Quantitative computed tomography for spinal density measurement. Factors affecting precision.

Quantitative computed tomography (QCT) was performed in duplicate on 84 patients to test the short-term precision of the technique. Statistical analysis of the data revealed that precision was not a function of spinal density. It appeared to be worse in osteopenic individuals only when expressed as a percentage. Precision was slightly better in male than in female patients. There is a 90% likelihood that a duplicate measurement will fall within 20 CT units of the first determination in female patients and within ten units in male patients.

Preliminary clinical evaluation of a high-resolution telemammography system.

RATIONALE AND OBJECTIVES: The authors designed, assembled, tested, and clinically evaluated a high-quality, fast, and relatively inexpensive telemammography system. METHODS: The authors designed a telemammography system that uses a high-resolution film digitizer and high data compression (> or = 40:1) to send images over regular telephone lines to a high-resolution laser printer that produces images with the look and feel of the original image and can operate in a hub and spokes mode. The authors then evaluated the system's performance. In a preliminary clinical study, interpretations of the laser-printed system's output of 119 cases were compared with the original interpretations, followed by a review of any clinically significant differences. RESULTS: With the exception of the laser printer, which is a modified off-the-shelf product, all hardware components of the system are commercially available products. The system digitizes (50 microns pixel size), compresses, transmits, receives, decompresses, and prints a 30 MB mammography file in less than 4 minutes. In the clinical study, there were 13 differences (in 13 cases) in the level of concern or recommendations. Seven were found to be clinically insignificant by a third-party review. The remaining six were reviewed by the original interpreter, and three were determined to be significant enough for further action. All were found to result from intra-reader variability rather than differences in visualization of possible abnormalities. CONCLUSIONS: Almost real-time, high-quality telemammography without geographic boundaries is possible with the use of high-level data compression. Telemammography with laser-printed film as the display may make it possible to offer mammographic services in remote locations while using commercially available technology.

Computed radiography versus screen-film mammography in detection of simulated microcalcifications: a receiver operating characteristic study based on phantom images.

RATIONALE AND OBJECTIVES: The authors compare a 43-micron computed radiographic system with a mammographic screen-film system for detection of simulated microcalcifications in an observer-performance study. MATERIALS AND METHODS: The task of detecting microcalcifications was simulated by imaging aluminum wire segments (200-500 microns in length; 100, 125, or 150 microns in diameter) that overlapped with tissue background structures produced by beef brisket. A total of 288 such simulations were generated and examined with both computed radiography and conventional screen-film mammography techniques. Computed radiography was performed with high-resolution plates, a 43-micron image reader, and a 43-micron laser film printer. Computed radiographic images were printed with simple contrast enhancement and compared with screen-film images in a receiver operating characteristic study in which experienced readers detected and scored the simulated microcalcifications. Observer performance was quantitated and compared by computing the area under the receiver operating characteristic curve. RESULTS: Although the resolution of the computed radiography system was better than that of commercial systems, it fell short of that of screen-film systems. For the 100-micron microcalcifications, the difference in the average area under the curve was not statistically significant, but it was significant for the larger simulated microcalcifications: the average area under the curve was 0.58 for computed radiography versus 0.76 for screen-film imaging for the 125-micron microcalcifications and 0.83 versus 1.00, respectively, for the 150-micron microcalcifications. CONCLUSION: Observer performance in the detection of small simulated microcalcifications (100-150 microns in diameter) is better with screen-film images than with high-resolution computed radiographic images.

Breast masses in the augmentation mammaplasty patient: the role of ultrasound.

The detection and evaluation of breast parenchymal abnormalities in the presence of a radiodense implant are often difficult with standard techniques of physical examination and mammography. Breast lesions can be obscured on one or both views by the radiodense implant or concealed within the dense tissue at the prosthesis-breast tissue interface. We investigated the role of ultrasound as an adjunct to mammographic special views, including posterior displacement (Eklund et al.), in previously augmented patients who presented with a clinically palpable mass. The records of 125 consecutive breast augmentation patients seen by us over a 4-year period were retrospectively reviewed. Twenty-six patients presented with a palpable breast abnormality. All 26 patients underwent diagnostic mammograms and sonograms. Findings included 8 parenchymal lesions (4 cysts, 2 fibroadenomas, 1 seroma, 1 breast carcinoma), 8 implant-related irregularities (4 ruptures, 3 bulges, and 1 valve), and normal fibroglandular tissue in 10 patients. Mammography yielded a convincing diagnosis in 7 of 26 patients, whereas ultrasound characterized the abnormality in every case. Ultrasound is a useful adjunct to mammography in evaluating palpable breast abnormalities in the breast augmentation patient. It offers improved visualization of the breast tissue-prosthesis interface, and it is helpful in distinguishing breast parenchymal lesions from palpable irregularities of the implant.

Evaluation of multiplanar reconstruction in CT recognition of lumbar disk disease.

Axial computed tomographic (CT) images were compared with sagittal and coronal reformations and myelograms in 60 patients to evaluate the diagnostic usefulness of multiplanar reconstructions for the recognition of lumbar disk disease. The axial CT scans were most sensitive and specific. The sagittal scans were helpful in evaluating the neural foramina, the size of the disk bulge into the spinal canal, especially at L5-S1, and patients with spondylolisthesis. The coronal images were the least informative, although they contributed to the evaluation of lumbar nerve roots. The myelograms and the sagittal images were equally useful in the detection of herniated disk, but axial scans were superior to either. It was concluded that reformatted sagittal and coronal images are not required if all axial images are normal. However, when uncertainty exists or complex anatomy is being evaluated, reformatted images may be helpful, particularly for reassurance.

Silicone implant rupture: detection with US.

The authors evaluated the ability of ultrasound (US) in detection of silicone implant ruptures and compared US detection with that of mammography and physical examination in 22 women with 29 sites of implant leakage. On sonograms, leaks were evident from a highly echogenic pattern of scattered and reverberating echoes with loss of detail posterior to the echogenic area. The area appears as a "snowstorm" and has a well-defined anterior margin but a poorly defined posterior margin. Twenty-five sites in 19 women were surgically confirmed. Mammograms obtained with various views and sonograms were available for comparison in 20 of 25 surgically confirmed leaks. Of all 29 leaks, 14 were detected at physical examination as palpable masses. Six of these 20 leaks were not detected with mammography. With US, only one leak was not detected. US allowed more accurate prediction of the extent of free silicone in the breast and enabled detection of silicone within axillary nodes. Recognition of the characteristic highly echogenic sonographic appearance of microglobules of free silicone in the soft tissues can improve detection of implant rupture.

Augmentation mammoplasty: normal and abnormal findings with mammography and US.

A retrospective review of 133 patients who had undergone augmentation mammoplasty (n = 122), reconstructive mammoplasty (n = 10), and silicone injections (n = 1) was undertaken to establish the normal appearance of various types of implants, to establish a range of normal variations (wrinkles, valves, minor bulges), and to recognize true implant complications (collapse of a saline prosthesis, leakage of silicone gel, capsular contracture, capsular calcification, and deformities). The detection and evaluation of breast parenchymal abnormalities in the presence of a radiopaque implant are more difficult, and frequently ultrasound (US) or special mammographic views in conjunction with physical examination are required. Coned-down compression spot views are suggested for asymmetric opacities or ill-defined mammographic masses, and magnification views are recommended for microcalcifications: Both should be obtained with the Eklund implant displacement technique. Tangential or other special views combined with US are best for the evaluation of palpable abnormalities and suspected silicone implant rupture.

Detection of masses and clustered microcalcifications on data compressed mammograms: an observer performance study.

OBJECTIVE: To evaluate observers' ability to detect breast masses and clustered microcalcifications depicted on data compressed mammograms, an observer performance study was performed. MATERIALS AND METHODS: Eight observers assessed 60 mammographic images obtained in six modes, ranging from noncompressed to a maximum data compression level of 101:1. Observers were asked to rate the images on a scale of 0 to 100 for the likelihood of the presence of a mass and also independently for the likelihood of the presence of clustered microcalcifications. In addition, observers were asked to rate their subjective assessment of the quality of each image for the detection of a mass and separately for the detection of microcalcifications. Receiver operating characteristic analyses were performed. RESULTS: The average area under the receiver operating characteristic curve, A(z), for the detection of clustered microcalcifications decreases significantly at the highest data compression level when compared with the noncompressed and two lowest levels of data compression (p < 0.01), and a trend test of the average area under the receiver operating characteristic curve for all observers is statistically significant (p < 0.05). No statistically significant differences among or between any of the data compression level modes for the detection of masses were detected. CONCLUSION: At a high level of mammogram data compression, observer performance was degraded for the detection of clustered microcalcifications. Detection of masses was not affected by the data compression methods and levels used in this study.

The mammographic features of the postlumpectomy, postirradiation breast.

Lumpectomy with radiation therapy is becoming widely accepted as an alternative treatment for breast carcinoma in place of radical mastectomy. This article illustrates the spectrum of mammographic changes seen at various intervals after lumpectomy with irradiation to help the mammographer distinguish postoperative scar from a recurrent carcinoma.

Soft-copy mammographic readings with different computer-assisted detection cuing environments: preliminary findings.

PURPOSE: To assess the performance of radiologists in the detection of masses and microcalcification clusters on digitized mammograms by using different computer-assisted detection (CAD) cuing environments. MATERIALS AND METHODS: Two hundred nine digitized mammograms depicting 57 verified masses and 38 microcalcification clusters in 85 positive and 35 negative cases were interpreted independently by seven radiologists using five display modes. Except for the first mode, for which no CAD results were provided, suspicious regions identified with a CAD scheme were cued in all the other modes by using a combination of two cuing sensitivities (90% and 50%) and two false-positive rates (0.5 and 2.0 per image). A receiver operating characteristic study was performed by using soft-copy images. RESULTS: CAD cuing at 90% sensitivity and a rate of 0.5 false-positive region per image improved observer performance levels significantly (P < .01). As accuracy of CAD cuing decreased so did observer performances (P < .01). Cuing specificity affected mass detection more significantly, while cuing sensitivity affected detection of microcalcification clusters more significantly (P < .01). Reduction of cuing sensitivity and specificity significantly increased false-negative rates in noncued areas (P < .05). Trends were consistent for all observers. CONCLUSION: CAD systems have the potential to significantly improve diagnostic performance in mammography. However, poorly performing schemes could adversely affect observer performance in both cued and noncued areas.

Breast cancer measurements with magnetic resonance imaging, ultrasonography, and mammography.

BACKGROUND: Accurate measurement of the size of breast cancers becomes more important as breast cancer therapy advances. This study reports the accuracy of magnetic resonance imaging (MRI), ultrasonography and mammography for measuring the largest breast cancer diameter in comparison to the pathology measurement. MATERIALS AND METHODS: Fourteen breast cancers were examined in 13 women with MRI, ultrasonography and mammography. The age range was 31-73 (mean 56). Six of the cancers were in premenopausal women. The MRI was performed with the intravenous injection of gadolinium based contrast agent and a three dimensional fast spoiled gradient echo sequence with fat suppression. The largest cancer diameter was measured with each imaging technique and compared to the largest cancer diameter measured at pathology. RESULTS: At pathological examination cancers ranged from 0.6 to 6 cm (mean 2.2) in largest diameter. MRI measurements had the highest correlation coefficient (r = 0.98) and the smallest standard error (0.34). Ultrasonography measurements had a correlation coeffient of r = 0.45 and a standard error of 0.78. Mammography measurements had a correlation coefficient of r = 0.46 and a standard error of 1.04. CONCLUSIONS: MRI was more accurate than ultrasonography and mammography in measuring the largest cancer diameters in this group of women. This was particularly evident for several larger cancers, and a postchemotherapy cancer.