The Added Value of Bloodpool SPECT/CT in Painful Non-Operated Foot and Ankle Undiagnosed With Standard Three-Phase Bone Scintigraphy

Abstract

Purpose: To evaluate the interest of adding a bloodpool SPECT/CT to standard three-phase bone scintigraphy (BS) for etiological diagnosis of subacute and chronic lower extremity pains. Methods: We prospectively included patients addressed for pain of lower extremities lasting for at least 6 weeks, without previous surgery. They underwent a standard three-phase BS including late phase SPECT/CT, modified with an additional bloodpool SPECT/CT acquisition. Two independent physicians interpreted the images provided by both protocols. Diagnostic conclusion, diagnostic confidence, and interrater agreements were compared. Results: One hundred and eighteen lower extremities from 113 patients were analyzed (71 men, median age of 53 years). Adding bloodpool SPECT/CT to standard three-phase BS changed diagnostic conclusions in 24.6% (29/118) of lower extremities. The modified protocol revealed at least one diagnostic conclusion explaining the pain in 89% of extremities, rather than 83.1% with the standard protocol (p = 0.02). Tendinopathies were diagnosed in 12.7% of lower extremities, rather than 4.2% with standard BS (p = 0.002). Adding bloodpool SPECT/CT substantially increased overall confidence of each reader (p < 0.001). Inter-reader agreement was not significantly impacted. Conclusion: Adding bloodpool SPECT/CT to standard three-phase BS impacted diagnostic conclusion in a quarter of the patients with painful lower extremities, notably by revealing significantly more tendonitis.

Keywords: ankle; bloodpool SPECT; bone scintigraphy; early SPECT/CT; foot.

Figure 1

Flowchart of the study.

Figure 2

Images of three-phase bone scintigraphy from three patients with right lower extremity pain, including images provided by bloodpool SPECT/CT (in orange boxes). Patient (A) was a 62-year-old man referred for suspicion of right lateral malleolus stress fracture. Bloodpool SPECT/CT revealed intense uptake along peroneal tendons, highly suggesting the diagnosis of right peroneal tendonitis. Patient (B) was an 81-year-old woman with pain of the right ankle and anterior tarsus, suspected with stress fracture. Bloodpool SPECT/CT revealed focal uptake at the insertion of the anterior tibial tendon, leading to set the diagnosis of right tibial anterior tendonitis. Patient (C) was a 60-year-old woman, suffering from right medial ankle pain. Planar bloodpool and late phase SPECT/CT images were compatible with a posterior tibial tendonitis with a low diagnostic confidence. Bloodpool SPECT/CT substantially increased the diagnostic confidence for posterior tibial tendonitis and revealed intense focal uptake at the insertion of the anterior tibial tendon, evocative of associated right tibial anterior tendonitis.

Figure 3

50-year-old man suffering from pain of third to fifth left metatarsus. Anterior (A) and posterior (B) planar bloodpool images suggested increased uptake in the projection of left and right midfoot. Bloodpool SPECT (C: MIP, D: SPECT fused VRT and anatomical drawing) refuted the “abnormality,” revealing physiological linear uptake on deep plantar arch.