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18F-Naf Pet Evaluation Of Facet Joints Of The Lower Lumbar Spine Compared With Ct Graded Arthropathy 2013

Category General Spine Jason F. Talbott, MD, PhD
Spencer Behr, MD
Ronnie Sebro, MD, PhD
Miguel H. Pampaloni, MD, PhD
Sharmila Majumdar, PhD
William P. Dillon, MD
Purpose Lumbar facet syndrome is a major cause of morbidity in the United States1.   Commonly employed radiographic studies, including CT, show poor correlation with outcomes following diagnostic facet blocks2-3.  Noninvasive imaging techniques that more accurately identify patients who will benefit from interventional therapies for facet syndrome are needed.   As a measure of bone turnover and blood flow, 18F-NaF (NaF) PET may identify functional changes in the facet joint not reflected by simple structural abnormalities seen on CT4.   Correlation between NaF uptake and CT grade of facet arthropathy was tested. Materials & Methods 60 patients who underwent NaF PET-CT imaging over a 3 year period for cancer restaging were retrospectively identified.  No patient had documented metastatic disease.  Whole body PET-CT images were acquired approximately 45 minutes following IV administration of 160 MBq 18F-NaF.  Maximum (SUVmax) and mean (SUVavg) NaF uptake within the bilateral L3-L4, L4-L5, and L5-S1 facet joints was measured using a volumetric region of interest (ROI) encompassing the entire facet joint and standardized relative to uptake within the normal femoral diaphysis.  Facet arthropathy was graded on CT images using Pathria classification.  SUVmax and SUVavg were compared with CT scores of facet arthropathy using nonparametric statistical tools (Spearman rank correlation coefficient). Results CT evidence for facet arthropathy was present in 71% of interrogated joints, with 17% of joints graded as moderate or severe by Pathria criteria.  The average SUVavg within a facet joint was 2.9 (range 1.5 - 7.3, SDEV = 1.4) while the average facet SUVmax was 8.7 (range 4.8 - 28.5, SDEV = 4.4).  There was no significant correlation between SUVavg and CT grade of arthropathy (ρ = 0.06).  Only weak correlation between SUVmax and CT grading (ρ = 0.4) was observed. Conclusion The weak correlation suggested by this preliminary data suggests that NaF PET and CT findings might reflect different ongoing abnormalities in the setting of chronic ongoing facet arthropathy. Further prospective studies utilizing NaF-PET in low back pain patients are warranted to clarify the interpretation of these findings given the potential role of NaF-PET in functional bone imaging. References 1. Cohen S and Raja S: Pathogenesis, Diagnosis, and Treatment of Lumbar Zygapophysial (Facet) Joint Pain.  Anesthesiology 2007; 106;591-614. 2. Revel ME, Listrat VM, Chevalier XJ, Dougados M, Nguyen MP, Vallee C., Wybier M, Gires F, Amor B: Facet joint block for low ack pain:  Identifying predictors of a good response.  Arch Phys Med Rehabil 1992; 73;824-8. 3.  Jackson RP, Jacobs RR, Monesano PX: Facet joint injection in low-back pain: A prospective statistical study. Spine 1988; 13:966-71. 4.  Grant FD, Fahey FH, Packard AB, Davis RT, Alavi A, Treves ST: Skeletal PET with 18F-Flouride: Applying New Technology to an Old Tracer. The J of Nuc Med 2008; 49:68-78.