P031 Gout in the sterno-clavicular joint: a rare presentation mimicking thoracic outlet syndrome

For decades, dual-energy imaging has been used for tissue differentiation with several x-ray–based imaging modalities, exploiting the fact that the tissues in the human body show different absorption characteristics when penetrated with different x-ray spectra, spectra that are typically generated by different kV settings of the x-ray tube. Recently, dual-source computed tomography (CT) with 2 x-ray tubes and 2 detector arrays mounted in the same gantry has become available.1 After experience with earlier experimental prototypes, this dual-source CT for the first time enables the clinical acquisition of dual-energy CT studies simultaneously with a single scan. We used a dual-source CT scanner (Definition, Siemens, Forchheim, Germany) in dual-energy mode for performing coronary CT angiography in a 74-year–old woman with suspected coronary artery disease and prior abnormal nuclear rest/stress single-photon emission CT (SPECT). The CT scan was acquired with retrospective ECG-gating and the following scan parameters: 330-ms gantry rotation, pitch 0.2, and 32×2×0.6-mm …

Thoracic outlet syndrome may result from a posterior sternoclavicular (SC) joint subluxation, or an anterior SC joint subluxation after surgical fixation. This case report presents the physical therapy management of a patient with bilateral thoracic outlet syndrome (TOS) secondary to bilateral idiopathic anterior SC joint subluxation. A 16-year-old female presented with a 2-year history of numbness, tingling, and coldness in bilateral upper extremities, and intermittent headaches with occasional vision loss. Ipsilateral upper extremity symptoms were reproduced with cervical rotation and shoulder flexion and abduction from 90° to end of the range. All TOS tests were positive. Passive horizontal abduction, through the plane of scaption, produced anterior subluxation of the ipsilateral SC joint. Sustained posterior glides to the medial clavicle relieved all symptoms during shoulder flexion and the Adson's test. Interventions consisted of manual therapy, therapeutic exercise, and the trial of two orthoses. After 12 treatment sessions, the patient's symptoms resolved and she improved by 10 points on the Upper Extremity Functional Index. She had no reproduction of symptoms with the thoracic outlet special tests. She maintained a static hold for 90 sec at 90° shoulder flexion, 90° shoulder abduction, and full shoulder flexion without symptoms. The outcomes describe a successful intervention for a patient with bilateral TOS secondary to idiopathic bilateral anterior SC joint subluxation. This case suggests that SC joint dysfunction should be considered as a cause of TOS and should be screened during the initial examination.

BackgroundMonosodium urate (MSU) crystal deposits can be visualized and quantified with dual-energy CT (DECT) [1], with DECT studies showing an association between MSU deposition and bone erosion [2]. Pegloticase rapidly...

CSM 2014 Sports Physical Therapy Section Poster Presentations (Abstracts SPO1228–SPO1309, SPO6761)

POS0139 TWO-YEAR REDUCTION OF URATE LOAD IN DUAL-ENERGY CT DURING A TREAT-TO-TARGET APPROACH IN GOUT PATIENTS: RESULTS FROM A LONGITUDINAL STUDY (NOR-GOUT)

Objective : Dissolution velocity of monosodium urate (MSU) crystal during urate-lowering therapy (ULT) had been inadequately studied. By using dual-energy computed tomography (DECT), which allows accurate assessment of MSU load, we analyze relationship between serum urate (SU) and volumetric reduction rate of MSU and develop a model that predicts dissolution time. Methods Baseline and follow-up DECTs were performed under a standard ULT protocol. Monthly dissolution rates were calculated by simple and compound methods. Correlations with average SU were compared and analyzed. Best-fit regression model was identified. MSU dissolution times were plotted against SU at different endpoints. Results In 29 tophaceous gout patients, MSU volume reduced from baseline 10.94 ± 10.59 cm3 to 2.87 ± 5.27 cm3 on follow-up (p = .00). Dissolution rate had a stronger correlation with SU if calculated by compound method (Pearson’s correlation coefficient r= −0.77, p = .00) and was independent of baseline MSU load. The ensuing dissolution model was logarithmic and explained real-life scenarios. When SU > 0.43 mmol/l, dissolution time approached infinity. It improved to 10–19 months at SU = 0.24 mmol/l. When SU approximated zero (as with pegloticase), dissolution flattened and still took 4–8 months. Conclusion MSU dissolution is better described as a logarithmic function of SU, which explains, predicts, and facilitates understanding of the dissolution process.

OP0175 IDENTIFYING PERIPHERAL VASCULAR MONOSODIUM URATE CRYSTAL DEPOSITION WITH DUAL-ENERGY CT: FACT OR FICTION? THE VASCURATE STUDY

AB0934 DUAL-ENERGY COMPUTED TOMOGRAPHY IN GOUT PATIENTS: IS IT USEFUL IN GENERAL PRACTICE?

Patient: Female, 40Final Diagnosis: GoutSymptoms: Joint painMedication: —Clinical Procedure: Dual energy Computed tomographySpecialty: RheumatologyObjective:Rare co-existance of disease or pathologyBackground:Gout is characterized by deposition of uric acid crystals (monosodium urate) in tissues and fluids. This can cause acute inflammatory arthritis. The 2015 ACR/EULAR criteria for the diagnosis of gout include dual energy computed tomography (DECT)-demonstrated monosodium urate crystals as a new criterion. DECT is a spectral decomposition that permits recognition of different types of tissues based on their characteristic energy-dependent photon attenuation. A positive scan is defined as the presence of urate at articular or periarticular sites.Case Report:We describe a 51-year-old woman known to have anorexia nervosa. During our clinical examination, we detected plenty of tophi on both hands, but no swollen joints. The diagnosis of gout was made by visualizing crystals in a biopsy from a tophus. The first line of treatment was allopurinol, the second line was rasburicase, and the current treatment is febuxostat 80 mg/day, allopurinol 300 mg twice a day, and colchicine 0.5 mg twice a day. The patient has unchanged arthralgia and the size and number of tophi remain the same as before treatment in spite of active treatment for 3 years. Previously the patient had problems with adherence, but now she claims that she follows the proposed treatment. The last plasma urate (P-urate) was 0.57 mmol/L. Following two years of treatment, DECT of hands visualized monosodium urate crystal deposits in the tophi, as seen on the clinical photos, but also crystals in relation to the tendons and soft tissue.Conclusions:DECT is an imaging modality useful to assess urate crystal deposits at diagnosis of gout and could be considered during treatment evaluation. Lack of adherence to treatment should be considered when P-urate values vary significantly and when DECT scans over years persistently visualize monosodium urate crystals.

ABSTRACTBackground. Accurate stopping power estimation is crucial for treatment planning in proton therapy, and the uncertainties in stopping power are currently the largest contributor to the employed dose margins. Dual energy x-ray computed tomography (CT) (clinically available) and proton CT (in development) have both been proposed as methods for obtaining patient stopping power maps. The purpose of this work was to assess the accuracy of proton CT using dual energy CT scans of phantoms to establish reference accuracy levels.Material and methods. A CT calibration phantom and an abdomen cross section phantom containing inserts were scanned with dual energy and single energy CT with a state-of-the-art dual energy CT scanner. Proton CT scans were simulated using Monte Carlo methods. The simulations followed the setup used in current prototype proton CT scanners and included realistic modeling of detectors and the corresponding noise characteristics. Stopping power maps were calculated for all three scans, and compared with the ground truth stopping power from the phantoms.Results. Proton CT gave slightly better stopping power estimates than the dual energy CT method, with root mean square errors of 0.2% and 0.5% (for each phantom) compared to 0.5% and 0.9%. Single energy CT root mean square errors were 2.7% and 1.6%. Maximal errors for proton, dual energy and single energy CT were 0.51%, 1.7% and 7.4%, respectively.Conclusion. Better stopping power estimates could significantly reduce the range errors in proton therapy, but requires a large improvement in current methods which may be achievable with proton CT.

BackgroundProvisional gout remission criteria including five domains (serum urate, tophus, flares, pain due to gout, and patient global assessment) have been proposed. The aim of this study was to test the concurrent validity of the provisional gout remission criteria by comparing the criteria with dual-energy CT (DECT) findings.MethodsPatients with gout on allopurinol ≥ 300 mg daily were prospectively recruited into a multicenter DECT study. Participants attended a standardized study visit which recorded gout flare frequency in the preceding 12 months, physical examination for tophus, serum urate, and patient questionnaires. DECT scans of both hands/wrists, feet/ankles/Achilles, and knees were analyzed by two DECT radiologists. The relationship between the DECT urate crystal volume and deposition with individual domains as well as the provisional remission criteria set was analyzed.ResultsThe provisional remission criteria were fulfilled in 23 (15.1%) participants. DECT urate crystal deposition was observed less frequently in those fulfilling the provisional remission criteria (44%), compared with those not fulfilling the criteria (73.6%, odds ratio 0.28, P = 0.004). The median (range) DECT urate crystal volume was 0.00 (0.00–0.46) cm3 for those fulfilling the remission criteria, compared with 0.08 (0.00–19.53) cm3 for those not fulfilling the criteria (P = 0.002). In multivariate regression analysis, the serum urate and tophus domains were most strongly associated with DECT urate crystal deposition.ConclusionsIn people with gout established on allopurinol, a state of remission as defined by the provisional remission criteria is associated with less DECT urate crystal deposition. While this study provides support for the validity of the provisional gout remission criteria, it also demonstrates that some crystal deposition may be present in people achieving these criteria.

IntroductionDual-energy computed tomography (DECT) has potential for monitoring urate deposition in patients with gout. The aim of this prospective longitudinal study was to analyse measurement error of DECT urate volume measurement in clinically stable patients with tophaceous gout.MethodsSeventy-three patients with tophaceous gout on stable therapy attended study visits at baseline and twelve months. All patients had a comprehensive clinical assessment including serum urate testing and DECT scanning of both feet. Two readers analysed the DECT scans for the total urate volume in both feet. Analysis included inter-reader intraclass correlation coefficients (ICCs) and limits of agreement, and calculation of the smallest detectable change.ResultsMean (standard deviation) serum urate concentration over the study period was 0.38 (0.09) mmol/L. Urate-lowering therapy was prescribed in 70 (96%) patients. The median (interquartile range) baseline DECT urate volume was 0.49 (0.16, 2.18) cm3, and change in DECT urate volume was -0.01 (-0.40, 0.28) cm3. Inter-reader ICCs were 1.00 for baseline DECT volumes and 0.93 for change values. Inter-reader bias (standard deviation) for baseline volumes was -0.18 (0.63) cm3 and for change was -0.10 (0.93) cm3. The smallest detectable change was 0.91 cm3. There were 47 (64%) patients with baseline DECT urate volumes <0.91 cm3. Higher serum urate concentrations were observed in patients with increased DECT urate volumes above the smallest detectable change (P = 0.006). However, a relationship between changes in DECT urate volumes and serum urate concentrations was not observed in the entire group.ConclusionsIn patients with tophaceous gout on stable conventional urate-lowering therapy the measurement error for DECT urate volume assessment is substantially greater than the median baseline DECT volume. Analysis of patients commencing or intensifying urate-lowering therapy should clarify the optimal use of DECT as a potential outcome measure in studies of chronic gout.

To determine the clinical associations and predictive value of two thresholds of negative dual-energy CT (DECT) for MSU crystal deposition in gout patients initiating urate-lowering therapy (ULT) and identify which threshold is more clinically relevant. Patients from the CRYSTALILLE cohort with a diagnosis of gout naïve to ULT with baseline DECT scans of the knees and feet were selected. Two thresholds of positivity for DECT detection of MSU crystal deposition were considered (<0.01 cm3 and <0.1 cm3). Baseline characteristics and the prediction of key outcomes after ULT initiation, including reaching serum urate (SU) levels <6.0 and 5.0 mg/dl and occurrence of flares at 6, 12 and 24 months, associated with both thresholds of negative DECTs were compared with those of patients having positive DECT scans. A total of 211 patients, median age 66.2 years [interquartile range (IQR) 57-75.8], with a median symptom duration of 3 years (IQR 0-7.8) were included. A total of 38/211 (18%) and 90/211 (43%) had negative DECT scans for the 0.01 and 0.1 cm3 thresholds, respectively. Factors associated with negative DECT scans were younger age, shorter symptom duration and an absence of cardiovascular disease for both volume thresholds. A total of 9/39 (23.1%), 3/26 (11.5%) and 1/18 (5.6%) patients with <0.1 cm3 MSU crystals had flares at 6, 12 and 24 months, respectively, compared with 18/45 (40.0%), 9/36 (25.0%) and 2/18 (11.1%) patients with ≥0.1 cm3 (P > 0.05). Overall, 95 patients (68.3%) reached SU levels <6.0 mg/dl and 68 (48.9%) reached levels <5.0 mg/dl, without any difference between positive and negative DECTs, with ULT dosages that tended to be lower in patients with negative DECTs. The 0.1 cm3 threshold was better correlated with clinical presentation and evolution than the 0.01 cm3 threshold. Gout patients with negative DECTs exhibit milder disease and a lower comorbidity burden. They do not exhibit particularly easy-to-treat hyperuricaemia but they may have a lower risk of flares.

ObjectiveTo examine factors influencing the kinetics of monosodium urate (MSU) crystal dissolution measured with dual-energy computed tomography (DECT) during follow-up of patients with gout.MethodsPatients with a diagnosis of gout with...

Computed Tomography (CT) is the main modality used for the diagnosis and classification of hemorrhagic transformation (HT) after thrombectomy, however its reliability has shown limitations. Dual-energy CT (DECT) and magnetic resonance imaging (MRI) have been suggested to enhance the reliability of HT detection and classification, but direct three-way comparison of these modalities is lacking. To measure and compare the reliability of CT, DECT and MRI for the diagnosis, classification, and therapeutic consequences of HT after thrombectomy. Between June 2017 and September 2019, 66 of 324 patients included in the BP-TARGET trial underwent CT, DECT and MRI scans within 36 h after thrombectomy. Seven readers, including three neurologists, two diagnostic, and two interventional neuroradiologists independently reviewed the images. They were asked for each patient and each imaging modality to score the presence of a hemorrhagic transformation (of any type), the type of hemorrhagic transformation according to the European Cooperative Acute Stroke Study (ECASS), and whether they would start the patient on antiplatelet based on the imaging finding. The readers repeated the same readings 1 month later. Interrater and intrarater agreement were measured using Kappa statistics. There were frequent discrepancies between CT, DECT and MRI scans evaluations. The use of MRI led to an increased rate of HT diagnosis compared to CT and DECT scans. Interrater agreement for ECASS classification was only fair-to-moderate for all three imaging modalities but improved to a substantial level after dichotomization into 0/HI1/HI2 versus PH1/PH2. The interrater agreement for the decision to start antiplatelet therapy was substantial only with CT (κ = 0.636 [0.577-0.694]) and remained moderate with MRI and DECT. In our study, the imaging modality influenced the diagnosis and classification of HT, the management of antiplatelet therapy, and the interrater and intrarater agreement. These findings may guide the choice of imaging modality in research or clinical settings.