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

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.

Review of the Variations of the Superficial Veins of the Neck

The venous drainage of the neck can be characterized into superficial or deep. Superficial drainage refers to the venous drainage of the subcutaneous tissues, which are drained by the anterior and external jugular veins (EJVs). The brain, face, and neck structures are mainly drained by the internal jugular vein (IJV). The superficial veins are found deep to the platysma muscle while the deep veins are found encased in the carotid sheath. The junction of the retromandibular vein and the posterior auricular vein usually form the EJV, which continues along to drain into the subclavian vein. The anterior jugular vein is usually formed by the submandibular veins, travels downward anterior to the sternocleidomastoid muscle (SCM), and drains either into the EJV or the subclavian vein. Other superficial veins of the neck to consider are the superior, middle, and inferior thyroid veins. The superior thyroid and middle thyroid veins drain into the IJV whereas the inferior thyroid vein usually drains into the brachiocephalic veins.