Practical issues of experimental ROC analysis. Selection of controls.

Receiver operating characteristics (ROC) analysis has been used in many medical imaging applications during the past decade. With the recent expansion of the ROC methodology to multi-disease studies, several reports have begun to address both the theoretical and experimental design issues associated with such studies. While the appropriate selection, classification, and verification of actually positive cases is carefully addressed in the literature, similar considerations are rarely given to the selection of actually negative controls for these studies. In this paper, theoretical considerations and experimental data are provided to demonstrate the significance of this very issue.

Metastatic cancer in Paget's disease of bone. A case report.

A 50-year-old white male presented with concurrent Paget's disease of bone and metastatic adenocarcinoma. Our review of the literature and our clinical experience suggests that carcinoma coexisting at the site of bone involved with Paget's disease occurs more commonly than has been recognized. The paucity of reports of tumor metastatic to sites of Paget's disease of bone may be due to an artifact of data collection. The differentiation of metastatic from de novo tumors must be accomplished by biopsy, and the diagnosis is essential for appropriate treatment. Commonly a correlation of known tumor types with Paget's disease is made, and metastatic tumors are excluded.

Acid-base disturbances in cardiogenic pulmonary edema.

Eighty-one consecutive cases of uncomplicated cardiogenic pulmonary edema (CPE) were retrospectively graded for severity of chest roentgenogram (CXR) changes and grouped according to primary acid-base abnormalities, either single or mixed. Mean age was 72, 50 male, 31 female. Twenty-three percent had no acid-base disturbances (ABD). Isolated respiratory alkalosis was most common (41%), followed by metabolic acidosis, 22%; metabolic alkalosis, 10%, and respiratory acidosis, 9%. Age, sex, race distribution, morbidity and mortality were not significantly different between the groups. Overall mortality was 17%. Significantly higher mortality was associated with age over 70, pH less than 7.4, and presence of acute myocardial infarction. CXR scores did not correlate with pH, pCO2 or pO2, mortality or morbidity. Some patients with the most severe ABDs recovered while others, who had no ABD on presentation, eventually died. Thus, in 81 consecutive episodes of uncomplicated CPE, isolated respiratory alkalosis was the commonest ABD, occurring in 41%. No correlation was found between ABD and severity of CPE, morbidity or mortality.

Normal sellar variations in frontal tomograms.

Frontal tomograms of 100 normal sellae were examined. The sellar floor was usually flat or had a smooth central depression of less than 2 mm. Six per cent had a marked central depression. In such cases, the lateral angles of the sellar floor, usually rounded, may be sharp, so that the diagnosis of intrasellar lesions cannot be based on such alterations. Where one or more septa divided the sphenoid sinus asymmetrically, sellar floor configuration was modified in 21% of cases. The normal sellar floor may have a slope of up to 8 degrees, making analysis of subtle contour variations difficult.