The superior predictive value of 166Ho-scout compared with 99mTc-macroaggregated albumin prior to 166Ho-microspheres radioembolization in patients with liver metastases

Maarten L J Smits,Jip F Prince,Rutger C G Bruijnen,Arthur J A T Braat,Casper Beijst,Hugo W A M De Jong,Mathijs G Dassen,Marnix G E H Lam

doi:10.1007/s00259-019-04460-y

Maarten L J Smits, Jip F Prince + Show 6 more

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https://doi.org/10.1007/s00259-019-04460-y

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Abstract

PurposeAs an alternative to technetium-99m-macroaggregated albumin (99mTc-MAA), a scout dose of holmium-166 (166Ho) microspheres can be used prior to 166Ho-radioembolization. The use of identical particles for pre-treatment and treatment procedures may improve the predictive value of pre-treatment analysis of distribution. The aim of this study was to analyze the agreement between 166Ho-scout and 166Ho-therapeutic dose in comparison with the agreement between 99mTc-MAA and 166Ho-therapeutic dose.MethodsTwo separate scout dose procedures were performed (99mTc-MAA and 166Ho-scout) before treatment in 53 patients. First, qualitative assessment was performed by two blinded nuclear medicine physicians who visually rated the agreement between the 99mTc-MAA, 166Ho-scout, and 166Ho-therapeutic dose SPECT-scans (i.e., all performed in the same patient) on a 5-point scale. Second, agreement was measured quantitatively by delineating lesions and normal liver on FDG-PET/CT. These volumes of interest (VOIs) were co-registered to the SPECT/CT images. The predicted absorbed doses (based on 99mTc-MAA and 166Ho-scout) were compared with the actual absorbed dose on post-treatment SPECT.ResultsA total of 23 procedures (71 lesions, 22 patients) were included for analysis. In the qualitative analysis, 166Ho-scout was superior with a median score of 4 vs. 2.5 for 99mTc-MAA (p < 0.001). The quantitative analysis showed significantly narrower 95%-limits of agreement for 166Ho-scout in comparison with 99mTc-MAA when evaluating lesion absorbed dose (− 90.3 and 105.3 Gy vs. − 164.1 and 197.0 Gy, respectively). Evaluation of normal liver absorbed dose did not show difference in agreement between both scout doses and 166Ho-therapeutic dose (− 2.9 and 5.5 Gy vs − 3.6 and 4.1 Gy for 99mTc-MAA and 166Ho-scout, respectively).ConclusionsIn this study, 166Ho-scout was shown to have a superior predictive value for intrahepatic distribution in comparison with 99mTc-MAA.

Highlights

Based on the narrower width of the 95% limits of agreement and no overlap in confidence intervals of the 95% limits of agreement of the 99mTc-MAA (− 197.3 and − 130.8 Gy and 163.8 and 230.3 Gy) and 166Ho-scout (− 108.3 and − 72.3 Gy and 87.3 and 123.4 Gy) Bland-Altman plots, 166Ho scout performed significantly better than 99mTcMAA
This study showed that treatment planning prior to radioembolization can be improved by using a scout dose of 166Ho-microspheres instead of 99mTc-MAA
The qualitative and quantitative analysis showed that the agreement between 166Ho-scout and 166Ho-therapeutic dose was significantly superior to 99mTc-MAA

Summary

Introduction

This article is part of the Topical Collection on Oncology – Gastrointestinal. Treatment planning for radioembolization (known as Selective Internal Radiation Therapy or SIRT) of liver tumors is generally performed with technetium-99m macroaggregated albumin particles (99mTc-MAA). Aside from predicting the lung shunt and (other) non-target embolization, 99mTc-MAA is used to predict the activity distribution in the liver. Several studies have shown that the value of 99mTc-MAA to predict the distribution of 90Y in the liver is limited [1,2,3,4]

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