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Ga-68 FAPI Uptake in a Case of Recurrent Glioblastoma Multiforme
, Nishikant Avinash Damle1,, Amandeep Kumar2, Yamini Dharmashaktu1, Madhavi Tripathi1, Shamim Ahmed Shamim1, Vivek Tandon2
*Corresponding author: Nishikant Avinash Damle, Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India. nkantdamle@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Bishnoi K, Damle NA, Kumar A, Dharmashaktu Y, Tripathi M, Shamim SA, et al. Ga-68 FAPI Uptake in a Case of Recurrent Glioblastoma Multiforme. Indian J Nucl Med doi: 10.25259/IJNM_146_25
Abstract
Glioblastoma multiforme (GBM) is an aggressive primary brain tumor with a high recurrence despite multimodal therapy. Magnetic resonance imaging done after treatment can be limited by radiation necrosis, while F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) suffers from high cortical background activity. We present the case of recurrent GBM in which Ga-68 Fibroblast Activation Protein Inhibitor (FAPI) PET/CT demonstrated intense uptake with higher tumor-to-background contrast compared with FDG PET/CT. This case demonstrates the diagnostic potential of FAPI imaging in recurrent GBM and highlights its emerging theranostic relevance as a biomarker for FAPI-targeted radionuclide therapy.
Keywords
Fibroblast activation protein inhibitor
Fluorodeoxyglucose
Glioblastoma
Molecular imaging
Theranostics
A 44-year-old male presented 1 year ago with complaints of headache and vomiting. Magnetic resonance imaging (MRI) revealed a well-circumscribed, lobulated, heterogeneously enhancing lesion in the left frontotemporal region with associated peri-lesional edema, suggesting neoplastic etiology. He underwent left frontotemporo-parietal craniotomy with decompression. Histopathology findings of the lesion were suggestive of grade IV glioma, with immunohistochemistry showing O6-methylguanineDNA methyltransferase promoter methylation positive, isocitrate dehydrogenase (IDH) not detected (IDH1 and IDH2) status. Following the diagnosis, he received external beam radiotherapy (60 Gy in 30 fractions) with concurrent temozolomide. Post 5 months of therapy, the patient developed recurrent headaches and episodes of vomiting. MRI suggested residual/recurrent disease, and a second-line chemotherapy with etoposide, carboplatin, and bevacizumab was initiated. However, disease progression ensued with worsening right-sided weakness and right temporal vision loss.
The biological rationale is that tumor-associated fibroblasts in the extracellular stroma of glioblastoma overexpress fibroblast activation protein (FAP), whereas normal brain parenchyma shows negligible FAP expression.[1] This underpins the superior diagnostic performance of FAP Inhibitor (FAPI) positron emission tomography/computed tomography (PET/CT) compared with fluorodeoxyglucose (FDG) PET/CT.[2,3] This is supported by early clinical results, which show enhanced tumor conspicuity and diagnostic confidence in glioblastoma.[4,5] In addition to imaging, FAPI offers a theranostic potential, as the same ligand can be labeled with therapeutic radionuclides, such as Lu-177 and Y-90, for targeted radionuclide therapy, which broadens its use in neuro-oncology.[6]
This case highlights the incremental diagnostic and theranostic value of Ga-68 FAPI PET/CT in recurrent Glioblastoma multiforme [Fig 1], demonstrating its superior performance over FDG PET/CT for lesion delineation, and thus having a potential role in patient management.
- (a-c) F-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) demonstrated tracer uptake in an irregular, ill-defined mass lesion (blue arrows in a and b) involving the left fronto-parieto-temporal region, extending medially to involve the left periventricular and capsulo-thalamic region, abutting the posterior horn of the left ventricle. However, there was high background physiologic cortical uptake. In contrast, (d-f) Ga-68 fibroblast activation protein inhibitor PET/CT revealed intense, well-demarcated tracer uptake in the same lesion (red arrows in d and e), offering high lesion-to-background contrast and clear delineation of the tumor
Author contributions:
KB: Clinical input, image Analysis, data curation, literature review, manuscript writing – review, editing and approval; NAD: Concept and design, clinical input, image interpretation, manuscript review and approval; AK, YD, MT, SAS and VT: Clinical and surgical input, manuscript review and approval.
Ethical approval:
Institutional Review Board approval is not required.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for their images and other clinical information to be reported in the journal. The patient understand that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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