Evaluation of diffusion models in breast cancer. Issue 8 (27th July 2015)

• Record Type: Journal Article
• Authors: Panek, Rafal; Borri, Marco; Orton, Matthew; O'Flynn, Elizabeth; Morgan, Veronica; Giles, Sharon L.; deSouza, Nandita; Leach, Martin O.; Schmidt, Maria A.
• Is Part Of: Medical physics. Volume 42:Issue 8(2015)Part 1
• Page Start: 4833
• Page End: 4839
• Publication Date: 2015-07-27
• Subjects: Bayes methods -- biodiffusion -- biomedical MRI -- blood vessels -- cancer -- data acquisition -- data analysis -- distortion -- eddy currents -- feature extraction -- feature selection -- image sequences -- information theory -- mammography -- medical image processing -- phantoms -- physiological models -- tumours; Magnetic resonance imaging -- Image analysis -- Cancer -- Information and communication theory; Involving electronic [emr] or nuclear [nmr] magnetic resonance, e.g. magnetic resonance imaging -- Biological material, e.g. blood, urine; Haemocytometers -- Methods or arrangements for processing data by operating upon the order or content of the data handled -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general; diffusion weighted MR imaging -- diffusion models -- breast cancer; Diffusion -- Cancer -- Computer modeling -- Eddies -- Encoding -- Medical image distortion -- Biomedical modeling -- Sequence analysis -- Medical magnetic resonance imaging; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4927255
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: The purpose of this study is to investigate whether the microvascular pseudodiffusion effects resulting with non‐monoexponential behavior are present in breast cancer, taking into account tumor spatial heterogeneity. Additionally, methodological factors affecting the signal in low and high diffusion‐sensitizing gradient ranges were explored in phantom studies. Methods: The effect of eddy currents and accuracy of b ‐value determination using a multiple b ‐value diffusion‐weighted MR imaging sequence were investigated in test objects. Diffusion model selection and noise were then investigated in volunteers ( n = 5) and breast tumor patients ( n = 21) using the Bayesian information criterion. Results: 54.3% of lesion voxels were best fitted by a monoexponential, 26.2% by a stretched‐exponential, and 19.5% by a biexponential intravoxel incoherent motion (IVIM) model. High correlation (0.92) was observed between diffusion coefficients calculated using mono‐ and stretched‐exponential models and moderate (0.59) between monoexponential and IVIM (medians: 0.96/0.84/0.72 × 10 −3 mm 2 /s, respectively). Distortion due to eddy currents depended on the direction of the diffusion gradient and displacement varied between 1 and 6 mm for high b ‐value images. Shift in the apparent diffusion coefficient due to intrinsic field gradients was compensated for by averaging diffusion data obtained from opposite directions. Conclusions: Pseudodiffusion and intravoxel heterogeneity effects were not observed in approximately half of breast cancer and normal tissue voxels. This result indicates that stretched and IVIM models should be utilized in regional analysis rather than global tumor assessment. Cross terms between diffusion‐sensitization gradients and other imaging or susceptibility‐related gradients are relevant in clinical protocols, supporting the use of geometric averaging of diffusion‐weighted images acquired with diffusion‐sensitization gradients in opposite directions.