Measurements of MRI R2* Relaxation Rate in Liver and Muscle: Animal Model
This study was aimed to measure effective transverse
relaxation rates (R2*) in the liver and muscle of normal New Zealand
White (NZW) rabbits. R2* relaxation rate has been widely used in
various hepatic diseases for iron overload by quantifying iron contents
in liver. R2* relaxation rate is defined as the reciprocal of T2*
relaxation time and mainly depends on the constituents of tissue.
Different tissues would have different R2* relaxation rates. The signal
intensity decay in Magnetic resonance imaging (MRI) may be
characterized by R2* relaxation rates. In this study, a 1.5T GE Signa
HDxt whole body MR scanner equipped with an 8-channel high
resolution knee coil was used to observe R2* values in NZW rabbit’s
liver and muscle. Eight healthy NZW rabbits weighted 2 ~ 2.5 kg were
recruited. After anesthesia using Zoletil 50 and Rompun 2% mixture,
the abdomen of rabbit was landmarked at the center of knee coil to
perform 3-plane localizer scan using fast spoiled gradient echo
(FSPGR) pulse sequence. Afterwards, multi-planar fast gradient echo
(MFGR) scans were performed with 8 various echo times (TEs) to
acquire images for R2* measurements. Regions of interest (ROIs) at
liver and muscle were measured using Advantage workstation.
Finally, the R2* was obtained by a linear regression of ln(sı) on TE.
The results showed that the longer the echo time, the smaller the signal
intensity. The R2* values of liver and muscle were 44.8 ± 10.9 s-1 and
37.4 ± 9.5 s-1, respectively. It implies that the iron concentration of
liver is higher than that of muscle. In conclusion, the more the iron
contents in tissue, the higher the R2*. The correlations between R2*
and iron content in NZW rabbits might be valuable for further
exploration.
[1] R. P. Lim, K. Tuvia, C. H. Hajdu, M. Losada, R. Gupta, T. Parikh, J. S.
Babb, B. Taouli, “ Quantification of hepatic iron deposition in patients
with liver disease: comparison of chemical shift imaging with single echo
T2*-weighted imaging,” AJR Am J Roentgenol, vol. 194, no. 5,
1288-1295, May 2010.
[2] E. Szurowska, K. Sikorska, E. Izycka-Swieszewska, T. Nowicki, T.
Romanowski, K. P. Bielawski, M. Studniarek, “ The role of MR imaging
in detection of hepatic iron overload in patients with cirrhosis of different
origins,” BMC Gastroenterol, vol. 10, 13, 2010.
[3] P. Storey, A. A. Thompson, C. L. Carqueville, J. C. Wood, R. A. de
Freitas, C. K.. Rigsby, “R2* imaging of transfusional iron burden at 3T
and comparison with 1.5T,” Magn Reson Imaging, vol. 25, no. 3, pp.
540-547, Mar. 2007.
[4] M. Barry, S. Sherlock, “Measurement of liver-iron concentration in
needle-biopsy specimens,” Lancet, vol. 1, no. 7690, pp. 100–103, Jan.
1971.
[5] G. M. Brittenham, D. E. Farrell, J. W. Harris, E. S. Feldman, E. H.
Danish, W. A. Muir, J. H. Tripp, E. M. Bellon, “Magnetic-susceptibility
measurement of human iron stores,” N Engl J Med, vol. 307, pp. 1671–
1675, Dec. 1982.
[6] E. Angelucci, G. Barosi, C. Camaschella, M. D. Cappellini, M. Cazzola,
R. Galanello, M. Marchetti, A. Piga, S. Tura, “Italian Society of
Hematology practice guidelines for the management of iron overload in
thalassemia major and related disorders,” Haematologica, vol. 93, no. 5,
pp. 741-752, May. 2008.
[7] M. Ulla, J.M. Bonny, L. Ouchchane, I. Rieu, B. Claise, F. Durif, “ Is R2*
a new MRI biomarker for the progression of Parkinson's disease? A
longitudinal follow-up,” PLoS One, vol. 8, no. 3,pp. e57904, Mar. 2013.
[8] J. C. Wood, C. Enriquez, N. Ghugre, J. M. Tyzka, S. Carson, M. D.
Nelson, T. D. Coates, “MRI R2 and R2* mapping accurately estimates
hepatic iron concentration in transfusion-dependent thalassemia and
sickle cell disease patients,” Blood, vol. 106, no. 4, pp. 1460–1465, Aug.
2005.
[9] J. Ma, F.W. Wehrli, “Method for image-based measurement of the
reversible and irreversible contribution to the transverse-relaxation rate,”
J Magn Reson B, vol. 111,no. 1, pp. 61-69, Apr. 1996.
[1] R. P. Lim, K. Tuvia, C. H. Hajdu, M. Losada, R. Gupta, T. Parikh, J. S.
Babb, B. Taouli, “ Quantification of hepatic iron deposition in patients
with liver disease: comparison of chemical shift imaging with single echo
T2*-weighted imaging,” AJR Am J Roentgenol, vol. 194, no. 5,
1288-1295, May 2010.
[2] E. Szurowska, K. Sikorska, E. Izycka-Swieszewska, T. Nowicki, T.
Romanowski, K. P. Bielawski, M. Studniarek, “ The role of MR imaging
in detection of hepatic iron overload in patients with cirrhosis of different
origins,” BMC Gastroenterol, vol. 10, 13, 2010.
[3] P. Storey, A. A. Thompson, C. L. Carqueville, J. C. Wood, R. A. de
Freitas, C. K.. Rigsby, “R2* imaging of transfusional iron burden at 3T
and comparison with 1.5T,” Magn Reson Imaging, vol. 25, no. 3, pp.
540-547, Mar. 2007.
[4] M. Barry, S. Sherlock, “Measurement of liver-iron concentration in
needle-biopsy specimens,” Lancet, vol. 1, no. 7690, pp. 100–103, Jan.
1971.
[5] G. M. Brittenham, D. E. Farrell, J. W. Harris, E. S. Feldman, E. H.
Danish, W. A. Muir, J. H. Tripp, E. M. Bellon, “Magnetic-susceptibility
measurement of human iron stores,” N Engl J Med, vol. 307, pp. 1671–
1675, Dec. 1982.
[6] E. Angelucci, G. Barosi, C. Camaschella, M. D. Cappellini, M. Cazzola,
R. Galanello, M. Marchetti, A. Piga, S. Tura, “Italian Society of
Hematology practice guidelines for the management of iron overload in
thalassemia major and related disorders,” Haematologica, vol. 93, no. 5,
pp. 741-752, May. 2008.
[7] M. Ulla, J.M. Bonny, L. Ouchchane, I. Rieu, B. Claise, F. Durif, “ Is R2*
a new MRI biomarker for the progression of Parkinson's disease? A
longitudinal follow-up,” PLoS One, vol. 8, no. 3,pp. e57904, Mar. 2013.
[8] J. C. Wood, C. Enriquez, N. Ghugre, J. M. Tyzka, S. Carson, M. D.
Nelson, T. D. Coates, “MRI R2 and R2* mapping accurately estimates
hepatic iron concentration in transfusion-dependent thalassemia and
sickle cell disease patients,” Blood, vol. 106, no. 4, pp. 1460–1465, Aug.
2005.
[9] J. Ma, F.W. Wehrli, “Method for image-based measurement of the
reversible and irreversible contribution to the transverse-relaxation rate,”
J Magn Reson B, vol. 111,no. 1, pp. 61-69, Apr. 1996.
@article{"International Journal of Biological, Life and Agricultural Sciences:71448", author = "Chiung-Yun Chang and Po-Chou Chen and Jiun-Shiang Tzeng and Ka-Wai Mac and Chia-Chi Hsiao and Jo-Chi Jao", title = "Measurements of MRI R2* Relaxation Rate in Liver and Muscle: Animal Model", abstract = "This study was aimed to measure effective transverse
relaxation rates (R2*) in the liver and muscle of normal New Zealand
White (NZW) rabbits. R2* relaxation rate has been widely used in
various hepatic diseases for iron overload by quantifying iron contents
in liver. R2* relaxation rate is defined as the reciprocal of T2*
relaxation time and mainly depends on the constituents of tissue.
Different tissues would have different R2* relaxation rates. The signal
intensity decay in Magnetic resonance imaging (MRI) may be
characterized by R2* relaxation rates. In this study, a 1.5T GE Signa
HDxt whole body MR scanner equipped with an 8-channel high
resolution knee coil was used to observe R2* values in NZW rabbit’s
liver and muscle. Eight healthy NZW rabbits weighted 2 ~ 2.5 kg were
recruited. After anesthesia using Zoletil 50 and Rompun 2% mixture,
the abdomen of rabbit was landmarked at the center of knee coil to
perform 3-plane localizer scan using fast spoiled gradient echo
(FSPGR) pulse sequence. Afterwards, multi-planar fast gradient echo
(MFGR) scans were performed with 8 various echo times (TEs) to
acquire images for R2* measurements. Regions of interest (ROIs) at
liver and muscle were measured using Advantage workstation.
Finally, the R2* was obtained by a linear regression of ln(sı) on TE.
The results showed that the longer the echo time, the smaller the signal
intensity. The R2* values of liver and muscle were 44.8 ± 10.9 s-1 and
37.4 ± 9.5 s-1, respectively. It implies that the iron concentration of
liver is higher than that of muscle. In conclusion, the more the iron
contents in tissue, the higher the R2*. The correlations between R2*
and iron content in NZW rabbits might be valuable for further
exploration.", keywords = "Liver, MRI, multi-planar fast gradient echo, muscle,
R2* relaxation rate.", volume = "9", number = "11", pages = "1159-4", }