Factors Affecting Accuracy of Stereotactic Radioisotope-guided Occult Lesion Localisation for Breast Lesions

Abstract

Objectives:To assess the surgical success rate of stereotactic radioisotope-guided occult lesion localisation (ROLL) and to identify factors affecting its accuracy. Methods: We retrospectively identified all stereotactic ROLL procedures from June 2017 to August 2018 at a regional hospital in Hong Kong. Demographic data, imaging results, previous biopsy records, surgical records, and pathology results were reviewed. Independent-sample t tests and Fisher's exact test were used to assess the association of multiple factors (including age, breast thickness, depth of lesion, type of target, approach direction, pathology, operator experience) with localisation accuracy using a 5-mm deviation between the centres of the mammographic targets and the scintigraphic image as the threshold. Results: A total of 77 ROLL procedures were identified. Of them, 55 were localisations of nonpalpable lesions and 22 were combined radioisotope-guided sentinel node and occult breast lesion localisations. The overall surgical success rate for removal of the target lesion was 85.7%, and for excision of malignant nonpalpable breast lesions with clear margins the success rate was 83.9%. Specimen mammogram and scintigraphic images were available in 68 cases for subsequent analysis for factors affecting localisation accuracy. A preoperative diagnosis of invasive carcinoma was associated with poorer target localisation (p = 0.015). Injection of radioisotope via a lateromedial direction was associated with better target localisation (p = 0.044). Conclusion: Stereotactic ROLL is effective in localising nonpalpable breast lesions with a high surgical success rate.There is a significant association between invasive carcinoma with worse localisation. Injection of radioisotope in lateromedial directions is associated with better localisation accuracy.