Olga M. B. Gatewood

Segmentation algorithms for detecting microcalcifications in mammograms

The presence of microcalcification clusters in mammograms contributes evidence for the diagnosis of early stages of breast cancer. In many cases, microcalcifications are subtle and their detection can benefit from an automated system serving as a diagnostic aid. The potential contribution of such a system may become more significant as the number of mammograms screened increases to levels that challenge the capacity of radiology clinics. Many techniques for detecting microcalcifications start with a segmentation algorithm that indicates all candidate structures for the subsequent phases. Most algorithms used to segment microcalcifications have aspects that might raise operational difficulties, such as thresholds or windows that must be selected, or parametric models of the data. We present a new segmentation algorithm and compare it to two other algorithms: the multi-tolerance region-growing algorithm, which operates without the aspects mentioned above, and the active contour model, which has not been applied previously to segment microcalcifications. The new algorithm operates without threshold or window selection or parametric data models, and it is more than an order of magnitude faster than the other two.

Streptokinase Salvage of Renal Function After Renal Vein Thrombosis

Excerpt There is little published information on the use of fibrinolytic therapy in renal vein thrombosis. Isolated case reports (1, 2) of patients with renal vein thrombosis so treated have been u...

Computerized tomography in the diagnosis of transitional cell carcinoma of the kidney

Abstract We present 8 patients with transitional cell carcinoma of the kidney who underwent preoperative computerized tomographic examination of the lesions. The computerized tomographic findings are discussed and are correlated with the conventional radiographic appearance. The tumor presents on computerized tomographic examination as a solid mass in the renal pelvis and/or in a ballooned calix, with displacement and compression of the renal sinus fat. It shows attenuation values of 8 to 20H and enhances minimally after intravenous injection of iodinated contrast material. Trapping of contrast material in curvilinear caliceal spaces or in compressed collecting ducts around the periphery of the tumor results in crust-like rims of contrast density tightly and persistently encircling portions of the tumor. Retention of contrast material in obstructed tubules results in accentuated delayed enhancement of the renal parenchyma surrounding the larger lesions. A striated parenchymal pattern, secondary to uneven collecting duct obstruction, also may be seen on delayed views. The reniform contour of the kidney usuallyis preserved even in the presence of larger neoplasms.

Diabetic Fibrous Mastopathy: Case Reports and Radiologic‐Pathologic Correlation

Abstract: Diabetic fibrous mastopathy, an unusual finding in patients with early onset, long‐standing insulin dependent diabetes, can present as a palpable mass with mammographic and sonographic findings highly suggestive of breast cancer. These suspicious clinical and imaging findings necessitate a biopsy, which demonstrates characteristic findings of dense, keloid scarring and intralobular lymphocytic infiltrates. We present 2 cases of diabetic fibrous mastopathy with characteristic mammographic, sonographic, and pathologic findings diagnosed with ultrasound guided core needle biopsy and confirmed with surgical excision. In the appropriate clinical setting, a patient with long‐standing insulin dependent diabetes with a firm, mobile breast mass and characteristic sonographic findings of a hypoechoic mass with lobulation and marked posterior acoustic shadowing should suggest the possibility of diabetic fibrous mastopathy. Awareness of this entity may obviate the need for surgical excision in patients whose clinical, imaging, and pathologic findings are consistent with diabetic fibrous mastopathy.

CT demonstration of colovesical fistulae secondary to diverticulitis

Colovesical fistula, a not infrequent complication of diverticulitis, can be difficult to demonstrate by commonly used diagnostic imaging modalities. We present four cases in which computed tomography was used to detect the presence of such a fistula. Computed tomography readily detected air within the bladder earlier and without equivocation when compared with other imaging techniques. It was useful also in the assessment of the extent and the degree of pericolonic inflammation, thus playing an important role in preoperative surgical planning and postoperative follow-up.

Automated recognition of microcalcification clusters in mammograms

The widespread and increasing use of mammographic screening for early breast cancer detection is placing a significant strain on clinical radiologists. Large numbers of radiographic films have to be visually interpreted in fine detail to determine the subtle hallmarks of cancer that may be present. We developed an algorithm for detecting microcalcification clusters, the most common and useful signs of early, potentially curable breast cancer. We describe this algorithm, which utilizes contour map representations of digitized mammographic films, and discuss its benefits in overcoming difficulties often encountered in algorithmic approaches to radiographic image processing. We present experimental analyses of mammographic films employing this contour-based algorithm and discuss practical issues relevant to its use in an automated film interpretation instrument.

Computed tomography of adult neuroblastoma.

The computed tomographic (CT) findings in five adult patients with neuroblastoma and in one with ganglioneuroblastoma are presented. Four patients had abdominal and thoracic disease, one had abdominal disease only, and one had isolated chest involvement. The CT findings are nonspecific and may be confused with lymphoma. Nevertheless, multifocal presentation, particularly if it includes the posterior mediastinum and association with diffuse or focal bone involvement, when present, should suggest the diagnosis and lead to appropriate laboratory and histopathologic workup.

Computed tomography in calcified renal masses.

Five patients with calcified renal masses were evaluated with angiography and postcontrast computed tomography (CT). Computed tomography showed no contrast enhancement of the mass in four patients, three with avascular hypernephromas and one with a renal cyst; in each case, the lesion was totally avascular on angiography. In the fifth case, the lesion enhanced on CT and proved to be an aneurysm. It is concluded that angiography is most informative in calcifled renal masses that demonstrate contrast enhancement on CT.

Detection of microcalcification clusters using neural networks

One of the earliest mammographic signs of breast cancer, a cluster of microcalcifications, is difficult to detect visually, due to the small size of microcalcifications and their resemblance to other bright structures in mammograms. A fully automated algorithm that we developed for detecting clusters of microcalcifications extracts features that represent individual microstructures using the contour map of the mammogram. This allows computations without using predetermined areas of interest (kernels). The extracted features quantify visual recognition criteria. Microcalcifications are discriminated from other microstructures using multi-layer feedforward neural networks whose inputs are the extracted features.<<ETX>>

CT configuration of the enlarged adrenal gland.

Computed tomography was used to study 31 enlarged adrenal glands in 26 patients. The specific diagnoses were: 12 metastases, 7 pheochromocytomas, 7 adenomas, 2 carcinomas, 2 adrenal hemorrhages, and 1 cyst. Enlarged adrenal glands were frequently found to have an elongated, ovoid cross-sectional appearance. Twenty-four of the 31 adrenal glands (77%) had a length to width ratio of 1.2 or greater. The limited space available for uniform concentric expansion of the enlarging gland appears to be the chief factor causing adrenal masses to assume an ovoid shape. Inasmuch as the upper pole of the unenhanced kidney and the inferior vena cava may both exhibit a similar cross-sectional appearance, cognizance of the potential ovoid configuration of the enlarged adrenal gland should facilitate detection of adrenal masses.