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Biomedical subjects

Elizabeth A Krupinski

Publications and source records attributed to Elizabeth A Krupinski.

At least 19 recordsLinked to original sources
PubMed2007

Choosing a radiology workstation: technical and clinical considerations.

Choosing a workstation for daily use in the interpretation of digital radiologic images can be a daunting task. There are numerous products available on the market, but differentiating among them and deciding on what is best for a particular environment can be confusing and frustrating. There is no "one-size-fits-all" workstation, so users must consider a variety of factors when choosing a workstation. This review summarizes the critical elements in a radiology workstation and the characteristics one should be aware of and look for in the selection of a workstation. Issues pertaining to both hardware and software aspects of medical workstations, including interface design, are reviewed, particularly as they may affect the interpretation process.

Data Display↗
PubMed2006

Accuracy of stepping-table lower extremity MR angiography with dual-level bolus timing and separate calf acquisition: hybrid peripheral MR angiography.

PURPOSE: To retrospectively evaluate the accuracy of hybrid peripheral magnetic resonance (MR) angiography by using conventional digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: This retrospective study protocol received approval from the Office of Sponsored Research at Northwestern University, which included review by the Office for the Protection of Research Subjects. Informed consent was waived for this HIPAA-compliant study. One hundred twenty-one consecutive patients (67 men: mean age, 66 years +/- 12 [standard deviation]; 54 women: mean age, 69 years +/- 14), who were referred for evaluation of peripheral vascular disease, underwent peripheral contrast material-enhanced MR angiography. By using a hybrid technique, two independent timing measurements were performed in the pelvis and calves followed by MR angiography of the calves and, subsequently, a pelvis-thigh stepping-table acquisition. Images were evaluated for extent of disease, on the basis of degree of stenosis; for venous contamination, on the basis of venous signal intensity; and for diagnostic quality, on the basis of diagnostic confidence of the observer. DSA correlation of the extent of vascular disease was available in 45 of these patients, which was used to evaluate the diagnostic power of the hybrid technique. RESULTS: For detection of stenosis greater than 50%, the hybrid technique had 95% sensitivity (P < .05), 95% specificity (P < .05), and 95% accuracy (P < .05). There was no significant venous contamination in any of the examinations performed with this technique. CONCLUSION: The hybrid peripheral MR angiography technique provides diagnostic-quality examinations and virtually eliminates venous contamination.

Adult↗
PubMed2006

Using a human visual system model to optimize soft-copy mammography display: influence of veiling glare.

RATIONALE AND OBJECTIVES: This project evaluated human observer performance and that of a human visual system model (JNDmetrix) to assess whether the veiling glare of a digital display influences observer performance during soft-copy interpretation of mammographic images for the detection of masses. MATERIALS AND METHODS: A set of 160 mammographic images, half containing a single mass, was processed to simulate four levels of veiling glare: none, comparable to a medical grade monochrome curved-screen cathode ray tube (CRT) display, double that of the CRT and quadruple that of the CRT. The images were shown to six observers in a randomized presentation order on a liquid crystal display (LCD) that had essentially no veiling glare. The images were also analyzed using the JNDmetrix human visual system model. RESULTS: Observer performance as measured using receiver operating characteristic techniques declined with increasing veiling glare (F = 6.884, P = .0035), with quadruple veiling glare yielding significantly lower performance than the lower veiling glare levels. The JNDmetrix model did not show a large reduction in performance as a function of veiling glare, and correlation with the human observer data was modest (0.588). CONCLUSIONS: Soft-copy display veiling glare can influence observer performance, but only at extreme levels. The impact of veiling glare on performance may be more pronounced for less experienced readers.

Glare↗
PubMed2006

Eye-movement study and human performance using telepathology virtual slides: implications for medical education and differences with experience.

A core skill in diagnostic pathology is light microscopy. Remarkably little is known about human factors that affect the proficiency of pathologists as light microscopists. The cognitive skills of pathologists have received relatively little attention in comparison with the large literature on human performance studies in radiology. One reason for this lack of formal visual search studies in pathology has been the physical restrictions imposed by the close positioning of a microscope operator's head to the microscope's eyepieces. This blocks access to the operator's eyes and precludes assessment of the microscopist's eye movements. Virtual slide microscopy now removes this barrier and opens the door for studies on human factors and visual search strategies in light microscopy. The aim of this study was to assess eye movements of medical students, pathology residents, and practicing pathologists examining virtual slides on a digital display monitor. Whole histopathology glass slide digital images, so-called virtual slides, of 20 consecutive breast core biopsy cases were used in a retrospective study. These high-quality virtual slides were produced with an array-microscope equipped DMetrix DX-40 ultrarapid virtual slide processor (DMetrix, Tucson, Ariz). Using an eye-tracking device, we demonstrated for the first time that when a virtual slide reader initially looks at a virtual slide his or her eyes are very quickly attracted to regions of interest (ROIs) within the slide and that these ROIs are likely to contain diagnostic information. In a matter of seconds, critical decisions are made on the selection of ROIs for further examination at higher magnification. We recorded: (1) the time virtual slide readers spent fixating on self-selected locations on the video monitor; (2) the characteristics of the ways the eyes jumped between fixation locations; and (3) x and y coordinates for each virtual slide marking the sites the virtual slide readers manually selected for zooming to higher ROI magnifications. We correlated the locations of the visually selected fixation locations and the manually selected ROIs. Viewing profiles were identified for each group. Fully trained pathologists spent significantly less time (mean, 4.471 seconds) scanning virtual slides when compared to pathology residents (mean, 7.148 seconds) or medical students (mean, 11.861 seconds), but had relatively prolonged saccadic eye movements (P < .0001). Saccadic eye movements are defined as eye movements between fixation locations. On the other hand, the pathologists spent significantly more time than trainees dwelling on the 3 locations they subsequently chose for zooming. Unlike either the medical students or the residents, the pathologists frequently choose areas for viewing at higher magnification outside of areas of foveal (central) vision. Eye movement studies of scanning pathways (scan paths) may be useful for developing eye movement profiles for individuals and for understanding the difference in performances between novices and experts. They may also be useful for developing new visual search strategies for rendering diagnoses on telepathology virtual slides.

Biopsy↗
PubMed2005

Differential use of image enhancement techniques by experienced and inexperienced observers.

Full-field digital mammography (FFDM) systems are currently being used to acquire mammograms in digital format, but digital displays are less than ideal compared to traditional film-screen display. Certain physical properties of softcopy displays [e.g., modulation transfer function (MTF)] are less than optimal compared to film. We developed methods to compensate for some of these softcopy display deficiencies, based on careful physical characterization of the displays and image-processing software. A series of 100 FFDM and 60 digitized images was shown to six observers-half experienced (mammographers) and half inexperienced (radiology residents). The observers had to decide if a mass or microcalcification cluster was present and classify it as benign or malignant. A window could be activated that brought the image detail within the window to full resolution and corrected for the nonisotropic MTF of the Cathode Ray Tube (CRT) display. Experienced readers had better diagnostic performance and took less time to view the images. Experienced readers used window/level more than inexperienced readers, but inexperienced readers used magnification and the MTF compensation tool more often. Use of the magnification and the MTF tool increased reader decision confidence. Experienced and inexperienced readers use image-processing tools differently, with certain tools increasing reader confidence. Understanding how observers use image-processing tools may help in the development of better and more automated user interfaces.

Analysis of Variance↗
PubMed2005

Visual search of mammographic images: influence of lesion subtlety.

RATIONALE AND OBJECTIVES: The goal of this study is to determine whether mammographic lesion subtlety influences the detection accuracy and visual search parameters of radiologists. MATERIALS AND METHODS: Six radiologists searched a set of 20 mammograms with at least two lesions per image (masses and/or microcalcifications). Eye position was recorded. False-negative (FN) and true-positive (TP) decisions were correlated with lesion subtlety and visual search parameters of time to first hit, total dwell time, and number of return fixations. RESULTS: Lesions with lower subtlety ratings were detected later in the search than more obvious ones (FN later than TP decisions). When subtler lesions were detected (TP), dwell time was longer than for more obvious lesions, but FN decisions received shorter total dwell. Subtler lesions, when detected (TP), received more total fixation clusters than more obvious ones, but FN decisions received fewer. CONCLUSION: Subtle mammographic lesions are associated with significantly different visual search parameters than obvious lesions, explaining in part why they are missed more often. Developing tools to improve lesion visibility may improve detection.

Analysis of Variance↗
PubMed2005

On-axis and off-axis viewing of images on CRT displays and LCDs: observer performance and vision model predictions.

RATIONALE AND OBJECTIVES: Although cathode-ray tube (CRT) displays typically are used for softcopy display of radiographs in the digital reading environment, liquid crystal displays (LCDs) currently are being used as an alternative. LCDs have many desirable viewing properties compared with a CRT, but significant image degradation can occur with off-axis viewing. This study compares observer performance and predictions from a human visual system model for on-axis and off-axis viewing for CRT displays versus LCDs. MATERIALS AND METHODS: A set of mammograms with different lesion contrasts (n = 400) were shown to six radiologists on CRT and LCD monitors, once on-axis and once off-axis. Observer performance was measured by using receiver operating characteristic techniques. Performance was correlated with results of a human vision model designed to predict observer performance (just noticeable difference [JND]metrix model). Two approaches were used to generate model metrics; a paired discrimination and channelized model observer approach. RESULTS: The performance of human observers indicated that on-axis viewing with the LCD was better than with the CRT, but off-axis viewing was significantly better with the CRT than LCD (F = 8.8175; P < .0001). The paired discrimination model correctly predicted on-axis, but not off-axis, results. The channelized model observer correctly predicted both on- and off-axis results. CONCLUSION: Off-axis viewing of radiographic images on an LCD monitor degrades human observer performance significantly compared with a CRT display. Care should be taken in the clinic to avoid off-axis viewing during diagnostic interpretation.

Breast Neoplasms↗
PubMed2005

The Arizona Telemedicine Program business model.

The Arizona Telemedicine Program (ATP) was established in 1996 when state funding was provided to implement eight telemedicine sites. Since then the ATP has expanded to connect 55 health-care organizations through a membership programme formalized through legal contracts. The ATP's membership model is based on an application service provider (ASP) concept, whereby organizations can share services at lower cost; that is, the ATP acts as a broker for services. The membership fee schedule is flexible, allowing clients to purchase only those services desired. An annual membership fee is paid by every user, based on the services requested. The membership programme income has provided a steady revenue stream for the ATP. The membership-derived revenue represented 30% of the ATP's 2.6 million dollars total income during fiscal year 2003/04.

Arizona↗
PubMed2005

A review of the first five years of the University of Arizona telepsychiatry programme.

We performed a retrospective review of the first five years of activity in the University of Arizona Telepsychiatry Programme. The programme began in 1998 as part of a telemedicine service for underserved rural areas. Over the first five years, 1086 teleconsultations were carried out for a total of 206 patients. There were 159 adult (77%) and 47 paediatric patients (23%). During the study period, the racial/ethnic diversity of the paediatric patients increased, as did the number of follow-up visits for adult patients (average 5.3/patient). These trends suggested that telepsychiatry became an integral part of the mental health service system at the six referring sites. Adult patients completed 81 satisfaction surveys (51%) and psychiatrists completed 47 (23%). The responses showed that providers and patients found telepsychiatry services satisfactory, although in a minority of teleconsultations (18% for providers and 17% for patients) equipment problems were distracting. The continued use of the services suggests that the telepsychiatry programme fills a service gap in rural areas of the state.

Adolescent↗
PubMed2004

Use of a human visual system model to predict observer performance with CRT vs LCD display of images.

This Project evaluated a human visual system model (JNDmetrix) based on just noticeable difference (JND) and frequency-channel vision-modeling principles to assess whether a Cathode ray tube (CRT) or a liquid crystal display (LCD) monochrome display monitor would yield better observer performance in radiographic interpretation. Key physical characteristics, such as veiling glare and modulation transfer function (MTF) of the CRT and LCD were measured. Regions of interest from mammographic images with masses of different contrast levels were shown once on each display to six radiologists using a counterbalanced presentation order. The images were analyzed using the JNDmetrix model. Performance as measured by receiver operating characteristic (ROC) analysis was significantly better overall on the LCD display (P = 0.0120). The JNDmetrix model predicted the result (P = 0.0046) and correlation between human and computer observers was high (r (2) (quadratic) = 0.997). The results suggest that observer performance with LCD displays is superior to CRT viewing, at least for on-axis viewing.

Breast Neoplasms↗
PubMed2004

An array microscope for ultrarapid virtual slide processing and telepathology. Design, fabrication, and validation study.

This paper describes the design and fabrication of a novel array microscope for the first ultrarapid virtual slide processor (DMetrix DX-40 digital slide scanner). The array microscope optics consists of a stack of three 80-element 10 x 8-lenslet arrays, constituting a "lenslet array ensemble." The lenslet array ensemble is positioned over a glass slide. Uniquely shaped lenses in each of the lenslet arrays, arranged perpendicular to the glass slide constitute a single "miniaturized microscope." A high-pixel-density image sensor is attached to the top of the lenslet array ensemble. In operation, the lenslet array ensemble is transported by a motorized mechanism relative to the long axis of a glass slide. Each of the 80 miniaturized microscopes has a lateral field of view of 250 microns. The microscopes of each row of the array are offset from the microscopes in other rows. Scanning a glass slide with the array microscope produces seamless two-dimensional image data of the entire slide, that is, a virtual slide. The optical system has a numerical aperture of N.A.= 0.65, scans slides at a rate of 3 mm per second, and accrues up to 3,000 images per second from each of the 80 miniaturized microscopes. In the ultrarapid virtual slide processing cycle, the time for image acquisition takes 58 seconds for a 2.25 cm2 tissue section. An automatic slide loader enables the scanner to process up to 40 slides per hour without operator intervention. Slide scanning and image processing are done concurrently so that post-scan processing is eliminated. A virtual slide can be viewed over the Internet immediately after the scanning is complete. A validation study compared the diagnostic accuracy of pathologist case readers using array microscopy (with images viewed as virtual slides) and conventional light microscopy. Four senior pathologists diagnosed 30 breast surgical pathology cases each using both imaging modes, but on separate occasions. Of 120 case reads by array microscopy, there were 3 incorrect diagnoses, all of which were made on difficult cases with equivocal diagnoses by light microscopy. There was a strong correlation between array microscopy vs. "truth" diagnoses based on surgical pathology reports. The kappa statistic for the array microscopy vs. truth was 0.96, which is highly significant (z=10.33, p <0.001). There was no statistically significant difference between rates of agreement with truth between array microscopy and light microscopy (z=0.134, p >0.05). Array microscopy and light microscopy did not differ significantly with respect to the number/percent of correct decisions rendered (t=0.552, p=0.6376) or equivocal decisions rendered (t=2.449, p=0.0917). Pathologists rated 95.8% of array microscopy virtual slide images as good or excellent. None were rated as poor. The mean viewing time for a DMetrix virtual slide was 1.16 minutes. The DMetrix virtual slide processor has been found to reduce the virtual slide processing cycle more than 10 fold, as compared with other virtual slide systems reported to date. The virtual slide images are of high quality and suitable for diagnostic pathology, second opinions, expert opinions, clinical trials, education, and research.

Equipment Design↗
PubMed2004

Expense comparison of a telemedicine practice versus a traditional clinical practice.

This paper compares the expenses of a telemedicine program to those of a traditional clinical practice using data from two fiscal years (FY) 1998/1999 and 2000/2001. As part of that evaluation, we compared expenses of the University of Arizona's clinical practice group, the University Physicians Incorporated (UPI), to those of the Arizona Telemedicine Program (ATP) practice. For this study, we used the reporting categories published in the year-end UPI financial statement. These categories included clinical services, administration, equipment depreciation, and overhead. Results showed that clinical service expenses and administrative expenses for FY 2000/2001 were higher in the traditional UPI practice, whereas equipment depreciation and overhead expenses are higher in the telemedicine practice. This differs somewhat from FY 1998/1999, where clinical expenses and overhead were higher in the UPI practice and administration and equipment depreciation were higher in the telemedicine practice. We will discuss the relevance of these results and the critical factors that contribute to these differences.

Arizona↗
PubMed2004

Clinical encounters costing for telemedicine services.

The Arizona Telemedicine Program (ATP) has developed a costing model that includes a number of factors contributing to the cost of providing services via telemedicine and generates a per-encounter cost. We first developed the model in 1999 and in this paper used it to analyze clinical services for the fiscal year 2000/2001. We evaluated the calculated weighted cost for providing those services via telemedicine as compared to the cost of providing those services "face-to-face." The cost of providing services via telemedicine was found to be lower when a patient had to travel 127.5 miles or more to receive clinical services. Our study provides analysis of the factors, their contribution to costs, as well as some factors, which are pertinent, but are more problematic to calculate. In this paper, we discuss the relevance of these results as they relate to telemedicine programs and a possible means to reduce costs even further.

Arizona↗
PubMed2004

Effect of camera resolution and bandwidth on facial affect recognition.

This preliminary study explored the effect of camera resolution and bandwidth on facial affect recognition, an important process and clinical variable in mental health service delivery. Sixty medical students and mental health-care professionals were recruited and randomized to four different combinations of commonly used teleconferencing camera resolutions and bandwidths: (1) one chip charged coupling device (CCD) camera, commonly used for VHSgrade taping and in teleconferencing systems costing less than $4,000 with a resolution of 280 lines, and 128 kilobytes per second bandwidth (kbps); (2) VHS and 768 kbps; (3) three-chip CCD camera, commonly used for Betacam (Beta) grade taping and in teleconferencing systems costing more than $4,000 with a resolution of 480 lines, and 128 kbps; and (4) Betacam and 768 kbps. The subjects were asked to identify four facial affects dynamically presented on videotape by an actor and actress presented via a video monitor at 30 frames per second. Two-way analysis of variance (ANOVA) revealed a significant interaction effect for camera resolution and bandwidth (p = 0.02) and a significant main effect for camera resolution (p = 0.006), but no main effect for bandwidth was detected. Post hoc testing of interaction means, using the Tukey Honestly Significant Difference (HSD) test and the critical difference (CD) at the 0.05 alpha level = 1.71, revealed subjects in the VHS/768 kbps (M = 7.133) and VHS/128 kbps (M = 6.533) were significantly better at recognizing the displayed facial affects than those in the Betacam/768 kbps (M = 4.733) or Betacam/128 kbps (M = 6.333) conditions. Camera resolution and bandwidth combinations differ in their capacity to influence facial affect recognition. For service providers, this study's results support the use of VHS cameras with either 768 kbps or 128 kbps bandwidths for facial affect recognition compared to Betacam cameras. The authors argue that the results of this study are a consequence of the VHS camera resolution/bandwidth combinations' ability to improve signal detection (i.e., facial affect recognition) by subjects in comparison to Betacam camera resolution/bandwidth combinations.

Adult↗
PubMed2004

Continuing education via telemedicine: analysis of reasons for attending or not attending.

This study analyzed factors that influence the decision to attend or not attend tele-education broadcasts via a telemedicine network for continuing education (CE) credits. A questionnaire was developed and sent to all participating sites on our telemedicine network that have attended CE broadcasts. The majority of respondents attend specific types of broadcasts, receiving less than 25% of their CE credits from the tele-education broadcasts. Factors most influencing the decision to attend a broadcast include interest in the topic and perceived utility of the information. The most common reason influencing the decision not to attend is an explicit preference for attending conferences. Tele-education broadcasts may supplement other CE activities but may not replace them. The attraction of attending conferences in person is very high and may be especially so for health-care professionals in rural environments.

Attitude of Health Personnel↗