1
|
Sakai NS, Bray TJP, Taylor SA. Quantitative Magnetic Resonance Imaging (qMRI) of the Small Bowel in Crohn's Disease: State-of-the-Art and Future Directions. J Magn Reson Imaging 2024. [PMID: 38970359 DOI: 10.1002/jmri.29511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 05/07/2024] [Accepted: 05/10/2024] [Indexed: 07/08/2024] Open
Abstract
Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal tract in which repeated episodes of acute inflammation may lead to long-term bowel damage. Cross-sectional imaging is used in conjunction with endoscopy to diagnose and monitor disease and detect complications. Magnetic resonance imaging (MRI) has demonstrable utility in evaluating inflammatory activity. However, subjective interpretation of conventional MR sequences is limited in its ability to fully phenotype the underlying histopathological processes in chronic disease. In particular, conventional MRI can be confounded by the presence of mural fibrosis and muscle hypertrophy, which can mask or sometimes mimic inflammation. Quantitative MRI (qMRI) methods provide a means to better differentiate mural inflammation from fibrosis and improve quantification of these processes. qMRI may also provide more objective measures of disease activity and enable better tailoring of treatment. Here, we review quantitative MRI methods for imaging the small bowel in CD and consider the path to their clinical translation. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.
Collapse
Affiliation(s)
- Naomi S Sakai
- Centre for Medical Imaging, University College London, London, UK
| | - Timothy J P Bray
- Centre for Medical Imaging, University College London, London, UK
| | - Stuart A Taylor
- Centre for Medical Imaging, University College London, London, UK
| |
Collapse
|
2
|
Mao L, Li Y, Cui B, Lu L, Dou W, Pylypenko D, Zhu J, Li H. Multiparametric MRI for Staging of Bowel Inflammatory Activity in Crohn's Disease with MUSE-IVIM and DCE-MRI: A Preliminary Study. Acad Radiol 2024; 31:880-888. [PMID: 37730492 DOI: 10.1016/j.acra.2023.08.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 08/20/2023] [Accepted: 08/23/2023] [Indexed: 09/22/2023]
Abstract
RATIONALE AND OBJECTIVES To investigate if the combination of multishot diffusion imaging-based multiplexed sensitivity encoding intravoxel incoherent motion (MUSE-IVIM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is feasible for staging Crohn's disease (CD) activity. MATERIALS AND METHODS A total of 65 CD patients were enrolled and analyzed in this retrospective study. The simplified endoscopic score for Crohn's disease (SES-CD) and magnetic resonance index of activity (MaRIA) were used as the reference. The MUSE-IVIM and DCE-MRI data were acquired at 3.0-T MRI scanner and processed by two radiologists. Three MUSE-IVIM parameters: fast apparent diffusion coefficient (ADCfast), slow apparent diffusion coefficient (ADCslow), and the fractional perfusion (Fraction of ADCfast), as well as four DCE-MRI parameters: volume transfer constant (Ktrans), rate constant (Kep), extravascular extracellular volume fraction (Ve), and plasma volume fraction (Vp) were generated. Intraclass correlation coefficient (ICC), non-parametric test (Kruskal-Wallis H and Mann-Whitney U), logistic regression, receiver operating characteristic analysis, Delong test, and Spearman's correlation test were performed. RESULTS According to SES-CD, 116 ileocolonic segments with CD lesions were identified as: inactive, mild, and moderate to severe. With multivariable logistic regression analysis, ADCfast (p < 0.001), Fraction of ADCfast (p = 0.005), Ktrans (p < 0.001) and Kep (p = 0.003) were identified as significant factors for differentiating among the three groups. Binary logistic analyses identified ADCfast (p = 0.001), Ktrans (p = 0.014), and Kep (p = 0.029) as independent predictors for the active status. The combination of ADCfast, Ktrans, and Kep performed better than MaRIA score (p = 0.028), for differentiating inactive and active status. MaRIA score was positively correlated with ADCfast (p < 0.001), Ktrans (p < 0.001), Kep (p < 0.001), and Ve (p = 0.001), however, negatively correlated with Fraction of ADCfast (p < 0.001). CONCLUSION The combination of MUSE-IVIM and DCE-MRI has been demonstrated to accurately stage inflammatory activity in CD.
Collapse
Affiliation(s)
- Liangqiang Mao
- Department of Radiology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, PR China
| | - Yan Li
- Department of Radiology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, PR China
| | - Bota Cui
- Department of Gastroenterology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, PR China
| | - Lin Lu
- Department of Radiology, Columbia University Medical Center, New York, New York
| | - Weiqiang Dou
- GE Healthcare, MR Research China, Beijing, PR China
| | | | - Jianguo Zhu
- Department of Radiology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, PR China.
| | - Haige Li
- Department of Radiology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, PR China
| |
Collapse
|
3
|
Sun P, Zhu D, Li J, Zhang J, Zeng M, Fang L, Ruan J, Zhao X, Shi Y, Wang S, Zhao B. Intravoxel incoherent motion diffusion-weighted imaging in quantitative evaluation of Ileal Crohn's disease - A comparison with dynamic contrast-enhanced magnetic resonance imaging and ileocolonoscopy. Magn Reson Imaging 2023; 97:82-90. [PMID: 36608907 DOI: 10.1016/j.mri.2022.12.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 12/30/2022] [Accepted: 12/31/2022] [Indexed: 01/04/2023]
Abstract
OBJECTIVES To investigate the prospective role of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in evaluating terminal ileal Crohn's disease (CD) inflammation quantitatively, compared with quantitative dynamic contrastenhanced magnetic resonance imaging (DCE-MRI) and ileocolonoscopic segmental score. METHODS Fifty CD patients underwent magnetic resonance enterography (MRE) including IVIM-DWI and quantitative DCE-MRI from Jan. 2017 to Nov. 2019. ADC, D, D* and f value of IVIM-DWI and Ktrans, Kep, and Ve value of DCE-MRI in normal (n = 50) and inflamed bowel segments (n = 50), defined during the clinical MRI analysis, were calculated and compared using Wilcoxon signed-rank tests respectively. Receiver operating characteristic (ROC) analysis was performed. Correlations between IVIM-DWI and DCE-MRI parameters in comparison with ileocolonoscopic segmental score were assessed using Spearman's rank correlation analysis. RESULTS For IVIM-DWI, ADC, D, D* and f value showed significant differences respectively between normal and inflamed bowel segments (p < 0.05). ADC value presented the highest diagnostic accuracy (AUC = 0.813) and sensitivity (92%), and D value presented the highest specificity (84%) for the evaluation of inflamed bowel segments. For DCE-MRI, Ktrans value presented the highest diagnostic accuracy (AUC = 0.835), the highest sensitivity for Kep value (88%) and the highest specificity for Ve value (96%). ADC, f and Ktrans value had high correlations with ileocolonoscopic score respectively (r = -0.739-0.876, p < 0.01). The logarithm of normalized signal intensity/b-values for IVIM-DWI could also indicate directly the evident difference between the normal and inflamed bowel segments of terminal ileal CD. CONCLUSION IVIM-DWI will be another promising noninvasive tool to provide precise quantitative-indicators in evaluating inflamed bowel segments of terminal ileal CD with little contrast-agent damage worries.
Collapse
Affiliation(s)
- Peiwen Sun
- Department of Radiology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China
| | - Diru Zhu
- Department of Radiology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China
| | - Junheng Li
- Department of Radiology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China
| | - Jilei Zhang
- Shanghai MicroPort MedBot, Shanghai 201210, China
| | - Meiying Zeng
- Department of Radiology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China
| | - Leilei Fang
- Department of Gastroenterology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China
| | - Jianping Ruan
- Department of Radiology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China
| | - Xiance Zhao
- Clinical Science, Philips Healthcare, Shanghai 200040, PR China
| | - Yanhong Shi
- Department of Gastroenterology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China
| | - Shuai Wang
- Department of Radiology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China
| | - Binghui Zhao
- Department of Radiology, Shanghai Tenth People's Hospital of Tongji University Medical School, Shanghai 200072, China.
| |
Collapse
|
4
|
Cicero G, Alibrandi A, Blandino A, Ascenti V, Fries W, Viola A, Mazziotti S. DWI ratios: New indexes for Crohn's disease activity at magnetic resonance enterography? LA RADIOLOGIA MEDICA 2023; 128:16-26. [PMID: 36583843 DOI: 10.1007/s11547-022-01573-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 12/05/2022] [Indexed: 12/31/2022]
Abstract
BACKGROUND The aim of the study was to provide radiologists and clinicians a rapid tool for assessment of intestinal inflammation in Crohn's disease (CD) patients through quantification of diffusion-weighted imaging (DWI) signal intensity while performing magnetic resonance enterography (MRE). MATERIALS AND METHODS A monocentric retrospective study was conducted between September 2018 and July 2021 on CD patients who underwent MRE. Two radiologists measured signal intensity on DWI scans at the highest b-value (800 s/mm2) within pathologic intestinal walls, lymph nodes, spleen and psoas muscle and calculated the relative ratios. Spearman, Mann-Whitney and Jonckheere-Terpstra tests were applied for estimating correlation among ratios, significant differences between the two patient groups and determining the trend in relation to endoscopic classes. Wilcoxon's and Cronbach's alpha tests were employed for comparison of DWI measurements and ratios between the two observers. RESULTS Fifty-nine patients were enrolled in the study. In the non-surgical group, correlation has been found among Simple Endoscopic Score for Crohn's Disease (SES-CD) classes and the different ratios: bowel/spleen (p = 0.034), bowel/psoas (p = 0.008) and bowel/lymph node (p = 0.010). Within the surgical group, positive correlation was found only between bowel/lymph node ratio and bowel/psoas ratio (p = 0.014). The J-T test demonstrated an increasing monotonic trend for bowel/psoas ratio and bowel/lymph node ratio and SES-CD classes. Inter-reader evaluation demonstrated no statistical differences for DWI measurements and high degree of concordance for the final ratios. CONCLUSION DWI ratios correlate with endoscopic classes in non-surgical patients and have inter-observer reproducibility.
Collapse
Affiliation(s)
- Giuseppe Cicero
- Department of Biomedical Sciences and Morphological and Functional Imaging, University of Messina, Policlinico "G. Martino" Via Consolare Valeria 1, 98100, Messina, Italy.
| | - Angela Alibrandi
- Division of Statistical and Mathematical Sciences, Department of Economics, University of Messina, Messina, Italy
| | - Alfredo Blandino
- Department of Biomedical Sciences and Morphological and Functional Imaging, University of Messina, Policlinico "G. Martino" Via Consolare Valeria 1, 98100, Messina, Italy
| | - Velio Ascenti
- Diagnostic and Interventional Radiology Unit, University of Milan, Milan, Italy
| | - Walter Fries
- Inflammatory Bowel Disease Unit, A.O.U. Policlinico "G. Martino", Messina, Italy
| | - Anna Viola
- Inflammatory Bowel Disease Unit, A.O.U. Policlinico "G. Martino", Messina, Italy
| | - Silvio Mazziotti
- Department of Biomedical Sciences and Morphological and Functional Imaging, University of Messina, Policlinico "G. Martino" Via Consolare Valeria 1, 98100, Messina, Italy
| |
Collapse
|
5
|
Exploring arterial tissue microstructural organization using non-Gaussian diffusion magnetic resonance schemes. Sci Rep 2021; 11:22247. [PMID: 34782651 PMCID: PMC8593063 DOI: 10.1038/s41598-021-01476-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 10/13/2021] [Indexed: 12/02/2022] Open
Abstract
The purpose of this study was to characterize the alterations in microstructural organization of arterial tissue using higher-order diffusion magnetic resonance schemes. Three porcine carotid artery models namely; native, collagenase treated and decellularized, were used to estimate the contribution of collagen and smooth muscle cells (SMC) on diffusion signal attenuation using gaussian and non-gaussian schemes. The samples were imaged in a 7 T preclinical scanner. High spatial and angular resolution diffusion weighted images (DWIs) were acquired using two multi-shell (max b-value = 3000 s/mm2) acquisition protocols. The processed DWIs were fitted using monoexponential, stretched-exponential, kurtosis and bi-exponential schemes. Directionally variant and invariant microstructural parametric maps of the three artery models were obtained from the diffusion schemes. The parametric maps were used to assess the sensitivity of each diffusion scheme to collagen and SMC composition in arterial microstructural environment. The inter-model comparison showed significant differences across the considered models. The bi-exponential scheme based slow diffusion compartment (Ds) was highest in the absence of collagen, compared to native and decellularized microenvironments. In intra-model comparison, kurtosis along the radial direction was the highest. Overall, the results of this study demonstrate the efficacy of higher order dMRI schemes in mapping constituent specific alterations in arterial microstructure.
Collapse
|
6
|
Alyami AS, Williams HG, Argyriou K, Gunn D, Wilkinson-Smith V, White JR, Alyami J, Gowland PA, Moran GW, Hoad CL. Test-retest assessment of non-contrast MRI sequences to characterise and quantify the small bowel wall in healthy participants. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2021; 34:791-804. [PMID: 34089407 PMCID: PMC8578109 DOI: 10.1007/s10334-021-00931-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/10/2021] [Accepted: 05/18/2021] [Indexed: 11/08/2022]
Abstract
Objective Quantitative Magnetic Resonance Imaging sequences have been investigated as objective imaging biomarkers of fibrosis and inflammation in Crohn’s disease. Aim To determine the repeatability and inter- and intra-observer agreement of these measures in the prepared small bowel wall. Methods Ten healthy participants were scanned at 3 T on 2 separate occasions using T1 and T2 relaxometry, IVIM-DWI and MT sequences. Test–retest repeatability was assessed using the coefficient of variation (CoV) and intra-class correlation coefficients (ICCs) were used to evaluate the intra- and inter-observer agreement Results Test–retest repeatability in the bowel wall was excellent for apparent diffusion coefficient (ADC), magnetisation transfer ratio (MTR), T1, and diffusion coefficient D (CoV 5%, 7%, 8%, and 10%, respectively), good for perfusion fraction (PF) (CoV 20%) and acceptable for T2 (CoV 21%). Inter-observer agreement was good for the T2, D and ADC (ICC = 0.89, 0.86, 0.76, respectively) and moderate for T1 (ICC = 0.55). Intra-observer agreement was similar to inter-observer agreement. Discussion This study showed variable results between the different parameters measured. Test–retest repeatability was at least acceptable for all parameters except pseudo-diffusion coefficient D*. Good inter- and intra-observer agreement was obtained for T2, ADC and D, with these parameters performing best in this technical validation study.
Collapse
Affiliation(s)
- Ali S Alyami
- Faculty of Applied Medical Sciences, Diagnostic Radiology, Jazan University, Jazan, Saudi Arabia.,School of Medicine, University of Nottingham, Nottingham, UK.,Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Hannah G Williams
- School of Medicine, University of Nottingham, Nottingham, UK.,Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Konstantinos Argyriou
- National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - David Gunn
- School of Medicine, University of Nottingham, Nottingham, UK.,National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - Victoria Wilkinson-Smith
- School of Medicine, University of Nottingham, Nottingham, UK.,National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - Jonathan R White
- School of Medicine, University of Nottingham, Nottingham, UK.,National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - Jaber Alyami
- Diagnostic Radiology Department, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Penny A Gowland
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK.,National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - Gordon W Moran
- School of Medicine, University of Nottingham, Nottingham, UK.,National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - Caroline L Hoad
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK. .,National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK.
| |
Collapse
|
7
|
Abstract
ABSTRACT In this review article, we present the latest developments in quantitative imaging biomarkers based on magnetic resonance imaging (MRI), applied to the diagnosis, assessment of response to therapy, and assessment of prognosis of Crohn disease. We also discuss the biomarkers' limitations and future prospects. We performed a literature search of clinical and translational research in Crohn disease using diffusion-weighted MRI (DWI-MRI), dynamic contrast-enhanced MRI (DCE-MRI), motility MRI, and magnetization transfer MRI, as well as emerging topics such as T1 mapping, radiomics, and artificial intelligence. These techniques are integrated in and combined with qualitative image assessment of magnetic resonance enterography (MRE) examinations. Quantitative MRI biomarkers add value to MRE qualitative assessment, achieving substantial diagnostic performance (area under receiver-operating curve = 0.8-0.95). The studies reviewed show that the combination of multiple MRI sequences in a multiparametric quantitative fashion provides rich information that may help for better diagnosis, assessment of severity, prognostication, and assessment of response to biological treatment. However, the addition of quantitative sequences to MRE examinations has potential drawbacks, including increased scan time and the need for further validation before being used in therapeutic drug trials as well as the clinic.
Collapse
|
8
|
Greer MLC, Cytter-Kuint R, Pratt LT, Soboleski D, Focht G, Castro DA. Clinical-stage Approaches for Imaging Chronic Inflammation and Fibrosis in Crohn's Disease. Inflamm Bowel Dis 2020; 26:1509-1523. [PMID: 32946578 DOI: 10.1093/ibd/izaa218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Indexed: 02/06/2023]
Abstract
The number of imaging-based indices developed for inflammatory bowel disease as research tools, objectively measuring ileocolonic and perianal activity and treatment response, has expanded in the past 2 decades. Created primarily to assess Crohn's disease (CD), there is increasing adoption of these indices into the clinical realm to guide patient care. This translation has been facilitated by validation in adult and pediatric populations, prompted by simplification of score calculations needed for practical application outside the research environment. The majority of these indices utilize magnetic resonance imaging (MRI), specifically MR enterography (MRE) and pelvic MRI, and more recently ultrasound. This review explores validated indices by modality, anatomic site and indication, including for documentation of the presence and extent of CD, disease progression, complications, and treatment response, highlighting those in clinical use or with the potential to be. As well, it details index imaging features used to quantify chronic inflammatory activity, severity, and to lesser extent fibrosis, in addition to their reference standards and any modifications. Validation in the pediatric population of indices primarily developed in adult cohorts such as the Magnetic Resonance Index of Activity (MaRIA), the Simplified Magnetic Resonance Index of Activity (MARIAs), and the MRE global score (MEGS), together with newly developed pediatric-specific indices, are discussed. Indices that may be predictive of disease course and investigational techniques with the potential to provide future imaging biomarkers, such as multiparametric MRI, are also briefly considered.
Collapse
Affiliation(s)
- Mary-Louise C Greer
- Department of Diagnostic Imaging, The Hospital for Sick Children; Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | | | - Li-Tal Pratt
- Pediatric Imaging Unit, Imaging Division, Sourasky Medical Center, Tel Aviv, Israel
| | - Don Soboleski
- Department of Diagnostic Imaging, Kingston Health Sciences Centre, Queen's University, Kingston, Ontario, Canada
| | - Gili Focht
- The Juliet Keidan Institute of Pediatric Gastroenterology, Shaare Zedek Medical Center, Jerusalem, Israel
| | - Denise A Castro
- Department of Diagnostic Imaging, Kingston Health Sciences Centre, Queen's University, Kingston, Ontario, Canada
| |
Collapse
|
9
|
Allocca M, Fiorino G, Bonifacio C, Peyrin-Biroulet L, Danese S. Noninvasive Multimodal Methods to Differentiate Inflamed vs Fibrotic Strictures in Patients With Crohn's Disease. Clin Gastroenterol Hepatol 2019; 17:2397-2415. [PMID: 30995529 DOI: 10.1016/j.cgh.2019.04.025] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 04/08/2019] [Accepted: 04/10/2019] [Indexed: 02/07/2023]
Abstract
Fibrotic strictures occur in 30% of patients with Crohn's disease (CD). However, there are no therapeutic agents that prevent or reverse fibrotic strictures. Strictures are treated by endoscopic dilatation procedures and surgical procedures, but there are high rates of recurrence. Two antifibrotic agents (nintedanib and pirfenidone) recently were approved for the treatment of idiopathic pulmonary fibrosis and inhibitors of Rho-associated protein kinases 1 and 2 reversed fibrosis in mice with chronic intestinal inflammation. Cross-sectional imaging techniques, such as magnetic resonance (MR) enterography, computed tomography enterography, and bowel ultrasound, are used to assess small-bowel and CD-related complications, including strictures. It is important to be able to determine the degree of inflammation and fibrosis in strictures to select the best therapy; this can be a challenge because inflammation and fibrosis co-exist to varying degrees in a damaged bowel segment. Delayed gadolinium enhancement, magnetization transfer MR imaging, and ultrasound elastography seem to be promising tools for assessing fibrosis in patients with CD. We review noninvasive techniques for fibrosis assessment, including analyses of genetic, epigenetic, and protein markers. We discuss the potential of imaging techniques such as diffusion-weighted and magnetization transfer MR imaging, strain elastography, shear-wave imaging, and positron emission tomography to guide therapeutic decisions for patients with stricturing CD.
Collapse
Affiliation(s)
- Mariangela Allocca
- Inflammatory Bowel Disease Centre, Humanitas Clinical and Research Centre, Rozzano, Milan, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Milan, Italy
| | - Gionata Fiorino
- Inflammatory Bowel Disease Centre, Humanitas Clinical and Research Centre, Rozzano, Milan, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Milan, Italy
| | - Cristiana Bonifacio
- Division of Diagnostic Radiology, Humanitas Clinical and Research Centre, Rozzano, Milano, Italy
| | - Laurent Peyrin-Biroulet
- Department of Gastroenterology and Inserm U954, University Hospital of Nancy, Lorraine University, Nancy, France
| | - Silvio Danese
- Inflammatory Bowel Disease Centre, Humanitas Clinical and Research Centre, Rozzano, Milan, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Milan, Italy.
| |
Collapse
|
10
|
Usefulness of diffusion-weighted MRI in the initial assessment of osseous sarcomas in children and adolescents. Pediatr Radiol 2019; 49:1201-1208. [PMID: 31203404 DOI: 10.1007/s00247-019-04436-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 04/01/2019] [Accepted: 05/21/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Concern regarding gadolinium deposition in the brain after repeated administration of intravenous gadolinium-based contrast agents has prompted evaluation of imaging alternatives. OBJECTIVE The study purpose was to determine if magnetic resonance imaging (MRI) using conventional sequences with diffusion-weighted imaging (DWI) instead of gadolinium-based contrast-enhanced MRI is valid for local staging and guiding biopsies in osseous sarcomas. MATERIALS AND METHODS Initial pretreatment MRI with DWI and gadolinium-based contrast-enhanced images in patients ≤ 18 years with histopathologically proven osseous sarcomas were included. Two radiologists blinded to collated demographic and clinical data, independently reviewed conventional/DWI and conventional/gadolinium-based contrast-enhanced MRI then conventional sequences alone, recording tumor size, skip lesions, necrosis, neurovascular invasion, enlarged lymph nodes and diffusion restriction. Discrepancies were resolved by a third reader. A single reader measured apparent diffusion coefficient (ADC) values in non-necrotic tumors, then correlated minimum ADC values -- with and without normalization to skeletal muscle -- with relative enhancement. RESULTS Twenty-one patients (mean age: 11.3±4.2 years, 15 [71%] females) had 14 osteosarcomas and 7 Ewing sarcomas, 50% centered in the femur. Conventional/DWI versus conventional/gadolinium-based contrast-enhanced MRI showed agreement for tumor size estimation with significant associations for necrosis (P=0.021), neurovascular involvement (P<0.001) and enlarged lymph nodes (P=0.005). Diagnostic accuracy of conventional/DWI is comparable to conventional/gadolinium-based contrast-enhanced MRI and superior to conventional sequences alone. Comparison between minimum ADC values and relative enhancement showed no correlation (P>0.05). CONCLUSION Significant associations of key imaging features in the initial assessment of osseous sarcomas support DWI as an alternative to gadolinium-based contrast-enhanced MRI. The lack of association between ADC values and relative enhancement suggests that they measure independent constructs, DWI dependent upon tumor cellularity and perfusion.
Collapse
|
11
|
Argollo M, Gilardi D, Roda G, Fiorino G, Peyrin-Biroulet L, Danese S. Anti-fibrotic Drugs for Crohn’s Disease: Ready for Prime Time? Curr Pharm Des 2019; 25:47-56. [DOI: 10.2174/1381612825666190308100844] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 03/01/2019] [Indexed: 12/17/2022]
Abstract
Intestinal fibrosis, driven by chronic inflammation in Crohn’s disease, can be defined as an excessive
accumulation of extracellular matrix in the affected gut segment ultimately leading to an impaired wound healing
and cumulative tissue damage, possibly resulting in organ dysfunction, formation of stenotic lesions and necessity
of surgical intervention. Despite continuous advances in developing novel treatment modalities targeting different
pathways to control chronic gut inflammation in CD, no effective anti-fibrotic agents have been released, to date.
Thus, a better understanding of the molecular and cellular mechanisms underlying intestinal fibrosis is key to
move this area of investigation forward.
Collapse
Affiliation(s)
- Marjorie Argollo
- IBD Centre, Humanitas Clinical and Research Centre, Rozzano, Milan, Italy
| | - Daniela Gilardi
- IBD Centre, Humanitas Clinical and Research Centre, Rozzano, Milan, Italy
| | - Giulia Roda
- IBD Centre, Humanitas Clinical and Research Centre, Rozzano, Milan, Italy
| | - Gionata Fiorino
- IBD Centre, Humanitas Clinical and Research Centre, Rozzano, Milan, Italy
| | - Laurent Peyrin-Biroulet
- Department of Gastroenterology and Inserm U954, Nancy University Hospital, Lorraine University, Vandoeuvre, France
| | - Silvio Danese
- IBD Centre, Humanitas Clinical and Research Centre, Rozzano, Milan, Italy
| |
Collapse
|
12
|
IVIM with fractional perfusion as a novel biomarker for detecting and grading intestinal fibrosis in Crohn’s disease. Eur Radiol 2018; 29:3069-3078. [DOI: 10.1007/s00330-018-5848-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 10/03/2018] [Accepted: 10/22/2018] [Indexed: 01/18/2023]
|
13
|
Milani B, Ledoux JB, Rotzinger DC, Kanemitsu M, Vallée JP, Burnier M, Pruijm M. Image acquisition for intravoxel incoherent motion imaging of kidneys should be triggered at the instant of maximum blood velocity: evidence obtained with simulations and in vivo experiments. Magn Reson Med 2018; 81:583-593. [DOI: 10.1002/mrm.27393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 05/14/2018] [Accepted: 05/15/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Bastien Milani
- Département de Medecine, Service de Néphrologie; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
- Département de Radiologie; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
- Center for Biomedical Imaging; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
| | - Jean-Baptiste Ledoux
- Département de Radiologie; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
- Center for Biomedical Imaging; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
| | - David C. Rotzinger
- Département de Radiologie; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
| | - Michiko Kanemitsu
- Département de Medecine, Service de Néphrologie; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
| | - Jean-Paul Vallée
- Département d'Imagerie et des Sciences de l'information Médicale; Hôpitaux Universitaires de Genève; Genève Switzerland
| | - Michel Burnier
- Département de Medecine, Service de Néphrologie; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
| | - Menno Pruijm
- Département de Medecine, Service de Néphrologie; Centre Hospitalier Universitaire Vaudois; Vaud Switzerland
| |
Collapse
|
14
|
Hectors SJ, Gordic S, Semaan S, Bane O, Hirten R, Jia X, Colombel JF, Taouli B. Diffusion and perfusion MRI quantification in ileal Crohn's disease. Eur Radiol 2018; 29:993-1002. [PMID: 30019143 DOI: 10.1007/s00330-018-5627-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/12/2018] [Accepted: 06/21/2018] [Indexed: 02/06/2023]
Abstract
OBJECTIVES To quantify intravoxel incoherent motion (IVIM)-DWI and dynamic contrast-enhanced (DCE)-MRI parameters in normal and abnormal ileal segments in Crohn's disease (CD) patients and to assess the association of these parameters with clinical and MRI-based measurements of CD activity. METHODS In this prospective study, 27 CD patients (M/F 18/9, mean age 42 years) underwent MR enterography, including IVIM-DWI and DCE-MRI. IVIM-DWI and DCE-MRI parameters were quantified in normal and abnormal small bowel segments, the latter identified by the presence of inflammatory changes. MRI parameter differences between normal and abnormal bowel were tested using Wilcoxon signed-rank tests. IVIM-DWI and DCE-MRI parameters were correlated with clinical data (C-reactive protein, Harvey-Bradshaw Index), conventional MRI parameters (wall thickness, length of involvement) and MRI activity scores (MaRIA, Clermont). Diagnostic performance of (combined) parameters for differentiation between normal and abnormal bowel was determined using ROC analysis. RESULTS The DCE-MRI parameters peak concentration Cpeak, upslope, area-under-the-curve at 60s (AUC60), Ktrans and ve were significantly increased (p<0.023), while IVIM-DWI parameters perfusion fraction (PF) and ADC were significantly decreased (p<0.001) in abnormal bowel segments. None of the DCE-MRI and IVIM-DWI parameters correlated with clinical parameters (p>0.105). DCE-MRI parameters exhibited multiple significant correlations with wall thickness (Cpeak, upslope, AUC60, Ktrans; r range 0.431-0.664, p<0.025) and MaRIA/Clermont scores (Cpeak, AUC60, Ktrans; r range 0.441-0.617, p<0.021). Combined Ktrans+ve+PF+ADC showed highest AUC (0.963) for differentiation between normal and abnormal bowel, while ADC performed best for individual parameters (AUC=0.800). CONCLUSIONS DCE-MRI and IVIM-DWI, particularly when used in combination, are promising for non-invasive evaluation of small bowel CD. KEY POINTS • IVIM-DWI and DCE-MRI parameters were significantly different between normal and abnormal bowel segments in CD patients. • DCE-MRI parameters showed a significant association with wall thickness and MRI activity scores. • Combination of IVIM-DWI and DCE-MRI parameters led to the highest diagnostic performance for differentiation between normal and abnormal bowel segments, while ADC showed the highest diagnostic performance of individual parameters.
Collapse
Affiliation(s)
- Stefanie J Hectors
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sonja Gordic
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Sahar Semaan
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Octavia Bane
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Robert Hirten
- IBD Center, Division of Gastroenterology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Xiaoyu Jia
- Department of Population Health Science and Policy, Institute for Healthcare Delivery Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jean-Frederic Colombel
- IBD Center, Division of Gastroenterology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Bachir Taouli
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. .,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| |
Collapse
|
15
|
Diffusion-weighted imaging for evaluating inflammatory activity in Crohn's disease: comparison with histopathology, conventional MRI activity scores, and faecal calprotectin. Abdom Radiol (NY) 2017; 42:115-123. [PMID: 27567607 PMCID: PMC5243884 DOI: 10.1007/s00261-016-0863-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Purpose To evaluate whether the extent of enteric diffusion-weighted imaging (DWI) signal abnormality reflects inflammatory burden in Crohn’s disease (CD), and to compare qualitative and quantitative grading. Methods 69 CD patients (35 male, age 16–78) undergoing MR enterography with DWI (MRE-D) and the same-day faecal calprotectin (cohort 1) were supplemented by 29 patients (19 male, age 16–70) undergoing MRE-D and terminal ileal biopsy (cohort 2). Global (cohort 1) and terminal ileal (cohort 2) DWI signal was graded (0 to 3) by 2 radiologists and segmental apparent diffusion coefficient (ADC) calculated. Data were compared to calprotectin and a validated MRI activity score [MEGS] (cohort 1), and a histopathological activity score (eAIS) (cohort 2) using nonparametric testing and rank correlation. Results Patients with normal (grades 0 and 1) DWI signal had lower calprotectin and MEGS than those with abnormal signal (grades 2 and 3) (160 vs. 492 μg/l, p = 0.0004, and 3.3 vs. 21, p < 0.0001), respectively. Calprotectin was lower if abnormal DWI affected <10 cm of small bowel compared to diffuse small and large bowel abnormality (236 vs. 571 μg, p = 0.009). The sensitivity and specificity for active disease (calprotectin > 120 μg/l) were 83% and 52%, respectively. There was a negative correlation between ileal MEGS and ADC (r = −0.41, p = 0.017). There was no significant difference in eAIS between qualitative DWI scores (p = 0.42). Mean ADC was not different in those with and without histological inflammation (2077 vs. 1622 × 10−6mm2/s, p = 0.10) Conclusions Qualitative grading of DWI signal has utility in defining the burden of CD activity. Quantitative ADC measurements have poor discriminatory ability for segmental disease activity.
Collapse
|
16
|
Accuracy and interobserver agreement of diffusion-weighted imaging in pediatric inflammatory bowel disease. Clin Imaging 2017; 41:14-22. [DOI: 10.1016/j.clinimag.2016.09.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 08/25/2016] [Accepted: 09/22/2016] [Indexed: 12/14/2022]
|
17
|
Yao Y, Zhang S, Tang X, Zhang S, Shi J, Zhu W, Zhu W. Intravoxel incoherent motion diffusion-weighted imaging in stroke patients: initial clinical experience. Clin Radiol 2016; 71:938.e11-6. [DOI: 10.1016/j.crad.2016.04.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 03/14/2016] [Accepted: 04/14/2016] [Indexed: 11/30/2022]
|
18
|
Afacan O, Gholipour A, Mulkern RV, Barnewolt CE, Estroff JA, Connolly SA, Parad RB, Bairdain S, Warfield SK. Fetal lung apparent diffusion coefficient measurement using diffusion-weighted MRI at 3 Tesla: Correlation with gestational age. J Magn Reson Imaging 2016; 44:1650-1655. [PMID: 27159847 DOI: 10.1002/jmri.25294] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/08/2016] [Accepted: 04/10/2016] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To evaluate the feasibility of using diffusion-weighted magnetic resonance imaging (DW-MRI) to assess the fetal lung apparent diffusion coefficient (ADC) at 3 Tesla (T). MATERIALS AND METHODS Seventy-one pregnant women (32 second trimester, 39 third trimester) were scanned with a twice-refocused Echo-planar diffusion-weighted imaging sequence with 6 different b-values in 3 orthogonal diffusion orientations at 3T. After each scan, a region-of-interest (ROI) mask was drawn to select a region in the fetal lung and an automated robust maximum likelihood estimation algorithm was used to compute the ADC parameter. The amount of motion in each scan was visually rated. RESULTS When scans with unacceptable levels of motion were eliminated, the lung ADC values showed a strong association with gestational age (P < 0.01), increasing dramatically between 16 and 27 weeks and then achieving a plateau around 27 weeks. CONCLUSION We show that to get reliable estimates of ADC values of fetal lungs, a multiple b-value acquisition, where motion is either corrected or considered, can be performed. J. Magn. Reson. Imaging 2016;44:1650-1655.
Collapse
Affiliation(s)
- Onur Afacan
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Ali Gholipour
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Robert V Mulkern
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Carol E Barnewolt
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Advanced Fetal Care Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Judy A Estroff
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Advanced Fetal Care Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Susan A Connolly
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Advanced Fetal Care Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Richard B Parad
- Advanced Fetal Care Center, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Pediatric Newborn Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Sigrid Bairdain
- Harvard Medical School, Boston, Massachusetts, USA.,Department of Surgery, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Simon K Warfield
- Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
19
|
Greer MLC. How we do it: MR enterography. Pediatr Radiol 2016; 46:818-28. [PMID: 27229500 DOI: 10.1007/s00247-016-3596-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 02/04/2016] [Accepted: 02/25/2016] [Indexed: 01/08/2023]
Abstract
Magnetic resonance enterography (MRE) now plays a central role in diagnosing pediatric inflammatory bowel disease (IBD), and its role in other intestinal pathologies such as scleroderma is gradually expanding. MRE helps distinguish between Crohn disease and ulcerative colitis, defining extent and severity. Standard MRE protocols can be optimized in children and adolescents to be diagnostic and well tolerated, both of which are important with increasing use of serial MRE in pediatric IBD for monitoring treatment response and evaluating complications. MRI is especially suited to this role given its lack of ionizing radiation. MRE compliance can be improved through patient education. Differing from adult MRE, pediatric MRE protocols use weight-based formulas to calculate oral and intravenous contrast media and antispasmodic agent doses, using either hyoscine-N-butylbromide or glucagon. Nausea is more commonly experienced with glucagon; however vomiting occurs in <10% of children with either agent. Standard and advanced sequences applied in adults are also used in children and adolescents. These include static and cinematic balanced steady-state free precession sequences, single-shot T2-weighted sequences, diffusion-weighted imaging and pre- and post-contrast 3-D T1-weighted gradient echo sequences. Magnetization transfer imaging and quantitative assessment of bowel to distinguish inflammation and fibrosis are not yet standard in pediatric MRE, but show promise.
Collapse
Affiliation(s)
- Mary-Louise C Greer
- Department of Diagnostic Imaging, The Hospital for Sick Children, 555 University Ave., Toronto, Ontario, M5G 1X8, Canada. .,Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.
| |
Collapse
|
20
|
Intravoxel incoherent motion analysis of abdominal organs: computation of reference parameters in a large cohort of C57Bl/6 mice and correlation to microvessel density. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2016; 29:751-63. [DOI: 10.1007/s10334-016-0540-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 02/19/2016] [Accepted: 02/22/2016] [Indexed: 12/30/2022]
|
21
|
Kurugol S, Freiman M, Afacan O, Perez-Rossello JM, Callahan MJ, Warfield SK. Spatially-constrained probability distribution model of incoherent motion (SPIM) for abdominal diffusion-weighted MRI. Med Image Anal 2016; 32:173-83. [PMID: 27111049 DOI: 10.1016/j.media.2016.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 10/22/2015] [Accepted: 03/25/2016] [Indexed: 12/15/2022]
Abstract
Quantitative diffusion-weighted MR imaging (DW-MRI) of the body enables characterization of the tissue microenvironment by measuring variations in the mobility of water molecules. The diffusion signal decay model parameters are increasingly used to evaluate various diseases of abdominal organs such as the liver and spleen. However, previous signal decay models (i.e., mono-exponential, bi-exponential intra-voxel incoherent motion (IVIM) and stretched exponential models) only provide insight into the average of the distribution of the signal decay rather than explicitly describe the entire range of diffusion scales. In this work, we propose a probability distribution model of incoherent motion that uses a mixture of Gamma distributions to fully characterize the multi-scale nature of diffusion within a voxel. Further, we improve the robustness of the distribution parameter estimates by integrating spatial homogeneity prior into the probability distribution model of incoherent motion (SPIM) and by using the fusion bootstrap solver (FBM) to estimate the model parameters. We evaluated the improvement in quantitative DW-MRI analysis achieved with the SPIM model in terms of accuracy, precision and reproducibility of parameter estimation in both simulated data and in 68 abdominal in-vivo DW-MRIs. Our results show that the SPIM model not only substantially reduced parameter estimation errors by up to 26%; it also significantly improved the robustness of the parameter estimates (paired Student's t-test, p < 0.0001) by reducing the coefficient of variation (CV) of estimated parameters compared to those produced by previous models. In addition, the SPIM model improves the parameter estimates reproducibility for both intra- (up to 47%) and inter-session (up to 30%) estimates compared to those generated by previous models. Thus, the SPIM model has the potential to improve accuracy, precision and robustness of quantitative abdominal DW-MRI analysis for clinical applications.
Collapse
Affiliation(s)
- Sila Kurugol
- Computational Radiology Laboratory; Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States.
| | - Moti Freiman
- Computational Radiology Laboratory; Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States
| | - Onur Afacan
- Computational Radiology Laboratory; Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States
| | - Jeannette M Perez-Rossello
- Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States
| | - Michael J Callahan
- Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States
| | - Simon K Warfield
- Computational Radiology Laboratory; Department of Radiology, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, United States
| |
Collapse
|
22
|
Kovanlikaya A, Beneck D, Rose M, Renjen P, Dunning A, Solomon A, Sockolow R, Brill PW. Quantitative apparent diffusion coefficient (ADC) values as an imaging biomarker for fibrosis in pediatric Crohn's disease: preliminary experience. ACTA ACUST UNITED AC 2016; 40:1068-74. [PMID: 25248794 DOI: 10.1007/s00261-014-0247-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
PURPOSE To compare histopathology with ADC values in strictured bowel segments in pediatric patients with known Crohn's disease and surgical bowel resection. METHODS Magnetic resonance enterography (MRE) images of 14 subjects with Crohn's disease who had surgical bowel resection for strictures were retrospectively reviewed. Five of 14 subjects had DWI (b=0, 500, 1000) sequences included in the MRE study. ADC measurements were made by placing ROI's in the strictured bowel wall and compared to full-thickness histologic analysis of resected specimens. ADC values were also compared to control ADC measurements (in normal and inflamed-nonstenotic bowel segments) as well as the mean ADC values of Crohn's patients published in the literature. RESULTS All five subjects had transmural fibrosis. The mean ADC value with b = 500 was 0.92 ± 0.10 × 10(-3) mm(2)/s and with b = 1000 was 0.8 ± 0.05 × 10(-3) mm(2)/s. There was a significant difference in ADC values between strictures and inflamed-nonstenotic segments (p=0.0143) and between normal and diseased bowel segments (p=0.009-0.0143). CONCLUSIONS Quantitative ADC measures of transmural fibrosis are lower compared to the reported values of inflammation in Crohn's disease. To our knowledge, this is the first pediatric pilot study to investigate the correlation of quantitative DWI with histology of surgical specimens in pediatric patients with Crohn's disease. Our results are comparable to a recently published study in adult Crohn's patients showing a significant correlation between a decrease in ADC values and fibrosis.
Collapse
Affiliation(s)
- A Kovanlikaya
- Department of Radiology, Weill Cornell Medical College, New York Presbyterian Hospital, 525 E 68th St., New York, NY, 1006, USA,
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Rosenbaum DG, Rose ML, Solomon AB, Giambrone AE, Kovanlikaya A. Longitudinal diffusion-weighted imaging changes in children with small bowel Crohn's disease: preliminary experience. ACTA ACUST UNITED AC 2016; 40:1075-80. [PMID: 25808716 DOI: 10.1007/s00261-015-0403-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
PURPOSE Crohn's disease has been associated with restricted diffusion in diseased small bowel segments on diffusion-weighted imaging (DWI). However, data addressing longitudinal changes in DWI findings and their potential clinical ramifications in the pediatric population are lacking. The purpose of this study was to follow DWI changes in diseased small bowel segments between serial magnetic resonance enterography (MRE) examinations, and to correlate these changes with other imaging parameters and clinical status. METHODS This retrospective study evaluated patients less than 21 years of age undergoing serial MRE examinations including DWI for Crohn's disease involving the small bowel. All patients carried a diagnosis of Crohn's disease established by pathology or corroborative clinical and imaging findings. Longitudinal changes in mean apparent diffusion coefficient (ADC) values within the wall of affected small bowel lesions were recorded and normalized to both unaffected bowel and skeletal muscle. ADC changes were correlated with qualitative imaging phenotype, as reflected by a defined set of non-DWI imaging parameters, as well as with clinical disease activity. RESULTS Seventeen lesions were evaluated longitudinally, distributed among 13 patients (9 boys and 4 girls, mean age at baseline 16.6 years), each of whom had two sequential MRE examinations. Lesions demonstrating a fibrostenotic imaging phenotype at follow-up MRE had a significantly lower change in mean ADC value between examinations than lesions that did not have a fibrostenotic imaging phenotype (p = 0.0005), an effect that persisted when ADC values were normalized to unaffected bowel and skeletal muscle. Across all studies, lesions with a fibrostenotic imaging phenotype had lower ADC values than those with an inflammatory imaging phenotype, which were in turn lower than those with a normal imaging phenotype (p = 0.0001). CONCLUSION Patterns of longitudinal DWI changes in Crohn's disease may differ among small bowel lesions depending upon their specific natural histories. These findings may assist in the evaluation of the ADC value as a potential imaging surrogate when evaluating lesion status, particularly as it pertains to relative contributions of inflammation and fibrosis.
Collapse
Affiliation(s)
- Daniel G Rosenbaum
- Department of Radiology, Weill Cornell Medical College/NewYork-Presbyterian Hospital, 525 E. 68th St., New York, NY, 10065, USA,
| | | | | | | | | |
Collapse
|
24
|
Shenoy-Bhangle AS, Nimkin K, Aranson T, Gee MS. Value of diffusion-weighted imaging when added to magnetic resonance enterographic evaluation of Crohn disease in children. Pediatr Radiol 2016; 46:34-42. [PMID: 26238966 DOI: 10.1007/s00247-015-3438-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Revised: 06/10/2015] [Accepted: 07/13/2015] [Indexed: 01/14/2023]
Abstract
BACKGROUND MR enterography is increasingly utilized for noninvasive evaluation of disease activity in young patients with Crohn disease and has great impact on clinical management. Diffusion-weighted imaging (DWI) is a rapid MR imaging technique that measures molecular diffusion of water and is sensitive to the inflammatory process; however, its value to MR enterography has not been rigorously evaluated. OBJECTIVE To determine whether the addition of DWI to MR enterography is helpful in evaluating Crohn disease activity in young patients when compared to a histological reference. MATERIALS AND METHODS In this single-institution retrospective study, we searched an imaging database for the period January 2010 to December 2012 to identify patients age 19 years and younger who had MR enterography with diffusion-weighted imaging (DWI). We used an electronic medical record search to identify those who had MR enterography and colonoscopy performed within 28 days of each other. All MR enterography scans were performed on a 1.5-T or 3-T clinical MR scanner with phased-array torso coil configuration using standard pulse sequences as well as axial DWI with b values of 50, 400 and 800. Bowel segments were evaluated for disease activity based on standard MR enterography sequences; in addition, segmental apparent diffusion coefficient (ADC) values were calculated based on DWI. Histological reference for disease activity was based on assessment for mucosal inflammatory changes on endoscopic biopsy. MR enterography and DWI evaluation were performed in a blinded fashion with respect to histological results. RESULTS We included imaging of 78 bowel segments from 27 patients (mean age 14.5 ± 3.02 years) with known Crohn disease in the study. The mean ADC for bowel segments with active disease was 1.56 ± 0.7 × 10(3) mm(2)/s compared with 2.58 ± 1.4 × 10(3) mm(2)/s for segments without active disease, a difference that was statistically significant (P < 0.01, Student's t-test). Using a threshold value of 2.0 × 10(3) mm(2)/s, DWI demonstrated lower accuracy (64.1%) but higher sensitivity (78.8%) for detecting active disease compared with standard MR enterography (69.2% and 54.6%, respectively). Combining DWI with MR enterography, using DWI as the initial screen and MR enterography afterward to reduce false negativity, led to a significant increase in accuracy (76.9%; P = 0.03, McNemar's test) compared with either imaging technique alone. CONCLUSION Although DWI does not perform as well as standard MR enterography for detection of active Crohn disease, the combination of DWI and MR enterography increases imaging accuracy for determining disease activity compared with either technique alone. These results indicate that DWI adds value to MR enterography and supports the incorporation of DWI into MR enterography protocols for evaluation of Crohn disease in young patients.
Collapse
Affiliation(s)
- Anuradha S Shenoy-Bhangle
- Division of Abdominal Imaging/Community Radiology, Shapiro Clinical Center, Beth Israel Deaconess Medical Center, 330 Brookline Ave., 4th Floor, Boston, MA, 02215, USA.
| | - Katherine Nimkin
- Division of Pediatric Imaging, Department of Radiology, Massachusetts General Hospital for Children, Boston, MA, USA
| | - Thomas Aranson
- Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia, Canada
| | - Michael S Gee
- Division of Pediatric Imaging, Department of Radiology, Massachusetts General Hospital for Children, Boston, MA, USA.,Division of Abdominal Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
| |
Collapse
|
25
|
The Role of MR Enterography in Assessing Crohn's Disease Activity and Treatment Response. Gastroenterol Res Pract 2015; 2016:8168695. [PMID: 26819611 PMCID: PMC4706951 DOI: 10.1155/2016/8168695] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/23/2015] [Accepted: 08/27/2015] [Indexed: 12/17/2022] Open
Abstract
MR enterography (MRE) has become the primary imaging modality in the assessment of Crohn's disease (CD) in both children and adults at many institutions in the United States and worldwide, primarily due to its noninvasiveness, superior soft tissue contrast, and lack of ionizing radiation. MRE technique includes distention of the small bowel with oral contrast media with the acquisition of T2-weighted, balanced steady-state free precession, and multiphase T1-weighted fat suppressed gadolinium contrast-enhanced sequences. With the introduction of molecule-targeted biologic agents into the clinical setting for CD and their potential to reverse the inflammatory process, MRE is increasingly utilized to evaluate disease activity and response to therapy as an imaging complement to clinical indices or optical endoscopy. New and emerging MRE techniques, such as diffusion-weighted imaging (DWI), magnetization transfer, ultrasmall superparamagnetic iron oxide- (USPIO-) enhanced MRI, and PET-MR, offer the potential for an expanded role of MRI in detecting occult disease activity, evaluating early treatment response/resistance, and differentiating inflammatory from fibrotic strictures. Familiarity with MR enterography is essential for radiologists and gastroenterologists as the technique evolves and is further incorporated into the clinical management of CD.
Collapse
|
26
|
Taimouri V, Afacan O, Perez-Rossello JM, Callahan MJ, Mulkern RV, Warfield SK, Freiman M. Spatially constrained incoherent motion method improves diffusion-weighted MRI signal decay analysis in the liver and spleen. Med Phys 2015; 42:1895-903. [PMID: 25832079 DOI: 10.1118/1.4915495] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To evaluate the effect of the spatially constrained incoherent motion (SCIM) method on improving the precision and robustness of fast and slow diffusion parameter estimates from diffusion-weighted MRI in liver and spleen in comparison to the independent voxel-wise intravoxel incoherent motion (IVIM) model. METHODS We collected diffusion-weighted MRI (DW-MRI) data of 29 subjects (5 healthy subjects and 24 patients with Crohn's disease in the ileum). We evaluated parameters estimates' robustness against different combinations of b-values (i.e., 4 b-values and 7 b-values) by comparing the variance of the estimates obtained with the SCIM and the independent voxel-wise IVIM model. We also evaluated the improvement in the precision of parameter estimates by comparing the coefficient of variation (CV) of the SCIM parameter estimates to that of the IVIM. RESULTS The SCIM method was more robust compared to IVIM (up to 70% in liver and spleen) for different combinations of b-values. Also, the CV values of the parameter estimations using the SCIM method were significantly lower compared to repeated acquisition and signal averaging estimated using IVIM, especially for the fast diffusion parameter in liver (CVIV IM = 46.61 ± 11.22, CVSCIM = 16.85 ± 2.160, p < 0.001) and spleen (CVIV IM = 95.15 ± 19.82, CVSCIM = 52.55 ± 1.91, p < 0.001). CONCLUSIONS The SCIM method characterizes fast and slow diffusion more precisely compared to the independent voxel-wise IVIM model fitting in the liver and spleen.
Collapse
Affiliation(s)
- Vahid Taimouri
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Onur Afacan
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Jeannette M Perez-Rossello
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Michael J Callahan
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Robert V Mulkern
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Simon K Warfield
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Moti Freiman
- Computational Radiology Laboratory, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| |
Collapse
|
27
|
Bhatnagar G, Dikaios N, Prezzi D, Vega R, Halligan S, Taylor SA. Changes in dynamic contrast-enhanced pharmacokinetic and diffusion-weighted imaging parameters reflect response to anti-TNF therapy in Crohn's disease. Br J Radiol 2015; 88:20150547. [PMID: 26402217 DOI: 10.1259/bjr.20150547] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE To investigate the effect of tumour necrosis factor (TNF)-α antagonists on MRI dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI) parameters in Crohn's disease (CD). METHODS 42 patients with CD (median age 24 years; 22 females) commencing anti-TNF-α therapy with baseline and follow-up (median 51 weeks) 1.5-T MR enterography (MRE) were retrospectively identified. MRE included DCE (n = 20) and/or multi-b-value DWI (n = 17). Slope of enhancement (SoE), maximum enhancement (ME), area under the time-intensity curve (AUC), Ktrans (transfer constant), ve (fractional volume of the extravascular-extracellular space), apparent diffusion coefficient (ADC) and ADCfast/slow were derived from the most inflamed bowel segments. A physician global assessment of disease activity (remission, mild, moderate and severe) at the time of MRE was assigned, and the cohort was divided into responders and non-responders. Data were compared using Mann-Whitney U test and analysis of variance. RESULTS Follow-up Ktrans, ME, SoE, AUC and ADCME changed significantly in clinical responders but not in non-responders, baseline {[median [interquartile range (IQR)]: 0.42 (0.38), 1.24 (0.52), 0.18 (0.17), 17.68 (4.70) and 1.56 mm(2) s(-1) (0.39 mm(2) s(-1)) vs follow-up [median (IQR): 0.15 (0.22), 0.50 (0.54), 0.07 (0.1), 14.73 (2.06) and 2.14 mm(2) s(-1) (0.62 mm(2) s(-1)), for responders, respectively, p = 0.006 to p = 0.037}. SoE was higher and ME and AUC lower for patients in remission than for those with severe activity [mean (standard deviation): 0.55 (0.46), 0.49 (0.28), 14.32 (1.32)] vs [0.32 (0.37), 2.21 (2.43) and 23.05 (13.66), respectively p = 0.017 to 0.033]. ADC was significantly higher for patients in remission [2.34 mm(2) s(-1) (0.67 mm(2) s(-1))] than for those with moderate [1.59 mm(2) s(-1) (0.26 mm(2) s(-1))] (p = 0.005) and severe disease [1.63 mm(2) s(-1) (0.21 mm(2) s(-1))] (p = 0.038). CONCLUSION DCE and DWI parameters change significantly in responders to TNF-α antagonists and are significantly different according to clinically defined disease activity status. ADVANCES IN KNOWLEDGE DCE and DWI parameters change significantly in responders to TNF-α antagonists in CD, suggesting an effect on bowel wall vascularity.
Collapse
Affiliation(s)
| | - Nikolaos Dikaios
- 1 Centre for Medical Imaging, University College London, London, UK
| | - Davide Prezzi
- 1 Centre for Medical Imaging, University College London, London, UK.,2 Department of Cancer Imaging, King's College London, UCL CMI, London, UK
| | - Roser Vega
- 3 Gastroenterology Department, University College London Hospitals, UCLH, London, UK
| | - Steve Halligan
- 1 Centre for Medical Imaging, University College London, London, UK
| | - Stuart A Taylor
- 1 Centre for Medical Imaging, University College London, London, UK
| |
Collapse
|
28
|
Abstract
OBJECTIVE Pediatric patients with inflammatory bowel disease (IBD) commonly need repetitive imaging to assess disease activity and complications. Recently, MR enterography has become a first-line radiologic study in children with IBD because of improved image quality, excellent soft-tissue contrast resolution, and lack of ionizing radiation. The purpose of this article is to describe the use of diffusion-weighted imaging (DWI) in MR enterography and the evaluation of pediatric IBD. CONCLUSION Several contemporary publications have shown that DWI can be useful for assessing both pediatric and adult patients with IBD as an important adjunct pulse sequence. Specifically, DWI can be used to identify abnormal bowel segments, assess disease inflammatory activity, and detect and characterize a variety of extraintestinal IBD-related manifestations and complications.
Collapse
|
29
|
MRI diffusion-weighted imaging (DWI) in pediatric small bowel Crohn disease: correlation with MRI findings of active bowel wall inflammation. Pediatr Radiol 2013; 43:1077-85. [PMID: 23949929 DOI: 10.1007/s00247-013-2712-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 04/01/2013] [Accepted: 04/05/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND Restricted diffusion on diffusion-weighted imaging (DWI) sequences during magnetic resonance enterography (MRE) has been shown in segments of bowel affected by Crohn disease. However, the exact meaning of this finding, particularly within the pediatric Crohn disease population, is poorly understood. OBJECTIVE The purpose of this study was to determine the significance of bowel wall restricted diffusion in children with small bowel Crohn disease by correlating apparent diffusion coefficient (ADC) values with other MRI markers of disease activity. MATERIALS AND METHODS A retrospective review of pediatric patients (≤ 18 years of age) with Crohn disease terminal ileitis who underwent MRE with DWI at our institution between May 1, 2009 and May 31, 2011 was undertaken. All of the children had either biopsy-proven Crohn disease terminal ileitis or clinically diagnosed Crohn disease, including terminal ileal involvement by imaging. The mean minimum ADC value within the wall of the terminal ileum was determined for each examination. ADC values were tested for correlation/association with other MRI findings to determine whether a relationship exists between bowel wall restricted diffusion and disease activity. RESULTS Forty-six MRE examinations with DWI in children with terminal ileitis were identified (23 girls and 23 boys; mean age, 14.3 years). There was significant negative correlation or association between bowel wall minimum ADC value and established MRI markers of disease activity, including degree of bowel wall thickening (R = (-)0.43; P = 0.003), striated pattern of arterial enhancement (P = 0.01), degree of arterial enhancement (P = 0.01), degree of delayed enhancement (P = 0.045), amount of mesenteric inflammatory changes (P < 0.0001) and presence of a stricture (P = 0.02). ADC values were not significantly associated with bowel wall T2-weighted signal intensity, length of disease involvement or mesenteric fibrofatty proliferation. CONCLUSION Increasing bowel wall restricted diffusion (lower ADC values) is associated with multiple MRI findings that are traditionally associated with active inflammation in pediatric small bowel Crohn disease.
Collapse
|
30
|
Abstract
This article addresses the current technique and protocols for magnetic resonance (MR) enterography, with a primary focus on inflammatory bowel disease (IBD) and a secondary detailed discussion of other diseases of the small bowel beyond IBD. A brief discussion of MR imaging for appendicitis is included, but the evaluation of appendicitis does not require an enterographic protocol. The focused key points and approach presented in this article are intended to enhance the reader's understanding to help improve patient compliance with the MR enterographic studies, overcome challenges, and improve interpretation.
Collapse
|
31
|
Reliable estimation of incoherent motion parametric maps from diffusion-weighted MRI using fusion bootstrap moves. Med Image Anal 2013; 17:325-36. [PMID: 23434293 DOI: 10.1016/j.media.2012.12.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 12/03/2012] [Accepted: 12/10/2012] [Indexed: 11/23/2022]
Abstract
Diffusion-weighted MRI has the potential to provide important new insights into physiological and microstructural properties of the body. The Intra-Voxel Incoherent Motion (IVIM) model relates the observed DW-MRI signal decay to parameters that reflect blood flow in the capillaries (D*), capillaries volume fraction (f), and diffusivity (D). However, the commonly used, independent voxel-wise fitting of the IVIM model leads to imprecise parameter estimates, which has hampered their practical usage. In this work, we improve the precision of estimates by introducing a spatially-constrained Incoherent Motion (IM) model of DW-MRI signal decay. We also introduce an efficient iterative "fusion bootstrap moves" (FBM) solver that enables precise parameter estimates with this new IM model. This solver updates parameter estimates by applying a binary graph-cut solver to fuse the current estimate of parameter values with a new proposal of the parameter values into a new estimate of parameter values that better fits the observed DW-MRI data. The proposals of parameter values are sampled from the independent voxel-wise distributions of the parameter values with a model-based bootstrap resampling of the residuals. We assessed both the improvement in the precision of the incoherent motion parameter estimates and the characterization of heterogeneous tumor environments by analyzing simulated and in vivo abdominal DW-MRI data of 30 patients, and in vivo DW-MRI data of three patients with musculoskeletal lesions. We found our IM-FBM reduces the relative root mean square error of the D* parameter estimates by 80%, and of the f and D parameter estimates by 50% compared to the IVIM model with the simulated data. Similarly, we observed that our IM-FBM method significantly reduces the coefficient of variation of parameter estimates of the D* parameter by 43%, the f parameter by 37%, and the D parameter by 17% compared to the IVIM model (paired Student's t-test, p<0.0001). In addition, we found our IM-FBM method improved the characterization of heterogeneous musculoskeletal lesions by means of increased contrast-to-noise ratio of 19.3%. The IM model and FBM solver combined, provide more precise estimate of the physiological model parameter values that describing the DW-MRI signal decay and a better mechanism for characterizing heterogeneous lesions than does the independent voxel-wise IVIM model.
Collapse
|