***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Purpose The goal of this study is to compare the cartilage of anterior cruciate ligament (ACL)-reconstructed and uninjured contralateral knees using T1ρ MRI 12–16 months after ACL reconstructions . Methods Eighteen patients with ACL-reconstructed knees ( 10 women , 8 men , mean age = 38.3 ± 7.8 years ) were studied using 3 T MRI . Injured and contralateral knee MR studies were acquired 12–16 months post-operatively . Cartilage sub-compartment T1ρ values of each injured knee were compared with the contralateral knee ’s values . Subgroup analysis of sub-compartment T1ρ values in both knees was performed between patients with and without meniscal tears at the time of ACL reconstruction using a paired Student ’s t test . Results In ACL-injured knees , the T1ρ values of the medial tibia ( MT ) and medial femoral condyle ( MFC ) were significantly elevated at 12–16 months follow-up compared to contralateral knees . Patients with a medial meniscal tear had higher MFC and MT T1ρ values compared to respective regions in contralateral knees . Patients with lateral meniscal tears had higher lateral femoral condyle and LT T1ρ values compared to respective regions in contralateral knees . There were no differences between the injured and contralateral knees of patients without meniscal tears . Conclusions T1ρ MRI can detect significant changes in the medial compartments ’ cartilage matrix of ACL-reconstructed knees at 1 year post-operatively compared to contralateral knees . The presence of a meniscal tear at the time of ACL reconstruction is a risk factor for cartilage matrix degeneration in the femorotibial compartments on the same side as the meniscal tear Introduction The goals of this study were ( i ) to compare the prevalence of focal knee abnormalities , the mean cartilage T2 relaxation time , and the spatial distribution of cartilage magnetic resonance ( MR ) T2 relaxation times between subjects with and without risk factors for Osteoarthritis ( OA ) , ( ii ) to determine the relationship between MR cartilage T2 parameters , age and cartilage morphology as determined with whole-organ magnetic resonance imaging scores ( WORMS ) and ( iii ) to assess the reproducibility of WORMS scoring and T2 relaxation time measurements including the mean and grey level co-occurrence matrix ( GLCM ) texture parameters . Methods Subjects with risk factors for OA ( n = 92 ) and healthy controls ( n = 53 ) were r and omly selected from the Osteoarthritis Initiative ( OAI ) incidence and control cohorts , respectively . The specific inclusion criteria for this study were ( 1 ) age range 45 - 55 years , ( 2 ) body mass index ( BMI ) of 19 - 27 kg/m2 , ( 3 ) Western Ontario and McMaster University ( WOMAC ) pain score of zero and ( 4 ) Kellgren Lawrence ( KL ) score of zero at baseline .  3.0 Tesla MR images of the right knee were analyzed using morphological gradings of cartilage , bone marrow and menisci ( WORMS ) as well as compartment specific cartilage T2 mean and heterogeneity . Regression models adjusted for age , gender , and BMI were used to determine the difference in cartilage parameters between groups . Results While there was no significant difference in the prevalence of knee abnormalities ( cartilage lesions , bone marrow lesions , meniscus lesions ) between controls and subjects at risk for OA , T2 parameters ( mean T2 , GLCM contrast , and GLCM variance ) were significantly elevated in those at risk for OA . Additionally , a positive significant association between cartilage WORMS score and cartilage T2 parameters was evident . Conclusions Overall , this study demonstrated that subjects at risk for OA have both higher and more heterogeneous cartilage T2 values than controls , and that T2 parameters are associated with morphologic degeneration Summary Objective To evaluate  patient-specific patellofemoral joint ( PFJ ) cartilage  3 years postoperatively using T2 mapping magnetic resonance imaging and the uninjured contralateral side as control . Hypothesis The cartilage of the PFJ in the anterior cruciate ligament ( ACL ) reconstructed knees would show increased T2 values compared to the uninjured contralateral knees at 3-year follow-up , and the femoral ( trochlear ) cartilage would be more susceptible than the patella in degeneration in ACL-reconstructed knees . Methods Ten patients with clinical ly successful ACL-reconstructed knees were prospect ively enrolled 3 years postoperatively .  Sagittal images of both knees were obtained using T2 mapping . Cartilage over the medial , central , and lateral regions of the trochlea and patella was divided into superficial and deep regions . Average T2 values of the cartilage at each region of interest of the ACL-reconstructed and uninjured contralateral knees were compared for each individual patient . Results Overall , the T2 values at the superficial layers of the medial and central trochlear cartilage of the ACL-reconstructed knees were significantly higher than those of the uninjured contralateral knees by 4.23 ± 9.09 milliseconds ( 8.9 % ; p = 0.043 ) and 5.94 ± 8.12 milliseconds ( 10.9 % ; p = 0.019 ) , respectively . No significant difference was found in other cartilage areas of the trochlea and patella . In individual patient analysis , increased T2 values of ACL-reconstructed knees were found in all 10 patients in at least one superficial region and eight patients in at least one deep region of the trochlear cartilage , five patients in at least one superficial region , and eight patients in at least one deep region of the patellar cartilage . Conclusion Despite a clinical ly satisfactory ACL reconstruction ( with negative anteroposterior drawer and pivot shift tests ) , all patients showed at least one region with increased T2 value of the PFJ cartilage 3 years after ACL reconstruction , especially at the medial compartment of the trochlear cartilage . The Translational Potential of this Article Little data has been reported on PFJ cartilage condition after ACL reconstruction . This study could help develop noninvasive diagnostic methods for detection of early PFJ cartilage degeneration after ACL reconstruction T(1rho ) describes the spin-lattice relaxation in the rotating frame and has been proposed for detecting damage to the cartilage collagen-proteoglycan matrix in osteoarthritis . In this study , a multi-slice T(1rho ) imaging method for knee cartilage was developed using spin-lock techniques and a spiral imaging sequence . The adverse effect of T(1 ) regrowth during the multi-slice acquisition was eliminated by RF cycling . Agarose phantoms with different concentrations , 10 healthy volunteers , and 9 osteoarthritis patients were scanned at 3 T . T(1rho ) values decreased as agarose concentration increased . T(1rho ) values obtained with imaging methods were compared with those obtained with spectroscopic methods . T(1rho ) values obtained during multi-slice acquisition were vali date d with those obtained in a single slice acquisition . Reproducibility was assessed using the average coefficient of variation of median T(1rho ) , which was 0.68 % in phantoms and 4.8 % in healthy volunteers . There was a significant difference ( P = 0.002 ) in the average T(1rho ) within patellar and femoral cartilage between controls ( 45.04 + /- 2.59 ms ) and osteoarthritis patients ( 53.06 + /- 4.60 ms ) . A significant correlation was found between T(1rho ) and T(2 ) ; however , the difference of T(2 ) was not significant between controls and osteoarthritis patients . The results suggest that T(1rho ) relaxation times may be a promising clinical tool for osteoarthritis detection and treatment monitoring Background : Patellofemoral pain ( PFP ) is a common condition and often presents without evidence of arthritis on radiographs . Magnetic resonance imaging ( MRI ) has shown good correlation between T1ρ and T2 relaxation times and changes in the cartilage matrix , but as of yet , there are limited data in the literature utilizing these modalities to evaluate the patellofemoral joint . Hypothesis : Patients with PFP and patellar tilt will show longer T1ρ relaxation times in the lateral facets of their patella but no difference in T2 values . Study Design : Cross-sectional study ; Level of evidence , 3 . Methods : A total of 20 patients aged 18 to 45 years with anterior knee pain , patellar tilt , and no evidence of osteoarthritis were identified and consented to undergo MRI including axial T1ρ and T2 relaxation time mapping sequences . Knee cartilage was segmented on spoiled gradient recalled acquisition in steady state ( SPGR ) images using a spline-based algorithm . These results were then compared with those of 10 age-matched controls . Results : The mean T1ρ values of the lateral facets were significantly elevated in patients with PFP compared with controls ( 46.33 ± 4.92 ms vs 42.32 ± 3.67 ms , respectively ; P = .031 ) , while no significant difference was observed in the medial facets ( 42.20 ± 5.55 ms vs 41.42 ± 4.09 ms , respectively ; P = .69 ) . Significantly higher mean T1ρ values were noted in the lateral facets of the patients with PFP ( 46.33 ms ) compared with the medial facets ( 42.20 ms ) ( P = .0001 ) , while no significant differences in T1ρ values were observed between the medial and lateral facets of the controls ( P = .502 ) . No significant differences were noted in T2 relaxation times . A high correlation was noted between the mean T1ρ values of the whole patella of patients with PFP and the degree of patellar tilt ( r = 0.72 ) . Conclusion : There were significantly higher T1ρ values in the lateral facets of patients with PFP and patellar tilt that were not seen in control patients . These higher values approach the numbers seen in patients with early osteoarthritis OBJECTIVE To prospect ively compare chemical-exchange saturation-transfer ( CEST ) with delayed gadolinium-enhanced MRI of cartilage ( dGEMRIC ) and T2 mapping to assess the biochemical cartilage properties of the knee . METHOD Sixty-nine subjects were prospect ively included ( median age , 42 years ; male/female = 32/37 ) in three cohorts : 10 healthy volunteers , 40 patients with clinical ly suspected cartilage lesions , and 19 patients about 1 year after microfracture therapy . T2 mapping , dGEMRIC , and CEST were performed at a 3 T MRI unit using a 15-channel knee coil . Parameter maps were evaluated using region-of-interest analysis of healthy cartilage , areas of chondromalacia and repair tissue . Differentiation of damaged from healthy cartilage was assessed using receiver-operating characteristic ( ROC ) analysis . RESULTS Chondromalacia grade 2 - 3 had significantly higher CEST values ( P = 0.001 ) , lower dGEMRIC ( T1- ) values ( P < 0.001 ) and higher T2 values ( P < 0.001 ) when compared to the normal appearing cartilage . dGEMRIC and T2 mapping correlated moderately negative ( Spearman coefficient r = -0.56 , P = 0.0018 ) and T2 mapping and CEST moderately positive ( r = 0.5 , P = 0.007 ) , while dGEMRIC and CEST did not significantly correlate ( r = -0.311 , P = 0.07 ) . The repair tissue revealed lower dGEMRIC values ( P < 0.001 ) and higher CEST values ( P < 0.001 ) with a significant negative correlation ( r = -0.589 , P = 0.01 ) , whereas T2 values were not different ( P = 0.54 ) . In healthy volunteers ' cartilage , CEST and dGEMRIC showed moderate positive correlation ( r = 0.56 ) , however not reaching significance ( P = 0.09 ) . ROC- analysis demonstrated non-significant differences of T2 mapping vs CEST ( P = 0.14 ) , CEST vs dGEMRIC ( P = 0.89 ) , and T2 mapping vs dGEMRIC ( P = 0.12 ) . CONCLUSION CEST is able to detect normal and damaged cartilage and is non-inferior in distinguishing both when compared to dGEMRIC and T2 mapping PURPOSE To compare multicomponent T2 parameters of the articular cartilage of the knee joint measured by using multicomponent driven equilibrium single-shot observation of T1 and T2 ( mcDESPOT ) in asymptomatic volunteers and patients with osteoarthritis . MATERIAL S AND METHODS This prospect i ve study was performed with institutional review board approval and with written informed consent from all subjects . The mcDESPOT sequence was performed in the knee joint of 13 asymptomatic volunteers and 14 patients with osteoarthritis of the knee .  Single-component T2 ( T2(Single ) ) , T2 of the fast-relaxing water component ( T2F ) and of the slow-relaxing water component ( T2S ) , and the fraction of the fast-relaxing water component ( F(F ) ) of cartilage were measured . Wilcoxon rank-sum tests and multivariate linear regression models were used to compare mcDESPOT parameters between volunteers and patients with osteoarthritis . Receiver operating characteristic analysis was used to 
    Output:
    
Conclusions T2 and T1ρ relaxation distinguish participants at risk for knee OA from healthy controls .