Arterial spin labeled perfusion MRI for the assessment of radiation-treated meningiomas.

Purpose: Conventional contrast-enhanced MRI is currently the primary imaging technique used to evaluate radiation treatment response in meningiomas. However, newer perfusion-weighted MRI techniques, such as 3D pseudocontinuous arterial spin labeling (3D pCASL) MRI, capture physiologic information beyond the structural information provided by conventional MRI and may provide additional complementary treatment response information. The purpose of this study is to assess 3D pCASL for the evaluation of radiation-treated meningiomas. Methods: Twenty patients with meningioma treated with surgical resection followed by radiation, or by radiation alone, were included in this retrospective single-institution study. Patients were evaluated with 3D pCASL and conventional contrast-enhanced MRI before and after radiation (median follow up 6.5 months). Maximum pre- and post-radiation ASL normalized cerebral blood flow (ASL-nCBF) was measured within each meningioma and radiation-treated meningioma (or residual resected and radiated meningioma), and the contrast-enhancing area was measured for each meningioma. Wilcoxon signed-rank tests were used to compare pre- and post-radiation ASL-nCBF and pre- and post-radiation area. Results: All treated meningiomas demonstrated decreased ASL-nCBF following radiation (p < 0.001). Meningioma contrast-enhancing area also decreased after radiation (p = 0.008) but only for approximately half of the meningiomas (9), while half (10) remained stable. A larger effect size (Wilcoxon signed-rank effect size) was seen for ASL-nCBF measurements (r = 0.877) compared to contrast-enhanced area measurements (r = 0.597). Conclusions: ASL perfusion may provide complementary treatment response information in radiation-treated meningiomas. This complementary information could aid clinical decision-making and provide an additional endpoint for clinical trials.

Dispersed Bone Spicules as a Cause of Postoperative Headache after Retrosigmoid Vestibular Schwannoma Surgery: A Myth?

Objectives Dispersion of bone dust in the posterior fossa during retrosigmoid craniectomy for vestibular schwannoma (VS) resection could be a source of meningeal irritation and lead to development of persistent postoperative headaches (POH). We aim to determine risk factors, including whether the presence of bone spicules that influence POH after retrosigmoid VS resection. Design Present study is a retrospective case series. Setting The study was conducted at a tertiary skull-base referral center. Participants Adult patients undergoing VS resection via a retrosigmoid approach between November 2017 and February 2020 were included for this study. Main Outcome Measures Development of POH lasting ≥ 3 months is the primary outcome of this study. Results Of 64 patients undergoing surgery, 49 had complete data (mean age, 49 years; 53% female). Mean follow-up time was 2.4 years. At latest follow up, 16 (33%) had no headaches, 14 (29%) experienced headaches lasting <3 months, 19 (39%) reported POH lasting ≥3 months. Twenty-seven (55%) patients had posterior fossa bone spicules detectable on postoperative computed tomography (CT). Age, gender, body mass index, length of stay, tumor diameter, size of craniectomy, the presence of bone spicules, or the amount of posterior petrous temporal bone removed from drilling did not differ significantly between patients with POH and those without. On multivariate logistic regression, patients with POH were less likely to have preoperative brainstem compression by the tumor (odds ratio [OR] = 0.21, p = 0.028) and more likely to have higher opioid requirements during hospitalization (OR = 1.023, p = 0.045). Conclusion The presence of bone spicules in the posterior fossa on postoperative CT did not contribute to headaches following retrosigmoid craniectomy approach for VS resection.

Starting a Free Ultrasound Clinic for the Underserved: Considerations and Overcoming Challenges.

Many radiologists are interested in providing affordable care to underserved populations but are unsure how to accomplish it. We present a model for providing imaging services to the underserved with an emphasis on the challenges we encountered and strategies we used to overcome them. In partnership with our medical school's student-run free clinic, we developed a community-based ultrasound service that provides diagnostic ultrasound examinations to an uninsured urban population to address the need of timely access to care and integrated follow-up care. Image storage and reporting were fully integrated with our existing imaging informatics and electronic medical record systems. Radiology residents play a central role in the operation of the service while gaining hands-on ultrasound experience, in partnership with volunteer sonographers, radiology attendings, and medical students.

Exposure to low concentrations of pesticide stimulates ecological functioning in the dung beetle Onthophagus nuchicornis.

Body-size is an important trait for predicting how species contribute to ecosystem functions and respond to environmental stress. Using the dung beetle Onthophagus nuchicornis (Coleoptera: Scarabaeidae), we explored how variation in body-size affected ecosystem functioning (dung burial) and sensitivity to an environmental stressor (exposure to the veterinary anthelmintic ivermectin). We found that large beetles buried nearly 1.5-fold more dung than small beetles, but that mortality from exposure to a range of concentrations of ivermectin did not differ between large and small beetles. Unexpectedly, we found that exposure to low concentrations of ivermectin (0.01⁠-1 mg ivermectin per kg dung) stimulated dung burial in both small and large beetles. Our results provide evidence of ecological functioning hormesis stemming from exposure to low amounts of a chemical stressor that causes mortality at high doses.

Differentiation of progressive disease from pseudoprogression using 3D PCASL and DSC perfusion MRI in patients with glioblastoma.

PURPOSE: To use 3D pseudocontinuous arterial spin labeling (3D PCASL) and dynamic susceptibility contrast-enhanced (DSC) perfusion MRI to differentiate progressive disease from pseudoprogression in patients with glioblastoma (GBM). METHODS: Thirty-two patients with GBM who developed progressively enhancing lesions within the radiation field following resection and chemoradiation were included in this retrospective, single-institution study. The updated modified RANO criteria were used to establish progressive disease or pseudoprogression. Following 3D PCASL and DSC MR imaging, perfusion parameter estimates of cerebral blood flow (ASL-nCBF and DSC-nrCBF) and cerebral blood volume (DSC-nrCBV) were calculated. Additionally, contrast enhanced volumes were measured. Mann-Whitney U tests were used to compare groups. Linear discriminant analysis (LDA) and area under receiver operator characteristic curve (AUC) analyses were used to evaluate performance of each perfusion parameter and to determine optimal cut-off points. RESULTS: All perfusion parameter measurements were higher in patients with progressive disease (mean, 95% CI ASL-nCBF 2.48, [2.03, 2.93]; DSC-nrCBF = 2.27, [1.85, 2.69]; DSC-nrCBV = 3.51, [2.37, 4.66]) compared to pseudoprogression (mean, 95% CI ASL-nCBF 0.99, [0.47, 1.52]; DSC-nrCBF = 1.05, [0.36, 1.74]; DSC-nCBV = 1.19, [0.34, 2.05]), and findings were significant at the p < 0.0125 level (p = 0.001, 0.003, 0.002; effect size: Cohen's d = 1.48, 1.27, and 0.92). Contrast enhanced volumes were not significantly different between groups (p > 0.447). All perfusion parameters demonstrated high AUC (0.954 for ASL-nCBF, 0.867 for DSC-nrCBF, and 0.891 for DSC-nrCBV), however, ASL-nCBF demonstrated the highest AUC and misclassified the fewest cases (N = 6). Lesions correctly classified by ASL but misclassified by DSC were located along the skull base or adjacent to large resection cavities with residual blood products, at areas of increased susceptibility. CONCLUSION: Both 3D PCASL and DSC perfusion MRI techniques have nearly equivalent performance for the differentiation of progressive disease from pseudoprogression in patients with GBM. However, 3D PCASL is less sensitive to susceptibility artifact and may allow for improved classification in select cases.

Radiographic appearance of the distal clavicle in relation to the acromion after acromioclavicular joint reconstruction using a braided polyester mesh.

ACJ stabilization using a braided polyester mesh has become popular in ACJ injuries. However, concerns have been raised about excessive anterior clavicle displacement. The purpose of this study was to report radiographic position of the distal clavicle in relation to the acromion after ACJ reconstruction using this device immediately postoperative and after 6 months follow-up compared with a healthy control group. Thirty-eight patients with ACJ instability treated with a braided polyester mesh were compared within group (pre-/postoperatively) and between groups (with age/sex matched controls). Biplane radiographic measurements by 2 observers were made preoperatively, immediate postoperatively and at 6 months follow-up. Inter-observer reliability was assessed and clinical outcome scores were recorded. ACJ stabilization significantly reduced vertical displacement immediately postoperatively (13.8 ±â€¯4.2 to 3.5 ±â€¯5.5 mm; p < 0.0001) towards controls (1.7 ±â€¯2.3 mm,p < 0.0873). Slight further superior displacement (4.4 mm) occurred at 6 months follow-up compared to immediately postoperative (p = 0.0029) and 6.2 mm more than mean controls (p < 0.0001). In the axial plane, significant early reduction of posterior displacement was achieved (10.3 ±â€¯8.0 to 1.1 ±â€¯5.1 mm,p = 0.0240) and the clavicle settled back to a more posterior position at 4.5 ±â€¯6.7  mm at 6 months post-surgery (p = 0.3062). At both time points, posterior displacement was comparable with the controls (3.4 ±â€¯3.0 mm,p = 0.4371 postoperative, p = 0.563 at 6 months follow-up). Excessive anterior displacement has been observed in 2 of the 5 available axial radiographs early postoperative and in 4 of 14 available axial radiographs at 6 months. Constant, Oxford Shoulder and Nottingham Clavicle scores significantly improved (25 ±â€¯12 to 43 ±â€¯7:p < 0.0001, 46 ±â€¯27 to 80 ±â€¯19:p = 0.0038, 53 ±â€¯14 to 80 ±â€¯17:p < 0.0001). ACJ stabilization using a braided polyester device in ACJ instability is effective at reducing both superior and posterior clavicle displacement with excellent clinical outcome. Overcorrection in the axial plane seems to occur, however this is of no clinical and radiographic significance. Posterior displacement is significantly reduced towards control values at 6 months follow-up.

Melorheostosis with an associated para-articular enhancing soft tissue mass.

Melorheostosis is a rare non-hereditary sclerosing bone dysplasia which predominantly affects the appendicular skeleton. Although melorheostosis is typically recognized as an osseous lesion, associated soft-tissue components have been reported. Advanced imaging with MRI may allow for more complete evaluation of these soft tissue components; however, there is little information regarding their MRI characteristics which may lead to confusion with malignant processes. We present a case of melorheostosis in a 32-year-old woman with an associated paraarticular enhancing soft tissue mass and emphasize discriminating this from soft tissue sarcoma.

Arthroscopic knotless anterior labral stabilization using labral tape and wide awake anaesthesia-short term results.

BACKGROUND: The shoulder is the least constrained of all joints of the body and is more susceptible to injury including dislocation. The rate of recurrent instability following primary stabilization procedure at 10 years of follow-up ranged from 3.4 to 20%. There is a lack of evidence in the literature regarding use of labral tape and anchors for anterior stabilization despite the growing market for this product. We describe the outcomes of 67 patients who underwent knotless arthroscopic anterior stabilisation under awake anaesthesia using 1.5 mm LabralTape with 2.9 mm Pushlock anchors for primary anterior instability by a single surgeon. METHODS: This was a retrospective analysis of prospectively collected outcome data for adult patients undergoing anterior stabilisation for primary traumatic anterior shoulder instability between 2013 and 2016 at two centres. Patients with > 25% glenoid bone loss, engaging Hill Sach's, and multidirectional instability were excluded. All cases underwent surgery using awake anaesthetic technique. The surgical technique and post-operative physiotherapy was standardized. Outcomes were measured at 6 months and 12 months. RESULTS: Of the 74 patients in our study, 7 were lost to follow up. Outcomes were measured using the Oxford Instability Shoulder Score (OISS) and clinical assessment including the range of motion. The OISS showed statistically significant improvement from a mean score and standard deviation (SD) of 24.72 ± 2.8 pre-surgery to 43.09 ± 3.5 after the procedure at 12 months with good to excellent outcomes in 66 cases (98.5%). The mean abduction was 134.2 ± 6.32 and external rotation was 72.55 ± 5.42 at 60-90 position at 12 months. We report no failures due to knot slippage or anchor pull-out. CONCLUSION: Our case series using the above technique has distinct advantages of combining a small non-absorbable implant with flat, braided, and high-strength polyethylene tape. This technique demonstrates superior medium term results to conventional suture knot techniques for labral stabilization thereby validating its use.

Cross-sectional correlation between hepatic R2* and proton density fat fraction (PDFF) in children with hepatic steatosis.

PURPOSE: To determine the relationship between hepatic proton density fat fraction (PDFF) and R2* in vivo. MATERIALS AND METHODS: In this Health Insurance Portability and Accountability Act (HIPAA)-compliant, Institutional Review Board (IRB)-approved, cross-sectional study, we conducted a secondary analysis of 3T magnetic resonance imaging (MRI) exams performed as part of prospective research studies in children in whom conditions associated with iron overload were excluded clinically. Each exam included low-flip-angle, multiecho magnitude (-M) and complex (-C) based chemical-shift-encoded MRI techniques with spectral modeling of fat to generate hepatic PDFF and R2* parametric maps. For each technique and each patient, regions of interest were placed on the maps in each of the nine Couinaud segments, and composite whole-liver PDFF and R2* values were calculated. Pearson's correlation coefficients between PDFF and R2* were computed for each MRI technique. Correlations were compared using Steiger's test. RESULTS: In all, 184 children (123 boys, 61 girls) were included in this analysis. PDFF estimated by MRI-M and MRI-C ranged from 1.1-35.4% (9.44 ± 8.76) and 2.1-38.1% (10.1 ± 8.7), respectively. R2* estimated by MRI-M and MRI-C ranged from 32.6-78.7 s-1 (48.4 ± 9.8) and 27.2-71.5 s-1 (42.2 ± 8.6), respectively. There were strong and significant correlations between hepatic PDFF and R2* values estimated by MRI-M (r = 0.874; P < 0.0001) and MRI-C (r = 0.853; P < 0.0001). The correlation coefficients (0.874 vs. 0.853) were not significantly different (P = 0.15). CONCLUSION: Hepatic PDFF and R2* are strongly correlated with each other in vivo. This relationship was observed using two different MRI techniques. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:418-424.

Quantifying immediate and delayed effects of anthelmintic exposure on ecosystem functioning supported by a common dung beetle species.

Dung beetles (Coleoptera: Scarabaeoidea) support numerous ecosystem functions in livestock-grazed pastures. Exposure to veterinary anthelmintic residues in livestock dung can have lethal and sublethal effects on dung beetles, and can reduce rates of dung removal, but the immediate and longer-term consequences for other dung beetle mediated functions have rarely been studied. We investigated the consequences of anthelmintic exposure on survival of the dung beetle Aphodius fossor and its delivery of four ecosystems functions that underpin pasture production: dung removal, soil fauna feeding activity, primary productivity, and reduction of soil compaction. We tested whether anthelmintic exposure had immediate or delayed effects on these functions individually and simultaneously (i.e., ecosystem multifunctionality). We found no evidence that ivermectin residues had a lethal effect on adult beetles. For dung removal, we found a significant interaction between the timing of exposure and functioning: while dung removal was impaired by concurrent exposure to high levels of ivermectin, functioning was unaffected when beetles that had been exposed previously to the same concentration of anthelmintic later interacted with untreated dung. Other ecosystem functions were not affected significantly by anthelmintic exposure, and there was no evidence to suggest any persistent impact of anthelmintic exposure on ecosystem multifunctionality. While anthelmintic residues remain a significant threat to dung beetle populations, for adult beetles, we found no evidence that residues have detrimental consequences for ecosystem functioning beyond the immediate point of exposure.

A validation of the Nottingham Clavicle Score: a clavicle, acromioclavicular joint and sternoclavicular joint-specific patient-reported outcome measure.

BACKGROUND: Patients with acromioclavicular joint (ACJ) and sternoclavicular joint (SCJ) injuries and with clavicle fractures are typically younger and more active than those with other shoulder pathologies. We developed the Nottingham Clavicle Score (NCS) specifically for this group of patients to improve sensitivity for assessing the outcomes of treatment of these conditions compared with the more commonly used Constant Score (CS) and Oxford Shoulder Score (OSS). MATERIALS AND METHODS: This was a cohort study in which the preoperative and 6-month postoperative NCS evaluations of outcome in 90 patients were compared with the CS, OSS, Imatani Score (IS), and the EQ-5D scores. Reliability was assessed using the Cronbach α. Reproducibility of the NCS was assessed using the test/retest method. Effect sizes were calculated for each score to assess sensitivity to change. Validity was examined by correlations between the NCS and the CS, OSS, IS, and EQ-5D scores obtained preoperatively and postoperatively. RESULTS: Significant correlations were demonstrated preoperatively with the OSS (P = .025) and all subcategories of the EQ-5D (P < .05) and postoperatively with the OSS (P < .001), CS (P = .008), IS (P < .001), and all subcategories of EQ-5D (P < .02). The NCS had the largest effect size (1.92) of the compared scores. Internal consistency was excellent (Cronbach α = 0.87). CONCLUSION: The NCS has been proven to be a valid, reliable and sensitive outcome measure that accurately measures the level of function and disability in the ACJ, SCJ and clavicle after traumatic injury and in degenerative disease.

Repeatability and reproducibility of 2D and 3D hepatic MR elastography with rigid and flexible drivers at end-expiration and end-inspiration in healthy volunteers.

PURPOSE: To evaluate the repeatability and reproducibility of 2D and 3D hepatic MRE with rigid and flexible drivers at end-expiration and end-inspiration in healthy volunteers. MATERIALS AND METHODS: Nine healthy volunteers underwent two same-day MRE exams separated by a 5- to 10-min break. In each exam, 2D and 3D MRE scans were performed, each under four conditions (2 driver types [rigid, flexible] × 2 breath-hold phases [end-expiration, end-inspiration]). Repeatability (measurements under identical conditions) and reproducibility (measurements under different conditions) were analyzed by calculating bias, limit of agreement, repeatability coefficient (RC), reproducibility coefficient (RDC), intraclass correlation coefficient (ICC), and concordance correlation coefficient (CCC), as appropriate. RESULTS: For 2D MRE, RCs and ICCs range between 0.29-0.49 and 0.71-0.91, respectively. For 3D MRE, RCs and ICCs range between 0.16-0.26 and 0.84-0.96, respectively. Stiffness values were biased by breath-hold phase, being higher at end-inspiration than end-expiration, and the differences were significant for 3D MRE (p < 0.01). No bias was found between driver types. Inspiration vs. expiration RDCs and CCCs ranged between 0.30-0.54 and 0.61-0.72, respectively. Rigid vs. flexible driver RDCs and CCCs ranged between 0.10-0.44 and 0.79-0.94, respectively. CONCLUSION: This preliminary study suggests that 2D MRE and 3D MRE under most conditions potentially have good repeatability. Our result also points to the possibility that stiffness measured with the rigid and flexible drivers is reproducible. Reproducibility between breath-hold phases was modest, suggesting breath-hold phase might be a confounding factor in MRE-based stiffness measurement. However, larger studies are required to validate these preliminary results.

Liver histology and diffusion-weighted MRI in children with nonalcoholic fatty liver disease: A MAGNET study.

PURPOSE: To determine potential associations between histologic features of pediatric nonalcoholic fatty liver disease (NAFLD) and estimated quantitative magnetic resonance diffusion-weighted imaging (DWI) parameters. MATERIALS AND METHODS: This prospective, cross-sectional study was performed as part of the Magnetic Resonance Assessment Guiding NAFLD Evaluation and Treatment (MAGNET) ancillary study to the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN). Sixty-four children underwent a 3T DWI scan (b-values: 0, 100, and 500 s/mm2 ) within 180 days of a clinical liver biopsy of the right hepatic lobe. Three parameters were estimated in the right hepatic lobe: apparent diffusion coefficient (ADC), diffusivity (D), and perfusion fraction (F); the first assuming exponential decay and the latter two assuming biexponential intravoxel incoherent motion. Grading and staging of liver histology were done using the NASH CRN scoring system. Associations between histologic scores and DWI-estimated parameters were tested using multivariate linear regression. RESULTS: Estimated means ± standard deviations were: ADC: 1.3 (0.94-1.8) × 10-3 mm2 /s; D: 0.82 (0.56-1.0) × 10-3 mm2 /s; and F: 17 (6.0-28)%. Multivariate analyses showed ADC and D decreased with steatosis and F decreased with fibrosis (P < 0.05). Associations between DWI-estimated parameters and other histologic features were not significant: ADC: fibrosis (P = 0.12), lobular inflammation (P = 0.20), portal inflammation (P = 0.27), hepatocellular inflammation (P = 0.29), NASH (P = 0.30); D: fibrosis (P = 0.34), lobular inflammation (P = 0.84), portal inflammation (P = 0.76), hepatocellular inflammation (P = 0.38), NASH (P = 0.81); F: steatosis (P = 0.57), lobular inflammation (P = 0.22), portal inflammation (P = 0.42), hepatocellular inflammation (P = 0.59), NASH (P = 0.07). CONCLUSION: In children with NAFLD, steatosis and fibrosis have independent effects on DWI-estimated parameters ADC, D, and F. Further research is needed to determine the underlying mechanisms and clinical implications of these effects. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1149-1158.

Agreement between region-of-interest- and parametric map-based hepatic proton density fat fraction estimation in adults with chronic liver disease.

PURPOSE: To compare agreement between region-of-interest (ROI)- and parametric map-based methods of hepatic proton density fat fraction (PDFF) estimation in adults with known or suspected hepatic steatosis secondary to chronic liver disease over a range of imaging and analysis conditions. MATERIALS AND METHODS: In this IRB approved HIPAA compliant prospective single-site study, 31 adults with chronic liver disease undergoing clinical gadoxetic acid-enhanced liver magnetic resonance imaging at 3 T were recruited. Multi-echo gradient-echo imaging at flip angles of 10° and 50° was performed before and after administration of gadoxetic acid. Six echoes were acquired at successive nominally out-of-phase and in-phase echo times. PDFF was estimated with a nonlinear fitting algorithm using the first two, three, four, five, and (all) six echoes. Hence, 20 different imaging and analysis conditions were used (pre/post contrast x low/high flip angle x 2/3/4/5/6 echoes). For each condition, PDFF estimation was done in corresponding liver locations using two methods: a region-of-interest (ROI)-based method in which mean signal intensity values within ROIs were run through the fitting algorithm, and a parametric map-based method in which individual signal intensities were run through the fitting algorithm pixel by pixel. Agreement between ROI- and map-based PDFF estimation was assessed by Bland-Altman and intraclass correlation (ICC) analysis. RESULTS: Depending on the condition and method, PDFF ranged from -2.52% to 45.57%. Over all conditions, mean differences between ROI- and map-based PDFF estimates ranged from 0.04% to 0.24%, with all ICCs ≥0.999. CONCLUSION: Agreement between ROI- and parametric map-based PDFF estimation is excellent over a wide range of imaging and analysis conditions.