Predicting climate change impacts on poikilotherms using physiologically guided species abundance models.

Poikilothermic animals comprise most species on Earth and are especially sensitive to changes in environmental temperatures. Species conservation in a changing climate relies upon predictions of species responses to future conditions, yet predicting species responses to climate change when temperatures exceed the bounds of observed data is fraught with challenges. We present a physiologically guided abundance (PGA) model that combines observations of species abundance and environmental conditions with laboratory-derived data on the physiological response of poikilotherms to temperature to predict species geographical distributions and abundance in response to climate change.

SPIE Medical Imaging 50th anniversary: history of the Image Perception, Observer Performance, and Technology Assessment Conference.

As SPIE Medical Imaging celebrates its 50th anniversary, we reflect on the history of the Image Perception, Observer Performance, and Technology Assessment Conference and its importance within the SPIE Medical Imaging Symposium and the greater medical imaging community.

The place of medical image perception in 21st-century health care.

An image that is not perceived and interpreted can have no positive impact on health care. In this article, the authors review publicly available data and the published literature concerning the unitary event of the perception and interpretation of medical images. Their review shows that this event occurs as frequently as do major medical, public health, and public safety events in the United States; constitutes a significant economic activity; and makes up a significant portion of hospital-based health care in the United States.

History of research in medical image perception.

Human observers engage in 2 interrelated processes when interpreting medical images: perception and analysis. Perception is the unified awareness of the content of a displayed image that is present while the stimulus is on. Analysis is determining the meaning of the perception in the context of the medical problem that initiated the acquisition of the image.

Holistic component of image perception in mammogram interpretation: gaze-tracking study.

Purpose: To test the hypothesis that rapid and accurate performance of the proficient observer in mammogram interpretation involves a shift in the mechanism of image perception from a relatively slow search-to-find mode to a relatively fast holistic mode.

Materials And Methods: This HIPAA-compliant study had institutional review board approval, and participant informed consent was obtained; patient informed consent was not required. The eye positions of three full-time mammographers, one attending radiologist, two mammography fellows, and three radiology residents were recorded during the interpretation of 20 normal and 20 subtly abnormal mammograms.

Pulmonary nodule detection in CT images with quantized convergence index filter.

A novel filter termed quantized convergence index filter (QCI filter) that is capable of enhancing the conspicuity of rounded lesions is proposed as part of a CAD (computer-aided diagnosis) scheme for detecting pulmonary nodules in computed tomography (CT) images. In this filter and its predecessor, the convergence index filter (CI filter), the output at a pixel represents the degree of convergence toward the pixel shown by the directions of gray-level gradients at surrounding pixels. The QCI filter and the CAD scheme were evaluated using five clinical datasets containing 50 nodules.

Perceptually based FROC analysis.

Rationale And Objectives: Analysis of reading data when cases have multiple targets and/or the reader is required to localize targets is difficult. One approach to this free-response operating characteristic (FROC) problem is for images to be segmented (eg, with quadrants) by the investigator and a segment-level analysis be conducted with the case as a nesting factor. In this report, we introduce an alternative method that uses the visual scan path of the reader to segment the image.

Gadodiamide T1 relaxivity in brain tissue in vivo is lower than in saline.

In vivo measurements of gadodiamide (Gd-DTPA-BMA) T(1) relaxivity were performed at 4.7 T in injured and normal rat brains. Cerebral lesions were induced in nine rats by a localized freezing method.

A novel method for analysis of TOMROP data.

Purpose: To develop an efficient method for extracting maps of the corrected T1 from images generated using the T One by Multiple Read Out Pulses (TOMROP) sequence.

Materials And Methods: An expression is developed for the true T1 in terms of the parameters from a three-parameter fit of the TOMROP data. Solutions of gadodiamide in normal saline with concentrations of 0.

Mixture distribution analysis of a computer assisted diagnostic method for the evaluation of pulmonary nodules on computed tomography scan.

Rationale And Objectives: To compare the effectiveness of a new computational scheme for pulmonary nodule detection in computed tomography images against human observers.

Materials And Methods: The study involved evaluation of 81 potential nodules by four radiologists. Each radiologist separately evaluated the potential nodules and provided a confidence level for the presence of pulmonary nodules.

The perception of breast cancers--a spatial frequency analysis of what differentiates missed from reported cancers.

The primary detector of breast cancer is the human eye. Radiologists read mammograms by mapping exogenous and endogenous factors, which are based on the image and observer, respectively, into observer-based decisions. These decisions rely on an internal schema that contains a representation of possible malignant and benign findings.

The digital imaging workstation. 1990.

Picture archiving and communication systems (PACS) are expected to convert film-based radiology into a computer-based digital environment, with associated cost savings and improved physician communication. The digital workstation will be used by physicians to display these “soft-copy” images; however, difficult technical challenges must be met for the workstation to compete successfully with the familiar viewbox. Issues relating to image perception and the impact on physicians’ practice must be carefully considered.

Measurement of observer agreement.

Statistical measures are described that are used in diagnostic imaging for expressing observer agreement in regard to categorical data. The measures are used to characterize the reliability of imaging methods and the reproducibility of disease classifications and, occasionally with great care, as the surrogate for accuracy. The review concentrates on the chance-corrected indices, kappa and weighted kappa.

The effect of PACS on the time required for technologists to produce radiographic images in the emergency department radiology suite.

The purpose of this study was to evaluate the effect of a switch to a filmless image management system on the time required for technologists to produce radiographic images in the emergency department (ED) after controlling for exam difficulty and a variable workload. Time and motion data were collected on patients who had radiographic images taken while being treated in the emergency department over the 3 1/2-year period from April 1997 to November 2000. Event times and demographic data were obtained from the radiology information system, from the hospital information system, from emergency department records, or by observation by research coordinators.

Time course of perception and decision making during mammographic interpretation.

Objective: This article describes the time course of lesion detection on digital mammograms using data about both eye position and decision time to compare performance between experienced mammographers and trainees. Research indicates that a longer decision time works against performance in the interpretation of chest radiographs because the likelihood of error is increased, particularly for trainees. Is this relation between decision time and performance also true for interpreting mammograms? Is there an optimal decision time-performance trade-off for detecting breast lesions?

Materials And Methods: Six radiology trainees (experience, 302-976 cases) and three mammographers (experience, 3000-5000 cases per year) reviewed 40 test cases.

The perception of breast cancer: what differentiates missed from reported cancers in mammography?

Rationale And Objectives: Mammographers map endogenous and exogenous factors into decisions whether to report the presence of a malignant finding in a mammogram case. Thus, to understand how image-based elements are translated into observer-based decisions, the authors used spatial frequency analysis to model the areas on mammograms that attracted visual attention, in addition to the areas localized as abnormal.

Materials And Methods: Four mammographers read 40 two-view mammogram cases, of which 30 contained at least one malignant lesion visible on one or two views.

Radiology services in emergency medicine residency programs: a national survey.

Objectives: To determine who reads plain film radiographs, how quickly radiologists' interpretations are available, how many initial readings require correction, and how satisfied emergency physicians (EPs) are with radiology in emergency departments (EDs) with emergency medicine (EM) residency programs.

Methods: A questionnaire was sent to the chairs of all U.S.

An automated results notification system for PACS.

The purpose of this study was to determine if the interval between an examination being ordered by an Emergency Department physician and his or her review of the report and images could be shortened by notifying the physician that the results were available. This hypothesis was based on work done previously in the Medical Intensive Care Unit that showed that physicians would wait to review results for a time considerably longer than the time required for the radiologist to review the images and provide a preliminary report. The software developments operate properly and show that even simple integration of multiple information systems (PACS, RIS, speech recognition) can provide useful features.

From being a radiologist to watching a radiologist: impact of filmless operation on the training of radiology residents.

Rationale And Objectives: The authors performed this study to investigate the impact of changing from a film-based image interpretation system to one using digital image workstations on the training of radiology residents in the interpretation of radiographs.

Materials And Methods: Data were collected during a period when a conventional system of image interpretation with hard-copy images and multiviewers was used and during a period when digital image workstations were used. During each period, it was noted whether the first interpretation of the radiographs was performed by a radiology resident, by an attending radiologist, or as a group effort including both an attending radiologist and a radiology resident(s).

Prolonged general anesthesia in MR studies of rats.

Rationale And Objectives: Magnetic resonance (MR) imaging of laboratory animals may require general anesthesia to minimize body movements over many hours. The anesthetization technique should allow physiologic parameters to remain as close to normal as possible, permit fast recovery, allow safe, repeated use, and avoid attachment of ferrous metal components to the animal. The purpose of this study was to evaluate an anesthetization technique that was developed to meet each of these qualifications.

An analysis of perceptual errors in reading mammograms using quasi-local spatial frequency spectra.

In this pilot study the authors examined areas on a mammogram that attracted the visual attention of experienced mammographers and mammography fellows, as well as areas that were reported to contain a malignant lesion, and, based on their spatial frequency spectrum, they characterized these areas by the type of decision outcome that they yielded: true-positives (TP), false-positives (FP), true-negatives (TN), and false-negatives (FN). Five 2-view (craniocaudal and medial-lateral oblique) mammogram cases were examined by 8 experienced observers, and the eye position of the observers was tracked. The observers were asked to report the location and nature of any malignant lesions present in the case.

Blinded review of retrospectively visible unreported breast cancers: an eye-position analysis.

Purpose: To determine whether unreported retrospectively identified cancers on mammograms receive prolonged visual attention and can be reliably detected in a blinded review.

Materials And Methods: Four experienced mammographers performed a blinded review of a test set of 20 retrospective cases where the cancer was not detected until the next mammographic evaluation, 10 prospective cases where the cancer was initially detected, and 10 cancer-free cases. Two views were digitized and displayed on a workstation.