Resonance Imaging T2 Relaxation Time Research Articles

Magnetic Resonance Imaging T2 Relaxation Times of Articular Cartilage Before and After Arthroscopic Surgery for Discoid Lateral Meniscus

To quantitatively evaluate degeneration of articular cartilage using magnetic resonance imaging (MRI) T2 mapping before and after arthroscopic surgery for discoid lateral meniscus (DLM). We retrospectively reviewed the medical records of patients who underwent arthroscopic reshaping surgery for symptomatic DLM from September 2013 to October 2017 and who had undergone follow-up for ≥2 years. MRI T2 relaxation examinations had been performed preoperatively and at 3, 6, 12, and 24 months postoperatively. The T2 relaxation times of the whole lateral femoral condyle and the tibial plateau were assessed. In addition, the lateral femoral condyle was divided into 3 subcompartmental areas: anterior, middle, and posterior. In total, 30 knees of 27 patients were included in this study. The patients' mean age at operation was 13.3 years (range 6-23 years), and the mean follow-up period was 31.6 months. Saucerization alone was performed in 3 knees and saucerization with repair in 27 knees. The T2 relaxation time of the whole lateral femoral condyle was significantly increased at 3 and 6 months postoperatively and significantly decreased at 12 and 24 months. The T2 relaxation time of the whole lateral tibial plateau was significantly increased at 3 months postoperatively and significantly decreased at 24 months. The T2 relaxation time of the posterior subcompartment of the lateral femoral condyle was significantly increased at 3 months and significantly decreased at 12 and 24 months. The T2 relaxation time of the lateral femorotibial joint cartilage increased at 3 and 6 months postoperatively and then had decreased at 12 and 24 months. Quantitative MRI allowed us to monitor the substantial changes in the cartilage during the early postoperative period and the recovery at the distant time point after reshaping surgery for DLM. Level IV, case series.

Biochemical changes in knee articular cartilage of novice half-marathon runners.

ObjectiveTo evaluate changes in knee articular cartilage of novice half-marathon runners using magnetic resonance imaging T2 relaxation time mapping.MethodsHealthy subjects were recruited from local running clubs who met the following inclusion criteria: (i) age 18–45 years; (ii) body mass index less than 30 kg/m2; (iii) had participated in one half-marathon or less (none within the previous 6 months); (iv) run less than 20 km/week; (v) no previous knee injury or surgery; (vi) no knee pain. T2 signals were measured pre- and post-race to evaluate the biochemical changes in articular cartilage after the subjects run a half-marathon.ResultsA significant increase in the mean ± SD T2 relaxation time was seen in the outer region of the medial tibial plateau (50.1 ± 2.4 versus 54.7 ± 2.6) and there was a significant decrease in T2 relaxation time in the lateral femoral condyle central region (50.2 ± 4.5 versus 45.4 ± 2.9). There were no significant changes in the patella, medial femoral condyle and lateral tibia articular surfaces.ConclusionAn increase in T2 relaxation time occurs in the medial tibial plateau of novice half-marathon runners. This limited region of increased T2 values, when compared with complete medial compartment involvement seen in studies of marathon runners, may represent an association between distance run and changes seen in articular cartilage T2 values.

Lithium suppression of tau induces brain iron accumulation and neurodegeneration.

Lithium is a first-line therapy for bipolar affective disorder. However, various adverse effects, including a Parkinson-like hand tremor, often limit its use. The understanding of the neurobiological basis of these side effects is still very limited. Nigral iron elevation is also a feature of Parkinsonian degeneration that may be related to soluble tau reduction. We found that magnetic resonance imaging T2 relaxation time changes in subjects commenced on lithium therapy were consistent with iron elevation. In mice, lithium treatment lowers brain tau levels and increases nigral and cortical iron elevation that is closely associated with neurodegeneration, cognitive loss and parkinsonian features. In neuronal cultures lithium attenuates iron efflux by lowering tau protein that traffics amyloid precursor protein to facilitate iron efflux. Thus, tau- and amyloid protein precursor-knockout mice were protected against lithium-induced iron elevation and neurotoxicity. These findings challenge the appropriateness of lithium as a potential treatment for disorders where brain iron is elevated (for example, Alzheimer's disease), and may explain lithium-associated motor symptoms in susceptible patients.

Cartilage status in knees with recurrent patellar instability using magnetic resonance imaging T2 relaxation time value.

The purpose of the study was to analyse the patellar status in patients with recurrent patellar instability and in healthy controls using magnetic resonance imaging (MRI). One hundred and thirteen patients with patellar instability (patellar instability group) and 50 healthy controls (control group) were studied. All patients underwent computed tomography (CT) to measure the patellofemoral joint anatomy. Meanwhile, MRI was used to investigate cartilage status and to determine the T2 relaxation time value of the patellar cartilage plate. The mean values of these parameters for the patellar instability group and the control group were compared. The CT images of the patellar instability group revealed greatly abnormal anatomy of the patellofemoral joint compared with the control group. By MRI assessment, 32 patients were determined to have a cartilage defect, which was confirmed under arthroscopy. Among the other 81 patients, the T2 relaxation time value of the patellar instability group was significantly higher than that of the control group on the middle (p=0.032) or medial sites (p=0.041) of the patellar cartilage. The patellar instability group exhibits a higher risk of cartilage lesions with abnormal patellofemoral joint anatomy. MRI may enable early detection of these cartilage defects within the patellofemoral joint, enabling clinicians to adopt strategies to delay or prevent cartilage degeneration. III.

In vivo magnetic resonance imaging characterization of bilateral structural changes in experimental Parkinson’s disease: a T2 relaxometry study combined with longitudinal diffusion tensor imaging and manganese-enhanced magnetic resonance imaging in the 6-

The neuropathological hallmark of Parkinson's disease is the loss of dopaminergic neurons in the pars compacta of the substantia nigra (SNc). The degenerative process starts unilaterally and spreads to the dopaminergic system of both hemispheres. However, the complete characterization of the nigra lesion and the subsequent changes in basal ganglia nuclei activity has not yet been achieved in vivo. The aim of this study was to characterize the time course of the nigral lesion in vivo, using longitudinal T2 relaxometry and diffusion tensor imaging, and the changes in basal ganglia nuclei activity, using manganese-enhanced magnetic resonance imaging, in 6-hydroxydopamine (6-OHDA)-lesioned rats. Our results showed that a unilateral SNc lesion induces bilateral alterations, as indicated by the enhancement of magnetic resonance imaging T2 relaxation times in both the ipsilateral and contralateral SNc. Moreover, axial and radial diffusivities demonstrated bilateral changes at 3 and 14 days after 6-OHDA injection in the pars reticulata of the substantia nigra and cortex, respectively, in comparison to the sham group, suggesting bilateral microstructural alterations in these regions. Unexpectedly, manganese-enhanced magnetic resonance imaging showed decreased axonal transport from the ipsilateral subthalamic nucleus to the ventral pallidum in 6-OHDA-lesioned animals compared with the sham group. These findings demonstrate, for the first time in vivo, the temporal pattern of bilateral alteration induced by the 6-OHDA model of Parkinson's disease, and indicate decreased axonal transport in the ipsilateral hemisphere.

Pediatric clinical research

This review will focus on childhood-onset systemic lupus erythematosus, juvenile idiopathic arthritis, and juvenile dermatomyositis, with special interest on strategies to improve the health-related quality of life in these conditions. The contribution of plasma insulin levels, lipoproteins, markers of oxidized state (including nitric oxide metabolites, isoprostanes) and autoantibodies to oxidized low-density lipoprotein to risk for atherosclerosis has been studied in childhood-onset systemic lupus erythematosus. Elevated serum levels of myeloid-related protein-8 (also called S100A8) and myeloid-related protein-14 (S100A9) in children with juvenile idiopathic arthritis can indicate clinically occult disease activity. Serum levels of S100A12 correlate with disease activity in juvenile idiopathic arthritis. Magnetic resonance imaging T2 relaxation times in weight-bearing cartilage in patients with juvenile idiopathic arthritis may help with early detection of cartilage changes. Quantitative computed tomography commonly shows decreased muscle mass and abnormal bone geometry in juvenile idiopathic arthritis patients. In patients with juvenile idiopathic arthritis who do not respond to oral methotrexate, subcutaneous methotrexate dosing was frequently successful. Duration of inactive disease while a patient is receiving methotrexate does not decrease the frequency of flaring of disease once methotrexate is discontinued. Residual synovial inflammation seems to be a stronger influence on the rate of relapse. In juvenile dermatomyositis, the quantitative magnetic resonance imaging T2 relaxation time and overexpression of Class I major histocompatibility complex in early juvenile dermatomyositis are reported. Intravenous cyclophosphamide in refractory juvenile dermatomyositis and tacrolimus ointment for the dermatologic manifestations of juvenile dermatomyositis seem promising. Progress has been made in the diagnosis and treatment of childhood-onset systemic lupus erythematosus, juvenile idiopathic arthritis, and juvenile dermatomyositis.

Age dependency of cartilage magnetic resonance imaging T2 relaxation times in asymptomatic women.

Because the magnetic resonance imaging (MRI) transverse relaxation time (T2) of cartilage is sensitive to organization of collagen fibers in the cartilage, it may be a noninvasive image marker for senescent changes in cartilage collagen and early cartilage degeneration. The purpose of this study was to determine age-dependent differences in cartilage T2 values in healthy asymptomatic women. Quantitative T2 maps of patellar cartilage from 30 asymptomatic women ages 22-86 years were obtained using a 3.0T MRI scanner. The study population was stratified by age into 4 cohorts: 18-30, 31-45, 46-65, and 66-86 years. Spatial differences in cartilage T2 were determined as a function of normalized distance from bone. Older groups were compared with the 18-30-year-old group to determine the effects of age on cartilage T2 values. Regions were considered statistically significantly different if the mean T2 values between groups differed at P < 0.05. Mean cartilage T2 profiles were nearly identical for the 2 youngest cohorts. Compared with the 18-30-year-old group, T2 values were statistically significantly longer in the superficial 40% of cartilage in the 46-65-year-old group and over the entire cartilage thickness in the 66-86-year-old group. The location of T2 elevations in women over the age of 45 years is consistent with the theory that senescent changes of cartilage collagen begin near the articular surface and progress to the deeper cartilage with advancing age.

The Most Effective Exercise for Strengthening the Supraspinatus Muscle

Electromyography has been used to determine the best exercise for strengthening the supraspinatus muscle, but conflicting results have been reported. Magnetic resonance imaging T2 relaxation time appears to be more accurate in determining muscle activation. To determine the best exercises for strengthening the supraspinatus muscle. Criterion standard. Six male volunteers performed three exercises: the empty can, the full can, and horizontal abduction. Immediately before and after each exercise, magnetic resonance imaging examinations were performed and changes in relaxation time for the subscapularis, supraspinatus, infraspinatus, teres minor, and deltoid muscles were recorded. The supraspinatus muscle had the greatest change among the studied muscles in relaxation time for the empty can (10.5 ms) and full can (10.5 ms) exercises. After the horizontal abduction exercise the change in relaxation time for the supraspinatus muscle (3.6 ms) was significantly smaller than that for the posterior deltoid muscle (11.5 ms) and not significantly different from that of the other muscles studied. The empty can and full can exercises were most effective in activating the supraspinatus muscle.