Protrusion adjustment rings can be used to with compatible imaging cannulas to avoid the use of excessive dental cement during the cannula implantation process by creating an adjustable support between the base of the cannula and the skull. A set of protrusion adjustment rings of different heights is available to adjust the cannula to the height corresponding to the desired imaged brain region. By combining an imaging cannula model L with the right protrusion adjustment ring, it is possible to cover most parts of the brain. The height of the rings is 2.0 mm, 2.7 mm, 3.4 mm, 4.2 mm and 4.9 mm. Within the set, there are 8 rings for each height.

For the model S, one protrusion adjustment ring (height of 4.5 mm) is sufficient to image the brain from the surface to 1.1 mm deep. The set is composed of 10 identical rings.

Note: The protrusion of the adjustment ring (p) is given by : p = L - d and corresponds to a specific ring set (see table and figure).