Image registration improves human knee cartilage T1 mapping with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC)

Objectives

To evaluate the effect of automated registration in delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) of the knee on the occurrence of movement artefacts on the T1 map and the reproducibility of region-of-interest (ROI)-based measurements.

Methods

Eleven patients with early-stage knee osteoarthritis and ten healthy controls underwent dGEMRIC twice at 3?T. Controls underwent unenhanced imaging. ROIs were manually drawn on the femoral and tibial cartilage. T1 calculation was performed with and without registration of the T1-weighted images. Automated three-dimensional rigid registration was performed on the femur and tibia cartilage separately. Registration quality was evaluated using the square root Cramér–Rao lower bound (CRLB_σ). Additionally, the reproducibility of dGEMRIC was assessed by comparing automated registration with manual slice-matching.

Results

Automated registration of the T1-weighted images improved the T1 maps as the 90% percentile of the CRLB_σ was significantly (P?<?0.05) reduced with a median reduction of 55.8 ms (patients) and 112.9 ms (controls). Manual matching and automated registration of the re-imaged T1 map gave comparable intraclass correlation coefficients of respectively 0.89/0.90 (patients) and 0.85/0.85 (controls).

Conclusions

Registration in dGEMRIC reduces movement artefacts on T1 maps and provides a good alternative to manual slice-matching in longitudinal studies.

Key Points

? Quantitative MRI is increasingly used for biomedical assessment of knee articular cartilage ? Image registration leads to more accurate quantification of cartilage quality and damage ? Movement artefacts in delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) are reduced ? Automated image registration successfully aligns baseline and follow-up dGEMRIC examinations ? Reproducibility of dGEMRIC with registration is similar to that using manual slice-matching     

Magnetic resonance imaging and histology of ovine hip joint cartilage in two age populations: a sheep model with assumed healthy cartilage

Objective

To compare morphologically normal appearing cartilage in two age groups with delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and correlate magnetic resonance imaging (MRI) findings with histology.

Materials and methods

Twenty femoral head specimens collected from ten lambs (group I) and ten young adult sheep (group II) underwent dGEMRIC and histological assessment. A region of 2 cm² with morphologically normal-appearing cartilage was marked with a surgical suture for subsequent matching of MRI and histological sections. The MRI protocol included a three-dimensional (3D) double-echo steady-state sequence for morphological cartilage assessment, a B1 pre-scan with various flip angles for B1 field heterogeneity correction, and 3D volumetric interpolated breathhold examination for T1_Gd mapping (dGEMRIC). Histological analysis was performed according to the Mankin scoring system.

Results

A total of 303 regions of interest (ROI; 101 MRI reformats matching 101 histological sections) was assessed. Twenty-six ROIs were excluded owing to morphologically apparent cartilage damage or insufficient MR image quality. Therefore, 277 ROIs were analyzed. Histological analyses revealed distinct degenerative changes in various cartilage samples of group II (young adult sheep). Corresponding T1_Gd values were significantly lower in the group of sheep (mean T1_Gd?=?540.4 ms) compared with the group of lambs (mean T1_Gd?=?623.6 ms; p?<?0.001).

Conclusions

Although morphologically normal, distinct cartilage degeneration may be present in young adult sheep cartilage. dGEMRIC can reveal these changes and may be a tool for the assessment of early cartilage degeneration.     

T2* mapping and delayed gadolinium-enhanced magnetic resonance imaging in cartilage (dGEMRIC) of glenohumeral cartilage in asymptomatic volunteers at 3 T

Objectives

To establish baseline T2* and T1_Gd values of glenohumeral cartilage at 3 T.

Methods

Forty asymptomatic volunteers (mean age: 24.8?±?2.2 years) without shoulder abnormalities were included. The MRI protocol comprised a double-echo steady-state (DESS) sequence for morphological cartilage evaluation, a gradient-echo multiecho sequence for T2* assessment, and a gradient-echo dual-flip-angle sequence for T1_Gd mapping. Statistical assessment involved a one-way analysis of variance (ANOVA) to identify the differences between various regions of the glenohumeral joint and intraclass correlation (ICC) analysis comparing repetitive T2* and T1_Gd measures to assess intra- and interobserver reliability.

Results

Both techniques revealed significant differences between superior and inferior glenohumeral cartilage demonstrating higher T2* (26.2 ms vs. 23.2 ms, P value?<?0.001) and T1_Gd (750.1 ms vs. 720.2 ms, P value?=?0.014) values in the superior regions. No trend was observed in the anterior-posterior measurement (P value range: 0.279–1.000). High intra- and interobserver agreement (ICC value range: 0.895–0.983) was noted for both T2* and T1_Gd mapping.

Conclusions

T2* and T1_Gd mapping are reliable in the assessment of glenohumeral cartilage. The values from this study can be used for comparison to identify cartilage degeneration in patients suffering from shoulder joint abnormalities.

Key Points

? T2* mapping and dGEMRIC are sensitive to collagen degeneration and proteoglycan depletion. ? This study aimed to establish baseline T2*/dGEMRIC values of glenohumeral cartilage. ? Both techniques revealed significant differences between superior and inferior glenohumeral cartilage. ? High intra-/interreader agreement was noted for both T2* mapping and dGEMRIC. ? These baseline normal values should be useful when identifying potential degeneration.     

7 Tesla quantitative hip MRI: T1, T2 and T2* mapping of hip cartilage in healthy volunteers

Objectives

To evaluate the technical feasibility and applicability of quantitative MR techniques (delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), T2 mapping, T2* mapping) at 7 T MRI for assessing hip cartilage.

Methods

Hips of 11 healthy volunteers were examined at 7 T MRI with an 8-channel radiofrequency transmit/receive body coil using multi-echo sequences for T2 and T2* mapping and a dual flip angle gradient-echo sequence before (T1₀) and after intravenous contrast agent administration (T1_Gd; 0.2 mmol/kg Gd-DTPA^2? followed by 0.5 h of walking and 0.5 h of rest) for dGEMRIC. Relaxation times of cartilage were measured manually in 10 regions of interest. Pearson’s correlations between R1_delta?=?1/T1_Gd???1/T1₀ and T1_Gd and between T2 and T2* were calculated. Image quality and the delineation of acetabular and femoral cartilage in the relaxation time maps were evaluated using discrete rating scales.

Results

High correlations were found between R1_delta and T1_Gd and between T2 and T2* relaxation times (all p?<?0.01). All techniques delivered diagnostic image quality, with best delineation of femoral and acetabular cartilage in the T2* maps (mean 3.2 out of a maximum of 4 points).

Conclusions

T1, T2 and T2* mapping of hip cartilage with diagnostic image quality is feasible at 7 T. To perform dGEMRIC at 7 T, pre-contrast T1 mapping can be omitted.

Key Points

? dGEMRIC of hip cartilage with diagnostic image quality is feasible at 7 T. ? To perform dGEMRIC at 7 T, pre-contrast T1 mapping can be omitted. ? T2(*) mapping of hip cartilage with diagnostic image quality is feasible at 7 T. ? T2 and T2* relaxation times of cartilage were highly correlated at 7 T. ? Best delineation of femoral and acetabular cartilage was found in T2* maps.

     

An in vitro comparative study of T2 and T2* mappings of human articular cartilage at 3-Tesla MRI using histology as the standard of reference

Objective

The aim of this study was to evaluate the correlations between T2 value, T2* value, and histological grades of degenerated human articular cartilage.

Materials and methods

T2 mapping and T2* mapping of nine tibial osteochondral specimens were obtained using a 3-T MRI after total knee arthroplasty. A total of 94 ROIs were analyzed. Histological grades were assessed using the David–Vaudey scale. Spearman’s rho correlation analysis and Pearson’s correlation analysis were performed.

Results

The mean relaxation values in T2 map with different histological grades (0, 1, 2) of the cartilage were 51.9?±?9.2 ms, 55.8?±?12.8 ms, and 59.6?±?10.2 ms, respectively. The mean relaxation values in T2* map with different histological grades (0, 1, 2) of the cartilage were 20.3?±?10.3 ms, 21.1?±?12.4 ms, and 15.4?±?8.5 ms, respectively. Spearman’s rho correlation analysis confirmed a positive correlation between T2 value and histological grade (ρ?=?0.313, p?<?0.05). Pearson’s correlation analysis revealed a significant negative correlation between T2 and T2* (r?=??0.322, p?<?0.05). Although T2* values showed a decreasing trend with an increase in cartilage degeneration, this correlation was not statistically significant in this study (ρ?=??0.192, p?=?0.129).

Conclusions

T2 mapping was correlated with histological degeneration, and it may be a good biomarker for osteoarthritis in human articular cartilage. However, the strength of the correlation was weak (ρ?=?0.313). Although T2* values showed a decreasing trend with an increase in cartilage degeneration, the correlation was not statistically significant. Therefore, T2 mapping may be more appropriate for the initial diagnosis of articular cartilage degeneration in the knee joint. Further studies on T2* mapping are needed to confirm its reliability and mechanism in cartilage degeneration.     

T1rho MRI of menisci and cartilage in patients with osteoarthritis at 3T

Objective

To assess and compare subregional and whole T1rho values (median ± interquartile range) of femorotibial cartilage and menisci in patients with doubtful (Kellgren–Lawrence (KL) grade 1) to severe (KL4) osteoarthritis (OA) at 3T.

Materials and methods

30 subjects with varying degrees of OA (KL1–4, 13 females, 17 males, mean age ± SD = 63.9 ± 13.1 years) were evaluated on a 3T MR scanner using a spin-lock-based 3D GRE sequence for T1rho mapping. Clinical proton density (PD)-weighted fast spin echo (FSE) images in sagittal (without fat saturation), axial, and coronal (fat-saturated) planes were acquired for cartilage and meniscus Whole-organ MR imaging score (WORMS) grading. Wilcoxon rank sum test was performed to determine whether there were any statistically significant differences between subregional and whole T1rho values of femorotibial cartilage and menisci in subjects with doubtful to severe OA.

Results

Lateral (72 ± 10 ms, median ± interquartile range) and medial (65 ± 10 ms) femoral anterior cartilage subregions in moderate–severe OA subjects had significantly higher T1rho values (P < 0.05) than cartilage subregions and whole femorotibial cartilage in doubtful–minimal OA subjects. There were statistically significant differences in meniscus T1rho values of the medial posterior subregion of subjects with moderate–severe OA and T1rho values of all subregions and the whole meniscus in subjects with doubtful–minimal OA. When evaluated based on WORMS, statistically significant differences were identified in T1rho values between the lateral femoral anterior cartilage subregion in patients with WORMS5–6 (advanced degeneration) and whole femorotibial cartilage and all cartilage subregions in patients with WORMS0–1 (normal).

Conclusion

T1rho values are higher in specific meniscus and femorotibial cartilage subregions. These findings suggest that regional damage of both femorotibial hyaline cartilage and menisci may be associated with osteoarthritis.     

Smoking increases the risk of early meniscus repair failure

Purpose

The goal of this study is to determine whether patients who smoke cigarettes at the time of surgery are at significantly increased risk of early meniscus repair failure relative to non-smokers.

Methods

Retrospective chart review identified 64 current smokers within a series of 444 consecutive patients who underwent meniscus repair during a 7 years period. Fifty-two of these 64 smokers were available for follow-up and were matched by age, sex, and ACL status with non-smokers from the same cohort. Records of these 104 patients with a total of 120 meniscus repairs were reviewed to identify meniscus repair failure (defined as repeat surgery on the index meniscus) during the median 13-month (range: 3–79 months) follow-up period.

Results

The smoking and non-smoking groups were similar in age, sex, ACL status, BMI, meniscus repair technique, and meniscus involved. Meniscus repair failure occurred in 19 of the 112 menisci in 104 patients, for an overall failure risk of 17 %. Of the 19 failures, 14 occurred in 79 repaired medial menisci (18 % failure risk) and 5 occurred in 33 repaired lateral menisci (15 % failure risk). Meniscus repair failure occurred in significantly more smokers (15 failures in 56 menisci in 52 patients ?27 % failure risk) than non-smokers (4 failures in 56 menisci in 52 patients ?7 % failure risk) (p = 0.0076).

Conclusions

Smoking is associated with significantly increased risk of early meniscus repair failure as defined by the incidence of repeat surgery on the index meniscus.

Level of evidence

III.

     

Weak associations between structural changes on MRI and symptoms,function and muscle strength in relation to knee osteoarthritis

Purpose

To explore associations between MRI-defined structural abnormalities and clinical features related to knee osteoarthritis (OA).

Methods

Structural and clinical knee OA features were assessed in 87 women (45 with knee OA symptoms). Structural features were quantified by the Kellgren and Lawrence grade on radiography and by the Boston-Leeds Osteoarthritis Knee Score on MRI. Clinical features were assessed using the Knee Injury and Osteoarthritis Outcome Score, functional tests and muscle strength measurements. Associations were examined using regression analyses.

Results

Limited significant associations between structural and clinical features were found. An increased meniscal signal was associated with more pain/symptoms (P < 0.027). An anterior cruciate ligament tear was associated with poorer stair climbing test performance (P = 0.045). In a stepwise linear regression model, patellofemoral cartilage integrity and pain explained 28 % of the isometric quadriceps strength variability. The amount of cartilage lesions, loose bodies and pain explained 38 % of the isokinetic quadriceps strength variability. Synovitis/effusion and patellofemoral cartilage integrity combined with pain explained 34 % of the isometric hamstring strength variability.

Conclusion

Although MRI-detected cartilage lesions, synovitis/effusion and loose bodies did explain part of the muscle strength variability, results suggest that MRI does not improve the link between joint degeneration and the clinical expression of knee OA. MRI contributes less than expected to the understanding of pain and function in knee OA and possibly offers little opportunity to develop structure-modifying treatments in knee OA that could influence the patient’s pain and function.

Level of evidence

Case series with no comparison groups, Level IV.     

The in vivo effects of unloading and compression on T1-Gd (dGEMRIC) relaxation times in healthy articular knee cartilage at 3.0 Tesla

Purpose

The purpose was to investigate the in vivo effects of unloading and compression on T1-Gd relaxation times in healthy articular knee cartilage.

Materials and methods

Ten volunteers were enrolled, and dGEMRIC images of their right knee joints were obtained using 3.0-T MR at three timepoints: directly following exercise (“baseline”), approximately 15 min after unloading (“unloading”) and during application of a compressive force (50% of the body weight) generated by a loading device via a footplate (“compression”).

Results

Our analysis of variance of pooled data from all cartilage zones demonstrated a significant mean T1-Gd decrease of 56.6 ms between baseline and compression (p?<?0.001), and a significant mean decrease of 42.1 ms between unloading and compression (p?<?0.001). No significant difference was found between baseline and unloading. Higher mean T1-Gd values were observed in the cartilage contact zone (central femoral and tibial zones; 698.3?±?162.2 ms) than in the non-contact zone (anterior and posterior femoral and tibial zones, and dorsal femoral zone; 662.9?±?149.3 ms; p?<?0.01).

Conclusion

T1-Gd times appear to be sensitive to mechanical cartilage stress, and thus, further studies are warranted that investigate the relationship between the biochemical load response and the biomechanical properties of articular cartilage.     

The application of T1 and T2 relaxation time and magnetization transfer ratios to the early diagnosis of patellar cartilage osteoarthritis

Objectives

We compare the T1 and T2 relaxation times and magnetization transfer ratios (MTRs) of normal subjects and patients with osteoarthritis (OA) to evaluate the ability of these techniques to aid in the early diagnosis and treatment of OA.

Materials and methods

The knee joints in 11 normal volunteers and 40 patients with OA were prospectively evaluated using T1 relaxation times as measured using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), T2 relaxation times (multiple spin-echo sequence, T2 mapping), and MTRs. The OA patients were further categorized into mild, moderate, and severe OA.

Results

The mean T1 relaxation times of the four groups (normal, mild OA, moderate OA, and severe OA) were: 487.3?±?27.7, 458.0?±?55.9, 405.9?±?57.3, and 357.9?±?36.7 respectively (p?<0.001). The mean T2 relaxation times of the four groups were: 37.8?±?3.3, 44.0?±?8.5, 50.9?±?9.5, and 57.4?±?4.8 respectively (p?<?0.001). T1 relaxation time decreased and T2 relaxation time increased with worsening degeneration of patellar cartilage. The result of the covariance analysis showed that the covariate age had a significant influence on T2 relaxation time (p?<?0.001). No significant differences between the normal and OA groups using MTR were noted.

Conclusion

T1 and T2 relaxation times are relatively sensitive to early degenerative changes in the patellar cartilage, whereas the MTR may have some limitations with regard to early detection of OA. In addition, The T1 and T2 relaxation times negatively correlate with each other, which is a novel finding.     

Meniscal T1rho and T2 measured with 3.0T MRI increases directly after running a marathon

Purpose

To prospectively evaluate changes in T1rho and T2 relaxation time in the meniscus using 3.0?T MRI in asymptomatic knees of marathon runners and to compare these findings with those of age-matched healthy subjects.

Material and methods

Thirteen marathon runners underwent 3.0?T MRI including T1rho and T2 mapping sequences before, 48?C72?h after, and 3?months after competition. Ten controls were examined at baseline and after 3?months. All images were analyzed by two musculoskeletal radiologists identifying and grading cartilage, meniscal, ligamentous. and other knee abnormalities with WORMS scores. Meniscal segmentation was performed to generate T1rho and T2 maps in six compartments.

Results

No differences in morphological knee abnormalities were found before and after the marathon. However, all marathon runners showed a significant increase in T1rho and T2 values after competition in all meniscus compartments (p?Conclusion T2 values in menisci have the potential to be used as biomarkers for identifying reversible meniscus matrix changes indicating potential tissue damage. T1rho values need further study, but may be a valuable marker for diagnosing early, degenerative changes in the menisci following exercise.     

Feasibility of in vivo diffusion tensor imaging of articular cartilage with coverage of all cartilage regions

Objectives

To investigate the value of diffusion tensor imaging (DTI) of articular cartilage to differentiate healthy from osteoarthritis (OA) subjects in all cartilage regions.

Methods

DTI was acquired sagittally at 7 T in ten healthy and five OA (Kellgren-Lawrence grade 2) subjects with a line scan diffusion tensor sequence (LSDTI). Three healthy volunteers and two OA subjects were examined twice to assess the test-retest reproducibility. Averaged mean diffusivity (MD) and fractional anisotropy (FA) were calculated in each cartilage region (femoral trochlea, lateral and medial femoral condyles, patella, and lateral and medial tibia).

Results

The test-retest reproducibility was 2.9 % for MD and 5.6 % for FA. Averaged MD was significantly increased (+20 %, p?<?0.05) in the OA subjects in the lateral femoral condyle, lateral tibia and the femoral trochlea compartments. Averaged FA presented a trend of lower values in the OA subjects (-12 %), which was only significant for the lateral tibia.

Conclusions

In vivo DTI of articular cartilage with coverage of all cartilage regions using an LSDTI sequence is feasible, shows excellent reproducibility for MD and FA, and holds potential for the diagnosis of OA.

Key points

? DTI of articular cartilage is feasible at 7 T in all cartilage regions ? DTI of articular cartilage can potentially differentiate healthy and OA subjects     

In vivo evaluation of biomechanical properties in the patellofemoral joint after matrix-associated autologous chondrocyte transplantation by means of quantitative T2 MRI

Purpose

To determine in vivo biomechanical properties of articular cartilage and cartilage repair tissue of the patella, using biochemical MRI by means of quantitative T2 mapping.

Methods

Twenty MR scans were achieved at 3T MRI, using a new 8-channel multi-function coil allowing controlled bending of the knee. Multi-echo spin-echo T2 mapping was prepared in healthy volunteers and in age- and sex-matched patients after matrix-associated autologous chondrocyte transplantation (MACT) of the patella. MRI was performed at 0° and 45° of flexion of the knee after 0 min and after 1 h. A semi-automatic region-of-interest analysis was performed for the whole patella cartilage. To allow stratification with regard to the anatomical (collagen) structure, further subregional analysis was carried out (deep–middle–superficial cartilage layer). Statistical analysis of variance was performed.

Results

During 0° flexion (decompression), full-thickness T2 values showed no significant difference between volunteers (43 ms) and patients (41 ms). Stratification was more pronounced for healthy cartilage compared to cartilage repair tissue. During 45° flexion (compression), full-thickness T2 values within volunteers were significantly increased (54 ms) compared to patients (44 ms) (p < 0.001). Again, stratification was more pronounced in volunteers compared to patients. The volunteer group showed no significant increase in T2 values measured in straight position and in bended position. There was no significant difference between the 0- and the 60-min MRI examination. T2 values in the patient group increased between the 0- and the 60-min examination. However, the increase was only significant in the superior cartilage layer of the straight position (p = 0.021).

Conclusion

During compression (at 45° flexion), healthy patellar cartilage showed a significant increase in T2-values, indicating adaptations of water content and collagen fibril orientation to mechanical load. This could not be observed within the patella cartilage after cartilage repair (MACT) of the patella, most obvious due to a lack of biomechanical adjustment.

Level of evidence

III.     

Osteoarthritis of the patella, lateral femoral condyle and posterior medial femoral condyle correlate with range of motion

Purpose

The type of osteoarthritis and the degree of severity which causes restriction of knee range of motion (ROM) is still largely unknown. The objective of this study was to analyse the location and the degree of cartilage degeneration that affect knee range of motion and the connection, if any, between femorotibial angle (FTA) and knee ROM restriction.

Methods

Four hundreds and fifty-six knees in 230 subjects with knee osteoarthritis undergoing knee arthroplasty were included. Articular surface was divided into eight sections, and cartilage degeneration was evaluated macroscopically during the operation. Cartilage degeneration was classified into four grades based on the degree of exposure of subchondral bone. A Pearson correlation was conducted between FTA and knee flexion angle to determine whether high a degree of FTA caused knee flexion restriction. A logistic regression analysis was also conducted to detect the locations and levels of cartilage degeneration causing knee flexion restriction.

Results

No correlation was found between FTA and flexion angle (r = ?0.08). Flexion angle was not restricted with increasing FTA. Logistic regression analysis showed significant correlation between restricted knee ROM and levels of knee cartilage degeneration in the patella (odds ratio (OR) = 1.77; P = 0.01), the lateral femoral condyle (OR = 1.62; P = 0.03) and the posterior medial femoral condyle (OR = 1.80; P = 0.03).

Conclusion

For clinical relevance, soft tissue release and osteophyte resection around the patella, lateral femoral condyle and posterior medial femoral condyle might be indicated to obtain a higher degree of knee flexion angle.

Level of evidence

Case–control study, Level III.     

Delay in ACL reconstruction is associated with more severe and painful meniscal and chondral injuries

Purpose

The goal of our study was to investigate the associations between surgical delay, pain and meniscus, and articular cartilage lesions seen at the time of ACL reconstruction.

Methods

One hundred and sixty-two consecutive patients who had received ACL reconstruction were recruited. The preoperative International Knee Documentation Committee (IKDC) questionnaires, and cartilage and meniscal lesions seen at the time of surgery were analysed.

Results

Patients with surgery within 12 months were less likely to have meniscus injury (59.8/77.4 %, p = 0.032), and the meniscus injury was more likely to be salvageable. (56.3/36.0 %, p = 0.042). Patients with meniscal tear larger than 10 mm had higher pain intensity than tear <10 mm (mean 6.8/8.2, p = 0.007). Patients older than 35 years of age were more likely to suffer from cartilage injury (76.4/39.1 %, p = 0.004). Patients with cartilage lesions had longer surgical delay (mean 18.9/12.1 months, p = 0.033). The presence of meniscal tear increased the risk of cartilage lesions (p = 0.038, OR = 2.14). Patients with cartilage lesions had a greater pain frequency (mean 6.9/7.7, p = 0.048). Moderate correlation was found between the size of cartilage lesion and the frequency of pain (p = 0.013).

Conclusions

Increased surgical delay was associated with an increased incidence of meniscus and articular cartilage injuries in patients suffering from ACL tear; also, the meniscus was less likely to be salvageable. The presence of cartilage lesions was associated with an increased frequency of pain. Size of meniscal and cartilage lesions was significantly associated with pain.

Level of evidence

Retrospective comparative study, Level III.     

Cartilage quality in rheumatoid arthritis: comparison of T2* mapping, native T1 mapping, dGEMRIC, ΔR1 and value of pre-contrast imaging

Purpose

To prospectively evaluate four non-invasive markers of cartilage quality—T2* mapping, native T1 mapping, dGEMRIC and ΔR1—in healthy volunteers and rheumatoid arthritis (RA) patients.

Materials and methods

Cartilage of metacarpophalangeal (MCP) joints II were imaged in 28 consecutive subjects: 12 healthy volunteers [9 women, mean (SD) age 52.67 (9.75) years, range 30–66] and 16 RA patients with MCP II involvement [12 women, mean (SD) age 58.06 (12.88) years, range 35–76]. Sagittal T2* mapping was performed with a multi-echo gradient-echo on a 3?T MRI scanner. For T1 mapping the dual flip angle method was applied prior to native T1 mapping and 40?min after gadolinium application (delayed gadolinium-enhanced MRI of cartilage, dGEMRIC, T1_Gd). The difference in the longitudinal relaxation rate induced by gadolinium (ΔR1) was calculated. The area under the receiver operating characteristic curve (AROC) was used to test for differentiation of RA patients from healthy volunteers.

Results

dGEMRIC (AUC 0.81) and ΔR1 (AUC 0.75) significantly differentiated RA patients from controls. T2* mapping (AUC 0.66) and native T1 mapping (AUC 0.66) were not significantly different in RA patients compared to controls.

Conclusions

The data support the use of dGEMRIC for the assessment of MCP joint cartilage quality in RA. T2* and native T1 mapping are of low diagnostic value. Pre-contrast T1 mapping for the calculation of ΔR1 does not increase the diagnostic value of dGEMRIC.     

Morphological imaging and T2 and T2* mapping of hip cartilage at 7 Tesla MRI under the influence of intravenous gadolinium

Objectives

To investigate the influence of intravenous gadolinium on cartilage T2 and T2* relaxation times and on morphological image quality at 7-T hip MRI.

Methods

Hips of 11 healthy volunteers were examined at 7 T. Multi-echo sequences for T2 and T2* mapping, 3D T1 volumetric interpolated breath-hold examination (VIBE) and double-echo steady-state (DESS) sequences were acquired before and after intravenous application of gadolinium according to a delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) protocol. Cartilage relaxation times were measured in both scans. Morphological sequences were assessed quantitatively using contrast ratios and qualitatively using a 4-point Likert scale. Student’s t-test, Pearson’s correlation (ρ) and Wilcoxon sign-rank test were used for statistical comparisons.

Results

Pre- and post-contrast T2 and T2* values were highly correlated (T2: acetabular: ρ?=?0.76, femoral: ρ?=?0.77; T2*: acetabular: ρ?=?0.80, femoral: ρ?=?0.72). Gadolinium enhanced contrasts between cartilage and joint fluid in DESS and T1 VIBE according to the qualitative (p?=?0.01) and quantitative (p?<?0.001) analysis. The delineation of acetabular and femoral cartilage and the labrum predominantly improved with gadolinium.

Conclusions

Gadolinium showed no relevant influence on T2 or T2* relaxation times and improved morphological image quality at 7 T. Therefore, morphological and quantitative sequences including dGEMRIC can be conducted in a one-stop-shop examination.

Key Points

? Hip cartilage T2 values correlate highly before and after gadolinium at 7 T ? Hip cartilage T2* values correlate highly before and after enhancement at 7 T ? Morphological hip cartilage imaging benefits from intravenous gadolinium at 7 T ? The delineation of acetabular and femoral cartilage can be improved by gadolinium ? Morphological and quantitative sequences including dGEMRIC can be combined as a one-stop-shop examination

     

Relationship between knee alignment and T1ρ values of articular cartilage and menisci in patients with knee osteoarthritis

Objective

To assess the relationship between knee alignment and subregional T1ρ values of the femorotibial cartilage and menisci in patients with mild (Kellgren–Lawrence grade 1) to moderate (KL3) osteoarthritis (OA) at 3 T.

Materials and methods

26 subjects with a clinical diagnosis of KL1-3 OA were included and subdivided into three subgroups: varus, valgus, and neutral. All subjects were evaluated on a 3 T MR scanner. Mann–Whitney and Wilcoxon signed rank tests were performed to determine any statistically significant differences in subregional T1ρ values of femorotibial cartilage and menisci among the three subgroups of KL1-3 OA patients.

Results

Medial femoral anterior cartilage subregion in varus group had significantly higher (p < 0.05) T1ρ values than all cartilage subregions in valgus group. Medial tibial central cartilage subregion had significantly higher T1ρ values (p < 0.05) than lateral tibial central cartilage subregion in varus group. The posterior horn of the medial meniscus in neutral group had significantly higher T1ρ values (p < 0.0029) than all meniscus subregions in valgus group.

Conclusion

There exists some degree of association between knee alignment and subregional T1ρ values of femorotibial cartilage and menisci in patients with clinical OA     

Reproducibility of dGEMRIC in assessment of hip joint cartilage: A prospective study

Purpose

To investigate the reproducibility of dGEMRIC in the assessment of cartilage health of the adult asymptomatic hip joint.

Materials and Methods

Fifteen asymptomatic volunteers (mean age, 26.3 years ± 3.0) were preliminarily studied. Any volunteer that was incidentally diagnosed with damaged cartilage on MRI (n = 5) was excluded. Ten patients that had no evidence of prior cartilage damage (mean age, 26.2 years ± 3.4) were evaluated further in this study. The reproducibility of dGEMRIC was assessed with two T1_Gd exams performed 4 weeks apart in these volunteers. The protocol involved an initial standard MRI to confirm healthy cartilage, which was then followed by dGEMRIC. The second scan included only the repeat dGEMRIC. Region of interest (ROI) analyses for T1_Gd‐measurement was performed in seven radial reformats. Statistical analysis included the student's t‐test and intra‐class correlation (ICC) measurement to assess reproducibility.

Results

Overall 70 ROIs were studied. Mean cartilage T1_Gd values at various loci ranged from 560.9 ms to 684.4 ms at the first set of readings and 551.5 ms to 662.2 ms in the second one. The mean difference per region of interest between the two T1_Gd‐measurements ranged from 21.4 ms (3.7%) to 45.0 ms (6.8%), which was not found to be statistically significant (P = 0.153). There was a high reproducibility detected (ICC range, 0.667–0.915). Intra‐ and Inter‐observer analyses proved a high agreement for T1_Gd assessment (0.973 and 0.932).

Conclusion

We found dGEMRIC to be a reliable tool in the assessment of cartilage health status in adult hip joints. J. Magn. Reson. Imaging 2009;30:224–228. © 2009 Wiley‐Liss, Inc.     

Quantitative MRI in the evaluation of articular cartilage health: reproducibility and variability with a focus on T2 mapping

Purpose

Early diagnosis of cartilage degeneration and longitudinal tracking of cartilage health including repair following surgical intervention would benefit from the ability to detect and monitor changes of the articular cartilage non-invasively and before gross morphological alterations appear.

Methods

Quantitative MR imaging has shown promising results with various imaging biomarkers such as T2 mapping, T1 rho and dGEMRIC demonstrating sensitivity in the detection of biochemical alterations within tissues of interest. However, acquiring accurate and clinically valuable quantitative data has proven challenging, and the reproducibility of the quantitative mapping technique and its values are essential. Although T2 mapping has been the focus in this discussion, all quantitative mapping techniques are subject to the same issues including variability in the imaging protocol, unloading and exercise, analysis, scanner and coil, calculation methods, and segmentation and registration concerns.

Results

The causes for variability between time points longitudinally in a patient, among patients, and among centres need to be understood further and the issues addressed.

Conclusions

The potential clinical applications of quantitative mapping are vast, but, before the clinical community can take full advantage of this tool, it must be automated, standardized, validated, and have proven reproducibility prior to its implementation into the standard clinical care routine.