Understanding reasons for image rejection by radiologists and radiographers

INTRODUCTION

A core element of a radiographer's role is the decision on whether a radiograph is sufficient for diagnosis, or a repeat examination is needed. Studies illustrate the disagreement on the diagnostic value of radiographs between radiographers and radiologists, which may influence repeat examinations. This study investigates if parameters contributing to image quality are possible determinants to explain the difference between professions.

METHODS

A total of 74 radiographers and radiologists from three different countries assessed three data sets (chest PA, hip HBL, c-spine lateral), each containing 25 radiographs. All observers scored image quality in terms of anatomical visualisation, positioning, collimation, detector exposure and judged the diagnostic value using the ACR RadLex classification. All assessments were performed on a clinically relevant display. Visual grading characteristics were used to compare image quality evaluations between groups.

RESULTS

Radiographers scored the visualisation of anatomical structures lower than radiologists though the difference was not statistically significant. A difference in classification using the RadLex categories - with radiographers rejecting more radiographs - was demonstrated. Only the subjective evaluation of the detector exposure correlated statistically with RadLex ratings. There was no difference between radiographers and radiologists when reviewing patient positioning and collimation.

CONCLUSION

Radiographers and radiologists agree on the visualisation of anatomical structures, but radiographers are more critical towards the diagnostic value. Within the criteria studied, the evaluation of anatomical structures does not explain the difference. Radiographs have a higher change of being rejected if the observer (subjectively) assessed the detector exposure as inappropriate. This correlation is stronger for radiographers.

Osteoid Tumors of Bone

We present a review of several bone (osteoid)-forming tumors including enostosis, osteoid osteoma, osteoblastoma, and osteosarcoma. These entities were chosen because they are reasonably common-neither seen every day nor rare. When applicable, recent information about the lesions is included.

Chondroid Tumors of Bone

Recent scholarship on enchondroma, chondrosarcoma, and chondroblastoma is presented. The focus of this article is on the imaging appearance of these tumors and the means by which they can be distinguished from one another by both clinical and imaging criteria.

Gadolinium-based Contrast Agents Improve Detection of Recurrent Soft-Tissue Sarcoma at MRI

Purpose

To determine the diagnostic efficacy of gadolinium-based contrast agents for the detection of recurrent soft-tissue sarcoma compared with non-contrast-enhanced conventional MRI sequences.

Materials and Methods

A retrospective study of patients with soft-tissue sarcomas who were imaged from January 2009 to December 2014 was performed. MRI studies from 69 patients (mean age, 61 years ± 15 [standard deviation], 45 men) with recurrent soft-tissue sarcoma and 63 age-, sex-, and tumor-matched controls with positive findings (nonrecurrence) were presented to six musculoskeletal radiologists at a tertiary cancer center in three image groupings. Group 1 consisted of precontrast T1-weighted and fat-suppressed T2-weighted images (no contrast agent). Group 2 consisted of precontrast and postcontrast fat-saturated T1-weighted images. Group 3 consisted of precontrast and fat-saturated postcontrast T1- and fat-suppressed T2-weighted images. Images within these three groups contained either recurrent soft-tissue sarcomas or positive postoperative findings (nonsarcoma). The presentation order of the first two image sets was reversed for half the readers. The readers were asked to classify presence of tumor on a five-point scale. The average score from the readers was used as consensus score for each case, and a case was considered positive if the average score was less than 3. Receiver operating characteristic (ROC) analysis was performed using the average score for each image set.

Results

Assessment of the group 3 image set resulted in higher sensitivity (74%, 95% confidence interval [CI]: 62%, 83%) than the group 2 image set (64%, 95% CI: 51%, 75%), which was also more sensitive than the assessment of the group 1 images set (49%, 95% CI: 37%, 61%), with P = .02 for both. There was no significant difference in specificity between the three groups. The area under the ROC curve (AUC) for the assessment of group 1 was 0.78 (95% CI: 0.70, 0.86), which was significantly lower than that of group 2, 0.92 (95% CI: 0.87, 0.96) and group 3, 0.93 (95% CI: 0.88, 0.97), with P values of .0006 and < .0001, respectively. There was no difference between the AUCs of groups 2 and 3 (P = .58).

Conclusion

Gadolinium-based contrast agents improved diagnostic performance in detection of recurrent soft-tissue sarcoma. Addition of fat-saturated T2-weighted images provided modest improvement in sensitivity.Keywords: Efficacy Studies, MR-Contrast Agent, Oncology, Soft Tissues/Skin© RSNA, 2020.

Benign Osseous Tumors and Tumor-Like Conditions

We will provide an imaging-focused discussion of 3 benign bone tumors that do not fit in the categories of cartilaginous tumors or osteoid tumors. We have chosen giant cell tumor of bone, unicameral bone cyst, and fibrous dysplasia. All 3 of these entities are common enough that one does not have to be a musculoskeletal radiologist in a cancer hospital to encounter them occasionally, but none of them should be seen frequently.

Interpretation time for screening mammography as a function of the number of computer-aided detection marks

Purpose: Computer-aided detection (CAD) alerts radiologists to findings potentially associated with breast cancer but is notorious for creating false-positive marks. Although a previous paper found that radiologists took more time to interpret mammograms with more CAD marks, our impression was that this was not true in actual interpretation. We hypothesized that radiologists would selectively disregard these marks when present in larger numbers.

Approach: We performed a retrospective review of bilateral digital screening mammograms. We use a mixed linear regression model to assess the relationship between number of CAD marks and ln (interpretation time) after adjustment for covariates. Both readers and mammograms were treated as random sampling units.

Results: Ten radiologists, with median experience after residency of 12.5 years (range 6 to 24) interpreted 1832 mammograms. After accounting for number of images, Breast Imaging Reporting and Data System category, and breast density, the number of CAD marks was positively associated with longer interpretation time, with each additional CAD mark proportionally increasing median interpretation time by 4.35% for a typical reader.

Conclusions: We found no support for our hypothesis that radiologists will selectively disregard CAD marks when they are present in larger numbers.

Memory bias in observer-performance literature

The objective of our study was to determine how authors of published observer–performance experiments dealt with memory bias in study design. We searched American Journal of Roentgenology online and Radiology using “observer study” and “observer performance.” We included articles from 1970 or later that reported an observer performance experiment using human observers. We recorded the methods used by the authors to order presentation of the conditions being tested and images within sets for viewing. We recorded use and length of any time gap between viewings. We included 110 experiments. Forty-five used methods not subject to memory bias. Of 68 remaining experiments, 30 (44.1%) ordered the viewing of tested conditions to decrease memory bias. Fifteen (22.1%) ordered the tested conditions in ways that may create memory bias. Eleven (16.2%) intermixed the tested conditions. Forty-three (63.2%) used random or pseudorandom ordering of images within sets. Forty-six (67.6%) used a time gap (median 14 days) between viewings. Six (8.8%) did not use a time gap. Thirty-six (52.9%) did not indicate what methods they used in at least one studied parameter. Therefore, we conclude that 22.1% of the experiments could improve their methods of ordering tested conditions. Completeness of reporting could be improved by including more details regarding methods of ameliorating memory bias.

Consultation and citation rates for prior imaging studies and documents in radiology

Frequently, the consensus conclusion after quality assurance conferences in radiology is that whatever mistake was made could have been avoided if more prior images or documents had been consulted. It is generally assumed that anything that was not specifically cited in the report had not been consulted. Is it actually safe to assume that an image or document that is not cited was also not consulted? It is this question that this investigation addresses. In this Institutional Review Board-approved study, one observer watched the board-certified radiologists while they interpreted imaging studies and issued reports. He recorded what type of study was being interpreted [either computed tomography, magnetic resonance imaging, or conventional radiography (x-ray)]. He also recorded the number and type of prior imaging studies and documents that were consulted during the interpretation. These observations were then compared with the signed report to determine how many of the consulted imaging studies and documents were cited. Of the 198 previous imaging studies that the radiologists consulted, 116 (58.6%) were cited in a report. Of the 285 documents consulted, 3 (1.1%) were cited in a report. This difference in citation rate was statistically significant (p<0.0001). It cannot be safely assumed that an older radiologic image or medical document was not consulted during radiologic interpretation merely because it is not cited in the report. Radiologists often consult more old studies than they cite, and they do not cite the majority of prior documents that they consult.

18F-FDG PET/CT as an Indicator of Survival in Ewing Sarcoma of Bone

Objective: The existing literature of 18 F-FDG PET/CT in Ewing sarcoma investigates mixed populations of patients with both soft tissue and bone primary tumors. The aim of our study was to evaluate whether the maximum standardized uptake value (SUVmax) obtained with 18F-FDG PET/CT before and after induction chemotherapy can be used as an indicator of survival in patients with Ewing sarcoma originating exclusively in the skeleton.

Materials and Methods: A retrospective database search from 2004-2011 identified 28 patients who underwent 18 F-FDG PET/CT before (SUV1, n= 28) and after (SUV2, n=23) induction chemotherapy. Mean follow up was 3.3 years and median follow up for survivors was 6.3 years (range: 2.6-9.8 years). Multivariate and univariate Cox proportional hazard model was used to assess for correlation of SUV1, SUV2, and the change in SUVmax with overall survival (OS) and progression-free survival (PFS).

Results: Mean SUVmax was 10.74 before (SUV1) and after 4.11 (SUV2) induction chemotherapy. High SUV1 (HR = 1.05, 95% CI: 1.0-1.1, P = 0.01) and SUV2 (HR =1.2, 95% CI: 1.0-1.4, P = 0.01) were associated with worse OS. A cut off point of 11.6 was identified for SUV1. SUV1 higher than 11.6 had significantly worse OS (HR = 5.71, 95% CI: 1.85 - 17.61, P = 0.003) and PFS (HR = 3.16, 95% CI: 1.13 - 8.79, P = 0.03, P < 0.05 is significant).

Conclusion: 18F-FDG PET/CT can be used as a prognostic indicator for survival in primary Ewing sarcoma of bone.

Computational assessment of visual search strategies in volumetric medical images

When searching through volumetric images [e.g., computed tomography (CT)], radiologists appear to use two different search strategies: "drilling" (restrict eye movements to a small region of the image while quickly scrolling through slices), or "scanning" (search over large areas at a given depth before moving on to the next slice). To computationally identify the type of image information that is used in these two strategies, 23 naïve observers were instructed with either "drilling" or "scanning" when searching for target T's in 20 volumes of faux lung CTs. We computed saliency maps using both classical two-dimensional (2-D) saliency, and a three-dimensional (3-D) dynamic saliency that captures the characteristics of scrolling through slices. Comparing observers' gaze distributions with the saliency maps showed that search strategy alters the type of saliency that attracts fixations. Drillers' fixations aligned better with dynamic saliency and scanners with 2-D saliency. The computed saliency was greater for detected targets than for missed targets. Similar results were observed in data from 19 radiologists who searched five stacks of clinical chest CTs for lung nodules. Dynamic saliency may be superior to the 2-D saliency for detecting targets embedded in volumetric images, and thus "drilling" may be more efficient than "scanning."

Radiologists remember mountains better than radiographs, or do they?

Expertise with encoding material has been shown to aid long-term memory for that material. It is not clear how relevant this expertise is for image memorability (e.g., radiologists' memory for radiographs), and how robust over time. In two studies, we tested scene memory using a standard long-term memory paradigm. One compared the performance of radiologists to naïve observers on two image sets, chest radiographs and everyday scenes, and the other radiologists' memory with immediate as opposed to delayed recognition tests using musculoskeletal radiographs and forest scenes. Radiologists' memory was better than novices for images of expertise but no different for everyday scenes. With the heterogeneity of image sets equated, radiologists' expertise with radiographs afforded them better memory for the musculoskeletal radiographs than forest scenes. Enhanced memory for images of expertise disappeared over time, resulting in chance level performance for both image sets after weeks of delay. Expertise with the material is important for visual memorability but not to the same extent as idiosyncratic detail and variability of the image set. Similar memory decline with time for images of expertise as for everyday scenes further suggests that extended familiarity with an image is not a robust factor for visual memorability.

Skeletal Muscle Metastasis from Renal Cell Carcinoma: 21 cases and review of the literature

OBJECTIVES

This study aimed to raise radiologists' awareness of skeletal muscle metastases (SMM) in renal cell carcinoma (RCC) cases and to clarify their imaging appearance.

METHODS

A retrospective analysis was undertaken of 21 patients between 44-75 years old with 72 SMM treated from January 1990 to May 2009 at the MD Anderson Cancer Center in Houston, Texas, USA. Additionally, 37 patients with 44 SMM from a literature review were analysed.

RESULTS

Among the 21 patients, the majority of SMM were asymptomatic and detected via computed tomography (CT). Mean metastasis size was 18.3 mm and the most common site was the trunk muscles (83.3%). The interval between discovery of the primary tumour and metastasis detection ranged up to 234 months. Peripheral enhancement (47.1%) was the most common post-contrast CT pattern and non-contrasted CT lesions were often isodense. Magnetic resonance imaging (MRI) characteristics were varied. Five lesions with available T1-weighted pre-contrast images were hyperintense to the surrounding muscle. Other organ metastases were present in 20 patients. Of the 44 SMM reported in the literature, the majority were symptomatic. Average metastasis size was 53.4 mm and only 20.5% of SMM were in trunk muscles. The average interval between tumour discovery and metastasis detection was 101 months. Other organ metastases were recorded in 17 out of 29 patients.

CONCLUSION

SMM should always be considered in patients with RCC, even well after primary treatment. SMM from RCC may be invisible on CT without intravenous contrast; contrast-enhanced studies are therefore recommended. SMM are often hyperintense to the surrounding muscle on T1-weighted MRI scans.

Radiologist experience effects on contrast detection

Current literature shows that radiologist experience does not affect detection tasks when the object does not require medical training to detect. However, the research was never sufficiently detailed to examine if the contrast detection threshold is also the same for radiologists versus nonradiologists. Previously, contrast threshold research was performed predominantly on nonradiologists. Therefore, any differences could lead to over- or under-estimation of the performance capabilities of radiologists. Fourteen readers, evenly divided between radiologists and nonradiologists, read a set of 150 mammogram-like images. The study was performed with the location of the objects known and unknown, requiring two separate readings. No difference in the contrast detection threshold between reader groups for either the location-unknown (4.9 just noticeable differences) or location-known (3.3 just noticeable differences) images was seen. The standard deviation for the location-unknown condition had no difference (p 0.91). But for the location-known condition, a significant difference (p 0.0009) was seen between radiologists and nonradiologists. No difference in contrast detection based on reader experience was observed, but decreased variance was seen with radiologists in the location-known condition.

Consistency of response and image recognition, pulmonary nodules

OBJECTIVE

To investigate the effect of recognition of a previously encountered radiograph on consistency of response in localized pulmonary nodules.

METHODS

13 radiologists interpreted 40 radiographs each to locate pulmonary nodules. A few days later, they again interpreted 40 radiographs. Half of the images in the second set were new. We asked the radiologists whether each image had been in the first set. We used Fisher's exact test and Kruskal-Wallis test to evaluate the correlation between recognition of an image and consistency in its interpretation. We evaluated the data using all possible recognition levels-definitely, probably or possibly included vs definitely, probably or possibly not included by collapsing the recognition levels into two and by eliminating the "possibly included" and "possibly not included" scores.

RESULTS

With all but one of six methods of looking at the data, there was no significant correlation between consistency in interpretation and recognition of the image. When the possibly included and possibly not included scores were eliminated, there was a borderline statistical significance (p = 0.04) with slightly greater consistency in interpretation of recognized than that of non-recognized images.

CONCLUSION

We found no convincing evidence that radiologists' recognition of images in an observer performance study affects their interpretation on a second encounter.

ADVANCES IN KNOWLEDGE

Conscious recognition of chest radiographs did not result in a greater degree of consistency in the tested interpretation than that in the interpretation of images that were not recognized.

Differentiation of Benign Fluid Collections from Soft-Tissue Sarcomas on FDG-PET/CT

OBJECTIVE

To assess the diagnostic performance of (18)F-FDG PET-CT in differentiating soft tissue sarcomas (STSs) from benign fluid collections (BFs).

MATERIALS AND METHODS

Four readers independently reviewed 100 lesions on (18)F-FDG PET-CT and subjectively classified each lesion as an STS or BF and scored the spatial pattern of (18)F-FDG avidity (SP) of each on a 4-point ordered scale (thin, moderate, thick, solid).

RESULTS

Subjective assessment by readers allowed sensitive (91%-98%) differentiation of STSs from BFs, with lower specificity (59%-91%). The STSs had significantly higher SUVmax (median 10.7, range: 2.0-33.7) than BFs (median 2.8, range: 1.1-12.3). Reader agreement in assessment of SP had average κ = 0.61 (range 0.46-0.70). Classification of thick or solid SP as STS yielded an inter-reader averaged sensitivity and specificity of 69% and 98%, respectively. The presence of thick or solid SP resulted in 14.1-fold increase in partial odds of STS. Each unit increase in SUVmax resulted in 1.35-fold increase in partial odds of STS. The receiver operating characteristic (ROC) curves and 95% intervals for SUVmax alone and SUVmax + SP overlapped. The average subjective assessments for the four readers and estimated performance of using SP alone were both contained within the 95% intervals of the two ROC curves.

CONCLUSIONS

(18)F-FDG PET-CT is a sensitive modality for differentiating STSs from BFs. SUVmax and SP are significantly associated with STS. Classification schemes based upon SUVmax alone or augmented with SP can be useful for distinguishing STS from BF.

Memory for previously viewed radiographs and the effect of prior knowledge of memory task

RATIONALE AND OBJECTIVES

To investigate the effect of being forewarned that they would be asked to identify repeated images on radiologists' recognition of previously interpreted versus new chest radiographs.

MATERIALS AND METHODS

Thirteen radiologists viewed 60 posterior-anterior chest radiographs, 31 with and 29 without nodules, in two sets of 40 images each. Eight radiologists were forewarned and five radiologists were not forewarned of the memory task. Twenty images in each of the two sets were unique to each set and 20 images occurred in both sets. The readers indicated the presence or absence of any nodules during both readings, and in the second reading session they also indicated whether they thought each image had also occurred in the first reading.

RESULTS

There was no significant difference in recognition memory performance between forewarned and not-forewarned readers. Overall accuracy in distinguishing previously-viewed from new images was 60.7%.

CONCLUSIONS

Being forewarned of the memory task did not improve recognition memory.

Stereoscopic interpretation of low-dose breast tomosynthesis projection images

The purpose of this study was to evaluate stereoscopic perception of low-dose breast tomosynthesis projection images. In this Institutional Review Board exempt study, craniocaudal breast tomosynthesis cases (N = 47), consisting of 23 biopsy-proven malignant mass cases and 24 normal cases, were retrospectively reviewed. A stereoscopic pair comprised of two projection images that were ±4° apart from the zero angle projection was displayed on a Planar PL2010M stereoscopic display (Planar Systems, Inc., Beaverton, OR, USA). An experienced breast imager verified the truth for each case stereoscopically. A two-phase blinded observer study was conducted. In the first phase, two experienced breast imagers rated their ability to perceive 3D information using a scale of 1-3 and described the most suspicious lesion using the BI-RADS® descriptors. In the second phase, four experienced breast imagers were asked to make a binary decision on whether they saw a mass for which they would initiate a diagnostic workup or not and also report the location of the mass and provide a confidence score in the range of 0-100. The sensitivity and the specificity of the lesion detection task were evaluated. The results from our study suggest that radiologists who can perceive stereo can reliably interpret breast tomosynthesis projection images using stereoscopic viewing.

Trend of contrast detection threshold with and without localization

Published information on contrast detection threshold is based primarily on research using a location-known methodology. In previous work on testing the Digital Imaging and Communications in Medicine (DICOM) Grayscale Standard Display Function (GSDF) for perceptual linearity, this research group used a location-unknown methodology to more closely reflect clinical practice. A high false-positive rate resulted in a high variance leading to the conclusion that the impact on results of employing a location-known methodology needed to be explored. Fourteen readers reviewed two sets of simulated mammographic background images, one with the location-unknown and one with the location-known methodology. The results of the reader study were analyzed using Reader Operating Characteristic (ROC) methodology and a paired t test. Contrast detection threshold was analyzed using contingency tables. No statistically significant difference was found in GSDF testing, but a highly statistical significant difference (p value <0.0001) was seen in the ROC (AUC) curve between the location-unknown and the location-known methodologies. Location-known methodology not only improved the power of the GSDF test but also affected the contrast detection threshold which changed from +3 when the location was unknown to +2 gray levels for the location-known images. The selection of location known versus unknown in experimental design must be carefully considered to ensure that the conclusions of the experiment reflect the study's objectives.

On the choice of acceptance radius in free-response observer performance studies

OBJECTIVES

Choosing an acceptance radius or proximity criterion is necessary to analyse free-response receiver operating characteristic (FROC) observer performance data. This is currently subjective, with little guidance in the literature about what is an appropriate acceptance radius. We evaluated varying acceptance radii in a nodule detection task in chest radiography and suggest guidelines for determining an acceptance radius.

METHODS

80 chest radiographs were chosen, half of which contained nodules. We determined each nodule's centre. 21 radiologists read the images. We created acceptance radii bins of <5 pixels, <10 pixels, <20 pixels and onwards up to <200 and 200+ pixels. We counted lesion localisations in each bin and visually compared marks with the borders of nodules.

RESULTS

Most reader marks were tightly clustered around nodule centres, with tighter clustering for smaller than for larger nodules. At least 70% of readers' marks were placed within <10 pixels for small nodules, <20 pixels for medium nodules and <30 pixels for large nodules. Of 72 inspected marks that were less than 50 pixels from the centre of a nodule, only 1 fell outside the border of a nodule.

CONCLUSION

The acceptance radius should be based on the larger nodule sizes. For our data, an acceptance radius of 50 pixels would have captured all but 2 reader marks within the borders of a nodule, while excluding only 1 true-positive mark. The choice of an acceptance radius for FROC analysis of observer performance studies should be based on the size of larger abnormalities.

Quantifying the clinical relevance of a laboratory observer performance paradigm

OBJECTIVE

Laboratory observer performance measurements, receiver operating characteristic (ROC) and free-response ROC (FROC) differ from actual clinical interpretations in several respects, which could compromise their clinical relevance. The objective of this study was to develop a method for quantifying the clinical relevance of a laboratory paradigm and apply it to compare the ROC and FROC paradigms in a nodule detection task.

METHODS

The original prospective interpretations of 80 digital chest radiographs were classified by the truth panel as correct (C=1) or incorrect (C=0), depending on correlation with additional imaging, and the average of C was interpreted as the clinical figure of merit. FROC data were acquired for 21 radiologists and ROC data were inferred using the highest ratings. The areas under the ROC and alternative FROC curves were used as laboratory figures of merit. Bootstrap analysis was conducted to estimate conventional agreement measures between laboratory and clinical figures of merit. Also computed was a pseudovalue-based image-level correctness measure of the laboratory interpretations, whose association with C as measured by the area (rAUC) under an appropriately defined relevance ROC curve, is as a measure of the clinical relevance of a laboratory paradigm.

RESULTS

Low correlations (e.g. κ=0.244) and near chance level rAUC values (e.g. 0.598), attributable to differences between the clinical and laboratory paradigms, were observed. The absolute width of the confidence interval was 0.38 for the interparadigm differences of the conventional measures and 0.14 for the difference of the rAUCs.

CONCLUSION

The rAUC measure was consistent with the traditional measures but was more sensitive to the differences in clinical relevance. A new relevance ROC method for quantifying the clinical relevance of a laboratory paradigm is proposed.

Snakules: a model-based active contour algorithm for the annotation of spicules on mammography

We have developed a novel, model-based active contour algorithm, termed "snakules", for the annotation of spicules on mammography. At each suspect spiculated mass location that has been identified by either a radiologist or a computer-aided detection (CADe) algorithm, we deploy snakules that are converging open-ended active contours also known as snakes. The set of convergent snakules have the ability to deform, grow and adapt to the true spicules in the image, by an attractive process of curve evolution and motion that optimizes the local matching energy. Starting from a natural set of automatically detected candidate points, snakules are deployed in the region around a suspect spiculated mass location. Statistics of prior physical measurements of spiculated masses on mammography are used in the process of detecting the set of candidate points. Observer studies with experienced radiologists to evaluate the performance of snakules demonstrate the potential of the algorithm as an image analysis technique to improve the specificity of CADe algorithms and as a CADe prompting tool.

Conspicuity of microcalcifications on digital screening mammograms using varying degrees of monitor zooming

RATIONALE AND OBJECTIVES

American College of Radiology guidelines suggest that digital screening mammographic images should be viewed at the full resolution at which they were acquired. This slows interpretation speed. The aim of this study was to examine the effect of various levels of zooming on the detection and conspicuity of microcalcifications.

MATERIALS AND METHODS

Six radiologists viewed 40 mammographic images five times in different random orders using five different levels of zooming: full resolution (100%) and 30%, 61%, 88%, and 126% of that size. Thirty-three images contained microcalcifications varying in subtlety, all associated with breast cancer. The clusters were circled. Seven images contained no malignant calcifications but also had randomly placed circles. The radiologists graded the presence or absence and visual conspicuity of any calcifications compared to calcifications in a reference image. They also counted the microcalcifications.

RESULTS

The radiologists saw the microcalcifications in 94% of the images at 30% size and in either 99% or 100% of the other tested levels of zooming. Conspicuity ratings were worst for the 30% size and fairly similar for the others. Using the 30% size, two radiologists failed to see the microcalcifications on either the craniocaudal or mediolateral oblique view taken from one patient. Interobserver agreement regarding the number of calcifications was lowest for the 30% images and second lowest for the 100% images.

CONCLUSIONS

Images at 30% size should not be relied on alone for systematic scanning for microcalcifications. The other four levels of magnification all performed well enough to warrant further testing.

Why does it take longer to read digital than film-screen screening mammograms? A partial explanation

Digital screening mammograms (DM) take longer to interpret than film-screen screening mammograms (FSM). We evaluated what part of the process takes long in our reading environment. We selected cases from those for which timed readings had been performed as part of a previous study. Readers were timed as they performed various computer manipulations on groups of DM cases and as they moved the alternator and adjusted lighting and manual shutters for FSM cases. Subtracting manipulation time from the original interpretation times yielded estimated times to reach a decision. Manipulation times for DM ranged from a low of 11 s when four-view DM were simply opened and closed in a 4-on-1 hanging protocol before moving on to the next study to 113.8 s when each view of six-view DM were brought up 1-on-1, enlarged to 100% resolution, and panned through. Manipulation times for groups of FSM ranged from 8.3 to 12.1 s. Estimated decision-making times for DM ranged from 128.0 to 202.2 s, while estimated decision-making time for FSM ranged from 60.9 to 146.3 s. Computer manipulation time partially explains the discrepancy in interaction times between DM and FSM. Radiologists also appear to spend more time looking at DM than at FSM before making a decision.

Results of a survey on digital screening mammography: prevalence, efficiency, and use of ancillary diagnostic AIDS

OBJECTIVE

As the use of full-field digital screening mammography grows rapidly, this study was conducted to determine the time required to interpret digital soft-copy (filmless) mammography compared with conventional film-screen screening mammography and to evaluate radiologists' use of ancillary diagnostic aids when interpreting digital mammography (DM) and conventional film-screen mammography (FSM).

MATERIALS AND METHODS

An 18-question survey was sent to 1,703 members of the Society of Breast Imaging, whose e-mail addresses were provided by the society. After subtracting those from whom out-of-office e-mail responses were received and three who wrote back to exclude themselves, there were 1,659 potential participants. Data from the respondents were collected and analyzed by tabulation and cross-tabulation.

RESULTS

In total, 396 members of the Society of Breast Imaging completed and returned surveys, for a 23.9% response rate. Of the respondents, 49.0% said that they had access to and interpreted DM. Their estimated average time to read a single digital mammographic study was 2.6 minutes, compared with 2.0 minutes for reading a single film-screen mammographic study. Therefore, the perceived time difference was 0.6 minutes. Magnification was the main ancillary diagnostic aid used in interpreting both DM and FSM: 74.2% of respondents used computer-based magnification at least half the time in interpreting DM, and 90.9% used optical magnification at least half the time in interpreting FSM. Optical magnification was also used by 28.5% of respondents at least half the time in interpreting DM. The respondents also used computer-aided detection frequently: 91.0% and 76.3% of those who had computer-aided detection available said that they used it at least 75% of the time in interpreting DM and FSM, respectively.

CONCLUSION

Digital mammography takes longer to interpret than FSM. Radiologists use various ancillary diagnostic aids, but magnification and computer-aided detection are the two most commonly used aids.

Article Commentary: Computer-Aided Detection of Breast Cancer — Have All Bases Been Covered?

The use of computer-aided detection (CAD) systems in mammography has been the subject of intense research for many years. These systems have been developed with the aim of helping radiologists to detect signs of breast cancer. However, the effectiveness of CAD systems in practice has sparked recent debate. In this commentary, we argue that computer-aided detection will become an increasingly important tool for radiologists in the early detection of breast cancer, but there are some important issues that need to be given greater focus in designing CAD systems if they are to reach their full potential.

Computed tomographic evaluation of calcaneal fractures

Computed tomography (CT) can be a useful adjunct to conventional radiographs in the evaluation and treatment planning of comminuted calcaneal fractures. Either a combination of direct coronal and axial scan planes or a single set of oblique images may be used to study the calcaneus. CT can show the fracture planes, including the amount of displacement of fracture lines entering the posterior subtalar facet and the relationship of the sustentaculum tali to the remainder of the bone. Evaluation of the calcaneocuboid joint and any widening that has occurred due to the fracture is also easily accomplished with CT. CT should be interpreted in conjunction with the conventional radiographs as rotational components and flattening of the Böhler angle may be appreciated better on them than on CT.

Magnetic resonance imaging of the musculoskeletal system: part 7. The ankle

Diagnosis of many traumatic or attritional lesions about the ankle may be difficult with only the history, physical examination, and conventional radiographs. When uncertainty is present clinically or when precise depiction of the extent of injury will assist with treatment planning, magnetic resonance imaging may be a useful adjunct to these basic methods of evaluation. In particular, magnetic resonance imaging is useful for the identification and evaluation of tendinitis, tendon dislocations, osteochondral lesions, and occult fractures. Additional clinical settings in which magnetic resonance imaging may be helpful include evaluation of tumors, osteomyelitis, and tarsal coalition.

Pelvic insufficiency fractures associated with radiation atrophy: clinical recognition and diagnostic evaluation

Pelvic bone injuries are infrequent complications of radiotherapy. However, insufficiency fractures in irradiated pelvic bones may be underdetected, particularly in postmenopausal women. We describe the clinical presentation, radiologic evaluation, and course of disease in three patients with postradiation pelvic insufficiency fractures. Differential diagnosis included metastatic disease, tumor recurrence, and second malignancy. Recognition of radiographic features may prevent unnecessary, possibly morbid treatments.

Low-grade chondrosarcoma in a 12-year-old boy

We present a case of a rare central chondrosarcoma in a 12-year-old boy and discuss its radiographic and magnetic resonance appearance.

Categorization of acromial shape: interobserver variability with MR imaging and conventional radiography

OBJECTIVE

Our purpose was to determine interobserver variability in the interpretation of the shape of the acromion on sagittal oblique MR images and conventional radiographs. The shape of the acromion was defined according to a previously described classification scheme.

MATERIALS AND METHODS

We reviewed 26 sets of sagittal oblique MR images and corresponding conventional Y- or outlet-view radiographs of the shoulder. The shape of the acromion was graded for each study independently by four reviewers. Interobserver agreement was measured by using the kappa statistic. Analysis of variance and the chi 2-test were used for univariate analysis.

RESULTS

The acromion was interpreted most often as being curved. The observers scored 9% of MR images and 28% of conventional radiographs as nondiagnostic (p < .001) (41% of transscapular Y views and 3% of supraspinatus outlet views were also considered nondiagnostic [p < .0001]). Kappa values were .23 for MR images and .43 for conventional radiographs. Variability in interpretation between techniques when controlled for observer was not statistically significant.

CONCLUSION

Although sagittal oblique MR images were significantly more likely than conventional radiographs to be considered diagnostic by observers, interobserver agreement for MR examinations was poor. There was moderate agreement with conventional radiographs. This calls into question the usefulness of the previous system of interpretation and suggests that it might be more applicable with conventional radiographs than with MR images.

Radiographic findings of extremity tuberculosis in childhood: back to the future?

Since 1985, there has been an increase in the incidence of skeletal tuberculosis. Although this recent increase may prove to be temporary, familiarity with the protein manifestations of the disease is essential. The authors studied radiographs of 45 children in whom tuberculosis of the extremities had been diagnosed between 1937 and July 1991. Disease involved the hip in 18 cases; the knee in 17; the ankle in five; the shoulder in two; the midfoot in two; and the elbow, wrist, and hands in one each. Radiographic findings included joint effusion, periarticular osteopenia, joint space narrowing, cortical irregularity, lytic lesions, periosteal new bone formation, and advanced epiphyseal maturity. When the hip was involved, subluxation was a common finding. There is no single pathognomonic finding with which to make the diagnosis of skeletal tuberculosis. Clinical information may be helpful.

Magnetic resonance imaging of the postoperative shoulder

The use of MR imaging in the evaluation of the postoperative shoulder and the findings indicative of postoperative pathology remain largely unexplored. MR imaging does seem to be diagnostic of complete rotator cuff tears following cuff repair. In all postoperative cases, a key to differentiating the expected from the pathologic is to be familiar with the procedure that was performed.

A simple and effective postangiographic femoral artery pressure dressing

We describe a simple, inexpensive pressure dressing which supplements manual pressure and may be applied quickly and easily following femoral arterial puncture for angiography. This technique has been used on several thousand patients without complications.