In Reply

The current S2k guideline on rhinosinusitis recommends computed tomography as the standard procedure for the diagnostic evaluation of chronic rhinosinusitis: “In the context of the diagnostic evaluation of chronic rhinosinusitis (CRS), low-dose CT is the examination technique of choice as the imaging diagnostic evaluation, alternative digital volume tomography (DVT)” can be used. Furthermore, “the group of DVTs is heterogenous; there are notable qualitative differences between the individual devices (resolution, time taken by the examination, and dose)”. Both modalities are therefore suitable for exposing anatomical structures. They are discussed accordingly in the guideline and we included them in our article ([1]), pages 34, 35). The drawback of DVT lies in the fact that soft tissue processes—for example, an intraorbital abscess—cannot be exposed in the same way as on CT, which means that DVT is suitable only in the high-contrast range to expose bone structures (2).

If intracranial complications are suspected, low-dose CT or DVT is not sufficient. In this setting, CT using contrast medium or magnetic resonance imaging (MRI) is necessary. We can confirm the comment by Cohnen et al that recently, increasing numbers of studies have been published of using MRI in orbital complications especially in children. In this setting, MRI is equivalent or even superior to contrast medium CT as regards the detection and determination of the extent of endocranial complications, but also of orbital abscesses (3, 4). The disadvantage of MRI is a less good exposure of bony structures. Exposing the bone anatomy is, however, indispensable when planning surgery (2). Additionally, an MRI scanner may be less easily available than a CT scanner, and MRI requires sedation when examining small children.