Long Term Follow-Up of Intra-Cranial Meningioma After Gamma Knife Radiosurgery

A PET and MRI investigation

H.-B. Sheu (許恆賓), 吳國海, 潘宏基, 劉仁賢, 郭萬祐

陽明大學放射醫學研究所

 

PET, a nuclear medicine procedure, is also known as a functional imaging

tool because its concentration has been found to be directly proportional to

many physiological parameters like blood flow, glucose metabolism, amino acid

production and etc. 

      Data from 6 subjects with intra-cranial meningioma, 2 male and 4 female, were used in this study.  All of these subjects had MRI and PET taken before, after and at regular intervals of 6 months or one year after gamma knife (GK) treatment. In this study we observed that patients with tumor volume sizes of < 5 ml and who received treatment with peripheral dose (PD) > 17Gy demonstrated adverse radiation effects (AREs) after 6 months.  The tumor volumes at this point reached its highest peak and started to drop to a size smaller than the pre-GK volume.  However, PET exhibited a decrease in concentration and stabilized thereafter.  For tumor volumes  > 10 ml AREs were also noted 6 months after GK treatment.  This included elevated MRI tumor volume and PET concentration.  In contrast to the earlier case mentioned, tumor volume size was highest at six months and decreased thereafter but the size did not go lower that the initial tumor volume.  As for PET, the concentration also increased at 6 months after treatment and decreased until it stabilized from that time on.

      Further studies have to be conducted to prove the validity of these observations reported here.