Partition Model–Based ^99mTc-MAA SPECT/CT Predictive Dosimetry Compared with ⁹⁰Y TOF PET/CT Posttreatment Dosimetry in Radioembolization of Hepatocellular Carcinoma: A Quantitative Agreement Comparison

Abstract

90 Y-microsphere selective internal radiation therapy (SIRT) is a valuable treatment in unresectable hepatocellular carcinoma (HCC). Partition-model predictive dosimetry relies on differential tumor-to-nontumor perfusion evaluated on pretreatment 99m Tcmacroaggregated albumin (MAA) SPECT/CT. The aim of this study was to evaluate agreement between the predictive dosimetry of in tumor volumes (TVs) and nontumor volumes (NTVs) for glass and resin spheres. The Lin concordance (r c ) was used to measure accuracy (C b ) and precision (r). Results: Administered activity ranged from 0.8 to 1.9 GBq for glass spheres and from 0.6 to 3.4 GBq for resin spheres, and the respective TVs ranged from 2 to 125 mL and from 6 to 1,828 mL. The mean dose D In selective internal radiation therapy (SIRT), 90 Y-microsphere radioembolization is a valuable therapeutic option in patients presenting with unresectable hepatocellular carcinoma (HCC) not eligible for other therapeutic options (1-3).SIRT with 90 Y-charged microspheres relies on differential vascularization between tumor and nontumor liver parenchyma, resulting in favorable, potentially tumoricidal, deposition of microsphere activity in tumors while minimizing absorbed dose to the functional parenchyma, thus preventing toxicity. Two microsphere types are clinically available: resin spheres (SIR spheres; SirTex Medical Ltd.) and glass spheres (TheraSphere; Nordion Inc.). Despite being of similar size (;30 mm), these two types of sphere differ in specific activity, density (ffi 4 · 10 5 glass spheres/GBq; ffi 2 · 10 7 resin spheres/GBq), and injection solution (NaCl for glass spheres; water for resin spheres), leading to potential differences in embolic effect and local variations in the radiation dose deposited in tissues.Predictive dosimetry has included hepatic CT angiography for catheter positioning and partition modeling based on 99m Tcmacroaggregate albumin (MAA) SPECT/CT acquisition (4,5).The manufacturer-recommended activity for resin spheres is based on a semiempiric formula including body surface area (6,7) and tumor burden. This approach can be refined using a 3-compartment partition model (4) including the lungs, liver TVs, and liver NTVs derived from a pretreatment 99m Tc-MAA SPECT/CT scan. The prescribed glass sphere activity is based on a 2-compartment model (lungs and targeted liver regions) aiming to deliver a dose of 80-150 Gy to the targeted liver volume.90 Y time-of-flight (TOF) PET/CT dosimetry (8) provides a valuable tool to verify 99m Tc-MAA SPECT/CT-based predictive dosimetry.

90Y glass microspheres radionuclide therapy: robustness analysis with a dosimetry software

“…When the distributions disagree, PLANET ® Onco provides a quantitative value of the delivered TV dose; this information is strictly missing in the standard approach. Namely, predictive dosimetry was found giving a higher mean TV dose by a factor 1.44 ± 0.34; a similar finding of Gnesin et al [3]. Such under-dosage to TV could yield a procedure failure.…”

The conflict between treatment optimization and registration of radiopharmaceuticals with fixed activity posology in oncological nuclear medicine therapy

“…Stem cell autologous transplantation is included in this study. A third example is the recently reported radioembolization of hepatocarcinoma with 90 Y glass microspheres [12], for which a treatment-planning paradigm was developed that aimed mainly to deliver the MTAD to the liver parenchyma, since the prediction of tumour absorbed dose can be uncertain [13].…”

Resin Versus Glass Microspheres for 90Y Transarterial Radioembolization: Comparing Survival in Unresectable Hepatocellular Carcinoma Using Pretreatment Partition Model Dosimetry

“…The TV was assessed on SPECT/CT with morphologic information from any available imaging modalities (enhanced CT, MR, or 18 F-FDG PET/CT) when needed. The TV estimated from the 99m Tc-MAA SPECT/CT was used to determine the activity of 90 Y microspheres to administer using our recently published PMD for TARE (14). Patients with small-tumor volumes were preferentially addressed to 90 Y glass microspheres because of their higher specific 90 Y activity and lower particle number aiming at avoiding lesion saturation and consecutive reflux to nontarget volumes.…”

“…To the best of our knowledge, only a recent retrospective review (13) has compared the outcome of both types of 90 Y microspheres in patients with unresectable HCC (uHCC), concluding in a survival benefit for glass microspheres. The aim of the current study was to compare progression-free survival (PFS) and OS between 2 groups of patients treated with 90 Y resin and glass microspheres for uHCC using pretreatment PMD (14). Second, we compared PFS and OS of each type of 90 Y microsphere according to early/intermediate (combining BCLC A and B) stages and the advanced (BCLC C) stage, which is associated with a poor prognosis.…”