gms | German Medical Science

MRI issued to exclude other causes of intracranial hypertension and to show typical features, which can aid in the diagnosis of ICH. Previous described typical findings are:

• Dilated optic nerve sheath
• Dilated Meckel´s cave
• Empty sella
• Flattened optic bulbs
• Prominent optic nerve papilla
• Occlusion or stenosis of venous sinus

These findings should not be confused with classic intracranial hypertension due to tumorous lesions. Because ophthalmological and general clinical examinations may not lead alone to the diagnosis of IHC,MRI and MRA offer additional value.

For imaging ICH patients a standard brain protocol appears insufficient, because thin coronal (T2 weighted) slices are mandatory. The use of iv contrast media is less important. Fixing eye movement helps to reduce motion artifacts.

Several studies focussed on Optic nerve sheath diameter using ultrasound and MRI. Standard values were found and defined, but differ between different investigators. The judgement of all characteristics(listed above) together by an experienced observer appears more reasonable.

Also, the results from studies regarding the measurement of „empty sella“ are not easily comparable, due to measurement of osseous sella or pituitary gland with different 2D and 3D methods.

The features: Meckel´s cave, flattened bulbs and swollen papilla were proved to be less reliable.

The imaging of the venous dural sinus is more important. There is a disagreement between investigators whether sinus pathology represents cause or sequel of ICH. We suppose both can be observed, but normal venous sinus in ICH patients are very rare. The proof of sinus pathology is prerequisite for invasive treatment.

Many MR-angiography techniques, with and without iv contrast media, are available: Time of Flight, Phase-Contrast, Spin-labeling, pulse triggered subtraction, ….

We propose 3D phase-contrast-MRA as method of choice, because no iv injection is necessary, high resolution images are obtained, pure flow images can be reconstructed and slow flow can be made visible if correct velocity encoding is used (egVenc<= 10 cm/sec).Using advanced techniques quantitative flow measurements are possible.

Typical pitfalls in the diagnosis of sinus-occlusion or -stenosis are variants like Sinus occipitalis and physiologic Pacchioni granulations.