Computerized Tomography of the Posterior Fossa and the Upper Cervical Spine

Abstract

In spite of the diagnostic advantages of computerized tomography (CT), the posterior fossa and the upper cervical spine remain the most difficult regions to examine. Exact diagnosis is of utmost importance for the right choice of therapy (3). There has already been some improvement in the more recent CT scanners. Thus, it is now possible to extend the examination to the facial skull and the upper spine, water-coupling is no longer necessary, the scan and reconstruction time is much shorter, and the technical methods are much more variable. It is very important that the tentorium is clearly visible so that tumors can be shown in their actual connection to it. This applies, for example, to meningeomas and aneurysms so that the proper invasive neuroradiologic examination can be undertaken. The diagnostic results of the CT examinations are often limited by the difficulties presented by the Hounsfiled line and other artifacts in the regions under the tentorium. Therefore, it is, for example, very often difficult to decide whether or not there is a small acoustic neuroma in the cerebellar pontine angle. If the densities of the various tissues vary sufficiently, they can be shown on the CT without difficulty. Thus, it is no problem to differentiate CSF, cysts, or tumors of high density (e.g., cylindroma) growing from the mandibular angle to the posterior fossa through the foramen magnum.