Y Wang1, S Tadimalla2, R Rai3, J Goodwin4, S Foster5, G Liney3, L Holloway3, A Haworth2. 1. Institute of Medical Physics, School of Physics, Faculty of Science, The University of Sydney, Sydney, NSW, Australia; Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia. Electronic address: ywan3672@uni.sydney.edu.au. 2. Institute of Medical Physics, School of Physics, Faculty of Science, The University of Sydney, Sydney, NSW, Australia. 3. Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia; Liverpool and Macarthur Cancer Therapy Centre, Liverpool Hospital, Liverpool, NSW, Australia; South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, Australia. 4. Department of Radiation Oncology, Calvary Mater Hospital, Waratah, NSW, Australia. 5. Discipline of Medical Imaging Science, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Radiology Department, Westmead Hospital, Westmead, NSW, Australia.
Abstract
INTRODUCTION: Quantitative MRI (qMRI) parameters have been increasingly used to develop predictive models to accurately monitor treatment response in prostate cancer after radiotherapy. To reliably detect changes in signal due to treatment response, predictive models require qMRI parameters with high repeatability and reproducibility. The purpose of this study was to measure qMRI parameter uncertainties in both commercial and in-house developed phantoms to guide the development of robust predictive models for monitoring treatment response. MATERIALS AND METHODS: ADC, T1, and R2* values were acquired across three 3 T scanners with a prostate-specific qMRI protocol using the NIST/ISMRM system phantom, RSNA/NIST diffusion phantom, and an in-house phantom. A B1 field map was acquired to correct for flip angle inhomogeneity in T1 maps. All sequences were repeated in each scan to assess within-session repeatability. Weekly scans were acquired on one scanner for three months with the in-house phantom. Between-session repeatability was measured with test-retest scans 6-months apart on all scanners with all phantoms. Accuracy, defined as percentage deviation from reference value for ADC and T1, was evaluated using the system and diffusion phantoms. Repeatability and reproducibility coefficients of variation (%CV) were calculated for all qMRI parameters on all phantoms. RESULTS: Overall, repeatability CV of ADC was <2.40%, reproducibility CV was <3.98%, and accuracy ranged between -8.0% to 2.7% across all scanners. Applying B1 correction on T1 measurements significantly improved the repeatability and reproducibility (p<0.05) but increased error in accuracy (p<0.001). Repeatability and reproducibility of R2* was <4.5% and <7.3% respectively in the system phantom across all scanners. CONCLUSION: Repeatability, reproducibility, and accuracy in qMRI parameters from a prostate-specific protocol was estimated using both commercial and in-house phantoms. Results from this work will be used to identify robust qMRI parameters for use in the development of predictive models to longitudinally monitor treatment response for prostate cancer in current and future clinical trials.
INTRODUCTION: Quantitative MRI (qMRI) parameters have been increasingly used to develop predictive models to accurately monitor treatment response in prostate cancer after radiotherapy. To reliably detect changes in signal due to treatment response, predictive models require qMRI parameters with high repeatability and reproducibility. The purpose of this study was to measure qMRI parameter uncertainties in both commercial and in-house developed phantoms to guide the development of robust predictive models for monitoring treatment response. MATERIALS AND METHODS: ADC, T1, and R2* values were acquired across three 3 T scanners with a prostate-specific qMRI protocol using the NIST/ISMRM system phantom, RSNA/NIST diffusion phantom, and an in-house phantom. A B1 field map was acquired to correct for flip angle inhomogeneity in T1 maps. All sequences were repeated in each scan to assess within-session repeatability. Weekly scans were acquired on one scanner for three months with the in-house phantom. Between-session repeatability was measured with test-retest scans 6-months apart on all scanners with all phantoms. Accuracy, defined as percentage deviation from reference value for ADC and T1, was evaluated using the system and diffusion phantoms. Repeatability and reproducibility coefficients of variation (%CV) were calculated for all qMRI parameters on all phantoms. RESULTS: Overall, repeatability CV of ADC was <2.40%, reproducibility CV was <3.98%, and accuracy ranged between -8.0% to 2.7% across all scanners. Applying B1 correction on T1 measurements significantly improved the repeatability and reproducibility (p<0.05) but increased error in accuracy (p<0.001). Repeatability and reproducibility of R2* was <4.5% and <7.3% respectively in the system phantom across all scanners. CONCLUSION: Repeatability, reproducibility, and accuracy in qMRI parameters from a prostate-specific protocol was estimated using both commercial and in-house phantoms. Results from this work will be used to identify robust qMRI parameters for use in the development of predictive models to longitudinally monitor treatment response for prostate cancer in current and future clinical trials.
Authors: Sirisha Tadimalla; Daniel J Wilson; David Shelley; Gavin Bainbridge; Margaret Saysell; Iosif A Mendichovszky; Martin J Graves; J Ashley Guthrie; John C Waterton; Geoffrey J M Parker; Steven P Sourbron Journal: J Magn Reson Imaging Date: 2022-02-27 Impact factor: 5.119
Authors: Madeline E Carr; Kathryn E Keenan; Robba Rai; Michael A Boss; Peter Metcalfe; Amy Walker; Lois Holloway Journal: Med Phys Date: 2022-04-11 Impact factor: 4.506