Peter Fries MD, Presenter: Nothing to Disclose

Roland Michael Seidel MD, Abstract Co-Author: Nothing to Disclose

Andreas Müller, Abstract Co-Author: Nothing to Disclose

Philippe Robert, Abstract Co-Author: Research Consultant, Guerbet SA

Alexander Massmann MD, Abstract Co-Author: Nothing to Disclose

Gero Denda, Abstract Co-Author: Nothing to Disclose

Jens Sperling, Abstract Co-Author: Nothing to Disclose

Guenther Karl Schneider MD, PhD, Abstract Co-Author: Nothing to Disclose

Arno Buecker MD, Abstract Co-Author: Consultant, Covidien AG Speaker, Covidien AG Co-founder, Aachen Resonance GmbH Research, Siemens AG

To compare an experimental high relaxivity Gd-based extracellular contrast agents (HRCA) with a standard extracellular contrast agent (Gd-DTPA) regarding signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and lesion enhancement (LE) at 9.4 T in a rat liver model of colon cancer metastases.

Two groups of WAG-Rij rats (n=10 each) received an injection of 500,000 colon cancer cells (CC531) into the left liver lobe. MRI was performed 12 to 14 days after tumor implantation using a 9.4 T animal scanner (Bruker 92/20, Ettlingen, Germany). One group received 0.2 mmol/kg body weight (BW) Gd-DTPA, the other group received 0.1 mmol/kg BW HRCA intravenously. T1w retrospectively self-gated FLASH sequences (IntraGate, TR/TE 45/2.5ms, flip angle= 45°, acquisition time: 1:23 min, FOV= 5.12x5.12 cm2, matrix: 256x256, voxel size: 0.02x0.02x1.0 mm3) were acquired before and at 4 consecutive time points after contrast injection. SNR of tumor (SNRtumor) and normal liver tissue (SNRliver), contrast-to-noise ratio (CNR) and lesion enhancement (LE) were calculated based on ROI measurements. Statistical analyses included an unpaired t-test and a Mann-Whitney test (p<0.05). Histopathologic evaluation confirmed the presence of metastases in all animals.

SNRliver, SNRtumor, CNR and LE were significantly higher using HRCA for all time points after contrast injection as compared with Gd-DTPA at double clinical dose (P=0.0001 - 0.04 for all time points). SNRliver : unenh., 2 min, 4 min, 6 min, 8 min. Gd-DTPA: 6.7 / 10.4 / 9.1 / 8.4 / 8.8, HRCA: 8.4 / 14.9 / 13.2 / 12.9 / 11.8, SNRtumor: Gd-DTPA: 6.7 / 13.5 /11.7 / 11.0 / 11.0, HRCA: 7.9 / 24.6 / 23.6 / 21.5 / 19.3, CNR: Gd-DTPA: -0.1 / 3.1 / 2.6 / 2.6 / 2.1, HRCA: -0.5 / 9.7 / 10.4 / 8.7 / 7.5, LE: Gd-DTPA: 0.0 / 3.6 / 2.4 / 1.7 / 2.2, HRCA: 0.0 / 16.7 / 15.6 / 13.6 / 11.3.

The experimental HRCA applied @ 0.1 mmol/kg BW demonstrates markedly better contrast enhancement properties as compared to Gd-DTPA @ 0.2 mmol/kg BW. Therefore, this new compound is a highly potent agent for dynamic contrast enhanced studies in animal tumor models at 9.4 T.

This experimental extracellular HRCA can be expected to have a higher sensitivity for detection of liver lesions in both, animals as well as humans, due to its high CNR at ultrahigh field strength.

Fries, P, Seidel, R, Müller, A, Robert, P, Massmann, A, Denda, G, Sperling, J, Schneider, G, Buecker, A, Comparison of an Experimental High Relaxivity Extracellular Gd-based Contrast Agent (HRCA) with Gd-DTPA in a Rat Liver Tumor Model at 9.4 Tesla.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043398.html