Asim Zia Mian MD, Presenter: Stockholder, Boston Imaging Core Lab, LLC

Hernan Jara PhD, Abstract Co-Author: Patent holder, qMRI algorithms Research Grant, General Electric Company Royalties, World Scientific Publishing Co

Osamu Sakai MD, PhD, Abstract Co-Author: Speaker, Bracco Group Speaker, KYORIN Holdings, Inc Speaker, Eisai Co, Ltd

Stephan W. Anderson MD, Abstract Co-Author: Nothing to Disclose

Jorge A. Soto MD, Abstract Co-Author: Nothing to Disclose

Alexander M. Norbash MD, Abstract Co-Author: Stockholder, Boston Imaging Core Laboratories, LLC Co-founder, Boston Imaging Core Laboratories, LLC

Gadolinium-based contrast agents can have risks including nephrogenic systemic fibrosis, allergic reactions and limitation of use during pregnancy. Normal saline (NS) is a nontoxic sodium chloride water solution that can significantly increase the MR relaxation times of blood via hematocrit reduction. The purpose of this study was to test in-vivo the potential of NS as a safer, brain perfusion exogenous contrast agent.

This HIPAA compliant prospective study was approved by the IRB of our hospital. MRI was performed at 1.5T (Achieva, Philips Healthcare): head array and body coil for RX/TX. Three and five patients were scanned with an IR-EPI and IR-TSE sequence, respectively. The IR pulse sequence was run during and after the NS injection for up to 5min: 100cc of NS were power injected into antecubital veins at 3-4cc/s. Images were processed with Mathcad (2001i, PTC, Needham, MA) algorithms to map maximum enhancement (maxENH), area under the curve (AUC), time-to-peak (TTP), and mean-transit-time (MTT) (Fig. 1a). These maps were used to identify visually the areas showing significant NS injection related signal. Regions of interest (ROI) were drawn in areas of high injection related effects as well as areas without these effects and graphed as a function of time.

NS injection-related enhancement effects were observed in all patients, particularly in highly vascular intra- and extra-cranial tissues and also in periventricular white matter. Relative signal change in cortical gray matter and periventricular white matter were observed in the 10-30% range and these enhancement effects lasted for several minutes post injection (Fig. 1b). All recruited patients completed the NS injection plus the dynamic-IR-MRI scan without any adverse effects, or expressing discomfort.

A measurable perfusion effect of up to 30% change relative to baseline has been demonstrated in-vivo in the human brain using NS as a contrast agent. The contrast mechanism is believed to be an alteration of the T1 relaxation time resulting from hematocrit reduction. To the best of our knowledge, this is the first report of the use of NS for dynamic contrast enhanced MRI.

This demonstrates the viability of NS as a measurable, safe, practical, and inexpensive T1 contrast agent for dynamic perfusion MRI. The described methodology could be used with patients with Gd contraindications.

Mian, A, Jara, H, Sakai, O, Anderson, S, Soto, J, Norbash, A, Proof of Concept: Potential of Normal Saline (NS) as a Safe Exogenous Contrast Agent for Perfusion MRI of the Brain.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14014077.html