Zentrum f. Medizinische Physik u. Biomedizinische Technik & MR-Hochfeld-Zentrum

MR-Microscopy of small specimenon a Human 7T-Scanner

Andreas Berg

A.Berg, MR-Center 30.11. 2010

Quality control spatial resolution

1.) Paraplegia model in rat spine 2.) osteoarthritis: cartilage bone intervert. Disc 3.) teeth and dental composites

Methodology: hardware

MR-microscopy insert on 7T scanner:

Standard whole body scanner:

Phantoms: test structures d < 100 µm

Results Quality control: Spatial Resolution

Phantoms: Test structures d > 1000 µm

A. Berg, Deutsches Patentamt,

München, DE19904635 , 19.08.1999

1,5 cm

First results: Quality Control: spatial ResolutionSilicon grid in Silicon oil

MR-microscopic images of Silicon grid sets in Silicon oil (finest: a/2 = 32 µm)

Left: sagittal view at increased SNR (32 averages )Top: enlarged area trace of profile is indicatedBottom: profile indicating modulation depth Right: sagittal view for a short protocol

Voxel size:50,9 x 25,4 x 200 µm3 !!!

= 2,6 10-4 mm3

= 0,26 10-9 l

< 10-3 Clinical Voxel size(500 x 500 x 2000 µm)

TM = 1,5 min

SNR = 3,15

TM = 87 min

SNR = 16

A. Berg et al. MR-MICROSCOPY ON A HUMAN 7T-SCANNER; ISMRM/ESMRMB 2010, progr nr. 1048,

MR-microscopy vs. histology: Osteoarthritis

MR-microscopy: A. Berg; Samples and referencing: S. Domayer, J. Hofstätter Univ. klinik f. Orthopädie

Osteoarthritis cartilage-bone interface: MR-microscopy vs histological staining

Histologic staining:Safranin-O

MR-microscopy:TE = 8 msVoxel: 96 x 59 x 240 µm3

MR-microscopy vs histology:

• Intact tissue after measurement

• No damage due to cutting

• No staining necessary

(T2, T1, Diffusivity)

• Low effort,Low preparation - and measurement time

1.) Healthy cartilage (lateral condyle of the knee):

Homogeneous, thick cartilage layer

trabecular network structure

A. Berg, A. Potthast,  P. Starewicz, S. Domayer, J. G. Hofstaetter; MR-Microscopy on a human MR-7T Scanner: Methodology and application to medial osteoarthritic samples of the Knee. ECR 2011 Vienna

MR-Microscopy vs. histology

Size: 250 µm - 50 µm

Small degradation areas below the surface

Presumably: areas of fibrillation and loss of proteoglycane

8 mm

osteoarthritic cartilage (medial condyle of the knee):

5

A. Berg, A. Potthast,  P. Starewicz, S. Domayer, J. G. Hofstaetter; MR-Microscopy on a human MR-7T Scanner: Methodology and application to medial osteoarthritic samples of the Knee. ECR 2011 Vienna

Voxel size = 51 x 51 x 240 µm3

< 10-3 clinical MRI voxel size (500 x 500 x 2000 µm3 )TSE:3D-MTX: 256x 256 x 47TE = 8.2 ms, TR = 2.3 sTM = 16 min

MR-microscopy:

Small degradation areas below the surface

Presumably: areas of fibrillation and loss of proteoglycane

osteoarthritic cartilage (medial compartment of the knee):

MR-Microscopy vs Histology

A. Berg, A. Potthast,  P. Starewicz, S. Domayer, J. G. Hofstaetter; MR-Microscopy on a human MR-7T Scanner: Methodology and application to medial osteoarthritic samples of the Knee. ECR 2011 Vienna

4 mm

3D-multislicing

Pulse sequence:Berg_TSE

Voxel: 51 x 51 x 240 µm3

3D-MTX: 256x 256 x 47TM = 16 min

A. Berg, A. Potthast,  P. Starewicz, S. Domayer, J. G. Hofstaetter; MR-Microscopy on a human MR-7T Scanner: Methodology and application to medial osteoarthritic samples of the Knee. ECR 2011 Vienna

13 mm