Advanced magnetic resonance imaging of cartilage components in haemophilic joints reveals that cartilage hemosiderin correlates with joint deterioration

Blood-Induced Arthropathy: A Major Disabling Complication of Haemophilia

Haemophilic arthropathy (HA) is one of the most serious complications of haemophilia. It starts with joint bleeding, leading to synovitis which, in turn, can cause damage to the cartilage and subchondral bone, eventually inducing degenerative joint disease. Despite significant improvements in haemophilia treatment over the past two decades and recent guidelines from ISTH and WFH recommending FVIII trough levels of at least 3 IU/dL during prophylaxis, patients with haemophilia still develop joint disease. The pathophysiology of HA is complex, involving both inflammatory and degenerative components. Early diagnosis is key for proper management. Imaging can detect joint subclinical changes and influence prophylaxis. Magnetic resonance imagining (MRI) and ultrasound are the most frequently used methods in comprehensive haemophilia care centres. Biomarkers of joint health have been proposed to determine osteochondral joint deterioration, but none of these biomarkers has been validated or used in clinical practice. Early prophylaxis is key in all severe haemophilia patients to prevent arthropathy. Treatment is essentially based on prophylaxis intensification and chronic joint pain management. However, there remain significant gaps in the knowledge of the mechanisms responsible for HA and prognosis-influencing factors. Better understanding in this area could produce more effective interventions likely to ultimately prevent or attenuate the development of HA.

Arthroscopic Excision of Pigmented Villonodular Synovitis of the Trochanteric Bursa

Trochanteric bursitis is a common disorder affecting middle-aged adults and usually presents with lateral-based hip pain and swelling. It usually responds to conservative measures, including adductor stretching, abductor strengthening, and select injections of corticosteroid or platelet-rich plasma. For refractory cases, excision, open or arthroscopic, is usually recommended. We observed a 55-year-old woman who had lateral hip pain and longstanding swelling consistent with refractory trochanteric bursitis. Her persistent symptoms, coupled with atypical findings on imaging, prompted an arthroscopic evaluation. Arthroscopic examination of the peritrochanteric space revealed a fulminant bursal inflammation that pierced through the iliotibial band. The bursal inflammation was excised arthroscopically and biopsy of the tissue revealed a diagnosis of pigmented villonodular synovitis (PVNS). The patient had an uneventful recovery and had a full resolution of symptoms with no recurrence noted at 3-year follow-up. This is the first reported case of arthroscopic excision of PVNS of the trochanteric bursa. Given that it may mimic trochanteric bursitis, it is important for clinicians to be aware of the possibility of this progressive condition for appropriate clinical intervention. [Orthopedics. 2023;46(6):e381-e383.].

Maladaptive lymphangiogenesis is associated with synovial iron accumulation and delayed clearance in factor VIII-deficient mice after induced hemarthrosis

BACKGROUND

Mechanisms of iron clearance from hemophilic joints are unknown.

OBJECTIVES

To better understand mechanisms of iron clearance following joint bleeding in a mouse model of hemophilia.

METHODS

Hemarthrosis was induced by subpatellar puncture in factor VIII (FVIII)-deficient (FVII-/-) mice, +/- periprocedural recombinant human FVIII, and hypocoagulable (HypoBALB/c) mice. HypoBALB/c mice experienced transient FVIII deficiency (anti-FVIII antibody) at the time of injury combined with warfarin-induced hypocoagulability. Synovial tissue was harvested weekly up to 6 weeks after injury for histological analysis, ferric iron and macrophage accumulation (CD68), blood and lymphatic vessel remodeling (αSMA; LYVE1). Synovial RNA sequencing was performed for FVIII-/- mice at days 0, 3, and 14 after injury to quantify expression changes of iron regulators and lymphatic markers.

RESULTS

Bleed volumes were similar in FVIII-/- and HypoBALB/c mice. However, pronounced and prolonged synovial iron accumulation colocalizing with macrophages and impaired lymphangiogenesis were detected only in FVIII-/- mice and were prevented by periprocedural FVIII. Gene expression changes involved in iron handling (some genes with dual roles in inflammation) and lymphatic markers supported proinflammatory milieu with iron retention and disturbed lymphangiogenesis.

CONCLUSION

Accumulation and delayed clearance of iron-laden macrophages were associated with defective lymphangiogenesis after hemarthrosis in FVIII-/- mice. The absence of such findings in HypoBALB/c mice suggests that intact lymphatics are required for removal of iron-laden macrophages and that these processes depend on FVIII availability. Studies to elucidate the biological mechanisms of disturbed lymphangiogenesis in hemophilia appear critical to develop new therapeutic targets.

Ultrashort echo time magnetization transfer imaging of knee cartilage and meniscus after long-distance running

OBJECTIVE

To assess the detection of changes in knee cartilage and meniscus of amateur marathon runners before and after long-distance running using a 3D ultrashort echo time MRI sequence with magnetization transfer preparation (UTE-MT).

METHODS

We recruited 23 amateur marathon runners (46 knees) in this prospective cohort study. MRI scans using UTE-MT and UTE-T2* sequences were performed pre-race, 2 days post-race, and 4 weeks post-race. UTE-MT ratio (UTE-MTR) and UTE-T2* were measured for knee cartilage (eight subregions) and meniscus (four subregions). The sequence reproducibility and inter-rater reliability were also investigated.

RESULTS

Both the UTE-MTR and UTE-T2* measurements showed good reproducibility and inter-rater reliability. For most subregions of cartilage and meniscus, the UTE-MTR values decreased 2 days post-race and increased after 4 weeks of rest. Conversely, the UTE-T2* values increased 2 days post-race and decreased after 4 weeks. The UTE-MTR values in lateral tibial plateau, central medial femoral condyle, and medial tibial plateau showed a significant decrease at 2 days post-race compared to the other two time points (p < 0.05). By comparison, no significant UTE-T2* changes were found for any cartilage subregions. For meniscus, the UTE-MTR values in medial posterior horn and lateral posterior horn regions at 2 days post-race were significantly lower than those at pre-race and 4 weeks post-race (p < 0.05). By comparison, only the UTE-T2* values in medial posterior horn showed a significant difference.

CONCLUSIONS

UTE-MTR is a promising method for the detection of dynamic changes in knee cartilage and meniscus after long-distance running.

KEY POINTS

• Long-distance running causes changes in the knee cartilage and meniscus. • UTE-MT monitors dynamic changes of knee cartilage and meniscal non-invasively. • UTE-MT is superior to UTE-T2* in monitoring dynamic changes in knee cartilage and meniscus.

How to assess, detect, and manage joint involvement in the era of transformational therapies: Role of point-of-care ultrasound

BACKGROUND

Patients with haemophilia experience recurring hemarthroses, mainly involving knees, elbows and ankles, which lead to haemophilic arthropathy, the major chronic complication of haemophilia. With new approaches to haemophilia treatment leading to fewer joint bleeds and, in some cases, no bleeding events, assessing whether current outcome assessment tools provide adequate sensitivity and specificity for management and care of patients with haemophilia is needed.

METHODS

An overview of current imaging tools for monitoring joint health, novel osteochondral damage and synovial proliferation biomarkers, and the relationship between assessments for functionality and imaging modalities is provided. Usefulness and sensitivity of point-of-care ultrasound (POCUS) to complement other assessments and use of ultrasound to monitor haemophilic arthropathy are also examined.

RESULTS

This review provides rationale for haemophilia teams to move beyond traditional outcomes in joint imaging, as well as guidance and evidence on assessment of joint health for potential new treatment modalities, such as gene therapy. The role of POCUS in the existing paradigm for haemophilia care and management along with the use of ultrasound as a complement to other outcome assessment tools are also discussed. Finally, the clinical effects of subclinical bleeding on joint function are described, to motivate screening for synovial proliferation.

CONCLUSION

POCUS can facilitate the early detection of joint damage and can monitor disease progression while providing insights into the efficacy of treatment regimens, and should be considered as an essential assessment tool for managing the care of patients with haemophilia.

Value of 3.0T MRI T2 mapping combined with SWI for the assessment of early lesions in hemophilic arthropathy

PURPOSE

To explore the value of magnetic resonance imaging (MRI) T2 mapping combined with susceptibility-weighted imaging (SWI) in detecting early cartilage damage and joint bleeding in the hemophilic arthropathy (HA).

METHODS

147 patients and 56 healthy controls were prospectively recruited. The knees were divided into groups A and B according to the criteria of the International Cartilage Repair Society (ICRS). The Regions of Interest (ROIs) of T2 mapping were drawn for the patella, lateral and medial femoral condyle, and lateral and medial tibial condyle. The T2 values were compared between the patients and control group using one-way ANOVA. The joint count data of International Prophylaxis Study Group (IPSG) scores of conventional and SWI sequences were statistically described using the composition ratio, and the rank sum test was used for the difference analysis.

RESULTS

Finally, there were 99 joints in the control group, 135 knees in group A, and 94 knees in group B. There was a significant difference between the T2 value in each subgroup. Comparison of T2 value groups in each cartilage partition, except for group A and group B of the patella, revealed significant differences (all P<0.05). SWI was likely more sensitive than conventional sequences in detecting hemosiderin deposits in hemophilic joints. In addition, the IPSG scores detected by the SWI were generally higher than those of conventional sequences.

CONCLUSIONS

MR T2 mapping combined with SWI has great potential to be used for detecting early cartilage damage and micro-hemosiderin deposition in hemophiliac arthropathies and developing preventative treatment plans.

Desferoxamine protects against hemophilic arthropathy through the upregulation of HIF-1α-BNIP3 mediated mitophagy

AIMS

Hemophilic arthropathy (HA) is a typically iron overload induced joint disease secondary to continuous joint bleeding, however, the exact role of iron chelators in HA has not been fully elucidated. In the present study, we investigated whether desferoxamine (DFO), an iron chelator, could limit the development of HA and the underlying mechanisms.

MATERIALS AND METHODS

A HA mice model was established by needle puncture in the left knees of FVIII-deficient hemophilic mice. HA progression was evaluated at 8 weeks after DFO administration. Moreover, chondrocytes were treated with ferric ammonium citrate (FAC) to mimic iron overload in vitro. Modulating effect of DFO on iron overload induced oxidative stress, chondrocytes apoptosis and extracellular matrix (ECM) degradation and the role of HIF-1α-BNIP3 mediated mitophagy were examined.

KEY FINDINGS

We found that DFO limited the development of HA and protected iron overload induced ECM degradation, chondrocytes apoptosis and oxidative stress. Besides chelating Fe²⁺, we found that HIF-1α-BNIP3 mediated mitophagy played important roles in the protective effect of DFO. HIF-1α inhibition suppressed chondrocytes mitophagy process and partly diminished the protective effect of DFO on chondrocytes iron overload.

SIGNIFICANCE

In conclusion, DFO could protect against HA development via HIF-1α-BNIP3 mediated mitophagy, suggesting DFO might be a potential therapeutic supplement for HA treatment.

Pain in Hemophilia: Unexplored Role of Oxidative Stress

Hemophilia is the most common X-linked bleeding diathesis caused by the genetic deficiency of coagulation factors VIII or IX. Despite treatment advances and improvements in clinical management to prevent bleeding, management of acute and chronic pain remains to be established. Repeated bleeding of the joints leads to arthropathy, causing pain in hemophilia. However, mechanisms underlying the pathogenesis of pain in hemophilia remain underexamined. Herein, we describe the novel perspectives on the role for oxidative stress in the periphery and the central nervous system that may contribute to pain in hemophilia. Specifically, we cross examine preclinical and clinical studies that address the contribution of oxidative stress in hemophilia and related diseases that affect synovial tissue to induce acute and potentially chronic pain. This understanding would help provide potential treatable targets using antioxidants to ameliorate pain in hemophilia.

Interplay Between Iron Overload and Osteoarthritis: Clinical Significance and Cellular Mechanisms

There are multiple diseases or conditions such as hereditary hemochromatosis, hemophilia, thalassemia, sickle cell disease, aging, and estrogen deficiency that can cause iron overload in the human body. These diseases or conditions are frequently associated with osteoarthritic phenotypes, such as progressive cartilage degradation, alterations in the microarchitecture and biomechanics of the subchondral bone, persistent joint inflammation, proliferative synovitis, and synovial pannus. Growing evidences suggest that the conditions of pathological iron overload are associated with these osteoarthritic phenotypes. Osteoarthritis (OA) is an important complication in patients suffering from iron overload-related diseases and conditions. This review aims to summarize the findings and observations made in the field of iron overload-related OA while conducting clinical and basic research works. OA is a whole-joint disease that affects the articular cartilage lining surfaces of bones, subchondral bones, and synovial tissues in the joint cavity. Chondrocytes, osteoclasts, osteoblasts, and synovial-derived cells are involved in the disease. In this review, we will elucidate the cellular and molecular mechanisms associated with iron overload and the negative influence that iron overload has on joint homeostasis. The promising value of interrupting the pathologic effects of iron overload is also well discussed for the development of improved therapeutics that can be used in the field of OA.

Articular Cartilage Assessment Using Ultrashort Echo Time MRI: A Review

Articular cartilage is a major component of the human knee joint which may be affected by a variety of degenerative mechanisms associated with joint pathologies and/or the aging process. Ultrashort echo time (UTE) sequences with a TE less than 100 µs are capable of detecting signals from both fast- and slow-relaxing water protons in cartilage. This allows comprehensive evaluation of all the cartilage layers, especially for the short T₂ layers which include the deep and calcified zones. Several ultrashort echo time (UTE) techniques have recently been developed for both morphological imaging and quantitative cartilage assessment. This review article summarizes the current catalog techniques based on UTE Magnetic Resonance Imaging (MRI) that have been utilized for such purposes in the human knee joint, such as T₁, T2∗ , T_1ρ, magnetization transfer (MT), double echo steady state (DESS), quantitative susceptibility mapping (QSM) and inversion recovery (IR). The contrast mechanisms as well as the advantages and disadvantages of these techniques are discussed.

Bleeding with iron deposition and vascular remodelling in subchondral cysts: A newly discovered feature unique to haemophilic arthropathy

INTRODUCTION

Joint iron accumulation is the incendiary factor triggering osteochondral destruction, synovial hypertrophy, inflammation, and vascular remodelling in haemophilic arthropathy (HA). Hemosiderin depositions have been described in synovium and, more recently, in cartilage. Clinical observations also suggest hemosiderin accumulation in subchondral cysts, implying cyst bleeding.

AIM

We explored associations between cystic iron accumulation, vascular remodelling and HA status to determine if cystic bleeding may contribute to HA progression.

METHODS

Thirty-six haemophilic joints (16 knees, 10 ankles, and 10 elbows; 31 adult patients with haemophilia A/B) were evaluated by magnetic resonance imaging (MRI) for subchondral cysts and hemosiderin. Cyst score (WORMS) and hemosiderin presence were compared between haemophilic and osteoarthritic knees, matched for the degree of arthritis (Kellgren-Lawrence score). Cystic iron accumulation, vascular remodelling and macrophage cell counts were also compared by immunohistochemistry in explanted joint tissues. In haemophilic knees, cyst number and extent of hemosiderin deposition were correlated with haemophilia joint health scores (HJHS).

RESULTS

Cystic hemosiderin was detected in 78% of haemophilic joints. Cyst score and presence of hemosiderin were significantly higher in haemophilic compared to osteoarthritic knees. Cyst score and presence of hemosiderin strongly correlated with HJHS. Moreover, iron deposition and vascular remodelling were significantly more pronounced within cysts in haemophilic compared to osteoarthritic knees, with similar total cell and macrophage count.

CONCLUSION

These findings suggest the presence of subchondral bleeding in haemophilia, contributing to poor joint health outcomes. Observations of bleeding into osseous structures are novel and should inform investigations of new therapies.

Musculoskeletal complications associated with pathological iron toxicity and its molecular mechanisms

Iron is fundamental for several biological functions, but when in excess can lead to the development of toxic events. Some tissues and cells are more susceptible than others, but systemic iron levels can be controlled by treating patients with iron-chelating molecules and phlebotomy. An early diagnostic can be decisive to limit the progression of musculoskeletal complications like osteoarthritis and osteoporosis because of iron toxicity. In iron-related osteoarthritis, aggravation can be associated to a few events that can contribute to joints articular cartilage exposure to high iron concentrations, which can promote articular degeneration with very little chance of tissue regeneration. In contrast, bone metabolism is much more dynamic than cartilage, but progressive iron accumulation and ageing can be decisive factors for bone health. The iron overload associated with hereditary diseases like hemochromatosis, hemophilias, thalassemias and other hereditary anaemias increase the negative impact of iron toxicity in joints and bone, as well as in life quality, even when iron levels can be controlled. The molecular mechanisms by which iron can compromise cartilage and bone have been illusive and only in the last 20 years studies have started to shed some light into the molecular mechanisms associated with iron toxicity. Ferroptosis and the regulation of intracellular iron levels is instrumental in the balance between detoxification and induced cell death. In addition, these complications are accompanied with multiple susceptibility factors that can aggravate iron toxicity and should be identified. Therefore, understanding tissues microenvironment and cell communication is fundamental to contextualize iron toxicity.

Asymptomatic Joint Bleeding and Joint Health in Hemophilia: A Review of Variables, Methods, and Biomarkers

Joint health is a key contributor to quality of life in patients with hemophilia. However, variables that impact long-term joint outcomes have not been comprehensively defined. A systematic literature search identified publications relating to joint health in patients with hemophilia. Studies clearly show that early, sustained prophylaxis with factor replacements improves long-term joint outcomes. However, a subset of patients appear to develop arthropathy despite maintaining excellent bleeding outcomes, which suggests possible recurrent asymptomatic bleeding into the joints in these patients. Furthermore, limited data are available on how long-acting factor VIII and factor IX replacement therapies could impact long-term joint outcomes. Many variables were identified as potential indicators that a patient may develop hemophilic arthropathy, including genetic mutations, endogenous factor VIII and IX levels, bone health, and physical activity levels. Tools for the diagnosis and monitoring of hemophilic arthropathy are critical to detect early joint damage, so that management can be adjusted accordingly. Imaging techniques, particularly magnetic resonance imaging, can detect synovial changes, a strong predictor for the future development of hemophilic arthropathy. In addition, several biomarkers associated with cartilage and bone formation, vascularization, and angiogenesis could potentially identify the onset and progression of early joint damage. Since the development of hemophilic arthropathy is complex, a comprehensive therapeutic approach is necessary for the effective prevention of arthropathy in patients with hemophilia.

Automated cartilage segmentation and quantification using 3D ultrashort echo time (UTE) cones MR imaging with deep convolutional neural networks

OBJECTIVE

To develop a fully automated full-thickness cartilage segmentation and mapping of T1, T1ρ, and T2*, as well as macromolecular fraction (MMF) by combining a series of quantitative 3D ultrashort echo time (UTE) cones MR imaging with a transfer learning-based U-Net convolutional neural networks (CNN) model.

METHODS

Sixty-five participants (20 normal, 29 doubtful-minimal osteoarthritis (OA), and 16 moderate-severe OA) were scanned using 3D UTE cones T1 (Cones-T1), adiabatic T1ρ (Cones-AdiabT1ρ), T2* (Cones-T2*), and magnetization transfer (Cones-MT) sequences at 3 T. Manual segmentation was performed by two experienced radiologists, and automatic segmentation was completed using the proposed U-Net CNN model. The accuracy of cartilage segmentation was evaluated using the Dice score and volumetric overlap error (VOE). Pearson correlation coefficient and intraclass correlation coefficient (ICC) were calculated to evaluate the consistency of quantitative MR parameters extracted from automatic and manual segmentations. UTE biomarkers were compared among different subject groups using one-way ANOVA.

RESULTS

The U-Net CNN model provided reliable cartilage segmentation with a mean Dice score of 0.82 and a mean VOE of 29.86%. The consistency of Cones-T1, Cones-AdiabT1ρ, Cones-T2*, and MMF calculated using automatic and manual segmentations ranged from 0.91 to 0.99 for Pearson correlation coefficients, and from 0.91 to 0.96 for ICCs, respectively. Significant increases in Cones-T1, Cones-AdiabT1ρ, and Cones-T2* (p < 0.05) and a decrease in MMF (p < 0.001) were observed in doubtful-minimal OA and/or moderate-severe OA over normal controls.

CONCLUSION

Quantitative 3D UTE cones MR imaging combined with the proposed U-Net CNN model allows a fully automated comprehensive assessment of articular cartilage.

KEY POINTS

• 3D UTE cones imaging combined with U-Net CNN model was able to provide fully automated cartilage segmentation. • UTE parameters obtained from automatic segmentation were able to reliably provide a quantitative assessment of cartilage.

Ultrashort echo time Cones double echo steady state (UTE-Cones-DESS) for rapid morphological imaging of short T2 tissues

PURPOSE

In this study, we aimed to develop a new technique, ultrashort echo time Cones double echo steady state (UTE-Cones-DESS), for highly efficient morphological imaging of musculoskeletal tissues with short T₂ s. We also proposed a novel, single-point Dixon (spDixon)-based approach for fat suppression.

METHODS

The UTE-Cones-DESS sequence was implemented on a 3T MR system. It uses a short radiofrequency (RF) pulse followed by a pair of balanced spiral-out and spiral-in readout gradients separated by an unbalanced spoiling gradient in-between. The readout gradients are applied immediately before or after the RF pulses to achieve a UTE image (S₊ ) and a spin/stimulated echo image (S_- ). Weighted echo subtraction between S₊ and S_- was performed to achieve high contrast specific to short T₂ tissues, and spDixon was applied to suppress fat by using the intrinsic complex signal of S₊ and S_- . Six healthy volunteers and five patients with osteoarthritis were recruited for whole-knee imaging. Additionally, two healthy volunteers were recruited for lower leg imaging.

RESULTS

The UTE-Cones-DESS sequence allows fast volumetric imaging of musculoskeletal tissues with excellent image contrast for the osteochondral junction, tendons, menisci, and ligaments in the knee joint as well as cortical bone and aponeurosis in the lower leg within 5 min. spDixon yields efficient fat suppression in both S₊ and S_- images without requiring any additional acquisitions or preparation pulses.

CONCLUSION

The rapid UTE-Cones-DESS sequence can be used for high contrast morphological imaging of short T₂ tissues, providing a new tool to assess their association with musculoskeletal disorders.

Ultrashort echo time quantitative susceptibility mapping (UTE-QSM) for detection of hemosiderin deposition in hemophilic arthropathy: A feasibility study

PURPOSE

The purpose of this study was to investigate the feasibility of ultrashort echo time quantitative susceptibility mapping (UTE-QSM) for assessment of hemosiderin deposition in the joints of hemophilic patients.

METHODS

The UTE-QSM technique was based on three sets of dual-echo 3D UTE Cones data acquired with TEs of 0.032/2.8, 0.2/3.6, and 0.4/4.4 ms. The images were processed with iterative decomposition of water and fat with echo asymmetry and least-squares estimation to estimate the B₀ field map in the presence of fat. Then, the projection onto dipole field (PDF) algorithm was applied to acquire a local field map generated by tissues, followed by application of the morphology-enabled dipole inversion (MEDI) algorithm to estimate a final susceptibility map. Three healthy volunteers and three hemophilic patients were recruited to evaluate the UTE-QSM technique's ability to assess hemosiderin in the knee or ankle joint at 3T. One patient subsequently underwent total knee arthroplasty after the MR scan. The synovial tissues harvested from the knee joint during surgery were processed for histological analysis to confirm iron deposition.

RESULTS

UTE-QSM successfully yielded tissue susceptibility maps of joints in both volunteers and patients. Multiple regions with high susceptibility over 1 ppm were detected in the affected joints of hemophilic patients, while no localized regions with high susceptibility were detected in asymptomatic healthy volunteers. Histology confirmed the presence of iron in regions where high susceptibility was detected by UTE-QSM.

CONCLUSION

The UTE-QSM technique can detect hemosiderin deposition in the joint, and provides a potential sensitive biomarker for the diagnosis and prognosis of hemophilic arthropathy.

Inhibition of Fenton reaction is a novel mechanism to explain the therapeutic effect of intra-articular injection of PRP in patients with chronic haemophilic synovitis

INTRODUCTION AND AIM

Haemarthroses cause major morbidity in haemophilia resulting in chronic haemophilic synovitis (CHS) and arthropathy. Oxidation of haemoglobin-coupled iron released in synovium after haemolysis induces chondrocytes death and cartilage damage, allowing postulate using iron-chelating drugs as potential therapeutic tool for haemophilic joint damage. Considering that albumin, the most abundant plasma protein, is a physiologic iron chelator, we aim to demonstrate that impediment of haemoglobin oxidation is exerted by plasma as a mechanism involved in the therapeutic effect of intra-articular injection of platelet-rich plasma in CHS.

METHODS

Oxidation of haemoglobin (Hb) to methaemoglobin (MeHb) through Fenton reaction was induced in vitro by addition of potassium ferricyanide in the presence or absence of peripheral blood-derived platelets-rich or platelets-poor plasma (PRP/PPP) or albumin. The relevance of in vitro findings was analysed in synovial fluid (SF) samples from one patient with CHS obtained before and after 6 months of PRP intra-articular injection.

RESULTS

MeHb formation was completely impaired either by of PPP, PRP or albumin indicating that PRP exerts an anti-oxidative effect, probably due by plasma albumin. Analysis of SF samples revealed the presence of MeHb levels and haemosiderin-laden macrophages in SF obtained before PRP treatment. Reduction of synovial MeHb, normalization of cellular composition and improvement of health joint haemophilic score, pain and bleeding episodes were registered after 6 months of PRP intra-articular injection.

CONCLUSION

Inhibition of Fenton reaction and the consequent normalization of joint cellular composition is a noncanonical mechanism underlying the therapeutic effect of PRP intra-articular injection in CHS.

To measure T1 of short T2 species using an inversion recovery prepared three-dimensional ultrashort echo time (3D IR-UTE) method: A phantom study

PURPOSE

To demonstrate the feasibility of a new method for measuring T₁ of short T₂ species based on an adiabatic inversion recovery-prepared three-dimensional ultrashort echo time Cones (3D IR-UTE-Cones) sequence.

METHODS

T₁ values for short T₂ species were quantified using 3D IR-UTE-Cones data acquired with different repetition times (TRs) and inversion times (TIs). An inversion efficiency factor Q was introduced into the fitting model to accurately calculate T₁ values for short T₂ species. Experiments were performed on twelve MnCl₂ aqueous solution phantoms with a wide range of T₁ values and T₂* values on a 3 T clinical MR system to verify the efficacy of the proposed method. For comparison, a variable flip angle UTE (VFA-UTE) sequence, a variable TR UTE (VTR-UTE) sequence, and a conventional 2D IR fast spin echo (IR-FSE) sequence were also used to quantify T₁ values of those phantoms. T₁ values were compared between all performed sequences.

RESULTS

The proposed 3D IR-UTE-Cones method provided higher contrast images of short T₂ phantoms and measured much shorter T₁ values than the VFA-UTE, VTR-UTE and 2D IR-FSE methods. T₁ values as short as 2.95 ms could be measured by the 3D IR-UTE-Cones sequence. The 3D IR-UTE-Cones methods with different TRs were applied to different ranges of T₁ measurement, and the scan time was significantly decreased by using 5 TIs along the recovery curves to perform fitting with comparable accuracy.

CONCLUSION

The 3D IR-UTE-Cones sequence could accurately measure short T₁ values while providing high contrast images of short T₂ species.