Spinal and sacroiliac disorders, such as disc herniation, sacroiliitis, and spondylarthritis, require precise imaging for diagnosis. Conventional computed tomography (CT) is widely regarded as the reference standard for evaluating cortical bone and certain structural lesions due to its superior spatial resolution and accurate Hounsfield unit quantification, whereas MRI remains superior for marrow edema, soft tissue involvement, and early inflammatory changes. MRI-based synthetic CT (sCT) offers a radiation-free alternative by generating CT-like images from MRI data. This systematic review evaluates the diagnostic accuracy of sCT compared to conventional CT in these disorders. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) for diagnostic test accuracy studies (PRISMA-DTA) guidelines, we searched databases (PubMed, Embase, Cochrane, Scopus, Web of Science, CINAHL, IEEE Xplore) and gray literature. Eligible studies compared sCT to CT in patients with spinal/sacroiliac disorders, reporting metrics like sensitivity, specificity, and agreement. Two reviewers screened records, extracted data, and assessed risk of bias using QUADAS-2. Narrative synthesis was performed due to heterogeneity. Ten studies (n = 1028 participants) were included, focusing on degenerative spinal conditions and axial spondyloarthritis. sCT showed sensitivity of 47-94% and specificity of 83->95% for lesions (e.g., erosions, ankylosis), often superior to MRI and comparable to CT. Geometric measurements (e.g., vertebral dimensions) had high concordance (ICC = 0.788-0.978). Inter-observer agreement was moderate to excellent (κ = 0.41-0.98). Risk of bias was low in four studies but high in six, mainly due to small samples and selection issues. MRI-based sCT demonstrates promising diagnostic accuracy for spinal and sacroiliac disorders, potentially reducing radiation exposure. However, methodological limitations warrant larger, multicenter trials for validation.

Functional anatomic variants present a diagnostic challenge in the evaluation of hand pain. The Linburg-Comstock variation (LCV) is a connection between the flexor pollicis longus and the index and/or middle finger flexor digitorum profundus tendons. This variant connection can cause pain, termed "Linburg-Comstock syndrome," particularly in patients who perform repetitive hand-related activities such as musicians and manual laborers. Surgical correction of LCV relieves pain and facilitates enhanced precision, ease, and dexterity when gripping items. Magnetic resonance imaging (MRI) characterization prior to repair can reduce operative time and improve cosmesis. However, studies have not yet characterized the MRI findings in traumatic injuries to the LCV. We report a case of a 49-year-old woman with bilateral LCV who suffered an injury to the left wrist resulting in a partial tear of the LCV tendon. We discuss the MRI findings and how post-contrast imaging increased the conspicuity of the injured tendon. Surgical excision of the LCV led to an improvement in symptoms, and this case highlights the importance of recognizing LCV as a pain generator.

We report two bone-forming tumors driven by a newly recognized fusion. The first is a lesion in the distal radius of a 59-year-old female subject, which had been present for 10years. Imaging showed an intramedullary tumor with an exophytic dorsal component and marked sclerosis, histologically best classified as low-grade osteosarcoma. The second was a destructive lesion in the left ulna of a 13-year-old female with a short history of elbow pain. Imaging showed a lytic lesion with subtle tumor ossification, histologically best classified as an atypical osteoblastoma-like tumor. A NIPBL::BEND2 fusion was found in both cases on whole genome sequencing. This fusion has been previously reported in three bone lesions, two of which were reported as phosphaturic mesenchymal tumors and the other exhibited features of a high-grade osteosarcoma. These newly reported cases were bone-forming, but histologically indolent, with no features of high-grade osteosarcoma, and did not demonstrate the typical features of a phosphaturic mesenchymal tumor nor evidence of tumor-induced osteomalacia. The World Health Organization has not established a specific name for tumors associated with a NIPBL::BEND2 fusion, and their biological potential cannot currently be predicted. These cases add to the expanding clinical and histological knowledge of this entity and illustrate that, in addition to the other rarely reported phenotypes, low-grade bone-forming tumors may also be caused by this exceptionally rare fusion.