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.

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.

Challenges in mammography: part 1, artifacts in digital mammography.

OBJECTIVE: Early detection of breast cancer is directly related to the radiologist's ability to detect abnormalities visible only on mammograms. Artifacts on mammograms reduce image quality and may present clinical and technical difficulties for the radiologist, mammography technologist, medical physicist, and equipment service personnel. CONCLUSION: In this article, we will illustrate the appearance of artifacts in full field digital mammography, review the causes of these artifacts, and discuss methods to eliminate artifacts in digital mammography.

Detection of microcalcifications on digital screening mammograms using varying degrees of monitor zooming.

OBJECTIVE: The American College of Radiology recommends that mammogram images be viewed at 100% resolution (also called one-to-one or full resolution). We tested the effect of this and three other levels of zooming on the ability of radiologists to identify malignant calcifications on screening mammographic views. MATERIALS AND METHODS: Seven breast imagers viewed 77 mammographic images, 32 with and 45 without malignant microcalcifications, using four different degrees of monitor zooming. The readers indicated whether they thought a cluster of potentially malignant calcifications was present and where the cluster was located. Tested degrees of zooming included fit screen, a size midway between fit screen and 100%, 100%, and a size slightly larger than 100%. RESULTS: Readers failed to detect 17 clusters of malignant calcifications with fit-screen images, 12 clusters with midway images, 13 clusters with 100% images, and 11 clusters with slightly larger images. When viewing images without malignant microcalcifications, the readers marked false-positive areas on 25 images using fit-screen images, 43 of the midway images, 40 of the 100% images, and 29 of the slightly larger images. CONCLUSION: All four tested levels of zooming functioned well. There was a trend for the fit-screen images to function slightly less well than the others with regard to sensitivity, so it may not be prudent to rely on those images without other levels of zooming. The 100% resolution images did not function noticeably better than the others.

Interpretation time of computer-aided detection at screening mammography.

PURPOSE: To prospectively determine the interpretation time associated with computer-aided detection (CAD) and to analyze how CAD affected radiologists' decisions and their level of confidence in their interpretations of digital screening mammograms. MATERIALS AND METHODS: An Institutional Review Board exemption was obtained, and patient consent was waived in this HIPAA compliant study. The participating radiologists gave informed consent. Five radiologists were prospectively studied as they interpreted 267 clinical digital screening mammograms. Interpretation times, recall decisions, and confidence levels were recorded without CAD and then with CAD. Software was used for linear regression fitting of interpretation times. P values less than .05 were considered to indicate statistically significant differences. RESULTS: Mean interpretation time without CAD was 118 seconds ± 4.2 (standard error of the mean). Mean time for reviewing CAD images was 23 seconds ± 1.5. CAD identified additional findings in five cases, increased confidence in 38 cases, and decreased confidence in 21 cases. Interpretation time without CAD increased with the number of mammographic views (P < .0001). Mean times for interpretation without CAD and review of the CAD images both increased with the number of CAD marks (P < .0001). The interpreting radiologist was a significant variable for all interpretation times (P < .0001). Interpretation time with CAD increased by 3.2 seconds (95% confidence interval: 1.8, 4.6) for each calcification cluster marked and by 7.3 seconds (95% confidence interval: 4.7, 9.9) for each mass marked. CONCLUSION: The additional time required to review CAD images represented a 19% increase in the mean interpretation time without CAD. CAD requires a considerable time investment for digital screening mammography but may provide less measureable benefits in terms of confidence of the radiologists.

Evaluation of stylus for radiographic image annotation.

We evaluated the use of a stylus as a computer interface for radiographic image annotation. Our case study concerned the annotation of spiculated lesions on mammograms. Three experienced radiologists annotated 20 mammograms depicting spiculated lesions. We evaluated the interobserver agreement in annotations marked with a stylus versus those marked with a mouse using the intraclass correlation coefficient. Better agreement in annotating spicule width was observed with the stylus, suggesting that it is easier to accurately annotate subtle regions on an image using a stylus.

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.

The many faces of fat necrosis in the breast.

OBJECTIVE: This article describes the manifestations of fat necrosis on mammography, sonography, and MRI and correlates the imaging findings with the pathologic findings. CONCLUSION: On imaging studies, the appearance of fat necrosis ranges from typically benign to worrisome for malignancy. Mammography is more specific than sonography, and emphasis should be placed on mammography in making the diagnosis of fat necrosis. In selected cases, MRI may be helpful in showing findings consistent with fat necrosis.

Timed efficiency of interpretation of digital and film-screen screening mammograms.

OBJECTIVE: Our objective was to compare interpretation speeds for digital and film-screen screening mammograms to test whether other variables might affect interpretation times and thus contribute to the apparent difference in interpretation speed between digital mammograms and film-screen mammograms, and to test whether the use of digital rather than film comparison studies might result in significant time savings. MATERIALS AND METHODS: Four readers were timed in the course of actual clinical interpretation of digital mammograms and film-screen mammograms. Interpretation times were compared for subgroups of studies based on the interpretation of the study by BI-RADS code, the number of images, the presence or absence of comparison studies and the type of comparison study, and whether the radiologist personally selected and hung additional films; the same comparisons were made among individual readers. RESULTS: For all four readers, mean interpretation times were longer for digital mammograms than for film-screen mammograms, with differences ranging from 76 to 202 seconds. The difference in interpretation speed between digital and film-screen mammograms was independent of other variables. Digital mammogram interpretation times were significantly longer than film-screen mammogram interpretation times regardless of whether the digital mammograms were matched with film or digital comparison studies. CONCLUSION: In screening mammography interpretation, digital mammograms take longer to read than film-screen mammograms, independent of other variables. Exclusive use of digital comparison studies may not cause interpretation times to drop enough to approach the interpretation time required for film-screen mammograms.

The Use of Chemotherapy to Prolong the Life of Dogs Suffering from Cancer: The Ethical Dilemma.

Despite the emergence some years ago of oncology as a veterinary specialty, there has been very little in the way of ethical debate on the use of chemotherapy in dogs. The purpose of this article is to undertake an ethical analysis to critically examine the use of chemotherapy to prolong the life of dogs suffering from cancer. If dogs have no concept of the future and are likely to suffer at least some adverse effects with such treatments, consideration should be given as to whether it is ethical and in the animal's best interests to use chemotherapy. Chemotherapeutic drugs are mutagenic, carcinogenic, teratogenic and may be irritant. Furthermore, chemotherapy may involve multiple trips to the veterinarian, multiple procedures and periods in isolation. Cancer-associated pain has been shown to be under-diagnosed and pet owners overestimate the effects of chemotherapy on treatment survival time. Of additional concern is the public health risks associated with chemotherapeutic drugs. As chemotherapy is not generally considered curative, it is in effect palliative care. However, palliative care may not be in the best interests of a terminally ill animal. As the specialty of veterinary oncology continues to grow and as the use of chemotherapy becomes more commonplace in the treatment of animals with cancer, it is imperative that there is an ongoing ethical debate on the use of chemotherapy in animals.

Comparison of slot scanning digital mammography system with full-field digital mammography system.

The purpose of this study was to evaluate and compare microcalcification detectability of two commercial full-field digital mammography (DM) systems. The first unit was a flat panel based DM system (FFDM) which employed an anti-scatter grid method to reject scatter, and the second unit was a charge-coupled device-based DM system (SSDM) which used scanning slot imaging geometry to reduce scatter radiation. Both systems have comparable scatter-to-primary ratios. In this study, 125-160 and 200-250 microm calcium carbonate grains were used to simulate microcalcifications and imaged by both DM systems. The calcium carbonate grains were overlapped with a 5-cm-thick 50% adipose/50% glandular simulated breast tissue slab and an anthropomorphic breast phantom (RMI 165, Gammex) for imaging at two different mean glandular dose levels: 0.87 and 1.74 mGy. A reading study was conducted with seven board certified mammographers with images displayed on review workstations. A five-point confidence level rating was used to score each detection task. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (A(z)) was used to quantify and compare the performances of these two systems. The results showed that with the simulated breast tissue slab (uniform background), the SSDM system resulted in higher A(z)'s than the FFDM system at both MGD levels with the difference statistically significant at 0.87 mGy only. With the anthropomorphic breast phantom (tissue structure background), the SSDM system performed better than the FFDM system at 0.87 mGy but worse at 1.74 mGy. However, the differences were not found to be statistically significant.

Primary breast cancer in men: clinical, imaging, and pathologic findings in 57 patients.

OBJECTIVE: The purpose of our study was to describe the imaging findings in primary breast cancer in men. MATERIALS AND METHODS: Male patients from a single pathology database with the histologic diagnosis of breast cancer who had undergone preoperative mammography or sonography were included in this study. The mammograms and sonograms were retrospectively reviewed according to the American College of Radiology BI-RADS lexicon. Patients who did not have films available but had imaging reports available for review were also included. Sonograms of the regional nodal basins, including axillary, infraclavicular, internal mammary, and supraclavicular regions, were noted. Histopathology subtype of breast cancer and axillary nodal status were documented. RESULTS: A total of 57 patients with imaging and 187 patients without imaging were included. The median age was 62 years (range, 19-80 years). Forty-nine patients had undergone both mammography and sonography; six, mammography alone; and two, sonography alone. Ninety-five percent (54/57) of patients presented with a palpable mass and 4% (2/57) with nipple inversion. At mammography, 69% (38/55) of cancers showed a mass; 29% (16/55), mass with microcalcifications; and 2% (1/55), microcalcifications. Gynecomastia was noted in 22 (40%) of 55 patients. Mammographic features included an irregular mass with spiculated or indistinct margins. Calcifications were typically pleomorphic and segmental. Sonographic features were typically an irregular mass with microlobulated margins. Axillary nodal involvement was present in 47% of patients. Most cancers were ductal carcinoma, either invasive or in situ. CONCLUSION: Breast cancer in men characteristically presents as an irregular subareolar mass with spiculated or indistinct margins on mammography and can be associated with calcifications and gynecomastia. Sonography has a role in regional staging of lymph nodes.

Primary pulmonary carcinoma in patients with idiopathic pulmonary fibrosis.

OBJECTIVE: To identify distinguishing characteristics between patients with idiopathic pulmonary fibrosis (IPF) and primary lung carcinoma and patients with either IPF or carcinoma alone. PATIENTS AND METHODS: The study group consisted of 24 patients with histologically proven usual interstitial pneumonia and lung carcinoma identified through a search of the Rochester Mayo Clinic database for 1990 to 1998. Medical records, radiographs, and histological slides were reviewed. Several variables including survival were compared in 2 control groups, IPF only and carcinoma only, by using various statistical methods. RESULTS: Our study group included 21 men and 3 women (mean age, 72.3 years). Twenty-two were past or current smokers. Approximately half of the lung carcinomas were incidental findings. Of the 14 patients with preoperative computed tomographic scans, 12 had peripheral tumors situated in areas of fibrosis. Squamous cell carcinoma was the most common histological type, accounting for 16 cases. Almost all patients underwent surgical treatment; nearly 40% developed postoperative complications, and 3 died within 30 days of surgery. The ratio of men to women in patients with IPF and carcinoma was 7:1 compared with 1:1 in patients with IPF only (P=.003). Patients with IPF and carcinoma were also older, with a mean age of 72.3 years compared with 64.4 years (P=.001), and were more often smokers (P=.002). Carcinomas involved the lower lobes in 42% of patients with IPF and carcinoma compared with 29% of patients with carcinoma only (P=.004) and were mainly composed of squamous cell carcinoma (P=.004). Mean survival in patients with IPF and lung carcinoma was 2.3 years after the diagnosis of IPF and 1.6 years after that of carcinoma. This finding did not differ significantly from survival of patients with either IPF or carcinoma alone. However, statistical power was limited. CONCLUSION: Carcinoma in patients with IPF arises in older male smokers and usually presents as peripheral squamous cell carcinoma. The prognosis is poor.

Surgical decision making and factors determining a diagnosis of breast carcinoma in women presenting with nipple discharge.

BACKGROUND: There is no consensus about the use of the various diagnostic tests and surgical procedures available to confirm or rule out breast cancer in patients presenting with nipple discharge. This study was designed to identify patient and nipple-discharge characteristics associated with the diagnosis of breast cancer and to determine the utility of mammography, sonography, ductography, and cytology in surgical decision making in patients presenting with pathologic nipple discharge. STUDY DESIGN: We reviewed the medical records of all patients who presented with nipple discharge at our institution between August 1993 and September 2000. Patient and nipple-discharge characteristics and findings on imaging studies and cytologic examination were analyzed. RESULTS: A total of 146 patients presented at our institution with nipple discharge during the study period. Of these, 52 had clinically benign discharge and were managed without surgical intervention; 94 patients had pathologic discharge and underwent a biopsy procedure for histologic diagnosis, treatment, or both. Logistic regression analysis identified mammographic (relative risk [RR] = 10.47, 95% confidence interval [CI] 2.36 to 46.39, p = 0.0002) and sonographic (RR = 5.54, 95% CI 1.27 to 25.40, p = 0.028) abnormalities as independent factors associated with a malignant diagnosis. Nineteen cancers, 62 papillomas, and 13 other benign lesions were identified among the patients with pathologic discharge. In 3 patients with cancer (15.8%) and 30 patients with a papilloma (48.4%), ductography was the only means of identifying lesions to be resected. Patients who underwent ductography-guided operation (n = 42, 50%) or any surgical procedure including a localization study (n = 66, 78.6%) were significantly more likely than patients who underwent central duct excision alone to have a specific underlying lesion identified (p = 0.045 and p = 0.033, respectively). CONCLUSIONS: Abnormalities on mammography and sonography in patients with nipple discharge should alert physicians to the possibility of a breast cancer diagnosis. In patients with pathologic discharge with normal findings on physical examination and other imaging studies, ductography might be the only means of localizing and resecting breast lesions associated with nipple discharge.

Microcalcification detectability for four mammographic detectors: flat-panel, CCD, CR, and screen/film).

Amorphous silicon/cesium iodide (a-Si:H/CsI:Tl) flat-panel (FP)-based full-field digital mammography systems have recently become commercially available for clinical use. Some investigations on physical properties and imaging characteristics of these types of detectors have been conducted and reported. In this perception study, a phantom containing simulated microcalcifications (microCs) of various sizes was imaged with four detector systems: a FP system, a small field-of-view charge coupled device (CCD) system, a high resolution computed radiography (CR) system, and a conventional mammography screen/film (SF) system. The images were reviewed by mammographers as well as nonradiologist participants. Scores reflecting confidence ratings were given and recorded for each detection task. The results were used to determine the average confidence-rating scores for the four imaging systems. Receiver operating characteristics (ROC) analysis was also performed to evaluate and compare the overall detection accuracy for the four detector systems. For calcifications of 125-140 microm in size, the FP system was found to have the best performance with the highest confidence-rating scores and the greatest detection accuracy (Az = 0.9) in the ROC analysis. The SF system was ranked second while the CCD system outperformed the CR system. The p values obtained by applying a Student t-test to the results of the ROC analysis indicate that the differences between any two systems are statistically significant (p<0.005). Differences in microC detectability for the large (150-160 microm) and small (112-125 microm) size microC groups showed a wider range of p values (not all p values are smaller than 0.005, ranging from 0.6 to <0.001) compared to the p values obtained for the medium (125-140 microm) size microC group. Using the p values to assess the statistical significance, the use of the average confidence-rating scores was not as significant as the use of the ROC analysis p value for p value.

Computer-aided diagnosis in breast magnetic resonance imaging.

In this paper, we review the role played by breast magnetic resonance imaging in the detection and diagnosis of breast cancer. This is followed by a discussion of clinical decision support systems in medicine and their contributions in breast magnetic resonance imaging interpretation. We conclude by discussing the future of computer-aided diagnosis in breast magnetic resonance imaging.

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.