Erick Amarteifio MD, Presenter: Nothing to Disclose

Armin Nagel Dipl Phys, Abstract Co-Author: Nothing to Disclose

Frank Lehmann-Horn PhD, Abstract Co-Author: Nothing to Disclose

Karin Jurkat-Rott PhD, Abstract Co-Author: Nothing to Disclose

Hans-Ulrich Kauczor MD, Abstract Co-Author: Research grant, Siemens AG Research grant, Toshiba Corporation Research Consultant, Boehringer Ingelheim GmbH Speakers Bureau, Boehringer Ingelheim GmbH Research grant, Boehringer Ingelheim GmbH Speakers Bureau, Novartis AG

Marc-Andre Weber MD, Abstract Co-Author: Nothing to Disclose

To implement a non-invasive 23sodium MRI technique at 3-Tesla for detecting changes of intracellular sodium concentration in patients with muscular sodium channel diseases.

5 patients with hypokalemic periodic paralysis (HypoPP), 4 patients with hyperkalemic periodic paralysis (HyperPP) and 1 patient with paramyotonia congenita (PC), as well as 3 healthy volunteers were examined on a 3-Tesla clinical MR system (Magnetom Trio, Siemens Medical Solutions, Erlangen, Germany) before and after provocation by cooling. Three sodium pulse sequences based on a density adjusted 3D radial sequence were used. First the sodium concentration was measured (spin density image contrast, TE/TR=0.2ms/100ms; α=90°; voxel size: 5x5x5mm3; 8min20s). Then a T1 image contrast was used to get a higher weighting of the intracellular sodium signal (TE/TR=0.25ms/6ms; α=40°; voxel size: 5x5x5mm3, 5min36s). At last an inversion recovery (IR) sequence was used to suppress the sodium signal from vasogenic edema (TE/TR=0.3ms/124ms; TI=34ms; voxel size: 6x6x6mm3, 10min 20s). With the selected inversion time a complete signal suppression of a reference tube filled with 0.3% saline solution was obtained. The signal of another reference tube containing 0.3% sodium bounded with agarose gel was not eliminated. The latter reference tube was used for standardization. 

Cooling induced a reversible muscle paralysis and an increase in sodium signal within the soleus muscle of above 10% using the IR sequence and a slight signal increase using the T1 image contrast. No detectable increase was found in the spin density image contrast. The non-provoked leg of each patient and the legs of the volunteers showed no relevant increase in sodium signal (< 5%).

The extracellular sodium concentration is ten times higher than the intracellular concentration, which falsifies the measurement of intracellular sodium using standard sodium MRI approaches. The established IR sequence allows by utmost suppression of the extracellular sodium signal a dedicated analysis of intracellular sodium homeostasis.

With the implemented sodium inversion recovery sequence changes of the intracellular sodium concentration in vivo can now be detected with MRI. 

Amarteifio, E, Nagel, A, Lehmann-Horn, F, Jurkat-Rott, K, Kauczor, H, Weber, M, Optimized in Vivo Analysis of Intracellular Sodium Concentration at 3 Tesla.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8011833.html