[Lacunar stroke as a very late complication of radiotherapy: value of nuclear medicine techniques]

Radiation therapy is a very useful treatment for central nervous systemS neoplasms. The time range of its complications is very wide; they appear even many years after its completion. These late complications behave clinically and radiologically similar to a relapse; a functional diagnostic study with radioactive isotopes can help to make a therapeutic decision.

A male suddenly presented deficient neurological symptoms in the same site where he received radiation therapy 25 years earlier for a pilocytic astrocytoma. The MRI findings suggested a lacunar stroke but a finding in the perfusion sequence forced us to be more precise in the diagnosis. A PET-CT 11C-methionine was performed which showed an increased uptake compatible with neoplasia. The spontaneous regressive evolution of the symptoms inclined us to take a conservative attitude. Lacunar ictus was confirmed on MRI three months later.

The reappearance of neurological symptoms years after radiotherapy of a brain neoplasm poses a diagnostic dilemma. Current diagnostic techniques are very accurate but present false positives. The various nuclear medicine techniques, in particular PET-CT 11C-methionine, are a diagnostic aid. With the presentation of this case we intend to draw attention to one of the late complications of radiation therapy and the various differential diagnoses. Diagnostic and therapeutic advances have increased the life expectancy of cancer patients, so these late complications are expected to be more frequent.