The Department of Veterans Affairs is developing, testing and evaluating the benefits of physicians' workstations as an aid to medical data capture in an outpatient clinic setting. The physician's workstation uses a graphical user interface to aid the clinician in recording encounter data. Various input devices including keyboard, mouse, pen, voice, barcode reader, and tablet are available on the workstations, and user preferences will be examined. Access to general services such as electronic mail and reference databases is also available. The workstation provides a wide variety of patient specific data from the hospital information system, including image data. The single data collection process by the clinician will also provide data for the cost recovery process.
The workflow in radiology departments has changed dramatically with the transition to digital PACS, especially with the shift from tile mode to stack mode display of volumetric images. With the increasing number of images in routinely captured datasets, the standard user interface devices (UIDs) become inadequate. One basic approach to improve the navigation of the stack mode datasets is to take advantage of alternative UIDs developed for other domains, such as the computer game industry. We evaluated three UIDs both in clinical practice and in a task-based experiment. After using the devices in the daily image interpretation work, the readers reported that both of the tested alternative UIDs were better in terms of ergonomics compared to the standard mouse and that both alternatives were more efficient when reviewing large CT datasets. In the task-based experiment, one of the tested devices was faster than the standard mouse, while the other alternative was not significantly faster. One of the tested alternative devices showed a larger number of traversed images during the task. The results indicate that alternative user interface devices can improve the navigation of stack mode datasets and that radiologists should consider the potential benefits of alternatives to the standard mouse.
Navigation; user interface; PACS; computed tomography
When holding a tablet computer with two hands, the touch keyboard configuration imposes postural constraints on the user because of the need to simultaneously hold the device and type with the thumbs. Designers have provided users with several possible keyboard configurations (device orientation, keyboard layout and location). However, potential differences in performance, usability and postures among these configurations have not been explored. We hypothesize that (1) the narrower standard keyboard layout in the portrait orientation leads to lower self-reported discomfort and less reach than the landscape orientation; (2) a split keyboard layout results in better overall outcomes compared to the standard layout; and (3) the conventional bottom keyboard location leads to the best outcomes overall compared to other locations. A repeated measures laboratory experiment of 12 tablet owners measured typing speed, discomfort, task difficulty, and thumb/wrist joint postures using an active marker system during typing tasks for different combinations of device orientation (portrait and landscape), keyboard layout (standard and split), and keyboard location (bottom, middle, top). The narrower standard keyboard with the device in the portrait orientation was associated with less discomfort (least squares mean (and S.E.) 2.9±0.6) than the landscape orientation (4.5±0.7). Additionally, the split keyboard decreased the amount of reaching required by the thumb in the landscape orientation as defined by a reduced range of motion and less MCP extension, which may have led to reduced discomfort (2.7±0.6) compared to the standard layout (4.5±0.7). However, typing speed was greater for the standard layout (127±5 char./min.) compared to the split layout (113±4 char./min.) regardless of device orientation and keyboard location. Usage guidelines and designers can incorporate these findings to optimize keyboard design parameters and form factors that promote user performance and usability for thumb interaction.
Target volume delineation is a critical, but time-consuming step in the creation of radiation therapy plans used in the treatment of many types of cancer. However, variability in target volume definitions can introduce substantial differences in resulting doses to tumors and critical structures. We developed TaCTICS, a web-based educational training software application targeted towards non-expert users. We report on a small, prospective study to evaluate the utility of this online tool in improving conformance of regions-of-interest (ROIs) with a reference set. Eight residents contoured a set of structures for a head-and-neck cancer case. Subsequently, they were provided access to TaCTICS as well as contouring atlases to allow evaluation of their contours in reference to other users as well as reference ROIs. The residents then contoured a second case using these resources. Volume overlap metrics between the users showed a substantial improvement following the intervention. Additionally, 66% of users reported that they found TaCTICS to be a useful educational tool and all participants reported they would like to use TaCTICS to track their contouring skills over the course of their residency.
OBJECTIVES—Schizophrenia may result from disturbed
attentional processes and/or defective internal cueing. Attention for
subsequent action within a cued movement task was therefore studied,
testing specific hypotheses of hemispheric dysfunction and of impaired
METHOD—Fifteen patients with schizophrenia and 15 matched controls were either cued or uncued when moving a pen to a
target on their right or left side with their right or left hand. Pen
tip position was sampled at 200 Hz on a WACOM SD420 graphics tablet for
subsequent kinematic analysis.
RESULTS—Patients with schizophrenia were slower
initiating rightwards movements without a cue. Patients also exhibited
reduced abductive/adductive differences in the shape of their movement
trajectories, implying differences in interhemispheric communication.
CONCLUSIONS—It is speculated that schizophrenia is
a form of cue dependent right hemineglect.
The purpose of this study is to assess the accuracy, precision, and rapidity of liver volumes calculated by using a freehand electromagnetic pen tablet contourtracing method as compared with the volumes calculated by using the standard optical mouse contourtracing method. The imaging data used as input for accuracy and precision testing were computed by software developed in our institution. This computer software can generate models of solid organs and allows both standard mouse-based and electromagnetic pen-driven segmentation (number of data sets, n = 70). The images used as input for rapidity testing was partly computed by modeling software (n = 70) and partly selected from contrast-enhanced computed tomography (CT) examinations (n = 12). Mean volumes and time required to perform the segmentation, along with standard deviation and range values with both techniques, were calculated. Student's t test was used to assess significance regarding mean volumes and time calculated by using both segmentation techniques on phantom and CT data sets. P value was also calculated. The mean volume difference was significantly lower with the use of the freehand electromagnetic pen as compared with the optical mouse (0.2% vs. 1.8%; P < .001). The mean segmentation time per patient was significantly shorter with the use of the freehand electromagnetic pen contourtracing method (354.5 vs. 499.1 s on phantoms; 457.4 vs. 610.0 s on CT images; P < .001). Freehand electromagnetic pen-based volumetric technique represents a technologic advancement over manual mouse-based contourtracing because of the superior statistical accuracy and sensibly shorter time required. Further studies focused on intra- and interobserver variability of the technique need to be performed before its introduction in clinical application.
Liver volumetry; computed tomography (CT); pen tablet; contour tracing
The QWERTY keyboard mediates communication for millions of language users. Here, we investigated whether differences in the way words are typed correspond to differences in their meanings. Some words are spelled with more letters on the right side of the keyboard and others with more letters on the left. In three experiments, we tested whether asymmetries in the way people interact with keys on the right and left of the keyboard influence their evaluations of the emotional valence of the words. We found the predicted relationship between emotional valence and QWERTY key position across three languages (English, Spanish, and Dutch). Words with more right-side letters were rated as more positive in valence, on average, than words with more left-side letters: the QWERTY effect. This effect was strongest in new words coined after QWERTY was invented and was also found in pseudowords. Although these data are correlational, the discovery of a similar pattern across languages, which was strongest in neologisms, suggests that the QWERTY keyboard is shaping the meanings of words as people filter language through their fingers. Widespread typing introduces a new mechanism by which semantic changes in language can arise.
Electronic supplementary material
The online version of this article (doi:10.3758/s13423-012-0229-7) contains supplementary material, which is available to authorized users.
Motor action; Meaning; Orthography; Typing; QWERTY; Valence
The role of computers in assisting physicians with patient care is rapidly advancing. One of the significant obstacles to efficient use of computers in patient care has been the unavailability of reasonably configured portable computers. Lightweight portable computers are becoming more attractive as physician data-management devices, but still pose a significant problem with bedside use. The advent of computers designed to accept input from a pen and having no keyboard present a usable computer platform to enable physicians to perform clinical computing at the bedside. This paper describes a prototype system to maintain an electronic "scut" sheet. SCUT makes use of pen-input and background rule checking to enhance patient care. GO Corporation's PenPoint Operating System is used to implement the SCUT project.
Vectors which possess a truncated niaD gene encoding nitrate reductase were developed to allow targeted gene integration during transformation of an niaD mutant Penicillium chrysogenum host. The Penicillium genes pcbC and penAB are immediately adjacent to each other and are divergently transcribed, with an intergenic control region serving as their promoters. Gene fusions were constructed with a reporter gene, uidA, which encodes beta-glucuronidase. The pcbC-penAB intergenic region was fused to the uidA gene in both orientations so that regulated expression of each structural gene could be investigated. These fusion genes were targeted to the chromosomal site of the niaD locus of P. chrysogenum, and their expression was examined under different growth conditions. The expression of each of these penicillin biosynthesis genes was found to be regulated by nitrogen repression, glucose repression, and growth stage control.
Three interaction techniques were evaluated for scrolling stack mode displays of volumetric data. Two used a scroll-wheel mouse: one used only the wheel, while another used a “click and drag” technique for fast scrolling, leaving the wheel for fine adjustments. The third technique used a Shuttle Xpress jog wheel. In a within-subjects design, nine radiologists searched stacked images for simulated hyper-intense regions on brain, knee, and thigh MR studies. Dependent measures were speed, accuracy, navigation path, and user preference. The radiologists considered the task realistic. They had high inter-subject variability in completion times, far larger than the differences between techniques. Most radiologists (eight out of nine) preferred familiar mouse-based techniques. Most participants scanned the data in two passes, first locating anomalies, then scanning for omissions. Participants spent a mean 10.4 s/trial exploring anomalies, with only mild variation between participants. Their rates of forward navigation searching for anomalies varied much more. Interaction technique significantly affected forward navigation rate (scroll wheel 5.4 slices/s, click and drag 9.4, and jog wheel 6.9). It is not clear what constrained the slowest navigators. The fastest navigator used a unique strategy of moving quickly just beyond an anomaly, then backing up. Eight naïve students performed a similar protocol. Their times and variability were similar to the radiologists, but more (three out of eight) students preferred the jog wheel. It may be worthwhile to introduce techniques such as the jog wheel to radiologists during training, and several techniques might be provided on workstations, allowing individuals to choose their preferred method.
Stack mode image navigation; user interaction devices; mouse scrolling interaction; jog-shuttle wheel
In current radiologists’ workstations, a scroll mouse is typically used as the primary input device for navigating image slices and conducting operations on an image. Radiological analysis and diagnosis rely on careful observation and annotation of medical images. During analysis of 3D MRI and CT volumes, thousands of mouse clicks are performed everyday, which can cause wrist fatigue. This paper presents a dynamic control-to-display (C-D) gain mouse movement method, controlled by an eyegaze tracker as the target predictor. By adjusting the C-D gain according to the distance to the target, the mouse click targeting time is reduced. Our theoretical and experimental studies show that the mouse movement time to a known target can be reduced by up to 15%. We also present an experiment with 12 participants to evaluate the role of eyegaze targeting in the realistic situation of unknown target positions. These results indicate that using eyegaze to predict the target position, the dynamic C-D gain method can improve pointing performance by 8% and reduce the error rate over traditional mouse movement.
User–computer interface; observer performance; radiology workstation; eye movements; image navigation; dynamic C-D; Fitts’ law
The accurate and expeditious collection of survey data by coordinators in the field is critical in the support of research studies. Early methods that used paper documentation have slowly evolved into electronic capture systems. Indeed, tools such as REDCap and others illustrate this transition. However, many current systems are tailored web-browsers running on desktop/laptop computers, requiring keyboard and mouse input. We present a system that utilizes a touch screen interface running on a tablet PC with consideration for portability, limited screen space, wireless connectivity, and potentially inexperienced and low literacy users. The system was developed using C#, ASP.net, and SQL Server by multiple programmers over the course of a year. The system was developed in coordination with UCLA Family Medicine and is currently deployed for the collection of data in a group of Los Angeles area clinics of community health centers for a study on drug addiction and intervention.
Tracer kinetic modeling with dynamic Positron Emission Tomography (PET) requires a plasma time-activity curve (PTAC) as an input function. Several image-derived input function (IDIF) methods that rely on drawing the region-of-interest (ROI) in large vascular structures have been proposed to overcome the problems caused by the invasive approach to obtaining the PTAC, especially for small animal studies. However, the manual placement of ROIs for estimating IDIF is subjective and labor-intensive, making it an undesirable and unreliable process. In this paper, we propose a novel hybrid clustering method (HCM) that objectively delineates ROIs in dynamic PET images for the estimation of IDIFs, and demonstrate its application to the mouse PET studies acquired with [18F]Fluoro-2-deoxy-2-D-glucose (FDG). We begin our HCM using K-means clustering for background removal. We then model the time-activity curves using polynomial regression mixture models in curve clustering for heart structure detection. The hierarchical clustering is finally applied for ROI refinements. The HCM achieved accurate ROI delineation in both computer simulations and experimental mouse studies. In the mouse studies the predicted IDIF had a high correlation with the gold standard, the PTAC derived from the invasive blood samples. The results indicate that the proposed HCM has a great potential in ROI delineation for automatic estimation of IDIF in dynamic FDG-PET studies.
Position Emission Tomography (PET); curve clustering; segmentation; image-derived input function
Insulin pen devices are used by approximately half of insulin users worldwide. The injection force of insulin pens is a key element in their design. This study aimed to demonstrate that the sanofi-aventis reusable ClikSTAR® (CS) pen has an improved injection force over existing insulin pens.
The injection force of four reusable insulin pens—Novopen® 4 (NP4; Novo Nordisk), Luxura® (LL; Eli Lilly and Co.), Berlipen® (BP; Haselmeier GmbH), and CS (sanofi-aventis)—was tested in a laboratory setting. Injection force was tested using two methods: six dispense rates between 6 and 24.66 U/s (constant volume flow rate) and constant button speeds of 4 and 8 mm/s.
The CS required a lower mean injection force versus NP4, LL, and BP at both doses and all dispense rates. Mean injection force was 45%, 126%, and 60% higher for NP4, LL, and BP versus CS, respectively (p < .05 for each of the comparisons), for a flow rate of 6 U/s at 60 U dose. Mean injection force in all pens increased with the dispense rate, but the injection force remained significantly lower for CS versus all other pens (p < .05). The injection force for CS was significantly lower for 60 U at 10 and 17.03 U/s than for 80 U.
The study demonstrated that CS pens require a lower injection force at a wide range of different injection speeds than other reusable insulin pens. This is an important benefit for patients with diabetes, especially those with limited dexterity.
Berlipen; ClikSTAR; injection force; insulin pens; Lilly Luxura; Novopen 4
Orbitofrontal Cortex (OFC) structural abnormality in schizophrenia has not been well characterized, probably due to marked anatomical variability and lack of consistent definitions. We previously reported OFC sulcogyral pattern alteration and its associations with social disturbance in schizophrenia, but OFC volume associations with psychopathology and cognition have not been investigated. We compared chronically treated schizophrenia patients with healthy control (HC) subjects, using a novel, reliable parcellation of OFC subregions and their association with cognition, especially the Iowa Gambling Task (IGT), and with schizophrenic psychopathology including thought disorder. Twenty-four patients with schizophrenia and 25 age-matched HC subjects underwent MRI. OFC Regions of Interest (ROI) were manually delineated according to anatomical boundaries: Gyrus Rectus (GR); Middle Orbital Gyrus (MiOG); and Lateral Orbital Gyrus (LOG). The OFC sulcogyral pattern was also classified. Additionally, MiOG probability maps were created and compared between groups in a voxel-wise manner. Both groups underwent cognitive evaluations using the IGT, Wisconsin Card SortingTest, and Trail Making Test (TMT). An 11% bilaterally smaller MiOG volume was observed in schizophrenia, compared with HC (F1,47=17.4, P= 0.0001). GR and LOG did not differ, although GR showed a rightward asymmetry in both groups (F1,47=19.2, P<0.0001). The smaller MiOG volume was independent of the OFC sulcogyral pattern, which differed in schizophrenia and HC (χ2=12.49, P= 0.002). A comparison of MiOG probability maps suggested that the anterior heteromodal region was more affected in the schizophrenia group than the posterior paralimbic region. In the schizophrenia group, a smaller left MiOG was strongly associated with worse `positive formal thought disorder' (r=−0.638, P= 0.001), and a smaller right MiOG with a longer duration of the illness (r=−0.618, P= 0.002). While schizophrenics showed poorer performance than HC in the IGT, performance was not correlated with OFC volume. However, within the HC group, the larger the right hemisphere MiOG volume, the better the performance in the IGT (r=0.541, P= 0.005), and the larger the left hemisphere volume, the faster the switching attention performance for the TMT, Trails B (r=−0.608, P= 0.003). The present study, applying a new anatomical parcellation method, demonstrated a subregion-specific OFC grey matter volume deficit in patients with schizophrenia, which was independent of OFC sulcogyral pattern. This volume deficit was associated with a longer duration of illness and greater formal thought disorder. In HC the finding of a quantitative association between OFC volume and IGT performance constitutes, to our knowledge, the first report of this association.
schizophrenia; orbitofrontal region; thought disorder; decision making; Iowa gambling task
The aim of this multinational (Canada, France, Germany, United Kingdom, and United States), task and interview-based study was to compare the ease of use and performance of the ClikSTAR® (sanofi-aventis, Paris, France) insulin pen with other commonly used reusable pens based on participant and interviewer assessments.
People with diabetes (n = 654) were asked to demonstrate four pens consecutively—ClikSTAR, Lilly Luxura® (Eli Lilly, Indianapolis, IN), and NovoPen® 3 and 4 (Novo Nordisk, Bagsvaerd, Denmark)—according to the respective instruction manuals. The endpoint was assessed by a rating from the participants and the interviewer. While the participants focused on the pen's ease of use, the interviewer considered the participants' difficulty in preparing and delivering a 40-unit dose and their requirement for help.
Twenty percent of U.S. participants and 24% of participants from the other countries had type 1 diabetes. Approximately 50% of participants in each group had prior insulin pen experience. A higher proportion of participants, including those with dexterity or visual impairments, reported ClikSTAR as easier to use than other pens (P < 0.05). Participants using ClikSTAR did not experience any difficulty in completing the tasks. The proportion of participants not requiring help in completing the tasks with ClikSTAR was rated as numerically higher than, or similar to, that observed with Lilly Luxura or NovoPen 3 or 4 (75%, 74%, 62%, and 65%, respectively). According to participants, ClikSTAR and NovoPen 4 emerged as the most highly rated pens.
In comparison with other pens, ClikSTAR was significantly easier to use, which, when taken together with overall performance, meets the need of people with diabetes.
Summary: Current web-based genome browsers require repetitious user input to
scroll over long distances, alter the drawing density of elements or zoom through multiple
orders of magnitude. Generally, either the server or the client is responsible for the
majority of data processing, resulting in either servers having to receive and handle data
relevant only to one user, or clients redundantly processing widely viewed data.
ChromoZoom pre-renders and caches general-use tracks into tiled images on the server and
serves them in an interactive web interface with inertial scrolling and precise, fluent
zooming via the mouse wheel or trackpad. Custom tracks in several formats can be rendered
by client-side code alongside the pre-rendered tracks, minimizing server load because of
user-specific rendering and eliminating the need to transmit private data. ChromoZoom
thereby enables rapid and simultaneous exploration of curated, experimental and personal
Availability: Human and yeast genome researchers may browse recent
assemblies within ChromoZoom at http://chromozoom.org/. Source code is available at http://github.com/rothlab/chromozoom/.
Supplementary data are available at Bioinformatics
Target volume delineation is a critical step in the creation of treatment plans in radiation therapy. However, intra-observer and inter-observer variability in target volume definitions can introduce substantial differences in resulting doses between treatments plans from different users and institutions Consequently, there is a need for tools that allow quantitative metrics to be collected and reported regarding inter-and intra-user performance in target volume delineation. We describe TaCTICS, a web-based educational training software application targeted towards residents and non-expert users. TaCTICS allows users to delineate target structures in DICOM-RT compatible formats using their preferred treatment planning system. After uploading the resulting structure file, users are provided a scoring of their structures based on comparison to reference sets derived from expert users using a variety of metrics for volume overlap and surface distances.
Deformable image registration (DIR) is an attractive method for automatic propagation of regions of interest (ROIs) in adaptive lung radiotherapy. This study investigates DIR for automatic contour propagation in adaptive Non Small Cell Lung Carcinoma patients.
Pre and mid-treatment fan beam 4D-kVCT scans were taken for 17 NSCLC patients. Gross tumour volumes (GTV), nodal-GTVs, lungs, esophagus and spinal cord were delineated on all kVCT scans. ROIs were propagated from pre- to mid-treatment images using three DIR algorithms. DIR-propagated ROIs were compared with physician-drawn ROIs on the mid-treatment scan using the Dice score and the mean slicewise Hausdorff distance to agreement (MSHD). A physician scored the DIR-propagated ROIs based on clinical utility.
Good agreement between the DIR-propagated and physician drawn ROIs was observed for the lungs and spinal cord. Agreement was not as good for the nodal-GTVs and esophagus, due to poor soft-tissue contrast surrounding these structures. 96% of OARs and 85% of target volumes were scored as requiring no or minor adjustments.
DIR has been shown to be a clinically useful method for automatic contour propagation in adaptive radiotherapy however thorough assessment of propagated ROIs by the treating physician is recommended.
Deformable image registration; Adaptive radiotherapy; NSCLC; Automatic contour propagation
People take account of the variability in their movements in a near-optimal manner in various visuo-motor tasks. Is knowledge of one’s variability needed for such near-optimal performance, or could it arise from responding to one’s success in previous attempts in some simple manner? We asked subjects to move a pen back and forth across a tablet to make a cursor move as quickly as possible between two targets. The cursor had to stop within the targets. Task difficulty was varied between blocks. Part of the variation in difficulty was explicit (three target sizes) whereas the rest had to be discovered during the movements (two mappings between the movements of pen and cursor). In all cases, subjects sped up after stopping within a target and slowed down after failing to do so. We interpret this as evidence that explicit knowledge of one’s variability is not necessary for performing close to optimally.
Fitts’ law; Movement timing; Motor learning; Speed-accuracy trade-off; Optimal performance
The uptake of insulin pen use has been slow in the United States, despite their advantages over the vial/ syringe. We present results of a United States subset of 150 patients with type 1/type 2 diabetes, who were enrolled in an open-label study, that assessed usability, pen features, and patient preferences for four prefilled insulin pens: SoloSTAR®, FlexPen®, Lilly disposable pen, and a prototype, Pen X. Overall, the SoloSTAR and FlexPen were more user-friendly; 95 and 88% of patients, respectively, completed the steps correctly (without safety/attach-needle step—deemed independent of device) versus the Lilly disposable pen (60%) and Pen X (61%; all p < 0.05). The SoloSTAR was rated highest most frequently for pen feature comparisons. Results suggest that the SoloSTAR and FlexPen could potentially facilitate insulin use in the United States.
disposable pen; FlexPen; insulin device; Lilly disposable pen; SoloSTAR; United States
This open-label, randomized, comparative crossover usability study investigated preference between durable insulin pens, NovoPen® 4 and NovoPen 3, among patients with types 1 and 2 diabetes.
In a timed test, 82 current NovoPen 3 users (mean age, 48.5 years) assessed intuitiveness of NovoPen 4. After timed training, this group and 34 insulin-naïve patients (mean age, 61.8 years) were randomized to a handling evaluation of NovoPen 4 followed by NovoPen 3, or vice versa, in which participants made three injections into a foam cushion. A device-specific questionnaire was filled out for each pen. A third questionnaire asked participants to compare pens.
Current NovoPen 3 users completed the intuitive assessment of NovoPen 4 in an average time of 1.94 min (range, 0.57–4.98 min). The training of insulin-naïve patients occurred in slightly less time with NovoPen 4 than with NovoPen 3 but did not reach significance (9.9 versus 11.5 min; p = .32). Survey responses showed that both groups had less difficulty and were more confident in handling NovoPen 4 than NovoPen 3; 96.3% of the NovoPen 3 users and 100% of the insulin-naïve group preferred to use NovoPen 4 (p < .0001).
Patients currently using NovoPen 3 or who were insulin naïve expressed a preference for NovoPen 4 in this study, reporting it to be simpler to learn and easier to use than NovoPen 3. NovoPen 4 may help facilitate insulin therapy among newly diagnosed patients and potentially improve adherence and treatment satisfaction among current NovoPen 3 users.
diabetes mellitus; insulin pen; NovoPen; preference
To evaluate the roles of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and optimum tracer kinetic parameters in the noninvasive grading of the glial brain tumors with histopathological grades (I–IV).
Materials and Methods
Twenty eight patients with histopathologically graded gliomas were imaged. Images with five flip angles were acquired before injection of gadolinium-DTPA and were processed to calculate the T1 value of each regions of interest (ROI). All the DCE-MRI data acquired during the injection were processed based on the MRI signal and pharmacokinetic models to establish concentration-time curves in the ROIs drawn within the tumors, counterlateral normal areas, and area of the individual artery input functions (iAIF) of each patient. A nonlinear least square fitting method was used to obtain tracer kinetic parameters. Kruskal-Wallis H-test and Mann-Whitney U-test were applied to these parameters in different histopathological grade groups for statistical differences (P<0.05).
Volume transfer coefficient (Ktrans) and extravascular extracellular space volume fraction (Ve) calculated by using iAIFs can be used not only to distinguish the low (i.e., I and II) from the high (i.e., III and IV) grade gliomas (P(Ktrans) <0.001 and PVe<0.001), but also grade II from III (P(Ktrans) =0.016 and PVe=0.033).
Ktrans is the most sensitive and specific parameter in the noninvasive grading, distinguishing the high (III and IV) from the low (I and II) grade and high grade III from low grade II gliomas.
MR perfusion imaging; gliomas; microvascular permeability; pharmacokinetics; grades of glioma
Computational neuroscientists frequently encounter the challenge of parameter fitting – exploring a usually high dimensional variable space to find a parameter set that reproduces an experimental data set. One common approach is using automated search algorithms such as gradient descent or genetic algorithms. However, these approaches suffer several shortcomings related to their lack of understanding the underlying question, such as defining a suitable error function or getting stuck in local minima. Another widespread approach is manual parameter fitting using a keyboard or a mouse, evaluating different parameter sets following the users intuition. However, this process is often cumbersome and time-intensive. Here, we present a new method for manual parameter fitting. A MIDI controller provides input to the simulation software, where model parameters are then tuned according to the knob and slider positions on the device. The model is immediately updated on every parameter change, continuously plotting the latest results. Given reasonably short simulation times of less than one second, we find this method to be highly efficient in quickly determining good parameter sets. Our approach bears a close resemblance to tuning the sound of an analog synthesizer, giving the user a very good intuition of the problem at hand, such as immediate feedback if and how results are affected by specific parameter changes. In addition to be used in research, our approach should be an ideal teaching tool, allowing students to interactively explore complex models such as Hodgkin-Huxley or dynamical systems.
In the current issue of Journal of Diabetes Science and Technology, Dr. Olsen and colleagues analyzed the attitudes of children, their caregivers, and health care professional towards the usability, functionality, and preference of the NovoPen® Echo (Novo Nordisk Inc., Princeton, NJ). A comparison is made to two other insulin pen devices with half-unit increment capability—the NovoPen Junior and the HumaPen® Luxura® (Eli Lilly and Company, Indianapolis, IN). Their results support the idea that the NovoPen Echo has the highest overall satisfaction among pen devices capable of delivering half-unit increments, is equally simple to assemble and inject, and has the added benefit of a simple recall memory function. A major concern is their finding that fewer adolescents dialed a dose correctly with NovoPen Echo than with the other two pens tested. Furthermore, the true test in validating their claims of the importance of this device lays in future studies, which should be undertaken to demonstrate that a preferred delivery device actually leads to improved compliance in children and adolescents with type 1 diabetes.
half-unit increments; insulin pen; memory function; pediatric