Changes In T2 Research Articles

Stress native T1 and native T2 mapping compared to myocardial perfusion reserve in long-term follow-up of severe Covid-19

Severe Covid-19 may cause a cascade of cardiovascular complications beyond viral pneumonia. The severe inflammation may affect the microcirculation which can be assessed by cardiovascular magnetic resonance (CMR) imaging using quantitative perfusion mapping and calculation of myocardial perfusion reserve (MPR). Furthermore, native T1 and T2 mapping have previously been shown to identify changes in myocardial perfusion by the change in native T1 and T2 during adenosine stress. However, the relationship between native T1, native T2, ΔT1 and ΔT2 with myocardial perfusion and MPR during long-term follow-up in severe Covid-19 is currently unknown. Therefore, patients with severe Covid-19 (n = 37, median age 57 years, 24% females) underwent 1.5 T CMR median 292 days following discharge. Quantitative myocardial perfusion (ml/min/g), and native T1 and T2 maps were acquired during adenosine stress, and rest, respectively. Both native T1 (R2 = 0.35, p < 0.001) and native T2 (R2 = 0.28, p < 0.001) correlated with myocardial perfusion. However, there was no correlation with ΔT1 or ΔT2 with MPR, respectively (p > 0.05 for both). Native T1 and native T2 correlate with myocardial perfusion during adenosine stress, reflecting the coronary circulation in patients during long-term follow-up of severe Covid-19. Neither ΔT1 nor ΔT2 can be used to assess MPR in patients with severe Covid-19.

Evaluation of fetoplacental oxygenation in a rat model of gestational diabetes mellitus using BOLD-MRI at 7.0-T

Objective: To compare the differences in blood oxygen level-dependent (BOLD) parameters following maternal hyperoxia between normal pregnancy and pregnancy in the rat model of gestational diabetes mellitus (GDM). Methods: GDM was induced by high-fat and sucrose diet (HFS) combined with an intraperitoneal injection of streptozotocin (STZ). On embryonic day 19 (E19), the two groups of pregnant rats were imaged using a 7.0-T animal MRI scanner. TurboRARE was initially used to localize the fetoplacental units (FPUs). Next, multiple gradient echo BOLD was performed during the air and oxygen inhalation periods. T2* map was then generated, and the baseline T2* and absolute changes in T2* value (ΔT2*, difference between T2*oxy and T2*air) were calculated. Following the MRI scan, the placentas and fetuses were aseptically stripped, weighed, and immunostained. Results: Nine rats were used in this study. After maternal oxygen inhalation, T2* increased significantly in all subjects in both groups. The ΔT2* for the placenta (5.97 vs. 7.81 msec; P = 0.007) and fetal brain (2.23 vs. 3.97 msec; P = 0.005) differed significantly between the GDM and control groups. Histochemical detection of placental glycogen content and inflammatory cytokines (IL-6 and TNF-α) showed significantly higher levels in the GDM than in the normal placenta. Conclusions: BOLD-MRI revealed abnormalities in the fetoplacental response to maternal hyperoxygenation in rats with GDM. We believe that this approach can potentially be used to evaluate placental dysfunction and assess the state of the fetus during pregnancy with GDM.

Post-COVID-19 vaccination myocarditis: a prospective cohort study pre and post vaccination using cardiovascular magnetic resonance

BackgroundConcerns about COVID-19 vaccination induced myocarditis or subclinical myocarditis persists in some populations. Cardiac magnetic resonance imaging (CMR) has been used to detect signs of COVID-19 vaccination induced myocarditis. This study aims to: (i) characterise myocardial tissue, function, size before and after COVID-19 vaccination, (ii) determine if there is imaging evidence of subclinical myocardial inflammation or injury after vaccination using CMR. MethodsSubjects aged ≥ 12yrs old without prior COVID-19 or COVID-19 vaccination underwent two CMR examinations: first, ≤ 14 days before the first COVID-19 vaccination and a second time ≤ 14 days after the second COVID-19 vaccination. Biventricular indices, ejection fraction (EF), global longitudinal strain (GLS), late gadolinium enhancement (LGE), left ventricular (LV) myocardial native T1, T2, extracellular volume (ECV) quantification, lactate dehydrogenase (LDH), white cell count (WCC), C-reactive protein (CRP), NT-proBNP, troponin-T, electrocardiogram (ECG), and 6-min walk test were assessed in a blinded fashion. Results67 subjects were included. First and second CMR examinations were performed a median of 4 days before the first vaccination (interquartile range 1–8 days) and 5 days (interquartile range 3–6 days) after the second vaccination respectively. No significant change in global native T1, T2, ECV, LV EF, right ventricular EF, LV GLS, LGE, ECG, LDH, troponin-T and 6-min walk test was demonstrated after COVID-19 vaccination. There was a significant WCC decrease (6.51 ± 1.49 vs 5.98 ± 1.65, p = 0.003) and CRP increase (0.40 ± 0.22 vs 0.50 ± 0.29, p = 0.004). ConclusionThis study found no imaging, biochemical or ECG evidence of myocardial injury or inflammation post COVID-19 vaccination, thus providing some reassurance that COVID-19 vaccinations do not typically cause subclinical myocarditis.

Reproducibility of the new Leishmania vaccine: Changes in T1, T2 and spleen white pulp responses after re- exposure to live promastigote of Leishmania major

Introduction: Human leishmaniasis is distributed worldwide and is mainly in the tropics and subtropics, with a prevalence of 12 million cases and an approximately incidence of 0.5 million cases of VL and 1.5 million cases of cutaneous leishmaniasis (CL). Leishmania parasites are vector-born protozoan pathogens found in tropical and subtropical regions of both the old and new world. The disease in human can be divided into cutaneous, visceral, and mucosal syndromes. The aim of this study was more experiments over our previous new formulation leishmania major vaccine which had satisfactory experiments results. Method: For detail procedure refers to author’s previous publications. Briefly, hundred and twenty Balb/cmice were randomly divided into four groups as LT, LB, LBT and control groups. LT, LB and LBT injected subcutaneously with the antigen and the same booster doses with two weeks intervals. The expansion rates of the spleen white pulp size was evaluated using a light microscope and the levels of the serum Th1 (IFN- γ, IL-12) and Th2 (IL-4, IL-10) cytokines measured with the ELISA method. Results: Comparing to the LT and LB groups, the LBT group had highest levels of serum IL12, lowest levels of IL10 and highest increase in the spleen white pulp size. Significant correlation was observed between IL12 and IL10 but not IFN gamma or IL4. Conclusion: present study indicated that the LBT group which received crude cocktail leishmania antigen plus alcoholic extract of Teucrium polium and BCG as adjuvant showed satisfactory cytokines profile comparing to groups LT and LB,since highest levels of IL12 and lower levels of IL10 which could help the infected subjects to inhibit or eradication the intracellular leishmania amastigotes, and also was seen highest increase in the spleen white-pulp size which pointed to the synergistic effects of alcoholic extract of T. polium and BCG.

Reproducibility of the new Leishmania vaccine: Changes in T1, T2 and spleen white pulp responses after re- exposure to live promastigote of Leishmania major

Reproducibility of the new Leishmania vaccine: Changes in T1, T2 and spleen white pulp responses after re- exposure to live promastigote of Leishmania major

The effect of interactions between BMI and sustained depressive symptoms on knee osteoarthritis over 4 years: data from the osteoarthritis initiative

BackgroundTo assess the compound effects of BMI and sustained depressive symptoms on changes in knee structure, cartilage composition, and knee pain over 4 years using statistical interaction analyses.MethodsOne thousand eight hundred forty-four individuals from the Osteoarthritis Initiative Database were analyzed at baseline and 4-year follow-up. Individuals were categorized according to their BMI and presence of depressive symptoms (based on the Center for Epidemiological Studies Depression Scale (threshold≥16)) at baseline and 4-year follow-up. 3 T MRI was used to quantify knee cartilage T2 over 4 years, while radiographs were used to assess joint space narrowing (JSN). Mixed effects models examined the effect of BMI-depressive symptoms interactions on outcomes of cartilage T2, JSN, and knee pain over 4-years.ResultsThe BMI-depressive symptoms interaction was significantly associated with knee pain (p < 0.001) changes over 4 years, but not with changes in cartilage T2 (p = 0.27). In women, the BMI-depressive symptoms interaction was significantly associated with JSN (p = 0.01). In a group-based analysis, participants with obesity and depression had significantly greater 4-year changes in knee pain (coeff.(obesity + depression vs. no_obesity + no_depression) = 4.09, 95%CI = 3.60–4.58, p < 0.001), JSN (coeff. = 0.60, 95%CI = 0.44–0.77, p < 0.001), and cartilage T2 (coeff. = 1.09, 95%CI = 0.68–1.49, p < 0.001) than participants without depression and normal BMI.ConclusionsThe compound effects of obesity and depression have greater impact on knee pain and JSN progression compared to what would be expected based on their individual effects.

Time Course Changes of Synthetic Relaxation Time During Neoadjuvant Chemotherapy in Breast Cancer: The Optimal Parameter for Treatment Response Evaluation.

Synthetic MRI (syMRI) has enabled quantification of multiple relaxation parameters (T1/T2 relaxation time [T1/T2], proton density [PD]), and their longitudinal change during neoadjuvant chemotherapy (NAC) promises to be valuable parameters for treatment response evaluation in breast cancer. To investigate the time course changes of syMRI parameters during NAC and evaluate their value as predictors for pathological complete response (pCR) in breast cancer. Retrospective, longitudinal. A total of 129 women (median age, 50 years; range, 28-69 years) with locally advanced breast cancer who underwent NAC; all performed multiple conventional breast MRI examinations with added syMRI during NAC. A 3.0 T, T1-weighted dynamic contrast enhanced and syMRI acquired by a multiple-dynamic, multiple-echo sequence. Breast MRI was set at four time-points: baseline, after one cycle, after three or four cycles of NAC and preoperation. SyMRI parameters and tumor diameters were measured and their changes from baseline were calculated. All parameters were compared between pCR and non-pCR. Interaction between syMRI parameters and clinicopathological features was analyzed. Mann-Whitney U tests, random effects model of repeated measurement, receiver operating characteristic (ROC) analysis, interaction analysis. Median synthetic T1/T2/PD and tumor diameter generally decreased throughout NAC. Absolute T1 at early-NAC, T1, and PD at mid-NAC were significantly lower in the pCR group. After early-NAC, the T1 change was significantly higher in the pCR (median ± IQR, 18.17 ± 11.33) than the non-pCR group (median ± IQR, 10.90 ± 10.03), with the highest area under the ROC curves (AUC) of 0.769 (95% CI, 0.684-0.838). Interaction analysis showed that histological grade III patients had higher odds ratio (OR) (OR=1.206) compared to grade II patients (OR=1.067). Synthetic T1 changes after one cycle of NAC maybe useful for early evaluating NAC response in breast cancer during whole treatment cycles. However, its discriminative ability is significantly affected by histological grade. 4 TECHNICAL EFFICACY: Stage 2.

Integrating MR imaging with full-surface indentation mapping of femoral cartilage in an ex vivo porcine stifle

The potential of MRI to predict cartilage mechanical properties across an entire cartilage surface in an ex vivo model would enable novel perspectives in modeling cartilage tolerance and predicting disease progression. The purpose of this study was to integrate MR imaging with full-surface indentation mapping to determine the relationship between femoral cartilage thickness and T2 relaxation change following loading, and cartilage mechanical properties in an ex vivo porcine stifle model. Matched-pairs of stifle joints from the same pig were randomized into either 1) an imaging protocol where stifles were imaged at baseline and after 35 min of static axial loading; and 2) full surface mapping of the instantaneous modulus (IM) and an electromechanical property named quantitative parameter (QP). The femur and femoral cartilage were segmented from baseline and post-intervention scans, then meshes were generated. Coordinate locations of the indentation mapping points were rigidly registered to the femur. Multiple linear regressions were performed at each voxel testing the relationship between cartilage outcomes (thickness change, T2 change) and mechanical properties (IM, QP) after accounting for covariates. Statistical Parametric Mapping was used to determine significance of clusters. No significant clusters were identified; however, this integrative method shows promise for future work in ex vivo modeling by identifying spatial relationships among variables.

AGREEMENT OF AUTOMATED LAMINAR FEMOROTIBIAL CARTILAGE TRANSVERSE RELAXATION TIME (T2) ANALYSIS WITH MANUAL EXPERT SEGMENTATION

Articular cartilage transverse relaxation time (T2) on MRI has been observed to reflect collagen integrity, orientation, and hydration, and to be associated with cartilage histological grading, mechanical properties, and early knee OA status. Previously, we reported high agreement of cartilage segmentations obtained from multi echo spin echo (MESE) MRI, using fully automated deep learning methods, in comparison with manual ones. As these results were based on 3T MRI (of the OAI), we here explored the agreement between fully automated segmentation of MESE cartilage at 1.5T. To analyze the agreement between automated, U-Net-based segmentation of femorotibial cartilage from MESE by convolutional neural networks vs. manual expert segmentation with quality control of the same images, and to compare laminar femorotibial cartilage T2 between both approaches. We studied 20 ACL-deficient patients with persistent dynamic knee instability (non-copers), 22 without instability (copers), 13 with surgical ACL reconstruction, and 16 healthy controls. Further patient characterizations are described in a parallel abstract at this conference. Sagittal MESE MRIs were acquired at 1.5T (Siemens Avanto; slice thickness/spacing 3/3.5mm, in-plane resolution 0.31mm, TR 1500ms, TE 9.7/19.4/29.1/38.8/48.5/58.2/67.9ms), at baseline (n=71) and 1 year later (n=55). Manual cartilage segmentation was done by experienced readers, with quality control by an expert (Fig. 1). The U-Net was trained using medial and lateral MRIs from the same scanner (training/ validation set n=50/9) obtained in volleyball athletes of different age groups, and in patients with posterior cruciate ligament (PCL) surgery, segmented by the above readers. Training of the U-net was performed for both all 7 echos and only the 1st echo. Automated U-Net segmentation was then applied to the current study MRIs, without manual intervention or correction. Yet, automated post-processing was employed to correct obvious segmentation errors. The agreement between manual and automated U-Net-based segmentations was evaluated using the Dice Similarly Coefficient (DSC), and by evaluating systematic differences and correlations in cartilage T2 of the 50% superficial and 50% deep layer. When all echoes were used for training, the overall DSC was 0.89 for MT/LT, and 0.83 for cMF/cLF. When only the 1st echo was used,DSCs were 0.87/0.88 and 0.81/0.79. Automated analysis overestimated the segmented tissue volume significantly in most regions, with correlations ranging from 0.93-0.96 for all echoes, and from 0.87-0.94 for the 1st echo. Deep layer T2 across the joint was 45.7ms for manual analysis, 45.7ms with all echoes, and 46.1ms with the 1st echo model; superficial layer T2 was 52.1, 53.2 and 54.4ms. There were statistically significant (albeit small) differences of automated vs. manual analysis across most regions for the superficial layer, and for LT and cLF in the deep layer. The correlation of deep layer T2 across the plates ranged from 0.91-0.99 for all echoes model, and from 0.85-0.98 for the 1st echo model, and that of the superficial T2 from 0.86-0.97, and from 0.73-0.81. Fully automated (U-Net-based) laminar analysis of femorotibial cartilage T2 appears feasible at 1.5T, albeit the agreement for T2 at 3T, and that for cartilage thickness was previously reported to be higher. The agreement with manual analysis was greater when training a model with 7 echoes than with the 1st echo only, and it was greater for the deep than for the superficial layer. No significant change in T2 was observed over 1 year; thus, longer intervals may be required for longitudinal validation.

Effects of long-term running on the structure and biochemical composition of knee cartilage in males: a cross-sectional study.

Running has been widely recognized as a beneficial activity for improving physical fitness, but it can also increase the risk of running-related injuries (RRIs). This study aims to assess the impact of long-term running on the structural and biochemical composition of the knee. This study recruited a total of 32 participants, including 16 male recreational runners, aged 28-49 years, with a running experience of 2-7 years, and 16 matched sedentary controls. Magnetic resonance (MR) scans of T2* mapping and three-dimensional double-echo steady-state (3D-DESS) were performed on all participants. The volumes, thickness, and T2* values of joint articular cartilage were obtained via automatic segmentation software. Compared with the sedentary controls, runners exhibited significant increases in the volumes of both the femoral medial articular cartilage and the tibial medial articular cartilage. Additionally, there were significant increases in the thickness of several cartilage regions, including femoral medial cartilage, femoral medial articular cartilage, femoral medial thickness, femoral lateral cartilage, and tibial medial articular cartilage. Notably, the T2* values in the femoral lateral and tibial lateral cartilage of runners decreased significantly, while those in the patellar cartilage and medial tibial cartilage increased significantly. Runner pace was negatively correlated with the overall knee cartilage thickness (r=-0.556; P=0.02), femoral cartilage thickness (r=-0.533; P=0.03), and volume (r=-0.532; P=0.03) but positively correlated with the T2* value of the patellar cartilage (r=0.577; P=0.01). Our study suggests that long-term mechanical stress from running may lead to increased thickness and volume in certain knee joint cartilage regions, possibly enhancing the functional adaptability of knee cartilage. The varying changes in T2* value in the tibial and fibular cartilage areas may indicate differing adaptability to pressure.

Dynamic Cardiac Magnetic Resonance Fingerprinting During Vasoactive Breathing Maneuvers: First Results.

Cardiac magnetic resonance fingerprinting (cMRF) enables simultaneous mapping of myocardial T1 and T2 with very short acquisition times. Breathing maneuvers have been utilized as a vasoactive stress test to dynamically characterize myocardial tissue in vivo. We tested the feasibility of sequential, rapid cMRF acquisitions during breathing maneuvers to quantify myocardial T1 and T2 changes. We measured T1 and T2 values using conventional T1 and T2-mapping techniques (modified look locker inversion [MOLLI] and T2-prepared balanced-steady state free precession), and a 15 heartbeat (15-hb) and rapid 5-hb cMRF sequence in a phantom and in 9 healthy volunteers. The cMRF5-hb sequence was also used to dynamically assess T1 and T2 changes over the course of a vasoactive combined breathing maneuver. In healthy volunteers, the mean myocardial T1 of the different mapping methodologies were: MOLLI 1,224 ± 81 ms, cMRF15-hb 1,359 ± 97 ms, and cMRF5-hb 1,357 ± 76 ms. The mean myocardial T2 measured with the conventional mapping technique was 41.7 ± 6.7 ms, while for cMRF15-hb 29.6 ± 5.8 ms and cMRF5-hb 30.5 ± 5.8 ms. T2 was reduced with vasoconstriction (post-hyperventilation compared to a baseline resting state) (30.15 ± 1.53 ms vs. 27.99 ± 2.07 ms, p = 0.02), while T1 did not change with hyperventilation. During the vasodilatory breath-hold, no significant change of myocardial T1 and T2 was observed. cMRF5-hb enables simultaneous mapping of myocardial T1 and T2, and may be used to track dynamic changes of myocardial T1 and T2 during vasoactive combined breathing maneuvers.

Evaluating whole-brain tissue-property changes in MRI-negative pharmacoresistant focal epilepsies using MR fingerprinting.

We aim to quantify whole-brain tissue-property changes in patients with magnetic resonance imaging (MRI)-negative pharmacoresistant focal epilepsy by three-dimensional (3D) magnetic resonance fingerprinting (MRF). We included 30 patients with pharmacoresistant focal epilepsy and negative MRI by official radiology report, as well as 40 age- and gender-matched healthy controls (HCs). MRF scans were obtained with 1 mm3 isotropic resolution. Quantitative T1 and T2 relaxometry maps were reconstructed from MRF and registered to the Montreal Neurological Institute (MNI) space. A two-sample t test was performed in Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FSL) to evaluate significant abnormalities in patients comparing to HCs, with correction by the threshold-free cluster enhancement (TFCE) method. Subgroups analyses were performed for extra-temporal epilepsy/temporal epilepsy (ETLE/TLE), and for those with/without subtle abnormalities detected by morphometric analysis program (MAP), to investigate each subgroup's pattern of MRF changes. Correlation analyses were performed between the mean MRF values in each significant cluster and seizure-related clinical variables. Compared to HCs, patients exhibited significant group-level T1 increase ipsilateral to the epileptic origin, in the mesial temporal gray matter (GM) and white matter (WM), temporal pole GM, orbitofrontal GM, hippocampus, and amygdala, with scattered clusters in the neocortical temporal and insular GM. No significant T2 changes were detected. The ETLE subgroup showed a T1-increase pattern similar to the overall cohort, with additional involvement of the ipsilateral anterior cingulate GM. The subgroup of MAP+ patients also showed a T1-increase pattern similar to the overall cohort, with additional cluster in the ipsilateral lateral orbitofrontal GM. Higher T1 was associated with younger seizure-onset age, longer epilepsy duration, and higher seizure frequency. MRF revealed group-level T1 increase in limbic/paralimbic structures ipsilateral to the epileptic origin, in patients with pharmacoresistant focal epilepsy and no apparent lesions on MRI, suggesting that these regions may be commonly affected by seizures in the epileptic brain. The significant association between T1 increase and higher seizure burden may reflect progressive tissue damage.

TRANSTHORACIC SHOCKS LEAD TO REGIONAL BI-VENTRICULAR DIASTOLIC DYSFUNCTION IN TERRITORIES WITH ACUTE MYOCARDIAL INJURY

<h3>Introduction</h3> Electric defibrillations and cardioversion are standard interventions to terminate arrhythmia. Recent evidence hints to acute post shock myocardial injury. However, that injury may follow unique pathways in every individual. Common functional measures such as ejection fraction are limited in that they represent only global ventricular function. Cardiovascular magnetic resonance feature tracking (CMR-FT) is a technique that can quantify myocardial contraction and relaxation on a regional level. The purpose of this analysis was to investigate the impact of acute myocardial injury after serial transthoracic shocks on regional systolic and diastolic myocardial deformation in a healthy animal model. <h3>Methods</h3> Ten healthy anaesthetized swine were scanned in a 3 Tesla MRI with a standard short axis cine and a clinical T1 mapping sequence in three short axis slices to detect myocardial edema. Five transthoracic shocks with 200 Joules each were applied within five minutes. Five hours post-shock the same images were re-acquired. Six control animals underwent the same protocol without shocks. Changes in regional peak strain as a measure of systolic function, and early diastolic strain rate as a measure of diastolic function were evaluated using CMR-FT analysis in circumferential orientation for both the left (LV) and right ventricle (RV). T1 maps of the LV were analyzed and reported per myocardial AHA segment as a measure of myocardial edema. For the RV, a region of interest (ROI) was contoured in each of the 3 short-axis slices. The regional changes in strain in comparison to the development of myocardial injury (ΔT1 mapping) over the course of 5h were statistically assessed using a mixed effects model accounting for the electrical intervention and multiple measurements per individual. <h3>Results</h3> Global circumferential peak strain worsened in both ventricles (LV: -15.6±3.3% to -13.0±3.6%, p<0.01; RV: -16.1±2.3% to -12.8±4.8%, p=0.03). Additionally, LV early diastolic strain rate slowed from baseline to the 5h timepoint (1.19±0.35 to 0.95±0.37/s, p = 0.02) in shocked animals. Whereas no change was observed for any global strain parameters in the control group. There was no linear association with regional LV peak strain with T1 changes (p=0.97). However, an increase in T1 was colocalized to a reduction in early diastolic strain rate (p = 0.03), where early diastolic strain rate slowed by -0.25/s every 100ms increase in T1. On the other hand, both RV systolic and diastolic function worsened in the presence of increased regional RV T1 with a change in peak strain of 2.7% and a deceleration of diastolic strain rate (–0.42/s) per 100ms increase in RV T1 (p<0.05). <h3>Conclusions</h3> Serial transthoracic shock in a healthy swine model attenuate biventricular systolic function, but it is the development of regional diastolic dysfunction that is associated with the onset of colocalized myocardial edema. Future studies are warranted to assess these effects of electrical interventions in clinical settings.

Cavitation‐Associated Water Evaporation From Porous Media Through In Situ NMR Characterization

AbstractEvaporation of water from porous media is essential for a large variety of applications, whereas the opacity of porous matrix imposes considerable challenges in unveiling complicated phase‐change phenomena. Air invasion was previously reported as the major desaturation mechanism, while cavitation in porous media is not well studied. Herein we characterize the transient distribution and evaporation of water in homogeneous tight porous media with nondestructive nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). By monitoring the amplitude change of NMR transverse relaxation time T2, we investigate the dynamical pore filling status and water content during evaporation. Interestingly, we find that the T2 spectrum shifts immediately after the evaporation starts, indicating the emptying of big pores from the entire medium. Disconnected void clusters at different depths in the porous medium are also observed from MRI scanning and optical images. These observations indicate the emergence of cavitation across the entire porous media along with the evaporation from open surface. Cavitation occurs when the water is stretched to metastable state by large capillary pressure from the evaporating meniscus. By studying the evaporation from hydrophilic membrane‐separated porous media, we further demonstrate the existence of cavitation‐associated evaporation. The preferential water vaporization from the bottom part can still be found from T2 spectrum analysis and optical imaging even when the water‐permeable membrane cuts off possible air invasion. Our findings confirm cavitation‐associated evaporation is one of the primary mechanisms for tight porous media, which provides valuable guidance for evaporation and moisture control.

Associations of incidental vertebral fractures and longitudinal changes of MR-based proton density fat fraction and T2* measurements of vertebral bone marrow.

Quantitative magnetic resonance imaging (MRI) techniques such as chemical shift encoding-based water-fat separation techniques (CSE-MRI) are increasingly applied as noninvasive biomarkers to assess the biochemical composition of vertebrae. This study aims to investigate the longitudinal change of proton density fat fraction (PDFF) and T2* derived from CSE-MRI of the thoracolumbar vertebral bone marrow in patients that develop incidental vertebral compression fractures (VCFs), and whether PDFF and T2* enable the prediction of an incidental VCF. In this study we included 48 patients with CT-derived bone mineral density (BMD) measurements at baseline. Patients that presented an incidental VCF at follow up (N=12, mean age 70.5 ± 7.4 years, 5 female) were compared to controls without incidental VCF at follow up (N=36, mean age 71.1 ± 8.6 years, 15 females). All patients underwent 3T MRI, containing a significant part of the thoracolumbar spine (Th11-L4), at baseline, 6-month and 12 month follow up, including a gradient echo sequence for chemical shift encoding-based water-fat separation, from which PDFF and T2* maps were obtained. Associations between changes in PDFF, T2* and BMD measurements over 12 months and the group (incidental VCF vs. no VCF) were assessed using multivariable regression models. Mixed-effect regression models were used to test if there is a difference in the rate of change in PDFF, T2* and BMD between patients with and without incidental VCF. Prior to the occurrence of an incidental VCF, PDFF in vertebrae increased in the VCF group (ΔPDFF=6.3 ± 3.1%) and was significantly higher than the change of PDFF in the group without VCF (ΔPDFF=2.1 ± 2.5%, P=0.03). There was no significant change in T2* (ΔT2*=1.7 ± 1.1ms vs. ΔT2*=1.1 ± 1.3ms, P=0.31) and BMD (ΔBMD=-1.2 ± 11.3mg/cm3 vs. ΔBMD=-11.4 ± 24.1mg/cm3, P= 0.37) between the two groups over 12 months. At baseline, no significant differences were detected in the average PDFF, T2* and BMD of all measured vertebrae (Th11-L4) between the VCF group and the group without VCF (P=0.66, P=0.35 and P= 0.21, respectively). When assessing the differences in rates of change, there was a significant change in slope for PDFF (2.32 per 6 months, 95% confidence interval (CI) 0.31-4.32; P=0.03) but not for T2* (0.02 per 6 months, CI -0.98-0.95; P=0.90) or BMD (-4.84 per 6 months, CI -23.4-13.7; P=0.60). In our study population, the average change of PDFF over 12 months is significantly higher in patients that develop incidental fractures at 12-month follow up compared to patients without incidental VCF, while T2* and BMD show no significant changes prior to the occurrence of the incidental vertebral fractures. Therefore, a longitudinal increase in bone marrow PDFF may be predictive for vertebral compression fractures.

Unloader bracing in osteoarthritis of the knee – Is there a direct effect on the damaged cartilage?

BackgroundUnloading knee braces represent a conservative treatment option for non-pharmalogical management of unicompartmental osteoarthritis of the knee. Though there is consensus on the clinical effectiveness of unloading, the effect mechanism of bracing remains part of a debate. Our study was designed to assess the effect of unloader bracing on damaged cartilage via MRI cartilage mappings. MethodsFourteen patients (7 female, 7 male, mean age 43.1 ± 9.4 years) with unicompartmental cartilage wear in knees with varus or valgus malalignment were enrolled. Clinical scores, radiographs and MR-graphic properties (T2/T2* mapping, T1 Delayed Gadolinium Enhanced MRI of the cartilage (dGEMRIC) mapping, high-resolution PDw sequences) of knee cartilage were recorded before and three months after brace use. ResultsBracing the knees for a mean of 14.4 ± 2.0 weeks (range 11 to 18 weeks) resulted in significant pain reduction (VAS changed from 5.9 ± 2.0 to 2.0 ± 1.3, p < 0.001) and improvement in knee function (KOOS increased from 42.1 ± 22.7 to 64.8 ± 18.7, p < 0.001). In the affected cartilage regions T2 relaxation times significantly decreased from 56.1 ± 11.4 ms to 46.5 ± 11.2 ms (p < 0.05). No changes in T1-dGEMRIC and T2* relaxation times, thickness or the extent of the damaged cartilage area could be detected. ConclusionsOur results suggest, that unloader bracing improves the biochemical properties of the damaged cartilage by increasing collagen and proteoglycan concentration as well as decreasing the cartilage edema.

Hyperpolarized Metabolic and Parametric CMR Imaging of Longitudinal Metabolic-Structural Changes in Experimental Chronic Infarction

BackgroundProlonged ischemia and myocardial infarction are followed by a series of dynamic processes that determine the fate of the affected myocardium toward recovery or necrosis. Metabolic adaptions are considered to play a vital role in the recovery of salvageable myocardium in the context of stunned and hibernating myocardium. ObjectivesThe potential of hyperpolarized pyruvate cardiac magnetic resonance (CMR) alongside functional and parametric CMR as a tool to study the complex metabolic-structural interplay in a longitudinal study of chronic myocardial infarction in an experimental pig model is investigated. MethodsMetabolic imaging using hyperpolarized [1-13C] pyruvate and proton-based CMR including cine, T1/T2 relaxometry, dynamic contrast-enhanced, and late gadolinium enhanced imaging were performed on clinical 3.0-T and 1.5-T MR systems before infarction and at 6 days and 5 and 9 weeks postinfarction in a longitudinal study design. Chronic myocardial infarction in pigs was induced using catheter-based occlusion and compared with healthy controls. ResultsMetabolic image data revealed temporarily elevated lactate-to-bicarbonate ratios at day 6 in the infarcted relative to remote myocardium. The temporal changes of lactate-to-bicarbonate ratios were found to correlate with changes in T2 and impaired local contractility. Assessment of pyruvate dehydrogenase flux via the hyperpolarized [13C] bicarbonate signal revealed recovery of aerobic cellular respiration in the hibernating myocardium, which correlated with recovery of local radial strain. ConclusionsThis study demonstrates the potential of hyperpolarized CMR to longitudinally detect metabolic changes after cardiac infarction over days to weeks. Viable myocardium in the area at risk was identified based on restored pyruvate dehydrogenase flux.

RADT-42. EFFECTS OF RADIOTHERAPY FOR CNS NEOPLASMS IN PEOPLE WITH MULTIPLE SCLEROSIS

Abstract INTRODUCTION Patients with multiple sclerosis (MS) may be at higher risk of brain tumors (Khalil 2012, London 2020, etc.). However, MS patients have been reported to have adverse effects from radiotherapy, a mainstay of CNS treatment. In the last ten years, radiation techniques have improved. We submit a case report of an MS patient with demyelinating CNS lesions shortly after radiation therapy for an astrocytoma and review the literature. Case description: A 40-year-old woman with a history of MS treated with Siponimod underwent resection of a right frontotemporal grade 2 astrocytoma, IDH mutant. She received adjuvant proton radiotherapy (54 Gy(RBE) over 30 fractions) followed by temozolomide chemotherapy. She tolerated radiotherapy well and only experienced grade 1 dermatitis, fatigue, and hair loss within the field of treatment. 1-month post radiation MRI was stable. 4 months post radiation there was an asymptomatic new typical demyelinating lesion on FLAIR without T1 or contrast changes. This was outside the high dose radiation field (i.e. received ~30 Gy(RBE)). Her Siponimod had been held for concerns of interactions with radiation or chemotherapy. DISCUSSION Cases have been reported of people with MS experiencing adverse effects from radiotherapy. Murphy, et al., reported a 30-year-old woman with MS experiencing an attack of demyelination 2 months after radiotherapy (50 Gy over 25 fractions), and Borges, et al. presents a 28-year-old patient who experienced radiotherapy-induced inflammatory demyelination after receiving whole-ventricular irradiation (24 Gy over 15 fractions). Miller, et al., reported 6 patients without exacerbations of MS but had developed grade 4 neurotoxicity in a median of 1 year; most of those patients were treated with older radiation techniques, however. Radiotherapy effects in people with MS is a topic that should be revisited in the era of more conformal RT techniques, effective MS therapies, and cancer treatment including immunotherapy.

In vivo T1 mapping of neonatal brain tissue at 64 mT.

Ultralow-field (ULF) point-of-care MRI systems allow image acquisition without interrupting medical provision, with neonatal clinical care being an important potential application. The ability to measure neonatal brain tissue T1 is a key enabling technology for subsequent structural image contrast optimization, as well as being a potential biomarker for brain development. Here we describe an optimized strategy for neonatal T1 mapping at ULF. Examinations were performed on a 64-mT portable MRI system. A phantom validation experiment was performed, and a total of 33 in vivo exams were acquired from 28 neonates with postmenstrual age ranging from 31+4 to 49+0 weeks. Multiple inversion-recovery turbo spin-echo sequences were acquired with differing inversion and repetition times. An analysis pipeline incorporating inter-sequence motion correction generated proton density and T1 maps. Regions of interest were placed in the cerebral deep gray matter, frontal white matter, and cerebellum. Weighted linear regression was used to predict T1 as a function of postmenstrual age. Reduction of T1 with postmenstrual age is observed in all measured brain tissue; the change in T1 per week and 95% confidence intervals is given by dT1 =-21 ms/week [-25, -16] (cerebellum), dT1 =-14 ms/week [-18, -10] (deep gray matter), and dT1 =-35 ms/week [-45, -25] (white matter). Neonatal T1 values at ULF are shorter than those previously described at standard clinical field strengths, but longer than those of adults at ULF. T1 reduces with postmenstrual age and is therefore a candidate biomarker for perinatal brain development.

Cytoskeletal protein breakdown and serum albumin extravasation in MRI DWI-T2WI mismatch area in acute murine cerebral ischemia

MRI diffusion-weighted imaging (DWI)-FLAIR mismatch is known as predictive of symptom onset within 4.5 h. This study assessed the breakdown of cytoskeletal protein and blood-brain barrier (BBB) in DWI-T2 mismatch. We employed occlusion of middle cerebral artery (MCAO) in C57BL/6 mice. We serially measured MRI including DWI and T2WI. After MRI, we prepared brain sections or samples and examined microtubule-associated protein 2 (MAP2) expression, alpha-fodrin degradation, extravasation of albumin and claudin-5 expression. In permanent or transient MCAO for 45 min, DWI hyperintensities was already found at 60 min without change of T2, showing DWI-T2 mismatch. In permanent MCAO, MAP2 expressions were preserved, and no extravasation of albumin was observed. In transient MCAO, MAP2 immunoreaction was already lost in the lateral part of the striatum. In both models, alpha-fodrin degradation was already detected. At 180 min, T2 hyperintensities appeared, where MAP2 signal was lost and albumin extravasation was found. At 24 h, hyperintensities of DWI and T2WI was found in the whole MCA territory, where MAP2 signal was completely lost with marked albumin extravasation and alpha-fodrin degradation. Immunoreaction for claudin-5 was preserved up to 180 min. DWI-T2 mismatch area may not always indicate intactness of cytoskeletal protein but shows preservation of BBB.