Can Early Postoperative O-(2-18FFluoroethyl)-l-Tyrosine Positron Emission Tomography After Resection of Glioblastoma Predict the Location of Later Tumor Recurrence?

OBJECTIVE: Glioblastoma inevitably recurs despite aggressive therapy. Therefore, it would be helpful to predict the location of tumor recurrence from postoperative imaging to customize further treatment. O-(2-18Ffluoroethyl)-l-tyrosine (FET) positron emission tomography (PET) might be a helpful technique, because tumor tissue can be differentiated from normal brain tissue with high specificity. METHODS: Thirty-two consecutive patients with perioperative and follow-up imaging data available were included. On postoperative FET-PET, the tumor/normal brain (TTB) ratio around the resection cavity borders was measured. Increased TTB ratios were recorded and anatomically correlated with the site of later tumor recurrence. On postoperative magnetic resonance imaging (MRI), residual contrast-enhancing tumor correlated with the site of later tumor recurrence. RESULTS: Location of progression was predictable using MRI alone in 42% of patients by residual tumor on postoperative MRI. FET-PET was predictive in 25 patients by a clear hot spot at the site of later tumor recurrence. In 3 patients, it was partially predictive and in 4 was not predictive of the tumor recurrence location. One patient without any tracer uptake was recurrence free at the last follow-up examination. In contrast to the postoperative MRI results, tumor recurrence was found in 79% at a site of elevated TTB ratio on postoperative FET-PET. Therefore, the predictability of the tumor recurrence location using postoperative FET-PET was greater than that with MRI, and all cases predictable using MRI could have been predicted using FET-PET. CONCLUSIONS: Postoperative FET-PET can be helpful for planning subsequent therapy, such as repeat resection or radiotherapy, because tumor recurrence can be predicted with relatively greater sensitivity than with MRI alone.