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F.M. Kirby Research Center / Philips Achieva 7T MRI Research System

Clinical Research Center

The Kennedy Krieger Institute Clinical Research Center, 716 N. Broadway houses the Philips 7T Achieva MRI. The building is located directly across Broadway from the Johns Hopkins Broadway Research Building, between the Metro station entrance and Madison Street. This is diagonally across from the KKI 707 N. Broadway Building where the F.M. Kirby Research Center's two 3T MRI's, Hi-Field Animal Imaging Center and offices are located. The 7T scanner is housed in the north end of the basement level (toward Madison Street).

Expand your Existing protocol for 7T Scanning

Currently Operating Ultra High Field Whole Body MRI Sites

Construction Details

Magnetic Shielding

The 7T Magnex magnet used for this scanner is not self-shielding as are most superconducting 1.5T and 3T magnets used today in MR scanners. As a result a 440 ton (400 metric ton), 6 sided, steel shield box was constructed to contain the magnetic field. This box forms the largest part of the MR examination room; there is an area of the exam room at the front of the magnet, that is outside the shield box called the RF Porch. Openings about 8 by 8 feet square in the front and back of the box allow passage into and out of the shielded area. The box walls are thickest (16 inches) at the center of the four walls that parallel the magnet's long axis (the 2 long sides and top and bottom), stepping down to 8 inches at the two ends. The steel used for the shield is an alloy that has high magnetic permeability and was annealed after the plates were formed and cut to size to further increase permeability. Since the magnet must be perfectly centered in the box, the box is sunken below floor level into the "MR pit". The bottom of the box is filled with concrete and high density foam blocks to form the floor the magnet sits on.

Vibration Isolation

Due the the proximity of the Metro and heavy traffic on Madison Street and Broadway, the scanner needs to be isolated from vibrations. The entire MR examination room, including the 440 ton shield with it's infill, the 35 ton magnet and all exam room interior finishes are suspended on a Hammond Kinetics air spring isolation system. Twenty-six pressurized air springs lift the room approximately 1/4 inch providing complete isolation from outside vibrations. Three level sensors regulate the air pressure in the air springs keeping the room level.

Cross Section

The air springs were set into place on March 4, 2008 before the concrete base that sits on the springs was formed and poured. This allowed use of a fork lift to move the 300 pound air spring units into place rather than having to move them by hand and hoist down the pit access shaft. This concrete base is shaped like a giant bathtub, with a bottom and four sides that come up the sides of the pit the reach the finished floor level of the basement. The bottom approximately 4 feet of the steel shield box will sit in this bathtub.

Space under the "bathtub" in the bottom of the MR pit, allows access to service the air springs. This is reached via a vertical shaft with ladder and hoist in case one of the air springs ever needs to be replaced. The springs are arranged in 4 rows down the long dimension of the scan room, one row along the left and right walls and a double row down the center. Access aisles run along each row.

MR Pit
MR scanner pit is complete; behind the basement walls are being formed and poured.
MR Pit
The supports for the air springs are being formed on the left, the center support is complete, the right is in place but still needs the raised blocks that support the bathtub when the air springs are deactivated.
air spring install
Hammond Kinetics air spring installation, March 4. The air springs are stacked 2 or 3 high on the center support pier since the left and right piers are not completed. The support blocks are visible between each stack of air springs. These will support the concrete bathtub when the air spings are not inflated.
air spring install
The forms for the bathtub are being constructed. The support blocks are left exposed and covered only with plastic so the bathtub will be siting directly on these blocks after the concrete is poured. The forms covering the aisles and air springs will be removed from below.
forms
Completed forms for the outside of the concrete "bathtub" on March 14, 2008.
shield
Start of assembly of the magnetic shield (April 23)
shield
440 tons of staged shield plates in the basement. Each plate is designed to weigh 10,000 lbs or less.
shield
Stack of four 2 inch plates forming bottom of shield box - more layers will be added to center of box
shield
Peter van Zijl (left) and Joe Gillen (right) of Kirby Center with Richard Lee of Shreveport, LA, the steel erector who is building the MR shield under contract with Imedco and Philips
shield
Overhead view on April 24. You can see the opening in the basement wall through which the magnet will be rigged in late November.
shield
Foam blocks are installed in the bottom infill space of the shield on May 2. This decreases weight on the air spring system compared to a solid concrete infill.
shield
Poured concrete floor inside the shield is completed May 8. Wall assembly continuing.
shield
Overhead on May 16.
shield
Sides complete - beginning assembly of the top May 19.
shield
Shield box complete, structural steel erection started, June 5.
shield
7T Magnet being loaded at Magnex facility in Oxford,
shield
England for shipment by boat to New York on November 1.
shield
Crated and covered for transport.
shield
RF porch copper shielding - projector waveguide and door to left, power line filters visible on ceiling
shield
Framing started inside scan room
shield
Magnet arriving at KKI on Saturday November 22 10:46am.
shield
11:30am - 200 ton crane lifting magnet onto transport dollies
shield
12:00 noon - Magnet being moved inside onto cribbing. The 100 ton jacks are visible that will lower the magnet down to the floor.
shield
4:43pm - Almost down to the floor.
shield
Sunday Nov 23 9:22am - Magnet moving toward scan room.
shield
10am - Making the turn into the scan room.
shield
11am - Only 2 inch clearance each side into the scan room.
shield
500 liter liquid helium dewar being delivered.
shield
Helium dewars staged for the magnet fill.
Control Room
Control Room
magnet room
Scan Room
RF Porch
Scan Room, RF Porch right - projector waveguide, shielded cameras and lab penetration panel visible
RF Porch
Scan Room, RF Porch left - projector waveguide, shielded cameras and coil storage visible
Equipment room
Equipment Room
Prep Room
Prep Room
Back Area
Back of Scan Room - back wall of 400 tonne shield (red), projector (on table), 300kVA UPS visible
Back Area
Back of Scan Room
fMRI Console
fMRI Console (MRA, Inc.) for controlling video and audio stimulus and acquiring responses via fiber-optic buttons
floorplan
7T MRI Suite Floor Plan
Shield Test
Final RF Shield Test Results

Construction Time

Fence in Parking Lot, Demolition & Grading 09/18/07 10/05/08
Drill Sheeting & Shoring Piles and Caissons 10/09/07 12/03/07
Mass Excavation of Building Basement 12/04/07 01/10/08
Construct MRI Pit 01/16/08 02/29/08
Install Airbags 03/03/08 03/05/08
MRI Room Slab 03/06/08 04/03/08
Pour Basement Slab & Walls 03/28/08 04/08/08
Install 440 ton Magnetic Shield 04/16/08 06/02/08
Erect Structural Steel 06/03/08 08/12/08
Pour Elevated Slabs and Rooftop Slab 08/13/08 09/12/08
Exterior - Masonry, Roofing & Windows 09/04/08 12/01/08
7T Magnet ships from UK 10/01/08
Install MRI RF Shield 10/02/08 10/26/08
RF Shield Test 10/27/08
Rig and Set 70,000 lb. 7T Magnet 11/22/08 11/23/08
MRI Suite Framing, MEP & Finishes 11/28/08 01/31/09
Magnet Installation by Magnex/Varian 01/29/09 02/27/09
Cryostat vacuum 01/29/09 02/02/09
Cryostat pre-chill with liquid nitrogen 02/02/09 02/08/09
Cryostat fill with liquid helium 02/10/09 02/16/09
Magnet ramping to 7T 02/19/09 02/22/09
Magnet shimming 02/23/09 02/24/09
Cryocoolers off due to chilled water system failure 02/26/09 03/06/09
Magnet radiation shield cool down 03/06/09 03/20/09
Magnet persistance and boil-off checks 03/19/09 03/20/09
Magnet acceptance 03/20/09
MR Equipment Installation by Philips 01/26/09 03/27/09
Cabinets placed and cabled, magnet room cabled 02/02/09 02/18/09
Magnet covers, patient couch placement 03/05/09 03/11/09
Power test & pre cals ECC 03/23/09 03/24/09
Gradient ECC 03/24/09
RF coil tests 03/22/09 03/25/09
Final system calibrations 03/25/09 03/27/09
PTS data collection 03/25/09
Operational 7T Scanner 04/02/09
7T Training 04/06/09 04/07/09

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