Increased 68Ga-DOTATATE uptake in PET imaging discriminates meningioma and tumor-free tissue

Abstract

Meningiomas are known to express somatostatin receptor 2 (SSTR2). PET using the SSTR2 analog 68Ga-DOTATATE has recently been introduced for imaging of meningiomas. However, a systematic correlation between 68Ga-DOTATATE uptake, SSTR2 expression, and histology (including tumor-free scar tissue) is still lacking. For elucidation, we conducted this prospective study. Methods: Twenty-one adult patients with primary (n = 12) or recurrent (n = 9) meningiomas were prospectively enrolled. Preoperative MR imaging and 68Ga-DOTATATE PET scans were fused and used for a spatially precise neuronavigated tissue-sampling procedure during tumor resection. Histopathologic diagnosis included immunohistochemical determination of SSTR2 expression. At each individual sampling site, the maximum standardized uptake value (SUVmax) of 68Ga-DOTATATE was correlated with MR imaging findings, histology, and semiquantitative SSTR2 expression. Results: One hundred fifteen samples (81 tumor, 34 tumor-free) were obtained. There was a significant positive correlation between SUVmax and SSTR2 expression. Receiver-operating characteristic analysis revealed a threshold of 2.3 for SUVmax to discriminate between tumor and nontumoral tissue. Regarding the detection of tumor tissue, PET imaging showed a higher sensitivity (90% vs. 79%; P = 0.049), with specificity and positive predictive values similar to MR imaging, for both de novo and recurrent tumors. Conclusion: 68Ga-DOTATATE uptake correlates with SSTR2 expression and offers high diagnostic accuracy to delineate meningioma from tumor-free tissue even in recurrent tumors after previous therapy. Our findings substantiate an important role for 68Ga-DOTATATE PET in meningioma management.