128 Part I Chapter 5 In foot and ankle pathology, some literature has emerged with promising results for bone-SPECT/CT . However, specifically in patients with TCs, the exact role of bone-SPECT/CT in clinical work-up and relation to other (radiological) imaging modalities is still unknown. Molecular and multimodality imaging in tarsal coalitions Bone scintigraphy including bone-SPECT using [99mTc]Tc-diphosphonate agents sensitively image in vivo osteoblast activity with high sensitivity for early detection of pathophysiological changes of bone remodeling, before anatomical changes occur . The CT-component of bone-SPECT/CT is useful as it not only improves the signal of bone-SPECT by attenuation correction, it also localizes the focus of increased [99mTc]Tc-diphosphonate uptake precisely and in longer-existing pathology, the CT may reveal the anatomical changes and in this way improve specificity of the finding. Bone-SPECT/CT is an established problem-solving modality in patients with foot and ankle pathology, with high sensitivity for the detection of osteoblastic activity in various bone and joint diseases and with generally high correlation of osteoblastic activity to pain complaints in many bone and joint disorders . However, specific literature is still limited about findings on bone-SPECT/CT in patients with TCs, with one specific case report that we are aware of , and the rest being more generalized overviews on foot and ankle pain, without specific focus on TCs [15, 18-20] or with little consideration of molecular imaging [7, 8, 14]. The role of bone-SPECT/ CT in TCs has not yet been described in a review format in relation to other imaging techniques and clinical outcome. On bone scintigraphy, a TC is usually projected on early phase imaging 5 minutes post-injection as focal increased [99mTc]Tc-diphosphonate activity in the region of the hind- and midfoot indicating increased focal blood pool, followed 4 hours later postinjection by focal strongly increased bone turnover in the same area in an otherwise normal uptake pattern elsewhere (Figure 4, panel A). Lastly, also positron emission tomography with integrated computed tomography using sodium fluoride-18 (Na[18F]F PET/CT) is able to image bone turnover in bone and joint disease, which works in several ways similar to bone-SPECT/CT [16, 21], but this technique is outside the scope of current article.