PT  - JOURNAL ARTICLE
AU  - Zhangjie Su
AU  - Federico Roncaroli
AU  - Pascal F. Durrenberger
AU  - David J. Coope
AU  - Konstantina Karabatsou
AU  - Rainer Hinz
AU  - Gerard Thompson
AU  - Federico E. Turkheimer
AU  - Karolina Janczar
AU  - Daniel Du Plessis
AU  - Andrew Brodbelt
AU  - Alan Jackson
AU  - Alexander Gerhard
AU  - Karl Herholz
TI  - The 18-kDa Mitochondrial Translocator Protein in Human Gliomas: An <sup>11</sup>C-(<em>R</em>)PK11195 PET Imaging and Neuropathology Study
AID  - 10.2967/jnumed.114.151621
DP  - 2015 Apr 01
TA  - Journal of Nuclear Medicine
PG  - 512--517
VI  - 56
IP  - 4
4099  - http://jnm.snmjournals.org/content/56/4/512.short
4100  - http://jnm.snmjournals.org/content/56/4/512.full
SO  - J Nucl Med2015 Apr 01; 56
AB  - The 18-kDa mitochondrial translocator protein (TSPO) is upregulated in high-grade astrocytomas and can be imaged by PET using the selective radiotracer 11C-(R)PK11195. We investigated 11C-(R)PK11195 binding in human gliomas and its relationship with TSPO expression in tumor tissue and glioma-associated microglia/macrophages (GAMs) within the tumors. Methods: Twenty-two glioma patients underwent dynamic 11C-(R)PK11195 PET scans and perfusion MR imaging acquisition. Parametric maps of 11C-(R)PK11195 binding potential (BPND) were generated. Coregistered MR/PET images were used to guide tumor biopsy. The tumor tissue was quantitatively assessed for TSPO expression and infiltration of GAMs using immunohistochemistry and double immunofluorescence. The imaging and histopathologic parameters were compared among different histotypes and grades and correlated with each other. Results: BPND of 11C-(R)PK11195 in high-grade gliomas was significantly higher than in low-grade astrocytomas and low-grade oligodendrogliomas. TSPO in gliomas was expressed predominantly by neoplastic cells, and its expression correlated positively with BPND in the tumors. GAMs only partially contributed to the overall TSPO expression within the tumors, and TSPO expression in GAMs did not correlate with tumor BPND. Conclusion: PET with 11C-(R)PK11195 in human gliomas predominantly reflects TSPO expression in tumor cells. It therefore has the potential to effectively stratify patients who are suitable for TSPO-targeted treatment.