Fig. 9.

a–c CT for the assessment of spondylolysis: for the reverse gantry technique as performed on single slice scanners the imaging plane is chosen in the plane of the posterior elements (a). The high in plane resolution allows for good assessment of bony continuity (b). However once the gantry is tilted spiral acquisition is no longer possible. This technique is obsolete for MD-CT where real-time 3D reformatting allows to chose the image plane to optimally display the lesion, in this case spondylolysis of L4 and L5 (c)