T1ρ and T2 mapping reveal the in vivo extracellular matrix of articular cartilage

Purpose:

To determine the relationship between changes in the extracellular matrix (ECM) and T_1ρ and T₂ values in vivo. The ECM is composed of proteoglycan (PG), collagen, and water. It has been unclear which of the ECM constituents affects T_1ρ and T₂ mapping in living human cartilage.

Materials and Methods:

Sagittal T_1ρ and T₂ maps were preoperatively obtained from 20 knee osteoarthritis patients. Osteochondral samples harvested from the resected tibial plateaus during total knee arthroplasty were consistent with the MRIs of the patients' knees. Parameters that included histological grading of cartilage degeneration, glycosaminoglycan (GAG) content (which constitutes PG), presence of collagen anisotropy and water content were evaluated along with T_1ρ and T₂ values, and statistical analysis was performed using multiple regression analysis.

Results:

T_1ρ and T₂ values were significantly correlated with the degree of cartilage degeneration (β = 0.397 and 0.357, respectively) and the GAG content (β = ?0.340 and ?0.244, respectively).

Conclusion:

The present study demonstrated that T_1ρ and T₂ values reflect the GAG content of the cartilage and can indicate cartilage degeneration in vivo. Use of these parameters can facilitate the noninvasive diagnosis and evaluation of cartilage degeneration. J. Magn. Reson. Imaging 2012;35:147‐155. © 2011 Wiley Periodicals, Inc.

     

Changes in the T2 value of cartilage after meniscus transplantation over 1 year

Objectives

To evaluate the changes in the mean T2 values of articular cartilage on serial follow-up images up to 1 year in patients who underwent lateral meniscus allograft transplantation (MAT).

Methods

Fifty-two patients who underwent lateral MAT surgery at our hospital were evaluated preoperatively and at 2 days, 6 weeks, 3 months, 6 months, and 1 year after MAT using 3.0-T magnetic resonance imaging (MRI) that included T2 mapping. T2 value changes according to the arthroscopic grading of chondromalacia were evaluated in the lateral and medial compartment. Lysholm scores were obtained pre- and postoperatively.

Results

The T2 values of cartilage were significantly increased 2 days after operation, and then gradually reduced to the baseline level after 1 year in both compartments. In morphologic assessment performed after 1 year, most areas (92.9 %) showed no interval change of chondromalacia grade. Lyshom knee scores increased significantly from the mean preoperative value of 62.5 (range, 23–95) to 89.7 (range, 64–100) at 1 year (p?<?0.001).

Conclusion

Mean T2 values of cartilage following MAT exhibited a return to baseline level after 1 year. T2 measurement can be a useful tool for quantitative evaluation of postoperative cartilage changes compared to conventional MRI.

Key Points

? T2 mapping provides objective data for longitudinal monitoring following surgery.? Increased cartilage T2 values post-MAT returned to baseline in one year.? Further studies are required to predict the chondroprotective effect of MAT.

     

T1ρ and T2 mapping of the proximal tibiofibular joint in relation to aging and cartilage degeneration

Objective

To study the effects of aging and cartilage degeneration of the proximal tibiofibular- and femorotibial joint (PTFJ, FTJ) on the cartilage of the PTFJ using T₁ρ and T₂ mapping.

Materials and methods

We performed sagittal T₁ρ and T₂ mapping of the PTFJ and FTJ on 55 subjects with knee disorders. We placed 3 regions of interest (ROIs) on images of the cartilage in the PTFJ, medial femoral condyle (MFC), and medial tibia plateau (MTP). Correlation analysis was performed for the T₁ρ and T₂ values of each ROI and the patient age and the osteoarthritic grade of the PTFJ and FTJ.

Results

The T₁ρ and T₂ values of the PTFJ were affected neither by aging nor the osteoarthritic grade of the FTJ. Values of the FTJ normalized to PTFJ values were correlated with the osteoarthritic grade of the FTJ in the MFC (r = 0.851 and 0.779, respectively) and the MTP (r = 0.635 and 0.762, respectively). There was a significant difference in the T₁ρ but not the T₂ value of the PTFJ and MFC between normal and mildly osteoarthritic cartilage of each joint.

Conclusion

We document that the T₁ρ and T₂ values of PTFJ cartilage were not affected by aging or cartilage degeneration in the FTJ. The T₁ρ value of the PTFJ may represent a useful internal standard reference for evaluating early degeneration of the FTJ.     

Imaging biomarker with T1ρ and T2 mappings in osteoarthritis – In vivo human articular cartilage study

Introduction

Osteoarthritis (OA) of the knee is a common and disabling disease worldwide. Its prevalence is increasing in view of the aging population. Changes in collagen content, its orientation and GAG content in the articular cartilage with age are the major features in knee osteoarthritis. These changes in collagen and GAG contents show no manifestation in plain radiography and conventional magnetic resonance imaging (MRI). Nevertheless, early diagnosis of the knee osteoarthritis is of paramount importance clinically in view of the evolution of putative interventions in its early stage. The aim of this project is to identify the relationships between the two imaging biomarkers (i.e. T1ρ and T2 mappings) and the GAG concentration in living human symptomatic cartilage.

Methodology

28 patients with clinical diagnosis of knee osteoarthritis were enrolled. 7 males and 16 females were recruited and their mean age was 68.1 (ranges from 53 to 84). Conventional PD sequence, T1ρ and T2 mappings were performed for each subject within 1 week before total knee arthroplasty. Articular cartilage from the lateral tibial plateau was harvested and the GAG content in cartilage was determined by using dimethylmethylene blue method. T1ρ mean and T2 values were calculated and correlate with GAG concentration statistically.

Results

The mean value T1ρ was 40.3 ± 13.5 ms, ranging from 15.3 to 69.3 ms and the mean value T2 was 31.0 ± 10.5 ms, ranging from 16.1 to 46.9 ms. The mean value of GAG content was 80.1 ± 33.3 mg, ranging from 24.9 to 166.0 mg while the mean value of GAG concentration was 267.4 ± 165.9 mg/cm³, ranging from 91.3 to 760.5 mg/cm³. T2 values were inversely correlated with GAG concentration with R² = 0.375, p = 0.001 while T1ρ values were also inversely correlated with GAG concentration with R² = 0.200, p = 0.025.

Conclusion

This in vivo study confirmed that T1ρ and T2 values correlate with the GAG concentration in living human knee cartilages which corroborate with the previous works. The later (T2 values) is found more reliable in our study and less controversial in literatures. We postulate that T2 values can serve as a non-invasive imaging biomarker in the progress of knee osteoarthritis in terms of both disease diagnosis and treatment response monitoring.     

Spectrum of T2* values in knee joint cartilage at 3 T: a cross-sectional analysis in asymptomatic young adult volunteers

Objective

To establish baseline T2* values in healthy knee joint cartilage at 3 T.

Materials and Methods

Thirty-four volunteers (mean age: 24.6?±?2.7 years) with no history or clinical findings indicative of any knee joint disease were enrolled. The protocol included a double-echo steady-state (DESS) sequence for morphological cartilage evaluation and a gradient-echo multi-echo sequence for T2* assessment. Bulk and zonal T2* values were assessed in eight regions: posterior lateral femoral condyle; central lateral femoral condyle; trochlea; patella; lateral tibial plateau; posterior medial femoral condyle; central medial femoral condyle; and medial tibial plateau. Statistical evaluation comprised a two-tailed t test and a one-way analysis of variance to identify zonal and regional differences.

Results

T2* mapping revealed higher T2* values in the superficial zone in all regions (P values?≤?0.001) except for the posterior medial femur condyle (P?=?0.087), and substantial regional differences demonstrating superior values in trochlear cartilage, intermediate values in patellar and central femoral condylar cartilage, and low T2* values in posterior femoral condylar cartilage and tibial plateau cartilage.

Conclusion

Substantial regional differences in T2* measures should be taken into consideration when conducting T2* mapping of knee joint cartilage.     

Does joint alignment affect the T2 values of cartilage in patients with knee osteoarthritis?

Objective  

To assess the relationship between T2 values of femorotibial cartilage and knee alignment in patients with clinical symptoms of medial osteoarthritis (OA).     

Longitudinal assessment of bone marrow edema-like lesions and cartilage degeneration in osteoarthritis using 3 T MR T1rho quantification

Objective  

To quantitatively assess the relationship between bone marrow edema-like lesions (BMELs) and the associated cartilage in knee osteoarthritis (OA) using T_1ρ quantification at 3 T MRI.     

Quantitative evaluation of knee cartilage and meniscus destruction in patients with rheumatoid arthritis using T1ρ and T2 mapping

ObjectiveTo calculate T1ρ and T2 values of articular cartilage and menisci in knee joints of patients with RA, and compare the values between RA patients and healthy volunteers, to gain insight into the pathogenesis of cartilage and meniscus degradation in patients with RA.Materials and methodsNine patients with RA and knee joints symptoms were enrolled in the study, twenty healthy volunteers without knee joint diseases were included as controls. Sagittal fat-saturated T1ρ and T2 mapping images were obtained on a 3T MR scanner (GE750, GE Healthcare, Waukesha, WI), using a dedicated 8-channel knee coil. In the T1rho mapping sequence, the amplitude of the spin-lock pulse was 500 Hz, spin lock durations = 10/20/30/50 ms. In the T2 mapping sequence,TR/TE were 1794/6.5, 13.4, 27, 40.7 ms. Both sequences were performed with the following parameters: flip angle (FA) = 90°, matrix: 320 × 256, FOV: 16 × 16 cm², slice thickness: 3 mm, bandwidth: 62.5 kHZ, and a total scan time of 5:11 min. T1ρ- and T2-mapping images were used for the segmentation of the articular cartilage of the patella, femoral trochlea, medial and lateral femoral condyle, medial and lateral tibial plateau. These images were also used for the segmentation of the anterior and posterior horns of the medial and lateral menisci with livewire semi-automatic segmentation algorithm of MATLAB. A Mann–Whitney U test was performed to compare the T1ρ and T2 values of the above mentioned regions between the two groups.ResultsT1ρ (Z = −3.913 to −2.121, P = 0.000–0.034) and T2 (Z = −3.866 to −2.216, P = 0.000–0.026) values of knee cartilage in patients with RA were higher than that in healthy volunteers, except the cartilage of the patella (T1ρ: Z = −1.273, P = 0.203,T2: Z = −0.236, P = 0.814) and lateral tibial plateau (T1ρ:Z = −1.037, P = 0.317). The T1ρ (Z = −1.462 to 0.572, P = 0.095–0.908) and T2 (Z = −1.461 to 0.278, P = 0.153–0.764) values of medial and lateral menisci showed no difference between the two groups.ConclusionPatients with RA exhibit diffuse knee cartilage destruction in the medial and lateral tibiofemoral joints and in the femoral trochlea. However, we found no increase in T1ρ and T2 values in menisci, this finding warrants further investigation.     

T(1ρ) and T(2) quantitative magnetic resonance imaging analysis of cartilage regeneration following microfracture and mosaicplasty cartilage resurfacing procedures

Purpose

To examine T_1ρ (T1rho) and T₂ quantitative magnetic resonance imaging (MRI) in evaluating cartilage regeneration following microfracture (MFx) and mosaicplasty (MOS) cartilage resurfacing procedures.

Materials and Methods

Eighteen patients underwent MFx and eight patients underwent MOS to treat symptomatic focal cartilage defects. Quantitative T_1ρ and T₂ maps were acquired at 3–6 months and 1 year after surgery. The area of resurfacing was identified, and T_1ρ and T₂ values for the regenerated tissue (RT) and normal cartilage (NC) were acquired. RT/NC ratios were calculated to standardize absolute T_1ρ and T₂ values. Data were prospective, cross‐sectional, and nonrandomized.

Results

T_1ρ and T₂ showed good reanalysis reproducibility for RT and NC. Significant differences between RT and NC were present following MFx at 3–6 months for T_1ρ and T₂ values as well as following MOS at 3–6 months and 1 year for T_1ρ values. Following MFx, the T₂ RT/NC ratio was significantly different between 3–6 months and 1 year (P = 0.02), while the T_1ρ RT/NC ratio approached significance (P = 0.07). Following MOS, the T_1ρ and T₂ RT/NC ratios were not significantly different between the two timepoints.

Conclusion

T_1ρ and T₂ MRI are complementary and reproducible methods for quantitatively and noninvasively monitoring regeneration of RT following MFx and MOS. J. Magn. Reson. Imaging 2010;32:914–923. © 2010 Wiley‐Liss, Inc.     

Detecting ICRS grade 1 cartilage lesions in anterior cruciate ligament injury using T1ρ and T2 mapping

Objective

The purpose of this study was to clarify the detectability of the International Cartilage Repair Society (ICRS) grade 1 cartilage lesions in anterior cruciate ligament (ACL)–injured knees using T1ρ and T2 mapping.

Materials and Methods

We performed preoperative T1ρ and T2 mapping and 3D gradient–echo with water–selective excitation (WATS) sequences on 37 subjects with ACL injuries. We determined the detectability on 3D WATS based on arthroscopic findings. The T1ρ and T2 values (ms) were measured in the regions of interest that were placed on the weight–bearing cartilage of the femoral condyle. The receiver operating characteristic (ROC) curve based on these values was constructed using the arthroscopic findings as a reference standard. The evaluation of cartilage was carried out only in the weight–bearing cartilage. The cut–off values for determining the presence of a cartilage injury were determined using each ROC curve, and the detectability was calculated for the T1ρ and T2 mapping.

Results

The cut–off values for the T1ρ and T2 were 41.6 and 41.2, respectively. The sensitivity and specificity of T1ρ were 91.2% and 89.5%, respectively, while those of T2 were 76.5% and 81.6%, respectively. For the 3D WATS images, the same values were 58.8% and 78.9%, respectively.

Conclusions

Our study demonstrated that the T1ρ and T2 values were significantly higher for ICRS grade 1 cartilage lesions than for normal cartilage and that the two mappings were able to non–invasively detect ICRS grade 1 cartilage lesions in the ACL–injured knee with a higher detectability than were 3D WATS images.     

T1rho, T2 and focal knee cartilage abnormalities in physically active and sedentary healthy subjects versus early OA patients—a 3.0-Tesla MRI study

(1) To assess the degree of focal cartilage abnormalities in physically active and sedentary healthy subjects as well as in patients with early osteoarthritis (OA). (2) To determine the diagnostic value of T2 and T1rho measurements in identifying asymptomatic physically active subjects with focal cartilage lesions. Thirteen asymptomatic physically active subjects, 7 asymptomatic sedentary subjects, and 17 patients with mild OA underwent 3.0-T MRI of the knee joint. T1rho and T2 values, cartilage volume and thickness, as well as the WORMS scores were obtained. Nine out of 13 active healthy subjects had focal cartilage abnormalities. T1rho and T2 values in active subjects with and without focal cartilage abnormalities differed significantly (p < 0.05). T1rho and T2 values were significantly higher (p < 0.05) in early OA patients compared to healthy subjects. T1rho measurements were superior to T2 in differentiating OA patients from healthy subjects, yet T1rho was moderately age-dependent. (1) Active subjects showed a high prevalence of focal cartilage abnormalities and (2) active subjects with and without focal cartilage abnormalities had different T1rho and T2 composition of cartilage. Thus, T1rho and T2 could be a parameter suited to identify active healthy subjects at higher risk for developing cartilage pathology.     

Human cartilage fragments in a composite scaffold for single-stage cartilage repair: an in vitro study of the chondrocyte migration and the influence of TGF-β1 and G-CSF

Purpose

Minced chondral fragments are becoming popular as a source of cells for cartilage repair, as a growing interest is developing towards one-stage procedures to treat cartilage lesions. The purpose of this study is to (A) compare cell outgrowth from cartilage fragments of adult and young donors using two different types of scaffolds and (B) evaluate the influence of transforming-growth-factor-β1 (TGF-β1) and granulocyte colony-stimulating factor (G-CSF) on chondrocyte behaviour.

Methods

In part (A) cartilage fragments from adult and young donors were either loaded onto an HA-derivative injectable paste scaffold or onto an HA-derivative membrane scaffold. Construct sections were then examined for cell counting after 1, 2 and 3 months. In part (B) only membrane scaffolds were prepared using cartilage fragments from young donors. Constructs were cultured either in standard growth medium or in the presence of specific growth factors, such as TGF-β1 or G-CSF or TGF-β1 + G-CSF. After 1 month, construct sections were examined for cell counting. Expression of chondrocyte markers (SOX9, CD151, CD49c) and proliferative markers (β-catenin, PCNA) was assessed using immunofluorescence techniques, both in unstimulated construct sections and in cells from unstimulated and stimulated construct cultures.

Results

Part (A): histological analysis showed age-dependent and time-dependent chondrocyte migration. A significant difference (p < 0.05) was observed between young and older donors at the same time point. No difference was detected between the two types of scaffolds within the same group at the same time point. Part (B): after 1 month, the number of migrating cells/area significantly increased due to exposure to TGF-β1 and/or G-CSF (p < 0.05). Immunofluorescence revealed that outgrowing cells from unstimulated scaffold sections were positive for SOX9, CD151, CD49c and G-CSF receptor. Immunofluorescence of cells from construct cultures showed an increase in β-catenin in all stimulated groups and an increased PCNA expression in G-CSF-exposed cultures (p < 0.05).

Conclusion

Outgrowing cells may represent a subset of chondrocytes undergoing a phenotypic shift towards a proliferative state. TGF-β1, and to a greater extent G-CSF, may accelerate this outgrowth. The clinical relevance of this study may involve a potential future clinical application of scaffolds preloaded with growth factors as an additional coating for chondral fragments. Indeed, a controlled delivery of G-CSF, widely employed in various clinical settings, might improve the repair process driven by minced human cartilage fragments during one-stage cartilage repair.     

Fibronectin–aggrecan complex as a marker for cartilage degradation in non-arthritic hips

Purpose

To report hip synovial fluid cytokine concentrations in hips with and without radiographic arthritis.

Methods

Patients with no arthritis (Tonnis grade 0) and patients with Tonnis grade 2 or greater hip osteoarthritis (OA) were identified from patients undergoing either hip arthroscopy or arthroplasty. Synovial fluid was collected at the time of portal establishment for those undergoing hip arthroscopy and prior to arthrotomy for the arthroplasty group. Analytes included fibronectin–aggrecan complex (FAC) as well as a standard 12 cytokine array. Variables recorded were Tonnis grade, centre-edge angle of Wiberg, as well as labrum and cartilage pathology for the hip arthroscopy cohort. A priori power analysis was conducted, and a Mann–Whitney U test and regression analyses were used with an alpha value of 0.05 set as significant.

Results

Thirty-four patients were included (17 arthroplasty, 17 arthroscopy). FAC was the only analyte to show a significant difference between those with and without OA (p < 0.001). FAC had significantly higher concentration in those without radiographic evidence of OA undergoing microfracture versus those not receiving microfracture (p < 0.05).

Conclusion

There was a significantly higher FAC concentration in patients without radiographic OA. Additionally, those undergoing microfracture had increased levels of FAC. As FAC is a cartilage breakdown product, no significant amounts may be present in those with OA. In contrast, those undergoing microfracture have focal area(s) of cartilage breakdown. These data suggest that FAC may be useful in predicting cartilage pathology in those patients with hip pain but without radiographic evidence of arthritis.

Level of evidence

Diagnostic, Level III.     

Tod in Tüten

Helium as a modern, safe and painless facility for committing suicide is communicated worldwide in internet forums and by assisted suicide organisations. Free accessible step-by-step instructions simplify the planning and accomplishment for the person wanting to die. The easy availability of information and materials explains the more frequent occurrence of helium-associated suicide particularly among the web generation. This development and the possibility of post-mortem toxicological detection of helium should be considered in routine forensic casework. Cases from the institutes of Rostock, Hamburg and Munich will be presented.     

Costal cartilage fractures in blunt polytrauma patients — a prospective clinical and radiological follow-up study

Emergency Radiology - To assess the healing of costal cartilage fractures (CCFX) in patients with blunt polytrauma with follow-up imaging and clinical examination. Effect on physical performance...     

Articular cartilage status 2 years after arthroscopic ACL reconstruction in patients with or without concomitant meniscal surgery: evaluation with 3.0T MR imaging

Purpose

To assess articular cartilage changes in the knee joint as detected on 3.0T MR imaging after 2-year follow-up in patients who underwent arthroscopic anterior cruciate ligament reconstruction (ACLR) with or without concomitant meniscal surgery.

Methods

A total of twenty-nine patients (mean age 30.3 ± 10 years), who underwent arthroscopic ACLR, received clinical and imaging follow-up at an average of 27.8 ± 4.8 months after surgery. Our patients were divided into two subgroups: eighteen patients with additional meniscal injuries at the time of arthroscopic ACLR who underwent meniscal surgery and eleven patients with intact menisci. The cartilage status of all knees at the time of arthroscopic ACLR was recorded. All patients underwent an MRI scan preoperatively and at follow-up with the same imaging protocol. Cartilage status of all knee compartments was evaluated at the time of follow-up by MR imaging and the ICRS classification.

Results

Deterioration of the cartilage status was found at all knee compartments of our study group, with respect to the number of cartilage defects. The cartilage of the lateral femoral condyle (LFC) was most severely affected, followed by patellar and medial femoral condyle (MFC) cartilage. A statistically significant relation was found between surgery of the medial meniscus and the development of new cartilage defects in LFC (p = 0.01) and MFC (p = 0.03) after adjusting for the site of meniscal surgery. The cartilage of LFC and the status of the medial meniscus were also found to be significantly related (p = 0.04). Partial meniscectomy was found to be associated with an increased incidence of new cartilage defects when compared to either meniscal repair or absence of meniscal surgery, although it was not statistically significant.

Conclusion

Development of new cartilage lesions was evident after 2-year follow-up in patients with arthroscopic ACLR as detected by MR imaging. There was a multicompartmental pattern of cartilage involvement, and the lateral compartment was most severely affected. Partial meniscectomy at the time of arthroscopic ACLR could be suggested as an additional risk factor for the progression of chondral lesions.

Level of evidence

Prospective comparative study, Level II.