Two-day lymphoscintigraphic imaging for melanoma.

OBJECTIVES: Sentinel lymph node mapping has a long history of successful use in the staging and management of cutaneous melanoma. Most practitioners inject the primary site with radiocolloid the evening before or on the day of lymphoscintigraphy. We have found that imaging the day after lymphoscintigraphic injection is quite feasible; it decreases background radioactivity and makes scheduling easier. We aimed to determine whether 2-day lymphoscintigraphy is as effective at defining nodes as 1-day lymphoscintigraphy. MATERIALS AND METHODS: We reviewed the records of 172 patients who underwent lymphoscintigraphy over a 6-year period, all of whom had a diagnosis of melanoma and had undergone 2-day lymphoscintigraphy with imaging on both the day of injection and the day immediately after. The number of basins and the basin pattern were then examined when a discrepancy was seen in the reports in order to decide whether an actual discrepancy between images was present. The number of nodes on same-day and next-day imaging was then evaluated as well. RESULTS: On same-day imaging, the number of basins identified was three node basins (NBs) in five patients, two NBs in 42 patients, one NB in 123 patients and no NB in two patients. On next-day imaging, the number of basins identified was three NBs in five patients, two NBs in 36 patients, one NB in 129 patients and no NB in two patients. The difference in the number of basins between same-day and next-day imaging was not significant once cases such as iliac, para-aortic and pelvic nodes, which do not affect surgical planning, were excluded (P=0.08). The pattern of nodes within the basin was also examined, and the presence or disappearance of disappearing nodes correlated with timing of the next-day images. All cases of disappearing nodes occurred at least 19 h after injection, and cases of disappearance of significant nodes occurred at at least 22 h. The absolute number of nodes declined in 45 cases, remained the same in 124 and increased in three. CONCLUSION: Overall, the same number of basins and, usually, nodes can be detected on the day after injection, as long as the time after injection does not significantly exceed 19 h.

Duke Scholars

Author Olga Gennadyevna James Radiology, Nuclear Medicine

Author Salvador Borges-Neto Radiology, Nuclear Medicine