The clinical usefulness of (18)F-FDG PET/CT for the evaluation of lymph node metastasis in periorbital malignancies

Abstract

Objective: The aim of this study was to assess the clinical role of (18)F-FDG PET/CT for the evaluation of lymph node metastasis in periorbital malignancies, compared with CT alone.

Materials and methods: We analyzed eighteen PET/CT and CT scans in 15 patients with biopsy-proven periorbital malignancies. We compared the diagnostic capabilities of PET/CT and CT with regard to nodal metastasis by level-by-level analysis and by N staging prediction. The reference standards were surgical pathology (n = 7) from dissected lymph node specimens and the results from radiological follow-up (n = 11, mean 20.5 months; range 10-52 months). Moreover, any changes in patient care as prompted by PET/CT were recorded and compared with treatment planning for CT alone.

Results: PET/CT had a sensitivity of 100%, while CT had a sensitivity of 57% (p = 0.03) for nodal metastasis by level-by-level analysis. PET/CT had a specificity of 97%, positive predictive value of 93%, negative predictive value of 100%, and diagnostic accuracy of 98%, while the CT values for these same parameters were 97%, 89%, 82%, and 84%, respectively. PET/CT correctly predicted N staging with an accuracy of 100%, while CT was only 83% accurate (p = 0.01). Regarding the impact on patient care, the extent of surgery for regional lymph nodes and the treatment decision were modified by PET/CT in 39% of patients.

Conclusion: PET/CT could provide useful information in the management of regional lymph node metastases in patients with periorbital malignancies.

Fig. 1

65-year-old male patient with sebaceous carcinoma in upper eyelid. A. On contrast-enhanced CT, no definite lesion is detected around parotid gland. B, C. On PET/CT, malignant lesion with high glucose uptake of SUV 4.7 is diagnosed at same site (arrows). According to fused image, malignant lesion is located around parotid gland.

Fig. 2

56-year-old male patient with sebaceous carcinoma in upper eyelid. A. On contrast-enhanced CT, upper jugular lymph node behind angle of mandible is considered benign, with pattern of low enhancement and oval shape (arrow). B, C. On PET/CT, same lesion showed asymmetrical glucose uptake with SUV 2.2 and is diagnosed as metastatic lymph node (arrows). As result, surgical fields were extended to include specific lymph node, which was pathologically proven to have metastatic lesion.