Evaluation of tumor progression and detection of new tumors during repeat gamma knife ? stereotactic radiosurgery utilizing the co-registration tool in leksell gamma plan ?: Technical note

摘要

Background: Repeat Gamma Knife stereotactic radiosurgery (GKSR) procedures are becoming common, especially for brain metastases. It is important to identify tumors requiring treatment at repeat GKSR and it can be challenging to distinguish treated tumors, tumor progression and new tumors. Using the image co-registration tool within the Leksell Gamma Plan software, we developed a technique to aid in the identification of tumors needing treatment.Objectives: The objective was to explore a new co-registration technique to identify tumors requiring treatment at repeat GKSR procedures.Methods: Ten patients who underwent repeat GKSR for brain metastases were identified. Contrast-enhanced volumetric T 1 magnetic resonance images (MRI) from the previous GKSR were co-registered with the new images and the resulting two-color format image was used to evaluate tumor status.Results: Using the co-registered images, tumors were characterized as: resolved, regressed, stable, larger or new. Overall, 13.6% of tumors completely resolved, 26.2% regressed, 13.1% remained stable, while 7.9% progressed. Thirty-nine percent of tumors were new.Conclusions: The co-registration technique makes clinically relevant changes conspicuous on MRI. It distinguishes between tumors potentially requiring treatment and those that have been treated successfully. It can be used with tumors other than metastases and for evaluating tumor response at follow- up.