Unsupervised segmentation of the prostate using MR images based on level set with a shape prior.

Prostate cancer is the second leading cause of cancer death in American men. Current prostate MRI can benefit from automated tumor localization to help guide biopsy, radiotherapy and surgical planning. An important step of automated prostate cancer localization is the segmentation of the prostate. In this paper, we propose a fully automatic method for the segmentation of the prostate. We firstly apply a deformable ellipse model to find an ellipse that best fits the prostate shape. Then, this ellipse is used to initiate the level set and constrain the level set evolution with a shape penalty term. Finally, certain post processing methods are applied to refine the prostate boundaries. We apply the proposed method to real diffusion-weighted (DWI) MRI images data to test the performance. Our results show that accurate segmentation can be obtained with the proposed method compared to human readers.

Evaluation of enterolithiasis in equids: 900 cases (1973-1996).

OBJECTIVE: To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and other equids with enterolithiasis. DESIGN: Retrospective study. ANIMALS: 900 equids with enterolithiasis. PROCEDURE: Medical records from equids with enterolithiasis admitted between 1973 and 1996 were reviewed. Data on signalment, history, physical examination and clinicopathologic findings, surgical findings, and outcome were compiled from records and from telephone interviews with owners. Sex and breed predilections were determined by comparison of the study population with the general hospital population of equids during the same time period. RESULTS: Equids with enterolithiasis represented 15.1% of patients admitted for treatment colic, and 27.5% of patients undergoing celiotomy for treatment of colic. Arabian and Arabian crosses, Morgans, American Saddlebreds, and donkeys were significantly overrepresented, and Thoroughbreds, Standardbreds, warmbloods, and stallions were significantly underrepresented in the study population, compared with the hospital population. The mean age of equids with enterolithiasis was 11.4 years. The most common historic findings were signs of intermittent colic (33.3%) and passage of enteroliths in the feces (13.5%). Physical examination findings were similar to those found in equids with other forms of nonstrangulating large colon obstructive disease. Fifteen percent (131) developed gastrointestinal tract rupture caused by an enterolith that necessitated euthanasia. Short-term and 1-year survival rates for equids undergoing celiotomy for treatment of enterolithiasis and recovering from anesthesia were excellent (96.2 and 92.5%, respectively), and postoperative complications were uncommon. Recurrence of enterolithiasis was identified in 7.7% of the study population. CLINICAL IMPLICATIONS: Results indicated that shortterm and 1-year survival rates for equids undergoing surgery for enterolithiasis are excellent. Identification of signalment, history, and management factors may help identify equids with a high risk for development of enterolithiasis.

Abdominal radiography for diagnosis of enterolithiasis in horses: 141 cases (1990-1992).

Medical records of 245 horses that had been evaluated by use of abdominal radiography between January 1990 and December 1992 were reviewed. One hundred forty-one horses subsequently had a postmortem examination or surgical exploration performed for definitive lesion diagnosis. The signalment, diagnosis, site, and number of enteroliths were obtained from the medical records. Radiographs were evaluated individually by 3 reviewers for the presence of enteroliths, preferred diagnostic view, evidence of large colon tympany, and film quality. Of the 141 cases reviewed, 66.7% (94/141) had confirmed enterolithiasis. Enteroliths were identified in the right dorsal colon of 59 horses, in the transverse colon of 28, in the small colon of 24, and in the ventral colon of 1 (enteroliths were detected in multiple sites in 12 horses). For the 3 reviewers, mean sensitivity was 76.9% and specificity was 94.4%. Mean positive-predictive value was 96.4%, and negative-predictive value was 67.5%. Cases involving only large colon enteroliths were correctly diagnosed 83.2% of the time, compared with 41.6% of the time for cases involving small colon enteroliths. Enteroliths were evident in 54.8% of the horses with radiographic signs of large colon distention. Fifteen horses had enteroliths in the small colon, 4 in the transverse colon, and 4 in the dorsal colon. Radiographic quality was evaluated and scored as adequate (0), underexposed (-1), overexposed (1), or incomplete. Mean score was -0.5, and there were 21 (14.9%) incomplete studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal dysplasia and benign ureteropelvic polyps associated with hydronephrosis in a foal.

A 4-month-old male Trakehner foal with a history of hematuria, poor growth, and abnormal hair was found to have unilateral hydronephrosis and hydroureter, as determined by ultrasonography and surgical exploration. Nephrectomy and ureterectomy were performed as treatment. Gross examination of the ureter and kidney revealed renal pelvic and ureteral polyps causing obstruction and subsequent hydronephrosis. The histologic features were consistent with renal dysplasia. The polyps and renal dysplasia were likely to be congenital, but the etiopathogenesis is not known. The finding that urinary outflow obstruction can disrupt nephrogenesis and lead to renal dysplasia supports the view that the polyps developed, blocked urine flow, and caused the hydronephrosis and renal dysplasia in the foal.