Value of SPECT/CT for Sentinel Lymph Node Localization in the Parotid and External Jugular Chain

Abstract

Objective: Preoperative single-photon emission computed tomography/computed tomography (SPECT/CT) imaging may aid in the localization of sentinel lymph nodes (SLNs) in cutaneous head and neck malignancy and has been rigorously evaluated for deep cervical lymph nodes. The purpose of this study was to assess the sensitivity, specificity, and positive predictive value (PPV) of SPECT/CT for preoperative localization of nodal basins superficial to the sternocleidomastoid muscle, with comparison to deep nodal basins of the neck. Study Design: Retrospective review. Setting: Tertiary care center. Subjects and Methods: SPECT/CT images obtained preoperatively for patients undergoing SLN biopsy for cutaneous head and neck malignancy between June 2015 and June 2016 were reviewed by a blinded nuclear medicine physician and head and neck surgeon. SPECT/CT imaging was compared to intraoperatively determined SLN location via gamma probe. Sensitivity, specificity, and positive and negative predictive values were determined and compared for superficial (external jugular [EJ] and parotid) nodes vs level II nodes. Results: Fifty-three patients were included in the study. Most had cutaneous melanoma (69.8%). The PPV of EJ/parotid node identification by SPECT/CT imaging was 85.7%, specificity was 88.9%, and sensitivity was 69.2%. Comparatively, the PPV for level II nodes was 76.9%, specificity was 50%, and sensitivity was 85.7%. No significant difference in SPECT/CT predictive value was identified between EJ/parotid and level II node identification (P >.05). Conclusion: SPECT/CT imaging has strong specificity and positive predictability for preoperative localization of SLN superficial to the sternocleidomastoid muscle in cutaneous head and neck malignancy. SPECT/CT imaging may be a useful radiographic aid for preoperative SLN mapping in this patient population.