We aim to evaluate 18F-NaF uptake by facet joints with hybrid PET-CT technique. Specifically,
we evaluate NaF uptake in the facet joints of the lower lumbar spine, and correlate
with the morphologic grade of facet arthropathy on CT. 30 consecutive patients who
underwent standard vertex to toes NaF PET-CT for re-staging of primary neoplastic
disease without measurable or documented bony metastases were identified. Maximum
(SUVmax) and average (SUVavg) standardized uptake values were calculated for each
L3-4, L4-5, and L5-S1 facet joint (n = 180) and normalized to average uptake in the
non-diseased femur. A Pathria grade (0-3) was assigned to each facet based upon the
CT morphology. Spearman′s rank correlation was performed for normalized SUVmax and
SUVavg with Pathria grade. ANOVA was performed with Tukey-Kramer pairwise tests to
evaluate differences in uptake between Pathria groups. Facet normalized SUVmax (r
= 0.31, P < 0.001) and SUVavg (r = 0.28, P < 0.001) demonstrated a mild positive correlation
with CT Pathria grade. There was a wide range of uptake values within each Pathria
grade subgroup with statistically significant differences in uptake only between Pathria
grade 3 as compared to grades 0, 1, and 2. In conclusion, NaF uptake and morphologic
changes of the facet joint on CT are weakly correlated. Physiologic information provided
by NaF uptake is often discrepant with structural findings on CT suggesting NaF PET
may supplement conventional structural imaging for identification of pain generating
facet joints. Prospective investigation into the relationship of facet joint NaF uptake
with pain and response to pain interventions is warranted.
Keywords
Lumbar facet - sodium fluoride positron emission tomography - positron emission tomography-computed
tomography - 18F-sodium fluoride
