Perception research in medical imaging

Use of eye tracking in medical education

Eye tracking has become increasingly applied in medical education research for studying the cognitive processes that occur during the performance of a task, such as image interpretation and surgical skills development. However, analysis and interpretation of the large amount of data obtained by eye tracking can be confusing. In this article, our intention is to clarify the analysis and interpretation of the data obtained from eye tracking. Understanding the relationship between eye tracking metrics (such as gaze, pupil and blink rate) and cognitive processes (such as visual attention, perception, memory and cognitive workload) is essential. The importance of calibration and how the limitations of eye tracking can be overcome is also highlighted.

Deep Learning Algorithm for Differentiating Patients with a Healthy Liver from Patients with Liver Lesions Based on MR Images

The problems in diagnosing the state of a vital organ such as the liver are complex and remain unresolved. These problems are underscored by frequently published studies on this issue. At the same time, demand for imaging diagnostics, preferably using a method that can detect the disease at the earliest possible stage, is constantly increasing. In this paper, we present liver diseases in the context of diagnosis, diagnostic problems, and possible elimination. We discuss the dataset and methods and present the stages of the pipeline we developed, leading to multiclass segmentation of the liver in multiparametric MR image into lesions and normal tissue. Finally, based on the processing results, each case is classified as either a healthy liver or a liver with lesions. For the training set, the AUC ROC is 0.925 (standard error 0.013 and a p-value less than 0.001), and for the test set, the AUC ROC is 0.852 (standard error 0.039 and a p-value less than 0.001). Further refinements to the proposed pipeline are also discussed. The proposed approach could be used in the detection of focal lesions in the liver and the description of liver tumors. Practical application of the developed multi-class segmentation method represents a key step toward standardizing the medical evaluation of focal lesions in the liver.

Early stage of radiological expertise modulates resting-state local coherence in the inferior temporal lobe

Background

The visual system and its inherent functions undergo experience-dependent changes through the lifespan, enabling acquisition of new skills. Previous fMRI studies using tasks reported increased specialization in a number of cortical regions subserving visual expertise. Although ample studies focused on representation of long-term visual expertise in the brain, i.e. in terms of year, monthly-based early-stage representation of visual expertise remains unstudied. Given that spontaneous neuronal oscillations actively encode previous experience, we propose brain representations in the resting state is fundamentally important.

Objective

The current study aimed to investigate how monthly-based early-stage visual expertise are represented in the resting state using the expertise model of radiologists.

Methods

In particular, we investigated the altered local clustering pattern of spontaneous brain activity using regional homogeneity (ReHo). A cohort group of radiology interns (n = 22) after one-month training in X-ray department and matched laypersons (n = 22) were recruited after rigorous behavioral assessment.

Results

The results showed higher ReHo in the right hippocampus (HIP) and the right ventral anterior temporal lobe (vATL) (corrected by Alphasim correction, P < 0.05). Moreover, ReHo in the right HIP correlated with the number of cases reviewed during intern radiologists' training (corrected by Alphasim correction, P < 0.05).

Conclusions

In sum, our results demonstrated that the early stage of visual expertise is more concerned with stabilizing visual feature and domain-specific knowledge into long-term memory. The results provided novel evidence regarding how early-stage visual expertise is represented in the resting brain, which help further elaborate how human visual expertise is acquired. We propose that our current study may provide novel ideas for developing new training protocols in medical schools.

Visual expertise modulates baseline brain activity: a preliminary resting-state fMRI study using expertise model of radiologists

Background

visual expertise and experience modulate evoked brain activity in response to training-related stimuli. However, few studies have considered how the visual experience is represented in the resting state brain activity. This study tried to investigate the way visual experience, i.e., visual recognition expertise, modulates baseline brain neuronal activity in the resting state using the model of radiologists.

Methods

The amplitude of low-frequency (< 0.08 Hz) fluctuation (ALFF) was used as the metric of baseline brain activity and a visual expertise model of radiologists to investigated this question. The visual recognition skill enables them to accurately identify pathological information in medical images. After the behavior measurement, a cohort group of radiology interns (n = 22) and a group of matched layperson (n = 22) were selected for inclusion in the study. The resting state functional magnetic resonance imaging (fMRI) scans were performed for all of the subjects.

Results

Higher ALFF in the right fusiform gyrus and the left orbitofrontal cortex were observed, and the ALFF in the fusiform gyrus was correlated with the intern radiologists’ behavioral expertise(all results corrected for multiple comparisons).

Conclusions

Visual experience modulates the baseline brain activity in both high-level visual cortex and high-order cognitive cortex, indicating the engagement of both top-down and bottom-up facilitation. We provide a novel perspective to how visual experience modulated cortical brain activity by introducing the resting state changes. Also, we propose that our current study may provide novel ideas for the development of new training protocols in medical school.

Intra- and Interobserver Agreement during the Assessment of the Different Stages of Root Development Using 4 Radiographic Classifications

INTRODUCTION

This study analyzed intra- and interobserver agreements during radiographic assessment of the different stages of root development using the dichotomous, Moorrees, Demirjian, and Cvek classifications, as well as the effect of the observer's level of experience on the result.

METHODS

Two hundred eighty-five digital periapical radiographs were examined via visual inspection by 3 experienced and 3 nonexperienced observers (n = 6) under strict technological and viewing conditions. After observer calibration, determination of the presence or absence of an open apex and the assignment of a root development stage according to the different subdivisions of the 4 indexes were performed. This evaluation was carried out by each observer in duplicate in the first round (n = 8) and repeated in the second round (n = 8). The 16 examinations performed by each observer (N = 96) were analyzed to determine the percentage of concordance followed by intraobserver, interobserver, and global observer agreement using the kappa coefficient and a weighted kappa. Additionally, to determine the level of concordance between the visual determination of an open or closed apex and the apical foramen width measured in millimeters, a dichotomized kappa coefficient was applied.

RESULTS

A good level of global observer agreement was found for the dichotomous, Demirjian, and Cvek classifications. However, a significantly low percentage of total concordance and global observer agreement (6.66% and 0.498, respectively) was obtained using the Moorrees classification, which was more pronounced among nonexperienced observers (0.247). Apical foramen width measurements indicated the presence of 143 roots with an open apex (50.2%) and 142 with a closed apex (49.8%), and the dichotomized kappa coefficient test revealed a good level of agreement during the visual determination of an open or closed apex (range, 0.611-0.636).

CONCLUSIONS

The classifications of Cvek and Demirjian provided reliable results when determining the different stages of root development. In contrast, the Moorrees classification provided the lowest agreement values, with a significant negative effect among nonexperienced observers. Finally, the visual estimation of the presence (or absence) of an open apex provided a good level of concordance with the radiographic apical foramen width.

Radiologists and Clinical Trials: Part 1 The Truth About Reader Disagreements

The debate over human visual perception and how medical images should be interpreted have persisted since X-rays were the only imaging technique available. Concerns over rates of disagreement between expert image readers are associated with much of the clinical research and at times driven by the belief that any image endpoint variability is problematic. The deeper understanding of the reasons, value, and risk of disagreement are somewhat siloed, leading, at times, to costly and risky approaches, especially in clinical trials. Although artificial intelligence promises some relief from mistakes, its routine application for assessing tumors within cancer trials is still an aspiration. Our consortium of international experts in medical imaging for drug development research, the Pharma Imaging Network for Therapeutics and Diagnostics (PINTAD), tapped the collective knowledge of its members to ground expectations, summarize common reasons for reader discordance, identify what factors can be controlled and which actions are likely to be effective in reducing discordance. Reinforced by an exhaustive literature review, our work defines the forces that shape reader variability. This review article aims to produce a singular authoritative resource outlining reader performance's practical realities within cancer trials, whether they occur within a clinical or an independent central review.

Interobserver variability in quality assessment of magnetic resonance images

Background

The perceptual quality of magnetic resonance (MR) images influences diagnosis and may compromise the treatment. The purpose of this study was to evaluate how the image quality changes influence the interobserver variability of their assessment.

Methods

For the variability evaluation, a dataset containing distorted MRI images was prepared and then assessed by 31 experienced medical professionals (radiologists). Differences between observers were analyzed using the Fleiss’ kappa. However, since the kappa evaluates the agreement among radiologists taking into account aggregated decisions, a typically employed criterion of the image quality assessment (IQA) performance was used to provide a more thorough analysis. The IQA performance of radiologists was evaluated by comparing the Spearman correlation coefficients, ρ, between individual scores with the mean opinion scores (MOS) composed of the subjective opinions of the remaining professionals.

Results

The experiments show that there is a significant agreement among radiologists (κ=0.12; 95% confidence interval [CI]: 0.118, 0.121; P<0.001) on the quality of the assessed images. The resulted κ is strongly affected by the subjectivity of the assigned scores, separately presenting close scores. Therefore, the ρ was used to identify poor performance cases and to confirm the consistency of the majority of collected scores (ρ_mean = 0.5706). The results for interns (ρ_mean = 0.6868) supports the finding that the quality assessment of MR images can be successfully taught.

Conclusions

The agreement observed among radiologists from different imaging centers confirms the subjectivity of the perception of MR images. It was shown that the image content and severity of distortions affect the IQA. Furthermore, the study highlights the importance of the psychosomatic condition of the observers and their attitude.

Serial dependence in a simulated clinical visual search task

In everyday life, we continuously search for and classify objects in the environment around us. This kind of visual search is extremely important when performed by radiologists in cancer image interpretation and officers in airport security screening. During these tasks, observers often examine large numbers of uncorrelated images (tumor x-rays, checkpoint x-rays, etc.) one after another. An underlying assumption of such tasks is that search and recognition are independent of our past experience. Here, we simulated a visual search task reminiscent of medical image search and found that shape classification performance was strongly impaired by recent visual experience, biasing classification errors 7% more towards the previous image content. This perceptual attraction exhibited the three main tuning characteristics of Continuity Fields: serial dependence extended over 12 seconds back in time (temporal tuning), it occurred only between similar tumor-like shapes (feature tuning), and only within a limited spatial region (spatial tuning). Taken together, these results demonstrate that serial dependence influences shape perception and occurs in visual search tasks. They also raise the possibility of a detrimental impact of serial dependence in clinical and practically relevant settings, such as medical image perception.

Investigating the effect of clinical history before electrocardiogram interpretation on the visual behavior and interpretation accuracy of clinicians

We examine the impact of the presentation of a patient's clinical history on subsequent visual appraisal and interpretation accuracy of electrocardiograms (ECGs). Healthcare-practitioners (N = 31) skilled in 12-lead ECG interpretation took part in a repeated-measures experiment with counterbalancing viewing 9 ECGs on a computer screen in two separate conditions: with/without an associated patient-history. A Hellinger-distance calculation was applied using a permutation test to eye-movement transitions at two granularity levels: between the ECG leads, and between smaller grid-cells, whose size was determined via data-driven clustering of the fixation points. Findings indicate that presentation of clinical-history does affect accuracy of interpretation in one ECG. Visual-behavior differed as a function of both history presentation and accuracy when considering transitions between the data-driven grid units (using a fine granularity, and able to show attention to parts of the waveform). Differences in visual-behavior at waveform level demonstrate an influence of patient-history and expertise that are not detected at the lead level. Visual-behaviour differs according to whether a patient-history is presented, and whether a clinician provides an accurate interpretation. This difference is evident in how the waveform itself is viewed, and is less present at the coarse granularity of visual transitions between leads. To understand how clinicians interpret ECGs, and potentially other medical images, visual transitions should be considered at a fine level of granularity, determined in a data-driven fashion.

Distractors in obstetric ultrasound: Do sonographers have safety concerns?

INTRODUCTION

Obstetric sonography is a highly skilled diagnostic medical examination. Pregnant women like to socialise their ultrasound experience with family, introducing distractions for the sonographer. Our objective was to survey ultrasound practitioners to identify concerns regarding interruptions and their opinions about socialisation during the examination.

METHODS

An online questionnaire was disseminated to study the views of Australian and New Zealand obstetric sonographers/sonologists. It was informed by a pilot study of possible distractors with quality and safety concerns and operator opinions regarding family bonding.

RESULTS

The opinions of 393 obstetric sonographers/sonologists informed our results. Distractors with the most negative aspects included disruptive children (93.3%) and mobile phone conversations (84.3%). Most respondents (62%) believed that a distractor only had to be present for 5 min or less to have an impact. Small children were identified by 87.5% of respondents as safety risks to themselves, to the patient and to sonographers. Sonographers were concerned that distractors caused a loss of concentration, interruption to a systematic scanning approach and increased false negatives in screening, missing important diagnoses. Sonographers strongly agreed that obstetric sonography facilitated maternal-fetal bonding, but only 15% thought that siblings bond with the fetus during the scan.

CONCLUSION

Obstetric sonographers in our study are concerned that distractors pose a negative impact on the quality and safety of ultrasound. They also recognise the importance of family bonding. Strategies to bridge the medical and social components of obstetric sonography should be developed to reduce quality and safety threats.

Influence of radiology expertise on the perception of nonmedical images

Identifying if participants with differing diagnostic accuracy and visual search behavior during radiologic tasks also differ in nonradiologic tasks is investigated. Four clinician groups with different radiologic experience were used: a reference expert group of five consultant radiologists, four radiology registrars, five senior house officers, and six interns. Each of the four clinician groups is known to have significantly different performance in the identification of pneumothoraces in chest x-ray. Each of the 20 participants was shown 6 nonradiologic images (3 maps and 3 sets of geometric shapes) and was asked to perform search tasks. Eye movements were recorded with a Tobii TX300 (Tobii Technology, Stockholm, Sweden) eye tracker. Four eye-tracking metrics were analyzed. Variables were compared to identify any differences among the groups. All data were compared by using nonparametric methods of analysis. The average number of targets identified in the maps did not change among groups [mean=5.8 of 6 targets (range 5.6 to 6 p=0.861)]. None of the four eye-tracking metrics investigated varied with experience in either search task (p>0.5). Despite clear differences in radiologic experience, these clinician groups showed no difference in nonradiologic search pattern behavior or skill across complex images. This is another viewpoint adding to the evidence that radiologic image interpretation is a learned skill and is task specific.

The Relative Impact of Ghosting and Noise on the Perceived Quality of MR Images

Magnetic resonance (MR) imaging is vulnerable to a variety of artifacts, which potentially degrade the perceived quality of MR images and, consequently, may cause inefficient and/or inaccurate diagnosis. In general, these artifacts can be classified as structured or unstructured depending on the correlation of the artifact with the original content. In addition, the artifact can be white or colored depending on the flatness of the frequency spectrum of the artifact. In current MR imaging applications, design choices allow one type of artifact to be traded off with another type of artifact. Hence, to support these design choices, the relative impact of structured versus unstructured or colored versus white artifacts on perceived image quality needs to be known. To this end, we conducted two subjective experiments. Clinical application specialists rated the quality of MR images, distorted with different types of artifacts at various levels of degradation. The results demonstrate that unstructured artifacts deteriorate quality less than structured artifacts, while colored artifacts preserve quality better than white artifacts.

Improving Patient Care Through Medical Image Perception Research

The interpretation of medical images across medical specialties is critical to patient care. As technology changes, so does health care, and clinicians today are increasingly viewing medical images in a variety of environments. Although access to such data is useful, even clinicians with expertise in image interpretation make errors. These errors may become more frequent as clinician workdays become longer and the number of images to be interpreted becomes larger. To prevent errors in medical image interpretation, we need to understand the underlying perceptual and cognitive mechanisms that guide image interpretation. We can then use what is learned to develop better training methods, automated image analysis, and processing tools. We can devise methods to reduce clinician fatigue and stress, and develop practice guidelines thereby improving patient care and outcomes.

Intraoperative radiography for evaluation of surgical miscounts

PURPOSE

Retained surgical items result in substantial morbidity, health care-related expense, and legal liability. This study determines the performance of a protocol for locating surgical items after a miscount, in which intraoperative radiography included a radiograph of the unaccounted for item.

METHODS

Institutional review board approval was obtained. In 20,820 operations performed between January 1, 2011 and April 1, 2013, a total of 183 consecutive surgical miscounts occurred, involving 180 patients (97 male, 83 female; median age: 55 years). Departmental protocol mandated that a radiograph of an example of the potentially retained item be taken simultaneously with each patient intraoperative radiograph. Three board-certified radiologists retrospectively reviewed these radiographs and follow-up imaging, achieving consensus on interpretation. Adherence to institutional protocol was assessed. Demographic data, surgical documentation, and clinical follow-up data were recorded.

RESULTS

The incidence of surgical miscounts was 0.9% (183 of 20,820). Only 9% (17 of 183) were resolved by discovery: outside the patient (8 cases); on intraoperative radiographs (5 cases); incidentally on follow-up radiographs (2 cases); and on retrospective review (2 cases). The false-negative rate was 44% (4 of 9). Neither of the 2 retained needles discovered postoperatively was removed. The procedures most prone to miscounts were: esophagogastrectomy (33%; 2 of 6); liver transplant (18%; 12 of 66); and Whipple procedure (16%; 7 of 44). Needles (65%) and sponges (9%) were the items that were overlooked most often. Adherence to the protocol of imaging an example of a potentially retained item was 91% (167 of 183).

CONCLUSIONS

Despite good adherence to a protocol of imaging the potentially retained items, small needles often were not visualized on intraoperative radiographs and were not subsequently removed, without known adverse events. This finding suggests that intraoperative radiography for small needles may be unnecessary, but further study is required.

Content-based image retrieval in radiology: analysis of variability in human perception of similarity

We aim to develop a better understanding of perception of similarity in focal computed tomography (CT) liver images to determine the feasibility of techniques for developing reference sets for training and validating content-based image retrieval systems. In an observer study, four radiologists and six nonradiologists assessed overall similarity and similarity in 5 image features in 136 pairs of focal CT liver lesions. We computed intra- and inter-reader agreements in these similarity ratings and viewed the distributions of the ratings. The readers' ratings of overall similarity and similarity in each feature primarily appeared to be bimodally distributed. Median Kappa scores for intra-reader agreement ranged from 0.57 to 0.86 in the five features and from 0.72 to 0.82 for overall similarity. Median Kappa scores for inter-reader agreement ranged from 0.24 to 0.58 in the five features and were 0.39 for overall similarity. There was no significant difference in agreement for radiologists and nonradiologists. Our results show that developing perceptual similarity reference standards is a complex task. Moderate to high inter-reader variability precludes ease of dividing up the workload of rating perceptual similarity among many readers, while low intra-reader variability may make it possible to acquire large volumes of data by asking readers to view image pairs over many sessions.

Adaptation aftereffects in the perception of radiological images

Radiologists must classify and interpret medical images on the basis of visual inspection. We examined how the perception of radiological scans might be affected by common processes of adaptation in the visual system. Adaptation selectively adjusts sensitivity to the properties of the stimulus in current view, inducing an aftereffect in the appearance of stimuli viewed subsequently. These perceptual changes have been found to affect many visual attributes, but whether they are relevant to medical image perception is not well understood. To examine this we tested whether aftereffects could be generated by the characteristic spatial structure of radiological scans, and whether this could bias their appearance along dimensions that are routinely used to classify them. Measurements were focused on the effects of adaptation to images of normal mammograms, and were tested in observers who were not radiologists. Tissue density in mammograms is evaluated visually and ranges from "dense" to "fatty." Arrays of images varying in intermediate levels between these categories were created by blending dense and fatty images with different weights. Observers first adapted by viewing image samples of dense or fatty tissue, and then judged the appearance of the intermediate images by using a texture matching task. This revealed pronounced perceptual aftereffects - prior exposure to dense images caused an intermediate image to appear more fatty and vice versa. Moreover, the appearance of the adapting images themselves changed with prolonged viewing, so that they became less distinctive as textures. These aftereffects could not be accounted for by the contrast differences or power spectra of the images, and instead tended to follow from the phase spectrum. Our results suggest that observers can selectively adapt to the properties of radiological images, and that this selectivity could strongly impact the perceived textural characteristics of the images.

Prioritization of brain MRI volumes using medical image perception model and tumor region segmentation

The objective of the present study is to explore prioritization methods in diagnostic imaging modalities to automatically determine the contents of medical images. In this paper, we propose an efficient prioritization of brain MRI. First, the visual perception of the radiologists is adapted to identify salient regions. Then this saliency information is used as an automatic label for accurate segmentation of brain lesion to determine the scientific value of that image. The qualitative and quantitative results prove that the rankings generated by the proposed method are closer to the rankings created by radiologists.

Sparseness of the trabecular pattern on dental radiographs: visual assessment compared with semi-automated measurements

OBJECTIVE

In diagnostic imaging; human perception is the most prominent, yet least studied, source of error. A better understanding of image perception will help to improve diagnostic performance. This study focuses on the perception of coarseness of trabecular patterns on dental radiographs. Comparison of human vision with machine vision should yield knowledge on human perception.

METHOD

In a study on identifying osteoporotic patients, dental radiographs were made from 505 post-menopausal women aged 45-70 years. Intra-oral radiographs of the lower and upper jaws were made. Five observers graded the trabecular pattern as dense, sparse or mixed. The five gradings were combined into a single averaged observer score per jaw. The radiographs were scanned and a region of interest (ROI) was indicated on each. The ROIs were processed with image analysis software measuring 25 image features. Pearson correlation and multiple linear regression were used to compare the averaged observer score with the image features.

RESULTS

14 image features correlated significantly with the observer judgement for both jaws. The strongest correlation was found for the average grey value in the ROI. Other features, describing that osteoporotic patients have fewer but bigger marrow spaces than controls, correlated less with the sparseness of the trabecular pattern than a rather crude measure for structure such as the average grey value.

CONCLUSION

Human perception of the sparseness of trabecular patterns is based more on average grey values of the ROI than on geometric details within the ROI.

Human-computer interaction in radiotherapy target volume delineation: a prospective, multi-institutional comparison of user input devices

The purpose of this study was the prospective comparison of objective and subjective effects of target volume region of interest (ROI) delineation using mouse-keyboard and pen-tablet user input devices (UIDs). The study was designed as a prospective test/retest sequence, with Wilcoxon signed rank test for matched-pair comparison. Twenty-one physician-observers contoured target volume ROIs on four standardized cases (representative of brain, prostate, lung, and head and neck malignancies) twice: once using QWERTY keyboard/scroll-wheel mouse UID and once with pen-tablet UID (DTX2100, Wacom Technology Corporation, Vancouver, WA, USA). Active task time, ROI manipulation task data, and subjective survey data were collected. One hundred twenty-nine target volume ROI sets were collected, with 62 paired pen-tablet/mouse-keyboard sessions. Active contouring time was reduced using the pen-tablet UID, with mean ± SD active contouring time of 26 ± 23 min, compared with 32 ± 25 with the mouse (p ≤ 0.01). Subjective estimation of time spent was also reduced from 31 ± 26 with mouse to 27 ± 22 min with the pen (p = 0.02). Task analysis showed ROI correction task reduction (p = 0.045) and decreased panning and scrolling tasks (p < 0.01) with the pen-tablet; drawing, window/level changes, and zoom commands were unchanged (p = n.s.) Volumetric analysis demonstrated no detectable differences in ROI volume nor intra- or inter-observer volumetric coverage. Fifty-two of 62 (84%) users preferred the tablet for each contouring task; 5 of 62 (8%) denoted no preference, and 5 of 62 (8%) chose the mouse interface. The pen-tablet UID reduced active contouring time and reduced correction of ROIs, without substantially altering ROI volume/coverage.

Development of subject-specific geometric spine model through use of automated active contour segmentation and kinematic constraint-limited registration

This paper describes the development of a patient-specific spine model through use of active contour segmentation and registration of intraoperative imaging of porcine vertebra augmented with kinematic constraints. The geometric active contours are fully automated and lead to a discrete representation of the image segmentation results. After determining errors within the segmentations, application of reliability theory allows the selection of active contour parameters to obtain best-fit segmentations from a stack of 2D images. The segmented images are then used in conjunction with C-arm fluoroscope images to simulate the result of intraoperative patient-specific model registration including patient and/or structure motion between preoperative and intraoperative scans. The results are validated through comparison of the error within the patient-specific model generated through use of the C-arm images with a model acquired directly from MRI images of the spine after motion. The results are applicable to the development of a wide variety of patient-specific geometric and biomechanical models.

[Efficacy of x-ray assessment in emergency surgical departments: an evaluation in a level I trauma center]

BACKGROUND

The aim of the study was to ascertain the state of the art in x-ray assessment in an emergency surgical department.

METHODS

From August 2008 to February 2009 a total of 1,588 plain x-rays of 658 patients from the emergency department were included in this study. The images were assessed by 3 experienced orthopedic surgeons and 1 experienced radiologist. The incidence of missed traumatic lesions and suspected lesions and the treatment of these patients were noted.

RESULTS

A total of 136 pathological cases with 238 pathological x-ray findings were found. The mean rate of missed lesions was 13% of the assessed cases. Despite the fact that the rate of missed lesions varied from 9-25% depending on the level of experience, all patients were treated adequately. The quality of x-ray assessment improved with the level of training of the individual doctors.

CONCLUSION

The present situation is in need of improvement but it is not critical. Junior medical staff should undergo a special training in x-ray assessment.

Current perspectives in medical image perception

Medical images constitute a core portion of the information a physician utilizes to render diagnostic and treatment decisions. At a fundamental level, this diagnostic process involves two basic processes: visually inspecting the image (visual perception) and rendering an interpretation (cognition). The likelihood of error in the interpretation of medical images is, unfortunately, not negligible. Errors do occur, and patients' lives are impacted, underscoring our need to understand how physicians interact with the information in an image during the interpretation process. With improved understanding, we can develop ways to further improve decision making and, thus, to improve patient care. The science of medical image perception is dedicated to understanding and improving the clinical interpretation process.

Diagnosis from fundus photographs

AIM

To investigate the way in which ophthalmologists observe fundi and make diagnoses from their observations.

METHODS

A set of 12 test photographs was presented to 9 ophthalmologists. The subjects were asked to identify the features in the photographs that are important for forming a diagnosis and were also asked to form differential diagnoses. The scanpaths of the subjects were recorded during their inspection of the photographs. Subsequently, they were asked to trace over the important features of four of the photographs.

RESULTS

The correctness of the diagnoses was described by weighted numerical scores. Differential diagnoses made after 30 s of inspection were significantly better than those made after 5 s. Irrespective of correctness, the reported diagnoses were dominated by the most obvious features of the photograph. Incorrect diagnoses were made either because the subjects failed to identify the significant features of the photograph or because they failed to comprehend the significance of the identified features.

CONCLUSION

Accurate funduscopy involves both perception of diagnostic features and cognitive interpretation of these features. Verbal reports, eye movement recordings and tracings reveal the features and interpretations used to make a diagnosis. These techniques will be used in a subsequent study to evaluate the relative contributions of formal training and experience to the development of diagnostic skills.

Breast screening: PERFORMS identifies key mammographic training needs

The UK Breast Screening Programme has recently expanded the age range for invitation in the prevalent round to 70 years. In contrast, fewer radiologists now choose to specialise in the area of breast cancer screening. In response to this depletion in film-reading personnel, an increasing number of radiographers have been trained as advanced practitioners in order to film-read alongside the current radiologists. As part of the quality assurance programme for the National Health Service Breast Screening Programme (NHSBSP), each film-reader can participate in a voluntary self-assessment scheme (Personal Performance in Mammographic Screening, PERFORMS) which consists of a number of recent challenging breast screening cases that are amassed nationally and distributed bi-annually. The scheme produces anonymous data on any areas of difficulties that individual participants have; these data can then be aggregated over groups of participants or over specific types of screening cases. In this paper, the areas of difficulty experienced by groups of advanced practitioners and radiologists on the PERFORMS cases were investigated to determine whether there were occupational group differences in reading skills in terms of case classification and feature type. Identifying if such problematic areas exist would be the first step to provide training sets specially tailored to the needs of particular occupational groups. As a bench mark for which cases could be problematic, the types of cases that a panel of experienced radiologists deemed as difficult was first examined in order to compare the performance of both film-reading groups against this panel standard. Secondly, any differences in performance error and case characteristics (classification, difficulty level and feature type) between radiologists and advanced practitioners were examined. The decisions of 15 experienced "panel" radiologists and approximately 400 film readers (including radiologists and advanced practitioners) were compared on 180 cases, over a number of years. This study employed a matched design which controlled for any differences between radiologists and advanced practitioners in terms of real-life factors, such as volume of cases read per week and years of radiological experience. The results elucidate the type of cases most appropriate for advanced mammographic training. No significant differences were found between the advanced practitioners and radiologists on these self-assessment screening cases, indicating that dedicated occupational group training is not required.