Article

Detection threshold of single SPIO-labeled cells with FIESTA

Imaging Research Laboratories, Robarts Research Institute, London, Canada.
Magnetic Resonance in Medicine (Impact Factor: 3.4). 02/2005; 53(2):312-20. DOI: 10.1002/mrm.20356
Source: PubMed

ABSTRACT MRI of superparamagnetic iron oxide (SPIO)-labeled cells has become a valuable tool for studying the in vivo trafficking of transplanted cells. Cellular detection with MRI is generally considered to be orders of magnitude less sensitive than other techniques, such as positron emission tomography (PET), single photon emission-computed tomography (SPECT), or optical fluorescence microscopy. However, an analytic description of the detection threshold for single SPIO-labeled cells and the parameters that govern detection has not been adequately provided. In the present work, the detection threshold for single SPIO-labeled cells and the effect of resolution and SNR were studied for a balanced steady-state free precession (SSFP) sequence (3D-FIESTA). Based on the results from both theoretical and experimental analyses, an expression that predicts the minimum detectable mass of SPIO (m(c)) required to detect a single cell against a uniform signal background was derived: m(c) = 5v/(K(fsl) x SNR), where v is the voxel volume, SNR is the image signal-to-noise ratio, and K(fsl) is an empirical constant measured to be 6.2 +/- 0.5 x 10(-5) microl/pgFe. Using this expression, it was shown that the sensitivity of MRI is not very different from that of PET, requiring femtomole quantities of SPIO iron for detection under typical micro-imaging conditions (100 microm isotropic resolution, SNR = 60). The results of this work will aid in the design of cellular imaging experiments by defining the lower limit of SPIO labeling required for single cell detection at any given resolution and SNR.

Download full-text

Full-text

Available from: Chris V Bowen, Apr 15, 2014
0 Followers
 · 
100 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: With the advance of stem cell transplantation research, in vivo cell tracking techniques have become increasingly important in recent years. Magnetic resonance imaging (MRI) may provide a unique tool for non-invasive tracking of transplanted cells. Since the initial findings on the stem cell migration by MRI several years ago, there have been numerous studies using various animal models, notably in heart or brain disease models. In order to develop more reliable and clinically applicable methodologies, multiple aspects should be taken into consideration. In this review, we will summarize the current status and future perspectives of in vivo cell tracking technologies using MRI. In particular, use of different MR contrast agents and their detection methods using MRI will be described in much detail. In addition, various cell labeling methods to increase the sensitivity of signals will be extensively discussed. We will also review several key experiments, in which MRI techniques were utilized to detect the presence and/or migration of transplanted stem cells in various animal models. Finally, we will discuss the current problems and future directions of cell tracking methods using MRI.
    Molecules and Cells 05/2007; 23(2):132-7. · 2.24 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the sensitivity and specificity of MR acquisition methods for molecular imaging, we extended a magnetic resonance imaging (MRI) simulator. This simulator is capable of complete modeling of object (tissue) in microscopic level to study the effect of spatial distribution and concentration of nanoparticles. Using this tool we studied gradient-echo (GE), and True-FISP pulse sequences. In terms of detection sensitivity, GE and True-FISP detected individual labeled cells in 9.4 T MRI. We then conducted a systematic study in order to determine the optimal parameters for GE and True-FISP pulse sequences (echo time, repetition time, iron mass per cell, and image resolution). This simulation study provides a basis for planning experiments aimed at single cell detection with GE and True-FISP sequences.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Proton magnetic resonance spectroscopy was used at 3T to measure the uptake and clearance of brain ethanol in rats after bolus intraperitoneal (i.p.) or intragastric (i.g.) alcohol injection, and to estimate the effects of acute alcohol on brain metabolites. The observation duration was 1-1.5 h with temporal resolution of alcohol sampling ranging from 4 s-4 min. The observed time course of alcohol brain concentration followed a consistent pattern characterized by a rapid absorption, an intermediate distribution, and a slower clearance that approached a linear decay. In a sample of eight healthy Wistar rats, the intercept of the linear clearance term, extrapolated back to the time of injection, correlated well with the administered dose per unit of lean body mass. Alcohol concentration estimation based on spectroscopically measured clearance was compared with blood alcohol levels from blood samples at the end of observation, and were in good agreement with the administered dose. Serial proton spectroscopy measurements provide a valid in vivo method for quantifying brain alcohol uptake and elimination kinetics in real time.
    Neuropsychopharmacology 01/2007; 31(12):2683-91. DOI:10.1038/sj.npp.1301023 · 7.83 Impact Factor