[Ga68] DOTATATE PET/MRI-guided radiosurgical treatment planning and response assessment in meningiomas

Abstract

Background: Our purpose was to determine the utility of [68Ga]-DOTATATE PET/MRI in meningioma response assessment following radiosurgery.

Methods: Patients with meningioma prospectively underwent postoperative DOTATATE PET/MRI. Co-registered PET and gadolinium-enhanced T1-weighted MRI were employed for radiosurgery planning. Follow-up DOTATATE PET/MRI was performed at 6-12 months post-radiosurgery. Maximum absolute standardized uptake value (SUV) and SUV ratio (SUVRSSS) referencing superior sagittal sinus (SSS) blood pool were obtained. Size change was determined by Response Assessment in Neuro-Oncology (RANO) criteria. Association of SUVRSSS change magnitude and progression-free survival (PFS) was evaluated using Cox regression.

Results: Twenty-seven patients with 64 tumors (26% World Health Organization [WHO]-1, 41% WHO-2, 26% WHO-3, and 7% WHO-unknown) were prospectively followed post stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT; mean dose: 30 Gy, modal dose 35 Gy, mean of 5 fractions). Post-irradiation SUV and SUVRSSS decreased by 37.4% and 44.4%, respectively (P < .0001). Size product decreased by 8.9%, thus failing to reach the 25% significance threshold as determined by RANO guidelines. Mean follow-up time was 26 months (range: 6-44). Overall mean PFS was 83% and 100%/100%/54% in WHO-1/-2/-3 subcohorts, respectively, at 34 months. At maximum follow-up (42-44 months), PFS was 100%/83%/54% in WHO-1/-2/-3 subcohorts, respectively. Cox regression analyses revealed a hazard ratio of 0.48 for 10-unit reduction in SUVRSSS in the SRS cohort.

Conclusions: DOTATATE PET SUV and SUVRSSS demonstrated marked, significant decrease post-radiosurgery. Lesion size decrease was statistically significant; however, it was not clinically significant by RANO criteria. DOTATATE PET/MR thus represents a promising imaging biomarker for response assessment in meningiomas treated with radiosurgery.

Clinicaltrials.gov identifier: NCT04081701.

Keywords: DOTATATE; PET/MRI; meningioma; outcomes; radiosurgery.

Figure 1.

DOTATATE PET-derived standardized uptake value (SUV) and SUVRsss decrease post-RT stratified by World Health Organization (WHO) grade. Figures A–C describe the SUV changes post-RT of the WHO grade subcohorts from baseline. Similarly, figures D–F describe the SUVRsss changes. Asterisks (*) indicate P-values referencing paired non-parametric t-test results for the respective pre- and post-RT data. ** indicates P-value < .01, *** indicates P-value < .001, and **** indicates P-value < .0001.

Figure 2.

DOTATATE-PET derived standardized uptake value and SUVR_SSS decrease post-radiation therapy (RT; A and B, respectively), as well as MRI-derived size product decrease post-RT (C) are visualized. Asterisks (*) indicate P-values referencing paired non-parametric t-test results for the respective pre- and post-RT data. **** indicates P-value < .0001. *** indicates P-value of .003.

Figure 3.

Kaplan–Meier Survival Analyses of the total cohort (A) and stratified by World Health Organization (WHO) grade (B). Total progression-free survival (PFS) was 100% at 0–11 months; 95% at 13–15 months; 90% at 16–25 months; 83% at 29–33 months; 75% at 37–44 months. PFS was 100% at 0–42 months for WHO grade 1; PFS was 100% at 0–33 months and 83% at 34–42 months for WHO grade 2; PFS was 100% at 0–13 months, 86% at 14–15 months, 71% at 16–24 months, and 54% at 25–44 months for WHO grade 3.

Figure 4.

A 67-year-old woman with postoperative residual atypical meningioma visualized on MRI as 2 enhancing dural-based nodules (A), better delineated as intensely DOTATATE avid lesions on PET/MRI (B), underwent PET/MRI-guided SBRT (30 Gy in 5 fractions). The lesions pre-SBRT had standardized uptake value (SUV) of up to 14.7, with SUVR_SSS of up to 12.3 (C). Follow-up MRI 7 months post-SBRT demonstrates no significant change in lesion size (B) Post-SBRT PET/MRI demonstrated markedly decreased SUV and SUVR_SSS of 6.3 and 5.7, respectively (D). Color scale (PET MRI, shown in C and D): SUV 0–15.