Increase In T2 Values Research Articles

Characteristics of distal femoral articular cartilage in 6 weeks posttraumatic osteoarthritis by a subcritical impact.

Traumatized knee greatly contributes to osteoarthritis (OA) of the knee in young adults. To intervene effectively before the onset of severe structural disruption, detection of the disease at the early onset is crucial. In this study, we put together the findings for the detection of OA from the femoral knee joint cartilage of the rabbit at 6 weeks posttrauma. Articular cartilage samples are taken from the impacted and nonimpacted joints at 0 week (serving as the control group) and at 6 weeks posttrauma by minimal force. The samples were imaged using microscopic magnetic resonance imaging (µMRI) at 11.7 µm/pixel and polarized light microscopy (PLM) at 1 µm/pixel. In addition, an inductively coupled plasma - optical emission spectrometry analysis was performed using the adjacent cartilage samples. The outcomes of this study demonstrate an increase in T2 values in 6 weeks samples compared to the 0 week samples by µMRI technique, indicating a general increase of tissue hydration within cartilage. PLM detects a decrease in the average thickness of the superficial zones in the posttraumatic osteoarthritis samples, significant in the impacted femurs. There was an average increasing trend of maximum retardation in the tide mark in comparison to the reported calcium concentration (mg/L) in impacted samples suggesting a possible rise in mineralization in the 6 weeks samples. Qualitatively, physical observation of the joint after 6 weeks showed signs of reddening in the anterior femur suggesting the disease process is a localized phenomenon. Through microscopic imaging, we are able to detect these changes at 6 weeks posttrauma qualitatively and quantitatively.

Performance of the prospective T2 MRI biomarker of neurotoxicity in a trimethyltin model in rats at 7 T

The assessment of the sensitivity and specificity of any potential biomarker against the gold standard is an important step in the process of its qualification by regulatory authorities. Such qualification is an important step towards incorporating the biomarker into the panel of tools available for drug development. In the current study we analyzed the sensitivity and specificity of T2 MRI relaxometry to detect trimethyltin-induced neurotoxicity in rats. Seventy-five male Sprague-Dawley rats were injected with a single intraperitoneal dose of either TMT (8, 10, 11, or 12 mg/kg) or saline (2 ml/kg) and imaged with 7 T MRI before and 3, 7, 14, and 21 days after injection using a quantitative T2 mapping. Neurohistopathology (the gold standard in the case of neurotoxicity) was performed at the end of the observation and used as an outcome qualifier in receiver-operator characteristic (ROC) curve analysis of T2 changes as a predictor of neurotoxicity. TMT treatment led to a significant increase in T2 values in many brain areas. The biggest changes in T2 values were seen around the lateral ventricles, which was interpreted as ventricular dilation. The area under the ROC curve for the volume of the lateral ventricles was 0.878 with the optimal sensitivity/specificity of 0.805/0.933, respectively. T2 MRI is a promising method for generating a non-invasive biomarkers of neurotoxicity, which shows the dose-response behavior with substantial sensitivity and specificity. While its performance was strong in the TMT model, further characterization of the sensitivity and specificity of T2 MRI with other neurotoxicants is warranted.

T2 Mapping of Patellar Cartilage After a Single First-Time Episode of Traumatic Lateral Patellar Dislocation.

In most cases, lateral patellar dislocation (LPD) is accompanied by chondral injury and may initiate gradual degeneration of patellar cartilage, which might be detected with a T2 mapping, a well-established method for cartilage lesions assessment. To examine short-term consequences of single first-time LPD in teenagers by T2 mapping of the patellar-cartilage state. Prospective. 95 patients (mean age: 15.1 ± 2.3; male/female: 46/49) with first-time, complete, traumatic LPD and 51 healthy controls (mean age: 14.7 ± 2.2, male/female: 29/22). 3.0 T; axial T2 mapping acquired using a 2D turbo spin-echo sequence. MRI examination was conducted 2-4 months after first LPD. T2 values were calculated in manually segmented cartilage area via averaging over three middle level slices in six cartilage regions: deep, intermediate, superficial layers, and medial lateral parts. ANOVA analysis with Tukey's multiple comparison test, one-vs.-rest logistic regression analysis. The threshold of significance was set at P < 0.05. In lateral patellar cartilage, a significant increase in T2 values was found in deep and intermediate layers in both patient groups with mild (deep: 34.7 vs. 31.3 msec, intermediate: 38.7 vs. 34.6 msec, effect size = 0.55) and severe (34.8 vs. 31.3 msec, 39.1 vs. 34.6 msec, 0.55) LPD consequences as compared to controls. In the medial facet, only severe cartilage damage showed significant prolongation of T2 times in the deep layer (34.3 vs. 30.7 msec, 0.55). No significant changes in T2 values were found in the lateral superficial layer (P = 0.99), whereas mild chondromalacia resulted in a significant decrease of T2 in the medial superficial layer (41.0 vs. 43.8 msec, 0.55). The study revealed substantial difference in T2 changes after LPD between medial and lateral areas of patellar cartilage. 2 TECHNICAL EFFICACY STAGE: 2.

In vitro digestibility of rare sugar (D‐allulose) added pectin–soy protein gels

SummaryConfectionery gels are known to be high‐caloric products due their high sugar content. Changing their formulations by substituting the sugar with alternative natural sweeteners and functionalising them, the addition of proteins has gained attention. Understanding the rate of digestion of these products is also important for selecting the appropriate formulation. In this study, in vitro gastric digestion behaviour of the gels formulated with D‐allulose, a low‐calorie rare sugar, soy protein isolate (SPI) (1%, 2.5%) and pectin (4%) were examined. Digestion decreased the hardness of the gels (P &lt; 0.05), but, at 2.5% SPI concentration. Moisture content of the samples increased after digestion and presence of SPI induced higher water uptake. At the end of 2 h of digestion, 1% soy protein isolate containing gels had the highest brix values showing that after a certain concentration, soy protein isolate governed the system due to improved soy protein–pectin interaction or due to improved gelation with Maillard reaction. NMR relaxometry experiments further confirmed the changes in the gels with the increase in T2 values. Power law model was fitted for the dissolution behaviour using the oBrix values of the digestion medium. Dissolution of sugar and the contribution of SPI to the gel network were clearly observed in SEM images. Results showed that these gels had the potential to slow down the emptying rate of stomach thus could lead to ‘fullness’ for a longer time.

P11.13 Radiotherapy combined with a multimodal imaging approach in a glioblastoma preclinical model

Abstract BACKGROUND Glioblastoma multiforme (GBM) carries a poor prognosis, partly due to biological and anatomical heterogeneity. Although radiotherapy (RT) is effective, high doses damage surrounding healthy tissues. Multimodal imaging with Magnetic Resonance (MRI) and Positron Emission Tomography (PET) may represent a useful approach for identifying GBM heterogeneity and visualising metabolic tumour properties. PET radiotracer [18F]-fluciclovine is preferentially accumulated in gliomas compared to healthy brain tissue via the cellular transport systems, LAT1 and ASCT2. In this study the effect of fractionated RT using multimodal imaging including [18F]-fluciclovine uptake and immunohistochemistry (IHC) in a GBM preclinical model will be validated. MATERIAL AND METHODS Two C57BL/6J mice cohorts were injected intracranially (i.c.) with murine CT2A-luc cells and subsequently submitted to multiparametric MRI and [18F]-fluciclovine PET imaging during hemi-brain RT (3Gy on 2 days/each week) for maximum 25 days after i.c. injection. Brains were collected for IHC characterization including LAT1 and ASCT2 staining. RESULTS Preliminary data showed that both MRI and PET were effective modalities to track tumour growth in this model. PET data revealed up to greater than 3-fold increase in SUVmax from regions of interest around the tumour site compared to healthy brain tissue. Time activity curves showed a steady increase in tumour uptake over 90 minutes. MRI showed a 25% increase in T2 values in tumours relative to unaffected contralateral regions. Confirmation of treatment response through matched imaging and IHC are ongoing, from which changes in glioma cell biology as well as amino acid transporter protein levels will be analysed. CONCLUSION These preliminary results show that multimodal imaging presents novel data in the assessment of treatment response in this model and will permit parallel IHC analyses to better define GBM tumour heterogeneity aligned with imaging changes. These data will also inform an on-going clinical study using the same imaging modalities. Work at authors’ labs are supported by an Investigator initiated project from Blue Earth Diagnostics (AS, SCS) and a University of Leeds Biswas studentship (SCS, DS). Daniela Salvatore is also supported by a Scholarship provided by Molecular and Translational Medicine Doctorate School of University of Milan (Italy).

Evaluation of Knee Cartilage Diurnal, Activity, and BMI-Related Variations Using Quantitative T2 Mapping MRI and Fitbit Activity Tracking.

The aim of this study is to evaluate diurnal variation in knee cartilage 3 Tesla magnetic resonance imaging (MRI) T2 mapping relaxation times, as well as activity- and body mass index (BMI)-dependent variability, using quantitative analysis of T2 values from segmented regions of the weight-bearing articular surfaces of the medial and lateral femoral condyles and tibial plateaus. Ten healthy volunteers' daily activity (steps) were tracked with Fitbit pedometers. Sagittal MRI T2 maps were obtained in the morning and afternoon on days 2 and 3. Mean T2 values were analyzed for variation related to the number of steps taken (activity), time of day (diurnal variation), and BMI using mixed effect model. Significant (albeit small) differences in the medial femoral and medial tibial cartilage regions were identified between morning and afternoon scans (diurnal variation). Daily activity did not result in significant changes and increasing BMI only demonstrated a slight increase in T2 values for the lateral tibial plateau. These findings suggest that it may be necessary to control diurnal variation when using quantitative MRI T2 mapping to assess articular cartilage longitudinally in healthy participants. Further investigation is needed to confirm these findings and determine if they also apply to symptomatic patients.

Abstract WMP79: Favorable Outcome of Stroke in Immunodeficient Mice is Preceded by Faster Normalization of T2 Relaxation

Introduction: Despite the success of rtPA and thrombectomy stroke continues to be a major disease burden to our society. Preventing secondary brain injury after stroke, given the broad therapeutic window, has gained increasing interest. It has been hypothesized that immunological processes substantially contribute to secondary brain damage. Indeed, the outcome of stroke in immunodeficient animals is more favorable compared to that in their immunocompetent counterparts. Here, we followed the evolution of stroke in the presence vs. absence of lymphocytes using serial MRI and T2 measurements. Methods: Adult immunodeficient rag2 -/- mice (n=6) and immunocompetent BALB/c mice (n=6) were subjected to stroke by intracerebral injection of 0.5 μl of 5 mM ouabain. Brain T2 relaxation times were measured using an 11.7T scanner at 1, 5, and 16 days following stroke induction. Post-mortem analysis of tissue sections included H&amp;E and immunohistochemical staining for myelin basic protein, neurofilament, CD8, and CD68. Results: While the increase in T2 values was identical for immunocompetent and immunodeficient animals one day post-stroke (70.88±4.58 vs. 69.88±1.78 ms, respectively, p=0.72), the normalization of the T2 relaxation time (“fogging effect”) proceeded faster in immunodeficient animals over the next few days. Over five days, T2 relaxation times decreased in both groups, but it was significantly shorter in immunodeficient animals compared to immunocompetent animals (41.88±3.68 vs. 59.91±14.95 ms, respectively; p&lt;0.001). On day 16, the T2 relaxation time decreased further in both groups and the difference between infarcted area in immunodeficient and immunocompetent animals as well as healthy tissue was no longer observed. Post-mortem analysis revealed a better preservation of infarcted tissue in immunodeficient animals. Conclusions: In immunodeficient rag2 -/- mice, the restoration of T2 relaxation times in the brain is faster and translates into less profound destruction of brain tissue within stroke lesions. We hypothesize that T2 relaxation time can be used for assessment of immunotherapies aimed at the reduction of secondary brain injury in stroke victims.

Automated T2 relaxometry of the hippocampus for temporal lobe epilepsy.

SummaryObjectiveHippocampal sclerosis (HS), the most common cause of refractory temporal lobe epilepsy, is associated with hippocampal volume loss and increased T2 signal. These can be identified on quantitative imaging with hippocampal volumetry and T2 relaxometry. Although hippocampal segmentation for volumetry has been automated, T2 relaxometry currently involves subjective and time‐consuming manual delineation of regions of interest. In this work, we develop and validate an automated technique for hippocampal T2 relaxometry.MethodsFifty patients with unilateral or bilateral HS and 50 healthy controls underwent T1‐weighted and dual‐echo fast recovery fast spin echo scans. Hippocampi were automatically segmented using a multi‐atlas–based segmentation algorithm (STEPS) and a template database. Voxelwise T2 maps were determined using a monoexponential fit. The hippocampal segmentations were registered to the T2 maps and eroded to reduce partial volume effect. Voxels with T2 >170 msec excluded to minimize cerebrospinal fluid (CSF) contamination. Manual determination of T2 values was performed twice in each subject. Twenty controls underwent repeat scans to assess interscan reproducibility.ResultsHippocampal T2 values were reliably determined using the automated method. There was a significant ipsilateral increase in T2 values in HS (p < 0.001), and a smaller but significant contralateral increase. The combination of hippocampal volumes and T2 values separated the groups well. There was a strong correlation between automated and manual methods for hippocampal T2 measurement (0.917 left, 0.896 right, both p < 0.001). Interscan reproducibility was superior for automated compared to manual measurements.SignificanceAutomated hippocampal segmentation can be reliably extended to the determination of hippocampal T2 values, and a combination of hippocampal volumes and T2 values can separate subjects with HS from healthy controls. There is good agreement with manual measurements, and the technique is more reproducible on repeat scans than manual measurement. This protocol can be readily introduced into a clinical workflow for the assessment of patients with focal epilepsy.

Quantitative MR imaging of intra-orbital structures: Tissue-specific measurements and age dependency compared to extra-orbital structures using multispectral quantitative MR imaging

ABSTRACTThe orbit can be affected by unique pathologic conditions and often requires MRI evaluation. The purpose of this study was to investigate the age-related changes in multiple intra-orbital structures using quantitative MRI (qMRI). Thirty-eight subjects (20 males, 18 females; ages 0.5–87 years) underwent MRI with a mixed turbo spin echo sequence. T1 and T2 measurements were obtained within ROI in 6 intra-orbital structures (medial and lateral rectus muscles, medial and lateral retrobulbar fat, lacrimal gland, and optic nerve), and compared with those of corresponding extra-orbital structures (masseter muscle, subcutaneous cheek fat, buccal fat, parotid gland, and frontal white matter). Statistical analyses were performed using Pearson’s correlation coefficients. T1 and T2 values of the extra-ocular muscles increased with age, with higher T1 and T2 values compared to the masseter muscles. Retrobulbar fat showed significant age-associated increases in T1 values in the lateral side and in T2 values in both sides. T1 and T2 values in the lacrimal gland increased with age, while the parotid gland showed an age-associated increase in T2 values and decrease in T1 values. Optic nerves demonstrated age-related changes, similar to that of frontal white matter; rapid decreases with age in T1 and T2 times in early stages of life, and slight increases in T1 and T2 times later in life. Intra-orbital structures demonstrated specific qMRI measurements and aging patterns, which were different from extra-orbital structures. Location-specific age-related changes of intra-orbital structures should be considered in the qMRI assessment of the orbital pathology.

T2-based temperature monitoring in bone marrow for MR-guided focused ultrasound.

BackgroundCurrent clinical protocols for MR-guided focused ultrasound (MRgFUS) treatment of osseous lesions, including painful bone metastases and osteoid osteomas, rely on measurement of the temperature change in adjacent muscle to estimate the temperature of the bone. The goal of this study was to determine if T2-based thermometry could be used to monitor the temperature change in bone marrow during focused ultrasound ablation of bone lesions.MethodsWe investigated the dependence of T2 on temperature in ex vivo bovine yellow bone marrow at 3T and studied the influence of acquisition parameters on the T2 measurements. We examined if T2 changes in red bone marrow caused by the ablation of ex vivo trabecular bone were reversible and measured the patterns of heating and tissue damage. The technique was validated during the ablation of intact ex vivo bone samples and an in vivo animal model.ResultsResults of the calibration experiment showed a linear relationship (7 ms/°C) between T2 change and temperature and could be used to quantify the temperature during heating of up to 60 °C. During trabecular bone ablation, we observed a linear relationship (5.7 ms per °C) between T2 and temperature during the heating stage of the experiment. After cool down, there was residual T2 elevation (~35 ms) in the ablated area suggesting irreversible tissue changes.In ex vivo and in vivo cortical bone ablation experiments, we observed an increase in T2 values in the marrow adjacent to the intersection of the cortical bone and the beam path. The in vivo experiment showed excellent correspondence between the area of T2 elevation in marrow during the ablation and the resulting non-enhancing area in the post-contrast images.ConclusionsIn this study, we have demonstrated that T2-based thermometry can be used in vivo to measure the heating in the marrow during bone ablation. The ability to monitor the temperature within the bone marrow allowed more complete visualization of the heat distribution into the bone, which is important for local lesion control.

Efeito da contração muscular na cartilagem: avaliação morfológica e funcional por imagens de ressonância magnética do joelho após trauma medular

ObjectiveTo evaluate the effect of complete absence of muscle contractions on normal human cartilage in the presence of joint motion. MethodsPatients with complete acute spinal cord injuries were enrolled. All patients underwent magnetic resonance imaging (MRI) on both knees as soon as their medical condition was stable and at six months after the primary lesion. All patients received rehabilitation treatment that included lower‐limb passive motion exercises twice a day. The MRIs were analyzed by two radiologists with expertise in musculoskeletal disorders. A region of interest was established at the patellar facets and trochlea, and T2 relaxation times were calculated. The area under the cartilage T2 relaxation time curve was calculated and standardized. ResultsFourteen patients with complete spinal cord injuries were enrolled, but only eight patients agreed to participate in the study and signed the informed consent statement. Two patients could not undergo knee MRI due to their clinical conditions. Initial knee MRIs were performed on six patients. After six months, only two patients underwent the second bilateral knee MRI. Both patients were neurologically classified as Frankel A. An increase in T2 values on the six‐month MRI was observed for both knees, especially in the patellofemoral joint. ConclusionThe absence of muscle contractions seems to be deleterious to normal human knee cartilage even in the presence of a normal range of motion. Further studies with a larger number of patients, despite their high logistical complexity, must be performed to confirm this hypothesis.

Prospective In Vivo Comparison of Damaged and Healthy-Appearing Articular Cartilage Specimens in Patients With Femoroacetabular Impingement: Comparison of T2 Mapping, Histologic Endpoints, and Arthroscopic Grading

To describe T2 mapping values in arthroscopically determined International Cartilage Repair Society (ICRS) grades in damaged and healthy-appearing articular cartilage waste specimens from arthroscopic femoroacetabular impingement (FAI) treatment. Furthermore, we sought to compare ICRS grades of the specimens with biochemical, immunohistochemistry and histologic endpoints and assess correlations with T2 mapping. Twenty-four patients were prospectively enrolled, consecutively, between December 2011 and August 2012. Patients were included if they were aged 18years or older and met criteria that followed the clinical indications for arthroscopy to treat FAI. Patients with prior hip trauma including fracture or dislocation or who have undergone prior hip surgery were excluded. All patients received a preoperative sagittal T2 mapping scan of the hip joint. Cartilage was graded intraoperatively using the ICRS grading system, and graded specimens were collected as cartilage waste for histologic, biochemical, and immunohistochemistry analysis. Forty-four cartilage specimens (22 healthy-appearing, 22 damaged) were analyzed. Median T2 values were significantly higher among damaged specimens (55.7 ± 14.9ms) than healthy-appearing specimens (49.3 ± 12.3ms; P= .043), which was most exaggerated among mild (grade 1 or 2) defects where the damaged specimens (58.1 ± 16.4ms) were significantly higher than their paired healthy-appearing specimens (48.7 ± 15.4ms; P=.026). Severely damaged specimens (grade 3 or 4) had significantly lower cumulative H&E than their paired healthy-appearing counterparts (P= .02) but was not statistically significant among damaged specimens with mild (grade 1 or 2) defects (P= .198). Among healthy-appearing specimens, median T2 and the percentage of collagen fibers oriented parallel were significantly correlated (rho= 0.425, P= .048). This study outlines the potential for T2 mapping to identify early cartilage degeneration in patients undergoing arthroscopy to treat FAI. Findings in ICRS grade 1 and 2 degeneration corresponded to an increase in T2 values. Further biochemical evaluation revealed a significant difference between healthy-appearing cartilage and late degeneration in cumulative H&E as well as significantly lower percentage of collagen fibers oriented parallel and a higher percentage of collagen fibers oriented randomly when considering all grades of cartilage damage. Level II, prospective comparative study.

T2 mapping of articular cartilage of the glenohumeral joint at 3.0T in healthy volunteers: a feasibility study.

The purpose of this study was to assess the T2 values of the glenohumeral joint cartilage in healthy asymptomatic individuals at 3.0T and to analyze the T2 profile of the humeral cartilage. This prospective study was approved by our institutional review board and written informed consent was obtained. Thirteen subjects (mean age, 28.6years; age range, 24-33 years) were included and underwent multiecho spin-echo T2-weighted MR imaging and T2 mapping was acquired. Regions of interest were placed on the humeral cartilage and glenoid cartilage on oblique coronal images. T2 profiles of humeral cartilage were measured from the bone-cartilage interface to the articular surface. Intra-observer agreement was analyzed using intraclass correlation coefficient (ICC). All 13 joints showed normal appearance on conventional T2-weighted images. The mean T2 values of humeral and glenoid cartilage were 50.5 ± 12.1 and 49.0 ± 9.9ms, respectively. Intra-observer agreement was good, as determined by ICC (0.736). Longer T2 values were observed at the articular surface with a tendency to decrease toward the bone-cartilage interface. The mean cartilage T2 value was 69.03 ± 21.2ms at the articular surface and 46.99 ± 19.6ms at the bone-cartilage interface. T2 values of the glenohumeral joint cartilage were similar to reported values of cartilage in the knee. The T2 profile of normal humeral cartilage showed a spatial variation with an increase in T2 values from the subchondral bone to the articular surface.

Effect of muscle contractions on cartilage: morphological and functional magnetic resonance imaging evaluation of the knee after spinal cord injury

ObjectiveTo evaluate the effect of complete absence of muscle contractions on normal human cartilage in the presence of joint motion. MethodsPatients with complete acute spinal cord injuries were enrolled. All patients underwent magnetic resonance imaging (MRI) on both knees as soon as their medical condition was stable and at six months after the primary lesion. All patients received rehabilitation treatment that included lower-limb passive motion exercises twice a day. The MRIs were analyzed by two radiologists with expertise in musculoskeletal disorders. A region of interest was established at the patellar facets and trochlea, and T2 relaxation times were calculated. The area under the cartilage T2 relaxation time curve was calculated and standardized. ResultsFourteen patients with complete spinal cord injuries were enrolled, but only eight patients agreed to participate in the study and signed the informed consent statement. Two patients could not undergo knee MRI due to their clinical conditions. Initial knee MRIs were performed on six patients. After six months, only two patients underwent the second bilateral knee MRI. Both patients were neurologically classified as Frankel A. An increase in T2 values on the six-month MRI was observed for both knees, especially in the patellofemoral joint. ConclusionThe absence of muscle contractions seems to be deleterious to normal human knee cartilage even in the presence of a normal range of motion. Further studies with a larger number of patients, despite their high logistical complexity, must be performed to confirm this hypothesis.

Assessment of diabetic peripheral neuropathy in streptozotocin-induced diabetic rats with magnetic resonance imaging

To determine the role of magnetic resonance (MR) imaging and quantitative T2 value measurements in the assessment of diabetic peripheral neuropathy (DPN). Sequential MR imaging, T2 measurement, and quantitative sensory testing of sciatic nerves were performed in streptozotocin-induced diabetic rats (n = 6) and normal control rats (n = 6) over a 7-week follow-up period. Histological assessment was obtained from 48 diabetic rats and 48 control rats once weekly for 7weeks (n = 6 for each group at each time point). Nerve signal abnormalities were observed, and the T2 values, mechanical withdrawal threshold (MWT), and histological changes were measured and compared between diabetic and control animals. Sciatic nerves in the diabetic rats showed a gradual increase in T2 values beginning at 2weeks after the induction (P = 0.014), while a decrease in MWT started at 3weeks after the induction (P = 0.001). Nerve T2 values had a similar time course to sensory functional deficit in diabetic rats. Histologically, sciatic nerves of diabetic rats demonstrated obvious endoneural oedema from 2 to 3weeks after the induction, followed by progressive axonal degeneration, Schwann cell proliferation, and coexistent disarranged nerve regeneration. Nerve T2 measurement is potentially useful in detecting and monitoring diabetic neuropathy. • Sciatic nerves in diabetic rats showed a gradual increase in T2 values • Nerve T2 values were negatively correlated with sensory function impairment • Longitudinal T2 values can be used to monitor the disease progress • Nerve degeneration contributed mainly to progressive prolongation of nerve T2 values.

T2 mapping in patellar chondromalacia

ObjectiveTo study the correlation between the T2 relaxation times of the patellar cartilage and morphological MRI findings of chondromalacia. MethodsThis prospective study comprises 50 patients, 27 men and 23 women suffering of anterior knee pain (mean age: 29.7, SD 8.3 years; range: 16–45 years).MRI of 97 knees were performed in these patients at 1.5T magnet including sagittal T1, coronal intermediate, axial intermediate fat sat and T2 mapping. Chondromalacia was assessed using a modified version of Noyes classification. The relaxation time, T2, was studied segmenting the full thickness of the patellar cartilage in 12 areas: 4 proximal (external facet–proximal–lateral (EPL), external facet–proximal–central (EPC), internal facet–proximal–central (IPC), internal facet–proximal–medial (IPM), 4 in the middle section (external facet–middle–lateral (EML), external facet–middle–central (EMC), internal facet–middle–central (IMC), internal facet–middle–medial (IMM) and 4 distal (external facet–distal–lateral (EDL), external facet–distal–central (EDC), internal facet–distal–central (IDC), internal facet–distal–medial (IDM). ResultsT2 values showed a significant increase in mild chondromalacia regarding normal cartilage in most of the cartilage areas (p<0.05), except in the internal distal facet (IDC and IDM), EPC, EDL, and IMM. Severe chondromalacia was characterized by a fall of T2 relaxation times with loss of statistical significant differences in comparison with normal cartilage, except in EMC and IMC, where similar values as mild chondromalacia were maintained (p<0.05). ConclusionsSteepest increase in T2 values of patellar cartilage occurs in early stages of patellar cartilage degeneration. Progression of morphologic changes of chondromalacia to more severe degrees is associated to a new drop of T2 relaxation times approaching basal values in most of the areas of the patellar cartilage, except in the central area of the middle section, where T2 values remain increased.

Magnetic resonance mapping of the rim of articular cartilage defects of the patella

Elevated T2-values of articular cartilage are associated with an increase in cartilage water that results from a damaged collagen matrix, and provide a marker for cartilage damage. We used T2 mapping to analyse the rim of cartilage defects that appeared to be intact on the morphological sequences, to determine whether there are early biochemical changes already present. We calculated T2 values for the rim of cartilage defects in 25 patients and compared these values to another area of control cartilage in these patients. A highly significant increase in T2 values of the deep, superficial, and global layer of the rim versus the control cartilage was measured. ANOVA showed a significant correlation of the defect levels with the T2 values of the deep and global zone of the adjacent cartilage tissue, but not with the superficial zone. Although cartilage appears to be intact on morphological sequences, T2 mapping can show a loss of structural anisotropy of collagen and the associated increase in cartilage water that indicates the destruction of the adjacent cartilage. Preoperative information about the degree of damage of the collagen matrix will support decision making for cartilage repair.

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

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. 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. 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). 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. III.

Effect of short-term unloading on T2 relaxation time in the lumbar intervertebral disc—in vivo magnetic resonance imaging study at 3.0 tesla

Background contextDiurnal changes in T2 values, indicative for changes in water content, have been reported in the lumbar intervertebral discs. However, data concerning short-term T2 changes are missing.PurposeThe purpose of this study was to investigate the short-term effects of unloading on T2 values in lumbar intervertebral discs in vivo.Study designExperimental study with repeated measurements of lumbar discs T2 relaxation time during a period of 38 minutes of supine posture.Patient sampleForty-one patients with acute or chronic low back pain (visual analog scale ≥3).Outcome measuresT2 relaxation time in the intervertebral disc, lumbar lordosis angle, and intervertebral disc height.MethodsForty-one patients (mean age, 41.6 years) were investigated in the supine position using a 3-tesla magnetic resonance system. Sagittal T2 mapping was performed immediately after unloading and after a mean delay of 38 minutes. No patient movement was allowed between the measurements. One region of interest (ROI) was manually placed in both the anterior and the posterior annulus fibrosus (AF) and three ROIs in the nucleus pulposus (NP).ResultsThere was a statistically significant decrease in the anterior NP (−2.7 ms; p<.05) and an increase in T2 values in the posterior AF (+3.5 ms; p<.001). Discs with initially low T2 values in the NP showed minor increase in the posterior AF (+1.6 ms; p<.05), whereas a major increase in the posterior AF was found in discs with initially high T2 values in the NP (+6.8 ms; p=.001). Patients examined in the morning showed no differences, but those investigated in the afternoon showed a decrease in the anterior NP (−5.3 ms; p<.05) and an increase in the posterior AF (+7.8 ms; p=.002). No significant differences were observed in other regions. Correlation analysis showed moderate correlations between the time of investigation and T2 changes in the posterior AF (r=0.46; p=.002).ConclusionsA shift of water from the anterior to the posterior disc regions seems to occur after unloading the lumbar spine in the supine position. The clinical relevance of these changes needs to be investigated.

Early in vivo MR spectroscopy findings in organophosphate‐induced brain damage—potential biomarkers for short‐term survival

Organophosphates are highly toxic substances, which cause severe brain damage. The hallmark of the brain injury is major convulsions. The goal of this study was to assess the spatial and temporal MR changes in the brain of paraoxon intoxicated rats. T2-weighted MRI and ¹H-MR-spectroscopy were conducted before intoxication, 3 h, 24 h, and 8 days postintoxication. T2 prolongation mainly in the thalami and cortex was evident as early as 3 h after intoxication (4-6% increase in T2 values, P < 0.05). On spectroscopy, N-acetyl aspartate (NAA)/creatine and NAA/choline levels significantly decreased 3 h postintoxication (>20% decrease, P < 0.005), and 3 h lactate peak was evident in all intoxicated animals. On the 8th day, although very little T2 changes were evident, NAA/creatine and choline/creatine were significantly decreased (>15%, P < 0.05). Animals who succumbed had extensive cortical edema, significant higher lactate levels and a significant decrease in NAA/creatine and NAA/choline levels compared to animals which survived the experiment. Organophosphates-induced brain damage is obvious on MR data already 3 h postintoxication. In vivo spectroscopic changes are more sensitive for assessing long-term injury than T2-weighted MR imaging. Early spectroscopic findings might be used as biomarkers for the severity of the intoxication and might predict early survival.