Background: Second-look ultrasonography (US) is commonly performed for breast lesions detected using magnetic resonance imaging (MRI), but the identification rate of these lesions remains low. We investigated if US methods using anatomical breast structures can improve the lesion identification rate of MR-detected lesions and evaluated the diagnostic performance of fine-needle aspiration cytology (FNAC) of the second-look US using the above-mentioned method.
Methods: We retrospectively assessed 235 breast lesions (hereinafter, "targets") subjected to second-look US following MRI between January 2013 and September 2015. US was employed using the conventional methods, and this assessment measured the positional relationships of lesions with regard to surrounding anatomical breast structures (glandular pattern, Cooper's ligaments, adipose morphology, and vascular routes). Associations were assessed among the following variables: the MRI findings, target size, identification rate, and main US indicators that led to identifying the target; FNAC results and MRI findings; MRI findings and histopathological findings; and FNAC results and histopathological findings. Moreover, the sensitivity and specificity of FNAC were determined.
Results: The identification rate was 99%. The main US indicators leading to identification were a glandular pattern (28-30% of lesions) and other breast structures (~ 25% of lesions). FNAC was performed for 232 targets with the following results: sensitivity of 85.7%, specificity of 91.6%, PPV of 94.1%, NPV of 92.9%, false-negative rate of 14.3%, false-positive rate of 2.1%, and accuracy of 89.7%.
Conclusions: Second-look US using anatomical breast structures as indicators and US-guided FNAC are useful for refining the diagnosis of suspicious breast lesions detected using MRI.
Keywords: Anatomical landmark; Fine-needle aspiration cytology; MRI; Ultrasound.