Application Of MRI Coregistration With PET On Brain Biopsy And Quantitative Volumetric Analysis Of Glioblastoma

Objective: To explore the clinical value of intraoperative magnetic resonance imaging coregistrating with position emission tomography/computed tomography in stereotactic brain biopsy. To investigate the relationship between three-dimensional volumetric data of the metabolically active tumor volume assessed using positron emission tomography and the area of enhancement magnetic resonance imaging in patients with newly diagnosed glioblastoma.Methods: Part Ⅰ: Forty nine patients with intracranial lesions were operated by stereotactic biopsy from June 2010 to June 2015 in Tianjin Medical University General Hospital. Seventeen patient’s operation was guided by MRI only(group A), thirty two patients’ operation was guided by MRI and PET/CT(group B). Compare the diagnosis success rate and operation related complications between the two groups. Part Ⅱ: PET and enhanced MRI with were performed in 5 patients with newly diagnosed GBM from October 2015 to February 2016. To calculate the volumes in cubic centimeters, a threshold-based volume-of interest(VOI) analysis of the metabolically active tumor volume(uptake indexes of ≥1.3 and ≥1.5) and of the area of MRI enhancement was performed after coregistration of all images, as well as the overlay area between the metabolically active tumor volume and MRI enhancement, and the PET high uptake regions beyond MRI enhancement. Compare the lesion distribution in PET and MRI enhancement.Results: Part Ⅰ: PET/CT and MRI were integrated successfully in all cases of group B. Fourteen patients(82.4%) of group A and all 32 patients(100%) of group B had final diagnosis confirmed by histopathological and immunohistochemically observation. The diagnosis success rate of group B is higher than group A(P<0.05). There are 5 patients in total who have postoperative complication, 2(11.8%) for group A and 3(9.3%) for group B, but the difference was not statistically significant. Part Ⅱ : All five patients were confirmed as glioblastoma multiforme by histopathological diagnosis. The metabolically active tumor volume as shown using a MET uptake index of ≥1.3 was larger than the volume of MRI enhancement, the percentage of overlay area in total MRI enhancement volume was 73%~90%, the percentage of metabolically active tumor volumes beyond MRI enhancement was 35~63%. As for the index of ≥1.5, the metabolically active tumor volume in MET was larger than the volume of MRI enhancement too, the percentage of overlay area in total MRI enhancement volume was 67~88%, the percentage of metabolically active tumor volumes beyond MRI enhancement was 33~61%. There is significant difference and variability in the metabolically active tumor volume as shown using FDG; it doesn’t fit for quantitative analysis.Conclusion:(1) PET/CT based metabolic imaging can be integrated with enhanced MRI guided stereotactic biopsy. It’s a safe and effective method to improve diagnosis yield, develop patient-tailored therapy strategies without increase complications.(2) The present data suggest that in patients with newly diagnosed GBM the majority of MRI enhancement overlapped with the metabolically active tumor volume in MET-PET, image of MET is eccentric from the overall visual.(3) The percentage of metabolically active tumor volumes in MET beyond MRI enhancement can be measured throught quantitative volumetric analysis, so that it can define tumor bourndary and assist to decide extent of resection.(4) There is limited value of FDG in delineating glioblastoma lesion extent.