Blinded review of retrospectively visible unreported breast cancers: an eye-position analysis.

PURPOSE: To determine whether unreported retrospectively identified cancers on mammograms receive prolonged visual attention and can be reliably detected in a blinded review. MATERIALS AND METHODS: Four experienced mammographers performed a blinded review of a test set of 20 retrospective cases where the cancer was not detected until the next mammographic evaluation, 10 prospective cases where the cancer was initially detected, and 10 cancer-free cases. Two views were digitized and displayed on a workstation. The experiment consisted of an initial impression, during which eye position was monitored, and a final impression, during which viewers zoomed on regions of interest and localized suspicious lesions. Eye-position data were analyzed to determine whether retrospectively visible cancers attracted attention to the same degree as prospectively visible cancers. The initial impression used 1,000 msec as the eye-fixation dwell criterion for detecting a lesion. RESULTS: Initially, 70% of retrospective cancers and 50% of prospective cancers did not attract prolonged visual attention. In prospective cases, detailed examination significantly improved the mean receiver operating characteristic area, from.73 to.88 (P <.01), but in retrospective cases, the mean receiver operating characteristic area barely increased, from.60 to.68, due to a high true-positive-to-false-positive ratio. CONCLUSION: At blinded review, detection of retrospectively visible cancers was significantly inferior to that of prospective cancers. It cannot be assumed that retrospectively identified cancers are intrinsically detectable, because they do not draw prolonged visual attention during visual search for breast cancers.

Sonographic discrimination between benign and malignant breast lesions with use of disparity processing.

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate whether a digital processing technique called disparity processing (DP) can improve the differentiation between benign and malignant breast masses at ultrasound (US) and, thus, reduce the number of benign lesions being sampled for biopsy. MATERIALS AND METHODS: During an US examination, a sonographer slightly varies the pressure of the probe on the breast surface. DP can be used to evaluate pairs of B scans that represent the different parts of this compression cycle. The apparent displacement of the tissue is measured with DP, and a new image, called a correlation map, is constructed. This new image illustrates the similarity between the speckle patterns around each point. The authors evaluated 25 solid lesions with DP. Results were compared with those from (a) histologic examination of specimens obtained with core or surgical biopsy or (b) cytologic examination of specimens obtained with fine-needle aspiration. RESULTS: All 25 lesions were correctly diagnosed with DP. There were no false-positive or false-negative findings. All malignancies demonstrated a relatively low-brightness halo around the lesion perimeter with evidence of discontinuity. All benign lesions were associated with relatively high-brightness, continuous halos. CONCLUSION: The results suggest that DP can help differentiate benign from malignant masses.

Paper chromatography prior to cortisol RIA allows for accurate use of the dexamethasone suppression test in chronic renal failure.

The assessment of the hypothalamic-pituitary-adrenal axis in patients with chronic renal failure (CRF) on hemodialysis is often hampered by abnormal responses to the standard 1-mg dexamethasone suppression test. Various mechanisms have been proposed to explain this lack of suppressibility. The present study was designed to look into the mechanisms possible for these findings in patients with CRF. We studied 6 patients with CRF on hemodialysis and 5 healthy subjects utilizing the 1-mg dexamethasone suppression test as well as the 50-mg hydrocortisone suppression test. Samples were assayed for dexamethasone, adrenocorticotropic hormone, corticosterone, and cortisol by both direct radioimmunoassay (RIA) and RIA after paper chromatography. Utilizing the direct cortisol RIA, 4 of 6 patients with CRF exhibited blunted dexamethasone suppression, while all 6 patients showed normal suppressibility after dexamethasone when cortisol was measured after paper chromatography. In contrast, all controls showed normal suppressibility regardless of the cortisol assay procedure used. The hydrocortisone suppression test was unreliable in the setting of CRF. Mean dexamethasone levels were similar in both groups. Plasma adrenocorticotropic hormone levels were significantly higher in the CRF patients, possibly indicative of an underlying hypothalamic-pituitary-adrenal axis abnormality. Abnormalities in dexamethasone suppression testing in patients with CRF may be explained by the overestimation of cortisol levels by direct RIA rather than by alteration of dexamethasone absorption or metabolism. Measurement of cortisol after paper chromatography is superior to direct RIA of cortisol in patients with CRF.