Indian Journal of Nuclear Medicine

  • Year: 2006
  • Volume: 21
  • Issue: 4

The role of preoperative 18F-FDG-PET/CT imaging and sentinel node scintigraphy and biopsy in the detection of metastases in malignant melanoma.

  • Author:
  • Baljinder Singh1, H Palmedo2, M Reinhardt2, U Jaeger2, HJ Biersack2, H Ahmadzadehfar2, T Tütting3
  • Total Page Count: 2
  • DOI:
  • Page Number: 81 to 82

1Department of Nuclear Medicine, PGIMER, Chandigarh, India

2Departments of Nuclear Medicine, Klinik und Poliklinik, Sigmund Freud Str 25, 53105, Bonn, Germany.

3Dermatology, Klinik und Poliklinik, Sigmund Freud Str 25, 53105, Bonn, Germany.

Abstract

In the present study, we evaluated the role of preoperative 18F-FDG-PET/CT scanning, preoperative lymphoscintigraphy (LS), intraoperative lymphatic mapping (LM), and sentinel lymph node biopsy (SLNB) in 45 patients (31M: 14F; mean age 55.0± 16.0 years; median age 60.0 years; range 17–76 years) with malignant melanoma. All these patients had histologically proven primary malignant melanoma (stage IIAV, mean Breslow depth = 3.46 ± 2.57mm; range 1.0mm–12.0 mm, Clarks level III-V) and had no clinical or radiological evidence of regional lymph node metastatic disease. Additionally, PET imaging was performed in 9 patients postoperatively. Preoperative LS detected a total of 94 SLNs (average 2.08 SLN per patient) and demonstrated a single drawing nodal basin in 14 (14/45=31%) patients and multiple (2–5 drawing basins) in the remaining 31 (31/45=69%) patients. Histopathological analysis (HP) demonstrated that only 19 out of the 94 SLNs (19/94=20%) detected by LS were positive for malignancy. These 19 HP positive SLNs were detected in 13 patients. The preoperative LS showed 24 SLNs in these patients. In 3 of these 13 patients, the combined LS/LM/SLNB could pick up 3 additional SLNs, which were not demonstrated by LS alone. The LS alone therefore had a specificity of 84%. However, the specificity was 100% when all the three procedures i.e. LS, LM and SLNB were combined. On the other hand, 18F-FDG-PET imaging demonstrated a very low sensitivity (8%) and PPV (17%) for localizing the sub clinical nodal micrometastases. However, its specificity, NPV and DA was 85%, 72% & 65% respectively. However, on excluding 2 patients with suspicious PET findings but negative follow-up for 1 year, specificity improved to 20%. The important finding was that preoperative PET imaging could accurately exclude regional lymph node metastatic disease in 62% (28/45=62% true negative cases) of the patients. Postoperative PET imaging carried out additionally in 9 patients excluded LN metastases in 7 patients. In the remaining 2 patients, PET findings were true positive for 1 patient and false positive for the 2nd patient. This PET positive lymph node, however, appeared as a non hot LN on Pre PET lymphatic mapping. Therefore, postoperative PET imaging could change the management in at least 1 patient by localizing a hot SLN concentrating FDG, which was positive on subsequent HP examination. It is thus concluded that preoperative PET imaging is not able to detect sub clinical regional lymph nodal micrometastases and therefore, can not substitute LM/SLNB. However, in view of the reasonably high specificity and NPV of this modality, PET imaging definitely has a corroborating role in excluding the regional lymph node metastases by LM & SLNB. Further, the postoperative whole body 18F-FDG-PET imaging has an additional role in demonstrating the local recurrence or distant metastases outside the regional lymph node basins or in evaluating the response to adjuvant interferon therapy.