The prevalence of femoroacetabular impingement anatomy in Division 1 aquatic athletes who tread water

Abstract Femoroacetabular impingement (FAI) is a disorder that causes hip pain and disability in young patients, particularly athletes. Increased stress on the hip during development has been associated with increased risk of cam morphology. The specific forces involved are unclear, but may be due to continued rotational motion, like the eggbeater kick. The goal of this prospective cohort study was to use magnetic resonance imaging (MRI) to identify the prevalence of FAI anatomy in athletes who tread water and compare it to the literature on other sports. With university IRB approval, 20 Division 1 water polo players and synchronized swimmers (15 female, 5 male), ages 18–23 years (mean age 20.7 ± 1.4), completed the 33-item International Hip Outcome Tool and underwent non-contrast MRI scans of both hips using a 3 Tesla scanner. Recruitment was based on sport, with both symptomatic and asymptomatic individuals included. Cam and pincer morphology were identified. The Wilcoxon Signed-Rank/Rank Sum tests were used to assess outcomes. Seventy per cent (14/20) of subjects reported pain in their hips yet only 15% (3/20) sought clinical evaluation. Cam morphology was present in 67.5% (27/40) of hips, while 22.5% (9/40) demonstrated pincer morphology. The prevalence of cam morphology in water polo players and synchronized swimmers is greater than that reported for the general population and at a similar level as some other sports. From a clinical perspective, acknowledgment of the high prevalence of cam morphology in water polo players and synchronized swimmers should be considered when these athletes present with hip pain

Standardized multi-vendor compositional MRI of knee cartilage: A key step towards clinical translation?

Cartilage compositional magnetic resonance imaging (MRI) techniques are sensitive to changes in the composition of the extracellular matrix of articular cartilage. Their promise lies in the potential to detect the earliest stages of cartilage degeneration, at a stage where these changes may still be reversible. This is a considerable advantage over conventional (structural) MRI; even with the high spatial-resolution imaging offered by modern high-field (3T) MRI systems, by the time structural cartilage damage is apparent, there is (by definition) damage to the collagen matrix implying that the changes are probably already irreversible

Effects of dynamic [18F]NaF PET scan duration on kinetic uptake parameters in the knee

IntroductionAccurately estimating bone perfusion and metabolism using [18F]NaF kinetics from shorter scan times could help address concerns related to patient comfort, motion, and throughput for PET scans. We examined the impact of changing the PET scan duration on the accuracy of [18F]NaF kinetic parameters in the knee.MethodsBoth knees of twenty participants with and without osteoarthritis were scanned using a hybrid PET-MRI system (53 ± 13 years, BMI 25.9 ± 4.2 kg/m2, 13 female). Seventeen participants were scanned for 54 ± 2 min, and an additional three participants were scanned for 75 min. Patlak Ki and Hawkins kinetic parameters (Ki, K1, extraction fraction) were assessed using 50- or 75-minutes of scan data as well as for scan durations that were retrospectively shortened. The error of the kinetic uptake parameters was calculated in bone regions throughout the knee.ResultsThe mean error of Patlak Ki, Hawkins Ki, K1, and extraction fraction was less than 10% for scan durations exceeding 30 min and decreased with increasing scan duration.ConclusionsThe length of dynamic data acquisition can be reduced to as short as 30 min while retaining accuracy within the limits of reproducibility of Hawkins kinetic uptake parameters

Advanced Magnetic Resonance Imaging and Molecular Imaging of the Painful Knee

Chronic knee pain is a common condition. Causes of knee pain include trauma, inflammation, and degeneration, but in many patients the pathophysiology remains unknown. Recent developments in advanced magnetic resonance imaging (MRI) techniques and molecular imaging facilitate more in-depth research focused on the pathophysiology of chronic musculoskeletal pain and more specifically inflammation. The forthcoming new insights can help develop better targeted treatment, and some imaging techniques may even serve as imaging biomarkers for predicting and assessing treatment response in the future. This review highlights the latest developments in perfusion MRI, diffusion MRI, and molecular imaging with positron emission tomography/MRI and their application in the painful knee. The primary focus is synovial inflammation, also known as synovitis. Bone perfusion and bone metabolism are also addressed.</p

In vivo Magnetic Resonance Imaging of Tumor Protease Activity

Increased expression of cathepsins has diagnostic as well as prognostic value in several types of cancer. Here, we demonstrate a novel magnetic resonance imaging (MRI) method, which uses poly-L-glutamate (PLG) as an MRI probe to map cathepsin expression in vivo, in a rat brain tumor model. This noninvasive, high-resolution and non-radioactive method exploits the differences in the CEST signals of PLG in the native form and cathepsin mediated cleaved form. The method was validated in phantoms with known physiological concentrations, in tumor cells and in an animal model of brain tumor along with immunohistochemical analysis. Potential applications in tumor diagnosis and evaluation of therapeutic response are outlined

Endogenous chemical exchange based magnetic resonance imaging methods and their applications

Molecular imaging has the potential for the diagnosis of disease at the earliest causative stages, development of disease biomarkers, characterization of the preclinical stages of metabolic or molecular disturbance, and real-time monitoring of disease progression as well as therapeutic response. While many methods have been proposed for molecular imaging in vivo, factors such as suboptimal spatial resolution and the use of invasive contrast agents have limited their application in clinical settings. Magnetic Resonance Imaging (MRI) is a non-invasive, non-ionizing, high resolution imaging technique, which is widely utilized clinically to provide exquisite anatomical images. Chemical exchange provides an opportunity to make MRI sensitive to information about the concentrations of endogenous metabolites and their environments. In this Dissertation, we developed and implemented techniques that exploit the amine proton exchange phenomenon to quantify endogenous metabolites in biological tissues, in vivo. Specifically, we developed a new method to measure proton exchange which combines chemical exchange saturation transfer (CEST) and T1ρ magnetization preparation methods (CESTrho) to detect metabolites with exchangeable protons in the slow to intermediate exchange regime with enhanced sensitivity. Furthermore, the magnetization scheme of this new method can be customized to make it insensitive to changes in exchange rate, and thereby to pH, while retaining linear dependence on metabolite proton concentration. Additionally, for the first time, the CEST effect from amine protons of glutamate (GluCEST) was characterized and exploited to image Glu with high spatial resolution in the brain and spinal cord at ultra-high field (≥7T). Finally, we characterized the CEST effect of creatine kinase reaction metabolites and developed and optimized methods for measuring the CEST effect from Cr (CrCEST). The feasibility of measuring changes in CrCEST in calf muscles following plantar flexion exercises was shown with high spatial resolution. These methods and applications demonstrate the potential of amine CEST MRI to non-invasively and quantitatively measure endogenous glutamate and creatine changes in vivo with high resolution, which can be exploited as biomarkers of diagnosis and treatment monitoring in a range of pathologies

Endogenous chemical exchange based magnetic resonance imaging methods and their applications

Molecular imaging has the potential for the diagnosis of disease at the earliest causative stages, development of disease biomarkers, characterization of the preclinical stages of metabolic or molecular disturbance, and real-time monitoring of disease progression as well as therapeutic response. While many methods have been proposed for molecular imaging in vivo, factors such as suboptimal spatial resolution and the use of invasive contrast agents have limited their application in clinical settings. Magnetic Resonance Imaging (MRI) is a non-invasive, non-ionizing, high resolution imaging technique, which is widely utilized clinically to provide exquisite anatomical images. Chemical exchange provides an opportunity to make MRI sensitive to information about the concentrations of endogenous metabolites and their environments. In this Dissertation, we developed and implemented techniques that exploit the amine proton exchange phenomenon to quantify endogenous metabolites in biological tissues, in vivo. Specifically, we developed a new method to measure proton exchange which combines chemical exchange saturation transfer (CEST) and T1ρ magnetization preparation methods (CESTrho) to detect metabolites with exchangeable protons in the slow to intermediate exchange regime with enhanced sensitivity. Furthermore, the magnetization scheme of this new method can be customized to make it insensitive to changes in exchange rate, and thereby to pH, while retaining linear dependence on metabolite proton concentration. Additionally, for the first time, the CEST effect from amine protons of glutamate (GluCEST) was characterized and exploited to image Glu with high spatial resolution in the brain and spinal cord at ultra-high field (≥7T). Finally, we characterized the CEST effect of creatine kinase reaction metabolites and developed and optimized methods for measuring the CEST effect from Cr (CrCEST). The feasibility of measuring changes in CrCEST in calf muscles following plantar flexion exercises was shown with high spatial resolution. These methods and applications demonstrate the potential of amine CEST MRI to non-invasively and quantitatively measure endogenous glutamate and creatine changes in vivo with high resolution, which can be exploited as biomarkers of diagnosis and treatment monitoring in a range of pathologies

Potential of PET-MRI for imaging of non-oncologic musculoskeletal disease

Early detection of musculoskeletal disease leads to improved therapies and patient outcomes, and would benefit greatly from imaging at the cellular and molecular level. As it becomes clear that assessment of multiple tissues and functional processes are often necessary to study the complex pathogenesis of musculoskeletal disorders, the role of multi-modality molecular imaging becomes increasingly important. New positron emission tomography-magnetic resonance imaging (PET-MRI) systems offer to combine high-resolution MRI with simultaneous molecular information from PET to study the multifaceted processes involved in numerous musculoskeletal disorders. In this article, we aim to outline the potential clinical utility of hybrid PET-MRI to these non-oncologic musculoskeletal diseases. We summarize current applications of PET molecular imaging in osteoarthritis (OA), rheumatoid arthritis (RA), metabolic bone diseases and neuropathic peripheral pain. Advanced MRI approaches that reveal biochemical and functional information offer complementary assessment in soft tissues. Additionally, we discuss technical considerations for hybrid PET-MR imaging including MR attenuation correction, workflow, radiation dose, and quantification

High resolution T1ρ mapping of in vivo human knee cartilage at 7T.

Spin lattice relaxation time in rotating frame (T1ρ) mapping of human knee cartilage has shown promise in detecting biochemical changes during osteoarthritis. Due to higher field strength, MRI at 7T has advantages in term of SNR compared to clinical MR scanners and this can be used to increase in image resolution. Objective of current study was to evaluate the feasibility of high resolution T1ρ mapping of in vivo human knee cartilage at 7T MR scanner.In this study we have used a T1ρ prepared GRE pulse sequence for obtaining high resolution (in plan resolution  = 0.2 mm2) T1ρ MRI of human knee cartilage at 7T. The effect of a global and localized reference frequency and reference voltage setting on B0, B1 and T1ρ maps in cartilage was evaluated. Test-retest reliability results of T1ρ values from asymptomatic subjects as well as T1ρ maps from abnormal cartilage of two human subjects are presented. These results are compared with T1ρ MRI data obtained from 3T.Our approach enabled acquisition of 3D-T1ρ data within allowed SAR limits at 7T. SNR of cartilage on T1ρ weighted images was greater than 90. Off-resonance effects present in the cartilage B0, B1 and T1ρ maps obtained using global shim and reference frequency and voltage setting, were reduced by the proposed localized reference frequency and voltage setting. T1ρ values of cartilage obtained with the localized approach were reproducible. Abnormal knee cartilage showed elevated T1ρ values in affected regions. T1ρ values at 7T were significantly lower (p<0.05) compared to those obtained at 3T.In summary, by using proposed localized frequency and voltage setting approach, high-resolution 3D-T1ρ maps of in vivo human knee cartilage can be obtained in clinically acceptable scan times (<30 min) and SAR constraints, which provides the ability to characterize cartilage molecular integrity

Datasheet2_Effects of dynamic [18F]NaF PET scan duration on kinetic uptake parameters in the knee.xlsx

IntroductionAccurately estimating bone perfusion and metabolism using [18F]NaF kinetics from shorter scan times could help address concerns related to patient comfort, motion, and throughput for PET scans. We examined the impact of changing the PET scan duration on the accuracy of [18F]NaF kinetic parameters in the knee.MethodsBoth knees of twenty participants with and without osteoarthritis were scanned using a hybrid PET-MRI system (53 ± 13 years, BMI 25.9 ± 4.2 kg/m2, 13 female). Seventeen participants were scanned for 54 ± 2 min, and an additional three participants were scanned for 75 min. Patlak Ki and Hawkins kinetic parameters (Ki, K1, extraction fraction) were assessed using 50- or 75-minutes of scan data as well as for scan durations that were retrospectively shortened. The error of the kinetic uptake parameters was calculated in bone regions throughout the knee.ResultsThe mean error of Patlak Ki, Hawkins Ki, K1, and extraction fraction was less than 10% for scan durations exceeding 30 min and decreased with increasing scan duration.ConclusionsThe length of dynamic data acquisition can be reduced to as short as 30 min while retaining accuracy within the limits of reproducibility of Hawkins kinetic uptake parameters.</p