ABSTRACT

In order to determine the etiology of chronic pain, radiological imaging tools like computed tomography (CT) and magnetic resonance imaging (MRI) are usually used. Except for the anatomical data that the radiological imaging methods provide, there are nuclear medicine imaging methods like bone scintigraphy and positron emission tomography (PET) which are used to demonstrate metabolic changes in the bone, joint and neighbouring soft tissue which may cause pain. Recently, hybrid imaging methods combining anatomical and metabolic imaging like single photon emission computed tomography (SPECT)/CT and PET/MR have been introduced. In the last decades, imaging with higher resolution and providing anatomical localisation have been possible thanks to bone scintigraphy performed with hybrid SPECT/CT. This is why clinical studies have been performed especially about the role of bone SPECT/CT in the evaluation of pain originating from vertebra. The major limitation of the studies with bone SPECT/CT is that the uptake of radiopharmaceutical is limited to increase in osteoblastic activity and that changes like inflammation cannot be diagnosed. So, PET imaging combined with MR and performed with radiopharmaceuticals imaging different metabolic pathways come forward. PET/MR studies performed with the most commonly used radiopharmaceutical, F-18-FDG, come first among the studies on PET/MR in pain imaging. While F-18-FDG PET/MR imaging provides anatomical abnormalities of the joint with MRI component and hypermetabolic/inflammatory pathologies with PET component, it is a promising imaging tool for diagnosing the causes of chronic pain. Another PET radiopharmaceutical in pain imaging is F-18-sodyum fluoride (NaF). However, data about its use in degenerative bone diseases is limited. It has been reported that metabolic changes can be detected before MRI changes appear. Sigma-1 receptor (S1R) is especially localized in the endoplasmic reticulum as a signal modulating receptor which plays role in the pathophysiology of many neurological diseases, mainly neuropathic pain, is found extensively in the central nervous system. F-18- FTC-146 [6-(3-(18F)fluoropropyl)-3-(2-(azepan-1)ethyl)benzo(d)thiazol-2] is a radiopharmaceutical which targets this receptor and binds with high affinity. Because it is a very recently developed radiopharmaceutical, the available findings are needed to be supported by further clinical trials. Already existing results show that this imaging method is a promising tool in pain imaging.