Keywords: Bone, Diabetes

Motivation: Bone marrow is a key target for diabetes mellitus.

Goal(s): Quantitative assessment of fat content in lumbar bone marrow and trabecular microstructural changes in alloxan-induced diabetics rabbits.

Approach: Iterative decomposition of water and fat with echo asymmetry and least-squares estimation quantitation sequence (IDEAL-IQ), micro computed tomography (Micro-CT), and gas chromatography-mass spectrometry (GC-MS) were employed.

Results:  IDEAL-IQ and GC-MS techniques are capable of detecting changes in fat content and variations in fatty acid composition during the early stages of diabetic bone marrow.

Impact: The fat content and fatty acid composition in the bone marrow plays an important role in bone metabolism in diabetic patients.

Keywords: Muscle, Relaxometry, T2 mapping

Motivation: Current  clinical use of quantitative MRI biomarkers for the assessment of neuromuscular disease is limited by accuracy and reliability

Goal(s): To develop a robust processing strategy for multi-vendor muscle-water T₂ mapping (T_2m) in foot muscle

Approach: A multi-component CPMG extended phase graph signal model was used to determine T_2m and apparent fat fraction (ff_a) in fat-infiltrated foot muscle using maximum likelihood estimation

Results: Stable estimates of foot muscle T_2m and ff_a were obtained in patients with Charcot-Marie-Tooth disease and healthy controls, at baseline and 1 year follow up. In patients, T_2m and ff_a were both elevated at each time point

Impact: T_2m and ff_a obtained from CPMG images using extended phase graph modelling and maximum likelihood estimation may be sensitive measures of neuromuscular pathology

Keywords: Cartilage, Cartilage

Motivation: Preclinical measurement series of articular cartilage samples are often time-consuming. Thus, knowledge about changes in relaxation properties of cartilage during measurements and depending on the sample handling is important.

Goal(s): To study the effect of storage temperature and immersion liquid on the relaxation properties of articular cartilage.

Approach: T1, T2, and adiabatic T1rho relaxation times were measured for 28 cartilage-bone samples at five timepoints and analyzed by linear regression.

Results: T1 and adiabatic T1rho relaxation times increased over time, while T2 varied. Immersion in phosphate-buffered saline instead of signal-free perfluoropolyether increased the relaxation times in superficial cartilage.

Impact: The study increases understanding on how the relaxation properties within ex vivo cartilage samples change over time. The results obtained here should be considered when planning future studies utilizing such samples.

Keywords: Bone, Data Analysis, Spine

Motivation: Modic Changes (MCs) are often heterogeneous and difficult to classify objectively. Hence, new diagnostic tools are required to improve MC classification.

Goal(s): This study aims to develop a data-driven model for the classification of MC lesions on a per-lesion and per-voxel level from conventional MR images.

Approach: Conventional MR images from 12 patients were used to create an MC classification model by fitting three multivariate normal distribution functions to the MRI MC data which was subsequently used for MC classification. 

Results: The model reached high accuracy (74-100%), enabling a detailed classification on a per-voxel level and longitudinal tracking of MC transitions.

Impact: This study introduces a data-driven model for classifying Modic changes in vertebral bone marrow using MR images. The model achieves high accuracy, enabling detailed classification and tracking of Modic change transitions, potentially improving patient diagnosis and care.

Keywords: Muscle, Muscle, Quantitative Imaging

Motivation: The overall aim of our ongoing study MOTION is to connect whole leg quantitative MRI (qMRI) and muscle structure to function and lifestyle in 162 healthy volunteers.

Goal(s): Preliminary analysis of 31 subjects to identify potential covariates that may impact qMRI measurements.

Approach: Muscle fat fraction (FF), mean diffusivity (MD), fractional anisotropy (FA) and T2_water were determined in 20 muscles from tendon to tendon bilaterally, and related to age, gender, and body composition.

Results:  Muscle FF is higher in heavier subjects with more body fat. FA is lower and MD and volume are higher in larger subjects. T2_water depends on age and gender.     

Impact: Accounting for covariates describing body composition (BMI, lean body mass and body fat mass) on top of gender and age is crucial for proper interpretation of quantitative muscle MRI in clinical studies on neuromuscular disease patients and healthy controls.

Keywords: Muscle, Modelling, biomarkers, neuromuscular, water T2, fat fraction

Motivation: Muscle water T₂ is an interesting quantitative MRI biomarker in neuromuscular disorders but its interpretation is influenced by the presence of fat.

Goal(s): We investigated how this water T₂-fat relationship differed between nine different neuromuscular disorders.

Approach: We looked at linear and 2^nd degree polynomial fits, all obtained with the same 3-T system, sequence and post-processing pipeline.

Results: Polynomial fitting describes the data better and the water T₂-fat relationship needs to be interpreted in a disease-specific context, especially when there is a known inflammatory component and/or if water T₂ is increased before the occurrence of any muscle fat replacement.

Impact: The relationship between MRI biomarkers water T2, reflecting active muscle damage, and fat fraction, reflecting disease progression, should be interpreted in the context of the disease, whether or not there is inflammation or extensive active muscle damage.

Keywords: Skeletal, Skeletal

Motivation: It is common for patients with primary tumors to find abnormal signals in the spine, which may be initially reported as “metastases cannot be rule out”. For these cases, differential diagnosis has a significant impact on patient staging and management, which may result in misdiagnosis or additional imaging, ultimately biopsy, and unnecessary costs.

Goal(s): To investigate chemical shift-encoded sequence (IDEAL-IQ) for differential diagnosis of spinal tumors.

Approach: Single-center prospective study.

Results: This work highlights the benefits of adding proton density fat fraction (PDFF) maps yield from IDEAL-IQ to improve diagnostic accuracy of spinal metastases and hemangiomas without contrast agents.

Impact: IDEAL-IQ provides reliable quantification of spinal tumor bone marrow infiltration pattern in clinical settings, which is comparable to the quantitative parameters of DCE-MRI. It may be a valuable tool for providing information for early differential diagnosis in a non-invasive way.

Keywords: Bone, Bone, UTE, Knee, Osteoarthritis

Motivation: Bony structures of the human knee play import roles in the stability and normal function and show alterations in morphology with diseases such as osteoarthritis.

Goal(s): Advance MR imaging of the bone.

Approach: Three techniques utilizing delta ultrashort echo time (𝛅UTE), field echo (FE), and FE with deep learning reconstruction (DLR) with simple post-processing was developed to image knees of volunteers. SNR and CNR were determined.

Results: We demonstrate that FE DLR, compared to 𝛅UTE, was advantageous for greater signal to noise ratio for the cortical bone, as well as higher resolution that depicted trabecular structures.

Impact: This study advances MR imaging of the bone, for specific use cases such as morphologic evaluation. The FE technique in particular is immediately translatable using existing sequences to help evaluate knee bone in the clinical settings. 

Keywords: Other Musculoskeletal, Fat, Fat Suppression, Dixon

Motivation: The use of 2-point Dixon is prevalent for fat/water separation in MRI, but suffers from incomplete fat suppression, leading to residual fat signal in the water image. We have previously developed a “Darkfat” post-processing technique that can reduce this residual signal.

Goal(s): This retrospective study aims to evaluate Darkfat processing in clinical lumbar plexus images.

Approach: Retrospective 2-point T2-weighted lumbar images from 30 patients were processed using Darkfat and evaluated through qualitative and quantitative assessment.

Results: Water-only images from Darkfat processing had significantly better fat suppression (P<0.0001), and subjectively better image quality (P<0.005) compared to original water images from 2-point T2-weighted Dixon acquisition.

Impact: Darkfat image processing significantly improves fat suppression in clinical 2-point T2-weighted lumbar images enabling enhanced anatomical visualization. This could potentially improve pathological visualization.

Keywords: Cartilage, Joints, UTE-QSM

Motivation: Quantitative susceptibility mapping (QSM) may be a useful tool for studying the characteristics of collagen fibers in knee cartilage.The susceptibility quantification using GRE with fat saturation and relatively long TE may be further improved using UTE-QSM.

Goal(s): To measure the change in susceptibility values of knee cartilage in patients with different grades of OA using UTE-QSM.

Approach: A total of 13 knees from 10 patients who underwent both X-ray and MRI-UTE  were enrolled.

Results: Our results show that in the posterior regions of the medial femoral condyle and lateral femoral condyle, the magnetic susceptibility value significantly decreases with the increase of OA grade.

Impact: UTE-QSM can promote osteoarthrologists and radiologists to better understand knee OA from different dimensions, and can provide more imaging evidence for monitoring the progress of OA, formulating treatment plans, and evaluating treatment effects.

Keywords: Cartilage, Software Tools

Motivation: To address the global healthcare challenge of knee osteoarthritis.

Goal(s): Develop and validate an automated post-processing method for quantitative 3D T1ρ knee imaging analysis.  The proposed post-processing pipeline accelerates the process while preserving a user-friendly and clinical-related output.

Approach: We proposed a post-processing pipeline that combines parcellation, ROIs selection, T1rho fitting, and regionally averaged outputs. We evaluated our approach on 30 OA patients and 10 healthy controls. 

Results: The proposed post-processing approach achieved satisfactory performance on automatic ROI selection compared to the manually labelled ROIs and provided quantitative T1ρ analysis with clinical promise. 

Impact: Our proposed pipeline enables automated post-processing for T1ρ imaging with deep learning, pushing this promising technique to the clinics to provide sensitive and quantitative knee OA diagnostics.

Keywords: Cartilage, Quantitative Imaging

Motivation: T2 mapping is difficult to be implemented in clinics for long scan time. 

Goal(s): To propose a 10-minute fast spin echo knee MRI protocol including quantitative T2 map and morphologic images in identifying cartilage injury or grading cartilage degeneration.

Approach: To subjectively and objectively assess the clinical value of knee imaging with different acceleration factor of 2 and 3 as well as using conventional and deep learning reconstruction algorithms (CR, DLR). 

Results: Both FSE_DLR and DL-based quantitative T2 map with either an acceleration factor of 2 or 3 elevated diagnostic accuracy using a senior rater as a final diagnosis. 

Impact: A knee protocol including deep-learning based FSE structure imaging and quantitative T2 map could be facilitated in clinical application further elevating the diagnostic accuracy and performance.

Keywords: Muscle, Aging

Motivation: There is a need to investigate the relationship between age-related muscle atrophy and functional strength.  

Goal(s): To explore the relationship between volumes of individual knee extensor muscles relative to total volume of the quadriceps as measured by MRI and sit to stand performance.

Approach: Participants performed a sit to stand test while being recorded by a markerless motion capture system and underwent an MRI exam that included a Dixon scan, which was used to calculate muscle volumes in the quadriceps.  

Results: There were correlations between age and vastus intermedius and vastus lateralis volume.  Rectus femoris volume was correlated with sit to stand performance.  

Impact: We utilized a novel experimental design using smartphone-based markerless motion capture and MRI metrics to study the relationship between functional strength and age-related muscle atrophy.  This work could inform design of physical therapy programs for the elderly.  

Keywords: Muscle, Data Analysis

Motivation: To explore the influence of erector spinae muscle asymmetry to adult degenerative scoliosis (ADS) on patients' quality of life.

Goal(s): To develop a pipeline for automated quantification of the normalized FCSA difference index (CDI) and left-right fat Infiltration asymmetry ratio (LFIAR) from MRI images for assessment of ADS.

Approach: We used nnU-Net for precise anatomical segmentation on T2 images. Then, CDI and LFIAR were calculated and correlated to ADS scales.

Results: The automated model adeptly delineated paravertebral muscle groups, which were used to calculate CDI and LFIAR. Noteworthy correlations between CDI, LFIAR, and ADS scales were found among male subjects.

Impact: This research streamlines clinical workflows, imparts valuable insights into the severity of ADS, and equips clinicians with crucial data for informed clinical decision-making.

Keywords: Skeletal, Skeletal, Scoliosis, MSK, Spine, sCT, synthetic CT

Motivation: To date, there is no description of an optimal MRI protocol for detection of early changes in the scoliotic spine.

Goal(s): The goal is to assess the feasibility of the multi-purpose short MRI protocol based on the MR data of adult volunteers.

Approach: Based on the checklist of relevant landmarks, assessment of the volunteer MR data and identification of the landmarks was performed by 3 readers.

Results: We have demonstrated that the proposed MRI protocol, covering almost the entire spine in 14 min, is efficient for detection of relevant landmarks for: scoliosis assessment, screening for neural axis abnormalities, and surgical planning and navigation.

Impact: A short MRI protocol is developed for accurate assessment of spinal deformity in AIS patients, facilitating the treatment management, monitoring and surgical planning, and simplifying the clinical workflow.

Keywords: Muscle, Aging

Motivation: The evaluation of extracellular matrix levels in skeletal muscle often requires tissue biopsy, which is difficult for patients to accept in clinical practice

Goal(s): We evaluated the extracellular matrix level of skeletal muscle using non-invasive magnetic resonance imaging technology and conducted pathological verification using skeletal muscle samples from rats with sarcopenia

Approach: We constructed a classic sarcopenic  rat model , scanned the lumbar paravertebral muscles with a 3.0T MRI-based DTI sequence, and validated through histological experiments

Results: FA and CSA of sarcopenic rats were significantly reduced compared to the normal control group, and there was a strong correlation between them and pathological related parameters

Impact: Our study provides a non-invasive tool for evaluating the extracellular matrix levels of skeletal muscles in sarcopenia

Keywords: Muscle, Aging

Motivation: The exercise-tailored diffusion-weighted imaging (DWI) protocol has never been implemented to assess sex differences in age-related muscle quality in the healthy population.

Goal(s): To investigate the feasibility of muscle kinetics on DWI during exercise for assessing sex differences in age-related muscle quality.

Approach: This study recruited 87 healthy participants with 174 legs imaged and assessed muscle kinetics on DWI during exercise for assessing sex differences in age-related muscle quality.

Results: Males and females showed different age-related pattern with  muscle kinetics on DWI during plantar flexion.

Impact: An exercise-tailored MR protocol can be implemented for assessing the muscle quality. 

Keywords: Cartilage, Artifacts

Motivation: Knee joint MRI requires m sequences involving multiple planes and with- and without fat suppression, which is time-consuming.

Goal(s): Provides detailed cartilage and ligament information in a short period of time and allows multiplanar reconstruction in any plane of any thickness from a single high-resolution isotropic imaging.

Approach: CS-AI 3D mDixon TSE images were compared with conventional SENSE and CS images.

Results: It indicated that 3D mDixon CS-AI can provide more accurate image information of cartilage and ligaments with high reproducibility and robustness.

Impact: This technique may be helpful to further assess knee pathology.

Keywords: Muscle, Spectroscopy, Skeletal muscle metabolism

Motivation: ³¹P-MRS  methodology is notoriously laboratory-specific, leading to uncertainty about the normal range of PCr recovery kinetics among healthy individuals, as well correlations with disease and demographic factors.

Goal(s): Our aim was to characterize the normal range of PCr recovery measurements from ³¹P-MRS in human skeletal muscles, as well as correlations with age and end-of-exercise pH.

Approach: Included studies focused on exercise-induced skeletal muscle PCr recovery kinetics in healthy or diseased individuals, using 31P-MRS.

Results: PCr recovery time is consistent across three skeletal muscle groups in healthy individuals from diverse MRI centers. Greater age and more acidic pH increase PCr recovery time.

Impact: These results will set the indexes for PCr recovery kinetic measures across different human skeletal muscles.  

Keywords: Bone, MSK, ZTE

Motivation: Exploring non-ionizing radiation alternatives to CT examination for diagnosing bone diseases in children is clinically desirable.

Goal(s): To compare the visualization of the bone cortex around ankle joints of adolescent pig between 3D-ZTE MRI and CT techniques. 

Approach: A total of 12 specimens were subjected to both 3D-ZTE MRI and CT examination. The thicknesses of bone cortex were measured and compared between MRI and CT images.

Results: There was no significant difference in the thicknesses of bone cortex in the inner and outer sides of tibia, fibula, and talus between 3D-ZTE and CT. 

Impact: 3D-ZTE technique can obtain CT-like images that accurately measure the thickness of bone cortex without ionizing radiation. This technique holds the potential for clinical applications in children with bone diseases, providing a safe alternative to traditional CT imaging.