Limits...
High resolution MRI imaging at 9.4 Tesla of the osteochondral unit in a translational model of articular cartilage repair.

Goebel L, Müller A, Bücker A, Madry H - BMC Musculoskelet Disord (2015)

Bottom Line: A 3D SGE sequence with the parameters: TR = 10 ms, TE = 3 ms, FA = 10°, voxel size = 120 × 120 × 120 μm(3) and NEX = 10 resulted in the best fitting for sample size, image quality, scanning time and artifacts.Specific alterations of the osteochondral unit associated with cartilage repair such as persistent drill holes, subchondral bone cysts, sclerosis of the subchondral bone plate and of the subarticular spongiosa and intralesional osteophytes were precisely detected.In particular, 9.4 T is capable of accurately depicting alterations of the subchondral bone that are associated with osteochondral repair.

View Article: PubMed Central - PubMed

Affiliation: Center of Experimental Orthopaedics, Saarland University Medical Center, Kirrberger Straße, Building 37, Homburg/Saar, D-66421, Germany. Lars.Goebel@uks.eu.

ABSTRACT

Background: Non-destructive structural evaluation of the osteochondral unit is challenging. Here, the capability of high-field magnetic resonance imaging (μMRI) at 9.4 Tesla (T) was explored to examine osteochondral repair ex vivo in a preclinical large animal model. A specific aim of this study was to detect recently described alterations of the subchondral bone associated with cartilage repair.

Methods: Osteochondral samples of medial femoral condyles from adult ewes containing full-thickness articular cartilage defects treated with marrow stimulation were obtained after 6 month in vivo and scanned in a 9.4 T μMRI. Ex vivo imaging of small osteochondral samples (typical volume: 1-2 cm(3)) at μMRI was optimised by variation of repetition time (TR), time echo (TE), flip angle (FA), spatial resolution and number of excitations (NEX) from standard MultiSliceMultiEcho (MSME) and three-dimensional (3D) spoiled GradientEcho (SGE) sequences.

Results: A 3D SGE sequence with the parameters: TR = 10 ms, TE = 3 ms, FA = 10°, voxel size = 120 × 120 × 120 μm(3) and NEX = 10 resulted in the best fitting for sample size, image quality, scanning time and artifacts. An isovolumetric voxel shape allowed for multiplanar reconstructions. Within the osteochondral unit articular cartilage, cartilaginous repair tissue and bone marrow could clearly be distinguished from the subchondral bone plate and subarticular spongiosa. Specific alterations of the osteochondral unit associated with cartilage repair such as persistent drill holes, subchondral bone cysts, sclerosis of the subchondral bone plate and of the subarticular spongiosa and intralesional osteophytes were precisely detected.

Conclusions: High resolution, non-destructive ex vivo analysis of the entire osteochondral unit in a preclinical large animal model that is sufficient for further analyses is possible using μMRI at 9.4 T. In particular, 9.4 T is capable of accurately depicting alterations of the subchondral bone that are associated with osteochondral repair.

No MeSH data available.


Related in: MedlinePlus

Example of poor image quality obtained using μMRI at 9.4 T. The images are blurred with interfolding and doubling of the surface. Axial (a); coronal (b) and sagittal plane (c); SGE sequence, isotropic voxel size 120 μm3. Scale bar = 4 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4404065&req=5

Fig3: Example of poor image quality obtained using μMRI at 9.4 T. The images are blurred with interfolding and doubling of the surface. Axial (a); coronal (b) and sagittal plane (c); SGE sequence, isotropic voxel size 120 μm3. Scale bar = 4 mm.

Mentions: Different imaging artifacts were observed during the scanning progress. Performing several consecutive scans resulted in a continuous warming of the MRI system, the coil and the sample (sample warming of approximately 2 to 3°C). This negatively influenced the quality of the acquired data sets, resulting in decreased SNRs (Figure 2). In this context, the MRI scans also were blurred, often showing a false interfolding and doubling of the surface (Figure 3). These phenomena vanished after cooling of the MRI system, necessitating several MRI scans of the same specimen in some cases.Figure 2


High resolution MRI imaging at 9.4 Tesla of the osteochondral unit in a translational model of articular cartilage repair.

Goebel L, Müller A, Bücker A, Madry H - BMC Musculoskelet Disord (2015)

Example of poor image quality obtained using μMRI at 9.4 T. The images are blurred with interfolding and doubling of the surface. Axial (a); coronal (b) and sagittal plane (c); SGE sequence, isotropic voxel size 120 μm3. Scale bar = 4 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4404065&req=5

Fig3: Example of poor image quality obtained using μMRI at 9.4 T. The images are blurred with interfolding and doubling of the surface. Axial (a); coronal (b) and sagittal plane (c); SGE sequence, isotropic voxel size 120 μm3. Scale bar = 4 mm.
Mentions: Different imaging artifacts were observed during the scanning progress. Performing several consecutive scans resulted in a continuous warming of the MRI system, the coil and the sample (sample warming of approximately 2 to 3°C). This negatively influenced the quality of the acquired data sets, resulting in decreased SNRs (Figure 2). In this context, the MRI scans also were blurred, often showing a false interfolding and doubling of the surface (Figure 3). These phenomena vanished after cooling of the MRI system, necessitating several MRI scans of the same specimen in some cases.Figure 2

Bottom Line: A 3D SGE sequence with the parameters: TR = 10 ms, TE = 3 ms, FA = 10°, voxel size = 120 × 120 × 120 μm(3) and NEX = 10 resulted in the best fitting for sample size, image quality, scanning time and artifacts.Specific alterations of the osteochondral unit associated with cartilage repair such as persistent drill holes, subchondral bone cysts, sclerosis of the subchondral bone plate and of the subarticular spongiosa and intralesional osteophytes were precisely detected.In particular, 9.4 T is capable of accurately depicting alterations of the subchondral bone that are associated with osteochondral repair.

View Article: PubMed Central - PubMed

Affiliation: Center of Experimental Orthopaedics, Saarland University Medical Center, Kirrberger Straße, Building 37, Homburg/Saar, D-66421, Germany. Lars.Goebel@uks.eu.

ABSTRACT

Background: Non-destructive structural evaluation of the osteochondral unit is challenging. Here, the capability of high-field magnetic resonance imaging (μMRI) at 9.4 Tesla (T) was explored to examine osteochondral repair ex vivo in a preclinical large animal model. A specific aim of this study was to detect recently described alterations of the subchondral bone associated with cartilage repair.

Methods: Osteochondral samples of medial femoral condyles from adult ewes containing full-thickness articular cartilage defects treated with marrow stimulation were obtained after 6 month in vivo and scanned in a 9.4 T μMRI. Ex vivo imaging of small osteochondral samples (typical volume: 1-2 cm(3)) at μMRI was optimised by variation of repetition time (TR), time echo (TE), flip angle (FA), spatial resolution and number of excitations (NEX) from standard MultiSliceMultiEcho (MSME) and three-dimensional (3D) spoiled GradientEcho (SGE) sequences.

Results: A 3D SGE sequence with the parameters: TR = 10 ms, TE = 3 ms, FA = 10°, voxel size = 120 × 120 × 120 μm(3) and NEX = 10 resulted in the best fitting for sample size, image quality, scanning time and artifacts. An isovolumetric voxel shape allowed for multiplanar reconstructions. Within the osteochondral unit articular cartilage, cartilaginous repair tissue and bone marrow could clearly be distinguished from the subchondral bone plate and subarticular spongiosa. Specific alterations of the osteochondral unit associated with cartilage repair such as persistent drill holes, subchondral bone cysts, sclerosis of the subchondral bone plate and of the subarticular spongiosa and intralesional osteophytes were precisely detected.

Conclusions: High resolution, non-destructive ex vivo analysis of the entire osteochondral unit in a preclinical large animal model that is sufficient for further analyses is possible using μMRI at 9.4 T. In particular, 9.4 T is capable of accurately depicting alterations of the subchondral bone that are associated with osteochondral repair.

No MeSH data available.


Related in: MedlinePlus