Central nervous system disorders

II./3.3.: Differential diagnostic questions

Certain non-tumorous laesions might demonstrate such morphological, density and signal characteristics as the tumors, and mimic tumors by their contrast uptake behavior (see there). Sometimes only MR spectroscopy (MRS) provides confidence.

Differencial diagnostic problem can be caused by the postirradiation necrosis which can present a space occupying effect, its borders are poorly defined. Signal intensity is moderate or low on T1, and moderate or high on T2. It is very confusing if enhancement is present. It can develop half year or so after the irradiation and last even for 10 years. Sometimes only PET or MRS can differentiate them. Awareness is necessary and a basis investigation including a DWI as well must be performed immediately following irradiation which can be followed up during the course.