publication

Fast technetium-99m liver SPECT for evaluation of the pre-treatment procedure for radioembolisation dosimetry

van der Velden, Sandra, Dietze, Martijn M A, Viergever, Max A, de Jong, Hugo W A M

DOI: https://doi.org/10.1002/mp.13253

Medical Physics 46 (1), p. 345-355

Abstract

PURPOSE: The efficiency of radioembolisation procedures could be greatly enhanced if results of the 99m Tc-MAA pre-treatment procedure were immediately available in the interventional suite, enabling one-day procedures as a result of direct estimation of the hepatic radiation dose and lung shunt fraction. This would, however, require a relatively fast, but still quantitative, SPECT procedure, which might be achieved with acquisition protocols using non-uniform durations of the projection images.

METHODS: SPECT liver images of the 150-MBq 99m Tc-MAA pre-treatment procedure were simulated for eight different lesion locations and two different lesion sizes using the digital XCAT phantom for both single- and dual-head scanning geometries with respective total acquisition times of 1, 2, 5, 10, and 30 minutes. Three non-uniform projection-time acquisition protocols ("half-circle SPECT (HCS)", "non-uniform SPECT (NUS) I" and "NUS II") for fast quantitative SPECT of the liver were designed and compared with the standard uniform projection-time protocol. Images were evaluated in terms of contrast-to-noise ratio (CNR), activity recovery coefficient (ARC), tumour/non-tumour (T/N) activity concentration ratio and lung shunt fraction (LSF) estimation. In addition, image quality was verified with a physical phantom experiment, reconstructed with both clinical and Monte Carlo-based reconstruction software.

RESULTS: Simulations showed no substantial change in image quality and dosimetry by usage of a non-uniform projection-time acquisition protocol. Upon shortening acquisition times, CNR dropped, but ARC, T/N ratio and LSF estimates were stable across all simulated acquisition times. Results of the physical phantom were in agreement with those of the simulations.

CONCLUSION: Both uniform and non-uniform projection-time acquisition liver SPECT protocols yield accurate dosimetric metrics for radioembolisation treatment planning in the interventional suite within 10 minutes, without compromising image quality. Consequently, fast quantitative SPECT of the liver in the interventional suite is feasible. This article is protected by copyright. All rights reserved.