PET-CT tumor imaging with ⁶⁴CuCl₂: Early experience with brain tumor imaging

Background: Copper transporter receptor (CTR) have been postulated to be present only in high grade brain tumors/ Glioma. This knowledge obtained from imaging with Copper will further help to choose potential candidate for theragnostic therapy with other copper isotopes. We report preliminary evidence of ⁶⁴CuCl₂ uptake in various grades of brain tumors to aim towards this goal. Materials and methods: A prospective study was done on patients presented with suspected brain tumors based on MRI finding. After taking informed consent all patients were administered ⁶⁴CuCl₂(~175MBq) and brain positron emission tomography (PET)/computed tomography (CT) imaging was performed at 2 and 24 hours after administration. Standardized uptake values (SUV) were calculated. After imaging all patients advised for surgery and ⁶⁴CuCl₂ PET/CT imaging findings were correlated with MRI and HPE.

Results: Total 15 patients have been enrolled till now. Out of 15 patients, MRI was suggestive of high-grade brain tumor in 10, low grade in 4 and meningioma in 1 patient. Eight out of 15 patients showed ⁶⁴CuCl₂ uptake on PET/CT with variable SUVmax (1.4- 20). HPE were suggestive of low grade astrocytoma (2 patients, SUVmax- 1.4 and 3.5 at 2 and 24 hours), pilocytic astrocytoma (2 patients, SUVmax- 3.8 and 1.5 at 2 and 24 hours), anaplastic astrocytoma (2 patient, SUVmax- 11.1 and 20.0 at 2 and 24 hours), meningothelial meningioma(SUVmax- 10.3 and 5.17 at 2 and 24 hours) and atypical meningioma (SUVmax- 2.4 and 1.3 at 2 and 24 hours). In 7 patients with no uptake on PET-CT, HPE was available in 2 patients, which revealed anaplastic oligoastrocytoma and oligodendroglioma. For rest of the 5 patient, HPE was not available. Conclusion: This preliminary study suggests that ⁶⁴CuCl₂ is accumulating in some but not all high-grade brain tumors. There appears to variability in the grade of Copper uptake in all grades of tumors. More data is being accumulated to define the cutoff of copper uptake as potential differentiating features for identifying possible theragnostic targets.