Unintended Consequences: Review of New Artifacts Introduced by Iterative Reconstruction CT Metal Artifact Reduction in Spine Imaging.

Metal hardware serves as a common artifact source in spine CT imaging in the form of beam-hardening, photon starvation, and streaking. Postprocessing metal artifact reduction techniques have been developed to decrease these artifacts, which has been proved to improve visualization of soft-tissue structures and increase diagnostic confidence. However, metal artifact reduction reconstruction introduces its own novel artifacts that can mimic pathology.

Metaphyseal fractures mimicking abuse during treatment for clubfoot.

BACKGROUND: Metaphyseal injuries resembling the classic metaphyseal lesion (CML) of abuse may occur as the result of serial casting during treatment of clubfoot deformity. Mentioned in the orthopedic literature in 1972, this iatrogenic fracture has not been described in the radiologic literature nor has the similarity to injuries occurring with abuse been previously recognized. OBJECTIVE: To describe the mechanism and radiographic appearance of metaphyseal injury observed during serial casting of clubfoot. Note similarities to the CML of abuse. MATERIALS AND METHODS: Eight children ranging in age from 1 to 4 months underwent casting for clubfoot. Five orthopedic surgeons from three different institutions performed the casting. Two patients had spina bifida and one, arthrogryposis. A complete skeletal survey was performed on one child who was abused; there was no suspicion of abuse in the remaining seven. RESULTS: All children manifest injury with periosteal new bone. One child had clear evidence of abuse with 24 rib fractures. X-rays of lower extremities in short leg casts revealed bilateral tibial metaphyseal fractures. Four other children had metaphyseal fractures resembling the CML of abuse, and three developed an area of sclerosis within the metaphysis. CONCLUSION: In the setting of serial casting for equinovarus deformity, metaphyseal injury even the CML of abuse may be noted. Since inflicted injuries are almost always unobserved and explanations rarely offered, the fact that the CML occurs as a result of orthopedic maniuplation may offer some further insight concerning the pathogenesis of this well-described abuse injury.