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Laboratory engineer

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Mikko's group

Group leader

Post Doc researchers

Ph.D. students


Osteoarthritis increasingly causes personal burden and costs to the society with the increasing life expectancy. Magnetic resonance imaging (MRI) and especially quantitative MRI methods are the most sensitive for diagnostics of osteoarthritis. The group investigates a number of different MRI contrasts and imaging methods for the use in diagnostics of articular cartilage and bone disorders, such as OA. Focuses of the research have been in assessing the utility of novel methods, such as quantitative susceptibility mapping (QSM) and different rotating frame of reference relaxation methods, such as adiabatic T1rho and relaxation along a fictituous field (RAFF) for the diagnosis of OA. Most of the research is conducted on ex vivo tissue (bone and cartilage) explants at high magnetic field, 9.4 tesla. To establish the utility and potential of a specific method, a wide variety of reference techniques are applied, to understand in depth what the properties of the tissue explant are and how the new MRI methodology relates to them.

Besides investigating new methods, another focus of the research is in investigating various issues related to different methods, such as the orientation dependence (orientation anisotropy) of the different quantitative MRI methods and the relaxation parameters, with a nice overview given in Hänninen et al, Sci Rep 2017, describing the orientation dependence of a number of quantitative MRI methods in cartilage.

Since articular cartilage, especially the deep layers of cartilage let alone the underlying bone, have extremely rapid T2* relaxation times, the signal of these tissues is quickly lost with traditional MRI methods. Such properties of the tissue call for the use of ultra-short echo time imaging. Methods in the family of "echoless" or zero echo time or ultra-short echo time include for example ZTE (Zero echo time imaging), UTE (Ultra-short echo time imaging) and SWIFT (SWeep Imaging with Fourier Transform). These methods allow depicting all of the tissues in joints.


Follow the links below for the methods.

Recent publications

  • Nykanen O, Sarin JK, Ketola JH, Leskinen H, Te Moller NCR, Tiitu V, Mancini IAD, Visser J, Brommer H, van Weeren PR, Malda J, Toyras J and Nissi MJ. T2* and quantitative susceptibility mapping in an equine model of post-traumatic osteoarthritis: assessment of mechanical and structural properties of articular cartilage. Osteoarthritis Cartilage. 2019 Oct;27(10):1481-1490. doi: 10.1016/j.joca.2019.06.009. Epub 2019 Jul 2.

  • Toth F, ORCID:, Johnson CP, ORCID:, Mills B, Nissi MJ, ORCID:, Nykanen O, ORCID:, Ellermann J, ORCID:, Ludwig KD, ORCID:, Tompkins M, ORCID:, Carlson CS and ORCID: Evaluation of the Suitability of Miniature Pigs as an Animal Model of Juvenile Osteochondritis Dissecans. J Orthop Res. 2019 Oct;37(10):2130-2137. doi: 10.1002/jor.24353. Epub 2019 Jun 18.

  • Nykanen O, ORCID: 0000-0001-7329-3463, Rieppo L, Toyras J, Kolehmainen V, Saarakkala S, Shmueli K, ORCID: 0000-0001-7520-2975, Nissi MJ and ORCID: 0000-0002-5678-0689. Quantitative susceptibility mapping of articular cartilage: Ex vivo findings at multiple orientations and following different degradation treatments. Magn Reson Med. 2018 Dec;80(6):2702-2716. doi: 10.1002/mrm.27216. Epub 2018 Apr 24.

  • Kajabi AW, Casula V, Nissi MJ, Peuna A, Podlipska J, Lammentausta E, Saarakkala S, Guermazi A and Nieminen MT. Assessment of meniscus with adiabatic T1rho and T2rho relaxation time in asymptomatic subjects and patients with mild osteoarthritis: a feasibility study. Osteoarthritis Cartilage. 2018 Apr;26(4):580-587. doi: 10.1016/j.joca.2017.12.006. Epub 2017 Dec 18.

  • Hanninen N, ORCID: 0000-0003-0392-8552, Rautiainen J, Rieppo L, Saarakkala S and Nissi MJ. Orientation anisotropy of quantitative MRI relaxation parameters in ordered tissue. Sci Rep. 2017 Aug 29;7(1):9606. doi: 10.1038/s41598-017-10053-2.

  • Rautiainen J, Nieminen MT, Salo EN, Kokkonen HT, Mangia S, Michaeli S, Grohn O, Jurvelin JS, Toyras J and Nissi MJ. Effect of collagen cross-linking on quantitative MRI parameters of articular cartilage. Osteoarthritis Cartilage. 2016 Sep;24(9):1656-64. doi: 10.1016/j.joca.2016.04.017. Epub 2016 Apr 30.

  • Nissi MJ, Salo EN, Tiitu V, Liimatainen T, Michaeli S, Mangia S, Ellermann J and Nieminen MT. Multi-parametric MRI characterization of enzymatically degraded articular cartilage. J Orthop Res. 2016 Jul;34(7):1111-20. doi: 10.1002/jor.23127. Epub 2015 Dec 31.

  • Nissi MJ, Toth F, Wang L, Carlson CS and Ellermann JM. Improved Visualization of Cartilage Canals Using Quantitative Susceptibility Mapping. PLoS One. 2015 Jul 13;10(7):e0132167. doi: 10.1371/journal.pone.0132167. eCollection 2015.

  • Nissi MJ, Mortazavi S, Hughes J, Morgan P and Ellermann J. T2* relaxation time of acetabular and femoral cartilage with and without intraarticular gadopentetate dimeglumine in patients with femoroacetabular impingement. AJR Am J Roentgenol. 2015 Jun;204(6):W695-700. doi: 10.2214/AJR.14.13428.

  • Rautiainen J, Nissi MJ, Liimatainen T, Herzog W, Korhonen RK and Nieminen MT. Adiabatic rotating frame relaxation of MRI reveals early cartilage degeneration in a rabbit model of anterior cruciate ligament transection. Osteoarthritis Cartilage. 2014 Oct;22(10):1444-52. doi: 10.1016/j.joca.2014.04.023.

  • Nissi MJ, Lehto LJ, Corum CA, Idiyatullin D, Ellermann JM, Grohn OHJ and Nieminen MT. Measurement of T1 relaxation time of osteochondral specimens using VFA-SWIFT. Magn Reson Med. 2015 Jul;74(1):175-184. doi: 10.1002/mrm.25398. Epub 2014 Aug 8.

  • Rautiainen J, Nissi MJ, Salo EN, Tiitu V, Finnila MAJ, Aho OM, Saarakkala S, Lehenkari P, Ellermann J and Nieminen MT. Multiparametric MRI assessment of human articular cartilage degeneration: Correlation with quantitative histology and mechanical properties. Magn Reson Med. 2015 Jul;74(1):249-259. doi: 10.1002/mrm.25401. Epub 2014 Aug 7.

  • Nissi MJ, Toth F, Zhang J, Schmitter S, Benson M, Carlson CS and Ellermann JM. Susceptibility weighted imaging of cartilage canals in porcine epiphyseal growth cartilage ex vivo and in vivo. Magn Reson Med. 2014 Jun;71(6):2197-205. doi: 10.1002/mrm.24863. Epub 2013 Jul 15.

  • Rautiainen J, Lehto LJ, Tiitu V, Kiekara O, Pulkkinen H, Brunott A, van Weeren R, Brommer H, Brama PA, Ellermann J, Kiviranta I, Nieminen MT and Nissi MJ. Osteochondral repair: evaluation with sweep imaging with fourier transform in an equine model. Radiology. 2013 Oct;269(1):113-21. doi: 10.1148/radiol.13121433. Epub 2013 May 14.

  • Nissi MJ, Rieppo J, Toyras J, Laasanen MS, Kiviranta I, Nieminen MT and Jurvelin JS. Estimation of mechanical properties of articular cartilage with MRI - dGEMRIC, T2 and T1 imaging in different species with variable stages of maturation. Osteoarthritis Cartilage. 2007 Oct;15(10):1141-8. doi: 10.1016/j.joca.2007.03.018. Epub 2007 May 21.

  • Nissi MJ, Rieppo J, Toyras J, Laasanen MS, Kiviranta I, Jurvelin JS and Nieminen MT. T(2) relaxation time mapping reveals age- and species-related diversity of collagen network architecture in articular cartilage. Osteoarthritis Cartilage. 2006 Dec;14(12):1265-71. doi: 10.1016/j.joca.2006.06.002. Epub 2006 Jul 14.

  • Nissi MJ, Toyras J, Laasanen MS, Rieppo J, Saarakkala S, Lappalainen R, Jurvelin JS and Nieminen MT. Proteoglycan and collagen sensitive MRI evaluation of normal and degenerated articular cartilage. J Orthop Res. 2004 May;22(3):557-64. doi: 10.1016/j.orthres.2003.09.008.

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