D-Attachment-PURCHASE DESCRIPTION Microimaging gradient set and RF coil for 7T pre-clinical MRI scanner.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 an upgrade to the Bruker Biospec 70/30 MRI scanner. This upgrade consists of adding a stronger, 60 mm inner diameter (ID) gradient/shim coil set that may be inserted into the existing 120 mm ID BGA12S-HP gradient/shim system for magnetic resonance imaging and spectroscopy of live mice. Given the same electrical current sources, smaller gradient and shim coils yield greater magnetic field strength. In this instance, the smaller BGA6S-HP gradient insert will yield an increase in gradient strength and slew rate from 660 to 1000 mT/m and from 4570 to 9000 T/m/s, respectively, in each direction (X, Y and Z). In addition, shim strength will increase from 2250 to 6800 Hz/cm2 and from 90 to 650 Hz/cm3 for the Z2 and Z3 channels, respectively. To take advantage of the available inner diameter, the new gradient insert will be paired with a 35 mm ID quadrature radio-frequency (RF) transmit/receive coil, into which a mouse bed can be inserted.

2. Background Information and Objective: Installing the BGA6S-HP gradient/shim insert will increase the maximum gradient strength and slew rate for imaging applications, permitting scanning with thinner slices (i.e., higher resolution) and shorter echo time (TE). This has the advantage of replacing 3D with 2D experiments, which reduces scan time, and enabling the study of tissues such as myelin, cortical bone, tendon, ligament, and mineralized cartilage using ultrashort-TE (UTE) sequences, respectively. In addition, stronger diffusion gradients may be applied in experiments such as diffusion tensor imaging (DTI), thereby facilitating advanced white matter fiber tracking and evaluation of myelin content and integrity. Further, stronger diffusion gradients enable state-of-the-art DTI studies of skeletal muscle and other tissues with low diffusivity.

In addition to the advantages of increased gradient strength and slew rate in imaging applications, installation of the proposed gradient/shim insert will facilitate shimming small voxels in the mouse brain. At present, with the 120 mm ID BGA12S-HP gradient/shim set, we frequently are unable to fully optimize B0 magnetic field shimming in the mouse brain due to hardware limits on shim strength and the large inhomogeneities that exist at interfaces between the cortex and the cranium and sinuses. This, in turn, confounds the acquisition of high-quality localized NMR spectra of metabolites such as N-acetylaspartate (NAA), glucose, lactate and creatine. Moreover, fast imaging techniques that require high B0 homogeneity, such as echo-planar imaging (EPI), which is central to resting state functional imaging (fMRI) studies, and steady-state free precession (SSFP) imaging are difficult to perform on these regions of the mouse brain. By providing stronger shim gradients, the BGA6S-HP gradient/shim set promises to improve image and spectrum quality in the mouse brain and to enable studies of difficult-to-shim brain regions, such as the prefrontal cortex. Thus, the proposed upgrade will both improve the performance of existing imaging methods and open new applications otherwise inaccessible with existing hardware.

3. Generic Name of Product: Microimaging gradient set and RF coil for 7T pre-clinical MRI scanner

4. Purchase Description: Gradient/Shim Insert BGA 6S HP, M/N MT0030, plus 35 mm ID quadrature volume RF coil, M/N MT0570

5. Salient characteristics

a. Performance requirements:

(1) Maximum gradient strength must meet or exceed 1000 mT/m on each channel (X, Y and Z) individually with input current of no more than 200 A at a voltage of no more than 300 V.

(2) Maximum gradient slew rate must meet or exceed 9000 T/m/s on each channel individually with input voltage of no more than 300 V.

(3) Gradient coil must be capable of operating continuously with at least 35 A input current on each channel simultaneously.

(4) Maximum shim strength must meet or exceed 6800 Hz/cm2 on channels Z2, XZ and YZ, 1800 Hz/cm2 on channels X2-Y2 and 2XY and 650 Hz/cm3 on channel Z3 given 10 A input current per channel.

b. Must be physically compatible with existing Bruker 7T 30 cm USR magnet and BGA12S- HP gradient set. This requirement includes:

(1) Must fit inside existing 115 mm ID BGA12S-HP gradient/shim set.

(2) Must include mechanical fixation to BGA12S-HP gradient/shim set and/or to

7T/30 cm USR MRI magnet.

(3) Center of gradient/shim set must reach center of magnet at 752 mm from magnet back flange without removing BGA12S-HP gradient/shim set.

(4) Clear bore diameter must be at least 60 mm through entire length of gradient/shim set.

c. Gradient coils must be electrically and physically compatible with Bruker/IECO gradient amplifiers in BioSpec 70/30 USR MRI scanner with AV3HD console. This requirement includes:

(1) Compatibility with cables and connectors carrying gradient current to gradient coil inside the magnet room.

(2) Must include gradient channels X, Y and Z.

(3) Must exhibit inductance and resistance of X, Y and Z channels within specified limits of existing gradient amplifiers.

d. Shim coils must be electrically and physically-compatible with Bruker 6-channel 10 amp shim current supply in BioSpec 70/30 USR MRI scanner with AV3HD console. This requirement includes:

(1) Compatibility with cables and connectors carrying shim current to shim coil inside the magnet room

(2) Must include shim channels Z2, Z3, 2XY, X2-Y2, XZ and YZ.

(3) Resistance of each shim coil must be compatible with shim current supply’s specified limits.

(4) Must operate with input voltage of at least 60 V per channel.

(5) Must operate with input current of at least 10 A per channel.

e. Gradient and shim coils must be electrically and functionally compatible with GRASI 2 gradient/shim controller in BioSpec 70/30 USR MRI scanner with AV3HD console. This requirement includes:

(1) Compatibility with cables and connectors used by GRASI 2 to monitor gradient/shim coil temperature and thermal overload status

(2) Must include temperature sensors and thermal switches used by GRASI 2 for safety interlock function

f. Gradient/shim coil must be functionally compatible with Bruker ParaVision 6.0.1 software. This requirement includes:

(1) Must support automatic software configuration of gradient and shim parameters when gradient/shim coil is plugged into scanner

(2) Gradient/shim coil must support adjustment of pre-emphasis and RC time constants through ParaVision software interface

(3) Must support calibration of shim strengths for MAPSHIM image-based shimming

g. Must include 35 mm ID quadrature volume coil with the following characteristics:

1) Must fit inside gradient/shim coil and include fixation to gradient/shim coil and/or patient bed.

2) Must connect to Bruker Biospec 70/30 USR MRI scanner with AV3HD console using ODU plug with compatible radio-frequency (RF) and direct current (DC) pins.

3) Must have manual tuning and matching controls for each RF channel.

4) Must support automatic configuration of routing and power limits in ParaVision 6.0.1 software.

6. Quantity: 1

7. Delivery Date: 5-6 months ARO

8. Period of Performance: Installation and startup by 2/1/2023

9. Option(s): None