The Usefulness of Maximum Standardized Uptake Value of Quantitative Bone SPECT/CT in Patients with Medial Compartment Osteoarthritis of Knee

Objectives The aim of this study was to evaluate the usefulness of maximum standardized uptake value (SUVmax) from quantitative bone single-photon emission computed tomography/computed tomography (SPECT/CT) in the patients with medial compartment osteoarthritis (OA) of knee.

Methods The current retrospectively study enrolled 26 patients with medial compartment knee OA (55.3±5.8y, 2 male and 24 female) who had undergone quantitative SPECT/CT using Tc-99m hydroxymethylene diphosphonate (HDP) before high tibial osteotomy (HTO) or total knee replacement arthroplasty (TKRA). 34 operated (Op) knees (30 HTO and 4 TKRA) and 18 non-operated (non-Op) knees were included. SUVmax was obtained over medial, lateral and patellofemoral compartments using dedicated quantitative software. Visual grades of Tc-99m HDP uptake on the bone SPECT/T and Kellgren-Lawrence (KL) osteoarthritis scores on the plain radiographs were assessed by the respective experts using 5-point scale (0, no abnormal; 1, mild-; 2, moderate-; 3, severe-; and 4, intense abnormal). The difference of SUVmax between Op knees and non-Op knees were compared using Mann-Whitney test. The Spearman’s correlations were investigated among SUVmax, visual grade of SPECT/CT and KL score.

Results The Op knees (n=34) had significantly greater SUVmax than the non-Op knees (n=18) in medial (14.1±6.1 vs.5.3±4.4, p<0.0001) and lateral (6.7±3.1 vs. 4.9±4.4, p=0.0004) compartments, but there was no significant difference of SUVmax in patellofemoral compartment (6.1±2.9 vs. 6.8±6.7, p=0.1975). SUVmax and visual grade were significantly correlated in medial (r=0.463, p=0.0059) and patellofemoral (r=0.507, p=0.0022) compartments but not in lateral (r=0.320, p=0.0650) compartment. SUVmax was also significantly correlated with KL score in medial compartment (r=0.454, p=0.0070) but not in lateral (r=0.0810, p=0.6524) and patellofemoral (r=0.306, p=0.0787) compartments.

Conclusions In the current study, we demonstrate that SUVmax from the quantitative bone SPECT/CT is highly associated with visual assessment of Tc-99m HDP uptake and radiographic abnormalities. Quantitative bone SPECT/CT is a promising imaging modality for objective assessment of medial compartment knee OA.