Tamara Miner Haygood

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.

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.

Central Venous Line Placement in the Superior Vena Cava and the Azygos Vein: Differentiation on Posteroanterior Chest Radiographs

OBJECTIVE The purpose of this study was to determine, first, the accuracy with which radiologists reading posteroanterior chest radiographs differentiate whether a central venous line is in the superior vena cava or the azygos vein and, second, the circumstances in which radiologists may omit the lateral view to determine the position of a central venous line. MATERIALS AND METHODS Twenty-four radiologists evaluated 60 posteroanterior chest radiographs to determine the position of a central venous line in the superior vena cava or azygos vein. Investigators evaluated the appearance of the central venous lines to refine rules for determining central venous line position on a frontal radiograph and omitting the lateral view. RESULTS The accuracy of posteroanterior radiography for determining central venous line position was 90% at one study location and 85.5% at the other. No central venous line in the azygos vein extended more than 10.9 mm caudal to the cephalic edge of the right main bronchus. No central venous line in the superior vena cava had a down-the-barrel or curved appearance at the caudal edge. CONCLUSION For central venous lines extending at least 15 mm caudal to the cephalic edge of the right main bronchus and having no down-the-barrel or curved caudal appearance, categorization was nearly 100% accurate. Therefore, if desired to save radiation exposure and cost, it may be feasible to omit lateral views in radiography of patients with central venous lines extending at least 15 mm caudal to the cephalic edge of the right main bronchus in whom the caudal edge does not have a down-the-barrel or curved appearance.

Pilot trial of bone-targeted therapy combining zoledronate with fluvastatin or atorvastatin for patients with metastatic renal cell carcinoma.

BACKGROUND The biological rationale for this study came from the observation that bisphosphonates and statins affect bone metastasis in different ways and thus combination therapy may provide synergistic benefit. This pilot trial evaluated the efficacy and safety of combining a bisphosphonate and a statin in patients with RCC metastatic to bone. METHODS Patients with RCC and bone metastasis received zoledronate and fluvastatin or atorvastatin. Patients were monitored clinically and by imaging for skeletal events. Concentrations of the bone resorption markers deoxypyridinoline (DPD) and N-telopeptide (NTX) and the bone formation marker bone-specific alkaline phosphatase (BSAP) were monitored for changes during treatment. RESULTS Eleven patients were enrolled and followed for a median of 6 months. The median time to first skeletal-related event for all patients was 9.0 months. Seven (63%) patients experienced skeletal events with a median time to first skeletal-related event of 4.0 months (range, 3-18 months); 4 patients (36%) experiences no skeletal events for a median of 12 months of follow-up (range, 2-28 months); 4 patients (36%) demonstrated treatment responses with development of sclerosis in lytic bone lesions. Differences in the median changes in biomarker levels between patients who had skeletal events and those who did not were statistically significant for DPD and NTX (P = .03 and .01, respectively) but not for BSAP (P = .4). The regimen was well tolerated, with few adverse reactions related to the study drugs. CONCLUSION Although the use of bone-targeting therapy combining zoledronate and fluvastatin or atorvastatin affected certain bone biomarkers and provided bone response in several patients with RCC and bone metastasis, we could not demonstrate a statistically significant improvement in time to skeletal events.

A half-second glimpse often lets radiologists identify breast cancer cases even when viewing the mammogram of the opposite breast

Significance Discovering characteristics of a signal that indicates to medical experts the presence of cancer in a noninvasive screening technique in a blink of an eye has implications for improving cancer detection. Here we report two surprising facts about this signal. First, it is much stronger in the high spatial frequencies (fine detail) than in the low frequencies. Second, it is widely distributed, with signal being present well away from the actual visible locus of disease even in the breast contralateral to visible signs of disease. Although this signal is not, in itself, definitive, it has the potential to be used in automated aids to medical screening and incorporated into training protocols for medical experts, speeding up and improving cancer detection. Humans are very adept at extracting the “gist” of a scene in a fraction of a second. We have found that radiologists can discriminate normal from abnormal mammograms at above-chance levels after a half-second viewing (d′ ∼ 1) but are at chance in localizing the abnormality. This pattern of results suggests that they are detecting a global signal of abnormality. What are the stimulus properties that might support this ability? We investigated the nature of the gist signal in four experiments by asking radiologists to make detection and localization responses about briefly presented mammograms in which the spatial frequency, symmetry, and/or size of the images was manipulated. We show that the signal is stronger in the higher spatial frequencies. Performance does not depend on detection of breaks in the normal symmetry of left and right breasts. Moreover, above-chance classification is possible using images from the normal breast of a patient with overt signs of cancer only in the other breast. Some signal is present in the portions of the parenchyma (breast tissue) that do not contain a lesion or that are in the contralateral breast. This signal does not appear to be a simple assessment of breast density but rather the detection of the abnormal gist may be based on a widely distributed image statistic, learned by experts. The finding that a global signal, related to disease, can be detected in parenchyma that does not contain a lesion has implications for improving breast cancer detection.

Challenges in Mammography: Part 1, Artifacts in Digital Mammography

OBJECTIVE Early detection of breast cancer is directly related to the radiologists 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.

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.

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.

Comparison of half-dose and full-dose gadolinium MR contrast on the enhancement of bone and soft tissue tumors

ObjectiveTo evaluate the effect of half-dose intravenous gadolinium contrast on the enhancement of bone and soft tissue tumors.Materials and methodsThis study is HIPAA compliant and informed consent was waived by the institutional review board. An institutional database search was performed over a 1-year period for patients with full- and half-dose MR examinations performed for musculoskeletal oncologic indications. Examination pairs that were identical with regard to field strength and presence or absence of fat saturation were included, resulting in 29 paired examinations. When multiple, the lesion that was best delineated and enhanced well on the first examination in the pair was chosen, yielding 17 bone and 12 soft tissue. Five musculoskeletal radiologists blinded to dosages were asked to assess for a difference in enhancement when comparing the lesion on both examinations and to rate the degree of difference on a three-point scale. They were also asked to identify the examination on which the lesion enhanced less (tallied as low dose). Results were analyzed with the exact binomial test.ResultsThe readers perceived an enhancement difference in 41% (59/145) of studies (p = 0.03) and the majority were rated as “mild” (66%, 39/59). The readers did not accurately identify the low-dose examinations (54% correctly identified, 32/59, p = 0.60).ConclusionsHalf-dose gadolinium enhancement of lesions could not be accurately distinguished from full-dose enhancement upon review of the same lesion imaged at both concentrations.

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.