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Added Value of Assessing Adnexal Masses with Advanced MRI Techniques. BIOMED RESEARCH INTERNATIONAL 2015; 2015:785206. [PMID: 26413542 PMCID: PMC4564594 DOI: 10.1155/2015/785206] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 11/23/2014] [Accepted: 12/07/2014] [Indexed: 12/16/2022]
Abstract
This review will present the added value of perfusion and diffusion MR sequences to characterize adnexal masses. These two functional MR techniques are readily available in routine clinical practice. We will describe the acquisition parameters and a method of analysis to optimize their added value compared with conventional images. We will then propose a model of interpretation that combines the anatomical and morphological information from conventional MRI sequences with the functional information provided by perfusion and diffusion weighted sequences.
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Le Y, Dale B, Akisik F, Koons K, Lin C. Improved T1, contrast concentration, and pharmacokinetic parameter quantification in the presence of fat with two-point Dixon for dynamic contrast-enhanced magnetic resonance imaging. Magn Reson Med 2015; 75:1677-84. [PMID: 25988338 DOI: 10.1002/mrm.25639] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 01/06/2015] [Accepted: 01/07/2015] [Indexed: 11/06/2022]
Abstract
PURPOSE To evaluate the impact of fat and fat-suppression on the quantification of T1, gadolinium concentration, and pharmacokinetic parameters in DCE-MRI. METHODS T1 values were measured in fat-free phantoms using variable flip angle with no fat suppression, quick or interleaved fat saturation (QFS), or two-point Dixon and were compared with reference values measured with inversion recovery-prepared turbo spin echo. Relaxivity of gadolinium-benzyloxypropionictetraacetate (Gd-BOPTA) was measured in emulsions of Gd-BOPTA solution and fat using Dixon in-phase and water-only images. Liver T1 and pharmacokinetic parameters of 15 patients were calculated from Dixon in-phase and water-only images and were correlated with liver fat signal fraction. RESULTS T1 values measured using Dixon water-only and non-fat-suppressed images matched the reference values; while T1 values measured using QFS showed large deviations. Relaxivities and Gd measured in the Dixon water-only images were less affected by the fat than those measured in the in-phase images. The correlation between liver fat fraction and the differences in measured pharmacokinetic parameters using Dixon in-phase and water-only images were significant (P < 0.05) for T1, K(trans), and incremental area under the curve, but not Ve (P = 0.1). CONCLUSION Dixon water-only images provided more reliable estimation of T1, Gd, and pharmacokinetic parameters when fat was present.
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Affiliation(s)
- Yuan Le
- Department of Radiology and Imaging Science, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Brian Dale
- Siemens Medical Solutions, USA, MR R&D, Morrisville, North Carolina, USA
| | - Fatih Akisik
- Department of Radiology and Imaging Science, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Karen Koons
- Department of Radiology, Indiana University Health, Indianapolis, Indiana, USA
| | - Chen Lin
- Department of Radiology and Imaging Science, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Freed M, de Zwart JA, Hariharan P, Myers MR, Badano A. Development and characterization of a dynamic lesion phantom for the quantitative evaluation of dynamic contrast-enhanced MRI. Med Phys 2011; 38:5601-11. [PMID: 21992378 PMCID: PMC3195376 DOI: 10.1118/1.3633911] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/24/2011] [Accepted: 08/15/2011] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop a dynamic lesion phantom that is capable of producing physiological kinetic curves representative of those seen in human dynamic contrast-enhanced MRI (DCE-MRI) data. The objective of this phantom is to provide a platform for the quantitative comparison of DCE-MRI protocols to aid in the standardization and optimization of breast DCE-MRI. METHODS The dynamic lesion consists of a hollow, plastic mold with inlet and outlet tubes to allow flow of a contrast agent solution through the lesion over time. Border shape of the lesion can be controlled using the lesion mold production method. The configuration of the inlet and outlet tubes was determined using fluid transfer simulations. The total fluid flow rate was determined using x-ray images of the lesion for four different flow rates (0.25, 0.5, 1.0, and 1.5 ml/s) to evaluate the resultant kinetic curve shape and homogeneity of the contrast agent distribution in the dynamic lesion. High spatial and temporal resolution x-ray measurements were used to estimate the true kinetic curve behavior in the dynamic lesion for benign and malignant example curves. DCE-MRI example data were acquired of the dynamic phantom using a clinical protocol. RESULTS The optimal inlet and outlet tube configuration for the lesion molds was two inlet molds separated by 30° and a single outlet tube directly between the two inlet tubes. X-ray measurements indicated that 1.0 ml/s was an appropriate total fluid flow rate and provided truth for comparison with MRI data of kinetic curves representative of benign and malignant lesions. DCE-MRI data demonstrated the ability of the phantom to produce realistic kinetic curves. CONCLUSIONS The authors have constructed a dynamic lesion phantom, demonstrated its ability to produce physiological kinetic curves, and provided estimations of its true kinetic curve behavior. This lesion phantom provides a tool for the quantitative evaluation of DCE-MRI protocols, which may lead to improved discrimination of breast cancer lesions.
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Affiliation(s)
- Melanie Freed
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, USA.
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Pack NA, DiBella EVR. Comparison of myocardial perfusion estimates from dynamic contrast-enhanced magnetic resonance imaging with four quantitative analysis methods. Magn Reson Med 2010; 64:125-37. [PMID: 20577976 DOI: 10.1002/mrm.22282] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dynamic contrast-enhanced MRI has been used to quantify myocardial perfusion in recent years. Published results have varied widely, possibly depending on the method used to analyze the dynamic perfusion data. Here, four quantitative analysis methods (two-compartment modeling, Fermi function modeling, model-independent analysis, and Patlak plot analysis) were implemented and compared for quantifying myocardial perfusion. Dynamic contrast-enhanced MRI data were acquired in 20 human subjects at rest with low-dose (0.019 +/- 0.005 mmol/kg) bolus injections of gadolinium. Fourteen of these subjects were also imaged at adenosine stress (0.021 +/- 0.005 mmol/kg). Aggregate rest perfusion estimates were not significantly different between all four analysis methods. At stress, perfusion estimates were not significantly different between two-compartment modeling, model-independent analysis, and Patlak plot analysis. Stress estimates from the Fermi model were significantly higher (approximately 20%) than the other three methods. Myocardial perfusion reserve values were not significantly different between all four methods. Model-independent analysis resulted in the lowest model curve-fit errors. When more than just the first pass of data was analyzed, perfusion estimates from two-compartment modeling and model-independent analysis did not change significantly, unlike results from Fermi function modeling.
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Affiliation(s)
- Nathan A Pack
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
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Pack NA, DiBella EVR, Rust TC, Kadrmas DJ, McGann CJ, Butterfield R, Christian PE, Hoffman JM. Estimating myocardial perfusion from dynamic contrast-enhanced CMR with a model-independent deconvolution method. J Cardiovasc Magn Reson 2008; 10:52. [PMID: 19014509 PMCID: PMC2596132 DOI: 10.1186/1532-429x-10-52] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 11/12/2008] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Model-independent analysis with B-spline regularization has been used to quantify myocardial blood flow (perfusion) in dynamic contrast-enhanced cardiovascular magnetic resonance (CMR) studies. However, the model-independent approach has not been extensively evaluated to determine how the contrast-to-noise ratio between blood and tissue enhancement affects estimates of myocardial perfusion and the degree to which the regularization is dependent on the noise in the measured enhancement data. We investigated these questions with a model-independent analysis method that uses iterative minimization and a temporal smoothness regularizer. Perfusion estimates using this method were compared to results from dynamic 13N-ammonia PET. RESULTS An iterative model-independent analysis method was developed and tested to estimate regional and pixelwise myocardial perfusion in five normal subjects imaged with a saturation recovery turboFLASH sequence at 3 T CMR. Estimates of myocardial perfusion using model-independent analysis are dependent on the choice of the regularization weight parameter, which increases nonlinearly to handle large decreases in the contrast-to-noise ratio of the measured tissue enhancement data. Quantitative perfusion estimates in five subjects imaged with 3 T CMR were 1.1 +/- 0.8 ml/min/g at rest and 3.1 +/- 1.7 ml/min/g at adenosine stress. The perfusion estimates correlated with dynamic 13N-ammonia PET (y = 0.90x + 0.24, r = 0.85) and were similar to results from other validated CMR studies. CONCLUSION This work shows that a model-independent analysis method that uses iterative minimization and temporal regularization can be used to quantify myocardial perfusion with dynamic contrast-enhanced perfusion CMR. Results from this method are robust to choices in the regularization weight parameter over relatively large ranges in the contrast-to-noise ratio of the tissue enhancement data.
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Affiliation(s)
- Nathan A Pack
- Department of Bioengineering, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Edward VR DiBella
- Department of Bioengineering, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Thomas C Rust
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Dan J Kadrmas
- Department of Bioengineering, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Christopher J McGann
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Regan Butterfield
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - Paul E Christian
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
| | - John M Hoffman
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Salt Lake County, Utah, USA
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Planchamp C, Gex-Fabry M, Becker CD, Pastor CM. Model-based analysis of Gd-BOPTA-induced MR signal intensity changes in cirrhotic rat livers. Invest Radiol 2007; 42:513-21. [PMID: 17568274 DOI: 10.1097/rli.0b013e318036b450] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE To quantify the hepatic transport of the hepatobiliary contrast agent gadobenate dimeglumine (Gd-BOPTA) in rats with biliary cirrhosis of various severity degrees from magnetic resonance (MR) signal intensities using a population pharmacokinetic approach. MATERIALS AND METHODS MR signal intensity was recorded during the Gd-BOPTA perfusion of normal and cirrhotic isolated rat livers. Similar experiments were conducted with Gd-labeled Gd-BOPTA to quantify Gd-BOPTA content in liver, bile, and perfusate. All experimental data were analyzed together according to a population pharmacokinetic approach. RESULTS A 6-compartment model developed from the radioactivity data adequately fit all MRI data when 4 image parameters were added to describe the relationship between the amount of contrast agent and the signal intensity. The model showed that entry of Gd-BOPTA into hepatocytes was decreased in cirrhotic livers when compared to normal livers. CONCLUSIONS Although the MR signal intensity is similar in normal and cirrhotic livers, the population pharmacokinetic approach developed in this study shows a decreased entry of Gd-BOPTA into cirrhotic hepatocytes.
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Affiliation(s)
- Corinne Planchamp
- Laboratoire de Physiopathologie Hépatique et Imagerie Moléculaire, and Département de Psychiatrie, Hôpitaux Universitaires de Genève, Geneva, Switzerland
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Makkat S, Luypaert R, Sourbron S, Stadnik T, De Mey J. Quantification of perfusion and permeability in breast tumors with a deconvolution-based analysis of second-bolus T1-DCE data. J Magn Reson Imaging 2007; 25:1159-67. [PMID: 17520720 DOI: 10.1002/jmri.20937] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To test the feasibility of using a second-bolus injection, added to a routine breast MRI examination, to measure regional perfusion and permeability in human breast tumors. MATERIALS AND METHODS In 30 patients with breast tumors, first a routine whole-breast T1-DCE sequence was applied, and the slice where the lesion enhanced maximally was located. At that slice position, T1-weighted MR images were acquired at 0.3-second resolution using a second-bolus dynamic inversion recovery (IR)-prepared turbo field echo (TFE) sequence. A pixel-by-pixel model-independent deconvolution of the relative signal enhancement was performed to estimate the tumor blood flow (TBF), tumor volume of distribution (TVD), mean transit time (MTT), extraction flow product (EF), and extraction fraction (E). In addition to this pilot study, a first appraisal of its sensitivity to tissue type was made on the basis of a small patient cohort. RESULTS In the malignant tumors, the parametric maps clearly delineated tumors from the breast tissue and enabled visualization of the heterogeneity. The deconvolution analysis provided objective parametric maps of tumor perfusion with a mean TBF (84 +/- 48 mL/100 mL/minute) in malignant tumors in the high range of literature values. CONCLUSION In terms of these perfusion values, our method appears promising to quantitatively characterize tumor pathophysiology. However, the number of patients was limited, and the separation between malignant and benign groups was not clear-cut. Additional parameters generated through compartment modeling may improve the tumor differentiation.
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Affiliation(s)
- S Makkat
- Department of Radiology, Academisch Ziekenhuis Vrije Universiteit Brussel/Medische Beeldvorming en Fysische Wetenschappen (BEFY), Laarbeeklaan 101, 1090 Brussels, Belgium.
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Planchamp C, Pastor CM, Balant L, Becker CD, Terrier F, Gex-Fabry M. Quantification of Gd-BOPTA uptake and biliary excretion from dynamic magnetic resonance imaging in rat livers: model validation with 153Gd-BOPTA. Invest Radiol 2006; 40:705-14. [PMID: 16230903 DOI: 10.1097/01.rli.0000183053.08921.2b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVES We sought to develop and validate a pharmacokinetic model allowing description of the magnetic resonance (MR) signal intensity induced by the hepatobiliary contrast agent Gd-BOPTA and to quantify the overall Gd-BOPTA transport in rat liver. MATERIALS AND METHODS MR signal intensity was recorded during the perfusion of rat livers with Gd-DTPA, an extracellular contrast agent, and Gd-BOPTA, a hepatobiliary contrast agent. Similar experiments were conducted with Gd-labeled contrast agents for quantitative measurement in liver, bile and perfusate. RESULTS A complete 6-compartment, 8 parameter open model was first developed to describe the pharmacokinetics of the compound based on the radioactivity data analysis. Because perfusate and bile data were not available in MRI experiments, a reduced model (6-compartment, 5 parameters) was considered for the MRI data. The performance of the reduced model was tested using the radioactivity data. The reduced model successfully described the contrast agent amount in the liver and correctly predicted amounts in bile and perfusate. CONCLUSIONS Pharmacokinetic modeling of MR signal intensity induced by Gd-BOPTA permits quantification of Gd-BOPTA uptake and biliary excretion in rat livers.
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Affiliation(s)
- Corinne Planchamp
- Department of Radiology, Geneva University Hospitals, Geneva, Switzerland.
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Michoux N, Montet X, Pechère A, Ivancevic MK, Martin PY, Keller A, Didier D, Terrier F, Vallée JP. Parametric and quantitative analysis of MR renographic curves for assessing the functional behaviour of the kidney. Eur J Radiol 2005; 54:124-35. [PMID: 15797302 DOI: 10.1016/j.ejrad.2004.04.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2004] [Revised: 04/08/2004] [Accepted: 04/13/2004] [Indexed: 11/24/2022]
Abstract
The aim of this study was to refine the description of the renal function based on MR images and through transit-time curve analysis on a normal population and on a population with renal failure, using the quantitative model of the up-slope. Thirty patients referred for a kidney MR exam were divided in a first population with well-functioning kidneys and in a second population with renal failure from ischaemic kidney disease. The perfusion sequence consisted of an intravenous injection of Gd-DTPA and of a fast GRE sequence T1-TFE with 90 degrees magnetisation preparation (Intera 1.5 T MR System, Philips Medical System). To convert the signal intensity into 1/T1, which is proportional to the contrast media concentration, a flow-corrected calibration procedure was used. Following segmentation of regions of interest in the cortex and medulla of the kidney and in the abdominal aorta, outflow curves were obtained and filtered to remove the high frequency fluctuations. The model of the up-slope method was then applied. Significant reduction of the cortical perfusion (Qc = 0.057+/-0.030 ml/(s 100 g) to Qc = 0.030 +/- 0.017 ml/(s 100 g), P < 0.013) of the medullary perfusion (Qm = 0.023 +/- 0.018 ml/(s 100 g) to Qm = 0.011 +/- 0.006 ml/(s 100 g), P < 0.046) and of the accumulation of contrast media in the medulla (Qa = 0.005 +/- 0.003 ml/(s 100 g) to Qa = 0.0009 +/- 0.0008 ml/(s 100 g), P < 0.001) were found in presence of renal failure. High correlations were found between the creatinine level and the accumulation Qa in the medulla (r2 = 0.72, P < 0.05), and between the perfusion ratio Qc/Qm and the accumulation Qa in the medulla (r2 = 0.81, P < 0.05). No significant difference was found in times to peak between both populations despite a trend showing Ta the time to the end of the increasing contrast accumulation period in the medulla, arriving later for renal failure. Advances in MR signal calibration with the building of quantitative model such as the up-slope allow to assess kinetic and haemodynamic and functional parameters of the diseased kidney.
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Affiliation(s)
- N Michoux
- Unité d'imagerie Numérique, Département de Radiologie, Hôpital Universitaire de Genève, Rue Micheli-du-Crest 24, CH-1211 Geneva 14, Switzerland.
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Dujardin M, Sourbron S, Luypaert R, Verbeelen D, Stadnik T. Quantification of renal perfusion and function on a voxel-by-voxel basis: A feasibility study. Magn Reson Med 2005; 54:841-9. [DOI: 10.1002/mrm.20608] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Planchamp C, Gex-Fabry M, Dornier C, Quadri R, Reist M, Ivancevic MK, Vallée JP, Pochon S, Terrier F, Balant L, Stieger B, Meier PJ, Pastor CM. Gd-BOPTA Transport Into Rat Hepatocytes: Pharmacokinetic Analysis of Dynamic Magnetic Resonance Images Using a Hollow-Fiber Bioreactor. Invest Radiol 2004; 39:506-15. [PMID: 15257212 DOI: 10.1097/01.rli.0000129156.16054.30] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
RATIONALE AND OBJECTIVES To investigate the transport of the hepatobiliary magnetic resonance (MR) imaging contrast agent Gd-BOPTA into rat hepatocytes. MATERIALS AND METHODS In a MR-compatible hollow-fiber bioreactor containing hepatocytes, MR signal intensity was measured over time during the perfusion of Gd-BOPTA. For comparison, the perfusion of an extracellular contrast agent (Gd-DTPA) was also studied. A compartmental pharmacokinetic model was developed to describe dynamic signal intensity-time curves. RESULTS The dynamic signal intensity-time curves of the hepatocyte hollow-fiber bioreactor during Gd-BOPTA perfusion were adequately fitted by 2 compartmental models. Modeling permitted to discriminate between the behaviors of the extracellular contrast agent (Gd-DTPA) and the hepatobiliary contrast agent (Gd-BOPTA). It allowed the successfully quantification of the parameters involved in such differences. Gd-BOPTA uptake was saturable at high substrate concentrations. CONCLUSIONS The transport of Gd-BOPTA into rat hepatocytes was successfully described by compartmental analysis of the signal intensity recorded over time and supported the hypothesis of a transporter-mediated uptake.
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Affiliation(s)
- Corinne Planchamp
- Geneva University Hospitals, Radiology Department, Geneva, Switzerland.
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Planchamp C, Ivancevic MK, Pastor CM, Vallée JP, Pochon S, Terrier F, Mayer JM, Reist M. Hollow fiber bioreactor: New development for the study of contrast agent transport into hepatocytes by magnetic resonance imaging. Biotechnol Bioeng 2004; 85:656-65. [PMID: 14966807 DOI: 10.1002/bit.20017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The aim of our study was to develop a magnetic resonance (MR)-compatible in vitro model containing freshly isolated rat hepatocytes to study the transport of hepatobiliary contrast agents (CA) by MR imaging (MRI). We set up a perfusion system including a perfusion circuit, a heating device, an oxygenator, and a hollow fiber bioreactor (HFB). The role of the porosity and surface of the hollow fiber (HF) as well as the perfusate flow rate applied on the diffusion of CAs and O2 was determined. Hepatocytes were isolated and injected in the extracapillary space of the HFB (4 x 10(7) cells/mL). The hepatocyte HFB was perfused with an extracellular CA, gadopentetate dimeglumine (Gd-DTPA), and gadobenate dimeglumine (Gd-BOPTA), which also enters into hepatocytes. The HFB was imaged in the MR room using a dynamic T1-weighed sequence. No adsorption of CAs was detected in the perfusion system without hepatocytes. The use of a membrane with a high porosity (0.5 microm) and surface (420 cm2), and a high flow rate perfusion (100 mL/min) resulted in a rapid filling of the HFB with CAs. The cellular viability of hepatocytes in the HFB was greater than 85% and the O2 consumption was maintained over the experimental period. The kinetics of MR signal intensity (SI) clearly showed the different behavior of Gd-BOPTA that enters into hepatocytes and Gd-DTPA that remains extracellular. Thus, these results show that our newly developed in vitro model is an interesting tool to investigate the transport kinetics of hepatobiliary CAs by measuring the MR SI over time.
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Affiliation(s)
- Corinne Planchamp
- Geneva University Hospital, Radiology Department, Micheli-du-Crest 24, CH-1211 Geneva 14, Switzerland.
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Perrin RL, Ivancevic MK, Kozerke S, Vallee JP. Comparative study of FAST gradient echo MRI sequences: Phantom study. J Magn Reson Imaging 2004; 20:1030-8. [PMID: 15558562 DOI: 10.1002/jmri.20205] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
PURPOSE To investigate a balanced steady state free precession sequence (b-SSFP) under a large range of conditions and to compare its performance with other types of gradient echo sequences for dynamic imaging. MATERIALS AND METHODS Balanced turbo field echo (b-TFE; Philips Medical Systems, Best, The Netherlands) was investigated in vitro at a range of T2/T1 along with T1-contrast enhanced turbo field echo (T1-TFE) and turbo field echo (TFE) so that a comparison could be made. Performance was quantified in terms of the initial slope of the signal-to-noise ratio (SNR) vs. 1/T1 curve (sensitivity) and the range of 1/T1 before signal saturation (contrast dynamic range [CDR]). RESULTS The b-TFE sequence was found to best perform, in terms of an optimal CDR, with a 90 degrees flip angle (FA), saturation preparation, and short inversion time. Using these parameters, the sensitivity was also higher than that of the TFE sequence and T1-TFE sequence under their respective optimal conditions. For detection of small changes in contrast agent concentration (0.0-0.1 mM), b-TFE was also found to be the sequence of choice, with optimized parameters as follows, 90 degrees FA, shortest TR/TE, and no magnetization preparation. The smallest matrices gave the highest signal sensitivity for all three sequences. CONCLUSION The CDR of b-TFE was much narrower than that of T1-TFE but could be widened under optimized conditions. The sensitivity of the b-TFE technique was the highest of the three sequences under all conditions tested.
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Affiliation(s)
- Rosalind L Perrin
- Radiology Department, University Hospital of Geneva, Genève, Switzerland
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Ivancevic MK, Zimine I, Montet X, Hyacinthe JN, Lazeyras F, Foxall D, Vallée JP. Inflow effect correction in fast gradient-echo perfusion imaging. Magn Reson Med 2003; 50:885-91. [PMID: 14586998 DOI: 10.1002/mrm.10633] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The purposes of this study were to assess the extent of the inflow effect on signal intensity (SI) for fast gradient-recalled-echo (GRE) sequences used to observe first-pass perfusion, and to develop and validate a correction method for this effect. A phantom experiment with a flow apparatus was performed to determine SI as a function of Gd-DTPA concentration for various velocities. Subsequently a flow-sensitive calibration method was developed, and validated on bolus injections into an open-circuit flow apparatus and in vivo. It is shown that calibration methods based on static phantoms are not appropriate for accurate signal-to-concentration conversion in images affected by high flow. The flow-corrected calibration method presented here can be used to improve the accuracy and robustness of the arterial input function (AIF) determination for tissue perfusion quantification using MRI and contrast media.
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Affiliation(s)
- Marko K Ivancevic
- UIN, Department of Radiology, Geneva University Hospital, Geneva, Switzerland.
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Montet X, Ivancevic MK, Belenger J, Jorge-Costa M, Pochon S, Pechère A, Terrier F, Vallée JP. Noninvasive measurement of absolute renal perfusion by contrast medium-enhanced magnetic resonance imaging. Invest Radiol 2003; 38:584-92. [PMID: 12960528 DOI: 10.1097/01.rli.0000077127.11949.8c] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim of this study was to validate the quantification of absolute renal perfusion (RP) determined by dynamic magnetic resonance imaging (MRI) and contrast media using an experimental model in the rabbit and a transit-timed ultrasound flow probe around the left renal artery as comparison. MATERIAL AND METHODS An MR-compatible ultrasonic time-of-flight flow-probe was placed around the left renal artery in 9 New Zealand white rabbits. Absolute RP in basal state, after mechanical renal artery stenosis, intravenous dopamine, angiotensin II, or colloid infusion was measured using dynamic MRI and intravenous injection of gadoteridol. The results were correlated to the renal artery flow measured inside the magnet with the transit-timed flow-probe. For the signal intensity concentration conversion, we applied different calibrations according to various velocities measured in the aorta by a phase contrast sequence to correct for inflow effect. MRI-derived RP (in mL/min) was calculated by the maximum upslope method, where RP/volume was defined as the ratio of the cortex contrast enhancement slope over the maximum of the arterial input function determined in the aorta. RESULTS Reproducible arterial and renal transit curve with excellent contrast to noise ratio were obtained. The MRI derived perfusion was systematically underestimated by comparison to the ultrasonic transit-timed flow-probe but was linearly correlated with these measures (r = 0.80, P < 0.001). CONCLUSIONS Using a flow-sensitive calibration, an accurate arterial input function can be measured from the blood MR signal and used in a realistic model to assess the RP. There was a good correlation between the MR-derived RP and the renal artery blood flow measured by the flow-meter. This experimental study validates absolute RP quantification by MRI and contrast media injection and justifies further clinical studies.
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Affiliation(s)
- Xavier Montet
- Département de Radiologie, Unité d'imagerie numérique, Hôpital Universitaire de Genève, 24 Micheli-du-Crest, CH-1211 Geneva 14, Switzerland.
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Ivancevic MK, Zimine I, Foxall D, Lecoq G, Righetti A, Didier D, Vallée JP. Inflow effect in first-pass cardiac and renal MRI. J Magn Reson Imaging 2003; 18:372-6. [PMID: 12938136 DOI: 10.1002/jmri.10363] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To estimate the effect of the inflow effect on the arterial input function in vivo in cardiac and renal MR perfusion imaging using fast gradient echo (GRE) sequences and contrast media. MATERIALS AND METHODS The MR exam protocol was designed to acquire images at different phases of the cardiac cycle. The arterial input was thus influenced by various blood flow velocities. RESULTS It was found that the inflow effect was negligible in the left ventricle of the heart, while it was significantly higher in the aorta for the kidney perfusion measurement. This was principally due to the higher through-the-plane component of the blood flow velocity in the aorta than in the left ventricle. CONCLUSION The inflow effect can be neglected in the heart cavity, but should be taken into account in renal perfusion.
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Affiliation(s)
- Marko K Ivancevic
- Radiology Department, Geneva University Hospital, Geneva, Switzerland.
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