Sodium T 2 * relaxation times in human heart muscle

Purpose To determine sodium transverse relaxation (T 2 *) characteristics for myocardium, blood and cartilage in humans. Methods T 2 * measurements were performed using a 3D ECG‐gated spoiled gradient echo sequence. A 1.5 Tesla clinical scanner and a 23 Na heart surface coil were used to examine eight healthy volunteers. In biological tissue, the sodium 23 nucleus exhibits a two‐component T 2 relaxation due to the spin 3/2 and its quadrupolar nature. The long T 2 * components of normal myocardium, blood, and cartilage were quantified. For myocardium, the T 2 * was determined separately for the septum, anterior wall, lateral wall, and posterior wall. Results The long T 2 * relaxation time components of 13.3 ± 4.3 msec (septum 13.9 ± 3.2 msec, anterior wall 13.8 ± 5.4 msec, lateral wall 11.4 ± 4.1 msec, posterior wall 14.1 ± 3.7 msec), 19.3 ± 3.3 msec, and 10.2 ± 1.6 msec, were significantly different for myocardium, blood, and cartilage, respectively ( P < 0.00001, Friedman's ANOVA). Conclusion Measurement of 23 Na T 2 * relaxation times is feasible for different regions of the human heart muscle, which might be useful for the evaluation of cardiac pathologies. J. Magn. Reson. Imaging 2002;15:215–218. © 2002 Wiley‐Liss, Inc.