Yaqi Shen PhD, MD, Abstract Co-Author: Nothing to Disclose

Christopher George Snyder BS, Abstract Co-Author: Nothing to Disclose

Frank Lee Goerner PhD, Presenter: Research Grant, Siemens AG Research Grant, Bayer AG Research Grant, Bracco Group

Regina Moritz, Abstract Co-Author: Nothing to Disclose

Val Murray Runge MD, Abstract Co-Author: Research Grant, Bayer AG Research Grant, Bracco Group

The current available values for T1 relaxivity (r1) of Gadolinium based MR contrast agents (GBCAs) at 1.5T and 3T are either provided for non-clinically relevant scenarios or in only a portion of the available GBCAs. This is likely due to the complex nature of obtaining these values. This study determines and compares the r1 values of eight commercially available GBCAs in human whole blood at 1.5T and 3T.

Eight GBCAs, specifically Dotarem, Gadovist , Magnevist, MultiHance, Omniscan, Optimark, Primovist , and ProHance were serially diluted in pooled human whole blood, at 7 concentrations from 0.0625 to 4 mmol/L. A custom-built phantom held the dilutions in air tight cylindrical tubes immersed in water that was used to adjust temperature. The samples were evaluated using a 15 channel transmit/receive knee coil at 3T and at 1.5T using an 8-channel knee coil. All MR measurements were performed with the GBCA samples at 37±0.5℃ employing a heated water circulating system and MR compatible temperature probe to maintain constant temperature. Inversion recovery sequences with TIs from 30ms to 10s were used to image the samples. A custom Matlab program was used to automate signal intensity measurements in the phantom. SigmaPlot was used to calculate T1 relaxation times and r1. Measured r1 values were compared to those in previous publications with paired t-tests.

Measured r1 values in units of L∙mmol-1s-1 at 1.5T(3T) were 3.9±0.2(3.4±0.4) for Dotarem, 4.6±0.2(4.5±0.3) Gadovist, 4.3±0.4(3.8±0.2) Magnevist, 6.2±0.5(5.4±0.4) MultiHance, 4.5±0.1(3.9±0.2) Omniscan, 4.4±0.2(4.2±0.2) Optimark, 7.2±0.2(5.5±0.3) Primovist, and 4.4±0.6(3.5±0.6) ProHance. The results from this experiment were significantly different from previous experiments (see figure).

As expected at 3T, the r1 values of all GBCAs were lower than those at 1.5T. The r1 values also differed from previously published values. These results are the most relevant r1 measurements to a clinical scenario. This is the only report that has measured r1 of eight GBCAs in whole human blood at normal human body temperature 37±0.5℃.

The results of this experiment are the most relevant r1 measurements to a clinical scenario. This will give clinicians a more accurate idea of the enhancement of each GBCA in MR imaging.

Shen, Y, Snyder, C, Goerner, F, Moritz, R, Runge, V, Accurate T1 Relaxivities (r1) of Gadolinium-based Magnetic Resonance Contrast Agents (GBCAs) in Human Whole Blood at 1.5T and 3T.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13020104.html