방사선의학 웹진

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Abstract

PURPOSE:

Increased Ga uptake in the mediastinal/hilar lymph nodes ("lambda") and in the lacrimal/parotid/submandibular glands ("panda") often coexists in patients with sarcoidosis (Sarc-Pts). However, we observed that increased lacrimal/salivary uptake is uncommon on F-FDG PET/CT (FDG-panda) in many Sarc-Pts who showed increased mediastinal/hilar uptake (FDG-lambda). We evaluated parotid and lacrimal FDG activity in Sarc-Pts who showed FDG-lambda in comparison with a control patient group and attempted to find underlying mechanisms to explain the discrepancy between FDG and Ga uptake in these organs.

METHODS:

Parotid FDG activity (FDG-P) was assessed visually using a 0- to 3-point scale (0 being = or minimally > background, and 3 > liver) and quantitatively using SUVmean in 52 confirmed Sarc-Pts with FDG-lambda (lambda group) as well as in 52 non-Sarc-Pts (control group). Lacrimal FDG activity (FDG-L) was assessed visually (0 being = or minimally > subcutaneous tissue, and 1 clearly > subcutaneous tissue).

RESULTS:

There was no significant difference in the parotid SUVmean between lambda (1.88 ± 0.65) and control (1.76 ± 0.62) groups (P = 0.333). Also, there was no difference in visually graded FDG-P between the 2 groups (P = 0.257). None of the patients in all groups showed apparently abnormal (grade 1) FDG-L.

CONCLUSIONS:

Increased FDG-L/FDG-P is rare in Sarc-Pts demonstrating FDG-lambda, which is strikingly different from the clinical experience as well as the reported data on Ga scintigraphy. Discrepancy in various cytokine levels between lacrimal samples and intrathoracic lesions in Sarc-Pts reported in the literature appears to correlate well with variable Ga and FDG uptake in the lacrimal gland and intrathoracic lesions. 

Author information

Shim H1, Joo J, Choi HJ, Hyun H, Gerbaudo VH, Kim CK.

1From the *Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Brigham and Women's Hospital; and †Harvard Medical School, Boston, MA.