Tumor hypoxia and microscopic diffusion capacity in brain tumors: a comparison of (62)Cu-Diacetyl-Bis (N4-Methylthiosemicarbazone) PET/CT and diffusion-weighted MR imaging.

OBJECTIVE

The aim of this study was to clarify the relationship between tumor hypoxia and microscopic diffusion capacity in primary brain tumors using (62)Cu-Diacetyl-Bis (N4-Methylthiosemicarbazone) ((62)Cu-ATSM) PET/CT and diffusion-weighted MR imaging (DWI).

METHODS

This study was approved by the institutional human research committee and was HIPAA compliant, and informed consent was obtained from all patients. (62)Cu-ATSM PET/CT and DWI were performed in a total of 40 primary brain tumors of 34 patients with low grade glioma (LGG, n = 13), glioblastoma (GBM, n = 20), and primary central nervous system lymphoma (PCNSL, n = 7). (62)Cu-ATSM PET/CT parameters and apparent diffusion coefficient (ADC) obtained by DWI were compared.

RESULTS

High intensity signals by (62)Cu-ATSM PET/CT and DWI in patients with GBM and PCNSL, and low intensity signals in LGG patients were observed. An inverse correlation was found between maximum SUV (SUVmax) and minimum ADC (ADCmin) (r = -0.583, p < 0.0001), and between tumor/brain ratio (T/Bratio) and ADCmin for all tumors (r = -0.532, p < 0.0001). Both SUVmax and T/Bratio in GBM were higher than LGG (p < 0.0001 and p < 0.0001), and those in PCNSL were also higher than GBM (p = 0.033 and p = 0.044). The ADCmin was lower in GBM (p = 0.011) and PCNSL (p = 0.01) than in LGG, while no significant difference was found between GBM and PCNSL (p = 0.90).

CONCLUSIONS

Tumor hypoxia assessed by (62)Cu-ATSM PET/CT correlated with microscopic diffusion capacity obtained by DWI in brain tumors. Both (62)Cu-ATSM PET/CT and DWI were considered feasible imaging methods for grading glioma. However, (62)Cu-ATSM PET/CT provided additional diagnostic information to differentiate between GBM and PCNSL.