Significance of 18F-sodium Fluoride Positron Emission Tomography in Characterization of POEMS Osteosclerotic Lesions Better Than 18F-fluorodeoxyglucose Positron Emission Tomography.

Crow-Fukase syndrome (POEMS syndrome) is a rare systemic paraneoplastic syndrome. Bone lesions are manifested by sclerotic osteoblastic lesions often associated with bone pain. Characterization of osseous lesions is always crucial for clinical correlation and better patient management. We present a case where 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT) was unable to characterize a clinically symptomatic patient, and 18F-fluoride PET/CT showed excellent characterization of osteosclerotic lesions. The results were in correlation with already published data and showed that 18F-fluoride PET/CT has better uptake in osteoblastic lesions in POEMS syndrome when compared to 18F-FDG PET/CT and have superior imaging quality in assessing the bone lesions.

Interesting Case

A 42-year-old-female presented in outpatient department with elevated M proteins and was suspected for POEMS syndrome. The patient presented with severe pain in mid and lower back. The patient underwent 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT) for staging and characterization of disease, but no metabolically active focus could be seen in the scan. It was decided in tumor board that osteosclerotic lesions may be imaged using 18F-Floride PET/CT as 18F-fluoride has high sensitivity in characterization of osteosclerotic lesions.[123]

18F-FDG PET/CT was performed according to the institutional protocols. The PET images showed no significant uptake in any part of the body [Figure 1a]; however, CT images showed areas of dense sclerosis involving D-9 and L-5 and upper part of the left femur [Figure 1b–d]. Keeping in view the already published literature, it was assumed that as 18F-FDG PET/CT has less sensitivity for osteosclerotic lesions as compared to lytic lesions.

Figure 1

18F-fluorodeoxyglucose positron emission tomography shows multiple nonfluorodeoxyglucose avid sclerotic lesions involving D-9, L-5 and proximal part of the left femur (a = whole-body fluorodeoxyglucose positron emission tomography scan, b = sagittal slices to show L-5 lesion, c = short-axis slices for D-9 lesion, d = short-axis slices for femoral lesion)

18F-sodium fluoride (18F-NaF) PET/CT in Figure 2a whole-body 18F-NaF scan shows significant tracer uptake in D-9 and L-5vertebral bodies, which could be further appreciable in Figure 2b–d axial slices, showing intense tracer localization in vertebral body of D-9 and L-5. The tracer localization is also appreciable in 18F-NaF (PET alone) images showing its superior sensitivity in terms of characterization of bone lesions when compared to 18F-FDG PET/CT scan.

Figure 2

Multiple osteoblastic sclerotic lesions at the dorsolumbar spine showing good sodium fluoride uptake (arrows) where fluorodeoxyglucose positron emission tomography showed no metabolic activity (a = whole-body positron emission tomography sodium fluoride scan, b = sagittal slices to show L-5 lesion, c = short-axis slices for D-9 lesion, d = short-axis slices for femoral lesion

Results show that sodium fluoride (18F-NaF PET/CT) imaging has high sensitivity in characterization of skeletal osteosclerotic lesions. This may be due to high first-pass clearance of 18F-NaF tracer into bones which combined with modern TOF PET cameras shows excellent lesion characterization in osteosclerotic bone lesions. In our case, we infer that 18F-NaF PET/CT is superior in characterization of sclerotic bone lesions due to its unique pharmacokinetics and may be of help in patients presenting with acute or chronic bone pains in which 18F-FDG PET CT is negative or equivocal in characterizing the nature of osseous lesions.[456]

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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given her consent for her images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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