Shark depredation: future directions in research and management.

Shark depredation is a complex social-ecological issue that affects a range of fisheries worldwide. Increasing concern about the impacts of shark depredation, and how it intersects with the broader context of fisheries management, has driven recent research in this area, especially in Australia and the United States. This review synthesises these recent advances and provides strategic guidance for researchers aiming to characterise the occurrence of depredation, identify the shark species responsible, and test deterrent and management approaches to reduce its impacts. Specifically, the review covers the application of social science approaches, as well as advances in video camera and genetic methods for identifying depredating species. The practicalities and considerations for testing magnetic, electrical, and acoustic deterrent devices are discussed in light of recent research. Key concepts for the management of shark depredation are reviewed, with recommendations made to guide future research and policy development. Specific management responses to address shark depredation are lacking, and this review emphasizes that a "silver bullet" approach for mitigating depredation does not yet exist. Rather, future efforts to manage shark depredation must rely on a diverse range of integrated approaches involving those in the fishery (fishers, scientists and fishery managers), social scientists, educators, and other stakeholders.

Anatomic accuracy of airway training manikins compared with humans.

Airway simulators, or training manikins, are frequently used in research studies for device development and training purposes. This study was designed to determine the anatomic accuracy of the most frequently used low-fidelity airway training manikins. Computerised tomography scans and ruler measurements were taken of the SynDaver® , Laerdal® and AirSim® manikins. These measurements were compared with human computerised tomography (CT) scans (n = 33) from patients at the University of Michigan Medical Center or previously published values. Manikin measurements were scored as a percentile among the distribution of the same measurements in the human population and 10 out of 27 manikin measurements (nine measurements each in three manikins) were outside of two standard deviations from the mean in the participants. All three manikins were visually identifiable as outliers when plotting the first two dimensions from multidimensional scaling. In particular, the airway space between the epiglottis and posterior pharyngeal wall, through which airway devices must pass, was too large in all three manikins. SynDaver, Laerdal and AirSim manikins do not have anatomically correct static dimensions in relation to humans and these inaccuracies may lead to imprecise airway device development, negatively affect training and cause over-confidence in users.

A comparison of ultrasound-guided rotator interval and posterior glenohumeral injection techniques for MR shoulder arthrography.

PURPOSE: The aim of this prospective, randomized study was to compare the performance of a rotator interval approach with the posterior glenohumeral approach for ultrasound-guided contrast injection prior to MR shoulder arthrography. METHOD: This study was approved by the institutional review board. One hundred and twenty consecutive patients referred for MR shoulder arthrography were randomized into four groups: rotator interval approach in-plane (n = 30); rotator interval approach out-of-plane (n = 30); posterior approach in-plane (n = 30); and posterior approach out-of plane (n = 30). Outcome measures included procedure time, number of injection attempts, patient-reported pain score (0-10), and radiologist-reported technical difficulty (0-10). MR arthrograms were assessed for adequacy of joint distension, diagnostic utility, and extra-capsular contrast leakage. RESULTS: All 120 patients had a successful ultrasound-guided injection with adequate joint distension and diagnostic utility for MR arthrography. In-plane needle guidance was less technically demanding, quicker, required fewer injection attempts, and had a lower frequency of contrast leakage than out-of-plane needle guidance. The posterior glenohumeral approach was less technically demanding though had a higher frequency of contrast leakage and caused more patient discomfort than the rotator interval approach. CONCLUSION: For ultrasound-guided shoulder joint injection, an in-plane approach is preferable. The posterior glenohumeral approach is less technically demanding though causes more patients discomfort than the rotator interval approach possibly due to the longer needle path.

Accuracy of ultrasound in the characterisation of deep soft tissue masses: a prospective study.

PURPOSE: To investigate the accuracy of ultrasound in characterising the type of mass and likelihood of malignancy in deep soft tissue masses. METHODS: Five hundred seventy-nine deep soft tissue masses were prospectively studied by ultrasound. Masses (n = 137) with prior MRI or CT were not included. Following ultrasound examination, the likely nature of the mass as well as the confidence of the reporting radiologist ('fully confident' versus 'not fully confident') about the ultrasound diagnosis was recorded. Clinical and ultrasound diagnoses were compared with the histological diagnosis which was available in 134 (23%) of the 579 masses. RESULTS: Compared with histology, clinical and ultrasound accuracy for characterising the type of mass were 47% and 88% respectively when all differential diagnoses were considered. The radiologist was fully confident regarding the type of 436 (75%) of 579 masses and, in this setting, for those cases that could be compared with histology, diagnostic accuracy was 96%. For the remaining masses, where the radiologist was not fully confident, accuracy compared with histology was 58% for the first differential diagnosis and 80% for all differential diagnoses. For identifying malignancy, sensitivity, specificity, and positive and negative predictive value of ultrasound were 97%, 58%, 67%, and 99% respectively. Ultrasound alone was considered sufficient for diagnostic workup in over half of all deep soft tissue masses. CONCLUSION: Ultrasound is useful at characterising and recognising malignancy in deep soft tissue masses. Provided local practice patterns are favourable, ultrasound may be considered a first-line investigation in the diagnostic workup of deep soft tissue masses. KEY POINTS: • In three-quarters of cases, one can be fully confident about characterising the nature of deep soft tissue masses on ultrasound and, for those fully confident cases that could be compared with histology, the diagnostic accuracy of ultrasound was 96%. • Ultrasound can correctly recognise nearly all malignant deep soft tissue masses but some benign masses will also be considered possibly malignant. • Ultrasound alone was considered sufficient for imaging workup in over half of deep soft tissue masses.

General Data Protection Regulation (GDPR) in Healthcare: Hot Topics and Research Fronts.

General Data Protection Regulation came into effect across the European Union in May 2018 but its implications in healthcare are yet to be fully understood. The aim of this study was to identify the fronts and hot topics in research on GDPR in healthcare. We analyzed the relevant records in Scopus through bibliometric and scientometric approach and visualization techniques. A set of 155 records was obtained and processed for co-occurrence analysis of key terms and concept mapping. The number of published papers showed a steep rise in the past two years, mainly by European countries. Analysis of the abstract of the papers showed that data protection, privacy, and big data were the most frequently used terms. Three dominant research fronts of GDPR are 1) general implications of GDPR, 2) technology aspects of GDPR, and 3) GDPR in healthcare service. Blockchain and machine learning are among the remerging topics of GDPR research.

ERAMRS: a new MR scoring system for early rheumatoid arthritis of the wrist.

PURPOSE: To (i) devise a new semi-quantitative scoring system known as Early Rheumatoid Arthritis Magnetic Resonance Score (ERAMRS) to assess inflammation of the wrist on magnetic resonance imaging in early rheumatoid arthritis and to (ii) test ERAMRS and other MR scoring systems against everyday used clinical scorings. MATERIALS AND METHODS: One hundred six treatment-naïve patients (81 females, 25 males, mean age 53 ± 12 years) with early rheumatoid arthritis (ERA) underwent clinical/serological testing as well as 3-T MRI examination of the most symptomatic wrist. Clinical assessment included Disease Activity Score-28 and Health Assessment Questionnaire; erythrocyte sedimentation rate and C-reactive protein were measured. MR imaging data was scored in all patients using three devised MR semi-quantitative scoring systems, namely, the (a) ERAMRS system, (b) Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) system, and the (c) McQueen Score system. RESULTS: Synovitis was present in 106 (100%), tenosynovitis in 98 (92%), and bone marrow edema in 84 (79%) of 106 ERA wrists. ERAMRS had the highest correlation with clinical disease activity scores (r = 0.476, p < 0.001) and serological parameters (r = 0.562, p < 0.001). RAMRIS system had the lowest correlation (r = 0.369, p < 0.001 for clinical disease activity; r = 0.436, p < 0.001 for serological parameters). RAMRIS synovitis subscore had a lower correlation than ERAMRS for clinical disease activity (r = 0.410, p < 0.001) and for serological parameters (r = 0.456, p < 0.001). CONCLUSION: The ERAMRS system, designed to grade inflammation on wrist MRI in ERA, provided the best correlation with all clinical scoring systems and serological parameters, indicating its improved clinical relevance over other MR scoring systems. KEY POINTS: • We devised a clinically relevant, easy-to-use semi-quantitative scoring system for scoring inflammation on MRI of the wrist in patients with early rheumatoid arthritis. • ERAMRS system showed better correlation with all clinical and serological assessment of inflammation in patients with early rheumatoid arthritis indicating its improved clinical relevance over other MR scoring systems.

Using spectral reflectance to distinguish between tracheal and oesophageal tissue: applications for airway management.

Proper placement of the tracheal tube requires confirmation, and the predominant method in addition to clinical signs is the presence of end-tidal carbon dioxide. Such is the importance of confirmation that novel methods may also have a place. We previously demonstrated using ex-vivo swine tissue a unique spectral reflectance characteristic of tracheal tissue that differs from oesophageal tissue. We hypothesised that this characteristic would be present in living swine tissue and human cadavers. Reflectance spectra in the range 500-650 nm were captured using a customised fibreoptic probe, compact spectrometer and white light source from both the trachea and the oesophagus in anesthetised living swine and in human cadavers. A tracheal detection algorithm using ratio comparisons of reflectance was developed. The existence of the unique tracheal characteristic in both in-vivo swine and cadaver models was confirmed (p < 0.0001 for all comparisons between tracheal and oesophageal tissue at all target wavelengths in both species). Furthermore, our proposed tracheal detection algorithm exhibited a 100% positive predictive value in both models. This has potential utility for incorporation into airway management devices.

Cross-sectional area of the median nerve at the wrist: Comparison of sonographic, MRI, and cadaveric measurements.

BACKGROUND: This study compares median nerve cross-sectional area (CSA) measurements at the wrist obtained with ultrasound (US) and magnetic resonance imaging (MRI) using cadaveric measurements as the gold standard. METHODS: Median nerve CSA was measured using US and MRI in 9 cadaveric wrists obtained from 5 subjects at 5 locations: distal forearm, proximal to tunnel inlet, at tunnel inlet, at tunnel outlet, and distal to tunnel outlet and then on identical cadaveric transverse sections obtained with a bandsaw. All US, MRI, and cadaveric measurements were repeated to determine reliability. Median nerves of 10 patients with clinical carpal tunnel syndrome (CTS) were measured with US and MRI using an identical method US. RESULTS: Median nerve CSA MRI measurements correlated better (Pearson correlation: 0.80-0.95, P < .05) with cadaveric measurements than with US measurements (Pearson correlation: 0.61-0.79, P < .05). Median nerve CSA US measurements (8.6-12.5 mm2 , P < .05) were smaller at all levels than MRI (11.3-14.7 mm2 ) or cadaveric (11.0-14.9 mm2 ) measurements while MRI and cadaver measurements were similar at all levels. Median nerve CSA MRI measurements in CTS patients were larger than US measurements at all levels. CONCLUSION: Median nerve CSA measurements by MRI are larger than US measurements and correlated better with cadaveric measurements. Median nerve CSA criteria used for diagnosing CTS on US are not likely to be applicable to MRI.

The Additional Contribution of White Matter Hyperintensity Location to Post-stroke Cognitive Impairment: Insights From a Multiple-Lesion Symptom Mapping Study.

White matter hyperintensities (WMH) are common in acute ischemic stroke patients. Although WMH volume has been reported to influence post-stroke cognition, it is still not clear whether WMH location, independent of acute ischemic lesion (AIL) volume and location, contributes to cognitive impairment after stroke. Here, we proposed a multiple-lesion symptom mapping model that considers both the presence of WMH and AIL to measure the additional contribution of WMH locations to post-stroke cognitive impairment. Seventy-six first-ever stroke patients with AILs in the left hemisphere were examined by Montreal Cognitive Assessment (MoCA) at baseline and 1 year after stroke. The association between the location of AIL and WMH and global cognition was investigated by a multiple-lesion symptom mapping (MLSM) model based on support vector regression (SVR). To explore the relative merits of MLSM over the existing lesion-symptom mapping approaches with only AIL considered (mass-univariate VLSM and SVR-LSM), we measured the contribution of the significant AIL and/or WMH clusters from these models to post-stroke cognitive impairment. In addition, we compared the significant WMH locations identified by the optimal SVR-MLSM model for cognitive impairment at baseline and 1 year post stroke. The identified strategic locations of WMH significantly contributed to the prediction of MoCA at baseline (short-term) and 1 year (long-term) after stroke independent of the strategic locations of AIL. The significant clusters of WMH for short-term and long-term post-stroke cognitive impairment were mainly in the corpus callosum, corona radiata, and posterior thalamic radiation. We noted that in some regions, the AIL clusters that were significant for short-term outcome were no longer significant for long-term outcome, and interestingly more WMH clusters in these regions became significant for long-term outcome compared to short-term outcome. This indicated that there are some regions where local WMH burden has larger impact than AIL burden on the long-term post-stroke cognitive impairment. In consequence, SVR-MLSM was effective in identifying the WMH locations that have additional impact on post-stroke cognition on top of AIL locations. Such a method can also be applied to other lesion-behavior studies where multiple types of lesions may have potential contributions to a specific behavior.

MR imaging of the traumatic triangular fibrocartilaginous complex tear.

Triangular fibrocartilage complex is a major stabilizer of the distal radioulnar joint (DRUJ). However, triangular fibrocartilage complex (TFCC) tear is difficult to be diagnosed on MRI for its intrinsic small and thin structure with complex anatomy. The purpose of this article is to review the anatomy of TFCC, state of art MRI imaging technique, normal appearance and features of tear on MRI according to the Palmar's classification. Atypical tear and limitations of MRI in diagnosis of TFCC tear are also discussed.

Effect of traction on wrist joint space and cartilage visibility with and without MR arthrography.

OBJECTIVE: To compare the effect of traction during non-arthrographic and arthrographic MR examination of the wrist with regard to joint space width, joint fluid dispersion and cartilage surface visibility. METHODS: Prospective 3-T MRI study of 100 wrists in 96 patients. The first 50 wrists underwent MR arthrography first without traction and then with traction. The following 50 wrists underwent standard MR first without traction and then with traction. On these examinations, two radiologists independently measured (i) joint space width, semi-quantitatively graded (ii) joint fluid dispersion between opposing cartilage surfaces and (iii) articular cartilage surface visibility. The three parameters were compared between the two groups. RESULTS: Traction led to an increase in joint space width at nearly all joints in all patients (p < 0.05), although more so in the arthrography (∆ = 0.08-0.79 mm, all p < 0.05) than in the non-arthrography (∆ = 0.001-0.61 mm, all p < 0.05) group. Joint fluid dispersion and cartilage surface visibility improved after traction in nearly all joints (p < 0.05) in all patients and more so in the arthographic than in the non-arthrography group. CONCLUSION: Traction did significantly improve cartilage surface visibility for standard MRI of the wrist although the effect was not as great as that seen with MR arthography or MR arthrography with traction. Advances in knowledge: This is the first study to show the beneficial effect of traction during standard non-arthrography MRI of the wrist and compare the effect of traction between non-arthrographic and arthrographic MRI of the wrist.

Intrinsic carpal ligaments on MR and multidetector CT arthrography: comparison of axial and axial oblique planes.

PURPOSE: To compare axial and oblique axial planes on MR arthrography (MRA) and multidetector CT arthrography (CTA) to evaluate dorsal and volar parts of scapholunate (SLIL) and lunotriquetral interosseous (LTIL) ligaments. METHODS: Nine cadaveric wrists of five male subjects were studied. The visibility of dorsal and volar parts of the SLIL and LTIL was graded semi-quantitatively (good, intermediate, poor) on MRA and CTA. The presence of a ligament tear was determined on arthrosocopy and sensitivity, specificity and accuracy of tear detection were calculated. RESULTS: Oblique axial imaging was particularly useful for delineating dorsal and volar parts of the LTIL on MRA with overall 'good' visibility increased from 11 % to 78 %. The accuracy of MRA and CTA in revealing SLIL and LTIL tear was higher using the oblique axial plane. The overall accuracy for detecting SLIL tear on CTA improved from 94 % to 100 % and from 89 % to 94 % on MRA; the overall accuracy of detecting LTIL tear on CTA improved from 89 % to 100 % and from 72 % to 89 % on MRA CONCLUSION: Oblique axial imaging during CT and MR arthrography improves detection of tears in the dorsal and volar parts of both SLIL and LTIL. KEY POINTS: • Oblique axial imaging improves SLIL and LTIL visibility and tear detection. • This improvement is greater for the LTIL than for the SLIL ligament. • Overall, CT arthrography performed better than MR arthrography.

Ultrasound-guided synovial Tru-cut biopsy: indications, technique, and outcome in 111 cases.

OBJECTIVE: To investigate the diagnostic performance of ultrasound-guided synovial biopsy. METHODS: Clinical notes, pathology and microbiology reports, ultrasound and other imaging studies of 100 patients who underwent 111 ultrasound-guided synovial biopsies were reviewed. Biopsies were compared with the final clinical diagnosis established after synovectomy (n = 43) or clinical/imaging follow-up (n = 57) (mean 30 months). RESULTS: Other than a single vasovagal episode, no complication of synovial biopsy was encountered. One hundred and seven (96 %) of the 111 biopsies yielded synovium histologically. Pathology ± microbiology findings for these 107 conclusive biopsies comprised synovial tumour (n = 30, 28 %), synovial infection (n = 18, 17 %), synovial inflammation (n = 45, 42 %), including gouty arthritis (n = 3), and no abnormality (n = 14, 13 %). The accuracy, sensitivity, and specificity of synovial biopsy was 99 %, 97 %, and 100 % for synovial tumour; 100 %, 100 %, and 100 % for native joint infection; and 78 %, 45 %, and 100 % for prosthetic joint infection. False-negative synovial biopsy did not seem to be related to antibiotic therapy. CONCLUSION: Ultrasound-guided Tru-cut synovial biopsy is a safe and reliable technique with a high diagnostic yield for diagnosing synovial tumour and also, most likely, for joint infection. Regarding joint infection, synovial biopsy of native joints seems to have a higher diagnostic yield than that for infected prosthetic joints. KEY POINTS: • Ultrasound-guided Tru-cut synovial biopsy has high accuracy (99 %) for diagnosing synovial tumour. • It has good accuracy, sensitivity, and high specificity for diagnosis of joint infection. • Synovial biopsy of native joints works better than biopsy of prosthetic joints. • A negative synovial biopsy culture from a native joint largely excludes septic arthritis. • Ultrasound-guided Tru-cut synovial biopsy is a safe and well-tolerated procedure.

Elbow MR arthrography with traction.

OBJECTIVE: To assess the effect of axial traction during MR arthrography (MRA) of the elbow joint on joint space widening, contrast dispersion between opposing cartilage surfaces and cartilage surface visibility. METHODS: 11 patients with elbow MRA with and without axial traction were prospectively studied. Two radiologists independently measured the elbow joint space width and semi-quantitatively graded contrast material dispersion between the opposing cartilage surfaces as well as the articular cartilage surface visibility before and after traction. The detection and visibility of articular cartilage defects were also compared before and after traction. Patients were instructed to report on pain or any other symptoms during elbow traction. RESULTS: No patient reported discomfort, pain or any other symptoms related to traction on immediate and intermediate-term follow-up. Joint space width increased, more at the radiocapitellar joint space (Δ = 0.63 mm, p = 0.005) than at the ulnotrochlear joint space (Δ = 0.17 mm, p = 0.012), with contrast dispersion into the radiocapitellar joint and cartilage visibility of the radiocapitellar joint space significantly improving after traction (all p < 0.05). All of these parameters also improved at the ulnotrochlear joint, although this did not reach statistical significance. Traction improved the visibility of cartilage defects. CONCLUSION: This is the first study to evaluate the effect of traction on MRA of the elbow joint. This technique is safe and technically feasible. Traction MRA improves the cartilage surface visibility and cartilage defect visibility. ADVANCES IN KNOWLEDGE: This technique is safe and technically feasible. Traction MRA improves cartilage surface visibility and cartilage defect visibility.

Multi-disciplinary Orthopaedics Rehabilitation Empowerment (MORE) program: A new standard of care for injured workers in Hong Kong.

BACKGROUND: The objective of this study is to evaluate the effects of the Multi-disciplinary Orthopaedics Rehabilitation Empowerment (MORE) Program on reducing chronic disability among injured workers and improving efficiency of work rehabilitation process. METHODS: A cohort of patients with workplace injuries in the lower back were recruited from orthopaedics clinics and assigned to either MORE group (n= 139) or control group (n= 106). Patients in MORE group received an early MRI screening and a coordinated multi-disciplinary management, while patients in the control group received conventional care. Outcome variables are time to return-to-work (RTW) from date of injury, waiting time for MRI screening and time to medical assessment board (MAB). RESULTS: Patients in the MORE Program had significantly shorter duration for RTW (MORE: 6.1 months, CONTROL: 12.8 months, p< 0.01), and more RTW cases (n= 64, 46.0%) compared to CONTROL group (n= 29, 27.4%). The MORE group also had much shorter waiting time for MRI scans (91.85 vs. 309.2 days, p< 0.001) and MAB referral after MRI scans (97.2 vs. 178.9 days, p= 0.001) compared to CONTROL group. CONCLUSIONS: The MORE Program which emphasizes early intervention and early MRI screening, is shown to be effective in shortening sick leave and improving RTW outcomes of injured workers.

Wrist Traction During MR Arthrography Improves Detection of Triangular Fibrocartilage Complex and Intrinsic Ligament Tears and Visibility of Articular Cartilage.

OBJECTIVE: The purpose of this study was to assess the effects of traction during MR arthrography of the wrist on joint space widening, cartilage visibility, and detection of tears of the triangular fibrocartilage complex (TFCC) and intrinsic ligaments. SUBJECTS AND METHODS: A prospective study included 40 wrists in 39 patients (25 men, 14 women; mean age, 35 years). MR arthrography was performed with a 3-T MRI system with and without axial traction. Two radiologists independently measured wrist and carpal joint space widths and semiquantitatively graded articular cartilage visibility. Using conventional arthrography as the reference standard and working in consensus, they assessed for the presence of tears of the TFCC, lunotriquetral ligament (LTL), and scapholunate ligament (SLL). Visibility of a tear before traction was compared with visibility after traction. RESULTS: With traction, all joint spaces in the wrist and carpus were significantly widened (change, 0.15-1.01 mm; all p < 0.006). Subjective cartilage visibility of all joint spaces improved after traction (all p ≤ 0.048) except for that of the radioscaphoid space, which was well visualized even before traction. Conventional arthrography depicted 24 TFCC tears, seven LTL tears, and three SLL tears. The accuracy of tear detection improved after traction for the TFCC (98% after traction vs 83% before traction), the LTL (100% vs 88%), and the SLL (100% vs 95%). Tear visibility improved after traction for 54% of TFCC tears, 71% of LTL tears, and 66% of SLL tears. CONCLUSION: Wrist MR arthrography with axial traction significantly improved the visibility of articular cartilage and the detection and visibility of tears of the TFCC and intrinsic ligaments. The results favor more widespread use of traction during MR arthrography of the wrist.

Effect of upright position on tonsillar level in adolescent idiopathic scoliosis.

PURPOSE: The aim of this study was to investigate the effect of an upright position on cerebellar tonsillar level in patients with adolescent idiopathic scoliosis (AIS). METHODS: Twenty-five patients with clinically diagnosed AIS and 18 normal controls were examined in both supine and upright positions using 0.25T MRI. The position of the inferior cerebellar tonsil tip relative to a reference line connecting the basion to the opisthion (BO line) was measured in millimetres. RESULTS: None of the 18 normal control subjects had cerebellar tonsillar descent below the BO line in either supine or the upright position. Forty-eight percent of AIS patients had tonsillar descent in the upright position, compared to 28 % in the supine position. In the upright position, cerebellar tonsillar position was lower in AIS patients than in normal subjects (mean -0.7 ± 1.5 vs. +2.1 ± 1.7, p < 0.00001). AIS patients also had a large degree of tonsillar excursion between upright and supine positions compared to normal subjects (mean -1.9 ± 2.3 vs. -0.1 ± 0.2, p < 0.00001). CONCLUSIONS: When considering the theoretical likelihood that a low tonsillar position may affect spinal cord function, one should bear in mind that tonsillar descent in AIS is significantly greater in the upright position. KEY POINTS: • AIS patients exhibited greater cerebellar tonsillar descent in upright than supine position. • Cerebellar tonsillar position was lower in AIS patients than normal subjects. • AIS patients exhibited greater tonsillar excursion between supine and upright positions.

Atypical intracranial epidermoid cysts: rare anomalies with unique radiological features.

Epidermoid cysts are benign slow growing extra-axial tumours that insinuate between brain structures, while their occurrences in intra-axial or intradiploic locations are exceptionally rare. We present the clinical, imaging, and pathological findings in two patients with atypical epidermoid cysts. CT and MRI findings for the first case revealed an intraparenchymal epidermoid cyst that demonstrated no restricted diffusion. The second case demonstrated an aggressive epidermoid cyst that invaded into the intradiploic spaces, transverse sinus, and the calvarium. The timing of ectodermal tissue sequestration during fetal development may account for the occurrence of atypical epidermoid cysts.

Dynamic contrast-enhanced imaging of the wrist in rheumatoid arthritis: dedicated low-field (0.25-T) versus high-field (3.0-T) MRI.

OBJECTIVE: To compare the assessment of wrist synovitis severity, synovial volume and synovial perfusion parameters on a dedicated low-field (0.25-T) to that of a high-field (3-T) whole-body MR system in patients with rheumatoid arthritis (RA). METHODS: Twenty-one patients (mean age 50.0 ± 9.8 years) with active RA were recruited prospectively. Dynamic contrast-enhanced MRI examination of the most severely affected wrist was performed at both 0.25 T and 3 T. Three MRI-derived parameters, synovitis severity (RAMRIS grade), synovial volume (ml(3)) and synovial perfusion indices (maximum enhancement and enhancement slope), were compared. RESULTS: Comparing 0.25- and 3-T MRI, there was excellent agreement for semiquantitative assessment (r: 0.80, p < 0.00001) of synovitis (RAMRIS) as well as quantitative assessment (r: 0.94, p < 0.00001) of synovial volume. Good agreement for synovial Emax (r: 0.6, p = 0.002) and fair agreement (r: 0.5, p = 0.02) for synovial Eslope was found. CONCLUSIONS: Imaging of the RA wrist at 0.25 T yields excellent correlation with 3 T with regard to the synovitis activity score (RAMRIS) and synovial volume measurement. Fair to good correlation between low- (0.25-T) and high-field (3-T) MR systems was found for perfusion parameters, being better for Emax than for Eslope.