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Updated: Dec 25, 2025
Author Spotlight: Enhancing Diagnostic Strategies and Biomarker Development for Comprehensive Lung Function Analysis
Published on: August 9, 2024
Diffusion-weighted Imaging Voxelwise-matched Analyses of Lung Cancer at 3.0-T PET/MRI: Reverse Phase Encoding
Florent L Besson1, Brice Fernandez1, Sylvain Faure1
1From the Dept of Biophysics and Nuclear Medicine-Molecular Imaging, Hôpitaux Universitaires Paris-Saclay, Assistance Publique-Hôpitaux de Paris, CHU Bicêtre, 94270, Le Kremlin-Bicêtre, France (F.L.B., E.D.); Université Paris-Saclay, School of Medicine, Le Kremlin-Bicêtre, France (F.L.B., O.M., A.S., S.B., S.M., F.P., D. Montani, D. Mitiliian, E.F., V.L., E.D.), Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, 91401, France (F.L.B., C.C., V.L., E.D.); Applications and Workflow, GE Healthcare, Buc, France (B.F.); Laboratoire de Mathématiques d'Orsay, Université Paris-Saclay CNRS, 91405 Orsay, France (S.F.); Dept of Thoracic and Vascular Surgery and Heart-Lung Transplantation, Hôpital Marie Lannelongue, 92350 Le Plessis Robinson, France (O.M., S.M., D. Mitilian, E.F.); Dept of Respiratory and Intensive Care Medicine, Pulmonary Hypertension National Referral Center, Hôpitaux Universitaires Paris-Saclay, Assistance Publique-Hôpitaux de Paris, CHU Bicêtre, 94270, Le Kremlin-Bicêtre, France (A.S., X.M., S.B., F.P., D. Montani); Inserm UMR_S999 Pulmonary Hypertension: Pathophysiology and Novel Therapies, Hôpital Marie Lannelongue, 92350 Le Plessis Robinson, France (A.S., D. Montani); Service Hospitalier Frédéric Joliot (SHFJ), CEA/Université Paris-Saclay, Orsay, France (É.B., A.C., F.B., V.L.); Dept of Pathology, Hôpital Marie Lannelongue, 92350 Le Plessis Robinson, France (M.R.G.B.); NeuroSpin, CEA Saclay, Université Paris-Saclay, Gif-sur-Yvette, France and Parietal, INRIA, Palaiseau, 91120, France (H.C.).
Abstract:
Background PET/MRI has drawn increasing interest in thoracic oncology due to the simultaneous acquisition of PET and MRI data. Geometric distortions related to diffusion-weighted imaging (DWI) limit the evaluation of voxelwise multimodal analyses. Purpose To assess the effectiveness of reverse phase encoding in correcting DWI geometric distortion for multimodal PET/MRI voxelwise lung tumor analyses. Materials and Methods In this prospective study, reverse phase encoding method was implemented with 3.0-T PET/MRI to correct geometric distortions related to DWI. The method was validated in dedicated phantom and then applied to 12 consecutive patients (mean age, 66 years ± 13 [standard deviation]; 10 men) suspected of having lung cancer who underwent fluorodeoxyglucose PET/MRI between October 2018 and April 2019. The effects on DWI-related image matching and apparent diffusion coefficient (ADC) regional map computation were assessed. Consequences on multimodal PET/MRI voxelwise lung tumor analyses were evaluated. Spearman correlation coefficients (rs) between the standardized uptake value (SUV) and ADC data corrected for distortion were computed from optimal realigned DWI PET data, along with bootstrap confidence intervals. Results Phantom results showed that in highly distorted areas, correcting the distortion significantly reduced the mean error against the ground truth (-25% ± 10.6 to -18.4% ± 12.6; P < .001) and the number of voxels with more than 20% error (from 85.3% to 31.4%). In the 12 patients, the coregistration of multimodal PET/MRI tumor data was improved by using the reverse phase encoding method (0.4%-44%). In all tumors, voxelwise correlations (rs) between ADC and SUV revealed null or weak monotonic relationships (mean rs of 0.016 ± 0.24 with none above 0.5). Conclusion Reverse phase encoding is a simple-to-implement method for improved diffusion-weighted multimodal PET/MRI voxelwise-matched analyses in lung cancer. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Colletti in this issue.
Insights
Reverse phase encoding effectively corrects geometric distortions in diffusion-weighted imaging for PET/MRI lung cancer analysis. This improves multimodal image matching and voxelwise analysis accuracy.
Area of Science:
- Medical Imaging
- Oncology
- Radiology
Background:
- Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI) is increasingly used in thoracic oncology.
- Geometric distortions in diffusion-weighted imaging (DWI) hinder accurate voxelwise multimodal analyses.
- Accurate image registration is crucial for combining PET and MRI data in lung cancer studies.
Purpose of the Study:
- To evaluate the efficacy of reverse phase encoding in correcting DWI geometric distortion.
- To improve voxelwise multimodal analyses for lung tumors using PET/MRI.
- To assess the impact of distortion correction on apparent diffusion coefficient (ADC) and standardized uptake value (SUV) correlations.
Main Methods:
- Prospective study using 3.0-T PET/MRI with reverse phase encoding for DWI distortion correction.
- Validation in phantom studies followed by application in 12 lung cancer patients.
- Assessment of coregistration accuracy and computation of voxelwise correlations between ADC and SUV.
Main Results:
- Phantom validation demonstrated significant reduction in geometric distortion errors.
- Reverse phase encoding improved multimodal PET/MRI tumor data coregistration by 0.4%-44% in patients.
- Voxelwise correlations between ADC and SUV in tumors were weak (mean r_s = 0.016 ± 0.24).
Conclusions:
- Reverse phase encoding is a practical method to enhance DWI accuracy in multimodal PET/MRI.
- This technique improves voxelwise analysis for lung cancer detection and characterization.
- The study provides a method for more reliable quantitative analysis in thoracic oncology.
