The economics of mammography quality assurance.
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Hospital Departments↗
Biomedical subjects
C Kimme-Smith
Publications and source records attributed to C Kimme-Smith.
Breast sonography: technique, equipment, and normal anatomy.
In order to interpret breast sonograms successfully, it is necessary to understand the technical factors that affect the image. It is especially important to be aware of the effects of focal zone, power, time gain compensation, and gray scale selection on cyst/solid differentiation, the primary indication for breast sonography. Adequate breast examinations can be performed with either high-frequency automated whole-breast ultrasound units or hand-held instruments with a transducer operating at 5 MHz or greater frequency, and with a depth of focus of no more than 3 cm. Familiarity with the normal breast sonogram, including the variations in the relative amounts of parenchyma, connective tissue, and fat that occur with increasing age and parity, is essential for the identification, characterization, and localization of abnormalities.
Breast↗
Ultrasound breast examination of asymptomatic patients with normal but radiodense mammograms.
Of 1757 consecutive women patients examined with ultrasound (US) between 1983-1986, 796 patients were asymptomatic, had no masses on their mammograms, and were scanned with whole breast US because their breasts were radiodense on mammography. Combinations of automated and real-time hand-held equipment, ranging in frequency from 3.9 MHz to 10 MHz. were used. Of the 796 examinations, 71.5%(569) were normal, 23.5%(187) disclosed cysts, and 4.3%(40) revealed solid masses. Four masses were biopsied, yielding one malignancy, two fibroadenomas and one normal breast tissue. All but 4 of the remaining 36 asymptomatic women with solid masses had a follow-up period of at least 1 year. In the authors' opinion, this low yield of one breast cancer in 796 asymptomatic women implies that whole breast US is of little value (in terms of breast cancer detection) in breasts that are radiodense but otherwise negative on mammography.
Adolescent↗
Ultrasound artifacts affecting the diagnosis of breast masses.
An investigation of the outcome of over 1600 breast ultrasound examinations revealed a number of scanning artifacts. Artifactual echoes in cysts resulted from inappropriate scanning factors, including focal zone placement, gain, TGC, and gray scale, and from partial volume effect. The absence of a sign suspicious for carcinoma, posterior shadowing to a solid mass, resulted from faulty focal zone placement, or from the mass resting on chest wall tissue. Pathology was sometimes simulated by postsurgical scars, ducts, and benign calcifications. Corrective procedures to alleviate the various scanning artifacts are recommended.
Breast↗
The technology of mammography. Misunderstood and underutilized.
This article reviews milestones in the technological development of mammography since 1970. Mammography is particularly underutilized as a screening procedure for breast cancer and the reasons for its continued inappropriate and under use are explored. Although there are some known barriers to increased utilization among the female adult population, the majority of barriers reside within the domain of referring physicians. Remedies to address the low referral rates for screening mammography are outlined for federal agencies, radiology groups, mammography equipment companies, medical schools, and philanthropic groups. Until the developers of technological procedures such as mammography appreciate that the application of a technology and its appropriate utilization by professionals and the public are important to consider when the technology is developed, utilization rates may not do justice to the technology's potential.
Adult↗
High frequency breast ultrasound. Hand-held versus automated units; examination for palpable mass versus screening.
Four hundred forty-five patients had one or more breast ultrasound examinations with equipment from six manufacturers, operating at 5, 7.5, or 10 MHz. Two hundred seven patients were examined by both automated and hand-held units. In revealing cysts and solid masses, the automated and hand-held units performed nearly identically. Of 198 patients who had screening mammograms, ultrasound evaluation revealed that 85 (43%) had cysts, while 32 (16%) had solid masses. Of the 207 patients who had diagnostic mammograms for a palpable mass, 63 (30.4%) had cysts, while an equal number had solid masses. Of 45 solid masses from both groups that were imaged and biopsied, all 15 that were malignant were palpable. No nonpalpable malignancies were found by ultrasound alone.
Adolescent↗
Automated and hand-held breast US: effect on patient management.
Breast ultrasound (US) was performed, with either an automated or a hand-held unit or both, on 1,212 patients. Of 612 asymptomatic patients, 118 (19.3%) had solitary cysts; ten (1.6%), multiple cysts; and 29 (4.7%), benign masses; however, US depicted only one (0.2%) nonpalpable mammographically undetected carcinoma. In 513 patients with palpable masses (n = 396) and with mammographically detected masses (n = 117), US was useful in avoiding an unnecessary biopsy in 113 (22.0%), leading to aspiration of a cyst in 26 (5.1%), monitoring multiple cysts in 31 (6.0%), avoiding aspiration of a solid mass in 65 (12.7%), supporting biopsy of an equivocal solid mass in 91 (17.7%), and demonstrating a nonpalpable mammographically detected carcinoma in six (1.2%). In 224 patients with either palpable or mammographically visible masses who underwent both methods of US, the 4.5-MHz or 3.9-MHz automated unit depicted the abnormality in 119 (53.1%) and the 7.5-MHz hand-held unit, in 171 (76.3%). Of 18 cancers evaluated with both methods, all were detected with the hand-held unit and only 12 were seen with the automated unit.
Adolescent↗
Mammographic dual-screen-dual-emulsion-film combination: visibility of simulated microcalcifications and effect on image contrast.
Three test objects simulating different mammographic problems were imaged with a new low-dose dual-screen-dual-emulsion-film combination and a standard screen film combination, with and without a moving grid, at 28 and 32 kVp, and with 0.3- and 0.5-mm focal spots. The new combination reduced exposure by 50%, but it failed to equal the other combination in the depiction of simulated microcalcifications, even when a different brand of film-processing chemicals was used. Compared with the standard screen-film combination exposed without a grid, the new combination exposed with a grid resulted in a superior image of dense parenchyma without an increase in dose. Furthermore, when the exposure time was decreased by 25% (rather than 50%), dense breasts were imaged with greater penetration by the new combination. A clinical trial of the new combination in 200 patients showed prominent quantum mottle and reduced contrast in regions of dense parenchyma. In addition, the skin and subcutaneous tissue were often poorly depicted with both standard and high-intensity illumination.
Breast Neoplasms↗
Evaluation of radiation dose, focal spot, and automatic exposure of newer film-screen mammography units.
Fifteen recently introduced mammographic units representing eight different models and manufacturers were evaluated to see whether the equipment performance equaled claims made by the manufacturers. Focal-spot size was measured by pinhole and slit methods. Eight automatic exposure control systems on five models were tested by measuring the optical density produced by imaging at 28 and 30 kVp, with and without a grid and with test objects of varying thicknesses of BR12 epoxy material. Comparable mean glandular dose for a 4-cm-thick BR12 test object was measured for 13 of the units under manual or automatic exposures. Nominal focal-spot size was larger than stated for six of the 15 large focal spots and for seven of the 12 microfocal spots. Comparable doses under automatic exposure control varied more than 100% between units from different manufacturers, while the doses of units from the same manufacturer varied less than 20%. Automatic exposure control systems were operational in eight of the 15 units, but four of these eight were found to be out of calibration. There are considerable performance variations that need to be evaluated before acceptance and use of new mammographic equipment.
Breast↗
A modified harlequin stain for cell kinetics.
Lymphocytes cultured with 4 X 10(-4) M bromodeoxyuridine (BrdU) and stained by the harlequin procedure show wide variations in the colour and texture of their interphase nuclei. We demonstrate that we are able, by inspection, to identify four sets of nuclei: small dark nuclei (D) in cells that have not transformed in response to mitogenic stimulation; red nuclei (R) in transformed cells that have not synthesized DNA in culture; speckled nuclei (S)--red speckles on a bluish background--in cells that are synthesizing DNA for the first time in culture; blue nuclei (B) in cells that have completed one or more cycles of DNA synthesis. By using this modified harlequin stain to score the fraction of proliferating cells, and using the modified or conventional harlequin stain to determine the relative frequencies of mitotic cells in the first, second, or later divisions, we are able to estimate the fraction of lymphocytes in the original blood sample that can divide in culture. In addition, we show that the technique lends itself to automation. For this we have digitized black and white video images of the cells and extracted features based on the distribution of optical densities in the nuclei. Discriminant analysis carried out on these descriptors resulted in the correct classification of the three major groups R, S and B with an accuracy of 80.3%, 58.5% and 85.1%, respectively.
Adult↗
Calibration of automated water-path breast ultrasound scanners.
Simple calibration procedures that can be performed by a technologist for Ausonics, Labsonics, and Technicare automated water-path breast scanners are described. These procedures can be applied to each unit to test transducer resolution, slice thickness, and sensitivity. Quality control has ensured consistent and reliable operation of these units and has helped technologists to describe specific problems to service engineers.
Breast Diseases↗
Breast imaging. State-of-the-art.
The underlying goal of all breast imaging procedures is the detection of cancer. X-ray mammography places greatest emphasis on the disclosure of early, nonpalpable, curable cancer. Diagnostic ultrasonography stresses the differentiation of benign cysts from diagnostically indeterminate solid masses that require biopsy. Evolving experimental procedures such as transillumination light-scanning and magnetic resonance imaging currently are undergoing preliminary evaluation. An older procedure, thermography, seems to operate at a high level of effectiveness only for advanced cancer. Since x-ray mammography is the technique that has proven most successful in detecting early breast cancer, it is the standard to which all imaging alternatives must be compared.
Adult↗
Whole-breast US imaging: four year follow-up.
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Breast Neoplasms↗
Ultrasound mammography: effects of focal zone placement.
In order to avoid serious pitfalls in the diagnosis of breast masses by sonography, it is important to understand the effects of technical factors such as focal zone placement and time gain compensation.
Breast↗
Renal stone shadowing: an investigation of contributing factors.
A series of in vitro experiments evaluated the effects of intervening tissue, B-mode processing algorithms, stone chemical composition, stone size, and reverberation artifacts on the acoustic shadows of renal stones. Stone size was found to be the most important variable; intervening tissue and focal zone placement also affected imaging. Reverberation artifacts may fill in an acoustic shadow, but can still provide information. The survey algorithm produced slightly clearer shadows than the static storage algorithm. Gray-scale map changes, increased power, and chemical composition of calculi did not affect shadowing.
Animals↗
Measurement accuracy of sonographic sector scanners.
Discrepancies identified in anatomic size measurements in clinical obstetric sonographic studies prompted a study of the accuracy of measurements obtained from sonographic mechanical sector scanners. There were large variations in equipment calibration of the size of the sector scan angle among six clinical sonographic units from four manufacturers, causing transverse measurements to vary from 47% (high) to 9% (low), compared with the true size of a cylindrical plastic phantom. Depth measurements, parallel to the direction of sound penetration, are only velocity dependent and were accurate to within 6%. Transverse size measurements made using mechanical sector scanners should be suspect unless the calibration has been checked using a phantom test object.
Calibration↗
Gray scale of ultrasound instruments: evaluation using a test object.
B-mode scans of castor oil in a wedge-shaped container provide gray level maps. The relation between the gray levels and the amounts of absorbing medium can be used to measure the effects of electronic gain, transducer characteristics, and the overall gray level performance of different ultrasound systems. We report results from four units and ten transducers for varying scanning depths.
Castor Oil↗
The relative effects of system parameters on texture in gray-scale ultrasonograms.
Texture in B-mode ultrasonography of the abdomen can, in many cases, serve as an important diagnostic tool. Unfortunately, because texture as it is now presented depends on many parameters which are independent of pathology, it is not always a reliable sign. Parameters such as transducer size, center frequency, and bandwidth; B-mode display and storage methods; near and far field wave effects; and the type of intervening tissue all influence the display of texture. We have investigated these parameters of texture through the analysis of computer simulated B-mode ultrasonograms based on in vitro A-line data collected under a variety of circumstances and conditions. A freshly excised bovine pancreas served as the target tissue. Computer generated textured B-mode images, produced with different gray-scale and scan converter storage algorithms, were evaluated by a panel of six radiologists who individually divided sixty images into groups of images with similar texture. These evaluations were mapped into a six feature hyperspace with each axis representing a particular parameter. By applying a variation of the principal components transformation, each parameter could be ranked according to its effect on texture. We found that the type of gray-level preprocessing map had the most effect on texture; intervening tissue and transducer variations had intermediate effects. So long as the target distance did not exceed the focal length of the transducer, the distance between the transducer and the target tissues had the least effect on texture.
Animals↗