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Purpose: The objective was to develop a fully automated algorithm that generates confidence maps to identify regions valid for analysis of quantitative proton density fat fraction (PDFF) and R2*$$ {R}_2^{\ast } $$ maps of the liver, generated with chemical shift–encoded MRI (CSE‐MRI). Confidence maps are urgently needed for automated quality assurance, particularly with the emergence of automated segmentation and analysis algorithms. Methods: Confidence maps for both PDFF and R2*$$ {R}_2^{\ast } $$ maps are generated based on goodness of fit, measured by normalized RMS error between measured complex signals and the CSE‐MRI signal model. Based on Cramér‐Rao lower bound and Monte‐Carlo simulations, normalized RMS error threshold criteria were developed to identify unreliable regions in quantitative maps. Simulation, phantom, and in vivo clinical studies were included. To analyze the clinical data, a board‐certified radiologist delineated regions of interest (ROIs) in each of the nine liver segments for PDFF and R2*$$ {R}_2^{\ast } $$ analysis in consecutive clinical CSE‐MRI data sets. The percent area of ROIs in areas deemed unreliable by confidence maps was calculated to assess the impact of confidence maps on real‐world clinical PDFF and R2*$$ {R}_2^{\ast } $$ measurements. Results: Simulations and phantom studies demonstrated that the proposed algorithm successfully excluded regions with unreliable PDFF and R2*$$ {R}_2^{\ast } $$ measurements. ROI analysis by the radiologist revealed that 2.6% and 15% of the ROIs were placed in unreliable areas of PDFF and R2*$$ {R}_2^{\ast } $$ maps, as identified by confidence maps. Conclusion: A proposed confidence map algorithm that identifies reliable areas of PDFF and R2*$$ {R}_2^{\ast } $$ measurements from CSE‐MRI acquisitions was successfully developed. It demonstrated technical and clinical feasibility. [ABSTRACT FROM AUTHOR]

Purpose: Ktrans$$ {K}^{\mathrm{trans}} $$ has often been proposed as a quantitative imaging biomarker for diagnosis, prognosis, and treatment response assessment for various tumors. None of the many software tools for Ktrans$$ {K}^{\mathrm{trans}} $$ quantification are standardized. The ISMRM Open Science Initiative for Perfusion Imaging–Dynamic Contrast‐Enhanced (OSIPI‐DCE) challenge was designed to benchmark methods to better help the efforts to standardize Ktrans$$ {K}^{\mathrm{trans}} $$ measurement. Methods: A framework was created to evaluate Ktrans$$ {K}^{\mathrm{trans}} $$ values produced by DCE‐MRI analysis pipelines to enable benchmarking. The perfusion MRI community was invited to apply their pipelines for Ktrans$$ {K}^{\mathrm{trans}} $$ quantification in glioblastoma from clinical and synthetic patients. Submissions were required to include the entrants' Ktrans$$ {K}^{\mathrm{trans}} $$ values, the applied software, and a standard operating procedure. These were evaluated using the proposed OSIPIgold$$ \mathrm{OSIP}{\mathrm{I}}_{\mathrm{gold}} $$ score defined with accuracy, repeatability, and reproducibility components. Results: Across the 10 received submissions, the OSIPIgold$$ \mathrm{OSIP}{\mathrm{I}}_{\mathrm{gold}} $$ score ranged from 28% to 78% with a 59% median. The accuracy, repeatability, and reproducibility scores ranged from 0.54 to 0.92, 0.64 to 0.86, and 0.65 to 1.00, respectively (0–1 = lowest–highest). Manual arterial input function selection markedly affected the reproducibility and showed greater variability in Ktrans$$ {K}^{\mathrm{trans}} $$ analysis than automated methods. Furthermore, provision of a detailed standard operating procedure was critical for higher reproducibility. Conclusions: This study reports results from the OSIPI‐DCE challenge and highlights the high inter‐software variability within Ktrans$$ {K}^{\mathrm{trans}} $$ estimation, providing a framework for ongoing benchmarking against the scores presented. Through this challenge, the participating teams were ranked based on the performance of their software tools in the particular setting of this challenge. In a real‐world clinical setting, many of these tools may perform differently with different benchmarking methodology. [ABSTRACT FROM AUTHOR]

This manuscript describes the ISMRM OSIPI (Open Science Initiative for Perfusion Imaging) lexicon for dynamic contrast‐enhanced and dynamic susceptibility‐contrast MRI. The lexicon was developed by Taskforce 4.2 of OSIPI to provide standardized definitions of commonly used quantities, models, and analysis processes with the aim of reducing reporting variability. The taskforce was established in February 2020 and consists of medical physicists, engineers, clinicians, data and computer scientists, and DICOM (Digital Imaging and Communications in Medicine) standard experts. Members of the taskforce collaborated via a slack channel and quarterly virtual meetings. Members participated by defining lexicon items and reporting formats that were reviewed by at least two other members of the taskforce. Version 1.0.0 of the lexicon was subject to open review from the wider perfusion imaging community between January and March 2022, and endorsed by the Perfusion Study Group of the ISMRM in the summer of 2022. The initial scope of the lexicon was set by the taskforce and defined such that it contained a basic set of quantities, processes, and models to enable users to report an end‐to‐end analysis pipeline including kinetic model fitting. We also provide guidance on how to easily incorporate lexicon items and definitions into free‐text descriptions (e.g., in manuscripts and other documentation) and introduce an XML‐based pipeline encoding format to encode analyses using lexicon definitions in standardized and extensible machine‐readable code. The lexicon is designed to be open‐source and extendable, enabling ongoing expansion of its content. We hope that widespread adoption of lexicon terminology and reporting formats described herein will increase reproducibility within the field. [ABSTRACT FROM AUTHOR]

Chronic musculoskeletal pain is among the most highly prevalent diseases worldwide. Managing patients with chronic pain remains very challenging because current imaging techniques focus on morphological causes of pain that can be inaccurate and misleading. Moving away from anatomical constructs of disease, molecular imaging has emerged as a method to identify diseases according to their molecular, physiologic, or cellular signatures that can be applied to the variety of biomolecular changes that occur in nociception and pain processing and therefore have tremendous potential for precisely pinpointing the source of a patient's pain. Several molecular imaging approaches to image the painful process are now available, including imaging of voltage-gated sodium channels, calcium channels, hypermetabolic processes, the substance P receptor, the sigma-1 receptor, and imaging of macrophage trafficking. This article provides an overview of promising molecular imaging approaches for the imaging of musculoskeletal pain with a focus on preclinical methods. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is among the top 10 burdensome diseases, with the knee the most affected joint. Magnetic resonance imaging (MRI) allows whole-knee assessment, making it ideally suited for imaging OA, considered a multitissue disease. Three-dimensional (3D) MRI enables the comprehensive assessment of OA, including quantitative morphometry of various joint tissues. Manual tissue segmentation on 3D MRI is challenging but may be overcome by advanced automated image analysis methods including artificial intelligence (AI). This review presents examples of the utility of 3D MRI for knee OA, focusing on the articular cartilage, bone, meniscus, synovium, and infrapatellar fat pad, and it highlights several applications of AI that facilitate segmentation, lesion detection, and disease classification. [ABSTRACT FROM AUTHOR]

BACKGROUND: Structural abnormalities associated with osteoarthritis (OA) are found in some patients with patellofemoral pain (PFP). OBJECTIVES: To investigate the association between early signs of OA on magnetic resonance imaging (MRI) and characteristics from self-reported measures and physical examination in patients with PFP METHODS: This exploratory study included data from patients with PFP from a previously published cross-sectional case-control study (n = 64; 55% female; mean ± SD age, 23.4 ± 7.0 years). Structural OA features (osteophytes, bone marrow lesions, cartilage defects, Hoffa synovitis, patellar tendon abnormalities) and quantitative T2 measurements of cartilage composition were extracted from MRI. Associations between characteristics from self-reported measures (pain at rest, pain during stair walking, knee function, duration of complaints, hours of sports participation each week), physical examination (crepitus, quadriceps strength), and early MRI signs of OA were assessed. RESULTS: Symptom duration was associated with bone marrow lesions in the patella (odds ratio [OR] = 1.1; 95% confidence Interval [Cl]: 1,0,1.2). Sports participation (hours per week) was inversely associated with patellar tendon abnormalities on MRI (OR = 0.8; 95% Cl: 0.6,1.0). Crepitus and bilateral nature of the complaints were associated with minor patellar cartilage defects (OR = 12.0; 95% Cl: 2.3,63.6 and OR = 7.6; 95% Cl: 1.1,53.8, respectively). There were no significant associations between clinical characteristics and cartilage T2 relaxation time. CONCLUSION: Presence of crepitus, bilateral complaints, a long PFP symptom duration, and reduced weekly sport participation were associated with early signs of OA in a young PFP population. LEVEL OF EVIDENCE: Etiology, level 2c. [ABSTRACT FROM AUTHOR]

Background: Patellofemoral malalignment has been observed among people with patellofemoral pain (PFP) and may be associated with the presence of imaging features of osteoarthritis, symptoms, and function. Purpose: To determine whether patellofemoral joint alignment and bony shape are associated with (1) cartilage, bone, and soft tissue morphological abnormalities defined on magnetic resonance imaging (MRI) and (2) reported symptoms and function among people with PFP. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Participants (mean 6 SD age, 30.2 6 9.5 years; range, 14-50 years; 78 females, 58.6%) completed questionnaires regarding demographics, pain, symptoms, and function and underwent a 3-T MRI scan of their more symptomatic eligible knee. Structural MRI abnormalities were scored with the MOAKS (Magnetic Resonance Imaging Osteoarthritis Knee Score), and MRI alignment and shape were measured with standardized methods. Associations among MOAKS features, PFP symptoms, and alignment and shape measures were evaluated with regression analyses (a = .05). Results: Minor cartilage defects were present in 22 (16.5%) participants, patellar osteophytes in 83 (62.4%), anterior femur osteophytes in 29 (21.8%), Hoffa synovitis in 81 (60.9%), and prefemoral fat pad synovitis in 49 (36.8%). A larger Insall-Salvati ratio was significantly associated with the presence of patellar osteophytes (odds ratio [OR], 51.82; 95% CI, 4.20-640.01), Hoffa synovitis (OR, 60.37; 95% CI, 4.66-782.61), and prefemoral fat pad synovitis (OR, 43.31; 95% CI, 4.28-438.72) in the patellofemoral joint. A larger patellar tilt angle was significantly associated with the presence of minor cartilage defects (OR, 1.10; 95% CI, 1.00- 1.20), the presence of patellar osteophytes (OR 1.12; 95%CI 1.02-1.22), and prefemoral fat pad synovitis (OR, 1.11; 95% CI, 1.03- 1.20) in the patellofemoral joint. Finally, a larger bisect offset was significantly associated with the presence of minor cartilage defects (OR, 1.05; 95% CI, 1.00-1.11) and patellar osteophytes (OR, 1.07; 95% CI, 1.01-1.14) in the patellofemoral joint. The majority of patellofemoral alignment measures were not associated with symptoms or function. Conclusion: For people with PFP, the presence of morphological abnormalities defined on MRI appears to be related to particular patellofemoral alignment measures, including higher Insall-Salvati ratio (indicating patella alta), larger patellar tilt angle (indicating greater lateral tilt), and larger bisect offset (indicating greater lateral displacement). Hardly any associations were found with symptoms or function. So there might be a distinct subgroup of PFP that is more prone to developing patellofemoral osteoarthritis later in life, as particular alignment measures seem to be associated with the presence of patellar osteophytes. Prospective studies are required to investigate the longitudinal relationship between alignment or bony shape and morphological abnormalities defined on MRI in this patient population. [ABSTRACT FROM AUTHOR]

Background: Altered perfusion might play an important role in the pathophysiology of patellofemoral pain (PFP), a common knee complaint with unclear pathophysiology.Purpose: To investigate differences in dynamic contrast-enhanced (DCE)-MRI perfusion parameters between patients with PFP and healthy control subjects.Population/subjects/phantom/specimen/animal Model: Thirty-five adult patients with PFP and 44 healthy adult control subjects.Field Strength/sequence: 3T DCE-MRI consisting of a sagittal, anterior-posterior, frequency-encoded, fat-suppressed 3D spoiled gradient-echo sequence with intravenous contrast administration.Assessment: Patellar bone volumes of interest (VOIs) were delineated by a blinded observer. Quantitative perfusion parameters (kep and ktrans ) were calculated from motion-compensated DCE-MRI data by fitting Tofts' model. Weighted mean and unweighted median values of kep and ktrans were computed within the patellar bone VOIs.Statistical Tests: Differences in patellar bone perfusion parameters were compared between groups by linear regression analyses, adjusted for confounders.Results: Mean differences of weighted mean and unweighted median were 0.0039 (95% confidence interval [CI] -0.0013; 0.0091) and 0.0052 (95% CI -0.0078; 0.018) for ktrans , and 0.046 (95% CI -0.021; 0.11) and 0.069 (95% CI -0.017; 0.15) for kep , respectively. All perfusion parameters were not significantly different between groups (P-values: 0.32; 0.47 for ktrans , and 0.24; 0.15) for kep . However, a significant difference in variance between populations was observed for ktrans (P-value 0.007).Data Conclusion: Higher patellar bone perfusion parameters were found in patients with PFP when compared to healthy control subjects, but these differences were not statistically significant. This result, and the observed significant difference in ktrans variance, warrant further research.Level Of Evidence: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1344-1350. [ABSTRACT FROM AUTHOR]

Background: Structural abnormalities of the patellofemoral joint might play a role in the pathogenesis of patellofemoral pain (PFP), a common knee problem among young and physically active individuals. No previous study has investigated if PFP is associated with structural abnormalities of the patellofemoral joint using high-resolution magnetic resonance imaging (MRI). Purpose: To investigate the presence of structural abnormalities of the patellofemoral joint on high-resolution MRI in patients with PFP compared with healthy control subjects. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients with PFP and healthy control subjects between 14 and 40 years of age underwent high-resolution 3-T MRI. All images were scored using the Magnetic Resonance Imaging Osteoarthritis Knee Score with the addition of specific patellofemoral features. Associations between PFP and the presence of structural abnormalities were analyzed using logistic regression analyses adjusted for age, body mass index (BMI), sex, and sports participation. Results: A total of 64 patients and 70 control subjects were included in the study. Mean ± SD age was 23.2 ± 6.4 years, mean BMI ± SD was 22.9 ± 3.4 kg/m2, and 56.7% were female. Full-thickness cartilage loss was not present. Minor patellar cartilage defects, patellar bone marrow lesions, and high signal intensity of the Hoffa fat pad were frequently seen in both patients (23%, 53%, and 58%, respectively) and control subjects (21%, 51%, and 51%, respectively). After adjustment for age, BMI, sex, and sports participation, none of the structural abnormalities were statistically significantly associated with PFP. Conclusion: Structural abnormalities of the patellofemoral joint have been hypothesized as a factor in the pathogenesis of PFP, but the study findings suggest that structural abnormalities of the patellofemoral joint on MRI are not associated with PFP. [ABSTRACT FROM AUTHOR]

Purpose: Cardiac-induced liver motion can bias liver ADC measurements and compromise reproducibility. The purpose of this work was to enable motion-robust DWI on multiple MR scanners and assess reproducibility of the resulting liver ADC measurements., Methods: First moment-optimized diffusion imaging (MODI) was implemented on three MR scanners with various gradient performances and field strengths. MODI-DWI and conventional Stejskal-Tanner monopolar (MONO) DWI were acquired in eight (N = 8) healthy volunteers on each scanner, and DWI repetitions were combined using three different averaging methods. For each combination of scanner, acquisition, and averaging method, ADC measurements from each liver segment were collected. Systematic differences in ADC values between scanners and methods were assessed with linear mixed effects modeling, and reproducibility was quantified via reproducibility coefficients., Results: MODI reduced left-right liver lobe ADC bias from 0.43 × 10 -3  mm 2 /s (MONO) to 0.19 × 10 -3  mm 2 /s (MODI) when simple (unweighted) repetition averaging was used. The bias was reduced from 0.23 × 10 -3  mm 2 /s to 0.06 × 10 -3  mm 2 /s using weighted averaging, and 0.14 × 10 -3  mm 2 /s to 0.01 × 10 -3  mm 2 /s using squared weighted averaging. There was no significant difference in ADC measurements between field strengths or scanner gradient performance. MODI improved reproducibility coefficients compared to MONO: 0.84 × 10 -3  mm 2 /s vs. 0.63 × 10 -3  mm 2 /s (MODI vs. MONO) for simple averaging, 0.66 × 10 -3  mm 2 /s vs. 0.50 × 10 -3  mm 2 /s for weighted averaging, and 0.61 × 10 -3  mm 2 /s vs. 0.47 × 10 -3  mm 2 /s for squared weighted averaging., Conclusion: The feasibility of motion-robust liver DWI using MODI was demonstrated on multiple MR scanners. MODI improved interlobar agreement and reproducibility of ADC measurements in a healthy cohort., (© 2024 The Author(s). Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Objectives: Ferumoxytol is a superparamagnetic iron-oxide product that is increasingly used off-label for contrast-enhanced magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). With the recent regulatory approval of generic ferumoxytol, there may be an opportunity to reduce cost, so long as generic ferumoxytol has similar imaging performance to brand name ferumoxytol. This study aims to compare the relaxation-concentration dependence and MRI performance of brand name ferumoxytol with generic ferumoxytol through phantom and in vivo experiments. The secondary purpose was to determine the optimal flip angle and optimal weight-based dosing., Materials and Methods: Phantom experiments were performed using both brand name (AMAG Pharmaceuticals) and generic (Sandoz Pharmaceuticals) ferumoxytol products. Each ferumoxytol product was diluted in saline, and separately in adult bovine whole blood, at 5 iron concentrations ranging from 0.3 to 2.1 mM. Vials were placed in an MR-compatible water bath at 37°C and imaged at both 1.5 T and 3.0 T. Longitudinal and transverse relaxation rate constants (R1, R2, R2*) were measured for each ferumoxytol concentration, and relaxation-concentration curves were estimated. An in vivo dose accumulation study with flip angle optimization was also implemented using a cross-over design, in healthy volunteers. Cumulative doses of 1, 3, 5, and 7 mg/kg diluted ferumoxytol were administered prior to MRA of the chest on a 3.0 T clinical MRI system. For each incremental dose, the flip angle was varied from 40° to 10° in -10° increments over 5 breath-holds followed by a repeated 40° flip angle acquisition. Regions of interest were drawn in the aortic arch, paraspinous muscles, and a noisy area outside of the patient, free from obvious artifact. Signal-to-noise ratio (SNR) was calculated as the quotient of the average signal in the aortic arch and the standard deviation of the noise, corrected for a Rician noise distribution. Contrast-to-noise ratio was calculated as the difference in SNR between the aorta and paraspinous muscles. Absolute SNR and contrast-to-noise ratio values were compared between products for different flip angles and doses., Results: There were no statistically significant or clinically relevant differences in relaxation-concentration curves between AMAG and Sandoz products in phantom experiments. Six healthy volunteers (38.8 ± 11.5 years, 3 female, 3 male) were successfully recruited and completed both imaging visits. No clinically relevant differences in image quality were observed between ferumoxytol products. The optimal flip angle range and dose for both products was 20°-30° and 5 mg/kg, respectively., Conclusions: Brand name and generic ferumoxytol products can be used interchangeably for MRA., Competing Interests: Conflicts of interest and sources of funding: No author has any relevant conflicts. Unrelated to this work, Dr Reeder has ownership interests in Calimetrix, Reveal Pharmaceuticals, Cellectar Biosciences, Elucent Medical, Vista.AI, and RevOps. Dr Reeder provides consulting services to Bracco Diagnostics, ProTara, Bayer Healthcare, and Marea Therapeutics. Further, the University of Wisconsin receives research support from GE Healthcare, Bracco Diagnostics, Bayer Healthcare, and Pfizer. This project was supported by the Departments of Radiology and Medical Physics, University of Wisconsin., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To determine the efficacy of genicular artery embolisation (GAE) compared with sham GAE for pain reduction in patients with symptomatic mild-to-moderate knee osteoarthritis (KOA)., Design: Double-blind randomised sham-controlled clinical trial conducted from June 2019 to December 2021. The follow-up period was 4 months., Setting: Single-centre study conducted at a university medical centre in Rotterdam, Netherlands., Participants: 58 adults with symptomatic mild-to-moderate KOA not improving with conservative treatment., Interventions: Participants were randomised to receive either GAE treatment or a sham GAE treatment., Main Outcome Measures: The primary outcome was reduction of pain measured with the Knee Injury and Osteoarthritis Outcome Score pain subscale (0-100, with 0 representing the worst pain outcome and 100 the best) after 4 months. Outcomes were assessed at baseline and 1 and 4 months., Results: From June 2019 to December 2021, 58 patients were included. 29 patients were randomised to the GAE group and 29 to the sham group. All participants completed the study. The mean pain reduction after 4 months was 21.4 (95% CI 13.9 to 28.8) for the GAE group and 18.4 points (95% CI 11.6 to 25.1) for the sham group. The between-group difference for the mean pain reduction was 3.0 (95% CI -7.1 to 13.0) with an estimated Cohen's d effect size of d = 0.15 (95% CI -0.37 to 0.66). Group allocation was not a significant contributor to pain reduction (p = 0.31). No serious adverse events (AEs) occurred. 23 mild AEs occurred in the GAE group and 5 in the sham group., Conclusion: We did not establish a clinical effect of GAE in patients with mild-to-moderate KOA as GAE produced a similar effect on pain reduction as a sham GAE procedure., Trial Registration Number: NCT03884049., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Patellofemoral pain (PFP) is a common knee condition and possible precursor of knee osteoarthritis (OA). Inflammation, leading to an increased perfusion, or increased volume of the infrapatellar fat pad (IPFP) may induce knee pain. The aim of the study was to compare quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters, as imaging biomarkers of inflammation, and volume of the IPFP between patients with PFP and controls and between patients with and without IPFP edema or joint effusion., Methods: Patients with PFP and healthy controls were included and underwent non-fat suppressed 3D fast-spoiled gradient-echo (FSPGR) and DCE-MRI. Image registration was applied to correct for motion. The IPFP was delineated on FSPGR using Horos software. Volume was calculated and quantitative perfusion parameters were extracted by fitting extended Tofts' pharmacokinetic model. Differences in volume and DCE-MRI parameters between patients and controls were tested by linear regression analyses. IPFP edema and effusion were analyzed identically., Results: Forty-three controls and 35 PFP patients were included. Mean IPFP volume was 26.04 (4.18) mL in control subjects and 27.52 (5.37) mL in patients. Median K trans was 0.017 (0.016) min -1 in control subjects and 0.016 (0.020) min -1 in patients. None of the differences in volume and perfusion parameters were statistically significant. Knees with effusion showed a higher perfusion of the IPFP compared to knees without effusion in patients only., Conclusions: The IPFP has been implicated as source of knee pain, but higher DCE-MR blood perfusion, an imaging biomarker of inflammation, and larger volume are not associated with PFP. Patient's knees with effusion showed a higher perfusion, pointing towards inflammation., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/qims-20-441). EHGO serves as an unpaid Associate Editor of Quantitative Imaging in Medicine and Surgery. Dr. RA van der Heijden reports grants from European Society Skeletal Radiology, during the conduct of the study; Dr. M van Middelkoop reports grants from Erasmus University Rotterdam, during the conduct of the study; Dr. SMABZ reports grants from Dutch Artritis Foundation, during the conduct of the study; Dr. EHGO reports grants from RSNA, during the conduct of the study. The other authors have no conflicts of interest to declare., (2021 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

Background: Patellofemoral pain (PFP) patients show increased prevalence of patellar malalignment. Structural and alignment abnormalities of the patellofemoral joint (PFJ) may play a role in development of PFP and patellofemoral osteoarthritis (PFOA)., Objectives: Evaluating associations of patellofemoral alignment and femoral geometry with bony and cartilaginous abnormalities in PFP patients and healthy control subjects., Methods: Data from a case-control study were used (64 PFP subjects, 70 control subjects, 57% female, age 23.2 (6.4)). Alignment and femoral geometry measures in the PFJ were determined using MRI. Structural abnormalities in the PFJ associated with OA (bone marrow lesions, osteophytes, minor cartilage defects and Hoffa-synovitis), quantified cartilage composition (T1ρ relaxation times) in the PFJ and perfusion within the patellar bone were examined using different MRI techniques. Associations were analyzed using regression analyses, adjusted for potential confounders., Results: Lateral patellar tilt was negatively associated with presence of osteophytes on both patella (OR 0.91; 95% CI 0.84 to 0.98), anterior femur (OR 0.92; 95% CI 0.84 to 0.99) and minor cartilage defects on patella (OR 0.91; 95% CI 0.84 to 0.99). Patella alta was positively associated with the presence of bone marrow lesions in the patella and minor cartilage defects (OR 48.33; 95% CI 4.27 to 547.30 and OR 17.51; 95% CI 1.17 to 262.57, respectively). Patella alta and medial patellar translation were positively associated with T1ρ relaxation times within trochlear cartilage (β 5.2; 95% CI 0.77 to 9.58, and 0.36; 95% CI 0.08 to 0.64, respectively). None of the alignment and geometry measures were associated with bone perfusion., Conclusion: Our study implies that associations between patellofemoral alignment and geometry and structural joint abnormalities linked to OA are already present in both PFP patients and healthy control subjects., (© 2020 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Study Design Retrospective cohort. Background Although persons with patellofemoral pain (PFP) often report pain with prolonged sitting, little is known about the prevalence and characteristics of sitting pain. Objectives To describe the proportion of persons with PFP who experience problems with prolonged sitting and to determine patient characteristics associated with sitting pain. Methods Four hundred fifty-eight participants with a diagnosis of PFP from 4 separate studies were included. Item 8 of the Anterior Knee Pain Scale was used to define the presence of problems with prolonged sitting with knee flexion, based on 3 categories: (1) "no difficulty," (2) "pain after exercise," or (3) "problems with prolonged sitting." Differences in demographic and clinical variables between categories were evaluated using Kruskal-Wallis tests (P<.05). Results Two hundred forty-nine (54.4% of the study sample) participants reported problems with prolonged sitting, and 121 (26.4%) reported sitting pain after exercise. Compared to those with no difficulty sitting (n = 88), participants classified as having problems with prolonged sitting were significantly younger (P = .038), more likely to be female (P = .033), had a lower body mass index (P = .027), reported higher pain severity (P<.001) and lower Anterior Knee Pain Scale scores (P<.001), and more frequently reported problems with squatting (P<.001). Conclusion Problems with prolonged sitting are evident in more than half of persons with PFP. Findings highlight the need to identify and adequately manage PFP associated with prolonged sitting. Further research should explore mechanisms of sitting pain and evaluate targeted interventions to reduce PFP with prolonged sitting. Level of Evidence Symptom prevalence study, level 2b. J Orthop Sports Phys Ther 2016;46(8):658-663. Epub 3 Jul 2016. doi:10.2519/jospt.2016.6470.

Background: Patellofemoral pain syndrome (PFPS) is a common knee problem characterised by retropatellar or peripatellar pain, which particularly affects adolescents and young adults. Exercise therapy is often prescribed., Aim: To assess the effects of exercise therapy in people with PFPS., Design: Systematic review., Setting: All settings., Population: Adolescents and adults with PFPS., Methods: A search was performed in nine databases up to May 2014, including the Cochrane Register, MEDLINE and EMBASE. Randomised and quasi-randomised trials evaluating the effect of exercise therapy in adolescents and adults with PFPS were considered for inclusion. Two review authors independently selected trials, extracted data and assessed risk of bias., Results: In total, 31 trials including 1690 participants were included in this review, of which most were at high risk of performance bias and detection bias due to lack of blinding. The included studies provided evidence for: exercise therapy versus control; exercise therapy versus other conservative interventions (e.g. taping); and different exercises or exercise programmes. Pooled data favoured exercise therapy over control for pain during activity (short term MD -1.46 [-2.39, -0.54]), usual pain (short term estimated MD -1.44 [-2.48,-0.39]), functional ability; (short term estimated MD 12.21 [6.44, 18.09] and long term recovery (RR 1.35 [0.99, 1.84]). Pooled data favoured hip and knee exercise over knee exercises alone for pain during activity (short-term MD -2.20 [3.80, -0.60]) and usual pain (short term MD-1.77 [-2.78,-0.76])., Conclusion: This review found very low quality but consistent evidence that exercise therapy for PFPS may result in clinically important reduction in pain and improvement in functional ability, as well as enhancing long-term recovery. There is some very low quality evidence that hip plus knee exercises may be more effective in reducing pain than knee exercise alone., Clinical Rehabilitation Impact: Very low quality evidence but consistent evidence indicates that exercise therapy benefits patients with PFP. However, there is insufficient evidence to determine the best form of exercise therapy and it is unknown whether this result would apply to all people with PFPS.

Background: Patellofemoral pain syndrome (PFPS) is a common knee problem, which particularly affects adolescents and young adults. PFPS, which is characterised by retropatellar (behind the kneecap) or peripatellar (around the kneecap) pain, is often referred to as anterior knee pain. The pain mostly occurs when load is put on the knee extensor mechanism when climbing stairs, squatting, running, cycling or sitting with flexed knees. Exercise therapy is often prescribed for this condition., Objectives: To assess the effects (benefits and harms) of exercise therapy aimed at reducing knee pain and improving knee function for people with patellofemoral pain syndrome., Search Methods: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (May 2014), the Cochrane Central Register of Controlled Trials (2014, Issue 4), MEDLINE (1946 to May 2014), EMBASE (1980 to 2014 Week 20), PEDro (to June 2014), CINAHL (1982 to May 2014) and AMED (1985 to May 2014), trial registers (to June 2014) and conference abstracts., Selection Criteria: Randomised and quasi-randomised trials evaluating the effect of exercise therapy on pain, function and recovery in adolescents and adults with patellofemoral pain syndrome. We included comparisons of exercise therapy versus control (e.g. no treatment) or versus another non-surgical therapy; or of different exercises or exercise programmes., Data Collection and Analysis: Two review authors independently selected trials based on pre-defined inclusion criteria, extracted data and assessed risk of bias. Where appropriate, we pooled data using either fixed-effect or random-effects methods. We selected the following seven outcomes for summarising the available evidence: pain during activity (short-term: ≤ 3 months); usual pain (short-term); pain during activity (long-term: > 3 months); usual pain (long-term); functional ability (short-term); functional ability (long-term); and recovery (long-term)., Main Results: In total, 31 heterogeneous trials including 1690 participants with patellofemoral pain are included in this review. There was considerable between-study variation in patient characteristics (e.g. activity level) and diagnostic criteria for study inclusion (e.g. minimum duration of symptoms) and exercise therapy. Eight trials, six of which were quasi-randomised, were at high risk of selection bias. We assessed most trials as being at high risk of performance bias and detection bias, which resulted from lack of blinding.The included studies, some of which contributed to more than one comparison, provided evidence for the following comparisons: exercise therapy versus control (10 trials); exercise therapy versus other conservative interventions (e.g. taping; eight trials evaluating different interventions); and different exercises or exercise programmes. The latter group comprised: supervised versus home exercises (two trials); closed kinetic chain (KC) versus open KC exercises (four trials); variants of closed KC exercises (two trials making different comparisons); other comparisons of other types of KC or miscellaneous exercises (five trials evaluating different interventions); hip and knee versus knee exercises (seven trials); hip versus knee exercises (two studies); and high- versus low-intensity exercises (one study). There were no trials testing exercise medium (land versus water) or duration of exercises. Where available, the evidence for each of seven main outcomes for all comparisons was of very low quality, generally due to serious flaws in design and small numbers of participants. This means that we are very unsure about the estimates. The evidence for the two largest comparisons is summarised here. Exercise versus control. Pooled data from five studies (375 participants) for pain during activity (short-term) favoured exercise therapy: mean difference (MD) -1.46, 95% confidence interval (CI) -2.39 to -0.54. The CI included the minimal clinically important difference (MCID) of 1.3 (scale 0 to 10), indicating the possibility of a clinically important reduction in pain. The same finding applied for usual pain (short-term; two studies, 41 participants), pain during activity (long-term; two studies, 180 participants) and usual pain (long-term; one study, 94 participants). Pooled data from seven studies (483 participants) for functional ability (short-term) also favoured exercise therapy; standardised mean difference (SMD) 1.10, 95% CI 0.58 to 1.63. Re-expressed in terms of the Anterior Knee Pain Score (AKPS; 0 to 100), this result (estimated MD 12.21 higher, 95% CI 6.44 to 18.09 higher) included the MCID of 10.0, indicating the possibility of a clinically important improvement in function. The same finding applied for functional ability (long-term; three studies, 274 participants). Pooled data (two studies, 166 participants) indicated that, based on the 'recovery' of 250 per 1000 in the control group, 88 more (95% CI 2 fewer to 210 more) participants per 1000 recovered in the long term (12 months) as a result of exercise therapy. Hip plus knee versus knee exercises. Pooled data from three studies (104 participants) for pain during activity (short-term) favoured hip and knee exercise: MD -2.20, 95% CI -3.80 to -0.60; the CI included a clinically important effect. The same applied for usual pain (short-term; two studies, 46 participants). One study (49 participants) found a clinically important reduction in pain during activity (long-term) for hip and knee exercise. Although tending to favour hip and knee exercises, the evidence for functional ability (short-term; four studies, 174 participants; and long-term; two studies, 78 participants) and recovery (one study, 29 participants) did not show that either approach was superior., Authors' Conclusions: This review has found very low quality but consistent evidence that exercise therapy for PFPS may result in clinically important reduction in pain and improvement in functional ability, as well as enhancing long-term recovery. However, there is insufficient evidence to determine the best form of exercise therapy and it is unknown whether this result would apply to all people with PFPS. There is some very low quality evidence that hip plus knee exercises may be more effective in reducing pain than knee exercise alone.Further randomised trials are warranted but in order to optimise research effort and engender the large multicentre randomised trials that are required to inform practice, these should be preceded by research that aims to identify priority questions and attain agreement and, where practical, standardisation regarding diagnostic criteria and measurement of outcome.