OBJECTIVE: To evaluate the nature and imaging appearance of incidental enhancing breast lesions detected on a routine contrast-enhanced chest CT. MATERIALS AND METHODS: Twenty-three patients with incidental enhancing breast lesions on contrast-enhanced chest CT were retrospectively reviewed. The breast lesions were reviewed by unenhanced and enhanced CT, and evaluated by observing the shapes, margins, enhancement patterns and backgrounds of breast lesions. A histopathologic diagnosis or long-term follow-up served as reference standard. RESULTS: Sixteen (70%) patients had malignant breast lesions and seven (30%) had benign lesions. In 10 patients, the breast lesions were exclusively detected on contrast-enhanced CT. Using unenhanced CT, breast lesions with fibroglandular backgrounds were prone to be obscured (p < 0.001). Incidental primary breast cancer showed an non-significant trend of a higher percentage irregular margin (p = 0.056). All of the four incidental breast lesions with non-mass-like enhancement were proven to be malignant. CONCLUSION: Routine contrast-enhanced chest CT can reveal sufficient details to allow for the detection of unsuspected breast lesions, in which some cases may be proven as malignant. An irregular margin of incidental enhancing breast lesion can be considered a suggestive sign of malignancy.
Aged ; Breast Diseases/radiography ; Breast Neoplasms/*radiography/secondary ; *Contrast Media ; Female ; Humans ; *Incidental Findings ; Iohexol/*analogs & derivatives/diagnostic use ; Middle Aged ; *Radiography, Thoracic ; *Tomography, X-Ray Computed

BACKGROUNDEarly detection with screening mammography can potentially reduce breast cancer mortality rates. To achieve an efficient screening, a peer review system provides a compensatory double-check reviewing, will hopefully to prevent the omission of detectable lesions and reduce unnecessary recall.

METHODSIn 2009, 4643 initial mammographic screenings reported by 74 screening radiologists had negative results with a recall rate of less than 5%. In the same year, 2538 initial positives screened by 18 screening radiologists had a recall rate higher than 15%. Those 7181 randomized screenings were evenly distributed for reassessment by 39 reviewing radiologists. The disagreement of assessments between the reviewers and screening radiologists was recorded. The differential rate was defined as the number of the disagreements divided by the number of audited films reviewed by a screening radiologist. The equality of the differential rates for each screening radiologists with negative and positive assessments was compared by a Chi-square test. The performance of the 39 auditors was measured by the Kendall's tau statistic. P values less than 0.05 were considered statistically significant.

RESULTSThe mean differential rate for screening radiologists of negative assessments was 6.7% (P = 0.588), while 35.0% for positive assessments were significant (P < 0.001). The result indicated that most of the initial negative assessments reported by the screening radiologists were generally accepted by the reviewers but not the positive assessments. With respect to the 39 reviewers, there was no significant evidence for the association of the difference rates between negative and positive assessments. Nine reviewers were found to have their differential rate for negative and positive assessments larger than the average of the population. Eleven reviewers were found to have their differential rates smaller than the average for both. Thirteen reviewers had their differential rates smaller than the average for negative assessments but larger than the average for positive assessments. The opposite condition was found for six reviewers. The Kendall's tau statistic was 0.038 (P = 0.735).

CONCLUSIONSReviewers usually agreed with the opinion of the initial screening doctors who reported negative findings. Therefore, a 5% recall rate as the lower range of reviewing negatives may be still too high. The recall rate of more than 15% was significantly related to improper interpretation, especially when the differential rate is 25% or higher, a warning to the underperforming screening radiologist is recommended. An ideal reviewer should interpret films independently. Reviewers with tendencies to be followers or contrarians should not be enrolled in the reviewing system.

Breast Neoplasms ; diagnostic imaging ; Early Detection of Cancer ; Female ; Humans ; Mammography ; Peer Review ; Reproducibility of Results ; Taiwan