Added prognostic value of DCE blood volume imaging in patients with suspected recurrent or residual glioblastoma-A hybrid [¹⁸F]FET PET/MRI study

Background: Magnetic resonance imaging (MRI) cerebral blood volume (CBV) measurements improve the diagnosis of recurrent gliomas. The study investigated the prognostic value of dynamic contrast-enhanced (DCE) CBV imaging in treated IDH wildtype glioblastoma when added to MRI or amino acid positron emission tomography (PET).

Methods: Hybrid [¹⁸F]FET PET/MRI with 2CXM (2-compartment exchange model) DCE from 86 adult patients with suspected recurrent or residual glioblastoma were retrospectively analyzed. High CBV tumor volume (VOL_CBV), and contrast-enhancing (VOL_CE) and [¹⁸F]FET active tumor (VOL_FET) volumes were delineated. Absolute and fractional high CBV subvolumes within VOL_CE and VOL_FET were determined. Associations with overall survival (OS) were assessed by Cox analysis.

Results: Adjusted for methyltransferase gene status and steroid use all total tumor volumes were individually associated with shorter OS. Adding VOL_CBV to VOL_CE or VOL_FET only the effect of VOL_CBV was prognostic of OS (hazard ratio [HR] 1.327, P = .042 and 1.352, P = .011, respectively). High CBV subvolumes within both VOL_CE and VOL_FET were associated with shorter survival (HR 1.448, P = .042 and 1.416, P = .011, respectively), and the low CBV subvolumes with longer survival (HR 0.504, P = .002 and .365, P = .001, respectively). The fraction of VOL_CE and VOL_FET with high CBV was a strong predictor of OS with shorter median OS in upper versus lower tertiles (8.3 vs 14.5 months and 7.1 vs 15.6 months, respectively, both P < .001).

Conclusions: The high CBV tumor volume was a strong prognosticator of survival and allowed for the separation of high- and low-risk subvolumes underlining the heterogeneous physiological environment represented in the contrast-enhancing or metabolically active tumor volumes of treated glioblastoma.