¹⁸F-ML-10 as a PET tracer for apoptosis imaging in target definition of stereotactic radiotherapy for patients with intracranial tumors

Objective To investigate the performance of¹⁸F-labeled 2-(5-fluoropentyl)-2-methyl malonic acid (¹⁸F-ML-10), a novel PET radiotracer for apoptosis, as a tool for delineating the target in the stereotactic radiotherapy (SRS) treatment plan. Methods The¹⁸F-ML-10 PET-CT images of 20 cases with intracranial tumors who would undergo stereotatic radiotherapy (X-Knife) were collected from January 1, 2014 to December 31, 2015 in Chinese PLA General Hospital before the start of the treatment.Gross tumor volumes (GTV) were delineated with Cyber Knife Robotic Radiosurgery System (Multiplan 4.0.2) and MIM (6.5.4) software based on PET images and MRI, respectively, by radiation engineer and senior neurosurgeon.The acquired data sets of GTV were analyzed with SPSS software (19.0) and the similarity coefficient (Dice) was calculated by MIM software. Results Tumors could be displayed clearly by PET imaging of apoptosis with¹⁸F-ML-10 and the contrast was high enough to distinguish the pathological field from the normal filed.There was no statistical significance in volumes of GTV between two methods (t=-1.040, P=0.311), and the mean value of the similarity coefficient (Dice) was 0.72.The difference of similarity coefficient (Dice) between recurrence group (n=6) and initial treatment group was significant (U=10.5, P=0.009).The recurrence group showed lower similarity coefficient (Dice). Conclusion Integrated PET imaging of apoptosis with¹⁸F-ML-10 can improve the accuracy of target regions delineation, and it can clearly differentiate tumor from normal brain tissue.