A Fast 3D Range-Modulator Delivery Approach: Validation of the FLUKA Model on a Varian ProBeam System Including a Robustness Analysis.

A 3D range-modulator (RM), optimized for a single energy and a specific target shape, is a promising and viable solution for the ultra-fast dose delivery in particle therapy. The aim of this work was to investigate the impact of potential beam and modulator misalignments on the dose distribution. Moreover, the FLUKA Monte Carlo model, capable of simulating 3D RMs, was adjusted and validated for the 250 MeV single-energy proton irradiation from a Varian ProBeam system. A 3D RM was designed for a cube target shape rotated 45° around two axes using a Varian-internal research version of the Eclipse treatment planning software, and the resulting dose distribution was simulated in a water phantom. Deviations from the ideal alignment were introduced, and the dose distributions from the modified simulations were compared to the original unmodified one. Finally, the FLUKA model and the workflow were validated with base-line data measurements and dose measurements of the manufactured modulator prototype at the HollandPTC facility in Delft. The adjusted FLUKA model, optimized particularly in the scope of a single-energy FLASH irradiation with a PMMA pre-absorber, demonstrated very good agreement with the measured dose distribution resulting from the 3D RM. Dose deviations resulting from modulator-beam axis misalignments depend on the specific 3D RM and its shape, pin aspect ratio, rotation angle, rotation point, etc. A minor modulator shift was found to be more relevant for the distal dose distribution than for the spread-out Bragg Peak (SOBP) homogeneity. On the other hand, a modulator tilt (rotation away from the beam axis) substantially affected not only the depth dose profile, transforming a flat SOBP into a broad, Gaussian-like distribution with increasing rotation angle, but also shifted the lateral dose distribution considerably. This work strives to increase awareness and highlight potential pitfalls as the 3D RM method progresses from a purely research concept to pre-clinical studies and human trials. Ensuring that gantry rotation and the combined weight of RM, PMMA, and aperture do not introduce alignment issues is critical. Given all the other range and positioning uncertainties, etc., not related to the modulator, the RM must be aligned with an accuracy below 1° in order to preserve a clinically acceptable total uncertainty budget. Careful consideration of critical parameters like the pin aspect ratio and possibly a novel robust modulator geometry optimization are potential additional strategies to mitigate the impact of positioning on the resulting dose. Finally, even the rotated cube 3D modulator with high aspect ratio pin structures (~80 mm height to 3 mm pin base width) was found to be relatively robust against a slight misalignment of 0.5° rotation or a 1.5 mm shift in one dimension perpendicular to the beam axis. Given a reliable positioning and QA concept, the additional uncertainties introduced by the 3D RM can be successfully managed adopting the concept into the clinical routine.

Radiation-induced DNA double-strand breaks in cortisol exposed fibroblasts as quantified with the novel foci-integrated damage complexity score (FIDCS).

Without the protective shielding of Earth's atmosphere, astronauts face higher doses of ionizing radiation in space, causing serious health concerns. Highly charged and high energy (HZE) particles are particularly effective in causing complex and difficult-to-repair DNA double-strand breaks compared to low linear energy transfer. Additionally, chronic cortisol exposure during spaceflight raises further concerns, although its specific impact on DNA damage and repair remains unknown. This study explorers the effect of different radiation qualities (photons, protons, carbon, and iron ions) on the DNA damage and repair of cortisol-conditioned primary human dermal fibroblasts. Besides, we introduce a new measure, the Foci-Integrated Damage Complexity Score (FIDCS), to assess DNA damage complexity by analyzing focus area and fluorescent intensity. Our results show that the FIDCS captured the DNA damage induced by different radiation qualities better than counting the number of foci, as traditionally done. Besides, using this measure, we were able to identify differences in DNA damage between cortisol-exposed cells and controls. This suggests that, besides measuring the total number of foci, considering the complexity of the DNA damage by means of the FIDCS can provide additional and, in our case, improved information when comparing different radiation qualities.

Evolution of Magnetic Resonance Imaging Lesions at the Sacroiliac Joints During and After Pregnancy by Serial Magnetic Resonance Imaging From Gestational Week Twenty to Twelve Months Postpartum.

OBJECTIVE: Sacroiliac (SI) joint magnetic resonance imaging (MRI) findings simulating sacroiliitis related to axial spondyloarthritis (SpA) may occur in women before and after birth. This study was undertaken to explore the prevalence, evolution, and topography of SI joint MRI lesions in pregnant and postpartum women. METHODS: A prospective cohort study included 103 first-time mothers who underwent up to 5 serial SI joint MRI between gestational week 20 and 12 months postpartum. After calibration, 3 assessors independently evaluated bone marrow edema (BME), including sacroiliitis according to the Assessment of SpondyloArthritis international Society (ASAS), as well as structural lesions, using the Spondyloarthritis Research Consortium of Canada (SPARCC) and a novel 2-plane assessment method. RESULTS: BME was frequent both during pregnancy and the postpartum period, peaking at 3 months postpartum with a prevalence of 69% (SPARCC) and 80% (2-plane method), but still present in 54% (SPARCC) and 58% (2-plane method) of subjects at 12 months postpartum. At 12 months postpartum, sacroiliitis according to the current ASAS definition was met in 41%, while 21% and 14% of women fulfilled the newly proposed ASAS MRI thresholds for active and structural SI joint lesions, respectively. BME clustered in the anterior middle joint portions at all time points, and ligamentous BME was rare. At 12 months postpartum, SPARCC erosion scores ≥3 (ASAS threshold) were observed in only 2.8% of women. CONCLUSION: At 12 months postpartum, 41% of women met the current ASAS sacroiliitis definition, which may result in false-positive assignments of axial SpA diagnosis in postpartum women with back pain. The topographical BME distribution and virtually absent erosions (ASAS threshold) at 12 months postpartum may help discriminate postpartum strain-related conditions from axial SpA-related sacroiliitis.

Potential benefits of using radioactive ion beams for range margin reduction in carbon ion therapy.

Sharp dose gradients and high biological effectiveness make ions such as 12C an ideal tool to treat deep-seated tumors, however, at the same time, sensitive to errors in the range prediction. Tumor safety margins mitigate these uncertainties, but during the irradiation they lead to unavoidable damage to the surrounding healthy tissue. To fully exploit the Bragg peak benefits, a large effort is put into establishing precise range verification methods. Despite positron emission tomography being widely in use for this purpose in 12C therapy, the low count rates, biological washout, and broad activity distribution still limit its precision. Instead, radioactive beams used directly for treatment would yield an improved signal and a closer match with the dose fall-off, potentially enabling precise in vivo beam range monitoring. We have performed a treatment planning study to estimate the possible impact of the reduced range uncertainties, enabled by radioactive 11C ions treatments, on sparing critical organs in tumor proximity. Compared to 12C treatments, (i) annihilation maps for 11C ions can reflect sub- millimeter shifts in dose distributions in the patient, (ii) outcomes of treatment planning with 11C significantly improve and (iii) less severe toxicities for serial and parallel critical organs can be expected.

Levels of extracellular matrix metabolites are associated with changes in Ankylosing Spondylitis Disease Activity Score and MRI inflammation scores in patients with axial spondyloarthritis during TNF inhibitor therapy.

BACKGROUND/PURPOSE: In axial spondyloarthritis (axSpA) inflammation of the sacroiliac joints and spine is associated with local extracellular matrix (ECM) remodeling of affected tissues. We aimed to investigate the association of ECM metabolites with treatment response in axSpA patients treated with TNF-α inhibitory therapy for 46 weeks. METHODS: In a prospective clinical study of axSpA patients (n=55) initiating a TNF inhibitor (infliximab, etanercept, or adalimumab), serum concentrations of formation of type I (PRO-C1), type III (PRO-C3), and type VI (PRO-C6) collagen; turnover of type IV collagen (PRO-C4), and matrix-metalloproteinase (MMP)-degraded type III (C3M) collagen, MMP-degraded type IV (C4M), type VI (C6M), and type VII (C7M) collagen, and cathepsin-degraded type X collagen (C10C), MMP-mediated metabolite of C-reactive protein (CRPM), citrullinated vimentin (VICM), and neutrophil elastase-degraded elastin (EL-NE) were measured at baseline, week 2, week 22, and week 46. RESULTS: Patients were mostly males (82%), HLA-B27 positive (84%), with a median age of 40 years (IQR: 32-48), disease duration of 5.5 years (IQR: 2-10), and a baseline Ankylosing Spondylitis Disease Activity Score (ASDAS) of 3.9 (IQR: 3.0-4.5). Compared to baseline, PRO-C1 levels were significantly increased after two weeks of treatment, C6M levels were significantly decreased after two and 22 weeks (repeated measures ANOVA, p=0.0014 and p=0.0015, respectively), EL-NE levels were significantly decreased after 2 weeks (p=0.0008), VICM levels were significantly decreased after two and 22 weeks (p=0.0163 and p=0.0374, respectively), and CRP were significantly decreased after two and 22 weeks (both p=0.0001). Baseline levels of PRO-C1, PRO-C3, C6M, VICM, and CRP were all associated with ASDAS clinically important and major improvement after 22 weeks (ΔASDAS ≥1.1) (Mann-Whitney test, p=0.006, p=0.008, p<0.001, <0.001, <0.001, respectively), while C6M, VICM and CRP levels were associated with ASDAS clinically important and major improvement after 46 weeks (ΔASDAS ≥2.0) (p=0.002, p=0.044, and p<0.001, respectively). PRO-C1 and C6M levels were associated with a Bath AS Disease Activity Score (BASDAI) response to TNF-inhibitory therapy after 22 weeks (Mann-Whitney test, p=0.020 and p=0.049, respectively). Baseline levels of PRO-C4 and C6M were correlated with the total SPARCC MRI Spine and Sacroiliac Joint Inflammation score (Spearman's Rho ρ=0.279, p=0.043 and ρ=0.496, p=0.0002, respectively). CONCLUSIONS: Extracellular matrix metabolites were associated with ASDAS response, MRI inflammation, and clinical treatment response during TNF-inhibitory treatment in patients with axSpA.

Roadmap: helium ion therapy.

Helium ion beam therapy for the treatment of cancer was one of several developed and studied particle treatments in the 1950s, leading to clinical trials beginning in 1975 at the Lawrence Berkeley National Laboratory. The trial shutdown was followed by decades of research and clinical silence on the topic while proton and carbon ion therapy made debuts at research facilities and academic hospitals worldwide. The lack of progression in understanding the principle facets of helium ion beam therapy in terms of physics, biological and clinical findings persists today, mainly attributable to its highly limited availability. Despite this major setback, there is an increasing focus on evaluating and establishing clinical and research programs using helium ion beams, with both therapy and imaging initiatives to supplement the clinical palette of radiotherapy in the treatment of aggressive disease and sensitive clinical cases. Moreover, due its intermediate physical and radio-biological properties between proton and carbon ion beams, helium ions may provide a streamlined economic steppingstone towards an era of widespread use of different particle species in light and heavy ion therapy. With respect to the clinical proton beams, helium ions exhibit superior physical properties such as reduced lateral scattering and range straggling with higher relative biological effectiveness (RBE) and dose-weighted linear energy transfer (LETd) ranging from ∼4 keVµm-1to ∼40 keVµm-1. In the frame of heavy ion therapy using carbon, oxygen or neon ions, where LETdincreases beyond 100 keVµm-1, helium ions exhibit similar physical attributes such as a sharp lateral penumbra, however, with reduced radio-biological uncertainties and without potentially spoiling dose distributions due to excess fragmentation of heavier ion beams, particularly for higher penetration depths. This roadmap presents an overview of the current state-of-the-art and future directions of helium ion therapy: understanding physics and improving modeling, understanding biology and improving modeling, imaging techniques using helium ions and refining and establishing clinical approaches and aims from learned experience with protons. These topics are organized and presented into three main sections, outlining current and future tasks in establishing clinical and research programs using helium ion beams-A. Physics B. Biological and C. Clinical Perspectives.

Ultra-High Dose Rate (FLASH) Carbon Ion Irradiation: Dosimetry and First Cell Experiments.

PURPOSE: To establish a beam monitoring and dosimetry system to enable the FLASH dose rate carbon ion irradiation and investigate, at different oxygen concentrations, the in vitro biological response in comparison to the conventional dose rate. METHODS AND MATERIALS: CHO-K1 cell response to irradiation at different dose rates and at different levels of oxygenation was studied using clonogenic assay. The Heidelberg Ion-Beam Therapy Center (HIT) synchrotron, after technical improvements, was adjusted to extract ≥5 × 108 12C ions within approximately 150 milliseconds. The beam monitors were filled with helium. RESULTS: The FLASH irradiation with beam scanning yields a dose of 7.5 Gy (homogeneity of ±5%) for a 280 MeV/u beam in a volume of at least 8 mm in diameter and a corresponding dose rate of 70 Gy/s (±20%). The dose repetition accuracy is better than 2%, the systematic uncertainty is better than 2%. Clonogenic assay demonstrates a significant FLASH sparing effect which is strongly oxygenation-dependent and mostly pronounced at 0.5% O2 but absent at 0% and 21% O2. CONCLUSION: The FLASH dose rates >40 Gy/s were achieved with carbon beams. Cell survival analysis revealed FLASH dose rate sparing in hypoxia (0.5%-4% O2).

Development and Validation of 3 Preliminary MRI Sacroiliac Joint Composite Structural Damage Scores in a 5-year Longitudinal Axial Spondyloarthritis Study.

OBJECTIVE: In axial spondyloarthritis (axSpA), sacroiliac joint (SIJ) erosion is often followed by fat metaplasia in an erosion cavity (backfill), and subsequently ankylosis. We aimed to combine the Spondyloarthritis Research Consortium of Canada (SPARCC) SIJ structural score for erosion, backfill, and ankylosis into 3 versions of a novel preliminary axSpA magnetic resonance imaging (MRI) SIJ Composite Structural Damage Score (CSDS) and to test these. METHODS: Thirty-three patients with axSpA, followed for 5 years after initiation of tumor necrosis factor inhibitor, had MRIs of the SIJs at baseline, and yearly thereafter. Three versions of CSDS were calculated based on different weightings of erosion, backfill, and ankylosis: (1) equal weighting: CSDSequal = (erosion × 0.5) + backfill + ankylosis; (2) advanced stages weighting more: CSDSstepwise = (erosion × 1) + (backfill × 4) + (ankylosis × 6); and (3) advanced stages overruling earlier stages ("hierarchical") with "<" meaning "overruled by": CSDShierarchical = (erosion × 1) < (backfill × 4) < (ankylosis × 6). RESULTS: At baseline, all CSDS correlated positively with SPARCC fat and ankylosis scores and modified New York radiography grading, and negatively with the Bath Ankylosing Spondylitis Disease Index and SPARCC SIJ inflammation scores. CSDSstepwise and CSDShierarchical (not CSDSequal) correlated positively with symptom duration and the Bath Ankylosing Spondylitis Metrology Index, and closer with SPARCC ankylosis score and modified New York radiography grading than CSDSequal. The adjusted annual progression rate for CSDSstepwise and CSDShierarchical (not CSDSequal) was higher the first year compared with fourth year (P = 0.04 and P = 0.01). Standardized response mean (baseline to Week 46) was moderate for CSDShierarchical (0.64) and CSDSstepwise (0.59) and small for CSDSequal (0.25). CONCLUSION: Particularly CSDSstepwise and CSDShierarchical showed construct validity and responsiveness, encouraging further validation in larger clinical trials. The potential clinical implication is assessment of SIJ damage progression by 1 composite score.

Utility of magnetic resonance imaging in Crohn's associated sacroiliitis: A cross-sectional study.

OBJECTIVE: Prevalence of sacroiliitis in Crohn's disease (CD) is variable depending on defining criteria. This study utilized standardized sacroiliac joint (SIJ) magnetic resonance imaging (MRI) to identify sacroiliitis in CD patients and its association with clinical and serological markers. METHODS: Consecutive adult subjects with CD prospectively enrolled from an inflammatory bowel disease clinic underwent SIJ MRI. Data collected included CD duration, history of joint/back pain, human leukocyte antigen-B27 status, Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Disease Activity Index, Harvey Bradshaw Index (HBI) for activity of CD, Ankylosing Spondylitis Disease Activity Score, and various serologic markers of inflammation. Three blinded readers reviewed MRIs for active and structural lesions according to the Spondyloarthritis Research Consortium of Canada modules. RESULTS: Thirty-three CD patients were enrolled: 76% female, 80% White, median age 36.4 years (interquartile range 27.2-49.0), moderate CD activity (mean HBI 8.8 ± SD 4.5). Nineteen subjects (58%) reported any back pain, 13 of whom had inflammatory back pain. Four subjects (12%) showed sacroiliitis using global approach and 6 (18%) met Assessment of SpondyloArthritis international Society MRI criteria of sacroiliitis. Older age (mean 51.2 ± SD 12.5 vs. 37.2 ± 14; P = .04), history of dactylitis (50.0% vs. 3.4%, P = .03) and worse BASMI (4.1 ± 0.7 vs. 2.4 ± 0.8, P ≤ .001) were associated with MRI sacroiliitis; no serologic measure was associated. CONCLUSION: There were 12%-18% of CD patients who had MRI evidence of sacroiliitis, which was not associated with back pain, CD activity or serologic measures. This data suggests that MRI is a useful modality to identify subclinical sacroiliitis in CD patients.

Data-driven definitions for active and structural MRI lesions in the sacroiliac joint in spondyloarthritis and their predictive utility.

OBJECTIVES: To determine quantitative SI joint MRI lesion cut-offs that optimally define a positive MRI for inflammatory and structural lesions typical of axial SpA (axSpA) and that predict clinical diagnosis. METHODS: The Assessment of SpondyloArthritis international Society (ASAS) MRI group assessed MRIs from the ASAS Classification Cohort in two reading exercises where (A) 169 cases and 7 central readers; (B) 107 cases and 8 central readers. We calculated sensitivity/specificity for the number of SI joint quadrants or slices with bone marrow oedema (BME), erosion, fat lesion, where a majority of central readers had high confidence there was a definite active or structural lesion. Cut-offs with ≥95% specificity were analysed for their predictive utility for follow-up rheumatologist diagnosis of axSpA by calculating positive/negative predictive values (PPVs/NPVs) and selecting cut-offs with PPV ≥ 95%. RESULTS: Active or structural lesions typical of axSpA on MRI had PPVs ≥ 95% for clinical diagnosis of axSpA. Cut-offs that best reflected a definite active lesion typical of axSpA were either ≥4 SI joint quadrants with BME at any location or at the same location in ≥3 consecutive slices. For definite structural lesion, the optimal cut-offs were any one of ≥3 SI joint quadrants with erosion or ≥5 with fat lesions, erosion at the same location for ≥2 consecutive slices, fat lesions at the same location for ≥3 consecutive slices, or presence of a deep (i.e. >1 cm depth) fat lesion. CONCLUSION: We propose cut-offs for definite active and structural lesions typical of axSpA that have high PPVs for a long-term clinical diagnosis of axSpA for application in disease classification and clinical research.

A modular dose delivery system for treating moving targets with scanned ion beams: Performance and safety characteristics, and preliminary tests.

PURPOSE: The purpose of this study was to develop a modular dose-delivery system (DDS) for scanned-ion radiotherapy that mitigates against organ motion artifacts by synchronizing the motion of the beam with that of the moving anatomy. METHODS: We integrated a new motion synchronization system and an existing DDS into two centers. The modular approach to integration utilized an adaptive layer of software and hardware interfaces. The method of synchronization comprised three major tasks, namely, the creation of 3D treatment plans (each representing one phase of respiratory motion and together comprising a 4D plan), monitoring anatomic motion during treatment, and synchronization of the beam to anatomic motion. The synchronization was accomplished in real time by repeatedly selecting and delivering a 3D plan, i.e., the one that most closely corresponded to the current anatomic state, until all plans were delivered. The performance characteristics of the motion mitigation system were tested by delivering 4D treatment plans to a moving phantom and comparing planned and measured dose distributions. Dosimetric performance was considered acceptable when the gamma-index pass rate was >90%, homogeneity-index value was >95%, and conformity-index value was >60%. Selected safety characteristics were tested by introducing errors during treatment and testing DDS response. RESULTS: Acceptable dosimetric performance and safety characteristics were observed for all treatment plans. CONCLUSIONS: We demonstrated, for the first time, that a modular prototype system, synchronizing scanned ion beams with moving targets can deliver conformal, motion-compensated dose distributions. The prototype system was implemented and characterized at GSI and CNAO.

MRI of the sacroiliac joints in athletes: recognition of non-specific bone marrow oedema by semi-axial added to standard semi-coronal scans.

OBJECTIVE: Assessment of combined semi-axial and semi-coronal SI joint MRI in two cohorts of young athletes to explore frequency and topography of non-specific bone marrow oedema (BMO), its association with four constitutional SI joint features, and potential restriction of false-positive assignments of Assessment of SpondyloArthritis International Society-defined sacroiliitis on standard semi-coronal scans alone. METHODS: Combined semi-axial and semi-coronal SI joint MRI scans of 20 recreational runners before/after running and 22 elite ice-hockey players were evaluated by three blinded readers for BMO and its association with four constitutional SI joint features: vascular partial volume effect, deep iliac ligament insertion, fluid-filled bone cyst and lumbosacral transitional anomaly. Scans of TNF-treated spondyloarthritis patients served to mask readers. We analysed distribution and topography of BMO and SI joint features across eight anatomical SI joint regions (upper/lower ilium/sacrum, subdivided in anterior/posterior slices) descriptively, as concordantly recorded by ⩾2/3 readers on both MRI planes. BMO confirmed on both scans was compared with previous evaluation of semi-coronal MRI alone, which met the Assessment of SpondyloArthritis International Society definition for active sacroiliitis. RESULTS: Perpendicular semi-axial and semi-coronal MRI scans confirmed BMO in the SI joint of every fourth young athlete, preferentially in the anterior upper sacrum. BMO associated with four constitutional SI joint features was observed in 20-36% of athletes, clustering in the posterior lower ilium. The proportion of Assessment of SpondyloArthritis International Society-positive sacroiliitis recorded on the semi-coronal plane alone decreased by 33-56% upon amending semi-axial scans. CONCLUSION: Semi-axial combined with standard semi-coronal scans in MRI protocols for sacroiliitis facilitated recognition of non-specific BMO, which clustered in posterior lower ilium/anterior upper sacrum.

Canada-Denmark MRI scoring system of the spine in patients with axial spondyloarthritis: updated definitions, scoring rules and inter-reader reliability in a multiple reader setting.

Objective: To validate the Canada-Denmark (CANDEN) MRI scoring system for the spine in axial spondyloarthritis with updated lesion definitions. Methods: Lesion definitions in the CANDEN system were updated and illustrated by a consensus set of reference images. Sagittal spine MRIs of 40 patients with axial spondyloarthritis obtained at baseline and at week 52 after initiation of treatment with the tumour necrosis factor inhibitor golimumab were evaluated in unknown chronology by seven readers blinded to all other data. Results: CANDEN MRI spine inflammation score had very good reliability for status scores (single-measure intraclass correlation coefficient (ICC) of 21 reader pairs median of 0.91 (IQR 0.88-0.92)) and change scores (ICC 0.88 (0.86-0.92)). CANDEN MRI spine fat score had good to very good reliability for status scores (ICC 0.79 (0.75-0.86)) and moderate to good reliability for detecting change (ICC 0.59 (0.46-0.73)). CANDEN MRI spine bone erosion score and CANDEN MRI spine new bone formation score had slight to moderate reliability for status scores (ICC 0.38 (0.32-0.52) and 0.39 (0.27-0.49), respectively). Conclusion: The CANDEN MRI spine scoring system allows a comprehensive evaluation of inflammation, fat, bone erosion and new bone formation of the spine in patients with axial spondyloarthritis. It demonstrated very good reliability for detecting change in inflammation, moderate to good reliability for detecting change in fat, and slight to moderate reliability for detecting bone erosions and new bone formation. Studies with longer follow-up or patients with more advanced spinal involvement may be needed to reliably detect change in bone erosion and new bone formation scores. Trial registration number: NCT02011386.

MRI lesions in the sacroiliac joints of patients with spondyloarthritis: an update of definitions and validation by the ASAS MRI working group.

OBJECTIVES: The Assessment of SpondyloArthritis international Society (ASAS) MRI working group (WG) was convened to generate a consensus update on standardised definitions for MRI lesions in the sacroiliac joint (SIJ) of patients with spondyloarthritis (SpA), and to conduct preliminary validation. METHODS: The literature pertaining to these MRI lesion definitions was discussed at three meetings of the group. 25 investigators (20 rheumatologists, 5 radiologists) determined which definitions should be retained or required revision, and which required a new definition. Lesion definitions were assessed in a multi-reader validation exercise using 278 MRI scans from the ASAS classification cohort by global assessment (lesion present/absent) and detailed scoring (inflammation and structural). Reliability of detection of lesions was analysed using kappa statistics and the intraclass correlation coefficient (ICC). RESULTS: No revisions were made to the current ASAS definition of a positive SIJ MRI or definitions for subchondral inflammation and sclerosis. The following definitions were revised: capsulitis, enthesitis, fat lesion and erosion. New definitions were developed for joint space enhancement, joint space fluid, fat metaplasia in an erosion cavity, ankylosis and bone bud. The most frequently detected structural lesion, erosion, was detected almost as reliably as subchondral inflammation (κappa/ICC:0.61/0.54 and 0.60/0.83) . Fat metaplasia in an erosion cavity and ankylosis were also reliably detected despite their low frequency (κappa/ICC:0.50/0.37 and 0.58/0.97). CONCLUSION: The ASAS-MRI WG concluded that several definitions required revision and some new definitions were necessary. Multi-reader validation demonstrated substantial reliability for the most frequently detected lesions and comparable reliability between active and structural lesions.

What Level of Inflammation Leads to Structural Damage in the Sacroiliac Joints? A Four-Year Magnetic Resonance Imaging Follow-Up Study of Low Back Pain Patients.

OBJECTIVE: Sacroiliac (SI) joint bone marrow edema (BME) is considered to be pivotal in the detection of early spondyloarthritis. However, the link between BME and development of spondyloarthritis-related bone remodeling remains unclear. This study was undertaken to investigate the evolution of BME and structural lesions in the SI joints over time. METHODS: Baseline and 4-year follow-up magnetic resonance imaging scans were conducted in 604 patients ages 18-40 years who were referred with low back pain to an outpatient spine clinic. Eight SI joint regions were scored for BME and categorized as absent, limited (<25% of subcortical bone region), intermediate (25-50%), or extensive (>50%). Structural lesions including erosions and fat lesions were scored as absent or present. RESULTS: SI joint BME was seen at either time point (baseline or at 4 years) in 41% of participants but was persistent at both time points in only 16% of participants. Structural SI joint lesions developed according to the extent of BME at baseline: limited, intermediate, and extensive BME (as compared to absent BME) were independently associated with erosion at follow-up with odds ratios (ORs) of 3, 5, and 46, respectively, and with fat lesions (ORs 3, 7, and 33, respectively). In regions with limited and intermediate BME at baseline, 60% and 50% had resolved by follow-up, respectively, while only 2% and 7% had evolved into extensive BME by follow-up. CONCLUSION: While extensive SI joint BME was a strong independent predictor of development of structural lesions, limited and intermediate BME were mostly transient and only rarely evolved into extensive BME or structural lesions. These findings enhance our understanding of the natural development of SI joint lesions and indicate different progression patterns for limited/intermediate versus extensive BME, possibly due to different etiologies.

A new facility for proton radiobiology at the Trento proton therapy centre: Design and implementation.

We present a new facility dedicated to radiobiology research, which has been implemented at the Trento Proton Therapy Centre (Italy). A dual-ring double scattering system was designed to produce irradiation fields of two sizes (i.e. 6 and 16 cm diameter) starting from a fix pencil beam at 148 MeV. The modulation in depth was obtained with a custom-made range modulator, optimized to generate a 2.5 cm spread-out Bragg peak (SOBP). The resulting irradiation field was characterized in terms of lateral and depth-dose profiles. The beam characteristics and the geometry of the setup were implemented in the Geant4 Monte Carlo (MC) code. After benchmark against experimental data, the MC was used to characterize the distribution of dose-average linear energy transfer (LET) associated to the irradiation field. The results indicate that dose uniformity above 92.9% is obtained at the entrance channel as well as in the middle SOBP in the target regions for both irradiation fields. Dose rate in the range from 0.38 to 0.78 Gy/min was measured, which can be adjusted by proper selection of cyclotron output current, and eventually increased by about a factor 7. MC simulations were able to reproduce experimental data with good agreement. The characteristics of the facility are in line with the requirements of most radiobiology experiments. Importantly, the facility is also open to external users, after successful evaluation of beam proposals by the Program Advisory Committee.

OMERACT Hip Inflammation Magnetic Resonance Imaging Scoring System (HIMRISS) Assessment in Longitudinal Study.

OBJECTIVE: To assess reliability, feasibility, and responsiveness of Hip Inflammation Magnetic resonance imaging Scoring System (HIMRISS) for bone marrow lesions (BML) in hip osteoarthritis (OA). METHODS: HIMRISS was scored by 8 readers in 360 hips of 90 patients imaged pre/post-hip steroid injection. Pre-scoring, new readers trained online to achieve intraclass correlation coefficient (ICC) > 0.80 versus experts. RESULTS: HIMRISS reliability was excellent for BML status (ICC 0.83-0.92). Despite small changes post-injection, reliability of BML change scores was high in femur (0.76-0.81) and moderate in acetabulum (0.42-0.56). CONCLUSION: HIMRISS should be a priority for further assessment of hip BML in OA, and evaluated for use in other arthropathies.

Do Patients With Skin Psoriasis Show Subclinical Axial Inflammation on Magnetic Resonance Imaging of the Sacroiliac Joints and Entire Spine?

OBJECTIVE: To explore potential subclinical involvement of the axial skeleton by magnetic resonance imaging (MRI) of the sacroiliac (SI) joints and the entire spine in patients with skin psoriasis without clinical evidence of peripheral or axial inflammation. METHODS: Twenty patients with skin psoriasis but no clinical evidence of peripheral or axial inflammation and 22 healthy controls underwent standardized dermatologic and rheumatologic clinical examination and unenhanced 1.5T MRI of the SI joint and the entire spine. Two blinded readers globally assessed the presence or absence of SI joint inflammation simultaneously on T1-weighted and short tau inversion recovery MRI sequences with a confidence estimate. Bone marrow edema, fat metaplasia, erosion, and ankylosis of the SI joint, and vertebral corner inflammatory lesions and fat lesions were recorded using standardized modules. The prevalence of each lesion type was calculated in both groups, averaged across 2 readers. The number of subjects with lesions in the SI joint and spine (≥1, 2, 3, 4, or 5 lesions) as concordantly assessed by both readers was recorded. RESULTS: The median duration of skin psoriasis was 23.0 years, the median age of patients was 48.5 years, and 25.0% of patients and 9.1% of healthy controls were concordantly classified by both readers as having SI joint inflammation (P = 0.23). The prevalence of bone marrow edema and structural lesions was comparable across patients and controls, both on SI joint and spine MRI. CONCLUSION: In this controlled study, patients with skin psoriasis but no clinical arthritis or spondylitis showed limited evidence of concomitant subclinical axial involvement by SI joint and spine MRI. These findings do not support routine screening for subclinical axial inflammation in patients with longstanding skin psoriasis.

A Novel Approach To Quantify Air-Water Gas Exchange in Shallow Surface Waters Using High-Resolution Time Series of Dissolved Atmospheric Gases.

Gas exchange across the air-water interface is a key process determining the release of greenhouse gases from surface waters and a fundamental component of gas dynamics in aquatic systems. To experimentally quantify the gas transfer velocity in a wide range of aquatic settings, a novel method based on recently developed techniques for the in situ, near-continuous measurement of dissolved (noble) gases with a field portable mass spectrometer is presented. Variations in observed dissolved gas concentrations are damped and lagged with respect to equilibrium concentrations, being the result of (a) temperature (and thus solubility) variations, (b) water depth, and (c) the specific gas transfer velocity ( ki). The method fits a model to the measured gas concentrations to derive the gas transfer velocity from the amplitude and the phase lag between observed and equilibrium concentrations. With the current experimental setup, the method is sensitive to gas transfer velocities of 0.05-9 m/day (for N2), at a water depth of 1 m, and a given daily water temperature variation of 10 °C. Experiments were performed (a) in a controlled experiment to prove the concept and to confirm the capability to determine low transfer velocities and (b) in a field study in a shallow coastal lagoon covering a range of transfer velocities, demonstrating the field applicability of the method.

Response to Tumor Necrosis Factor Inhibition in Male and Female Patients with Ankylosing Spondylitis: Data from a Swiss Cohort.

OBJECTIVE: To investigate sex differences in connection with the effectiveness of tumor necrosis factor inhibitors (TNFi) in patients with ankylosing spondylitis (AS). METHODS: A total of 440 patients with AS (294 men; 146 women) initiating a first TNFi in the prospective Swiss Clinical Quality Management Cohort were included. We evaluated the proportion of patients achieving the 20% and 40% improvement in the Assessment of Spondyloarthritis international Society criteria (ASAS20 and ASAS40) as well as Ankylosing Spondylitis Disease Activity Score (ASDAS) improvement and status scores at 1 year. Patients having discontinued TNFi were considered nonresponders. Logistic regression analyses were performed to adjust for important predictors of response. RESULTS: Compared to men, female patients had lower mean C-reactive protein levels, better spinal mobility, and more peripheral disease at the start. There was no sex disparity with regard to the ASDAS, the Bath Ankylosing Spondylitis Disease Activity and Functional indices, and the quality of life. At 1 year, 52% of women and 63% of men achieved an ASAS20 response (OR 0.63, 95% CI 0.37-1.07, p = 0.09). An inactive disease status (ASDAS < 1.3) was reached by 18% of women and 26% of men (OR 0.65, 95% CI 0.32-1.27, p = 0.22). These sex differences in response to TNFi were more pronounced in adjusted analyses (OR 0.34, 95% CI 0.16-0.71, p = 0.005 for ASAS20 and OR 0.10, 95% CI 0.03-0.31, p < 0.001 for ASDAS < 1.3) and confirmed for all the other outcomes assessed. CONCLUSION: In AS, fewer women respond to TNFi and women show a reduced response in comparison to men.