Single-photon　emission　computed　tomography　combined　with　micro-CT　(SPECT/mu　CT)　imaging　using　Nanobodies　against　complement　receptor　of　the　Ig　superfamily　(CRIg),　found　on　tissue　macrophages　such　as　synovial　macrophages,　has　promising　potential　to　visualize　joint　inflammation　in　experimental　arthritis.　Here,　we　further　addressed　the　specificity　and　assessed　the　potential　for　arthritis　monitoring.　Signals　obtained　with　Tc-99m-labelled　NbV4m119　Nanobody　were　compared　in　joints　of　wild　type　(WT)　versus　CRIg(-/-)　mice　with　collagen-induced　arthritis　(CIA)　or　K/BxN　serum　transfer-induced　arthritis　(STIA).　In　addition,　SPECT/mu　CT　imaging　was　used　to　investigate　arthritis　development　in　STIA　and　in　CIA　under　dexamethasone　treatment.　Tc-99m-NbV4m119　accumulated　in　inflamed　joints　of　WT,　but　not　CRIg(-/-)　mice　with　CIA　and　STIA.　Development　and　spontaneous　recovery　of　symptoms　in　STIA　was　reflected　in　initially　increased　and　subsequently　reduced　joint　accumulation　of　Tc-99m-NbV4m119.　Dexamethasone　treatment　of　CIA　mice　reduced　Tc-99m-NbV4m119　accumulation　as　compared　to　saline　control　in　most　joints　except　knees.　SPECT/mu　CT　imaging　with　Tc-99m-NbV4m119　allows　specific　assessment　of　inflammation　in　different　arthritis　models　and　provides　complementary　information　to　clinical　scoring　for　quantitatively　and　non-invasively　monitoring　the　pathological　process　and　the　efficacy　of　arthritis　treatment.