Mariska P Luttje1, Laurens D van Buuren2, Peter R Luijten3, Marco van Vulpen3, Uulke A van der Heide2, Dennis W J Klomp3. 1. Imaging Division, University Medical Center, Utrecht, Netherlands. Electronic address: m.p.luttje@umcutrecht.nl. 2. Department of Radiotherapy, The Netherlands Cancer Institute - Antoni van Leeuwenhoek hospital, Amsterdam, Netherlands. 3. Imaging Division, University Medical Center, Utrecht, Netherlands.
Abstract
PURPOSE: Hypoxia is an important marker for resistance to therapy. In this study, we quantify the macroscopic effects of R2* mapping in prostate cancer patients incorporating susceptibility matching and field strengths effects. MATERIALS AND METHODS: 91 patients were scanned without endorectal coil (ERC) at 3T. Only when rectal gas was absent, data was included for analysis. Another group of 10 patients was scanned using a susceptibility matched ERC. To assess the residual contamination of R2 and macroscopic field non-uniformities, a group of 10 patients underwent ultra-high resolution 7T MRI. RESULTS: Of the patients scanned at 3T 60% presented rectal gas and were excluded, due to susceptibility artifacts. At 3T the tumor was significantly different (P<0.01) from the healthy surrounding tissue in R2* values at intrapatient level. Using the measured median R2* value of 24.9s-1 at 3T and 43.2s-1 at 7T of the peripheral zone, the minimum contribution of macroscopic susceptibility effects is 15% at 3T. CONCLUSION: R2* imaging might be a promising tool for hypoxia imaging, particularly when minimizing macroscopic susceptibility effects contaminating intrinsic R2* of tissue, such as rectal gas. At 3T macroscopic effects still contribute 15% in the R2* value, compared to ultra-high resolution R2* mapping at 7T.
PURPOSE:Hypoxia is an important marker for resistance to therapy. In this study, we quantify the macroscopic effects of R2* mapping in prostate cancerpatients incorporating susceptibility matching and field strengths effects. MATERIALS AND METHODS: 91 patients were scanned without endorectal coil (ERC) at 3T. Only when rectal gas was absent, data was included for analysis. Another group of 10 patients was scanned using a susceptibility matched ERC. To assess the residual contamination of R2 and macroscopic field non-uniformities, a group of 10 patients underwent ultra-high resolution 7T MRI. RESULTS: Of the patients scanned at 3T 60% presented rectal gas and were excluded, due to susceptibility artifacts. At 3T the tumor was significantly different (P<0.01) from the healthy surrounding tissue in R2* values at intrapatient level. Using the measured median R2* value of 24.9s-1 at 3T and 43.2s-1 at 7T of the peripheral zone, the minimum contribution of macroscopic susceptibility effects is 15% at 3T. CONCLUSION: R2* imaging might be a promising tool for hypoxia imaging, particularly when minimizing macroscopic susceptibility effects contaminating intrinsic R2* of tissue, such as rectal gas. At 3T macroscopic effects still contribute 15% in the R2* value, compared to ultra-high resolution R2* mapping at 7T.
Authors: Oliver J Gurney-Champion; Faisal Mahmood; Marcel van Schie; Robert Julian; Ben George; Marielle E P Philippens; Uulke A van der Heide; Daniela Thorwarth; Kathrine R Redalen Journal: Radiother Oncol Date: 2020-02-27 Impact factor: 6.280
Authors: Marcel A van Schie; Petra J van Houdt; Ghazaleh Ghobadi; Floris J Pos; Iris Walraven; Hans C J de Boer; Cornelis A T van den Berg; Robert Jan Smeenk; Linda G W Kerkmeijer; Uulke A van der Heide Journal: Front Oncol Date: 2019-12-04 Impact factor: 6.244