123 Review of the role of bone-SPECT/CT in tarsal coalitions Clinical context and dilemmas In TC, the bridge between the bones is initially fibrous, then gradually becomes cartilaginous, and might eventually ossify. In symptomatic TC-patients, pain complaints usually arise at 8 to 16 years of age, around the time of ossification of the coalition [3]. Commonly, nonoperative/conservative treatment is effective and can prevent surgery (79% in CNC and 62% in TCC) or delay the need for operation [4]. Conservative treatment consists of intermittent immobilization using a walking boot for six weeks, followed by supportive measures (longitudinal arch supports with ankle strengthening), continuous immobilization via casting or orthopedic footwear, nonsteroidal anti-inflammatory medications, intra-articular steroid injection, or activity modification [4, 5]. TCmay result in a rigid flat foot deformity (pes planus). The differential diagnosis of rigid flat foot deformity includes tarsal coalition, neurogenic planovalgus, and peroneal spasticity [6]. Paediatric or adolescent ankle pain is often initially mistaken for a common ankle sprain in initial evaluation, while an underlying tarsal coalition or other pathology, such as juvenile idiopathic arthritis, osteochondritis dissecans of the talus, hereditary sensory motor neuropathy, or transitional ankle fractures, might be the true cause [2]. Surgery may involve resection for both CNC and TCC and for large TCC fusion may be considered including concomitant planovalgus reconstruction [4, 6]. In case of indicated operative treatment, effective pain reduction benefits from pinpointing the culprit pain generator site, which impacts the choice of therapeutic intervention. Conventional imaging in tarsal coalitions, including issues and limitations In patients presenting with foot pain, appropriate imaging is needed for definitive diagnosis, startingwith plain radiographs of the foot [7]. In fibrous coalitions, irregularity and narrowing of the bony interfaces can be seen, often with associated sclerosis and/ or unusual orientation of the articulation. In case of CNC, radiographs should include 45 degrees oblique and lateral views [7]. Although the anteater nose sign, which is the extending of the anterior process of the calcaneus beyond the calcaneocuboid joint on radiographs (Figure 1), is highly specific for CNC with specificity of 94% [7], plain radiographs do not exclude a CNC due to the limited sensitivity of 72% [7]. Especially TCC may demonstrate a bony bar in bony coalition and short neck of the talus or “beaking”, being the radiological superior projection of the distal aspect of the talus on 5