Characterization of diffraction-enhanced imaging contrast in breast cancer

Diffraction-enhanced imaging (DEI) is a new x-ray imaging modality that has been shown to enhance contrast between normal and cancerous breast tissues. In this study, diffraction-enhanced imaging in computed tomography (DEI-CT) mode was used to quantitatively characterize the refraction contrasts of the organized structures associated with invasive human breast cancer. Using a high-sensitivity Si (3 3 3) reflection, the individual features of breast cancer, including masses, calcifications and spiculations, were observed. DEI-CT yields 14, 5 and 7 times higher CT numbers and 10, 9 and 6 times higher signal-to-noise ratios (SNR) for masses, calcifications and spiculations, respectively, as compared to conventional CT of the same specimen performed using the same detector, x-ray energy and dose. Furthermore, DEI-CT at ten times lower dose yields better SNR than conventional CT. In light of the recent development of a compact DEI prototype using an x-ray tube as its source, these results, acquired at a clinically relevant x-ray energy for which a pre-clinical DEI prototype currently exists, suggest the potential of clinical implementation of mammography with DEI-CT to provide high-contrast, high-resolution images of breast cancer (Parham 2006 PhD Dissertation University of North Carolina at Chapel Hill).

Comparison of MRI endpoints for assessing breast cancer response to neoadjuvant treatment: preliminary findings of the American College of Radiology Imaging Network (ACRIN) trial 6657

Abstract #6043

Background: ACRIN 6657, the imaging component of the I-SPY trial (CALGB 150007/150012), is a multi-center study testing the ability of MRI to provide in-vivo quantification of breast tumor response to neoadjuvant chemotherapy, for early prediction of response and stratification of risk-of-recurrence following treatment. We report results from preliminary analysis comparing MRI variables for correlation with pathologic response and disease progression. Methods: Women with ≥3 cm invasive breast cancer receiving an anthracycline-cyclophosphamide (AC) neoadjuvant chemotherapy regimen followed by a taxane (T) were enrolled between May 2002 and March 2006. Contrast-enhanced MRI was performed prior to start of treatment (baseline), following 1 cycle of AC chemotherapy (t2), between AC and T regimens (t3), and after all chemotherapy but prior to surgery (t4). MRI assessments included tumor longest diameter (MRLD), tumor volume (MRVol), and signal enhancement ratio (SER), a measure of contrast enhancement kinetics. Clinical size (cSize) and mammographic longest diameter (MGLD) were also recorded. Linear dimension was measured by the radiologist for MGLD and MRLD; MRVol was calculated by computer using SER thresholds. Pathologic residual disease size (pSize) and residual cancer burden (RCB) index were evaluated following surgery. Results: 237 patients were enrolled at 9 institutions. 216 patients with complete imaging formed the preliminary analysis set. At time of analysis 42 patients had progressed or died with mean time-to-progression of 21 months; 174 patients were progression-free with mean follow-up time of 42 months. At t4, MRVol was more strongly correlated with pSize than MRLD, SER or cSize (r=.61 vs .28, .24 and .43), while SER showed a stronger correlation with RCB than MRLD, MRVol or cSize (r = .45 vs .30, .31 and .37). MGLD at t4 did not show a significant correlation with either pSize or RCB. Early measurements of tumor size change from baseline by MRVol at t2, and MRVol, MRLD and SER at t3, all showed significant correlation with RCB. In univariate logistic regressions, all t4 measurements were found to be predictive of disease progression. Conclusion: Among clinical and imaging measurements of residual breast tumor size, MRI appears to most accurately reflect pathologic extent of disease following neoadjuvant treatment. Preliminary findings also suggest that tumor size and contrast kinetics measured by MRI may be useful early predictors of treatment response. ACRIN 6657 is continuing to collect follow-up data toward the primary aim testing MRI for stratification of post-treatment risk groups according to 3-year disease-free survival. This work is funded by NIH/ACRIN Grant U01 CA79778S2, CALGB Grants CA31946 and CA33601, and NCI SPORE Grant CA58207.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6043.

Mass density images from the diffraction enhanced imaging technique

Conventional x-ray radiography measures the projected x-ray attenuation of an object. It requires attenuation differences to obtain contrast of embedded features. In general, the best absorption contrast is obtained at x-ray energies where the absorption is high, meaning a high absorbed dose. Diffraction-enhanced imaging (DEI) derives contrast from absorption, refraction, and extinction. The refraction angle image of DEI visualizes the spatial gradient of the projected electron density of the object. The projected electron density often correlates well with the projected mass density and projected absorption in soft-tissue imaging, yet the mass density is not an "energy"-dependent property of the object, as is the case of absorption. This simple difference can lead to imaging with less x-ray exposure or dose. In addition, the mass density image can be directly compared (i.e., a signal-to-noise comparison) with conventional radiography. We present the method of obtaining the mass density image, the results of experiments in which comparisons are made with radiography, and an application of the method to breast cancer imaging.

Improving the detection of simulated masses in mammograms through two different image-processing techniques

RATIONALE AND OBJECTIVES

The purpose of this study was to determine whether contrast-limited adaptive histogram equalization (CLAHE) or histogram-based intensity windowing (HIW) improves the detection of simulated masses in dense mammograms.

MATERIALS AND METHODS

Simulated masses were embedded in portions of mammograms of patients with dense breasts; the mammograms were digitized at 50 microm per pixel, 12 bits deep. In two different experiments, images were printed both with no processing applied and with related parameter settings of two image-processing methods. A simulated mass was embedded in a realistic background of dense breast tissue, with its position varied. The key variables in each trial included the position of the mass, the contrast levels of the mass relative to the background, and the selected parameter settings for the image-processing method.

RESULTS

The success in detecting simulated masses on mammograms with dense backgrounds depended on the parameter settings of the algorithms used. The best HIW setting performed better than the best fixed-intensity window setting and better than no processing. Performance with the best CLAHE settings was no different from that with no processing. In the HIW experiment, there were no significant differences in observer performance between processing conditions for radiologists and nonradiologists.

CONCLUSION

HIW should be tested in clinical images to determine whether the detection of masses by radiologists can be improved. CLAHE processing will probably not improve the detection of masses on clinical mammograms.

Factors affecting phantom scores at annual mammography facility inspections by the U.S. Food and Drug Administration

RATIONALE AND OBJECTIVES

The authors performed this study to evaluate the factors affecting phantom image score at the annual inspection of mammography facilities.

MATERIALS AND METHODS

In 1997, three U.S. Food and Drug Administration (FDA)-trained inspectors performed inspections of all mammography facilities in North Carolina. All federal and state inspection data were collected and evaluated by using linear regression analysis. Factors affecting the American College of Radiology phantom scores were assessed.

RESULTS

Phantom score was affected by inspector identity, view box luminance, and optical density. All of these factors had a statistically significant effect on mass score (P < .05). Inspector identity yielded a statistically significant effect on speck group score, fibril score, and total score. Luminance yielded a statistically significant effect on both speck group score and total score.

CONCLUSION

Phantom scoring should be automated to allow for more consistent interobserver scoring. In addition, radiology facilities can improve the likelihood of receiving a passing phantom score by reducing the ambient light and increasing the view box luminance in the location where the images are evaluated and the phantom is scored routinely. Radiologists should also consider increasing phantom and clinical image optical density to allow for improved phantom testing outcomes.

Perspective on digital mammography

Digital mammography, particularly through its advanced applications, holds great promise for improved diagnostic accuracy, but the display of the images is not ideal at present. Clinical softcopy workstations are somewhat unwieldy to use, and image processing has not yet been optimized for each machine or for each clinical task. In addition, the cost-effectiveness and accuracy of the technology warrant careful study before digital mammography becomes widely disseminated and potentially replaces screen-film mammography, a technology that has been well documented to reduce breast cancer mortality.

Fine-Needle Aspiration Biopsy of Nonpalpable Breast Lesions in a Multicenter Clinical Trial: Results from the Radiologic Diagnostic Oncology Group V

PURPOSE

To determine the diagnostic accuracy of ultrasonographically (US) and stereotactically guided fine-needle aspiration biopsy (FNAB) in the diagnosis of nonpalpable breast lesions.

MATERIALS AND METHODS

At 18 institutions, 442 women who underwent 22-25-gauge imaging-guided FNAB were enrolled. Definitive surgical, core-needle biopsy, and/or follow-up information was available for 423 (95.7%) of these women. The reference standard was established from additional clinical and imaging information for an additional six (1.4%) women who did not undergo further histopathologic evaluation. The FNAB protocol was standardized at all institutions, and all specimens were reread by one of two expert cytopathologists.

RESULTS

When insufficient samples were included in the analysis and classified as positive, the sensitivity and specificity of FNAB were 85%-88% and 55.6%-90.5%, respectively; accuracy ranged from 62.2% to 89.2%. The diagnostic accuracy of FNAB was significantly better for detection of masses than for detection of calcifications (67.3% vs. 53.8%, P =.006) and with US guidance than with stereotactic guidance (77.2% vs. 58.9%; P =.002).

CONCLUSION

FNAB of nonpalpable breast lesions has limited value given the high insufficient sample rate and greater diagnostic accuracy of other interventions, including core-needle biopsy and needle-localized open surgical biopsy.

What every surgical oncologist should know about digital mammography

This article reviews the available information on digital mammography for surgeons who care for patients with breast cancer. The limitations of the current film-based technology and why digital mammography promises to improve breast cancer detection and breast lesion diagnosis are described. The basics of digital imaging technology are reviewed, including a description of image contrast and spatial resolution and its variance from currently available clinical digital mammography systems. The results of clinical trials completed to date are reported. An upcoming large screening trial for digital mammography, sponsored by the National Cancer Institute, is described. Future technological developments, including improvements in softcopy display, image processing, computer-aided detection and diagnosis (CADD), tomosynthesis, and digital subtraction mammography (DSM), are briefly discussed.

The American College of Radiology Imaging Network (ACRIN) and its clinical trials in breast imaging

This paper describes the American College of Radiology Imaging Network (ACRIN), a new National Cancer Institute cooperative group, formed to perform multicenter clinical trials in diagnostic imaging and imaging-guided therapeutic technologies. The administrative structure of the organization and the mechanism by which trials are considered and approved for support are detailed. The advantages of this funding mechanism over previous NCI efforts are discussed. Detailed descriptions of the breast imaging protocols that ACRIN will open in the near future are provided. The quality of radiology as an academic discipline is likely to improve due to the infrastructure and training provided by this new organization.

Communicating results of diagnostic mammography: what do patients think?

RATIONALE AND OBJECTIVES

The purpose of this study was to investigate women's preferences for who (radiologist or referring physician) should communicate the results of diagnostic mammography.

MATERIALS AND METHODS

Data from 153 women presenting to two sites for diagnostic mammography between February and June 1995 were collected with a 24-item, self-administered, closed-ended survey. For both normal and abnormal hypothetical results, contingency tables with chi2 tests and multiple logistic regression were used to determine the association, if any, between women's characteristics and their preferences.

RESULTS

Women undergoing diagnostic mammography preferred that their radiologists disclose their normal (90%) and abnormal (88%) mammogram results to them immediately after their examination, rather than have their referring physicians disclose results at a later time. In the case of normal findings, women whose regular physicians were specialists were less likely to want to hear first from their radiologists (odds ratio [OR] = 0.06; 95% confidence interval [CI] = 0.01, 0.77; P = .03), but women who were nervous about learning their results were more likely to want to hear first from their radiologists (OR = 4.5; 95% CI = 1.2, 17.3; P = .03).

CONCLUSION

Radiologists may want to consider assessing women's preferences for who communicates their mammogram results, as most women in this study preferred to hear these results from their radiologists rather than waiting to hear from their referring physicians.

Radiologists' preferences for digital mammographic display. The International Digital Mammography Development Group

PURPOSE

To determine the preferences of radiologists among eight different image processing algorithms applied to digital mammograms obtained for screening and diagnostic imaging tasks.

MATERIALS AND METHODS

Twenty-eight images representing histologically proved masses or calcifications were obtained by using three clinically available digital mammographic units. Images were processed and printed on film by using manual intensity windowing, histogram-based intensity windowing, mixture model intensity windowing, peripheral equalization, multiscale image contrast amplification (MUSICA), contrast-limited adaptive histogram equalization, Trex processing, and unsharp masking. Twelve radiologists compared the processed digital images with screen-film mammograms obtained in the same patient for breast cancer screening and breast lesion diagnosis.

RESULTS

For the screening task, screen-film mammograms were preferred to all digital presentations, but the acceptability of images processed with Trex and MUSICA algorithms were not significantly different. All printed digital images were preferred to screen-film radiographs in the diagnosis of masses; mammograms processed with unsharp masking were significantly preferred. For the diagnosis of calcifications, no processed digital mammogram was preferred to screen-film mammograms.

CONCLUSION

When digital mammograms were preferred to screen-film mammograms, radiologists selected different digital processing algorithms for each of three mammographic reading tasks and for different lesion types. Soft-copy display will eventually allow radiologists to select among these options more easily.

Image processing algorithms for digital mammography: a pictorial essay

Digital mammography systems allow manipulation of fine differences in image contrast by means of image processing algorithms. Different display algorithms have advantages and disadvantages for the specific tasks required in breast imaging-diagnosis and screening. Manual intensity windowing can produce digital mammograms very similar to standard screen-film mammograms but is limited by its operator dependence. Histogram-based intensity windowing improves the conspicuity of the lesion edge, but there is loss of detail outside the dense parts of the image. Mixture-model intensity windowing enhances the visibility of lesion borders against the fatty background, but the mixed parenchymal densities abutting the lesion may be lost. Contrast-limited adaptive histogram equalization can also provide subtle edge information but might degrade performance in the screening setting by enhancing the visibility of nuisance information. Unsharp masking enhances the sharpness of the borders of mass lesions, but this algorithm may make even an indistinct mass appear more circumscribed. Peripheral equalization displays lesion details well and preserves the peripheral information in the surrounding breast, but there may be flattening of image contrast in the nonperipheral portions of the image. Trex processing allows visualization of both lesion detail and breast edge information but reduces image contrast.

Digital mammography, sestamibi breast scintigraphy, and positron emission tomography breast imaging

Digital mammography allows for the separate optimization of image acquisition and display. Through this technology, and the application of image processing and computer aided diagnosis, breast cancer detection and breast lesion diagnosis might be improved. Besides the obvious data storage, retrieval, and transmission advantages that digital mammography will allow, additional advances such as tomosynthesis, dual energy mammography and digital subtraction mammography are in development. The possible future utility of Sestamibi breast scintigraphy and breast imaging with positron emission tomography is also discussed.

Informing patients of diagnostic mammography results: mammographer's opinions

PURPOSE

The authors' purpose was to determine mammographers' practices and attitudes regarding disclosing results of diagnostic mammograms to patients.

MATERIALS AND METHODS

In 1995, the authors mailed a questionnaire to 500 members of the Society of Breast Imaging; 399 (80%) responded to the survey.

RESULTS

Three-quarters of respondents stated that mammographers should disclose results to their patients, and approximately half were already doing so (52% for normal results, 51% for abnormal results). A sizable minority (25%) said that not telling patients was the best practice and identified several barriers to direct disclosure, including lack of time. Although bivariate analysis showed direct disclosure to be more common among female mammographers, the sex difference did not persist in multivariate analysis. In both bivariate and multivariate analyses, reading more than 100 mammograms per week and having a radiology practice in a university or academic setting were each strongly associated with direct disclosure.

CONCLUSION

Implementation of the Mammography Quality Standards Reauthorization Act of 1998 may not require a major change in mammographers' current practice. It remains critical to establish systems that help radiologists disclose results and communicate with referring physicians efficiently and effectively.

Has the mammography quality standards act affected the mammography quality in North Carolina?

OBJECTIVE

The United States Food and Drug Administration implemented federal regulations governing mammography under the Mammography Quality Standards Act (MQSA) of 1992. During 1995, its first year in implementation, we examined the impact of the MQSA on the quality of mammography in North Carolina.

MATERIALS AND METHODS

All mammography facilities were inspected during 1993-1994, and again in 1995. Both inspections evaluated mean glandular radiation dose, phantom image evaluation, darkroom fog, and developer temperature. Two mammography health specialists employed by the North Carolina Division of Radiation Protection performed all inspections and collected and codified data.

RESULTS

The percentage of facilities that met quality standards increased from the first inspection to the second inspection. Phantom scores passing rate was 31.6% versus 78.2%; darkroom fog passing rate was 74.3% versus 88.5%; and temperature difference passing rate was 62.4% versus 86.9%.

CONCLUSION

In 1995, the first year that the MQSA was in effect, there was a significant improvement in the quality of mammography in North Carolina. This improvement probably resulted from facilities' compliance with federal regulations.

Human breast cancer specimens: diffraction-enhanced imaging with histologic correlation--improved conspicuity of lesion detail compared with digital radiography

Seven breast cancer specimens were examined with diffraction-enhanced imaging at 18 keV with a silicon crystal with use of the silicon 333 reflection in Bragg mode. Images were compared with digital radiographs of the specimen, and regions of increased detail were identified. Six of the seven cases (86%) showed enhanced visibility of surface spiculation that correlated with histopathologic information, including extension of tumor into surrounding tissue.

Effect of display luminance on the feature detection rates of masses in mammograms

Our purpose in this study was to determine the importance of the luminance range of the display system for the detection of simulated masses in mammograms. Simulated masses were embedded in selected portions (512 x 512 pixels) of mammograms digitized at 50 micro pixels, 12 bits deep. The masses were embedded in one of four quadrants in the image. An observer experiment was conducted in which the observer's task was to determine in which quadrant the mass is located. The key variables involved in each trial included the position of the mass, the contrast level of the mass, and the luminance of the display. The contrast of the mass with respect to the background was fixed to one of four selected contrast levels. The digital images were printed to film, and displayed on a mammography lightbox. The display luminance was controlled by placing neutral density films between the laser printed films of mammographic backgrounds and the lightbox. The resulting maximum luminances examined in this study ranged from 34 cd/m2 to 2056 cd/m2. Twenty observers viewed 80 different images (20 observations at each of 4 different mass contrast levels) under each of the 5 luminance conditions for a total of 800 independent observations per observer. An analysis of variance yielded no statistically significant correlation between the luminance range of the display and the feature detection rate of the simulated masses in mammograms. However, the performance of the lower luminance display systems (less than 300 cd/m2), may be reduced due to the high levels of ambient light found in many reading environments.

Effects of processing conditions on mammographic image quality

RATIONALE AND OBJECTIVES

Any given mammographic film will exhibit changes in sensitometric response and image resolution as processing variables are altered. Developer type, immersion time, and temperature have been shown to affect the contrast of the mammographic image and thus lesion visibility. The authors evaluated the effect of altering processing variables, including film type, developer type, and immersion time, on the visibility of masses, fibrils, and speaks in a standard mammographic phantom.

MATERIALS AND METHODS

Images of a phantom obtained with two screen types (Kodak Min-R and Fuji) and five film types (Kodak Min-R M, Min-R E, Min-R H; Fuji UM-MA HC, and DuPont Microvision-C) were processed with five different developer chemicals (Autex SE, DuPont HSD, Kodak RP, Picker 3-7-90, and White Mountain) at four different immersion times (24, 30, 36, and 46 seconds). Processor chemical activity was monitored with sensitometric strips, and developer temperatures were continuously measured. The film images were reviewed by two board-certified radiologists and two physicists with expertise in mammography quality control and were scored based on the visibility of calcifications, masses, and fibrils.

RESULTS

Although the differences in the absolute scores were not large, the Kodak Min-R M and Fuji films exhibited the highest scores, and images developed in White Mountain and Autex chemicals exhibited the highest scores.

CONCLUSION

For any film, several processing chemicals may be used to produce images of similar quality. Extended processing may no longer be necessary.

Contrast limited adaptive histogram equalization image processing to improve the detection of simulated spiculations in dense mammograms

The purpose of this project was to determine whether Contrast Limited Adaptive Histogram Equalization (CLAHE) improves detection of simulated spiculations in dense mammograms. Lines simulating the appearance of spiculations, a common marker of malignancy when visualized with masses, were embedded in dense mammograms digitized at 50 micron pixels, 12 bits deep. Film images with no CLAHE applied were compared to film images with nine different combinations of clip levels and region sizes applied. A simulated spiculation was embedded in a background of dense breast tissue, with the orientation of the spiculation varied. The key variables involved in each trial included the orientation of the spiculation, contrast level of the spiculation and the CLAHE settings applied to the image. Combining the 10 CLAHE conditions, 4 contrast levels and 4 orientations gave 160 combinations. The trials were constructed by pairing 160 combinations of key variables with 40 backgrounds. Twenty student observers were asked to detect the orientation of the spiculation in the image. There was a statistically significant improvement in detection performance for spiculations with CLAHE over unenhanced images when the region size was set at 32 with a clip level of 2, and when the region size was set at 32 with a clip level of 4. The selected CLAHE settings should be tested in the clinic with digital mammograms to determine whether detection of spiculations associated with masses detected at mammography can be improved.

Paget disease of the breast: a pictorial essay

Paget disease of the breast accounts for approximately 2%-3% of breast cancers. It is characterized by infiltration of the nipple epidermis by adenocarcinoma cells, which cause an eczematous eruption on the nipple and areola. The clinical features are highly suggestive of the disease; awareness of these on the part of the clinician should lead to more prompt diagnosis and earlier initiation of appropriate treatment. Mammograms, although not always positive, should be obtained in all cases suggestive of Paget disease to search for the underlying tumor and direct further treatment. Findings that may be seen at mammography include skin thickening, nipple retraction, subareolar or more diffuse malignant microcalcifications, and a discrete mass or masses. However, a negative mammogram should not alter the course of treatment. Conversely, identification of subareolar mammographic findings should alert the clinician to search for physical signs in the nipple and areolar region suggestive of Paget disease.

Educational outreach to mammography facility staff to assist with compliance with the Mammography Quality Standards Act in rural North Carolina

RATIONALE AND OBJECTIVES

The purpose of this project was to develop and evaluate an educational program targeted at mammography facilities in rural areas of North Carolina that were having difficulty complying with the 1992 Mammography Quality Standards Act (MQSA).

MATERIALS AND METHODS

Fourteen facilities deemed at risk for closure under MQSA were identified by state inspection personnel. Problems at the facilities were evaluated by a radiologist, a physicist-educator, and a radiation physicist through a written survey, review of phantom and clinical images, and a site visit. Individual advice and instruction were provided on-site by the physicist-educator, with written materials provided in follow-up. A repeat site visit was made 4-6 months after the initial visit.

RESULTS

Of 51 problems identified at the 12 institutions that completed the program, 35 (69%) were corrected. All facilities that had failing phantom scores at the inspection prior to the intervention had passing scores at the inspection after the intervention. There was a statistically significant increase in the sum of the phantom scores for the facilities offered this intervention compared with those not offered it (P = .03).

CONCLUSION

This educational program improved mammography quality at participating facilities.

Screening behavior of women after a false-positive mammogram

PURPOSE

To determine the effect of a false-positive mammogram that leads to open surgical biopsy on subsequent screening mammography behavior in women.

MATERIALS AND METHODS

This study was performed with a retrospective cohort design, and data were collected by means of telephone interview. All participants were women aged at least 50 years, with no history of breast cancer. Study patients (n = 43) were women who had an abnormal mammogram followed within 6 months by benign excisional breast biopsy. Control subjects (n = 136) were randomly selected: They included women with a normal mammogram who had not undergone biopsy, as well as women with an abnormal mammogram and the recommendation to undergo 6-month follow-up mammography.

RESULTS

Two differences between the study and control groups were statistically significant. Study patients were more likely than control patients to believe they had increased susceptibility to breast cancer (P = .039). Study patients were also more likely than control subjects to intend to undergo screening mammography annually in the future (P = .036).

CONCLUSION

A false-positive mammogram that leads to open surgical biopsy does not inhibit most women from undergoing subsequent screening mammography. In fact, such an experience may increase their intentions to undergo regular screening.

Screening mammography behavior after a false positive mammogram

This pilot study describes women's interpretations of the experience of a false positive mammogram followed by a negative biopsy and the impact of this experience on subsequent participation in screening mammography. A 25-min, open-ended telephone interview was administered in 1992 to 30 women over age 39 who had negative biopsies in 1987 preceded by abnormal mammograms. Almost twice as many women reported getting regular mammograms after the biopsy (60%) as did before 1987 (33%). Most received their next mammogram after the biopsy within the recommended interval (73%), and those getting regular mammograms prior to the biopsy experience were more likely than those who did not have a prior habit of undergoing mammography to continue to get them afterwards. These preliminary findings suggest that a negative breast biopsy after a positive mammogram does not reduce a patient's likelihood of undergoing screening in the future. In fact, it may serve as an impetus for increased compliance with screening recommendations.

Rate of insufficient samples for fine-needle aspiration for nonpalpable breast lesions in a multicenter clinical trial: The Radiologic Diagnostic Oncology Group 5 Study. The RDOG5 investigators

BACKGROUND

Radiologic Diagnostic Oncology Group 5 is a multicenter clinical trial designed to evaluate fine-needle aspiration (FNA) of nonpalpable breast lesions performed by multiple operators using the same protocol.

METHODS

Four hundred and nineteen women with mammographically detected nonpalpable breast lesions were enrolled on the trial at 18 institutions. Group A institutions randomized women to stereotactically guided FNA (SFNA) followed by stereotactically guided core needle biopsy (SCNB), or SCNB only. Group B institutions randomized women to SFNA and SCNB, SCNB, or ultrasonographically guided FNA followed by ultrasonographically guided core needle biopsy (USCNB), or USCNB only. A total of 377 women were eligible for analysis.

RESULTS

FNA yielded 128 insufficient samples for the 377 patients (33.95%; 95% confidence interval, 29.2-38.7%). The rate of insufficient samples varied by type of lesion with calcified lesions associated with a significantly higher rate of insufficient sampling than masses (P < 0.001). The radiologist's level of suspicion of the lesion was not a statistically significant predictor of insufficient samples for mass lesions, but was a predictor for calcified lesions. For the 336 lesions for which histologic information was available, insufficient samples occurred in significantly more benign than malignant lesions.

CONCLUSIONS

The high rate of insufficient samples for FNA of nonpalpable breast lesions in this multicenter trial makes its use impractical in this setting. Because of this factor, the study was terminated early.

Future directions in imaging of breast diseases

In the near future, investigation and refinement of emerging anatomic and functional breast imaging techniques will enable clinical trials that will evaluate their utility and potential for improving the survival and quality of life for patients with breast cancer. In the longer term, strategic research collaborations among investigators in the fields of functional imaging, molecular biology, and pathology are needed to merge existing science and advance the development of biomarker and genetic techniques focused on detecting and characterizing disease at the cellular and molecular levels. This research could create clinical tools for (a) detecting breast cancer earlier, (b) more accurately quantifying the extent of disease, (c) noninvasively evaluating lymph node involvement, (d) identifying micrometastases and residual microscopic disease, and (e) enhancing therapy by means of imaging-guided biomarker or tumor-specific delivery of pharmacologic, chemosensitizing, or radiosensitizing agents to tumors.

The effect of intensity windowing on the detection of simulated masses embedded in dense portions of digitized mammograms in a laboratory setting

The purpose of this study was to determine whether intensity windowing (IW) improves detection of simulated masses in dense mammograms. Simulated masses were embedded in dense mammograms digitized at 50 microns/pixel, 12 bits deep. Images were printed with no windowing applied and with nine window width and level combinations applied. A simulated mass was embedded in a realistic background of dense breast tissue, with the position of the mass (against the background) varied. The key variables involved in each trial included the position of the mass, the contrast levels and the IW setting applied to the image. Combining the 10 image processing conditions, 4 contrast levels, and 4 quadrant positions gave 160 combinations. The trials were constructed by pairing 160 combinations of key variables with 160 backgrounds. The entire experiment consisted of 800 trials. Twenty observers were asked to detect the quadrant of the image into which the mass was located. There was a statistically significant improvement in detection performance for masses when the window width was set at 1024 with a level of 3328. IW should be tested in the clinic to determine whether mass detection performance in real mammograms is improved.

Does intensity windowing improve the detection of simulated calcifications in dense mammograms?

This study attempts to determine whether intensity windowing (IW) improves detection of simulated calcifications in dense mammograms. Clusters of five simulated calcifications were embedded in dense mammograms digitized at 50-microns pixels, 12 bits deep. Film images with no windowing applied were compared with film images with nine different window widths and levels applied. A simulated cluster was embedded in a realistic background of dense breast tissue, with the position of the cluster varied. The key variables involved in each trial included the position of the cluster, contrast level of the cluster, and the IW settings applied to the image. Combining the ten IW conditions, four contrast levels and four quadrant positions gave 160 combinations. The trials were constructed by pairing 160 combinations of key variables with 160 backgrounds. The entire experiment consisted of 800 trials. Twenty student observers were asked to detect the quadrant of the image in which the mass was located. There was a statistically significant improvement in detection performance for clusters of calcifications when the window width was set at 1024 with a level of 3328, and when the window width was set at 1024 with a level of 3456. The selected IW settings should be tested in the clinic with digital mammograms to determine whether calcification detection performance can be improved.

A pilot study of eye movement during mammography interpretation: eyetracker results and workstation design implications

Digital mammography can potentially improve mammography image and interpretation quality. On-line interpretation from a workstation may improve interpretation logistics and increase availability of comparison images. Interpretation of eight 4k- x 5k-pixel mammograms on two to four 2k- x 2.5k-pixel monitors is problematic because of the time spent in choosing which images display on which monitors, and zooming and roaming on individual images that are too large to display completely at full resolution. The authors used an eyetracker to measure radiologists viewing behavior during mammography interpretation with film on a viewbox. It was observed that a significant portion of the mammographers' time is spent viewing "comparison pairs" (typically two or more comparisons per case), such as the left mediolateral and craniocaudal images or old and new images. From the eyetracker measurements, we estimated that the number of image display, roam, and zoom operations decreases from an average of 64 for one monitor to 31 for four monitors, with the largest change going from one to two monitors. We also show that fewer monitors with a faster response time is superior to more monitors with a slower response time. Finally, the authors demonstrate the applicability of time-motion analysis to mammographic workstation design.

Ultrasound and MR findings in acute Budd-Chiari syndrome with histopathologic correlation

This report describes the sonographic and MR appearances of acute Budd-Chiari syndrome (BCS) in a 30-year-old woman. Current imaging techniques including duplex Doppler sonography and dynamic gadolinium-enhanced MRI were employed, and direct histopathologic correlation was made. Duplex Doppler sonography revealed a heterogeneous enlarged liver, no flow in the left and middle hepatic veins, and only trace abnormal flow in the distal-most right hepatic vein. Dynamic serial gadolinium-enhanced, spoiled gradient echo imaging demonstrated early homogeneous enhancement of an enlarged caudate lobe, as well as heterogeneously decreased enhancement of the remainder of the hepatic parenchyma. This differential enhancement pattern persisted on delayed imaging. Patent hepatic veins were not demonstrated on any sequence. Associated findings included hepatomegaly, ascites, and patent portal vasculature. These imaging findings were interpreted as consistent with acute BCS. Within 10 days, the patient underwent orthotopic liver transplantation. Histopathology demonstrated hepatic necrosis and hepatic venous thrombosis consistent with acute BCS.

Patient compliance in mobile screening mammography

RATIONALE AND OBJECTIVES

We assessed the follow-up behavior of women who had abnormal results of screening mammograms taken on a mobile van.

METHODS

A retrospective cohort study was conducted between 1988 and 1991 of all women served by a mobile mammography van in rural North Carolina. Compliance with radiologist recommendations for follow-up was assessed through review of patient records and mail surveys of patients with incomplete records.

RESULTS

Compliance was 44% for negative or benign mammograms, 57% for indeterminate mammograms, and 62% for probably malignant or malignant mammograms. Women who had a previous mammogram or had a malignant finding were more likely to comply with follow-up recommendations (p < .0001) than women with normal or benign results and no history of mammography. Compliers and noncompliers did not differ with respect to family history of breast cancer or personal history of breast discomfort.

CONCLUSION

Compliance with recommendations in this setting was lower than expected. This may be because rural women using mobile van mammography have limited access to the resources needed for appropriate follow-up. Further research is needed to examine explanations for poor compliance in this setting.

New modalities in breast imaging: digital mammography and magnetic resonance imaging

Mammography is currently the only screening method available with proven capability to diagnose nonpalpable breast cancer. However, mammography does not detect all cancers. Cancers are more difficult to detect in radiographically dense breasts because lesions are obscured by breast tissue. Digital mammography and magnetic resonance imaging of the breast may minimize the problems associated with screening dense breasts. If these methods prove to be useful, more cancers could be detected at an earlier stage.

Eye movement during computed tomography interpretation: eyetracker results and image display-time implications

Stacked displays hold the potential for accurate interpretation of multiple computed tomography (CT) studies on a low-cost workstation. But can such a display scroll as quickly as radiologists can move their eyes to the next image on a film? To address this question, eye-movement duration during CT chest interpretation was recorded using an electronic eye tracker. Adjacent eye movements (+/- 1 image in sequence) averaged 0.54 seconds. Time motion analysis indicates that a CT workstation using a stacked approach with a 0.2-second image display time and a simple interaction can display the next image in less than 0.4 seconds, so a stacked approach should allow a low-cost workstation to facilitate acceptable interpretation of multiple CT or magnetic resonance studies. However, nonadjacent eye movements is likely to take longer and radiologist behavior may be effected.

A method for determination of optimal image enhancement for the detection of mammographic abnormalities

We present a paradigm for empirical evaluation of digital image enhancement algorithms for mammography that uses psychophysical methods for implementation and analysis of a clinically relevant detection task. In the experiment, the observer is asked to detect and assign to a quadrant, or indicate the absence of, a simulated mammographic structure characteristic of cancer embedded in a background image of normal breast tissue. Responses are indicated interactively on a computer workstation. The parameter values for the enhancement applied to the composite image may be varied on each trial, and structure detection performance is estimated for each enhancement condition. Preliminary investigations have provided insight into an appropriate viewing duration, and furthermore, suggest that nonradiologists may be used under this methodology for the tasks investigated thus far, for predicting parameter values for clinical investigation. We are presently using this method in evaluating several contrast enhancement algorithms of possible benefit in mammography. These methods enable an objective, clinically relevant evaluation, for the purpose of optimal parameter determination or performance assessment, of digital image-processing methods potentially used in mammography.

Computed tomography interpretations with a low-cost workstation: a timing study

An ergonomically simple prototype workstation with two 900 x 1,100-pixel monitors capable of displaying eight full-resolution computed tomography (CT) images in 0.2 seconds, was compared with film for interpretation of computed tomographic images of the chest and abdomen. The hardware platform for this workstation cost less than $11,500 in 1993. A repeated-measures experiment was used to generate average interpretation times of 6.17 minutes for the workstation and 6.03 minutes for the film, including loading and unloading films, with three of the four subjects averaging about a minute longer for each workstation interpretation. All dictated reports were of clinically acceptable accuracy. All radiologists stated that workstations based on this design would be an acceptable clinical tool. However, observation suggested human working-memory strain among infrequent CT readers that could indicate the need for additional training. These data suggest that low-cost workstations can have practical application in interpretation of digital medical images such as CT, with the possibility of small increases in interpretation time.

Breast imaging fellowship programs. A survey of the fellows of the Society of Breast Imaging

RATIONALE AND OBJECTIVES

Breast imaging, a subspecialty of diagnostic radiology, is becoming more important with the increased performance of screening mammography. Fellowships in breast imaging are being offered at many institutions. Information regarding the contents and structure of such fellowships is important for potential trainees and departments considering offering such programs.

METHODS

All 79 fellows of the Society of Breast Imaging (SBI) were surveyed by mail. Those with breast imaging fellowships were asked questions about their program. All were asked their opinions about the appropriate features of a breast imaging fellowship.

RESULTS

Forty-six (58%) surveys were returned. Nineteen respondents described breast imaging fellowships offered at 18 different institutions.

CONCLUSIONS

This information may be useful as radiologists consider establishing fellowship standards within this subspecialty.

Effects of delayed processing on mammographic phantom object detection

OBJECTIVES

Delayed processing of films is a common occurrence in mobile mammography screening programs. The effects of such delayed processing on radiologists' detection of phantom test objects are investigated.

METHODS

Twelve screen-film combinations were exposed using a phantom and developed after delays of 0, 1, 2, 3, 5, and 7 days. Films were scored by three board-certified radiologists specializing in mammography, based on visibility of calcifications, masses, fibrils, and line pairs.

RESULTS

Variance analyses of mean scores indicate that, across screen-film combinations, there are no statistically significant decreases in object detection associated with delayed processing. The analyses do indicate, however, a statistically significant difference in scores unrelated to delay, attributable to the screen-film combination used.

CONCLUSIONS

Delayed processing of mammography film does not lead to a decrease in the visibility of phantom test objects, despite large decreases in overall image optical density.

An update on mammography

For at least 7°% of breast cancers there are no known causal factors other than gender and aging. Other possible risk factors include hormonal, genetic, nutritional, morphologic, environmental (chemical, pesticides, food additives), irradiation, and viruses. Japanese women have much less breast cancer than women in the U.S.A., and after age 45, their incidence levels off or falls, whereas ours continues to rise. Furthermore, within a generation or two of moving to the U.S.A., Japanese women have a similar incidence to ours! What are we doing that increases our risk for this disease? It would certainly suggest that the other risk factors are involved and much research continues to explore this. Screening with mammography and breast physical examination is the cornerstone of earlier detection, improved survival and reduced mortality from breast cancer. A variety of studies and improvement in stage trends support this. Despite this, overall mortality from breast cancer remains unchanged. However, increasing incidence with stable mortality would suggest there is some reduction in overall mortality. Some other reasons for no reduction in overall mortality include: I. The variable biological forms and natural history of the disease. Assuming an average 100 days doubling time, cancer has been present in a woman's breast if not elsewhere for 6-7 years or longer before it is potentially detectable by mammography or breast physical examination. The extent of disease, cell type and grade, and host resistance are all important survival factors. Not enough breast cancers are at an early stage when diagnosed and treated. Not enough eligible women are being routinely screened with optimum mammography and breast physical examination. There is too much reliance on breast self-examination and breast physical examination alone for detection.

Real-time radiologist review of remote ultrasound using low-cost video and voice

RATIONALE AND OBJECTIVES

A radiologist practicing remote ultrasound occasionally needs to review a case in real time before releasing the patient. The authors conducted a pilot study to evaluate one solution in which the radiologist views real-time images on a video monitor while conversing with the technologist via a headset telephone.

METHODS

Two experienced ultrasonographers and five technologies participated in a 5-week pilot study in adjacent rooms.

RESULTS

Subjective assessment indicated that the system could function well enough for use at a remote site.

CONCLUSIONS

Although this technology appears effective, an ongoing training environment is recommended.

A formal curriculum in breast imaging for radiology residents

RATIONAL AND OBJECTIVES

Training in breast imaging is highly variable among radiology programs. The authors have developed a standardized breast imaging curriculum for radiology residents.

METHODS

This curriculum has been implemented within the residency program at the University of North Carolina at Chapel Hill. It includes nine standardized components: 1) the clinical activities of the service; 2) the study of breast imaging teaching file films and contribution of new cases; 3) selected readings; 4) formal discussion with faculty on the readings; 5) review of this material using an interactive computer program; 6) formal conferences; 7) technical and quality control activities; 8) research activities; and 9) an evaluation. The participating residents have been surveyed regarding their opinions of their educational experience.

RESULTS AND CONCLUSION

The standardized curriculum has been well received by the participating residents. Conclusions about the educational efficacy of such a curriculum cannot be made until more residents have used it.