Biomaterials LaboratoryBiomaterials LaboratoryMartinos Center for Biomedical ImagingMartinos Center for Biomedical Imaging

Massachusetts General Hospital and Harvard Medical SchoolMassachusetts General Hospital and Harvard Medical School

Group Leader: Jerry Ackerman

©1989, National Geographic Society

Investigators and MGH Collaborators•Christian T. Farrar, PhD.•Gyunggoo Cho, Ph.D. (Present address:

Seoul National University Hospital)•Van J. Wedeen, M.D.•Denise P. Hinton, Ph.D.•David A. Chesler, Ph.D.•Janelle Chang, Dartmouth College

Children’s Hospital Collaborators

Laboratory for the Studyof Skeletal Disordersand Rehabilitation•Melvin J. Glimcher, M.D.•Yaotang Wu, Ph.D.•Lila Graham, Ph.D.•Jinxi Wang, M.D., Ph.D.

MissionThe Biomaterials Laboratory develops methods to study natural and synthetic biomaterials using magnetic resonance imaging and spectroscopy.

•Bone mineral•Pathological calcification (atherosclerosis)•Synthetic calcium phosphate ceramic implants•Polymeric implants•Composite implants•Intravascular RF coils

Yaotang

David

Denise

Gyunggoo

Jerry

Chris

Porous Porous ββ--Tricalcium Phosphate Implant PorosityTricalcium Phosphate Implant Porosity

Large Pores Small Pores

Purewater

13 mmimplant

Proton MRI of imbibed water measures internalporosity distribution in porous structures

11H Solid State MRI of Bone MatrixH Solid State MRI of Bone Matrix

Single image planes from full three dimensional data set:Total proton content

Same as above, except with water and fat suppression:Solid proton content(mostly collagen)

Photograph of the bovine bone specimen

Corticalbone

Marrow

Corticalbone

Marrow

Axial Views Longitudinal Views

Projection imaging of free induction decays

Wu, Ackerman, Chesler, Graham, Wang, Glimcher. Density of organic matrix of native mineralized bone measured by water and fat suppressed proton projection MRI. Magn Reson Med. 2003; 50: 59–68.

Cylindrical Meanderline Coil

Flat zig zag (meanderline) coil

Sensitive volume

Van Wedeen, 1992Cylindrical meanderline coil

Magnetic Flux Density |B|, dB

Axial viewTransverse view

Channel forblood flow

Remcom FDTD Simulation

Endarterectomy Specimen

0.1 mm in plane resolution1 mm slice thickness

Birdcage transmit/3 mm meanderline

receive

127 mm birdcagetransmit/receive

Meanderlinecoil

5 mm

3 mm diameter6 wiresCopper cladKapton film

Prototype Cylindrical Meanderline Coil

Intravascular RF CoilsIntravascular RF Coils

Farrar CT, Wedeen VJ, Ackerman JL. The cylindrical meanderline radio frequency coil for intravascular magnetic resonance studies of atherosclerotic plaque. Magn Reson Med. In press.

Full

Free Space

Coil Interior:

Saline Immersed

Experiment:3 mm coil in water

Simulation

Empty

Effect of Loading by Immersion of Coil

Furnace PhotographFurnace Schematic

2000 mm

24 mm ID quartz

44 mm ID Pyrex

54 mm ID Pyrex

Quadrature birdcage coilon split quartz former Ceramic fiber insulation

3 mm water jacket

Thermocouple

Specimen

Thermocouple

Noninductive heater

Water outExpansion vent

Expansion vent

Water in

Viton o-ring seals

Gas out Gas in

Gas out toscrubbers

Aluminum end capNot to scale

Not shown: water and gas pressure gauges and pressure relief valves

2000 mm

24 mm ID quartz

44 mm ID Pyrex

54 mm ID Pyrex

Quadrature birdcage coilon split quartz former Ceramic fiber insulation

3 mm water jacket

Thermocouple

Specimen

Thermocouple

Noninductive heater

Water outExpansion vent

Expansion vent

Water in

Viton o-ring seals

Gas out Gas in

Gas out toscrubbers

Aluminum end capNot to scale

Not shown: water and gas pressure gauges and pressure relief valves

2000 mm2000 mm

24 mm ID quartz24 mm ID quartz

44 mm ID Pyrex44 mm ID Pyrex

54 mm ID Pyrex54 mm ID Pyrex

Quadrature birdcage coilon split quartz formerQuadrature birdcage coilon split quartz former Ceramic fiber insulationCeramic fiber insulation

3 mm water jacket3 mm water jacket

ThermocoupleThermocouple

SpecimenSpecimen

ThermocoupleThermocouple

Noninductive heaterNoninductive heater

Water outWater outExpansion ventExpansion vent

Expansion ventExpansion vent

Water inWater in

Viton o-ring sealsViton o-ring seals

Gas outGas out Gas inGas in

Gas out toscrubbersGas out toscrubbers

Aluminum end capAluminum end capNot to scale

Not shown: water and gas pressure gauges and pressure relief valves

After 5 min

After 10 min

After 5 min

Dewaxing of a Green β-Tricalcium PhosphateCeramic Pellet at 200 °C by Proton MRI

1H spin echo images of a green pellet of β-tricalcium phosphate with 50 weight % polyethylene glycol binder at 200 °C. Field of view = 120 mm, TR = 1 s, TE = 16 ms, number of pixels = 128 x 128, slice thickness = 2 mm, PEG particle size = 100 < mesh < 200.

7Li Spin Echo Images of Molten LiCl at 700 oC

Field of view = 100 mm, TR = 1 s, TE = 16 ms, number of pixels = 64x64, slice thickness = 5 mm.

Transverse

Top Side

LiCl in the sample holder

MR Compatible Furnace for InMR Compatible Furnace for In--Situ MRI ofSitu MRI ofHigh Temperature Materials ProcessingHigh Temperature Materials Processing

Cho G, Segal E, Ackerman JL. Nuclear magnetic resonance-compatible furnace for high temperature MR imaging and spectroscopy in situ. J Magn Reson. 2004; 169: 328–334.

Two Dimensional Solid State NMR Spectroscopy of Bone MineralTwo Dimensional Solid State NMR Spectroscopy of Bone Mineral

1H – 31P heteronuclear correlation (HETCOR) cross polarization/magic angle spinning (CP/MAS)spectroscopy for structural and compositional analysis of bone mineral crystals.

30 20 10 0 -10PPM

10

5

0

-5

PPM

31P spectrum

OH– – PO4–3 signal

1H spectrum

Hydroxyapatite (Ca8(OH)2(PO4)6) +Brushite (CaHPO4·2H2O) test mixture

HPO4–2 signal

30 20 10 0 -10PPM

10

5

0

-5

PPM

31P spectrum

OH– – PO4–3 signal

1H spectrum

Surface water signal

Bone mineral specimen

Do hydroxyl ions exist in thebone mineral crystal lattice?

Historical controversy:possibly not

Unequivocal solid stateNMR evidence:

YES!

Cho, Wu, Ackerman. Detection of hydroxyl ions in bone mineral by solid-state NMR spectroscopy. Science. 2003; 300: 1123–1127.