Magnetic Resonance Imaging T2 Values Research Articles

Evaluation of Open Versus Arthroscopic Anterior Talofibular Ligament Reconstruction for Chronic Lateral Ankle Instability With Talar and Subtalar Cartilage MRI T2 Mapping: A 3-Year Prospective Study.

Previous studies have examined patients with chronic lateral ankle instability (CLAI) undergoing open and arthroscopic anterior talofibular ligament (ATFL) reconstruction, reporting equivalent clinical results between the 2 procedures. However, data on the magnetic resonance imaging (MRI) outcomes on cartilage health after the 2 procedures are limited. To compare the cartilage MRI T2 values of the talar and subtalar joints between patients with CLAI undergoing open and arthroscopic ATFL reconstruction. Cohort study; Level of evidence, 3. A prospective study was conducted on patients who underwent open or arthroscopic ATFL reconstruction between January 2018 and December 2019, with a mean follow-up duration of 3 years. MRI scans and American Orthopaedic Foot & Ankle Society (AOFAS) and Tegner score estimations were completed by patients ≤1 week before surgery, as a baseline measurement, and at a 3-year follow-up. A total of 21 healthy volunteers were included who underwent MRI at baseline. Cartilage health was evaluated using MRI T2 mapping. The talar and subtalar cartilage regions were segmented into 14 subregions. At baseline, patients with CLAI had substantially higher T2 values in the medial anterior, medial center, medial posterior, and lateral center regions on the talus compared with the healthy controls (P = .009, .003, .001, and .025, respectively). Remarkable increases in T2 values in the lateral posterior region on the talus were observed from baseline to follow-up in the open group (P = .007). Furthermore, T2 values were considerably higher in the medial center, medial posterior, lateral posterior, and lateral posterior calcaneal facets of the posterior subtalar joint at follow-up in the arthroscopic group compared with the baseline values (P = .025, .002, .006, and .044, respectively). No obvious differences in ΔT2 values were noted between the 2 groups at follow-up. The AOFAS and Tegner scores remarkably improved from baseline to follow-up for the 2 groups (open: 3.25 ± 0.58 vs 5.13 ± 0.81, P < .001; arthroscopic: 3.11 ± 0.90 vs 5.11 ± 1.08, P < .001), with no considerable difference between them. The elevated T2 values of cartilage could not be fully recovered after open or arthroscopic ATFL reconstruction. Both arthroscopic and open ATFL reconstruction displayed similar effects on cartilage health concerning ΔT2, but the arthroscopic group demonstrated more degenerative cartilage subregions than the open group.

Evaluation of intervertebral disc degeneration using T2 signal ratio on magnetic resonance imaging

PurposeIntervertebral disc degeneration is assessed clinically by magnetic resonance imaging (MRI). Although some quantitative evaluation methods for MRI under special imaging conditions have been reported, they are widely and generally difficult to use. The aim of this study is to determine if intervertebral disc degeneration can be assessed using the ratio of MRI T2 values of the disc to the spinal cord T2 values. MethodsSignal ratio was calculated using the T2 signal intensity of the disc and the spinal cord on MRI under common conditions for a new assessment of disc degeneration. T2-weighted images of 100 patients undergoing MRI twice within a year under different imaging conditions, 1.5 T or less and 3.0 T, were used for the assessment. The T2 signal intensity was measured at the center of the discs at L2-3, L3-4, L4-5, L5-S1 and the spinal cord at T12 level. Signal ratio was calculated using these T2 signal intensity values. The ratio of the difference between the first and second values to the mean of the first and second values was calculated to confirm the equivalence of MRI assessments of disc degeneration in the same patient under different imaging conditions. ResultsThe equivalence of values between the first MRI and the second MRI in the signal ratio was significantly higher than that in the T2 signal intensity. In addition, the signal ratio was negatively correlated with age and were significantly associated with Pfirrmann grade. ConclusionsBy using the signal ratio, disc degeneration can be evaluated by MRI even under different imaging conditions.

Intradiscal injection of monosodium iodoacetate induces intervertebral disc degeneration in an experimental rabbit model

BackgroundEstablishing an optimal animal model for intervertebral disc (IVD) degeneration is essential for developing new IVD therapies. The intra-articular injection of monosodium iodoacetate (MIA), which is commonly used in animal models of osteoarthritis, induces cartilage degeneration and progressive arthritis in a dose- and time-dependent manner. The purpose of this study was to determine the effect of MIA injections into rabbit IVDs on the progression of IVD degeneration evaluated by radiographic, micro-computerized tomography (micro-CT), magnetic resonance imaging (MRI), and histological analyses.MethodsIn total, 24 New Zealand White (NZW) rabbits were used in this study. Under general anesthesia, lumbar discs from L1–L2 to L4–L5 had a posterolateral percutaneous injection of MIA in contrast agent (CA) (L1–L2: CA only; L2–L3: MIA 0.01 mg; L3–L4: 0.1 mg; L4–L5: 1.0 mg; L5–L6: non-injection (NI) control). Disc height was radiographically monitored biweekly until 12 weeks after injection. Six rabbits were sacrificed at 2, 4, 8, and 12 weeks post-injection and processed for micro-CT, MRI (T2-mapping), and histological analyses. Three-dimensional (3D) disc height in five anatomical zones was evaluated by 3D reconstruction of micro-CT data.ResultsDisc height of MIA-injected discs (L2–L3 to L4–L5) gradually decreased time-dependently (P < 0.0001). The disc height of MIA 0.01 mg-injected discs was significantly higher than those of MIA 0.1 and 1.0 mg-injected discs (P < 0.01, respectively). 3D micro-CT analysis showed the dose- and time-dependent decrease of 3D disc height of MIA-injected discs predominantly in the posterior annulus fibrosus (AF) zone. MRI T2 values of MIA 0.1 and 1.0 mg-injected discs were significantly decreased compared to those of CA and/or NI controls (P < 0.05). Histological analyses showed progressive time- and dose-degenerative changes in the discs injected with MIA (P < 0.01). MIA induced cell death in the rabbit nucleus pulposus with a high percentage, while the percentage of cell clones was low.ConclusionsThe results of this study showed, for the first time, that the intradiscal injection of MIA induced degenerative changes of rabbit IVDs in a time- and dose-dependent manner. This study suggests that MIA injection into rabbit IVDs could be used as an animal model of IVD degeneration for developing future treatments.

Quantitative MRI in myositis patients: comparison with healthy volunteers and radiological visual assessment

To assess whether magnetic resonance imaging (MRI)-based measurements of T2, fat fraction, diffusion tensor imaging, and muscle volume can detect differences between the muscles of myositis patients and healthy controls, and to identify how they compare with semi-quantitative MRI diagnosis. Sixteen myositis patients and 16 age- and gender-matched healthy controls underwent MRI of their thigh. Quantitative MRI measurements and radiologists' semi-quantitative scores were assessed. Strength was assessed using an isokinetic dynamometer. Fat fraction and T2 values were higher in myositis patients whereas muscle volume was lower compared to healthy controls. There was no difference in diffusion. Muscle strength was lower in myositis patients compared to healthy controls. In a subgroup of eight patients, scored as unaffected by radiologists, T2 values were still significantly higher in myositis patients. Quantitative MRI measurements can detect differences between myositis patients and healthy controls. Changes in the muscles of myositis patients, undetected by visual, semi-quantitative scoring, can be detected using quantitative T2 measurements. This suggests that MRI T2 values may be useful for the management of myositis patients.

Effect of diminished flow in rabbit lumbar arteries on intervertebral disc matrix changes using MRI T2-mapping and histology

BackgroundImpaired lumbar artery flow has been reported in clinical and epidemiological studies to be associated with low back pain and lumbar disc degeneration. However, it has not been experimentally demonstrated that impaired lumbar artery flow directly induces intervertebral disc (IVD) degeneration by affecting IVD matrix metabolism. The purpose of this study was to evaluate whether ligation of the lumbar artery can affect degenerative changes in the rabbit IVD.MethodsNew Zealand White rabbits (n = 20) were used in this study. Under general anesthesia, the third and fourth lumbar arteries were double-ligated using vascular clips. The blood flow to the L3/L4 disc (cranial disc) was reduced by ligation of the third lumbar artery and that of the L5/L6 disc (caudal disc) by ligation of the fourth lumbar artery. The blood flow to the L4/L5 disc (bilateral disc) was decreased by ligation of both the third and fourth lumbar arteries. The L2/L3 disc was used as the control. Disc height was radiographically monitored biweekly until 12 weeks after surgery. The rabbits were sacrificed at 4, 8, and 12 weeks after surgery and magnetic resonance imaging (MRI) T2-mapping, histology and immunohistochemistry were assessed.ResultsLumbar artery ligation did not induce significant changes in disc height between control and ischemic discs (cranial, bilateral and caudal discs) during the 12-week experimental period. T2-values of ischemic discs had no significant trend to be lower than those of the control L2/L3 discs. Histologically, Safranin-O staining changed following ligation of corresponding IVD lumbar arteries. Histological grading scores for disc degeneration, which correlated significantly with MRI T2-values, had significant changes after the surgery. Immunohistochemical analysis showed that the ligation of lumbar arteries significantly affected a change in the percentage of HIF-1α immunoreactive cells of ischemia discs compared to that of control discs four weeks after the surgery (p < 0.05).ConclusionsThe MRI and histology results suggest that diminished flow in lumbar arteries induce mild changes in the extracellular matrix metabolism of rabbit IVDs. These matrix changes, however, were not progressive and differed from the degenerative disc changes seen in the process of human IVD degeneration.

Effects Of Downhill Running On Muscle MRI T2 In Young mdx Mice

Previous studies have demonstrated that downhill treadmill running causes skeletal muscle damage that can be detected with magnetic resonance transverse relaxation time (T2) in adult dystrophic mice (mdx). However, young mdx mice (under 12 weeks of age) are characterized by a peak inflammatory phase with greater heterogeneity among muscles, potentially making it more difficult to detect T2 changes. PURPOSE: To determine whether muscle damage following downhill running can be detected in young mdx mice using proton magnetic resonance imaging (MRI) and spectroscopy (MRS). METHODS: C57BL/10ScSn-DMDmdx (mdx, n=5) and wild-type C57BL/10ScSn (controls, n=5) male mice of 6-9 weeks of age performed downhill running on a treadmill (14% grade at 8-12m/min for 45-60 min). MRI/MRS was conducted prior to and 24 hours following running in the mice hindlimbs. T2-weighted, multiple-slice, single spin-echo MR axial images were acquired (TR 2s, TE 14/40 ms, 12 slices) from the hindlimbs. MRI T2 values were calculated on a pixel-by-pixel basis for the anterior compartment (AC), posterior compartment (PC), and the deep medial region between the tibia and fibula (MC). In addition, single voxel 1H-MRS data were acquired from the soleus and gastrocnemius using stimulated echo acquisition mode (STEAM; TR 9 s, 32 TE’s exponentially spaced: 5-288 ms, 4 phase cycles) with a 4.7 T Varian/Agilent MR system. RESULTS: At baseline, T2 was elevated (p<0.05) in mdx mice (26.8±1.2ms) compared to controls (24.8±0.9 ms). Following downhill running, the mdx mice had elevated (p<0.05) T2 values compared to baseline when a composite of the compartments were compared (Pre: 26.8±1.2ms; Post: 28.8±1.4 ms). The MC was typically (80%) the most affected hindlimb region in the mdx mice. Similarly, 1H-MRS derived T2 values were increased (p=0.05) in a composite measure of the soleus and gastrocnemius after downhill running (29.8±4.2ms) in mdx compared to before downhill running (26.4±2.8ms). There were no significant changes in T2 in control mice after performing the downhill running protocol. CONCLUSIONS: Overall, our findings support the use of downhill running combined with MR T2 measures as a valuable approach for testing potential therapeutic interventions in young dystrophic mice. Funding Source: NIH (NIAMS) R01 AR070101.

Magnetic resonance imaging T1 and T2 mapping provide complementary information on the bone mineral density regarding cancellous bone strength in the femoral head of postmenopausal women with osteoarthritis

BackgroundSince bone mass is not the only determinant of bone strength, there has been increasing interest in incorporating the bone quality into fracture risk assessments. We aimed to examine whether the magnetic resonance imaging (MRI) T1 or T2 mapping value could provide information that is complementary to bone mineral density for more accurate prediction of cancellous bone strength. MethodsFour postmenopausal women with hip osteoarthritis underwent 3.0-T MRI to acquire the T1 and T2 values of the cancellous bone of the femoral head before total hip arthroplasty. After the surgery, the excised femoral head was portioned into multiple cubic cancellous bone specimens with side of 5 mm, and the specimens were then subjected to microcomputed tomography followed by biomechanical testing. FindingsThe T1 value positively correlated with the yield stress (σy) and collapsed stress (σc). The T2 value did not correlate with the yield stress, but it correlated with the collapsed stress and strength reduction ratio (σc/σy), which reflects the progressive re-fracture risk. Partial correlation coefficient analyses, after adjusting for the bone mineral density, showed a statistically significant correlation between T1 value and yield stress. The use of multiple coefficients of determination by least squares analysis emphasizes the superiority of combining the bone mineral density and the MRI mapping values in predicting the cancellous bone strength compared with the bone mineral density-based prediction alone. InterpretationThe MRI T1 and T2 values predict cancellous bone strength including the change in bone quality.

Regional Collagen Fiber Network in the Articular Disc of the Human Temporomandibular Joint: Biochemical 3-Tesla Quantitative Magnetic Resonance Imaging Compared to Quantitative Histologic Analysis of Fiber Arrangement.

To evaluate the regional collagen fiber network in the human temporomandibular joint (TMJ) disc by using biochemical magnetic resonance imaging (MRI) and quantitative histology. MRI of 5 heads (10 TMJ discs) obtained from partially dentate or edentulous cadavers was performed at 3-Tesla MRI by using a flexible, 8-channel transmit-receive coil. After MRI, all 10 discs were processed histologically. Percentages of coronal, sagittal, and transverse collagen fibers were assessed stereologically for the anterior, central, and posterior parts of the disc. An anisotropy index was calculated for collagen fiber arrangement in all three regions of interest. In the central part of the TMJ disc, collagen fibers were arranged anisotropically with a preferentially sagittal direction. In the anterior and posterior parts, evidence for fibers being arranged isotropically (randomly) without preferred direction was found. Mean MRI T2 values appeared to be correlated with the anisotropy index of collagen fibers (r = -0.45; P < .05). When tested individually, T2 values of the isotropic anterior and posterior disc regions showed a partial but significant correlation with the anisotropy index of collagen fibers (r = -0.54; P < .05), whereas the anisotropic central part did not (P > .05). This study has provided the first systematic comparison of quantitative data on collagen fiber isotropy and anisotropy assessed in histologic sections with biochemical quantitative MRI for human TMJ fibrous cartilage.

Magnetic Resonance Imaging T2 Values of Stifle Articular Cartilage in Normal Beagles.

The purpose of this study was to evaluate regional differences of canine stifle articular cartilage using the quantitative magnetic resonance imaging (MRI) technique of T2 mapping. Fourteen stifle joints from seven juvenile male Beagle dogs with no evidence or prior history of pelvic limb lameness were imaged ex vivo using standard of care fast spin echo MRI and quantitative T2 mapping protocols. Regions of interest were compared between the femoral, patellar and tibial cartilages, as well as between the lateral and medial femorotibial compartments. Limbs were processed for histology with standard stains to confirm normal cartilage. The average T2 value of femoral trochlear cartilage (37.5 ± 2.3 ms) was significantly prolonged (p < 0.0001) as compared with the femoral condylar, patellar and tibial condylar cartilages (33.1 ± 1.5 ms, 32.8 ± 2.3 ms, and 28.0 ± 1.7 ms, respectively). When comparing medial and lateral condylar compartments, the lateral femoral condylar cartilage had the longest T2 values (34.8 ± 2.8 ms), as compared with the medial femoral condylar cartilage (30.9 ± 1.9 ms) and lateral tibial cartilage (29.1 ± 2.3 ms), while the medial tibial cartilage had the shortest T2 values (26.7 ± 2.4 ms). As seen in other species, regional differences in T2 values of the canine stifle joint are identified. Understanding normal regions of anticipated prolongation in different joint compartments is needed when using quantitative imaging in models of canine osteoarthritis.

Effect of iron overload on impaired fertility in male patients with transfusion-dependent beta-thalassemia.

BackgroundTo investigate the fertility of male patients with transfusion-dependent beta-thalassemia, and to use magnetic resonance imaging (MRI) as a novel method to assess the iron overload status of testis in such patients.MethodsTwenty-one male patients with transfusion-dependent beta-thalassemia and five normal male controls enrolled in this study. Hormonal profiles, iron levels, MRI testicular dimension, MRI T2 values, parameters for sperm quality, and sperm DNA fragmentation (SDF) of participants were measured.ResultsThe MRI T2 values of the testis were significantly lower in transfusion-dependent beta-thalassemia patients than in normal controls (P=0.027), and they correlated to serum ferritin levels in all enrolled subjects (R2=0.258, P=0.008). There were significantly lower sperm concentrations (P=0.037), a lower percentage of sperm with normal morphology (P=0.001), and a higher percentage of SDF (P=0.009) in transfusion-dependent beta-thalassemia patients without hypogonadotropic hypogonadism and with spontaneous spermatogenesis compared with normal controls. The percentage of SDF was significantly correlated with serum ferritin levels in transfusion-dependent beta-thalassemia male patients with spontaneous spermatogenesis (R2=0.48, P=0.009).ConclusionOur study is the first demonstration of iron deposition in the testis of patients with transfusion-dependent beta-thalassemia based on imaging, and such findings might explain the high prevalence of impaired fertility in above patients with normal pituitary function.

Dose-response of superparamagnetic iron oxide labeling on mesenchymal stem cells chondrogenic differentiation: a multi-scale in vitro study.

AimThe aim of this work was the development of successful cell therapy techniques for cartilage engineering. This will depend on the ability to monitor non-invasively transplanted cells, especially mesenchymal stem cells (MSCs) that are promising candidates to regenerate damaged tissues.MethodsMSCs were labeled with superparamagnetic iron oxide particles (SPIO). We examined the effects of long-term labeling, possible toxicological consequences and the possible influence of progressive concentrations of SPIO on chondrogenic differentiation capacity.ResultsNo influence of various SPIO concentrations was noted on human bone marow MSC viability or proliferation. We demonstrated long-term (4 weeks) in vitro retention of SPIO by human bone marrow MSCs seeded in collagenic sponges under TGF-β1 chondrogenic conditions, detectable by Magnetic Resonance Imaging (MRI) and histology. Chondrogenic differentiation was demonstrated by molecular and histological analysis of labeled and unlabeled cells. Chondrogenic gene expression (COL2A2, ACAN, SOX9, COL10, COMP) was significantly altered in a dose-dependent manner in labeled cells, as were GAG and type II collagen staining. As expected, SPIO induced a dramatic decrease of MRI T2 values of sponges at 7T and 3T, even at low concentrations.ConclusionsThis study clearly demonstrates (1) long-term in vitro MSC traceability using SPIO and MRI and (2) a deleterious dose-dependence of SPIO on TGF-β1 driven chondrogenesis in collagen sponges. Low concentrations (12.5–25 µg Fe/mL) seem the best compromise to optimize both chondrogenesis and MRI labeling.

2-deoxy-D-glucose modified supermagnetic iron oxide nanoparticles enhance the contrasting effect on MRI of human lung adenocarcinoma A549 tumor in nude mice

To evaluate the role of 2-deoxy-D-glucose (2-DG) modified supermagnetic iron oxide nanoparticles (SPIO) (γ-Fe2O3@DMSA-DG NPs) in tumor detection as a magnetic resonance imaging (MRI) contrast agent. γ-Fe2O3@DMSA-DG NPs was prepared. The degree of A549 cells targeted absorption of γ-Fe2O3@DMSA-DG NPs was detected by Prussian blue staining, colorimetric assay, T2W and multi-echo sequence MRI. γ-Fe2O3@DMSA NPs was used as a control agent, and free D-glucose as a competitive inhibitor. Human lung adenocarcinoma A549 xenograft tumor was prepared in nude mice. Sterile aqueous suspension of γ-Fe2O3@DMSA NPs or γ-Fe2O3@DMSA-DG NPs was injected into the tail vein of nude mice. Before and 6, 12, 24, 48 h after injection, MRI imaging of the mice was performed. T2 signal intensity of the tumor, brain, liver and thigh skeletal muscles, and T2 values of the tumors were measured. The average diameter of the particles was about 10 nm, and there were no significant differences between the diameters of γ-Fe2O3@DMSA NPs and γ- Fe2O3@DMSA-DG NPs. The IR spectra showed the C-N retractable vibration peak at γ-Fe2O3@DMSA-DG NPs surface, indicating that 2-DG was conjugated to the γ-Fe2O3@DMSA NPs. The Prussian blue staining, colorimetric assay, MRI T2 signal intensity and T2 values revealed that γ-Fe2O3@DMSA-DG NPs were significantly more absorbed by A549 cells at growth peak than γ-Fe2O3@DMSA NPs, and the absorption of γ-Fe2O3@DMSA-DG NP was inhibited by free D-glucose. The results of in vivo examination showed that before and at 6, 12, 24, 48 h after injection of γ-Fe2O3@DMSA-DG NPs, the mean T2 signal intensities of the tumors were (326.00 ± 16.26)s, (276.40 ± 5.13)s, (268.40 ± 30.58)s, (240.40 ± 25.93)s, (262.20 ± 30.04)s, respectively, and the T2 values of the tumors were (735.80 ± 20.93) ms, (645.80 ± 69.58) ms, (615.00 ± 124.61) ms, (570.60 ± 67.78) ms, and (537.80 ± 105.29) ms, respectively. However, before and at 6, 12, 24, 48 h after injection of γ-Fe2O3@DMSA NPs, the mean T2 signal intensities of the tumors were (335.60 ± 4.93)s, (290.80 ± 5.93)s, (273.40 ± 15.08)s, (327.40 ± 16.65)s, and (313.20 ± 20.45)s, respectively, and T2 values were (686.00 ± 21.44)ms, (617.80 ± 69.93)ms, (645.20 ± 85.89)ms, (669.40 ± 13.72)ms, and (608.80 ± 61.90)ms, respectively. The T2 signal intensity and T2 value of the tumors were not declined generally after injection. The liver T2 signal intensity was decreased after injection of both γ-Fe2O3@DMSA-DG NPs and γ-Fe2O3@DMSA NPs, and T2 signal intensity of the brain and muscle did not show significant changes. γ-Fe2O3@DMSA-DG NPs has an ability to target glucose receptors overexpressed in tumors, and may serve as a MRI contrast agent for tumor detection.

Clinical optical coherence tomography of early articular cartilage degeneration in patients with degenerative meniscal tears

Quantitative and nondestructive methods for clinical diagnosis and staging of articular cartilage degeneration are important to the evaluation of potential disease-modifying treatments in osteoarthritis (OA). Optical coherence tomography (OCT) is a novel imaging technology that can generate microscopic-resolution cross-sectional images of articular cartilage in near real-time. This study tested the hypotheses that OCT can be used clinically to identify early cartilage degeneration and that OCT findings correlate with magnetic resonance imaging (MRI) T2 values and arthroscopy results. Patients undergoing arthroscopy for degenerative meniscal tears were recruited under Institutional Review Board-approved protocols. Thirty consecutive subjects completing preoperative 3.0T MRI, arthroscopy, and intraoperative OCT comprised the study group. Qualitative and quantitative OCT results and MRI T2 values were compared with modified Outerbridge cartilage degeneration scores (0-4 scale) assigned at arthroscopy. Arthroscopic grades showed cartilage abnormality in 23 of the 30 patients. OCT grades were abnormal in 28 of the 30 patients. Both qualitative and quantitative OCT strongly correlated with the arthroscopy results (P = 0.004 and P = 0.0002, respectively, by Kruskal-Wallis test). Neither the superficial nor the deep cartilage T2 values correlated with the arthroscopy results. The quantitative OCT results correlated with the T2 values in the superficial cartilage (Pearson's r = 0.39, P = 0.03). These data show that OCT can be used clinically to provide qualitative and quantitative assessments of early articular cartilage degeneration that strongly correlate with arthroscopy results. The correlation between the quantitative OCT values and T2 values for the superficial cartilage further supports the utility of OCT as a clinical research tool, providing quantifiable microscopic resolution data on the articular cartilage structure. New technologies for nondestructive quantitative assessment of human articular cartilage degeneration may facilitate the development of strategies to delay or prevent the onset of OA.

Functional cartilage MRI T2 mapping: evaluating the effect of age and training on knee cartilage response to running

To characterize effects of age and physical activity level on cartilage thickness and T2 response immediately after running. Institutional review board approval was obtained and all subjects provided informed consent prior to study participation. Cartilage thickness and magnetic resonance imaging (MRI) T2 values of 22 marathon runners and 15 sedentary controls were compared before and after 30 min of running. Runner and control groups were stratified by age<or=45 and >or=46 years. Multi-echo [(Time to Repetition (TR)/Time to Echo (TE) 1500 ms/9-109 ms)] MR images obtained using a 3.0 T scanner were used to calculate thickness and T2 values from the central femoral and tibial cartilage. Baseline cartilage T2 values, and change in cartilage thickness and T2 values after running were compared between the four groups using one-way analysis of variance (ANOVA). After running MRI T2 values decreased in superficial femoral (2 ms-4 ms) and tibial (1 ms-3 ms) cartilage along with a decrease in cartilage thickness: (femoral: 4%-8%, tibial: 0%-12%). Smaller decrease in cartilage T2 values were observed in the middle zone of cartilage, and no change was observed in the deepest layer. There was no difference cartilage deformation or T2 response to running as a function of age or level of physical activity. Running results in a measurable decrease in cartilage thickness and MRI T2 values of superficial cartilage consistent with greater compressibility of the superficial cartilage layer. Age and level of physical activity did not alter the T2 response to running.