Marie Wasielewski

Cardiac Magnetic Resonance T2 Mapping in the Monitoring and Follow-up of Acute Cardiac Transplant Rejection A Pilot Study

Background—Acute rejection is a major factor impacting survival in the first 12 months after cardiac transplantation. Transplant monitoring requires invasive techniques. Cardiac magnetic resonance (CMR), noninvasive testing, has been used in monitoring heart transplants. Prolonged T2 relaxation has been related to transplant edema and possibly rejection. We hypothesize that prolonged T2 reflects transplant rejection and that quantitative T2 mapping will concur with the pathological and clinical findings of acute rejection. Methods and Results—Patients were recruited within the first year after transplantation. Biopsies were graded according to the International Society for Heart Lung Transplant system for cellular rejection with immunohistochemistry for humoral rejection. Rejection was also considered if patients presented with signs and symptoms of hemodynamic compromise without biopsy evidence of rejection who subsequently improved with treatment. Patients underwent a novel single-shot T2-prepared steady-state free precession 4-chamber and 3 short axis sequences and regions of interest were drawn overlying T2 maps by 2 independent blinded reviewers. A total of 74 (68 analyzable) CMRs T2 maps in 53 patients were performed. There were 4 cellular, 2 humoral, and 2 hemodynamic rejection cases. The average T2 relaxation time for grade 0R (n=46) and grade 1R (n=17) was 52.5±2.2 and 53.1±3.3 ms (mean±SD), respectively. The average T2 relaxation for grade 2R (n=3) was 59.6±3.1 ms and 3R (n=1) was 60.3 ms (all P value <0.05 compared with controls). The T2 average in humoral rejection cases (n=2) was 59.2±3.3 ms and the hemodynamic rejection (n=2) was 61.1±1.8 ms (P<0.05 versus controls). The average T2 relaxation time for all-cause rejection versus no rejection is 60.1±2.1 versus 52.8±2.7 ms (P<0.05). All rejection cases were rescanned 2.5 months after treatment and demonstrated T2 normalization with average of 51.4±1.6 ms. No difference was found in ventricular function between nonrejection and rejection patients, except in ventricular mass 107.8±10.3 versus 127.5±10.4 g (P < 0.05). Conclusions—Quantitative T2 mapping offers a novel noninvasive tool for transplant monitoring, and these initial findings suggest potential use in characterizing rejections. Given the limited numbers, a larger multi-institution study may help elucidate the benefits of T2 mapping as an adjunctive tool in routine monitoring of cardiac transplants.

Three-dimensional hemodynamics in intracranial aneurysms: Influence of size and morphology

To use four‐dimensional (4D)‐flow MRI for the comprehensive in vivo analysis of hemodynamics and its relationship to size and morphology of different intracranial aneurysms (IA). We hypothesize that different IA groups, defined by size and morphology, exhibit different velocity fields, wall shear stress, and vorticity.

3D Hemodynamics in Intracranial Aneurysms: Influence of Size and Morphology

To use four‐dimensional (4D)‐flow MRI for the comprehensive in vivo analysis of hemodynamics and its relationship to size and morphology of different intracranial aneurysms (IA). We hypothesize that different IA groups, defined by size and morphology, exhibit different velocity fields, wall shear stress, and vorticity.

Clinical utility of cardiac magnetic resonance T2 mapping for acute myocardial edema

Objective To evaluate the potential clinical utility of T2 quantitative mapping for myocardial edema in acute disease pathology - myocarditis, myocardial infarction, TakoTsubo cardiomyopathy, and transplant rejection. Background Edema is ag eneric tissue response to acute myocardial injury and, therefore; a potential marker of impending tissue damage. Currently in clinical use, T2 weighted imaging provides a qualitative technique in assessing myocardial edema. We hypothesize that quantitative T2 mapping in patients with suspected cases of myocarditis, myocardial infarction (AMI), and cardiac transplant rejection will provide a more sensitive and specific diagnostic prediction than with T2W imaging, and add to other imaging techniques. Method

Potential associations between chronic whiplash and incomplete spinal cord injury

Study Design:This research utilized a cross-sectional design with control group inclusion.Objectives:Preliminary evidence suggests that a portion of the patient population with chronic whiplash may have sustained spinal cord damage. Our hypothesis is that in some cases of chronic whiplash-associated disorders (WAD), observed muscle weakness in the legs will be associated with local signs of a partial spinal cord injury of the cervical spine.Setting:University based laboratory in Chicago, IL, USA.Methods:Five participants with chronic WAD were compared with five gender/age/height/weight/body mass index (BMI) control participants. For a secondary investigation, the chronic WAD group was compared with five unmatched participants with motor incomplete spinal cord injury (iSCI). Spinal cord motor tract integrity was assessed using magnetization transfer imaging. Muscle fat infiltration (MFI) was quantified using fat/water separation magnetic resonance imaging. Central volitional muscle activation of the plantarflexors was assessed using a burst superimposition technique.Results:We found reduced spinal cord motor tract integrity, increased MFI of the neck and lower extremity muscles and significantly impaired voluntary plantarflexor muscle activation in five participants with chronic WAD. The lower extremity structural changes and volitional weakness in chronic WAD were comparable to participants with iSCI.Conclusion:The results support the position that a subset of the chronic whiplash population may have sustained partial damage to the spinal cord.Sponsorship:NIH R01HD079076-01A1, NIH T32 HD057845 and the Foundation for Physical Therapy Promotion of Doctoral Studies program.

MR-derived right ventricular parameters can predict pulmonary hypertension

Right heart catheterization (RHC) is required for definitive diagnosis of pulmonary hypertension (PH) and serial echocardiograms or RHC are necessary for long term disease management. However, RHC is invasive, costly and risky for the patient[1]. Echocardiography is a non-invasive alternative but recent studies have questioned its accuracy and reproducibility in the setting of PH[2]. Cardiac magnetic resonance (CMR) has been shown to be helpful in distinguishing PH patients from healthy subjects through visualization of morphologic features such as right atrial and ventricular enlargement, tricuspid regurgitation and abnormal interventricular septal motion[3]. CMR has the additional advantage of producing quantitative measures of right ventricular function, which may have added value in assessing PH.

Ambulatory function in motor incomplete spinal cord injury: a magnetic resonance imaging study of spinal cord edema and lower extremity muscle morphometry

Study design:This research utilized a cross-sectional design.Objectives:Spinal cord edema length has been measured with T2-weighted sagittal MRI to predict motor recovery following spinal cord injury. The purpose of our study was to establish the correlational value of axial spinal cord edema using T2-weighted MRI. We hypothesized a direct relationship between the size of damage on axial MRI and walking ability, motor function and distal muscle changes seen in motor incomplete spinal cord injury (iSCI).Setting:University-based laboratory in Chicago, IL, USA.Methods:Fourteen participants with iSCI took part in the study. Spinal cord axial damage ratios were assessed using axial T2-weighted MRI. Walking ability was investigated using the 6-min walk test and daily stride counts. Maximum plantarflexion torque was quantified using isometric dynomometry. Muscle fat infiltration (MFI) and relative muscle cross-sectional area (rmCSA) were quantified using fat/water separation magnetic resonance imaging.Results:Damage ratios were negatively correlated with distance walked in 6 min, average daily strides and maximum plantarflexion torque, and a negative linear trend was found between damage ratios and lower leg rmCSA. While damage ratios were not significantly correlated with MFI, we found significantly higher MFI in the wheelchair user participant group compared to community walkers.Conclusions:Damage ratios may be useful in prognosis of motor recovery in spinal cord injury. The results warrant a large multi-site research study to investigate the value of high-resolution axial T2-weighted imaging to predict walking recovery following motor incomplete spinal cord injury.

Lower extremity muscle structure in incomplete spinal cord injury: a comparison between ultrasonography and magnetic resonance imaging

Introduction:Ultrasound (US) measures of muscle thickness are used in the management and monitoring of muscle changes during rehabilitation, but it is unknown how this measure compares to magnetic resonance imaging (MRI) measures of muscle cross-sectional area (CSA) in patients with spinal cord injury (SCI).Case Presentation:Six participants with incomplete SCI underwent US imaging and MRI of their gastrocnemius and tibialis anterior (TA) muscles.Discussion:Significant correlations were found between US muscle thickness and MRI CSA in the gastrocnemius (R=0.91, P<0.001), and TA muscles (R=0.58, P<0.05). US muscle thickness in the gastrocnemius and TA of patients with incomplete SCI may be used as a cheaper alternative measure of CSA as measured using MRI, and this measure may be clinically useful to track progress in muscle gains during rehabilitation.

Lateral Corticospinal Tract Damage Correlates With Motor Output in Incomplete Spinal Cord Injury

OBJECTIVE To investigate the relationship between spinal cord damage and specific motor function in participants with incomplete spinal cord injury (iSCI). DESIGN Single-blinded, cross-sectional study design. SETTING University setting research laboratory. PARTICIPANTS Individuals with chronic cervical iSCI (N=14; 1 woman, 13 men; average age ± SD, 43±12y). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Axial T2-weighted magnetic resonance imaging (MRI) of spinal cord damage was performed in 14 participants with iSCI. Each participants damage was processed for total damage quantification, lateral corticospinal tract (LCST) and gracile fasciculus (GF) analysis. Plantarflexion and knee extension were quantified using an isokinetic dynamometer. Walking ability was assessed using a 6-minute walk test. RESULTS Total damage was correlated with plantarflexion, knee extension, and distance walked in 6 minutes. Right LCST damage was correlated with right plantarflexion and right knee extension, while left LCST damage was correlated with left-sided measures. Right and left GF damage was not correlated with the motor output measures. CONCLUSIONS MRI measures of spinal cord damage were correlated to motor function, and this measure appears to have spatial specificity to descending tracts, which may offer prognostic value after SCI.

Biventricular strain analysis at 1.5T cardiac MR imaging: preliminary results in volunteers using an iterative SENSE reconstruction with L1 regularization

Background Changes in myocardial strain have been shown to precede onset of systolic dysfunction in patients with cardiomyopathy. Traditionally performed with echocardiography, acoustic windows can limit strain evaluation. Preliminary work has shown good agreement between myocardial strain derived from deformation field analysis at balanced steady-state free-precession (bSSFP) cine MRI and speckle tracking echocardiography. The application of a novel prototype iterative SENSE reconstruction with L1 regularization (IRSENSE) to highly accelerated segmented bSSFP cine acquisitions can maintain or improve the effective temporal resolution with a shorter breath-hold. The purpose of this study is to evaluate left- and right-ventricular stain analysis from bSSFP cine acquisitions using conventional GRAPPA and highly accelerated T-PAT with IR-SENSE. We hypothesize that myocardial strain parameters derived from accelerated T-PAT cine acquisitions with IR-SENSE are similar to those obtained using conventional segmented bSSFP with comparable effective temporal resolutions.