FAST sequences optimization for contrast media pharmacokinetic quantification in tissue

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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“…26 A linear relationship was found between concentrations and signal up to 0.5 mM. The r 1 relaxivity was 4.1 mM Ϫ1 s Ϫ1 .…”

Section: Mrimentioning

confidence: 84%

Gd-BOPTA Transport Into Rat Hepatocytes: Pharmacokinetic Analysis of Dynamic Magnetic Resonance Images Using a Hollow-Fiber Bioreactor

Planchamp

Gex‐Fabry²,

Dornier³

et al. 2004

Investigative Radiology

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“…Higher flip angles are recommended in Ref. (9) as a method to optimize the response to the changes in T 1 induced by typical contrast concentrations. Prior to our study we simulated the IRprepared FLASH signal (8) for a relevant range of T 1 values ( Fig.…”

Section: Mri Proceduresmentioning

confidence: 99%

Quantification of renal perfusion and function on a voxel‐by‐voxel basis: A feasibility study

Dujardin

Sourbron

Luypaert

et al. 2005

Magnetic Resonance in Med

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The feasibility of a voxel-by-voxel deconvolution analysis of T 1 -weighted DCE data in the human kidney and its potential for obtaining quantification of perfusion and filtration was investigated. Measurements were performed on 14 normal humans and 1 transplant at 1.5 T using a Turboflash sequence. Signal time-courses were converted to tracer concentrations and deconvolved with an aorta AIF. Parametric maps of relative renal blood flow (rRBF), relative renal volume of distribution (rRVD), relative mean transit time (rMTT), and whole cortex extraction fraction (E) were obtained from the impulse response functions. For the normals average cortical rRBF, rRVD, rMTT, and E were 1.6 mL/min/mL (SD 0.8), 0.4 mL/mL (SD 0.1), 17s (SD 7), and 22.6% (SD 6.1), respectively. A gradual voxelwise rRBF increase is found from the center of two infarction zones toward the edges. Voxel IRFs showed more detail on the nefron substructure than ROI IRFs. In conclusion, quantitative voxelwise perfusion mapping based on deconvolved T 1 -DCE renal data is feasible, but absolute quantification requires inflow correction. rRBF maps and quantitative values are sufficiently sensitive to detect perfusion abnormality in pathologic areas, but further research is necessary to separate perfusion from extraction and to characterize the different compartments of the nephron on the ( Key words: renal; T-weighted; perfusion; deconvolution; quantificationDynamic contrast enhanced MRI is a promising noninvasive method for imaging renal perfusion and function (1-5), since it avoids the use of ionizing radiation and combines high temporal and spatial resolution. Moreover, Gd-DTPA is very well tolerated, not nephrotoxic, and has properties comparable to the radioisotopic 99mTc-DTPA (6,7). Tissue perfusion imaging with dynamic Gd-DTPA enhanced MRI therefore offers the potential for obtaining important information about organ viability, anatomy, and function in the normal as well as in the compromised kidney.Experiments with a rabbit model (1) have shown that Gd-DTPA enhanced bolus tracking and a deconvolution analysis of ROI signals permit quantitative measures of perfusion and filtration, independent of the effect of the shape and size of the bolus. On the other hand, results obtained with an intravascular contrast agent have shown that a pixel-by-pixel approach to perfusion quantification can be a useful tool for distinguishing normality from renal artery stenosis in dogs as well as humans (2,3).In this study we investigate the combination of both approaches: a pixel-by-pixel deconvolution analysis in the human kidney, using Gd-DTPA enhanced bolus tracking. We investigate the quality of the resulting parametric maps, evaluate to what extent they represent perfusion and extraction, and assess the potential of the technique for obtaining reliable quantification of renal blood flow and a measure of filtration. We also investigate the possibility of obtaining other parameters like the tracers' volume of distribution and mean transit time. Our first results...

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“…We used a FAST sequence because it has a high signal intensity sensitivity for the low contrast agent concentrations used in this study. 42,43 However, with this sequence, the range of contrast agent amount along which the signal intensity linearly increases is short and signal intensity rapidly saturates. This is the reason why an equation of saturation was integrated in the model.…”

Section: Discussionmentioning

confidence: 98%

Quantification of Gd-BOPTA Uptake and Biliary Excretion From Dynamic Magnetic Resonance Imaging in Rat Livers

Planchamp¹,

Pastor²,

Balant³

et al. 2005

Investigative Radiology

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FAST sequences optimization for contrast media pharmacokinetic quantification in tissue

Cited by 17 publications

References 19 publications

Gd-BOPTA Transport Into Rat Hepatocytes: Pharmacokinetic Analysis of Dynamic Magnetic Resonance Images Using a Hollow-Fiber Bioreactor

Gd-BOPTA Transport Into Rat Hepatocytes: Pharmacokinetic Analysis of Dynamic Magnetic Resonance Images Using a Hollow-Fiber Bioreactor

Quantification of renal perfusion and function on a voxel‐by‐voxel basis: A feasibility study

Quantification of Gd-BOPTA Uptake and Biliary Excretion From Dynamic Magnetic Resonance Imaging in Rat Livers

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