Andriy Babsky PhD, Presenter: Nothing to Disclose

Sheng Hong Ju MD, PhD, Abstract Co-Author: Nothing to Disclose

Stephen Topper, Abstract Co-Author: Nothing to Disclose

Stacy L. Bennett, Abstract Co-Author: Nothing to Disclose

Bharath Atthe, Abstract Co-Author: Nothing to Disclose

Gordon McLennan MD, Abstract Co-Author: Grant, Genentech, Inc

Navin Bansal PhD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

The hepatocellular carcinoma (HCC) growth is associated with structural and metabolic transformation in liver that can be monitored by non-invasive 23Na and 1H MRI. Both the water apparent diffusion coefficient (ADC) and the total tissue Na+ changes reflect mostly the compartmental alterations in tumor tissue, while the intracellular Na+ reflects physiological and metabolic transformation in HCC cells. The water ADC measurement in the rat intrahepatic (IH) HCC model is challenging due to effect of the respiratory and cardiac motion. The effects of untreated growth on water ADC, total tissue Na+ (from SQ 23Na MRI), and intracellular Na+ (from TQF 23Na MRI) were compared in IH and subcutaneous (SC) HCC.

SQ and TQF 23Na MRI, and 1H diffusion weighted imaging (DWI) were performed on SD rats with IH and SC HCC tumors. MR images were acquired with a Varian 9.4 Tesla, 31-cm horizontal bore system. Each animal was examined every week for 4 weeks after injection of 1 - 10 × 106 N1S1 cells into the left liver lobe or under the thigh skin. Water ADCs in HCCs and nearby tissues were measured with coils tuned to 400 MHz using DWI sequence. 3D 23Na MR images were obtained with loop-gap volume resonators tuned to 106 MHz using a gradient-echo imaging sequence.

After the cell inoculation IH and SC HCCs grew with a doubling time of 3.9 and 11.2 days, respectively. The HCCs growth in both locations was associated with an increase in both total tissue and intracellular 23Na signal intensity (SI). In IH and SC HCCs 1) SQ 23Na SI increased by 7.2% and 4% per day, and 2) TQF 23Na MR SI increased by 8.3% and 6% per day, respectively. During the four weeks in IH HCC the ratio of water ADC to nearby liver was always 1.4 – 1.5, while in SC HCC the ratio of water ADC to nearby muscle was usually 0.5 – 0.6. Furthermore, the IH HCC water ADC showed the trend to decrease by 0.18 ×10-4 mm2/sec per day, while the SC HCC water ADC increased by 0.11×10-4 mm2/sec per day.

Water ADC of the HCC depends on tumor location and motion effect. SQ and TQF 23Na MRI are not affected by motion and show increase in total and intracellular Na+ with untreated growth of both IH and SC tumors.

SQ and TQF 23Na MRI may prove more reliable for monitoring tumor growth and response to therapy of HCC in the clinic because, unlike water ADC measurements, 23Na MRI is insensitive to motion.

Babsky, A, Ju, S, Topper, S, Bennett, S, Atthe, B, McLennan, G, Bansal, N, et al, , Monitoring of the Intrahepatic and Subcutaneous Hepatocellular Carcinoma Growth by 23Na and 1H MRI.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6018572.html