Targeted four-dimensional computerized tomography scans for elbow disorders: a literature review and refinement of existing technique with two exemplar cases

Abstract

Background4D-CTs or motion CTs in elbow disorders have several potential advantages over conventional static imaging such as a reduction of misdiagnoses, a more targeted surgical approach, better patient understanding of their condition and potentially faster operative times. However, the radiation dose is higher than conventional static CT scans so this should be used judiciously. Our study reviews the current literature for 4D-CTs in dynamic elbow disorders and provides a technical note describing radiation-reduced targeted elbow 4D-CTs (te4D-CT) with two exemplar cases alongside our recommendations for when te4D-CTs are indicated. Methodste4D-CTs are performed in a lateral decubitus elbow above head position. Preliminary static source axial cut CT obtained with subsequent sagittal and axial planes reconstruction and 3D reconstruction obtained, followed by scan performed in motion and reconstructed to 4D Component. te4D-CTs are taken for either flexion and extension (FE) or pronation and supination (PS) motions depending on the clinical pathology suspected following thorough clinical examination. Resultste4D-CT for PS and FE protocol scans had an effective radiation exposure dose of 0.53 and 0.95mSv respectively compared to 1.13-1.83mSv in conventional elbow 4D-CTs. In addition, te4D-CTs have good diagnostic accuracy provided that the FE or PS pathology is identified carefully by the ordering physician. Conclusionte4D-CT using isolated pronation and supination, or flexion and extension protocols does come with a significantly reduced radiation dose and can be of equal clinical yield compared with 4D-CTs.