Perfusion-sensitive MRI of pilocytic astrocytomas: initial results.

PURPOSE

To present the imaging and perfusion data obtained in nine patients with pilocytic astrocytomas (PA) and to discuss the original functional issues of this technique.

METHOD

Nine patients with pathologically proven PA underwent conventional and perfusion MR imaging. Various areas of relative cerebral blood volume (rCBV) within the tumors were obtained. The maximum rCBV ratios were identified and considered as representative of the tumor. The results were compared with the pathological findings.

RESULTS

In all patients, rCBV was <1.5 (mean 1) and the signal intensity curve overshot the baseline.

CONCLUSION

PA tend to have low rCBV values and a first-pass curve that crosses the baseline. These characteristics may be explained by the histological profile of the tumoral vascularity and are of relevance in the identification of these rare tumors.