Focal Breast Lesions in Clinical CT Examinations of the Chest: A Retrospective Analysis

Abstract

Purpose Based on radiological reports, the percentage of breast cancers visualized as incidental findings in routine CT examinations is estimated at ≤ 2 %. In view of the rising number of CT examinations and the high prevalence of breast cancer, it was the goal of the present study to verify the frequency and image morphology of false-negative senological CT findings.

Materials and Methods All first contrast-enhanced CT examinations of the chest in adult female patients carried out in 2012 were retrospectively included. A senior radiologist systematically assessed the presence of breast lesions on all CT images using the BI-RADS system. All BI-RADS ≥ 3 notations were evaluated by a second senior radiologist. A consensus was obtained in case of differing BI-RADS assessments. Reference diagnoses were elaborated based on all available clinical, radiological and pathological data. The findings of the CT reports were classified according to the BI-RADS system and were compared with the retrospective consensus findings as well as with the reference diagnoses.

Results The range of indications comprised a broad spectrum including staging and follow-up examinations of solid tumors/lymphoma (N = 701, 59.9 %) and vascular (190, 16.2 %), inflammatory (48, 4.1 %) and pulmonologic (22, 1.9 %) issues. BI-RADS 1/2 classifications were present in 92.5 % and BI-RADS 6 classifications were assessed in 1.7 % of the 1170 included examinations. 68 patients (5.8 %) had at least one lesion retrospectively classified as BI-RADS 3 – 5. The histological potential was known in 57 of these lesions as benign (46, 3.9 %) or malignant (11, 0.9 %). 13 BI-RADS 4/5 consensus assessments (1.1 %) were false-positive. 2 of the 10 lesions classified as being malignant based on the further clinical and radiological course were not mentioned in the written CT reports (0.2 %). Both false-negative CT reports were therapeutically and prognostically irrelevant.

Conclusion The relative frequency of BI-RADS 3 – 5 findings was 5.8 %. It reflects the situation encountered in clinical imaging for primarily non-senologic questions and therefore differs from what would be expected in a dedicated screening program. The rates of known false-positive BI-RADS 4/5 findings in the retrospective evaluations (1.1 %) and of false-negative findings in the written CT reports (0.2 %) reflect the different diagnostic approaches of image-based senological screening and radiological examinations indicated in order to solve clinical problems not primarily concerning the breast region. Statements regarding the prevalence of clinically occult breast cancers can only be made with caution in the presented, highly selective group of patients due to the often incomplete visualization of breast tissue and the retrospective approach.

Key points 

• Intramammary mass and non-mass lesions needing clarification may be present in up to 5.8 % of all contrast enhanced CT-examinations of the female chest.

• Irregular forms, unscharp/spiculated margins, inhomogeneous matrices and a pronounced contrast medium enhancement point towards a malignant genesis of an intramammary mass or non-mass lesion.

• The results of the study highlight the importance of paying systematical and targeted attention on senological additional findings in CT-examinations of the chest also in other clinical settings than that of the included patients in a clinic with oncological main focus.

Zitierweise

• Krug KB, Houbois C, Grinstein O et al. Focal Breast Lesions in Clinical CT Examinations of the Chest: A Retrospective Analysis. Fortschr Röntgenstr 2017; 189: 977 – 988

Key words

breast - CT - breast cancer - metastases

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