Document Type: Original Research


PhD, Associated Professor of Medical Physics, Department of Biomedical Engineering, Faculty of Health, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran


Background: The relationship between the concentration of contrast agents and signal intensity (SI) are affected by some image parameters, phase-encoding scheme, magnetic field strength, image sequences, and iron oxide nanoparticles used and Gd-DTPA as MRI contrast agents.
Objective: In this article, the effect of saturation times (TSs) on the maximum and minimum SI, and also the linear relationship between the concentration of the contrast agent and SI are evaluated. Additionally, we evaluated the concentration of contrast agent that results the minimum SI using a saturation recovery TurboFLASH sequence.
Material and Methods: In this experimental study, a phantom was designed to hold vials with different concentrations of Gd-DTPA (0–19.77mmol/L). The mean SI was acquired from the nine central pixels of every vial at various TSs.
Results: This study shows that the maximum SI in an image is dependent on short TSs (up to 400ms) and independent of long TSs (400–1000ms). The result also shows that the concentration at which a maximum linear relationship between concentration and SI is maintained that gave an R2 equal to 0.95 and 0.99 dependent on the TS. Moreover, the outcome demonstrates that as TS increases, the concentration of the contrast agent decreases. This causes SI to be minimized.
Conclusion: This study demonstrated that the TS is a key parameter for measuring the maximum and minimum SI and also TS plays the role in determining the maximum linear relationship between the MRI contrast agent concentration and SI in an in vivo perfusion study.


  1. Calamante F, Vonken EJ, Van Osch MJ. Contrast agent concentration measurements affecting quantification of bolus-tracking perfusion MRI. Magn Reson Med. 2007;58:544-53. doi: 10.1002/mrm.21362. PubMed PMID: 17763347.
  2. Gharehaghaji N, Nazarpoor M, Saharkhiz H. Effect of iron oxide nanoparticles coating type on the relationship between nanoparticles concentration and signal intensity in inversion recovery T1-weighted MRI. Med J Islam Repub Iran. 2015;29:211-20. doi: 10.5812/iranjradiol.22887.
  3. Rohrer M, Bauer H, Mintorovitch J, Requardt M, Weinmann HJ. Comparison of magnetic properties of MRI contrast media solutions at different magnetic field strengths. Invest Radiol. 2005;40:715-24. doi: 10.1097/01.rli.0000184756.66360.d3. PubMed PMID: 16230904.
  4. Nazarpoor M, Mayabi Z, Shfaie A, Pesianian E, Aghaverdizadeh D. Maximum relationship between signal intensity and concentration of contrast agent in 0.3 T and 1.5 T using T1-weighted spin echo sequence. Medical Journal of Tabriz University of Medical Sciences & Health services. 2011;32:72-6.
  5. Nazarpoor M, Poureisa M, Daghighi MH. Comparison of maximum signal intensity of contrast agent on t1-weighted images using spin echo, fast spin echo and inversion recovery sequences. Iran J Radiol. 2012;10:27-32. doi: 10.5812/iranjradiol.5452. PubMed PMID: 23599710. PubMed PMCID: PMC3618902.
  6. Bernstein MA, King KF, Zhou XJ. Handbook of MRI pulse sequences. London: Elsevier; 2004.
  7. Nazarpoor M. Effect of phase-encoding scheme on the relationship between contrast agent concentration and signal intensity on inversion recovery Turbo Fast Low-Angle Shot T1-weighted images. Radiological physics and technology. 2014;7:262-70. doi: 10.1007/s12194-014-0260-7.
  8. Nazarpoor M. Organ Blood Flow Measurement with T1 and T2*-Weighted MRI Techniques. Saarbrücken: Lap Lambert Academic Publ; 2012.
  9. Lüdemann L, Warmuth C, Plotkin M, Förschler A, Gutberlet M, Wust P, et al. Brain tumor perfusion: Comparison of dynamic contrast enhanced magnetic resonance imaging using T1, T2, and T2* contrast, pulsed arterial spin labeling, and H215O positron emission tomography. Eur J Radiol. 2009;70:465-74. doi: 10.1016/j.ejrad.2008.02.012.
  10. Nazarpoor M. Effect of concentration of contrast agent on the inflow effect for measuring absolute perfusion by use of inversion recovery T 1-weighted TurboFLASH images. Radiological physics and technology. 2012;5:86-91.
  11. Canet E, Douek P, Janier M, Bendid K, Amaya J, Millet P, et al. Influence of bolus volume and dose of gadolinium chelate for first-pass myocardial perfusion MR imaging studies. J Magn Reson Imaging. 1995;5:411-5. doi: 10.1002/jmri.1880050407. PubMed PMID: 7549202.
  12. Takeda M, Katayama Y, Tsutsui T, Komeyama T, Mizusawa T. Does gadolinium-diethylene triamine pentaacetic acid enhanced MRI of kidney represent tissue concentration of contrast media in the kidney? in vivo and in vitro study. Magn Reson Imaging. 1994;12:421-7. doi: 10.1016/0730-725x(94)92535-6.
  13. Fritz-Hansen T, Rostrup E, Ring PB, Larsson HB. Quantification of gadolinium-DTPA concentrations for different inversion times using an IR-turbo flash pulse sequence: a study on optimizing multislice perfusion imaging. Magn Reson Imaging. 1998;16:893-9. doi: 10.1016/s0730-725x(98)00103-9. PubMed PMID: 9814771.
  14. Morkenborg J, Pedersen M, Jensen FT, Stodkilde-Jorgensen H, Djurhuus JC, Frokiaer J. Quantitative assessment of Gd-DTPA contrast agent from signal enhancement: an in-vitro study. Magn Reson Imaging. 2003;21:637-43. doi: 10.1016/s0730-725x(03)00096-1. PubMed PMID: 12915195.
  15. Dean BL, Lee C, Kirsch JE, Runge VM, Dempsey RM, Pettigrew LC. Cerebral hemodynamics and cerebral blood volume: MR assessment using gadolinium contrast agents and T1-weighted Turbo-FLASH imaging. American journal of neuroradiology. 1992;13:39-48.
  16. Unger EC, Ugurbil K, Latchaw RE. Contrast agents for cerebral perfusion MR imaging. J Magn Reson Imaging. 1994;4:235-42. doi: 10.1002/jmri.1880040303. PubMed PMID: 8061420.
  17. Nazarpoor M. The effect of repetition time on the maximum linear relationship between contrast agent concentration and signal intensity on T1-weighted image using inversion recovery (IR) sequence. Iranian Journal of Radiology. 2009;6(4):247-52.
  18. Nazarpoor M. Effects of inversion and saturation times on relationships between contrast agent concentrations and signal intensities of T 1-weighted magnetic resonance images. Radiological physics and technology. 2010;3:120-6. doi: 10.1007/s12194-010-0087-9.
  19. Nazarpoor M, Gharehaghaji N, Saharkhiz H. Effect of Inversion Time on the Linear Correlation between Polyethylene Glycol Coated Iron Oxide Nanoparticles Concentration and Signal Intensity in Inversion Recovery MRI Pulse Sequence. Journal of Mazandaran University of Medical Sciences. 2015;24:88-97.
  20. Nazarpoor M, Poureisa M, Daghighi MH. Effect of echo time on the maximum relationship between contrast agent concentration and signal intensity using FLAIR sequence. Iranian Journal of Medical Physics. 2013;10:59-67.
  21. Gharehaghaji N, Nazarpoor M, Saharkhiz H. Effect of Flip Angle on the Correlation Between Signal Intensity and Different Concentrations of Iron Oxide Nanoparticles Using T1-Weighted Turbo-FLASH Inversion Recovery Sequence. Iran J Radiol. 2015;12:e22887. doi: 10.5812/iranjradiol.22887. PubMed PMID: 25901260. PubMed PMCID: PMC4389174.
  22. McRobbie DW, Moore EA, Graves MJ, Prince MR. MRI: Prom Picture to Proton. UK, Cambridge: Cambridge University Press; 2006.
  23. Nazarpoor M. Non-uniformity of Clinical Head, Head and Neck, and Body Coils in Magnetic Resonance Imaging (MRI). Iranian Journal of Medical Physics. 2014;11:322-7.
  24. Kleinbaum D, Kupper L, Muller K, Nizam A. Poisson regression analysis. Applied regression analysis and other multivariable methods. 1998;3:687-709.
  25. Nazarpoor M, Morgan P. Inflow effect correction in perfusion measurement of normal subjects with T1-weighted images using inversion recovery sequences. Iranian Journal of Radiology. 2010;7(3):145-51.
  26. Nazarpoor M. The effect of inversion times on the minimum signal intensity of the contrast agent concentration using inversion recovery t1-weighted fast imaging sequence. Med J Islam Repub Iran. 2014;28:128.
  27. Nazarpoor M. Evaluation of flow measurement from the first pass bolus T 1 weighted images using inversion recovery sequence. The British journal of radiology. 2011;84:342-9. doi: 10.1259/bjr/18588668.
  28. Nazarpoor M, Poureisa M, Daghighi M. Investigations of optimal dose of contrast agent concentration from routine dose using spin echo and inversion recovery T1-weighted sequences in MRI. Medical Journal of Tabriz University of Medical Sciences & Health services. 2013;34:74-8.