Fig. 1From: Value of SPECT-CT Imaging for Middle-Aged Patients with Chronic Anterior Knee PainSingle-photon emission computed tomography/computed tomography (SPECT/CT) uptake grading system for patella-femoral joint (patella grades shown). Grade 0 indicates no uptake (same as normal cancellous bone); grade 1, higher uptake than normal cancellous bone but lower than articular surface; grade 2, same uptake as articular surface; grade 3, higher uptake than articular surfaceBack to article page