Purchase Description 75N95022Q00340.pdf

Version 11-30-2016-1 FAR Part 11—Describing Agency Needs

PURCHASE DESCRIPTION

1. Statement of Need and Purpose: The National Institute on Aging (NIA) requires a sodium-proton (23Na/1H) head coil for sodium brain imaging on the 3T Philips MRI scanner, located at Harbor Hospital in Baltimore. This new coil will allow NIA to detect neuronal death, white matter degradation and edema associated with neurodegenerative diseases such as Alzheimer's disease (AD) and vascular dementia. This capability will augment the research program on the etiology of these diseases in humans.

2. Background Information and Objective:

Sodium, 23Na, is a naturally abundant nucleus that has been used for Magnetic Resonance (MR) imaging, including in-vivo clinical studies of brain aging and neurodegeneration. For example, 23Na MR imaging has been shown to be very sensitive to cell death, one of the hallmarks of AD.

In the human brain, 23Na is distributed in two compartments: intracellular and extracellular, with a constant concentration gradient maintained between these two compartments via the sodium/potassium pump. Impairment of energy metabolism or cell integrity leads to a disruption of this ionic homeostasis and non-normative intra- and extracellular 23Na concentrations. It has been shown that accumulation of 23Na in white matter lesions may be related to increases in 23Na concentration inside either the extra- or intra-cellular (or both) compartments. The former could be related to edema, while the latter may be a consequence of demyelination or gliosis.

This high sensitivity and specificity makes 23Na MRI a powerful noninvasive modality to characterize AD pathophysiology. The ongoing availability of modern coil designs, pulse sequences, and image reconstruction methods have led to a significant increase in the application of 23Na MRI in clinical research in recent years. Moreover, the emergence of promising techniques, such as inversion recovery and triple quantum-filtered sodium imaging, enables the selective characterization of different sodium compartments. These outcome measures have the potential to serve as sensitive biomarkers of early impairment in dementia.

Thus, incorporating 23Na MRI into NIA’s integrative program f MR-based dementia studies, with clinical and functional correlates, would represent a fundamental expansion of our capabilities and place us at the forefront of this important class of MR studies. In conjunction with NIA’s large multifaceted database of metabolic and functional parameters, researchers anticipate that these studies will provide insight into electrophysiological activity, membrane transport, and other cellular processes in the brain that are notably understudied in normal aging and dementia.

3. Generic Name of Product: Sodium-23/Proton (23Na/1H) head array coil for 3T MRI scanner

4. Purchase Description: 23Na 1H phased array for human head; RAPID MR International, LLC.; part number P-XQS-X08LE-HQ-030

5. Salient characteristics:

a. Must be capable of transmitting and receiving at the sodium-23 (23Na) frequency of a 3T MRI scanner (33.8 MHz) to acquire a sodium-23 spectrum of a selected brain region.

b. Must be capable of transmitting and receiving at the proton frequency of a 3T MRI scanner (127.7 MHz) to generate proton images for sodium voxel placement and registration.

c. Must fit within the body coil of a Philips 3T MR7700 MRI scanner and fasten securely to the bed of scanner to avoid image artifacts.

Version 11-30-2016-1 FAR Part 11—Describing Agency Needs

d. Must have an inner diameter of at least 26 cm to comfortably fit subject’s head.

e. Must have an active coil length of at least 24 cm to scan the entire brain in the superior-inferior direction.

f. Must have a radio-frequency and DC electrical interface compatible with a Philips 3T MR7700 scanner.

g. Must include probe description files and any other code needed to interface the coil to the scanner’s acquisition software (Gyroscan R5.9 / R11.1 or above).

h. Must incorporate quadrature polarization on proton channel to maximize efficiency for 1H spin excitation and signal reception.

i. Must be capable of exciting and receiving a proton NMR spectrum of a standard sodium phantom with a minimum signal-to-noise ratio of 20:1 in one scan and a maximum line width (full width at half maximum) of 10 Hz in order to produce proton images of sufficient quality to allow reliable sodium voxel placement.

j. Must incorporate quadrature polarization and active decoupling on sodium-23 transmit channel to maximize efficiency for 23Na spin excitation.

k. Must demonstrate ability to excite sodium-23 (23Na) nuclei in a standard sodium phantom with flip angles from 10 degrees to 270 degrees with an error of no more than 5% from the theoretical sinusoidal dependence of integrated signal on flip angle. This is needed to prevent artifacts in spin-echo and stimulated-echo experiments in which 23Na must be excited with precise flip angles.

l. Must incorporate eight sodium-23 receive channels and active decoupling to maximize sensitivity for 23Na signal reception.

m. Must receive a sodium-23 signal from a standard sodium phantom with a minimum signal-to-noise ratio of 20:1 in one scan and a maximum line width (full width at half maximum) of 10 Hz in order to achieve adequate sensitivity in human brain spectroscopy experiments.

6. Quantity: 1

7. Delivery Date: Approximately 9 months ARO