Variability of scan quality and perfusion density in longitudinal optical coherence tomography angiography imaging.

BACKGROUND/AIMS: Optical coherence tomography angiography (OCT-A) images are subject to variability, but the extent to which learning impacts OCT-A measurements is unknown. We determined whether there is a learning effect in glaucoma patients and healthy controls imaged with OCT-A. METHODS: Ninety-one open-angle glaucoma patients and 54 healthy controls were imaged every 4 months over a period of approximately 1 year in this longitudinal cohort study. We analysed 15°×15° scans, centred on the fovea, in one eye of each participant. Two-dimensional projection images for the superficial, intermediate and deep vascular plexuses were exported and binarised after which perfusion density was calculated. Linear mixed-effects models were used to investigate the association between perfusion density and follow-up time. RESULTS: The mean (SD) age of glaucoma patients and healthy controls was 67.3 (8.1) years and 62.1 (9.0) years, respectively. There was a significant correlation between perfusion density and scan quality in both glaucoma patients (r=0.50 (95% CI 0.42 to 0.58); p<0.05) and healthy controls (r=0.41 (95% CI 0.29 to 0.52); p<0.05). An increase in perfusion density occurred over time and persisted, even after adjustment for scan quality (1.75% per year (95% CI 1.14 to 2.37), p<0.01). CONCLUSIONS: Perfusion density measurements are subject to increasing experience of either the operator or participant, or a combination of both. These findings have implications for the interpretation of longitudinal measurements with OCT-A.

Short-term structural and functional changes after airway clearance therapy in cystic fibrosis.

BACKGROUND: Airway clearance therapy (ACT) with a high-frequency chest wall oscillation (HFCWO) vest is a common but time-consuming treatment. Its benefit to quality of life for cystic fibrosis (CF) patients is well established but has been questioned recently as new highly-effective modulator therapies begin to change the treatment landscape. 129Xe ventilation MRI has been shown to be very sensitive to lung obstruction in mild CF disease, making it an ideal tool to identify and quantify subtle, regional changes. METHODS: 20 CF patients (ages 20.7 ± 5.1 years) refrained from performing ACT before arriving for a single-day visit. Multiple-breath washout (MBW), spirometry, Xe MRI, and ultrashort echo-time (UTE) MRI were obtained twice-before and after patients performed ACT using their prescribed HFCWO vests (average 4.7 ± 0.5 h). UTE MRIs were scored for structural abnormalities, and standard functional metrics were obtained from MBW, spirometry, and Xe MRI-FEV1,pp, LCI2.5, and VDPN4, respectively. RESULTS: Spirometry and Xe MRI detected significant improvements in lung function post-ACT. 15/20 patients showed improvements from a baseline median of 92% FEV1,pp. Similarly, 16/20 patients showed improvements in Xe MRI from a baseline median of 15.2% VDPN4. Average individual changes were +2.6% in FEV1,pp and -1.3% in VDPN4, but without spatial correlations to easily-identifiable causative structural defects (e.g. mucus plugs or bronchiectasis) on UTE MRI. CONCLUSIONS: Lung function improved after a single instance of HFCWO-vest ACT and was detectable by spirometry and Xe MRI. The only common structural abnormalities were mucus plugs, which corresponded to ventilation defects, but ventilation defects were often present without visible abnormalities.

Describing angular momentum conventions in circularly polarized optically pumped NMR in GaAs and CdTe.

The physical phenomena governing hyperpolarization through optical pumping of conduction electrons continue to be explored in multiple semiconductor systems. One early finding has been the asymmetry between the optically pumped nuclear magnetic resonance (OPNMR) signals when generated by different circular polarizations (i.e., light helicities). Because these resonances are asymmetric, the midpoint between the signals prepared with each of the two circular polarizations is either a positive or negative value, termed an "offset" that is representative of an optical Overhauser enhancement. Both negative offsets (in GaAs) and positive offsets (in CdTe) have been observed. The origins of these offsets in semiconductors are believed to arise from thermalized electrons; however, to the best of our knowledge, no study has systematically tested this hypothesis. To that end, we have adopted two configurations for OPNMR experiments-one in which the Poynting vector of the laser light and magnetic field are parallel, and one in which they are antiparallel, while other experimental conditions are kept the same. We find that the OPNMR signal response to a fixed helicity of light depends on the experimental configuration, and this configuration needs to be accounted for in order to properly describe the OPNMR results. Further, studying the offsets as a function of field strength shows that the optical Overhauser enhancement (the offset) increases in magnitude with field strength. Finally, by describing all angular momentum and phasing conventions unambiguously, we are able to determine that the absorptively-phased appearance of 113Cd (and 125Te) OPNMR in CdTe is a consequence of the sign of the nuclear gyromagnetic ratios for these isotopes.

Discrepancy in Loss of Macular Perfusion Density and Ganglion Cell Layer Thickness in Early Glaucoma.

PURPOSE: To identify characteristics of patients with early open-angle glaucoma exhibiting greater macular perfusion density (PD) loss compared with macular ganglion cell layer (GCL) thickness loss. DESIGN: Cross-sectional study. METHODS: Optical coherence tomography (OCT) imaging of the optic nerve head and macula was conducted in patients and healthy control subjects. Minimum rim width, retinal nerve fiber layer and GCL thickness, and PD from OCT angiography were derived. Only high-quality images were included. For direct comparison, raw PD and GCL thickness values in patients were converted to relative age-corrected loss values based on data from controls. Demographic and ocular variables related to greater PD loss compared with GCL thickness loss were identified with multivariate logistic regression. RESULTS: Data from 89 patients (median mean deviation with the 24-2 and 10-2 tests, Humphrey Field Analyzer: -1.96 dB and -1.49 dB, respectively) and 54 controls were analyzed. Sixty-three (71%) patients had relatively more GCL thickness loss, whereas 26 (29%) had relatively more PD loss. More PD loss was associated with lower OCT and OCT-angiography signal strength (odds ratio [95% confidence interval], 0.64 [0.40, 0.96] and 0.60 [0.38, 0.86], per dB, respectively), thicker retinal nerve fiber layer thickness (1.08 [1.01, 1.16] per µm), and female sex (6.57 [1.25, 48.79]). CONCLUSION: Less than one-third of patients with early glaucoma had more loss of perfusion compared with conventional structural loss in the macula. Even within a range of high-quality images, lower signal strength may be at least partially responsible for apparent perfusion loss.

Value of 10-2 Visual Field Testing in Glaucoma Patients with Early 24-2 Visual Field Loss.

PURPOSE: To determine whether the 10-2 test of the Humphrey Field Analyzer detected a higher proportion of abnormal visual fields compared with the 24-2 test in the central 10° of patients with early glaucomatous visual field damage. DESIGN: Prospective observational study. PARTICIPANTS: Patients with open-angle glaucoma and healthy control participants. METHODS: All participants underwent a 24-2 and 10-2 test. Only the 12 central test locations of the 24-2 test were included to analyze equivalent visual field areas. The performance of the 2 tests was compared across 4 pointwise criteria: total deviation (TD) and pattern deviation (PD) analyses at the 5% and 2% levels. Analyses also were conducted for 2 pairs of follow-up tests, each performed 4 months apart. MAIN OUTCOME MEASURES: (1) Area under the receiver operating characteristic curve (AUC), (2) sensitivity at identically matched specificity for the 4 criteria, (3) overlap (entire field and by quadrant) of abnormal visual fields with both tests, and (4) repeatability of the findings in 2 subsequent follow-up tests. RESULTS: One eye each of 97 glaucoma patients (median mean deviation, -2.31 dB) and 65 control participants were included in the study. The AUCs for the 24-2 and 10-2 tests were not significantly different for any of the 4 criteria and ranged from 0.88 to 0.93 and from 0.91 to 0.94, respectively. At matched specificity, the sensitivity of the 24-2 test was significantly higher for all criteria except for PD analysis at 5%. In patients with an abnormal field with either test, the overlap varied from 60% to 86% depending on the criterion, whereas by quadrant, concordance ranged from 70% to 87%. Over the follow-up, the repeatability of test results (both 24-2 and 10-2 abnormal, either abnormal, or both normal) was achieved in 55% to 70% of patients. CONCLUSIONS: In this study of glaucoma patients with early damage with the 24-2 test, there was little evidence that adding the 10-2 test revealed additional undetected defects in the central visual field. It may be more prudent to reserve 10-2 testing for following up selected patients with higher risk of central visual field progression.

Asymmetry analysis of macular optical coherence tomography angiography in patients with glaucoma and healthy subjects.

BACKGROUND/AIMS: Quantitative analysis of optical coherence tomography angiography (OCT-A) images requires a reproducible approach that accounts for sectoral loss. The objective of this study was to determine whether an index that accounts for both global (perfusion density, PD) and asymmetric loss of perfusion, rather than PD alone, more reliably measures loss of perfusion in patients with glaucoma. METHODS: We analysed macular OCT-A scans of 95 glaucoma patients and 59 control subjects. Two-dimensional projection images corresponding to the superficial vascular plexus were exported and analyses performed to calculate global PD and image asymmetry. An unsigned perfusion asymmetry index (PAI) that included PD and asymmetry (with 1:1 wt) was calculated. Perfusion density and PAI were compared with 10-2 visual field mean deviation and ganglion cell layer (GCL) thickness. RESULTS: Median (IQR) visual field mean deviation was -1.73 (-3.76, 0.30) dB for the glaucoma group and 0.67 (0.16, 1.18) dB for the control group. The strength of the correlation with mean deviation was stronger for PAI (r=0.47), compared with PD (r=0.35), whereas with GCL thickness they were comparable (r=0.45 and 0.43, respectively). Compared with controls, mean PD was 12% lower in patients with glaucoma (0.27 vs 0.30), while PAI was 17% lower (0.40 vs 0.48). However, diagnostic accuracy of either PD or PAI was worse than GCL thickness. CONCLUSIONS: While PAI yielded better correlation with mean deviation and GCL thickness, and a slightly improved separation between patients with glaucoma and healthy controls, diagnostic accuracy was inferior compared with GCL thickness.

Bone Marrow-Derived Macrophages Enhance Vessel Stability in Modular Engineered Tissues.

IMPACT STATEMENT: This work demonstrates an effective method of enhancing the stability of a newly formed vasculature in modular engineered tissues in vivo through the counterintuitive implantation of allogeneic macrophages. Furthermore, we provide a detailed method for analyzing macrophage phenotype in vascularized explants and assess the role of added mesenchymal stromal cells (MSC) on that phenotype. Enhanced vascular stability may permit the development of increasingly large, clinically relevant tissues, fully permeated by blood vessels integrated with the host vasculature.

Maximizing Physician-Hospital Alignment: Lessons Learned From Effective Models of Joint Arthroplasty Care.

BACKGROUND: With recent healthcare reform efforts focusing on rewarding value instead of volume, it has become important for orthopedic surgeons to partner and align with their hospitals. We report our experience in aligning clinical and financial incentives with 6 health systems in our geographic area. METHODS: By managing the entire episode-of-care continuum for total hip and total knee arthroplasty patients, our standardized, evidence-based protocols have improved the quality of care for our joint arthroplasty patients. While most studies focus on cost through insurance claims data, we have been able to accurately determine the costs to our practice and each facility through time-driven activity-based costing. RESULTS: We have also achieved measureable claims and actual cost reduction by reducing unnecessary care, inappropriate variation in care, and avoidable complications through demand matching, risk stratification, and our nurse navigator program. Our joint ventures with our hospital partners in both specialty hospitals and our ambulatory surgery centers have also been critical to our success. CONCLUSION: Our experience demonstrates that large private practice groups can successfully align both clinical and financial incentives with healthcare systems to provide quality joint arthroplasty care at a lower cost.

An Assessment of the Safety of an Orthopedic Specialty Hospital: A 5-Year Experience.

One of the goals of orthopedic specialty hospitals is to provide safe and efficient care to medically optimized patients. The authors' orthopedic specialty hospital is a physician-owned, 24-bed facility that accommodates a multispecialty orthopedic practice in the areas of spine, hip and knee arthroplasty, shoulder and elbow, sports, foot and ankle, and hand surgery. The purpose of this study was to examine the first 5 years of an institutional experience with an orthopedic specialty hospital and to determine if any procedures were at increased risk of postoperative transfer. When higher-level emergency treatment was required, patients were appropriately and expeditiously transferred and treated at an acute care facility. Length of stay compared favorably with that in traditional acute care hospitals. The specialty hospital may be an appropriate model for delivery of care to medically screened patients in the United States. [Orthopedics. 2017; 40(4):223-229.].

Organizational Structural Design in Spine Care.

For a company to provide high value to its customers, its organization design is critical. As health care transitions to a value-based model, it is critical that spinal care organizations are structured in such a way that they can maximize value to both the patient and the payers. This article will discuss the 3 most common ways that an organization can be structured, and the benefits and problems of each design in spinal care.

Value-based Insurance Design.

The increasing awareness of the scarcity of health care resources is forcing the health care industry to improve quality while lowering the cost. One method by which employers and insurance companies are attempting to do this is with value-based insurance design. In these plans, patients pay a lower amount for certain services that are considered high value and a higher amount for services that are considered low value.

The Role of Incentives in Changing the Behavior of Spinal Care Providers: A Primer on Behavioral Economics in Health Care.

As spinal care transitions from individual practitioners working in a volume-based reimbursement system toward multidisciplinary health care organizations working in a population-based model with value-based reimbursement, it is critical that insurance companies, administrators, and spine care provider have a clear understanding of how incentives change physician behavior. This article will introduce the concept of behavior economics, and discuss 9 principles relevant to physician decision-making.

The Service-Profit Chain in Spine Surgery.

Medicine has always been a service industry (as opposed to a manufacturing industry), as there is a shift from volume to value in health care, this point is becoming increasingly important. The delivery of good care extends beyond the technical aspects of performing a complex operation or prescribing the right type of medicine. Intuitively physicians have always understood the value of the physician-patient relationship, and its correlation to a good outcome. As patients are increasingly being forced to spend a greater portion of their personal income on health care through high-deductible plans and larger co-pays, physicians have to differentiate themselves through the delivery of great service beyond the delivery of superior health outcomes. Understanding the service-profit chain can help physicians succeed in the transition to a value-based health care system.

Understanding Competition in Spine Care.

The changing landscape from volume to value represents a natural transformation in the health care industry. Increasingly provider groups are finding themselves responding to unfamiliar market forces. Whether explicit or implicit, competition is playing a larger role for the sustainability of providers. For spine care providers who are attempting to navigate the transition from volume to value, understanding the forces that shape competition in health care can help achieve success.

Understanding Business Models in Health Care.

The increasing focus on the costs of care is forcing health care organizations to critically look at their basic set of processes and activities, to determine what type of value they can deliver. A business model describes the resources, processes, and cost assumptions that an organization makes that will lead to the delivery of a unique value proposition to a customer. As health care organizations are beginning to transform their structure in preparation for a value-based delivery system, understanding business model theory can help in the redesign process.

Understanding Time-driven Activity-based Costing.

Transitioning to a value-based health care system will require providers to increasingly scrutinize their outcomes and costs. Although there has been a great deal of effort to understand outcomes, cost accounting in health care has been a greater challenge. Currently the cost accounting methods used by hospitals and providers are based off a fee-for-service system. As resources become increasingly scarce and the health care system attempts to understand which services provide the greatest value, it will be critically important to understand the true costs of delivering a service. An understanding of the true costs of a particular service will help providers make smarter decisions on how to allocate and utilize resources as well as determine which activities are nonvalue added. Achieving value will require providers to have a greater focus on accurate outcome data as well as better methods of cost accounting.

Innovation in Health Care Delivery.

As reimbursement transitions from a volume-based to a value-based system, innovation in health care delivery will be needed. The process of innovation begins with framing the problem that needs to be solved along with the strategic vision that has to be achieved. Similar to scientific testing, a hypothesis is generated for a new solution to a problem. Innovation requires conducting a disciplined form of experimentation and then learning from the process. This manuscript will discuss the different types of innovation, and the key steps necessary for successful innovation in the health care field.

Redesigning Health Care Organizations: The Influence of Government Policy and Methods of Payment.

Over the last 5 years, there has been a growing trend toward consolidation in the health care field. As reimbursement moves from a fee-for-service model to a value-based model, there will be continued pressure on physicians to either be a hospital employee or to be in a large multidisciplinary practice. This is largely due to the Accountable Care Act, which directs payers to utilize population-based cost analyses, rather than an individual patient-based analysis. To succeed in this environment, practices will have to break down traditional organizational barriers to create evidence-based algorithms for the treatment of individual diagnoses from the initial onset of symptoms until the resolution of symptoms.

The Role of Strategy in Health Care.

Significant changes are occurring in the health care field, and spine surgeons must have an understanding of business strategy if they are going to adapt to the new health care environment. Spine surgeons will be required to demonstrate how their service provides a unique value to their patients or else the patients will obtain care from competitors. Classic methods for demonstrating value such as academic prestige and superior clinical outcomes may no longer be sufficient in the evolving health care field, and surgeons will need to demonstrate a comprehensive and cost-effective treatment algorithm for a diagnosis. This article will discuss the basics of business strategy for the spine surgeon, and ways in which the surgeon may demonstrate value to their patients.