- Systematic approach of assessing posteirior cranial fossa on CT scan. - Review of commonly missed pathology within this region. - Overview of pitfalls within the posterior cranial fossa.

Posterior cranial fossa is located between the foramen magnum and the tentorium cerebelli. Posterior cranial fossa of a CT head is like a ‘blind spot’ where most pathology is missed due to the increased beam-hardening artefact within this region. This crucial area is where interpreting Radiologists are most prone to perceptual errors.[1]Having a comprehensive checklist and a routine approach is therefore paramount in order to avoid false negative results and achieve high quality diagnostic reporting.

Different windowing options apart from standard brain window are available such as narrower subdural, bone and soft tissue windows should be viewed in all planes. Looking for grey white matter differentiation and CSF spaces are mandatory in all planes. Systematic approach of posterior cranial fossa on various views is listed below: Axial -Midbrain: vermis, cisterns - quadragerminal and interpeduncular cisterns, superior saggital sinus -Pons - CP angle, transverse and sigmoid sinus, inner ear ossicles, cisterns – prepontine and fourth ventricle, mastoid air cells – mastoiditis...

Assessment of posterior cranial fossa is compromised primarily due to beam hardening artefact and therefore by having a routine checklist, perceptual errors can be greatly minimized and have a positive impact on the patient.

1.Bahrami, S. And Yim, C.M. Quality Initiatives: Blind Spots at Brain Imaging, Radiographics, 2009. 2.Meenakshisundaram, N.Posterior cranial fossa space occupying lesions: an institutional experience. International Journal of Research in medical sciences; 2018.