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Meyer HJ, Wienke A, Surov A. Can dynamic contrast enhanced MRI predict gleason score in prostate cancer? a systematic review and meta analysis. Urol Oncol 2021; 39:784.e17-784.e25. [PMID: 33934966 DOI: 10.1016/j.urolonc.2021.03.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/13/2021] [Accepted: 03/21/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND OBJECTIVES Multiparametric MRI has become a corner stone in diagnosis of prostate cancer (PC). DCE-MRI is used to quantify the influx of contrast media into tissues, which was shown to correlate with histopathology features. The present analysis sought to correlate DCE-MRI parameters with Gleason score (GS) based upon a large patient sample. MATERIAL AND METHODS MEDLINE library, Cochrane and SCOPUS databases were screened for the associations between DCE-MRI and GS in PC up to April 2020. The primary endpoint of the systematic review was the correlation between DCE-MRI parameters and GS and mean Ktrans and Kep and Ve values with standard deviation. In total, 13 studies with overall 894 patients were suitable for the analysis and included into the present study. RESULTS The highest correlation was identified for Ktrans with a pooled correlation coefficient of r = 0.36 (95% CI 0.14-0.59). A large overlap was identified between clinical significant and non-significant PC for all DCE-parameters, for Ktrans the pooled mean value of clinically non-significant PC was 0.32 min-1 [95% CI 0.13-0.51] and for clinically significant PC it was 0.45 min-1 (95% CI 0.25-0.64). CONCLUSION DCE-MRI cannot be used to predict GS in PC, and consequently cannot discriminate clinically significant from non-significant cancers.
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Affiliation(s)
- Hans-Jonas Meyer
- Department of Diagnostic and Interventional Radiology, University of Leipzig, Leipzig, Germany.
| | - Andreas Wienke
- Institute of Medical Epidemiology, Biostatistics, and Informatics, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Alexey Surov
- Department of Radiology and Nuclear Medicine, University of Magdeburg, Magdeburg, Germany
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2
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Fan X, Chatterjee A, Medved M, Oto A, Karczmar GS. Signal intensity form of the Tofts model for quantitative analysis of prostate dynamic contrast enhanced MRI data. Phys Med Biol 2021; 66:025002. [PMID: 33181487 DOI: 10.1088/1361-6560/abca02] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The aim of this study is to develop a signal intensity (S(t)) form of the standard Tofts pharmacokinetic model that avoids the need to calculate tissue contrast agent concentration (C(t)) as function of time (t). We refer to this as 'SI-Tofts' model. Physiological parameters (K trans and v e) calculated using the SI-Tofts and standard Tofts models were compared by using simulations and human prostate dynamic contrast enhanced (DCE) MRI data. This approach was also applied to the Patlak model to compare K trans values calculated from C(t) and S(t). Simulations were performed on DCE-MRI data from the quantitative imaging biomarkers alliance to validate SI-Tofts model. In addition, ultrafast DCE-MRI data were acquired from 18 prostate cancer patients on a Philips Achieva 3T-TX scanner. Regions-of-interest (ROIs) for prostate cancer, normal tissue, gluteal muscle, and iliac artery were manually traced. The C(t) was calculated for each ROI using the standard model with measured pre-contrast tissue T 1 values. Both the simulation and clinical results showed strong correlation (r = 0.87-0.99, p < 0.001) for K trans and v e calculated from the SI-Tofts and standard Tofts models. The SI-Tofts model with a correction factor using the T 1 ratio of blood to tissue significantly improved the K trans estimates. The correlation of K trans obtained from the Patlak model with C(t) vs S(t) was also strong (r = 0.95-0.99, p < 0.001). These preliminary results suggest that physiological parameters from DCE-MRI can be reliably estimated from the SI-Tofts model without contrast agent concentration calculation.
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Affiliation(s)
- Xiaobing Fan
- Department of Radiology, University of Chicago, Chicago, IL 60637, United States of America
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Lu Y, Ge S, Liu Y, Bai G. WITHDRAWN: The Changes of ADC Value, DCE-MRI Parameters and Their Influence on Neuropsychology in Prostate Cancer Patients after Endocrine Therapy Based on Magnetic Resonance Imaging. Neurosci Lett 2020:135221. [PMID: 32615249 DOI: 10.1016/j.neulet.2020.135221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/21/2020] [Accepted: 06/27/2020] [Indexed: 10/24/2022]
Abstract
This article has been withdrawn at the request of the Editor-in-Chief. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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Affiliation(s)
- Yang Lu
- Department of Radiology, The Affiliated Huaian No.1 People's Hospital of Nanjing Medical University, Huaian, 223300, Jiangsu, China
| | - Shang Ge
- Department of Radiology, The Affiliated Huaian No.1 People's Hospital of Nanjing Medical University, Huaian, 223300, Jiangsu, China
| | - Yan Liu
- Department of Radiology, The Affiliated Huaian No.1 People's Hospital of Nanjing Medical University, Huaian, 223300, Jiangsu, China
| | - Gengji Bai
- Department of Radiology, The Affiliated Huaian No.1 People's Hospital of Nanjing Medical University, Huaian, 223300, Jiangsu, China.
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Hectors SJ, Said D, Gnerre J, Tewari A, Taouli B. Luminal Water Imaging: Comparison With Diffusion-Weighted Imaging (DWI) and PI-RADS for Characterization of Prostate Cancer Aggressiveness. J Magn Reson Imaging 2020; 52:271-279. [PMID: 31961049 DOI: 10.1002/jmri.27050] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 12/14/2019] [Accepted: 12/16/2019] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Luminal water imaging (LWI), a multicomponent T2 mapping technique, has shown promise for prostate cancer (PCa) detection and characterization. PURPOSE To 1) quantify LWI parameters and apparent diffusion coefficient (ADC) in PCa and benign peripheral zone (PZ) tissues; and 2) evaluate the diagnostic performance of LWI, ADC, and PI-RADS parameters for differentiation between low- and high-grade PCa lesions. STUDY TYPE Prospective. SUBJECTS Twenty-six PCa patients undergoing prostatectomy (mean age 59 years, range 46-72 years). FIELD STRENGTH/SEQUENCE Multiparametric MRI at 3.0T, including diffusion-weighted imaging (DWI) and LWI T2 mapping. ASSESSMENT LWI parameters and ADC were quantified in index PCa lesions and benign PZ. STATISTICAL TESTS Differences in MRI parameters between PCa and benign PZ were assessed using Wilcoxon signed tests. Spearman correlation of pathological grade group (GG) with LWI parameters, ADC, and PI-RADS was evaluated. The utility of each of the parameters for differentiation between low-grade (GG ≤2) and high-grade (GG ≥3) PCa was determined by Mann-Whitney U tests and ROC analyses. RESULTS Twenty-six index lesions were analyzed (mean size 1.7 ± 0.8 cm, GG: 1 [n = 1; 4%], 2 [n = 14, 54%], 3 [n = 8, 31%], 5 [n = 3, 12%]). LWI parameters and ADC both showed high diagnostic performance for differentiation between benign PZ and PCa (highest area under the curve [AUC] for LWI parameter T2,short [AUC = 0.98, P < 0.001]). The LWI parameters luminal water fraction (LWF) and amplitude of long T2 component Along significantly correlated with GG (r = -0.441, P = 0.024 and r = -0.414, P = 0.036, respectively), while PI-RADS, ADC, and the other LWI parameters did not (P = 0.132-0.869). LWF and Along also showed significant differences between low-grade and high-grade PCa (AUC = 0.776, P = 0.008 and AUC = 0.758, P = 0.027, respectively). Maximum diagnostic performance for discrimination of high-grade PCa was found with combined LWI parameters (AUC 0.891, P = 0.001). DATA CONCLUSION LWI parameters, in particular in combination, showed superior diagnostic performance for differentiation between low-grade and high-grade PCa compared to ADC and PI-RADS assessment. J. Magn. Reson. Imaging 2020;52:271-279.
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Affiliation(s)
- Stefanie J Hectors
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | - Daniela Said
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,Department of Radiology, Universidad de los Andes, Santiago, Chile
| | - Jeffrey Gnerre
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Ashutosh Tewari
- Department of Urology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Bachir Taouli
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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Cosma I, Tennstedt-Schenk C, Winzler S, Psychogios MN, Pfeil A, Teichgraeber U, Malich A, Papageorgiou I. The role of gadolinium in magnetic resonance imaging for early prostate cancer diagnosis: A diagnostic accuracy study. PLoS One 2019; 14:e0227031. [PMID: 31869380 PMCID: PMC6927639 DOI: 10.1371/journal.pone.0227031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 12/10/2019] [Indexed: 01/01/2023] Open
Abstract
Objective Prostate lesions detected with multiparametric magnetic resonance imaging (mpMRI) are classified for their malignant potential according to the Prostate Imaging-Reporting And Data System (PI-RADS™2). In this study, we evaluate the diagnostic accuracy of the mpMRI with and without gadolinium, with emphasis on the added diagnostic value of the dynamic contrast enhancement (DCE). Materials and methods The study was retrospective for 286 prostate lesions / 213 eligible patients, n = 116/170, and 49/59% malignant for the peripheral (Pz) and transitional zone (Tz), respectively. A stereotactic MRI-guided prostate biopsy served as the histological ground truth. All patients received a mpMRI with DCE. The influence of DCE in the prediction of malignancy was analyzed by blinded assessment of the imaging protocol without DCE and the DCE separately. Results Significant (CSPca) and insignificant (IPca) prostate cancers were evaluated separately to enhance the potential effects of the DCE in the detection of CSPca. The Receiver Operating Characteristics Area Under Curve (ROC-AUC), sensitivity (Se) and specificity (Spe) of PIRADS-without-DCE in the Pz was 0.70/0.47/0.86 for all cancers (IPca and CSPca merged) and 0.73/0.54/0.82 for CSPca. PIRADS-with-DCE for the same patients showed ROC-AUC/Se/Spe of 0.70/0.49/0.86 for all Pz cancers and 0.69/0.54/0.81 for CSPca in the Pz, respectively, p>0.05 chi-squared test. Similar results for the Tz, AUC/Se/Spe for PIRADS-without-DCE was 0.75/0.61/0.79 all cancers and 0.67/0.54/0.71 for CSPca, not influenced by DCE (0.66/0.47/0.81 for all Tz cancers and 0.61/0.39/0.75 for CSPca in Tz). The added Se and Spe of DCE for the detection of CSPca was 88/34% and 78/33% in the Pz and Tz, respectively. Conclusion DCE showed no significant added diagnostic value and lower specificity for the prediction of CSPca compared to the non-enhanced sequences. Our results support that gadolinium might be omitted without mitigating the diagnostic accuracy of the mpMRI for prostate cancer.
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Affiliation(s)
- Ilinca Cosma
- Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
- Institute of Radiology, Suedharz Hospital Nordhausen, Nordhausen, Germany
| | | | - Sven Winzler
- Institute of Radiology, Suedharz Hospital Nordhausen, Nordhausen, Germany
| | - Marios Nikos Psychogios
- Department of Neuroradiology, Clinic of Radiology and Nuclear Medicine, University Hospital Basel, Basel, Switzerland
| | - Alexander Pfeil
- Department of Internal Medicine, University Hospital Jena, Jena, Germany
| | - Ulf Teichgraeber
- Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Ansgar Malich
- Institute of Radiology, Suedharz Hospital Nordhausen, Nordhausen, Germany
| | - Ismini Papageorgiou
- Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
- Institute of Radiology, Suedharz Hospital Nordhausen, Nordhausen, Germany
- * E-mail:
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Evaluation of Dispersion MRI for Improved Prostate Cancer Diagnosis in a Multicenter Study. AJR Am J Roentgenol 2018; 211:W242-W251. [DOI: 10.2214/ajr.17.19215] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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7
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Liao D, Xie L, Han Y, Du S, Wang H, Zeng C, Li Y. Dynamic contrast-enhanced magnetic resonance imaging for differentiating osteomyelitis from acute neuropathic arthropathy in the complicated diabetic foot. Skeletal Radiol 2018; 47:1337-1347. [PMID: 29654348 DOI: 10.1007/s00256-018-2942-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 03/10/2018] [Accepted: 03/25/2018] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The main purpose of this study was to investigate the diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) in differentiating osteomyelitis from acute neuropathic arthropathy in the diabetic foot. MATERIALS AND METHODS This prospective study was carried out on 30 diabetic foot patients, with a mean age of 51 years. The patients all underwent clinical examinations, laboratory examinations and DCE-MRI. The DCE-MRI parameters (Ktrans, Kep and Ve) of the regions of acute neuropathic arthropathy and osteomyelitis were calculated. Receiver operating characteristic curves (ROCs) were used to identify the DCE-MRI parameters that showed the highest accuracy in differentiating the acute neuropathic arthropathy from the osteomyelitic regions. Pearson correlation coefficients were used to assess the correlations among the DCE-MRI parameters, the level of C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR). RESULTS The Ktrans, Kep and Ve values of the osteomyelitic regions were higher than those of the acute neuropathic arthropathy regions, and significant differences were found between the two groups (P = 0.000, P = 0.000, P = 0.000). The ROC analysis showed that Ktrans and Ve performed best in differentiating osteomyelitis from acute neuropathic arthropathy, both with an area under the curve of 0.938. The Pearson correlation coefficients showed that the DCE-MRI parameters correlated significantly with the level of CRP and ESR (P = 0.000, P = 0.014, P = 0.000; P = 0.000, P = 0.000, P = 0.013). CONCLUSIONS Our results showed that DCE-MRI may provide reproducible parameters that can reliably differentiate osteomyelitis from acute neuropathic arthropathy.
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Affiliation(s)
- Dan Liao
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Liqiu Xie
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Yongliang Han
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Silin Du
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Hansheng Wang
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Chun Zeng
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, China
| | - Yongmei Li
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, China.
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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.
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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.
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He D, Zamora M, Oto A, Karczmar GS, Fan X. Comparison of region-of-interest-averaged and pixel-averaged analysis of DCE-MRI data based on simulations and pre-clinical experiments. Phys Med Biol 2017; 62:N445-N459. [PMID: 28786402 DOI: 10.1088/1361-6560/aa84d6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Differences between region-of-interest (ROI) and pixel-by-pixel analysis of dynamic contrast enhanced (DCE) MRI data were investigated in this study with computer simulations and pre-clinical experiments. ROIs were simulated with 10, 50, 100, 200, 400, and 800 different pixels. For each pixel, a contrast agent concentration as a function of time, C(t), was calculated using the Tofts DCE-MRI model with randomly generated physiological parameters (K trans and v e) and the Parker population arterial input function. The average C(t) for each ROI was calculated and then K trans and v e for the ROI was extracted. The simulations were run 100 times for each ROI with new K trans and v e generated. In addition, white Gaussian noise was added to C(t) with 3, 6, and 12 dB signal-to-noise ratios to each C(t). For pre-clinical experiments, Copenhagen rats (n = 6) with implanted prostate tumors in the hind limb were used in this study. The DCE-MRI data were acquired with a temporal resolution of ~5 s in a 4.7 T animal scanner, before, during, and after a bolus injection (<5 s) of Gd-DTPA for a total imaging duration of ~10 min. K trans and v e were calculated in two ways: (i) by fitting C(t) for each pixel, and then averaging the pixel values over the entire ROI, and (ii) by averaging C(t) over the entire ROI, and then fitting averaged C(t) to extract K trans and v e. The simulation results showed that in heterogeneous ROIs, the pixel-by-pixel averaged K trans was ~25% to ~50% larger (p < 0.01) than the ROI-averaged K trans. At higher noise levels, the pixel-averaged K trans was greater than the 'true' K trans, but the ROI-averaged K trans was lower than the 'true' K trans. The ROI-averaged K trans was closer to the true K trans than pixel-averaged K trans for high noise levels. In pre-clinical experiments, the pixel-by-pixel averaged K trans was ~15% larger than the ROI-averaged K trans. Overall, with the Tofts model, the extracted physiological parameters from the pixel-by-pixel averages were larger than the ROI averages. These differences were dependent on the heterogeneity of the ROI.
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Affiliation(s)
- Dianning He
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, People's Republic of China. Department of Radiology, The University of Chicago, Chicago, IL 60637, United States of America
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