Yttrium-90 Radioembolization as a Possible New Treatment for Astrocytic Glioma: Histopathology and Comparison of PET/CT and MicroCT Dosimetry in Canine Models

Wednesday, March 8, 2023

4:12 PM – 4:21 PM

Location: Phoenix Convention Center, 224AB

Abstract Speaker(s)

Aryaman Gupta, n/a

Medical Student
Johns Hopkins University

Disclosure information not submitted.

Author/Co-author(s)

SM

Sasicha Manupipatpong, MD

Integrated Diagnostic and Interventional Radiology Resident
Johns Hopkins University
AP

Alexander Pasciak, PhD

Clinical Associate Professor of Radiology
University of Tennessee
FH

Ferdinand Hui, MD

Physician
Queens Medical Center
RK

Rebecca Krimins, DVM

Assistant Professor of Radiology and Radiological Science
Johns Hopkins University School of Medicine
LG

Larry Gainsburg, DVM

Neurologist
Mid-Atlantic Veterinary Neurology and Neurosurgery
DK

Dara Kraitchman, VMD, PhD

Professor of Radiology and Radiological Science
Johns Hopkins University
CW

Clifford Weiss, MD, FSIR, FCIRSE

Professor of Radiology and Biomedical Engineering
Johns Hopkins Univeristy School of Medicine

Disclosure(s):

Clifford Weiss, MD, FSIR, FCIRSE: Boston Scientific: Consultant (Ongoing), Intellectual Property Rights (Ongoing), Research Grant Recipient (Ongoing); Guerbet: Research Grant Recipient (Ongoing); Medtronic: Consultant (Ongoing), Research Grant Recipient (Ongoing); Siemens Healthineers: Consultant (Ongoing), Research Grant Recipient (Ongoing)

Purpose:

This study evaluated histopathology and compared the use of PET/CT and MicroCT dosimetry during yttrium-90 (⁹⁰Y) radioembolization (RE) in canine models with astrocytic gliomas.

Materials and Methods:

Five clinically stable patient dogs (P1-P5) with unilateral, intra-cranial brain masses >1cm in size underwent ipsilateral internal carotid artery RE with ⁹⁰Y glass microspheres (TheraSphere) 1-3 months after first seizure. Patient dogs received PET/CT 24-hours post-treatment, MRI at 1-, 3-, and 6-month intervals, and serial neurological exams by a veterinary neurologist. At time of natural death or euthanization, MicroCT dosimetry and histopathologic analyses were performed.

Results:

P5 had neurologic defects on presentation and a subsequent seizure 5 hours post-treatment leading to ventilatory arrest and expiration at 15 hours post-treatment. P1-P4 had a mean survival time of 565 days with mean time from treatment to return of seizure activity of 301 days. Post-treatment PET/CT reported an average dose to masses in P2-P4 of 46.9, 40.7, and 62.1 Gy while the dose to uninvolved brain tissue was 54.1, 33.9, and 57.3 Gy, respectively. Post-mortem MicroCT dosimetry demonstrated an average dose to masses in P2–P4 of 52.5, 48.2, and 68.1 Gy while the dose to uninvolved brain tissue was 28.2, 14.5, and 42.3 Gy, respectively. Follow-up MRI demonstrated decreased tumor size at 1 month (P1-P4) and 6mo (P1, P3, P4). Histopathology for P2-P5 confirmed the presence of high-grade astrocytic gliomas with rare mitotic figures and absence of glomeruloid vascularization.

Conclusion:

⁹⁰Y RE is feasible in the canine model, delivering 2-3x higher dose to mass compared to normal parenchyma based on microdosimetry. Patient dog mean survival time (565 days) was 9x that of medical symptom management alone (63 days – Moirano et al.). Compared to PET/CT, MicroCT reported higher ⁹⁰Y dose to tumors but lower dose to uninvolved cortex. Due to the small mass size, sphere concentration over time as the tumor shrank, and limited imaging resolution, PET/CT likely underestimated the tumor doses. Conversely, PET/CT has been shown to overestimate dose at low activity concentrations seen in normal brain tissue and thus reported higher doses in uninvolved cortex (Willowson et al.). MicroCT dosimetry is a more appropriate method to compare ⁹⁰Y RE dose delivery in canine brain masses.