Assessment of successful incorporation of cages after cervical or lumbar intercorporal fusion with [(18)F]fluoride positron-emission tomography/computed tomography

The purpose of this study is to assess the successful incorporation of cages in patients after cervical or lumbar intercorporal fusion with positron-emission tomography/computed tomography (PET/CT). Twenty patients (14 female and 6 male; mean age 58 years, age range 38–73 years) with 30 cervical (n = 13) or lumbar (n = 17) intercorporal fusions were prospectively enrolled in this study. Time interval between last intercorporal intervention and PET/CT ranged from 2 to 116 months (mean 63; median 77 months). IRB approval was obtained for all patients, and written informed consent was obtained from all patients. About 30 min prior to PET/CT scanning, 97–217 MBq (mean 161 MBq) 18F-fluoride were administered intravenously. Patients were imaged in supine position on a combined PET/CT system (Discovery RX/STE, 16/64 slice CT, GE Healthcare). 3D-PET emission data were acquired for 1.5 and 2 min/bed position, respectively, and reconstructed by a fully 3D iterative algorithm (VUE Point HD) using low-dose CT data for attenuation correction. A dedicated diagnostic thin-slice CT was optionally acquired covering the fused region. Areas of increased 18F-fluoride uptake around cages were determined by one double-board certified radiologist/nuclear physician and one board certified radiologist in consensus. In 12/20 (60%) patients, increased 18F-fluoride uptake around cages was observed. Of the 30 intercorporal fusions, 15 (50%) showed increased 18F-fluoride uptake. Median time between intervention and PET/CT examination in cages with increased uptake was 37 months (2–116 months), median time between intervention and PET/CT examination in those cages without increased uptake was 91 months (19–112 months), p (Wilcoxon) = 0.01 (one-sided). 14/29 (48%) cages with a time interval > 1 year between intervention and PET/CT scan showed an increased uptake. In conclusion, PET/CT frequently shows increased 18F-fluoride uptake in cervical and lumbar cages older than 1 year (up to almost 8 years in cervical cages and 10 years in lumbar cages) possibly indicating unsuccessful fusion due to increased stress/microinstability

B¯okin-b¯obai

Bone scintigraphy has a long and useful track record in the early detection of trauma, both acute and chronic, since its introduction in the 1970s as a new imaging modality. It has been widely used in the early detection of occult bone injury that is not evident on plain x-ray, with a significant increase in sensitivity with the adoption of SPECT. Adoption of scintigraphy into the investigation of sporting injuries was a more successful enterprise in the last 1970s and 1980s and, in many instances of stress fracture and the medial tibial stress syndrome, became the reference standard. MRI has diminished the role of scintigraphy with its exquisite contrast resolution and excellent spatial resolution, especially for soft-tissue injury. It reflects the cyclical nature of technological advances in imaging. We are now at another exciting crossroad, where SPECT has been combined with CT, allowing the marriage of the superb contrast resolution of SPECT with the high spatial resolution of CT. Early experience suggests that there is an incremental value of 25-30 % over SPECT or CT alone, opening up exciting possibilities for imaging trauma. Evidence for its utility in sporting and non-sporting trauma will be evaluated