T1ρ MRI Research Articles

Early degenerative changes are different between partial and complete anterior cruciate ligament injury and associate with joint instability in a skeletally immature porcine model

ObjectiveAnterior cruciate ligament (ACL) injuries are a major problem in the pediatric and adolescent populations. Some of these injuries are only partial; yet, there is limited data to inform clinical treatment of such partial tears. It is unknown how injury partial injury impacts long-term degenerative changes in the joint relative to complete injury. In this study, we hypothesized that partial (anteromedial (AM) or posterolateral (PL) bundle) tears would result in small levels of instability and degeneration relative to complete ACL tears and that the degree of degeneration would associate with joint instability. DesignPartial (isolated AM or PL bundle) or complete ACL injury was arthroscopically created in 3-month-old juvenile pigs. The contralateral limb served as a sham-operated control. Six months after injury, joint biomechanics was assessed along with cartilage and meniscus degeneration (via MRI, gross imaging, and histology). ResultsJoint laxity increases were minimal after PL bundle injury (difference relative to controls (confidence interval): 0.5 (-1.2-2.2) mm), minor after AM bundle injury (3.7 (2.0-5.4) mm), and major after ACL injury (15.8 (13.7-17.8) mm). Cartilage MRI T1ρ relaxation times increased minimally after PL bundle injury (-0.9 (-5.1-3.3) ms for lateral tibia), moderately after AM bundle injury (6.6 (1.7-11.4) ms), and substantially after ACL injury (10.8 (2.1-19.5) ms). Changes in meniscus volume followed a similar rank order. Degeneration was associated with the extent of joint destabilization. ConclusionsThese findings suggest that cartilage and meniscus degeneration in the skeletally immature joint are associated with joint laxity after partial and complete ACL injuries.

Alternating Look-Locker for quantitative T1 , T1ρ and B1 3D MRI mapping.

To develop a new MRI method, entitled alternating Look-Locker (aLL), for quantitative , , and 3D mapping. A Look-Locker scheme that alternates magnetization from +Z and -Z axes of the laboratory frame is utilized in combination with a 3D Multi-Band Sweep Imaging with Fourier Transformation (MB-SWIFT) readout. The analytical solution describing the spin evolution during aLL, as well as the correction required for segmented acquisition were derived. The simultaneous and mapping are demonstrated on an agar/saline phantom and on an in-vivo rat head. relaxation was achieved by cyclically applying magnetization preparation (MP) modules consisting of two adiabatic pulses. values in the rat brain in-vivo and in a gadobenate dimeglumine (Gd-DTPA) phantom were compared to those obtained with a previously introduced steady-state (SS) method. The accuracy and precision of the analytical solution was tested by Bloch simulations. With the application of MP modules, the aLL method provides simultaneous and maps. Conversely, without it, the method can be used for simultaneous and mapping. values were similar with both aLL and SS techniques. However, the aLL method resulted in more robust quantitative mapping compared to the SS method. Unlike the SS method, the aLL method does not require additional scans for generating maps. The proposed method offers a new flexible tool for quantitative mapping of , , and . The aLL method can also be used with readout schemes different from MB-SWIFT.

Densification: Hyaluronan Aggregation in Different Human Organs.

Hyaluronan (HA) has complex biological roles that have catalyzed clinical interest in several fields of medicine. In this narrative review, we provide an overview of HA aggregation, also called densification, in human organs. The literature suggests that HA aggregation can occur in the liver, eye, lung, kidney, blood vessel, muscle, fascia, skin, pancreatic cancer and malignant melanoma. In all these organs, aggregation of HA leads to an increase in extracellular matrix viscosity, causing stiffness and organ dysfunction. Fibrosis, in some of these organs, may also occur as a direct consequence of densification in the long term. Specific imaging evaluation, such dynamic ultrasonography, elasto-sonography, elasto-MRI and T1ρ MRI can permit early diagnosis to enable the clinician to organize the treatment plan and avoid further progression of the pathology and dysfunction.

T1ρ magnetic resonance imaging for quantitative assessment of patella cartilage in healthy subjects and athletes

Knee osteoarthritis (OA) is one of major reasons to causes pain and limit mobility for aging people. Early diagnosis of articular cartilage degeneration is of utmost importance for the prevention of OA. Thus, it is necessary to develop a novel magnetic resonance imaging technique to detect the early articular cartilage degeneration. Methods. T1ρ and T2-weighted images of the knees were obtained for 50 asymptomatic young subjects (23 men and 27 women; average age, 23.9 ± 1.8 years) and 17 Chinese National Men's hockey players (average age, 20.7 ± 1.1 years), using a 3.0-T MRI scanner. Quantitative T1ρ relaxation maps of the bilateral patella cartilage were generated by post-processing, and each map was divided into 15 regions of interest (ROIs). T1ρ values of each ROI were measured and compared between asymptomatic subjects and athletes. Results. T1ρ values of left patellar cartilage in athletes were significantly higher than those in healthy subjects (P < 0.05). T1ρ values of right patellar cartilage in athletes were also higher than healthy controls (P < 0.05). T1ρ values of patellar cartilage in both athletes and healthy subjects uncovered no apparent difference between the left knees and right knees (P > 0.05). Conclusion. T1ρ MRI could potentially represent a useful tool for the measurement of early articular cartilage degeneration in clinical practice.

T1ρ imaging as a non-invasive assessment of collagen remodelling and organization in human skeletal muscle after ligamentous injury.

Dysregulation and fibrosis of the extracellular matrix (ECM) in skeletal muscle is a consequence of injury. Current ECM assessment necessitates muscle biopsies to evaluate alterations to the muscle ECM, which is often not practical in humans. The goal of this study was to evaluate the potential of a magnetic resonance imaging sequence that quantifies T1ρ relaxation time to predict ECM collagen composition and organization. T1ρ imaging was performed and muscle biopsies obtained from the involved and non-involved vastus lateralis muscle on 27 subjects who had an anterior cruciate ligament (ACL) tear. T1ρ times were quantified via monoexponential decay curve fitted to a series of T1ρ-weighted images. Several ECM indices, including collagen content and organization, were obtained using immunohistochemistry and histochemistry in addition to hydroxyproline. Model selection with multiple linear regression was used to evaluate the relationships between T1ρ times and ECM composition. Additionally, the ACL-deficient and healthy limb were compared to determine sensitivity of T1ρ to detect early adaptations in the muscle ECM following injury. We show that T1ρ relaxation time was strongly associated with collagen unfolding (t=4.093, P=0.0007) in the ACL-deficient limb, and collagen 1 abundance in the healthy limb (t=2.75, P=0.014). In addition, we show that T1ρ relaxation time is significantly longer in the injured limb, coinciding with significant differences in several indices of collagen content and remodelling in the ACL-deficient limb. These results support the use of T1ρ to evaluate ECM composition in skeletal muscle in a non-invasive manner. KEY POINTS: Dysregulation and fibrotic transformation of the skeletal muscle extracellular matrix (ECM) is a common pathology associated with injury and ageing. Studies of the muscle ECM in humans have necessitated the use of biopsies, which are impractical in many settings. Non-invasive MRI T1ρ relaxation time was validated to predict ECM collagen composition and organization with aligned T1ρ imaging and biopsies of the vastus lateralis in the healthy limb and anterior cruciate ligament (ACL)-deficient limb of 27 subjects. T1ρ relaxation time was strongly associated with collagen abundance and unfolding in the ACL-deficient limb, and T1ρ relaxation time was strongly associated with total collagen abundance in the healthy limb. T1ρ relaxation time was significantly longer in the ACL-deficient limb, coinciding with significant increases in several indices of muscle collagen content and remodelling supporting the use of T1ρ to non-invasively evaluate ECM composition and pathology in skeletal muscle.

T1ρ and T2 MRI show hip cartilage damage in adolescents with healed Legg-Calvé-Perthes disease.

Legg-Calvé-Perthes disease (LCPD) is a juvenile hip disorder associated with residual femoral head deformity, cartilage degeneration and a high risk of early onset hip osteoarthritis. Assessing management of LCPD in the healed phase requires an understanding of when and where hip cartilage damage happens. While it has been shown that cartilage is degenerated in healed LCPD hips in adults, it is not clear when this degeneration begins. Our research question was: Are the MR markers of cartilage degeneration T1ρ and T2 increased in healed LCPD hips in adolescents? Twelve adolescents [10-17 years old (mean 14); 3 female 9 male] with healed LCPD (Stulberg 2-5; 8 unilateral and 4 bilateral) and 15 age- and sex-matched controls were imaged in a 3T MRI using a T1ρ and a T2 sequence. We applied a mixed-effects model adjusted for age and nested by subject to determine the effect of Stulberg grade on overall and regional mean T1ρ and T2 values. T1ρ was significantly higher overall and in the medial region of Stulberg ≥3 hips, and in the medial region of Stulberg 2 hips than in the control group. T2 was significantly higher in the medial region of Stulberg ≥3 hips than in the control group. Our results suggest that cartilage damage in LCPD has begun by adolescence and that T1ρ can detect early changes in cartilage associated with LCPD.

Quantitative T1ρ MRI of the Head and Neck Discriminates Carcinoma and Benign Hyperplasia in the Nasopharynx.

T1ρ imaging is a new quantitative MR imaging pulse sequence with the potential to discriminate between malignant and benign tissue. In this study, we evaluated the capability of T1ρ imaging to characterize tissue by applying T1ρ imaging to malignant and benign tissue in the nasopharynx and to normal tissue in the head and neck. Participants with undifferentiated nasopharyngeal carcinoma and benign hyperplasia of the nasopharynx prospectively underwent T1ρ imaging. T1ρ measurements obtained from the histogram analysis for nasopharyngeal carcinoma in 43 participants were compared with those for benign hyperplasia and for normal tissue (brain, muscle, and parotid glands) in 41 participants using the Mann-Whitney U test. The area under the curve of significant T1ρ measurements was calculated and compared using receiver operating characteristic analysis and the Delong test, respectively. A P < . 05 indicated statistical significance. There were significant differences in T1ρ measurements between nasopharyngeal carcinoma and benign hyperplasia and between nasopharyngeal carcinoma and normal tissue (all, P < . 05). Compared with benign hyperplasia, nasopharyngeal carcinoma showed a lower T1ρ mean (62.14 versus 65.45 × ms), SD (12.60 versus 17.73 × ms), and skewness (0.61 versus 0.76) (all P < .05), but no difference in kurtosis (P = . 18). The T1ρ SD showed the highest area under the curve of 0.95 compared with the T1ρ mean (area under the curve = 0.72) and T1ρ skewness (area under the curve = 0.72) for discriminating nasopharyngeal carcinoma and benign hyperplasia (all, P < .05). Quantitative T1ρ imaging has the potential to discriminate malignant from benign and normal tissue in the head and neck.

Subcortical T1-Rho MRI Abnormalities in Juvenile-Onset Huntington's Disease.

Huntington’s disease (HD) is a fatal neurodegenerative disease caused by the expansion of cytosine-adenine-guanine (CAG) repeats in the huntingtin gene. An increased CAG repeat length is associated with an earlier disease onset. About 5% of HD cases occur under the age of 21 years, which are classified as juvenile-onset Huntington’s disease (JOHD). Our study aims to measure subcortical metabolic abnormalities in JOHD participants. T1-Rho (T1ρ) MRI was used to compare brain regions of 13 JOHD participants and 39 controls. Region-of-interest analyses were used to assess differences in quantitative T1ρ relaxation times. We found that the mean relaxation times in the caudate (p < 0.001), putamen (p < 0.001), globus pallidus (p < 0.001), and thalamus (p < 0.001) were increased in JOHD participants compared to controls. Furthermore, increased T1ρ relaxation times in these areas were significantly associated with lower volumes amongst participants in the JOHD group. These findings suggest metabolic abnormalities in brain regions previously shown to degenerate in JOHD. We also analyzed the relationships between mean regional T1ρ relaxation times and Universal Huntington’s Disease Rating Scale (UHDRS) scores. UHDRS was used to evaluate participants’ motor function, cognitive function, behavior, and functional capacity. Mean T1ρ relaxation times in the caudate (p = 0.003), putamen (p = 0.005), globus pallidus (p = 0.009), and thalamus (p = 0.015) were directly proportional to the UHDRS score. This suggests that the T1ρ relaxation time may also predict HD-related motor deficits. Our findings suggest that subcortical metabolic abnormalities drive the unique hypokinetic symptoms in JOHD.

Zone- and layer-specific differences in proteoglycan content in patellofemoral pain syndrome are detectable on T1ρ MRI.

Determine if differences in T1ρ would be detected in specific regions or layers of patellofemoral cartilage between patients with symptomatic patellofemoral pain syndrome and asymptomatic control subjects. Ten subjects diagnosed with patellofemoral pain syndrome were compared with ten age-, gender-, and BMI-matched control subjects with no knee pain or prior trauma. Conventional turbo (fast) spin echo sequences and T1ρ-weighted imaging were performed on the symptomatic knee in each of the ten subjects. At the patella and distal femur, cartilage regions of interest were divided into medial and lateral sub-regions, each then further sub-divided by layer (superficial, middle, or deep). Two-tailed t test and chi-squared tests were used to analyze demographic data. A mixed effect model was run for each sub-region of T1ρ imaging. Statistical significance was determined using the likelihood ratio test against reduced models without patellofemoral pain syndrome symptomatic status as a fixed effect. There was no difference in age, sex, or BMI between symptomatic and control patients. T1ρ values were significantly higher among patellofemoral pain syndrome patients when compared with controls in the superficial zone of the lateral patella (58.43 vs. 50.83, p = 0.03) and the middle zone of the lateral patella (52.67 vs. 43.60, p = 0.03). T1ρ was also higher in the superficial zone of the medial femur (50.94 vs. 46.70, p = 0.09) with a value approaching statistical significance. We report statistically significant differences in the T1ρ value in the superficial and middlezones of the lateral patella in patients with patellofemoral pain syndrome who had no abnormalities seen on conventional MRI sequences, suggesting an alteration the macromolecular structure of the cartilage in this population.

Gadoxetic acid enhanced T1ρ and intravoxel incoherent motion MRI in quantitatively assessing the stages of nonalcoholic steatohepatitis

Objective To explore the values of metrics on intravoxel incoherent motion (IVIM) and gadoxetic acid enhanced T1ρ imaging for staging of non-alcoholic fatty liver disease activity scores (NAS) and inflammation in nonalcoholic steatohepatitis (NASH) rabbits model. Methods NASH rabbits model was established by feeding with a varied duration (4, 8, 12 weeks) of high-fat, high-cholesterol diet. IVIM and gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) enhanced T1ρ images were performed by a 3.0 T MR scanner. The inter-class correlation coefficients (ICC) and Bland-Altman analysis were applied to evaluate the reproducibility of the IVIM and Gd-EOB-DTPA enhanced T1ρ mapping measurers. Spearman correlation analysis were used to assess the correlation between MR metrics, including ADC, D, D*, f, T1ρ, T1ρ (hepatobiliary phase, HBP), and NAS score and inflammation grades respectively with reference to histopathology. ROC curve analysis was used to evaluate the diagnostic performance of T1ρ and IVIM parameters for NASH, inflammation grade, and hepatic fibrosis. Multiple linear regression equations were used to analyze the independent influence factors of T1ρ (HBP). Results The f value was negatively correlated with the NAS score (r=-0.530, P<0.01). The f value of the fibrosis S1-2 was significantly lower than that of the S0 (P<0.01). There was no statistical difference in D, D*, ADC among NASH score, inflammation, and fibrosis stage. T1ρ and T1ρ (HBP) values were positively correlated with NAS scores and inflammation grades. The area under curve (AUC) for the diagnosis of NASH for T1ρ, T1ρ(HBP), ADC, D, D*, and f values were 0.849, 0.949, 0.728, 0.596, 0.522, and 0.871, respectively. The AUCs of T1ρ (HBP)+f in the diagnosis of NASH, G2-3 inflammation, and F1-2 fibrosis were 0.971, 0.935, and 0.903, respectively. Fibrosis (R2=0.624, P=0.002) and inflammation (R2=0.746, P=0.002) were major independent factors of T1ρ (HBP). Conclusion Gd-EOB-DTPA enhanced T1ρ imaging can reflect the severity of NASH and degree of inflammation. IVIM measurements are not accurate enough to stage liver inflammatory activity of NASH. T1ρ (HBP)+f might be a superior noninvasive imaging biomarker than either non-enhanced T1ρ or IVIM for NASH activity and inflammation assessments. Key words: Magnetic resonance imaging; Nonalcoholic steatohepatitis; Intravoxel incoherent motion; Gadoxetate acid disodium

T1\u03c1-mapping for assessing knee joint cartilage in children with juvenile idiopathic arthritis \u2014 feasibility and repeatability

BackgroundOngoing arthritis in children with juvenile idiopathic arthritis (JIA) can result in cartilage damage.ObjectiveTo study the feasibility and repeatability of T1ρ for assessing knee cartilage in JIA and also to describe T1ρ values and study correlation between T1ρ and conventional MRI scores for disease activity.Materials and methodsThirteen children with JIA or suspected JIA underwent 3-tesla (T) knee MRI that included conventional sequences and a T1ρ sequence. Segmentation of knee cartilage was carried out on T1ρ images. We used intraclass correlation coefficient to study the repeatability of segmentation in a subset of five children. We used the juvenile arthritis MRI scoring system to discriminate inflamed from non-inflamed knees. The Mann-Whitney U and Spearman correlation compared T1ρ between children with and without arthritis on MRI and correlated T1ρ with the juvenile arthritis MRI score.ResultsAll children successfully completed the MRI examination. No images were excluded because of poor quality. Repeatability of T1ρ measurement had an intraclass correlation coefficient (ICC) of 0.99 (P<0.001). We observed no structural cartilage damage and found no differences in T1ρ between children with (n=7) and without (n=6) inflamed knees (37.8 ms vs. 31.7 ms, P=0.20). However, we observed a moderate correlation between T1ρ values and the juvenile arthritis MRI synovitis score (r=0.59, P=0.04).ConclusionThis pilot study suggests that T1ρ is a feasible and repeatable quantitative imaging technique in children. T1ρ values were associated with the juvenile arthritis MRI synovitis score.

Does Cartilage Degenerate in Asymptomatic Hips With Cam Morphology?

The management of asymptomatic individuals with cam femoral morphology that predisposes their hips to femoroacetabular impingement has received little attention. Such hips may have subclinical articular damage; however, whether this cartilage damage will progress is unknown as is whether any particular bone morphologies are associated with this progression. Such knowledge could help determine the natural history and guide management of such individuals. The purpose of this study was to determine whether (1) asymptomatic hips with cam morphology are at risk of further cartilage degeneration (as evaluated by T1ρ); (2) T1ρ changes are predictive of symptom onset; and (3) bony morphologic parameters are associated with T1ρ signal changes. In a prospective, longitudinal study, 17 asymptomatic volunteers/hips (16 men; 33 ± 6 years) with cam morphology underwent two T1ρ MRI scans and functional assessment (WOMAC) at recruitment and at 4 years (range, 2-6 years). Volunteers were recruited from a previous study, which reported on the prevalence of cam morphology among asymptomatic individuals using hip MRI; cam morphology was defined as an α angle ≥ 60° anterolaterally and/or ≥ 50.5° anteriorly relative to the neck axis. The differences in T1ρ values (ΔT1ρ) and relative differences (%ΔT1ρ) were calculated as: ΔT1ρ = T1ρFollowup - T1ρInitial and %ΔT1ρ = ΔT1ρ/T1ρInitial. A %ΔT1ρ > 17.6% was considered clinically important. Using CT data, femoral, acetabular, and spinopelvic parameters were measured. Whether ΔT1ρ and/or %ΔT1ρ was associated with any of the bone morphologic parameters was tested using Spearman's correlation coefficient. The global T1ρ in these asymptomatic hips with cam morphology remained unchanged between initial (mean, 35 ± 5 ms) and followup scans (mean, 34 ± 3 ms; p = 0.518). No differences with the numbers available in T1ρ values were seen initially between the anterolateral and posterolateral (34 ± 6 ms versus 33 ± 4 ms; p = 0.734) regions; at followup, T1 values were higher posterolaterally (36 ± 5 ms versus 32 ± 5 ms; p = 0.031). The mean global ΔT1ρ was 1 ± 5 ms (95% confidence interval, -1 to +3 ms) and the mean global %ΔT1ρ was 2% ± 13%. Two volunteers reported lower WOMAC scores; one patient exhibited a clinically important increase in %ΔT1ρ (-26%). The degree of acetabular coverage correlated with %ΔT1ρ (rho = 0.59-0.61, p = 0.002); the lesser the acetabular coverage anterolaterally, the greater the corresponding area's T1ρ at followup. Although signs of posterolateral joint degeneration were detected, these were not generally associated with symptoms, and only one of the two volunteers with the onset of symptoms had a clinically important increase in %ΔT1ρ. We found that reduced acetabular coverage may increase the likelihood that preclinical cartilage degeneration will arise within 2 to 6 years; thereby reduced acetabular coverage should be considered when stratifying asymptomatic hips at risk of degeneration. Future studies should be performed with a larger cohort and include femoral version among the parameters studied. Level II, diagnostic study.

T1ρ MRI of the talar articular cartilage is increased in those with chronic ankle instability

To determine if individuals with chronic ankle instability (CAI) demonstrate different talar cartilage T1ρ relaxation times compared to uninjured controls. Fifteen CAI (21.13±1.81 years, 4.00±2.07 previous ankle sprains) and fifteen controls (21.07±2.55 years, no previous ankle sprains) participated. CAI inclusion criteria was in accordance with the International Ankle Consortium guidelines. Greater T1ρ relaxation times were interpreted as greater degenerative changes. Participants were non-weight bearing for 30-minutes prior to scanning to unload the cartilage. Voxel by voxel T1ρ relaxation times were calculated from a five image sequence. Segmentation of the talar cartilage was performed manually using ITK-SNAP software. T1ρ relaxation time means and variability across the entire talus and in the anteromeidal, anterolateral, posteromedial, and posterolateral regions of interest (ROIs) were compared between groups using mean differences and effect sizes (ES) with their corresponding 95% confidence intervals (95%CI). Individuals with CAI demonstrated higher T1ρ relaxation times (mean±standard deviation) across the entire talus (CAI: 65.97±10.45ms, Control: 58.84±7.68ms; ES=0.76, 95%CI=0.02-1.50), in the anterolateral (ES=1.00, 95%CI=0.24-1.48), posteromedial (ES=0.74, 95%CI=0.01-1.49), and posterolateral region of interest (ES=3.84, 95%CI=2.63-5.04). The T1ρ relaxation time variability (mean±standard deviation) also differed across the overall talus (CAI: 32.78±4.06ms, Control: 28.23±4.45ms; ES=1.04, 95%CI=0.28-1.80), in the anteriolateral, (ES=1.07, 95%CI=0.31, 1.84) and posteriolateral (ES=1.00, 95%CI=0.24-1.75) ROIs. Individuals with CAI demonstrate greater T1ρ relaxation times and higher T1ρ variability compared to uninjured controls. This finding supports the existing literature illustrating early degenerative joint tissue changes consistent with early onset posttraumatic osteoarthritis in individuals with CAI.

Longitudinal analysis of tibiofemoral cartilage contact area and position in ACL reconstructed patients

Patients who have suffered ACL injury are more likely to develop early onset post-traumatic osteoarthritis despite reconstruction. The purpose of our study was to evaluate the longitudinal changes in the tibiofemoral cartilage contact area size and location after ACL injury and reconstruction. Thirty-one patients with isolated unilateral ACL injury were followed with T2 weighted Fast Spin Echo, T1ρ and T2 MRI at baseline prior to reconstruction, and 6 months, 1 year, and 2 years after surgery. Areas were delineated in FSE images with an in-house Matlab program using a spline-based semi-automated segmentation algorithm. Tibiofemoral contact area and centroid position along the anterior-posterior axis were calculated along with T1ρ and T2 relaxation times on both the injured and non-injured knees. At baseline, the injured knees had significantly smaller and more posteriorly positioned contact areas on the medial tibial surface compared to corresponding healthy knees. These differences persisted 6 months after reconstruction. Moreover, subjects with more anterior medial centroid positions at 6 months had elevated T1ρ and T2 measures in the posterior medial tibial plateau at 1 year. Changes in contact area and centroid position after ACL injury and reconstruction may characterize some of the mechanical factors contributing to post-traumatic osteoarthritis. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2718-2727, 2018.

Proteoglycan density of the talar articular cartilage is reduced in those with chronic ankle instability

Purpose: Clear links have been made between both lateral ankle sprains and chronic ankle instability (CAI) and the development of ankle post-traumatic osteoarthritis (PTOA). Current visualization techniques such as arthroscopy and standard MRI are ineffective at quantifying early degenerative changes to the talar articular cartilage. The most promising approaches for slowing ankle PTOA progression include early conservative interventions to restore appropriate joint biomechanics. Thus, identifying visualization techniques sensitive to early degenerative changes of the talar articular cartilage is needed. Therefore, the purpose of this investigation is to determine if CAI patients have lower proteoglycan density in their talar cartilage compared to uninjured controls as measured by T1ρ MRI. Methods: Fifteen CAI (age: 21.2 ± 1.8 years, height: 1.7 ± .8 m, mass: 67.0 ± 7.7 kg) and fifteen controls (age: 21.0 ± 2.5 years, height: 1.7 ± .8 m, weight: 69.6 ± 13.2 kg) volunteered to participate. CAI inclusion criteria were in accordance with the International Ankle Consortium guidelines. Relative to the controls, CAI participants had a history of multiple lateral ankle sprains (4.0 ± 2.1 vs. 0.0 ± 0.0 sprains), multiple giving way episodes within the past 6 months (6.6 ± 5.1 vs. 0.0 ± 0.0 episodes), higher Identification of Functional Ankle Instability scores (22.9 ± 2.8 vs. 0.1 ± 0.5), and greater limitations in self-reported function based on the Foot and Ankle Ability Measure (85.9 ± 9.7% vs. 100.0 ± 0.0%) and Foot and Ankle Ability Measure Sport (68.4 ± 20.6% vs. 100.0 ± 0.0%). Proteoglycan density was assessed using T1ρ MRI with greater T1ρ relaxation times interpreted as reduced proteoglycan density. A Siemens Magnetom TIM Trio 3T scanner and an 8-channel flex coil in conjunction with three-dimensional Fast Low Angle Shot (FLASH) with a spin lock power at 500 Hz, five different spin lock durations (40, 30, 20,10, 0 ms) was used to acquire the T1ρ MRI. Participants were non-weight bearing for 30 minutes prior to the scan to unload the cartilage. Voxel by voxel T1rho relaxation times were calculated from a five image sequence created with a MatLab program. Segmentation of the T1ρ talar cartilage was performed manually using ITK-SNAP software. Four regions of interest: anteromeidal, anterolateral, posteromedial, and posterolateral were identified during segmentation. Mean T1ρ relaxation times in each region of interest were compared between CAI patients and healthy controls using independent sample t-tests and an a priori alpha level of 0.05. Results: The CAI and controls groups were similar in terms of their age, height, and mass (P ≥ 0.433). Measures of injury history and self-reported function differed between the groups (P < 0.001) as expected. CAI patients had significantly higher T1ρ relaxation times in three of the four regions of interest including the anterolateral region (CAI: 66.57 ± 11.42 ms, Control: 57.73 ± 5.91 ms, P = 0.013), posteromedial region (CAI: 63.48 ± 12.43 ms, Control: 54.71 ± 10.84 ms, P = 0.049), and posterolateral region (CAI: 65.97 ± 11.75 ms, Control: 54.20 ± 10.03 ms, P = 0.006). No differences were noted in the anteromedial region (CAI: 67.61 ± 13.30 ms, Control: 60.91 ± 13.65 ms, P = 0.184). Conclusions: CAI patients showed higher T1ρ relaxation times compared to controls in three of the four regions of interest suggesting reduced proteoglycan density in the talar cartilage. This finding supports the existing arthroscopic literature that illustrates early degenerative changes in CAI patients. Further research is needed to determine the underlying mechanisms of these degenerative changes and to identify therapeutic interventions capable of slowing the progression of these degenerative changes following lateral ankle sprains and CAI.

Advance of MRI T1ρ in evaluation of liver fibrosis

Chronic liver disease (CLD) is one of the major public health problems, and liver fibrosis is a common feature of CLD. To date, there is no noninvasive method with high sensitivity and specificity for diagnosing and monitoring liver fibrosis in clinical practice. MRI T1ρ, a new technology developed in recent years, is sensitive to macromolecular (such as protein) composition and proton exchange between water and macromolecules, and therefore may be sensitive for the evaluation of liver fibrosis. This review introduces the principle and state of the art of liver MRI T1ρ technology, and summarizes the applications of MRI T1ρ for evaluation of liver fibrosis. Key words: Liver cirrhosis; Magnetic resonance imaging; Trends

Bone morphological factors influencing cartilage degeneration in the knee

Objectives: Morphological features of the distal femur and proximal tibia associated with cartilage degeneration are unknown. This study aimed to elucidate local anatomical parameters of the knee which correlate with articular cartilage degeneration using MRI T1ρ mapping.Methods: This study involved 200 subjects with knee pain (mean age, 48.7 years; range, 14–80 years) with no severe osteoarthritic changes on plain X-ray. T1ρ values were measured in the regions of interest on the surface layer of the cartilage on mid-coronal images of the femorotibial joint. Assessment of medial and lateral posterior tibial slope (MTS, LTS) and medial and lateral femoral condylar offset ratio (MFCOR, LFCOR) was performed using sagittal proton density-weighted imaging. Morphological assessment of posterior root and horn of menisci was also performed according to a modified Whole Organ Magnetic Resonance Imaging Score (WORMS) of the knee.Results: Multiple regression analysis revealed that a decrease in MTS was associated with increased T1ρ values in the medial tibia, independent of age, osteoarthritic changes on plain X-ray, femur-tibia angle (FTA), and posterior medial meniscal lesions.Conclusions: Shallow MTS correlates with cartilage degeneration in symptomatic patients. This parameter could help in understanding the etiology of osteoarthritis in the early stage. Future kinematic studies will be needed to confirm our findings.

3D Correlation Mapping between Changes in Cartilage T1ρ and Thickness Over 1-year after ACL Reconstruction using Atlas-based Methods

Purpose: Subjects with anterior cruciate ligament (ACL) injury are at risk for post-traumatic osteoarthritis (PTOA). T1ρ MRI has been used to detect early degeneration after ACL injury and reconstruction. Previous studies also revealed significant changes in cartilage thickness after ACL injury, with thickness increasing in some compartments while decreasing in other compartments. However, the correlation between the change in T1ρ and the change in cartilage thickness has not been demonstrated. A better understanding of these correlations will help with staging the cartilage degeneration status after ACL injury. Very recently, a novel atlas-based method was developed which permits voxel-based relaxometry analysis (VBR). The goal of this study was to apply the atlas-based method to evaluate the local voxel-by-voxel correlation between changes in T1ρ and changes in thickness from baseline to 6-months and 1-year after ACL reconstruction (ACLR). Methods: Bilateral knees were scanned using a 3T MRI scanner for twenty-five patients with ACL injuries prior to surgical reconstruction (baseline, BL), and 6-months (6M) and 1-year (1Y) after ACLR (age = 28.4 ± 8.2 years, BMI = 23.8± 2.7 kg/m2, 10 female). The imaging protocol included the 3D MAPSS T1ρ/T2 sequence used for cartilage relaxation times quantification and high-resolution 3D FSE (CUBE) used for WORMS grading and semi-automatic cartilage segmentation. Those segmentations were used to define a voxel based thickness map for each subject. An atlas based registration approach was then used to morph all the T1ρ-weighted images and the thickness maps to the same reference space, and T1ρ maps were computed in the atlas space allowing for voxel-by-voxel correspondence between T1ρ and thickness. Longitudinal changes in cartilage thickness and T1ρ, as well as the local Pearson correlation coefficients between changes in T1ρ and changes in thickness were calculated voxel-by-voxel. Both analyses were adjusted for age, gender and BMI. The level of significance was set at p<0.05. Percentage of significant voxel (PSV, %) with positive or negative correlation and the mean value of correlation coefficients (R) were calculated in each compartment. Results: Significant increases of T1ρ in MFC and trochlea, and significant decreases of T1ρ in patella were observed; while significant increases of cartilage thickness in patella and significant decreases of cartilage thickness in trochlea were observed (Fig. 1 A–B). The most significant correlation between changes in T1ρ and changes in thickness was observed in patella, LFC, trochlea and MFC (Fig. 1C). In the patella, significant negative correlation was found between changes in T1ρ and changes in thickness from BL to 6M (38.4% voxels, R=−0.536) and from BL to 1Y (15.1% voxels, R=−0.590) (Tab1). This correlation was primarily the result of a decrease in T1ρ and an increase in thickness, while in other compartments, the negative correlations primarily resulted from an increase in T1ρ and a decrease in thickness. From 6M to 1Y, in LFC, a large decrease of the positive correlation PSV (from 11.2% to 2.5%) and a slight increase of negative correlation PSV were observed. There is an increasing trend of the total cartilage WORMS scores from BL (2.0±2.1) to 6M (2.2±2.1) and 1Y (2.4±2.3), but the increase was not significant. Conclusions: In this study, the local correlation between changes in cartilage matrix composition and changes in cartilage thickness was analyzed voxel-by-voxel using a novel 3D atlas-based method. Significant correlations were observed between ΔT1ρ and ΔΤhickness from BL to 6M and 1Y after ACLR. A positive correlation with increase in T1ρ and thickness may suggest the cartilage is at very early stages of degeneration with tissue swelling; while a negative correlation with increase in T1ρ and decrease in thickness may suggest later stages that cartilage begins to experience tissue loss. From 6M to 1Y, there is a general trend of decreasing positive correlation percentage while an increasing negative correlation percentage (Figure 2) in the femoral condyles and trochlea, suggests a progression of cartilage degeneration, confirmed by change in WORMS. In patella, the negative correlation was driven by the decrease of T1ρ and increase of thickness, which may be associated with changes in loading to patella-femoral joint (PFJ) as well as changes in activities after ACLR. Longer follow-up analysis is warranted to better understand cartilage degeneration progression after ACL injury. Funding from NIH/NIAMS P50 AR060752.

T1ρ Mri Assessment of Cartilage in a Large Animal Model of Traumatic Joint Injury

T1ρ Mri Assessment of Cartilage in a Large Animal Model of Traumatic Joint Injury

T1ρ Hip Cartilage Mapping in Assessing Patients With Cam Morphology: How Can We Optimize the Regions of Interest?

T1ρ MRI has been shown feasible to detect the biochemical status of hip cartilage, but various region-of-interest strategies have been used, compromising the reproducibility and comparability between different institutions and studies. The purposes of this study were (1) to determine representative regions of interest (ROIs) for cartilage T1ρ mapping in hips with a cam deformity; and (2) to assess intra- and interobserver reliability for cartilage T1ρ mapping in hips with a cam deformity. The local ethics committee approved this prospective study with written informed consent obtained. Between 2010 and 2013, in 54 hips (54 patients), T1ρ 1.5-T MRI was performed. Thirty-eight hips (38 patients; 89% male) with an average age of 35 ± 7.5 years (range, 23-51 tears) were diagnosed with a cam deformity; 16 hips (16 patients; 87% male) with an average age of 34 ± 7 years (range, 23-47 years) were included in the control group. Of the 38 patients with a cam deformity, 20 were pain-free and 18 symptomatic patients underwent surgery after 6 months of failed nonsurgical management of antiinflammatories and physical therapy. Exclusion criteria were radiologic sings of osteoarthritis with Tönnis Grade 2 or higher as well as previous hip surgery. Three region-of-interest (ROI) selections were analyzed: Method 1: as a whole; Method 2: as 36 to 54 small ROIs (sections of 30° in the sagittal plane and 3 mm in the transverse plane); Method 3a: as six ROIs (sections of 90° in the sagittal plane and one-third of the acetabular depth in the transverse plane: the anterosuperior and posterosuperior quadrants, divided into lateral, intermediate, and medial thirds); and Method 3b: as the ratio (anterosuperior over posterosuperior quadrant). ROIs in Method 3 represent the region of macroscopic cartilage damage, described in intraoperative findings. To asses interobserver reliability, 10 patients were analyzed by two observers (HA, GM). For intraobserver reliability, 20 hip MRIs were analyzed twice by one observer (HA). To assess interscan reliability, three patients underwent two scans within a time period of 2 weeks and were analyzed twice by one observer (HA). T1ρ values were compared using Student's t test. Interclass correlation coefficient (ICC) and root mean square coefficient of variation (RMS-CV) were used to analyze intraobserver, interobserver, and interscan reliability. Patients with a cam deformity showed increased T1ρ values in the whole hip cartilage (mean: 34.0 ± 3.8 ms versus 31.4 ± 3.0 ms; mean difference: 2.5; 95% confidence interval [CI], 4.7-0.4; p = 0.019; Method 1), mainly anterolateral (2), in the lateral and medial thirds of the anterosuperior quadrant (mean: 32.3 ± 4.9 ms versus 29.4 ± 4.1 ms; mean difference: 3.0; 95% CI, 5.8-0.2; p = 0.039 and mean 36.5 ± 5.6 ms versus 32.6 ± 3.8 ms; mean difference: 3.8; 95% CI, 6.9-0.8; p = 0.014), and in the medial third of the posterosuperior quadrant (mean: 34.4 ± 5.5 ms versus 31.1 ± 3.9 ms; mean difference: 3.1; 95% CI, 6.2-0.1; p = 0.039) (3a). The ratio was increased in the lateral third (mean: 1.00 ± 0.12 versus 0.90 ± 0.15; mean difference: 0.10; 95% CI, 0.18-0.2; p = 0.018) (3b). ICC and RMS-CV were 0.965 and 4% (intraobserver), 0.953 and 4% (interobserver), and 0.988 (all p < 0.001) and 9% (inter-MR scan), respectively. Cartilage T1ρ MRI mapping in hips is feasible at 1.5 T with strong inter-, intraobserver, and inter-MR scan reliability. The six ROIs (Method 3) showed a difference of T1ρ values anterolateralquadrant, consistent with the dominant area of cartilage injury in cam femoroacetabular impingement, and antero- and posteromedial, indicating involvement of the entire hip cartilage health. The six ROIs (Method 3) have been shown feasible to assess cartilage damage in hips with a cam deformity using T1ρ MRI. We suggest applying this ROI selection for further studies using quantitative MRI for assessment of cartilage damage in hips with a cam deformity to achieve better comparability and reproducibility between different studies. The application of this ROI selection on hips with other deformities (eg, pincer deformity, developmental dysplasia of the hip, and acetabular retroversion) has to be analyzed and potentially adapted. Level III, diagnostic study.