods were significantly different. The percent increase in T1ρ values of OC in the lateral tibia was significantly correlated to BMEL-volume (r = 0.74, P < 0.05). At 1-year, the OC in the lateral tibia, medial tibia, and medial femoral condyle showed increased T1ρ values despite improvement of BMEL. Conclusions In patients following ACL tear and reconstruction, (1) the cartilage overlying BMEL in the lateral tibia experiences persistent T1ρ signal change immediately after acute injuries and at 1-year follow up despite BMEL improvement. (2) The superficial layers of the overlying cartilage demonstrate greater matrix damage than the deep layers, and (3) the volume of the BMEL may predict the severity of the overlying matrix's damage in the lateral tibia. T1ρ is capable of quantitatively and noninvasively monitoring this damage and detecting early cartilage changes in the lateral tibia over time. Level of Evidence IV

Purpose:To quantitatively assess bone marrow edema-like lesion (BMEL) and the overlying cartilage in osteoarthritis (OA) or anterior cruciate ligament (ACL)-injured knees using magnetic resonance imaging (MRI) and spectroscopic imaging (MRSI). Materials and Methods:Eight healthy controls and 30 patients with OA and other injuries who showed BMEL were scanned at 3.0T. A regression model was constructed to automatically calculate the volume of BMEL. Normalized T 1 z-scores were calculated within BMEL-overlying cartilage. Three-dimensional (3D) MRSI was acquired in the BMEL and surrounding bone marrow. Results:The mean T 1 z-score was significantly higher in BMEL-overlying cartilage than that in surrounding cartilage in the lateral tibia of patients with ACL tears (P Ͻ 0.001). Significantly elevated water and unsaturated lipids, and decreased saturated lipids were observed in BMEL. The volume of elevated water correlated with the volume of BMEL. Water content was significantly higher within BMEL than that outside BMEL. The unsaturation index outside BMEL was significantly higher in patients with ACL tears than that in OA.Conclusion: 3D MRSI and T 1 mapping provide tools to quantitatively evaluate BMEL in OA and knee injury. This may allow us to better understand pathophysiology and evolution of injuries and degenerative conditions of the knee.

Summary Objective The aim of this study was to assess the reproducibility of meniscus T1ρ measurements, and to study T1ρ relaxation time in the lateral meniscus (LM) and its relationship with adjacent cartilage T1ρ in knees with acute anterior cruciate ligament (ACL) injuries at 3 T magnetic resonance imaging. Method Quantitative assessment of the meniscus and cartilage was performed in 15 healthy controls and 16 ACL-injured patients using a T1ρ mapping technique. All ACL-injured patients were imaged prior to surgery within 1–3 months of injury. The anterior and posterior horns of LM and medial meniscus (MM) were associated with partitioned weight-bearing cartilage sub-compartments (anterior, central, and posterior). Results T1ρ measurements in the meniscus showed excellent reproducibility (coefficient of variation (CV) < 5%). Significantly elevated T1ρ values were found in the LM in patients compared with controls (P < 0.01). No differences were found in the MM. Significantly higher T1ρ values were found at the posterior horn compared with the anterior horn of patients’ meniscus (P = 0.005). At the posterior sub-compartment of lateral tibia (LT), significantly increased cartilage T1ρ values were found in patients compared with controls (P = 0.002). A significant correlation (R2 = 0.47, P = 0.007) was found between T1ρ values of posterior horn of LM and T1ρ values of posterior sub-compartment of LT cartilage in patients. Conclusion A strong injury-related relationship was demonstrated between meniscus and cartilage biochemical changes. T1ρ mapping techniques provide tools to quantitatively evaluate meniscus and cartilage matrix in patients with ACL injuries.

Objective-The aims of this study were to evaluate the spatial distribution of cartilage structure in controls and patients, and to quantitatively assess the cartilage overlying bone marrow edema-like lesion (BMEL) and within defined cartilage compartments in knees with anterior cruciate ligament (ACL) tears using T1ρ mapping technique at 3 T magnetic resonance imaging.Materials and Methods-The knee joints of 15 healthy controls (4 women, 11 men, mean age = 30.1 year) and 16 patients with ACL tear (5 women, 11 men, mean age = 32.5 years) who showed BMEL was studied using a 3 T GEMR scanner and a quadrature knee coil. The imaging protocol included sequences for cartilage morphology and 3D quantitative T1ρ mapping. Lateral femoral condyle and medial femoral condyles compartments were partitioned into anterior and posterior nonweight-bearing (ant-nwb and postnwb) portions and weight-bearing (wb) portions in all subjects. In patients only, cartilage overlying BMEL and surrounding cartilage portions were also defined. T1ρ values were quantified in cartilage overlying BMEL and surrounding compartments and in each defined compartment of the ACL-injured knees, and compared with controls.Results-Significantly elevated T1ρ values were found in the femoral nonweight-bearing (nwb) portions when compared with weight-bearing (wb) portions both in patients and controls. Significantly increased T1ρ values were found in cartilage overlying BMEL when compared with surrounding cartilage at the lateral tibia (LT), but no difference was found in the lateral femoral condyle. Conclusion-T1ρmapping technique provides tools to quantitatively evaluate the cartilage matrix overlying BMEL in patients with ACL injuries. Cartilage abnormalities are already present following initial ACL injuries over the lateral tibia. Quantitative MRI can allow critical evaluation of medical and surgical treatments for ligament and degenerative conditions of the knee. The anterior cruciate ligament (ACL) is the most commonly torn ligament in the knee, with more than 80,000 injuries occurring annually in the United States alone. 1 The rupture of the ACL frequently occurs in young active individuals. The injury is usually a result of a valgus and internal rotational torque to the knee. During the injury, the knee can sublux after ACL rupture and the lateral femoral condyle (LFC) can impact the posterior aspect of the lateral tibia, resulting in the classic bone marrow edema-like lesions (BMELs) or osteochondral lesions within the lateral compartment, also known as the "kissing lesions."2 KeywordsThe prevalence of BMEL in patients with ACL injuries has been reported to be up to 70% to 80%. 3,4 The BMEL is usually located in the middle portion of the lateral femoral condyle and the posterior portion of the lateral tibial plateau. Despite the high prevalence of these BMEL with ACL ruptures, little is known about the clinical consequences of these findings or about their relationship with local and global cartilage degeneration.Magnetic resonance imaging (M...

3D MRI (7T) enables in vivo monitoring of compartmental changes in OA-related femorotibial rat cartilage thickness vs contralateral age-matched knees.