William A. Chilcote

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.

Texture analysis of lesions in breast ultrasound images

We investigate the use of Haralicks texture features and posterior acoustic attenuation descriptors (PAAD) for the characterization of ultrasound (US) breast lesions. 71 lesions (24 cyst, 21 benign solid mass and 26 malignant solid masses) were manually segmented on two-dimensional breast US images. 28 Haralicks descriptors and two PAAD were evaluated on these segmented lesions. Mean of Sum Average, Range of Sum Entropy and the second PAAD best discriminated cysts from noncysts. Range of Correlation and the second PAAD best discriminated solid malignant from benign lesions. Computerized analysis of breast US images can increase the specificity of breast sonography by providing a better characterization of solid lesions.

Computed tomography in renal lymphoma.

The computed tomographic characteristics of 15 cases of renal lymphoma were evaluated. Initially the renal lesions are nodular but become confluent as the tumor progresses. In histiocytic and Hodgkin lymphoma, lesions can have the same attenuation values as normal renal parenchyma on noncontrast scans but less than normal parenchyma after contrast medium administration. Computed tomography is also useful in evaluating prognosis and response to therapy in renal lymphoma. Contrast material should be given if possible for evaluation of these lesions.

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

RATIONALE AND OBJECTIVES The authors evaluated the relationship between a womans 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.

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 Radiologys 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.

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.

Classification of breast lesions based on quantitative measures of tumor morphology

High resolution digitized mammograms were used in the development of a technique to classify breast lesions based on their boundary characteristics. Two different boundary descriptors were used to classify the tumors as benign or malignant: a measure of tumor circularity (/spl mu//sub R///spl sigma//sub R/), and a measure of surface roughness. The surface roughness measurement was calculated as the percentage of angles with multiple boundary points. The greater the percentage of angles with multiple boundary points the more irregularly shaped the boundary. 94% of the tumors were automatically segmented to produce boundaries consistent with an outline drawn by an expert reviewer. A classification model which includes both descriptors was diagnostic with an estimated area under the ROC curve of 0.94 (se=0.04).

Texture descriptors for mammographic mass characterization

Compares the performance of different texture descriptors in distinguishing benign from malignant mammographic lesions. The best discriminators are the models fit from the Laws, Haralick, and 3D geometric surface temperature descriptors, in that order. Fractal dimension was not a good texture descriptor.

System Considerations for Satellite Transmission of Digitized Mammograms

The various system constraints for the successful satellite transmission and display of digitized mammograms are considered. These include the determination of the optimal data compression ratio for enhanced speed of transmission without degradation of image quality as well as interface requirements such as image display format, zoom, and window/level capabilities.

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.