Automatic segmentation of mammographic density.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate a completely automatic method, based on Kittler's optimal threshold, to estimate breast density by using the mammographers' definition. MATERIALS AND METHODS: Thirty-two normal, right-craniocaudal-view mammograms of women aged 37-86 years were digitized. The whole breast area was segmented by using Kittler's optimal threshold procedure, and the dense portions were then segmented by using a modified version of Kittler's method. Segmentation results were validated by three independent mammographers who provided a signed percentage (in steps of 5%) to indicate the difference between their own visual estimation of the dense portions and the results obtained with the algorithm. The difference between the algorithm measurements and the mammographers' measurements was compared to the interobserver differences. RESULTS: A high correlation was found between the algorithm measured density and the mammographers' measurements. Spearman correlations ranged from 0.92 to 0.95 (P < .001). Algorithm-measured density differed from the mammographers' measurements by an average of 6.9% (ie, average of the absolute differences). In contrast, mammographers' measurements differed between themselves by an average of 5.4%. CONCLUSION: The difference between density as measured with the algorithm and as measured by the mammographers is similar to the differences observed between mammographers. This algorithm could be useful in providing clinically accurate estimates of breast density.

Comparing the performance of mammographic enhancement algorithms: a preference study.

OBJECTIVE: The objective of this study was to compare the performance of four image enhancement algorithms on secondarily digitized (i.e., digitized from film) mammograms containing masses and microcalcifications of known pathology in a clinical soft-copy display setting. MATERIALS AND METHODS: Four different image processing algorithms (adaptive unsharp masking, contrast-limited adaptive histogram equalization, adaptive neighborhood contrast enhancement, and wavelet-based enhancement) were applied to one image of secondarily digitized mammograms of forty cases (10 each of benign and malignant masses and 10 each of benign and malignant microcalcifications). The four enhanced images and the one unenhanced image were displayed randomly across three high-resolution monitors. Four expert mammographers ranked the unenhanced and the four enhanced images from 1 (best) to 5 (worst). RESULTS: For microcalcifications, the adaptive neighborhood contrast enhancement algorithm was the most preferred in 49% of the interpretations, the wavelet-based enhancement in 28%, and the unenhanced image in 13%. For masses, the unenhanced image was the most preferred in 58% of cases, followed by the unsharp masking algorithm (28%). CONCLUSION: Appropriate image enhancement improves the visibility of microcalcifications. Among the different algorithms, the adaptive neighborhood contrast enhancement algorithm was preferred most often. For masses, no significant improvement was observed with any of these image processing approaches compared with the unenhanced image. Different image processing approaches may need to be used, depending on the type of lesion. This study has implications for the practice of digital mammography.

Clinical evaluation of wavelet-compressed digitized screen-film mammography.

RATIONALE AND OBJECTIVES: The authors compared diagnostic accuracy and callback rates with conventional screen-film mammograms and wavelet-compressed digitized images. MATERIALS AND METHODS: Sixty sets of mammograms (four views per case) were digitized at a spatial resolution of 100 microm. The images were wavelet compressed to a mean compression ratio of 8:1 and reviewed by three mammographers. Five regions were evaluated in each breast. Suspicion of malignancy was graded on a scale of 0% to 100%, and receiver operating characteristic (ROC) analysis was performed. Callback rates were calculated by using the American College of Radiology's Breast Imaging Reporting and Data System lexicon scale. RESULTS: The mean diagnostic accuracy with compressed and conventional images was 0.832 and 0.860, respectively. The upper 95% confidence bound for the difference in ROC areas was 0.061. The mean false-positive rate at a fixed sensitivity of 0.90 was 0.041 for compressed images and 0.059 for conventional images. The mean callback rates for normal, benign, and malignant regions were 0.023, 0.305, and 0.677, respectively, for compressed images and 0.036, 0.447, and 0.750, respectively, for conventional images. The upper 95% confidence bound for the (absolute) differences in callback rates was 0.012 for normal regions, 0.163 for benign regions, and 0.138 for malignant regions. CONCLUSION: Diagnostic accuracies were equivalent for both compressed and conventional images. The mean false-positive rate at fixed sensitivity was much better with the compressed images. However, the callback rates for malignant lesions were lower when the compressed images were used.

How new technology is changing mammography and breast cancer management.

Breast-imaging technology has improved in ways that allow one not only to detect breast cancer earlier, but also to distinguish benign from malignant lesions better. These capabilities are influencing the approach to breast cancer. We review current trends and issues for the non-radiologist.

Film-screen versus digitized mammography: assessment of clinical equivalence.

OBJECTIVE: The purpose of this study was to determine whether diagnostic accuracy and callback rates using digitized film images are equivalent to those using film-screen mammograms. MATERIALS AND METHODS: Sixty sets of mammograms (four views per case) were digitized at a spatial resolution of 100 microm. The images were reviewed by seven mammographers. Five regions were evaluated in each breast. Each region was scored on a scale of 0 100% for suspicion of malignancy, and a receiver operating characteristic analysis was performed. Callback rates were calculated using a published lexicon scale. RESULTS: The observers' mean diagnostic accuracies using films and digitized images were 0.872 and 0.848, respectively. The upper 95% confidence boundary on the difference in accuracy was 0.066. The mean callback rate for normal, benign, and malignant areas using films versus digitized images was 0.048 versus 0.055, 0.498 versus 0.441, and 0.786 versus 0.737, respectively. The upper 95% confidence boundary for the absolute difference in callback rates was 0.037, 0.026, and 0.130 for normal, benign, and malignant areas, respectively. CONCLUSION: The diagnostic accuracies of the digitized images and films were similar; however, an increase in callback rates of 0.037 (i.e., upper 95% confidence boundary) for normal results and a reduction in the callback rates of 0.130 for malignant lesions is important. The use of digitized film images, at a spatial resolution of 100 microm, may compromise patient treatment in clinical practice.

Quantitative analysis of breast parenchymal density: correlation with women's age.

RATIONALE AND OBJECTIVES: The authors evaluated the relationship between a woman's breast parenchymal density and her age by means of a quantitative method for measuring density from digitized mammograms. MATERIALS AND METHODS: The percentage of the breast considered to be dense was evaluated from mammograms of 50 women stratified by age. Quantitative analysis based on the computer segmentation of tissue in digitized mammograms was performed by three expert mammographers. The results of this analysis were compared with results from a review of the film mammograms by three expert mammographers. RESULTS: A slight decrease in the percentage of breast considered to be dense with increased age was observed. The average difference in the percentage of dense breast tissue between the youngest and the oldest age groups was 6.4% based on the digital review and 14.6% based on the film review. Within each age group, the total variability was on the order of 75%. CONCLUSION: The difference in mean magnitude between the youngest and oldest age groups was small and may not be clinically important. The variability within an age group was large, which suggests that age is not a reliable indicator of percentage of dense breast tissue.

Stereotactic breast biopsy: a less-invasive option.

Until recently, a woman with a nonpalpable lesion detected on mammography had to undergo the emotional and physical trauma of surgical excision. However, a new technique, percutaneous core needle biopsy, guided by digital three-dimensional x-ray imaging, offers a reasonable alternative to standard surgical biopsy. This method produces no pseudolesions, subjects the patient to less physical and emotional trauma, is done on an outpatient basis with local anesthesia, and costs far less than the surgical method.

Quantitative classification of breast tumors in digitized mammograms.

The goal of this study was to develop a technique to distinguish benign and malignant breast lesions in secondarily digitized mammograms. A set of 51 mammograms (two views/patient) containing lesions of known pathology were evaluated using six different morphological descriptors: circularity, mu R/sigma R (where mu R = mean radial distance of tumor boundary, sigma R = standard deviation); compactness, P2/A (where P = perimeter length of tumor boundary and A = area of the tumor); normalized moment classifier; fractal dimension; and a tumor boundary roughness (TBR) measurement (the number of angles in the tumor boundary with more than one boundary point divided by the total number of angles in the boundary). The lesion was segmented from the surrounding background using an adaptive region growing technique. Ninety-seven percent of the lesions were segmented using this approach. An ROC analysis was performed for each parameter and the results of this analysis were compared to each other and to those obtained from a subjective review by two board-certified radiologists who specialize in mammography. The results of the analysis indicate that all six parameters are diagnostic for malignancy with areas under their ROC curves ranging from 0.759 to 0.928. We observed a trend towards increased specificity at low false-negative rates (0.01 and 0.001) with the TBR measurement. Additionally, the diagnostic accuracy of a classification model based on this parameter was similar to that of the subjective reviewers.

Gastrointestinal radiology: current indications and referral patterns.

To determine the current indications and referral patterns for routine gastrointestinal radiology examinations, 1000 consecutive patients were prospectively analyzed. The following specialties were the largest sources of referral: general internal medicine (38%), gastroenterology (21%), and general and colorectal surgery (17%). Referrals from gastroenterologists were weighted toward areas not well evaluated by endoscopy, such as suspected small bowel disease. The major indications for upper gastrointestinal (GI) examinations were dysphagia and swallowing disorders (32%), hiatus hernia/reflux (14%), and ulcer (14%). Small bowel series were predominantly performed for inflammatory bowel disease (37%), obstruction (25%), and occult blood loss (18%). The majority of combined upper GI/small bowel studies were performed for indications primarily relating to the small bowel. Forty percent of barium enemas were performed for detection of neoplasms and polyps, with pain/irritable colon (14%) and exclusion of leak (14%) the next most common indications. Traditional indications, such as peptic ulcer disease and neoplastic disease, continue to be sources of referral for gastrointestinal radiology. However, more specialized applications, particularly in areas not well suited to endoscopy, such as swallowing disorders, inflammatory disease of the small bowel, and evaluation of surgical anastomoses, are also being commonly used. The changing indications, along with the previously documented decreased volume of gastrointestinal radiologic procedures, should be kept in mind when planning a radiology resident educational curriculum.

Abdominal lymphadenopathy: spectrum of CT findings.

Many malignant processes cause abdominal lymphadenopathy, and computed tomography (CT) has become the primary modality for its detection. Diagnosis of lymphadenopathy is facilitated by optimal imaging techniques and a knowledge of the various nodal chains, their complex interconnections, and preferential pathways of spread. Optimal techniques include imaging after oral administration of adequate amounts of barium suspension and dynamic scanning after intravenous administration of contrast material with an infusion pump. Although such techniques help prevent misdiagnoses due to normal and anomalous vascular structures, other benign diseases can mimic the CT appearance of malignant lymphadenopathy. The authors emphasize a regional approach for the diagnosis of lymphadenopathy, according to the groupings of retrocrural, retroperitoneal, gastrohepatic ligament, porta hepatis, celiac and superior mesenteric artery, pancreaticoduodenal, perisplenic, mesenteric, and pelvic lymph nodes. Lymphadenopathy is defined as retrocrural nodes greater than 6 mm in short axis, upper abdominal nodes greater than 10 mm, and pelvic nodes greater than 15 mm.

Breast specimen radiography: evaluation of a compression device.

The irregular shape and uneven tissue thickness of excised breast specimens makes radiographic evaluation difficult, especially when calcifications are not present. Xeroradiographs before and after compression of 20 separate excised breast specimens were compared, and 17 of the same specimens were compared after compression combined with immersion in water. Specimen compression improved visibility of the lesion on average in 88% of cases, and visibility was equal in 12%. Combined compression/immersion further improved visibility of the lesion on average in 37% of cases. More significantly, evaluation of the compressed specimen led to a change in interpretation of the radiographs in 45% of cases. Compression of the specimen in specimen radiography is recommended in all cases in which pre-biopsy localization is performed.

Intracranial hemorrhage and neurodevelopmental outcome at one year in infants weighing 1200 grams or less. Prognostic significance of ventriculomegaly at term gestational age.

Seventy-five surviving infants weighting 1200 g or less at birth were followed up longitudinally, employing real-time ultrasonographic examination of the brain from birth to term corrected gestational age. Evaluations using the Milani-Comparetti Motor Developmental Screening Test and developmental testing using the Bayley Scales of Infant Development were performed at 4, 8, and 12 months corrected age. Thirty-five (46.7%) of the infants were diagnosed to have intracranial hemorrhage (ICH). These infants were significantly smaller and lighter and were mechanically ventilated close to five times longer than infants without ICH. ICH was predictive of poorer developmental outcome through the first postnatal year. ICH infants had significantly lower Bayley motor scores at both 4 and 12 months. Sixteen of the 20 who scored less than 84 on one or both of the Bayley Scales at one year had a history of ICH. When infants with hemorrhage and normal ventricles at term (ICH-no VM) were compared to infants with hemorrhage and ventriculomegaly at term (ICH-VM), the poorest motor outcome was seen in the ICH-VM group. Only the ICH-VM group showed motor performance significantly poorer than the non-ICH group at 12 months of age. Regardless of severity of hemorrhage, the data suggested an added risk for poorer developmental outcome in ICH survivors who had ventriculomegaly or abnormal periventricular morphology at term. Thus, intracranial hemorrhage per se indicates significantly greater risk of short-term motor sequelae continuing through the first four postnatal months, but persistently abnormal ventricles serve as a more significant "marker" of risk for longer term neuromotor delays at one year corrected age.(ABSTRACT TRUNCATED AT 250 WORDS)

Volume and planar gated cardiac magnetic resonance imaging: a correlative study of normal anatomy with thallium-201 SPECT and cadaver sections.

Magnetic resonance (MR) gated cardiac imaging was performed in ten subjects using a prototype 0.15-T resistive magnet imaging system. Volume and planar imaging techniques utilizing saturation recovery, proton Tl-weighted relaxation time pulse sequences produced images of the heart and great vessels with exquisite anatomic detail that showed excellent correlation with cadaver sections of the heart. The left ventricular myocardial segments also showed excellent correlation with the thallium-201 cardiac single photon emission computed tomography images. Volume acquisition allowed postprocessing selection of tomographic sections in various orientations to optimize visualization of a particular structure of interest. The excellent spatial and contrast resolution afforded by MR volume imaging, which does not involve the use of ionizing radiation and iodinated contrast material, should assure it a significant role in the diagnostic assessment of the cardiovascular system.

CT of pseudomyxoma peritonei: case report.

Pseudomyxoma peritonei is an uncommon disorder, which is usually the sequelae of mucocele of the appendix or mucinous ovarian cystadenocarcinoma. The characteristic CT findings of massive ascites, loculated fluid collections, hepatic and mesenteric scalloping caused by low attenuation tumor masses, without lymphadenopathy and in the presence of intrinsically normal viscera strongly suggest the diagnosis.

Digital subtraction angiography: principles, techniques, and applications.

Digital subtraction angiography is a safe, rapid, cost-saving procedure that can be performed on an outpatient basis to obtain information comparable to that obtained with conventional angiography. Recent technological developments have allowed greater contrast sensitivity, making DSA a feasible alternative to conventional angiography. Problems with DSA result mainly from patient motion. The overall accuracy of DSA ranges from 97% in the carotids to about 90% in evaluation of main renal artery stenosis. DSA is currently of limited use in evaluation of the pulmonary or coronary arteries.