Fig. 4.

Composite image compilation from the lymphoscintigraphy, SPECT/CT, post-excision PGC image, and SLN micrograph of the four patients in whom the PGC detected additional melanoma-positive SLNs. Case 1: planar lymphoscintigraphy (1a) and SPECT/CT (1b) visualized two SLNs in the right inguinal and pelvic basins. After conventional surgery, the PGC identified two additional SLNs in the suprainguinal basin and two in the distal external iliac basin. All these SLNs were negative except for one distal external iliac SLN (indicated by an arrow in 1c and micrograph of 1d). The removal of this SLN prevented a false-negative procedure. The other SLN in 1c (not marked by an arrow) was a suprainguinal one, which was negative. Case 2: planar lymphoscintigraphy (2a) and SPECT/CT (2b) visualized one left femoral  SLN. After conventional surgery, the PGC identified one additional femoral SLN (2c), which was removed and upstaged the patient from one to two melanoma-positive lymph nodes (2d). Case 3: Planar lymphoscintigraphy (3a) and SPECT/CT (3b) visualized two SLNs in the right  axilla. After conventional surgery, the PGC identified one additional SLN (3c) in the axilla. This SLN was removed, being the only melanoma-positive lymph node (3d) preventing a false-negative procedure. Case 4: planar lymphoscintigraphy (4a) and SPECT/CT (4b) visualized one right femoral SLN. After conventional surgery, the PGC identified one additional femoral SLN (4c), which was removed and upstaged the patient from one to two melanoma-positive lymph nodes (4d). Thus, PGC upstaged four patients from one to two positive lymph nodes in two patients and from negative to positive SLN status in the remaining two patients. SPECT single photon emission computed tomography, CT computed tomography, PGC portable gamma camera, SLN sentinel lymph node