PARENCHYMAL NEUROCYSTICERCOSIS - FOLLOW-UP AND STAGING BY MRI

We describe the evolution of parenchymal cerebral cysticerci on MRI, t o assess signs of early cyst degeneration. We studied 15 lesions in fo ur treated and one untreated patient. MRI was performed before therapy and repeated in the 1st month after each course of anticysticercus dr ugs, every 4 months during the 1st year and then annually; the follow- up period was 8-48 months. Lesions were classified according to change s in four features: cyst content and capsule signal, gadolinium enhanc ement and oedema signal. We were able to recognise each of the patholo gical phases; five MRI stages were identified, Stage 1 showed oedema a nd/or nodular gadolinium enhancement in the tissue invasion phase; sta ge 2 was cerebrospinal fluid-like signal within a cyst in the vesicula r phase; stage 3 showed a thick capsule with an impure liquid content signal and surrounding oedema, in the cystic phase; stage 4 showed the disappearance of the cyst fluid content signal in the degenerative ph ase; stage 5 showed a calcified lesion in the residual phase. Stage 1 lesions disappeared after therapy; the other progressed from one stage to another. Stage 4 indicated the end of viability of the parasite an d determined the point after which treatment was useless. On T2-weight ed images changes in the cyst content differed according to the histor y of the lesion; nodular low intensity followed the natural degenerati on of the parasite and a mixed fluid signal with punctate low signal s eemed to represent the specific result of therapy. MRI staging can hel p in the evaluation of indications for treatment and facilitate clinic al therapeutic trials.