An integrative Bayesian approach to matrix‐based analysis in neuroimaging

Understanding the correlation structure associated with brain regions is a central goal in neuroscience, as it informs about interregional relationships and network organization. Correlation structure can be conveniently captured in a matrix that indicates the relationships among brain regions, which could involve electroencephalogram sensors, electrophysiology recordings, calcium imaging data, or functional magnetic resonance imaging (FMRI) data—We call this type of analysis matrix‐based analysis, or MBA. Although different methods have been developed to summarize such matrices across subjects, including univariate general linear models (GLMs), the available modeling strategies tend to disregard the interrelationships among the regions, leading to “inefficient” statistical inference. Here, we develop a Bayesian multilevel (BML) modeling framework that simultaneously integrates the analyses of all regions, region pairs (RPs), and subjects. In this approach, the intricate relationships across regions as well as across RPs are quantitatively characterized. The adoption of the Bayesian framework allows us to achieve three goals: (a) dissolve the multiple testing issue typically associated with seeking evidence for the effect of each RP under the conventional univariate GLM; (b) make inferences on effects that would be treated as “random” under the conventional linear mixed‐effects framework; and (c) estimate the effect of each brain region in a manner that indexes their relative “importance”. We demonstrate the BML methodology with an FMRI dataset involving a cognitive‐emotional task and compare it to the conventional GLM approach in terms of model efficiency, performance, and inferences. The associated program MBA is available as part of the AFNI suite for general use.     

Cost incentives for peripheral angioplasty

Hospital costs and length of stay for 86 patients with peripheral vascular disease treated by bypass or percutaneous transluminal angioplasty (PTA) were assessed. The length of stay averaged 4-4.5 times longer, and the total hospital charge was 3-3.7 times greater, for bypass than for PTA. These charges are discussed in relation to current diagnosis-related groups (DRGs) and the allowed reimbursement from the Federal Prospective Payment System. In appropriately selected patients with peripheral vascular disease, PTA should be the treatment of choice from both medical and financial points of view.     

Contrast medium-induced adverse reactions: economic outcome

Because the cost of managing an expected greater number of adverse reactions when high-osmolality contrast media (HOM) are used could offset the higher material cost of low-osmolality contrast media (LOM), a prospective study was done of 795 inpatients undergoing any of four procedures involving intravascular injection of HOM: cardiac catheterization, peripheral angiography, head computed tomography (CT), or body CT. The resources used in managing HOM-induced adverse reactions were measured, and the costs of these resources were estimated. Four hundred five patients (51%) had adverse reactions. Reactions were grouped into three classes according to their severity. Class 1 (mild) reactions occurred in 358 patients (45%), class 2 (moderate) reactions occurred in 44 patients (6%), and class 3 (severe) reactions occurred in three patients (0.4%). Ninety-nine patients (12%) consumed resources as a result of an adverse reaction. The average cost of these resources per patient undergoing examination was $1.07 to the radiology department, $5.83 to the hospital, and $12.93 to a charge-paying insurer. Mean (+/- standard deviation) cost to the hospital for managing class 1, class 2, and class 3 reactions were $2.52 +/- $5.33, $24 +/- $54, and $910 +/- $749, respectively. By comparison, the difference in material cost of HOM versus LOM ranged from $93 for body CT to $179 for cardiac catheterization. Even if LOM were to induce no adverse reactions, the increased material cost associated with universal substitution of LOM for HOM would be greater than the expected cost of managing adverse reactions when HOM are used.     

Quality assessment of randomized controlled trials of contrast media

Numerous randomized controlled trials (RCTs) have been conducted to define the relative benefits of low-osmolality contrast media (LOM) and high-osmolality contrast media (HOM). Because of the clinical and economic significance of the conclusions drawn from these RCTs, the authors used a standardized instrument to evaluate the quality of study design and data analysis of 100 RCTs published between 1982 and 1987 that compared LOM and HOM. The mean quality score (+/- standard deviation) was 39 +/- 12 (maximum possible score, 100). The largest number of patients studied in any RCT was 435; the smallest was five. A majority of the RCTs received high scores on three attributes of quality, intermediate scores on seven, and low scores on nine. These results underscore the difficulty of designing, performing, analyzing, and reporting high-quality RCTs. Nevertheless, limitations in study design and data analysis need to be considered when interpreting results of these RCTs. Future RCTs comparing LOM and HOM should be performed with greater attention to basic elements of good study design and data analysis.     

Upper-extremity venography using digital subtraction angiography

Venography to evaluate the patency of upper-extremity veins was performed with digital subtraction angiography (DSA) and conventional angiography. Venous thrombosis was easily diagnosed, and the innominate veins and superior vena cava were more easily visualized using DSA. Iodine concentration for DSA was one-third that of conventional venography, and the examination time was reduced by 50% using DSA. Patient comfort and acceptance were greater with DSA. DSA is a superior technique for upper-extremity vein evaluation in cooperative patients.     

Sexual assault nurse examiners' experiences providing expert witness court testimony

Nurses from a national random sample of SANE programs were interviewed about their most recent experience providing expert witness court testimony (N = 110). Forty-three percent of the SANEs characterized this experience "fine" with no difficulties, but 58% mentioned that they had encountered problems. Challenges they faced while testifying are explored in depth and implications for forensic nursing practice are discussed.     

Movements of Atlantic Sturgeon of the Gulf of Maine Inside and Outside of the Geographically Defined Distinct Population Segment

Identification of potential critical habitat, seasonal distributions, and movements within and between river systems is important for protecting the Gulf of Maine (GOM) distinct population segment of Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus. To accomplish these objectives, we captured Atlantic Sturgeon from four GOM rivers (Penobscot, Kennebec system, Saco, and Merrimack) and tagged 144 individuals (83.3–217.4 cm TL) internally with uniquely coded acoustic transmitters. Tagged fish were detected from 2006 to 2014 by primary receiver arrays that were deployed in the four GOM rivers or were detected opportunistically on a secondary group of receivers deployed within the GOM and along the continental shelf. Tagged Atlantic Sturgeon were documented at three spawning areas in the Kennebec system in June and July, including an area that became accessible in 1999 when Edwards Dam was removed. The majority (74%) of tagged fish were detected in the estuaries of the four GOM rivers, primarily in May–October. They spent most of their time in a 45-km reach within the Kennebec system but occupied more limited areas (≤5-km reach) within the Penobscot, Saco, and Merrimack rivers. Approximately 70% of the tagged fish were detected in GOM coastal waters and aggregated in the Bay of Fundy (May–January), offshore of the Penobscot River (September–February and May), offshore of the Kennebec River (September–February), in Saco Bay and the Scarborough River (July–November), and along the eastern Massachusetts coast between Cape Ann and Cape Cod (April–February). Nine tagged Atlantic Sturgeon (7%) left the GOM; three of those individuals moved north as far as Halifax, Nova Scotia, Canada, and six moved south as far as the James River, Virginia. Information obtained in this study has been used to make recommendations to avoid or reduce the impacts of in-water projects on Atlantic Sturgeon.

Received July 15, 2016; accepted November 27, 2016     

Altered segregation between task-positive and task-negative regions in mild traumatic brain injury

Changes in large-scale brain networks that accompany mild traumatic brain injury (mTBI) were investigated using functional magnetic resonance imaging (fMRI) during the N-back working memory task at two cognitive loads (1-back and 2-back). Thirty mTBI patients were examined during the chronic stage of injury and compared to 28 control participants. Demographics and behavioral performance were matched across groups. Due to the diffuse nature of injury, we hypothesized that there would be an imbalance in the communication between task-positive and Default Mode Network (DMN) regions in the context of effortful task execution. Specifically, a graph-theoretic measure of modularity was used to quantify the extent to which groups of brain regions tended to segregate into task-positive and DMN sub-networks. Relative to controls, mTBI patients showed reduced segregation between the DMN and task-positive networks, but increased functional connectivity within the DMN regions during the more cognitively demanding 2-back task. Together, our findings reveal that patients exhibit alterations in the communication between and within neural networks during a cognitively demanding task. These findings reveal altered processes that persist through the chronic stage of injury, highlighting the need for longitudinal research to map the neural recovery of mTBI patients.