Paper Info
Title
Weighted combination of multi-parametric MR imaging markers for evaluating radiation therapy related changes in the prostate
Abstract
Recently, multi-parametric (MP) Magnetic Resonance (MR) Imaging (T2-weighted, MR Spectroscopy (MRS), Diffusion-weighted (DWI)) has shown great potential for evaluating the early effects of radiotherapy (RT) in the prostate. In this work we present a framework for quantitatively combiningMP-MRImarkers in order to assess RT changes on a voxel-by-voxel basis. The suite of segmentation, registration, feature extraction, and classifier tools presented in this work will allow for identification of (a) residual disease, and (b) new foci of cancer (local recurrence) within the prostate. Our scheme involves, (a) simultaneously evaluating differences in pre-, post-RTMR imaging markers, and (b) intelligently integrating and weighting the imaging marker changes obtained in (a) to generate a combined MP-MRI difference map that can better quantify treatment specific changes in the prostate.We demonstrate the applicability of our scheme in studying intensity-modulated radiation therapy (IMRT)-related changes for a cohort of 14 MP (T2w, MRS, DWI) prostate MRI patient datasets. In the first step, the different MRI protocols from pre- and post-IMRT MRI scans are affinely registered (accounting for gland shrinkage), followed by automated segmentation of the prostate capsule using an active shape model. Individual imaging marker difference maps are generated by calculating the differences of textural, metabolic, and functional MRI marker attributes, pre- and post-RT, on a per-voxel basis. These difference maps are then combined via an intelligent optimization scheme to generate a combined weighted difference map, where higher difference values on the map signify larger change (new foci of cancer), and low difference values signify no/small change post-RT. In the absence of histological ground truth (surgical or biopsy), radiologist delineated CaP extent on pre-, and post-RT MRI was employed as the ground truth for evaluating the accuracy of our scheme in successfully identifying MP-MRI related disease changes post-RT. A mean area under the receiver operating curve (AUC) of 73.2% was obtained via the weighted MP-MRI map, when evaluated against expert delineated CaP extent on pre-, post-RT MRI. The difference maps corresponding to the individual structural (T2w intensities), functional (ADC intensities) and metabolic (choline, creatine) markers yielded a corresponding mean AUC of 54.4%, 68.6% and 70.8%.
Year
DOI
Venue
2011
10.1007/978-3-642-23944-1_9
Prostate Cancer Imaging
Keywords
Field
DocType
difference map,individual imaging marker difference,combined mp-mri difference map,low difference value,combined weighted difference map,radiation therapy,higher difference value,functional mri marker attribute,new focus,weighted combination,post-rt mri,different mri protocol,multi-parametric mr imaging marker
Nuclear medicine,Active shape model,Receiver operating characteristic,Focus (geometry),Segmentation,In vivo magnetic resonance spectroscopy,Radiation therapy,Prostate,Medicine,Magnetic resonance imaging
Conference
Volume
ISSN
Citations 
6963
0302-9743
5
PageRank 
References 
Authors
0.55
2
4
Name
Order
Citations
PageRank
Pallavi Tiwari111914.87
Satish Viswanath25710.67
John Kurhanewicz3818.45
Anant Madabhushi41736139.21