Digital chest imaging using a 57-cm image intensifier: a receiver-operating characteristic study of user performance.

Chest radiography provides one of the great challenges to digital diagnostic imaging because of (1) the relatively large size of the chest field, (2) the contrast range required to resolve subtle pathological changes in soft tissue density, and (3) the high degree of spatial resolution required to discriminate pathological detail. The field size problem was resolved by using a 57-cm image intensifier whose video output of the chest could be digitized. The issue of contrast resolution was addressed in a recently completed receiver-operating characteristic study of the detectability of low-contrast densities in a humanoid chest phantom. The latter indicated that, despite the smaller size of the digital image, they were adequate for resolving clinically significant soft-tissue densities. The question of spatial resolution in digital diagnostic images is addressed in the study presented. A set of 41 clinical cases were selected to provide the typical range of diagnostic type experienced in routine diagnostic radiology. The images were each presented as conventional film, digital laser-printer, and digital video images. The results of an ROC analysis of five readers' performance in each of the viewing modes is presented.

Preoperative needle localization to detect early breast cancer.

A retrospective review of 200 consecutive female patients who had undergone mammographically controlled needle localizations was performed to assess the effectiveness of the technique and to analyze the number and characteristics of malignancies found in this group. Fine-needle localization was recommended if one of the following criteria was present: (1) evidence of a mass, (2) microcalcifications, (3) architectural distortion. Of the 200 localizations, 192 specimen radiographs were analyzed: 186 contained the lesion, 6 (3 percent) missed the lesion. Forty-eight cancers were detected (24 percent). The reasons for biopsy were microcalcification, 61 percent; presence of a mass, 25 percent; abnormal architecture, 14 percent. Histologically the cancers included 38 invasive plus 10 in-situ tumors. The predominant histologic cell type was ductal in origin with only four having lobular characteristics. In the definitive treatment of these patients, pathologic findings of the lymph nodes showed 2 of the 38 were positive for metastases. In summary, the technique of preoperative needle localization in this series indicates a 93 percent success rate. An analysis of the surgical intervention indicates that conservative breast surgery is the treatment of choice. Another result is the detection of high-risk malignant lesions such as duct and lobular hyperplasia that require close follow-up.