RT Journal Article SR Electronic T1 18F-FDG PET Detects Inflammatory Infiltrates in Spinal Cord Experimental Autoimmune Encephalomyelitis Lesions JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1269 OP 1276 DO 10.2967/jnumed.111.102608 VO 53 IS 8 A1 Dorothea Buck A1 Annette Förschler A1 Constantin Lapa A1 Tibor Schuster A1 Patrick Vollmar A1 Thomas Korn A1 Stefan Nessler A1 Christine Stadelmann A1 Alexander Drzezga A1 Andreas K. Buck A1 Hans-Jürgen Wester A1 Claus Zimmer A1 Bernd-Joachim Krause A1 Bernhard Hemmer YR 2012 UL http://jnm.snmjournals.org/content/53/8/1269.abstract AB Multiple sclerosis (MS) is a heterogeneous disease with respect to lesion pathology, course of disease, and treatment response. Imaging modalities are needed that allow better definition of MS lesions in vivo. The aim of this study was to establish an MRI- and PET/CT-based imaging modality and to evaluate approved and promising PET tracers in experimental autoimmune encephalomyelitis (EAE), the animal model of MS. Methods: MRI and PET/CT scans were obtained in Dark agouti rats with EAE and healthy control rats. The PET tracers 2-18F-fluoro-2-deoxy-d-glucose (18F-FDG), 3′-deoxy-3′-18F-fluorothymidine (18F-FLT), and O-(2-18F-fluoro-ethyl)-l-tyrosine (18F-FET) were used as surrogate markers of glucose utilization, proliferative activity, and amino acid transport and protein biosynthesis. Immediately after the PET/CT scan, animals were sacrificed for autoradiography, histologic work-up, or RNA expression analysis. Results: EAE lesions were predominantly located in the spinal cord. With MRI, we were able to detect inflammatory lesions in diseased rats, which correlated well with inflammatory infiltrates as determined by histology. Increased 18F-FDG uptake was observed in spinal cord lesions in all diseased rats. Further investigation by volume-of-interest analysis demonstrated a correlation between the density of histologically proven cellular infiltrates and the 18F-FDG signal intensity in PET (FDF=3 = 5.9, P = 0.001) and autoradiography (FDF=3 = 4.2, P = 0.008). With 18F-FET and 18F-FLT, no definite uptake could be observed on PET scans, whereas autoradiography showed slight radiotracer accumulation in some lesions. Conclusion: Spinal cord inflammatory lesions in the EAE model can be noninvasively visualized in vivo using MRI and 18F-FDG PET/CT. Localized 18F-FDG uptake correlates better with a histologically proven abundance of inflammatory cells as a critical marker of disease activity than MRI. Neither 18F-FET nor 18F-FLT seems to be a suitable marker for the in vivo detection of inflammatory lesions.