High-resolution CT with histopathological correlates of the classic metaphyseal lesion of infant abuse.

Background: The classic metaphyseal lesion (CML) is a common high specificity indicator of infant abuse and its imaging features have been correlated histopathologically in infant fatalities.

Objective: High-resolution CT imaging and histologic correlates were employed to (1) characterize the normal infant anatomy surrounding the chondro-osseous junction, and (2) confirm the 3-D model of the CML previously inferred from planar radiography and histopathology.

Materials And Methods: Long bone specimens from 5 fatally abused infants, whose skeletal survey showed definite or suspected CMLs, were studied postmortem. After skeletal survey, selected specimens were resected and imaged with high-resolution digital radiography. They were then scanned with micro-CT (isotropic resolution of 45 μm(3)) or with high-resolution flat-panel CT (isotropic resolutions of 200 μm(3)). Visualization of the bony structures was carried out using image enhancement, segmentation and isosurface extraction, together with volume rendering and multiplanar reformatting. These findings were then correlated with histopathology.

Results: Study of normal infant bone clarifies the 3-D morphology of the subperiosteal bone collar (SPBC) and the radiographic zone of provisional calcification (ZPC). Studies on specimens with CML confirm that this lesion is a fracture extending in a planar fashion through the metaphysis, separating a mineralized fragment. This disk-like mineralized fragment has two components: (1) a thick peripheral component encompassing the SPBC; and (2) a thin central component comprised predominantly of the radiologic ZPC. By manipulating the 3-D model, the varying appearances of the CML are displayed.

Conclusion: High-resolution CT coupled with histopathology provides elucidation of the morphology of the CML, a strong indicator of infant abuse. This new information may prove useful in assessing the biomechanical factors that produce this strong indicator of abusive assaults in infants.