Stefan Kirsch¹, Michael Kreinest², Gregor Reisig², and Lothar R Schad^1
1Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Germany, ²Department for Experimental Orthopaedics and Trauma Surgery, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany

In this study, single-slice ¹H mapping of ultrashort T₂ and T₂* was performed on porcine menisci. The signal decays were analyzed using a monoexponential, biexponential, and a Gaussian-exponential fit function. The quality of the curve fits was estimated and visualized by calculating the reduced chi-squared (²_red, “goodness of fit”) for each pixel. Areas with different type of signal decay were identified. Analysis of the parameter maps suggests that these areas can be assigned to regions with different collagenous texture. In future, in-vivo mapping of ultrashort T₂*/T₂ may provide a tool for early detection of tissue degeneration of menisci.

Min-Sun Son¹, Marc Levenston², Brian Hargreaves³, Weitian Chen⁴, Stuart Goodman⁵, and Garry Gold^6
1Bioengineering, Stanford University, Stanford, CA, United States, ²Mechanical Engineering, ³Radiology, Stanford University, ⁴GE Healthcare,⁵Orthopaedic Surgery, Stanford University, ⁶Radiology

T1ρ and T2 values from different regions of degenerated meniscal specimens were obtained using 3D MAPSS sequence with short echo times. Proteoglycan and collagen content and different mechanical properties were additionally measured for those regions. While regional patterns of the T1ρ and T2 did not match those of the extracellular matrix composition or mechanical moduli, T1ρ and T2 showed strong correlation with water and moderate correlation with mechanical properties. A strong, positive correlation between T1ρ and T2 was also found for all pooled regions despite the apparent lack of correlation between proteoglycan and collagen content. The findings in this study provide insight to understanding the physical meaning of T1ρ and T2 values.

Nian Wang¹, and Yang Xia^1
1Dept of Physics and Center for Biomedical Research, Oakland University, Rochester, Michigan, United States

To investigate the effects of mechanical strain and gadolinium (Gd) concentration on the quantitative determination of glycosaminoglycans (GAG) in articular cartilage, MRI T1 procedure was used to map the depth-dependent profiles of Gd and GAG in cartilage at 17.6µm pixel resolution. T1 in native tissue (without the presence of Gd ions) was both strain-dependent and depth-dependent. Compression reduced the tissue T1 when the Gd concentration was low, but enhanced the tissue T1 when the Gd concentration was high. The loading or loading history of patients should therefore be considered in any dGEMRIC-like procedure, if the GAG quantification is desired.

Jiang Du¹, Chantal Pauli², Won Bae¹, Martin Lotz², Graeme M Bydder¹, Darryl DLima², and Christine B Chung^1
1Radiology, University of California, San Diego, San Diego, California, United States, ²Scripps Clinic, San Diego, California, United States

 

Elli-Noora Salo^1,2, Mikko J. Nissi^2,3, Timo Liimatainen⁴, Shalom Michaeli³, Silvia Mangia³, Jutta Ellermann³, and Miika T. Nieminen^1,5
1Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland, ²Department of Applied Physics, University of Eastern Finland, Kuopio, Finland, ³Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, United States, ⁴Department of Biotechnology and Molecular Medicine, A. I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland, ⁵Department of Medical Technology, University of Oulu, Oulu, Finland

The purpose of this study was to compare various MRI parameters, (T₁, T₂, dGEMRIC index, T_1sat, continuous-wave T₁, adiabatic T₁ and T₂, and RAFF), after selective degradation of cartilage glycosaminoglycan and collagen. The MRI parameters exhibited different responses to the enzyme treatments: While native T₁ and the dGEMRIC index detected significant differences between control and glycosaminoglycan-depleted tissue, the majority of parameters showed a significant change after collagenase treatment. Significant correlations were observed between the MRI parameters and the biomechanical properties of the tissue, indicating MRI parameters as markers of the functional properties of cartilage.

Jose G Raya¹, Mike Notohamiprodjo², Svetlana Krasnokutsky³, Soterios Gyftopoulos³, and Christian Glaser^3
1Radiology, New York University Langone Medical Center, New York, New York, United States, ²University of Munich, ³New York University Langone Medical Center

In vivo DTI of articular cartilage has demonstrated high-diagnostic accuracy for OA in the patellar cartilage. Aim of this study was to demonstrate the feasibility and potential for diagnosis of in vivo DTI in all cartilage plates (patella, tibia lateral and medial and femur). DTI was performed sagittal on the right knee of 10 healthy volunteers and on 3 OA-diagnosed patients. MD and FA were measured on all cartilage plates. In the healthy population no difference in the diffusion properties among the cartilage plates was observed. OA subjects demonstrated abnormal diffusion properties in the patellofemoral and lateral tibiofemoral compartments.

Benjamin Schmitt¹, Goetz H Welsch², Moritz Zaiss³, Stefan Zbyn⁴, Sabine Goed⁴, and Siegfried Trattnig^4
1Centre for High-Field MR, Medical University of Vienna, Vienna, Austria, ²University Hospital Erlangen, ³German Cancer Research Center (dkfz),⁴Medical University of Vienna

This study presents initial results from gagCEST imaging performed on a clinical 3 T-MR scanner in 3 volunteers and 9 patients with focal knee injuries. In volunteers, the performance of a B0 correction method based on retrospective correction of z-spectra was evaluated by comparison with a standard phase mapping technique. Results from volunteers suggest applicability of the correction method and indicate that gagCEST effects can be measured at 3 T. Patient results show that gagCEST effects are susceptible to changes of T2 values, but could have a value for detection of GAG loss that occurs without affecting T2.

Guillaume Madelin¹, Gregory Chang², Alexej Jerschow³, and Ravinder R Regatte^2
1Radiology, New York University, New York, NY, United States, ²Radiology Department, New York University Medical Center, New York, NY, United States, ³Chemistry Department, New York University, New York, NY, United States

Quantitative sodium MRI is highly specific to the glycosaminoglycan content in cartilage and could be used to assess the biochemical degradation of cartilage in early stages of osteoarthritis (OA). In this preliminary study we show that quantitative sodium MRI with fluid suppression by adiabatic inversion recovery reduces significantly the partial volume effect from synovial fluids or joint effusion in the measurements of sodium concentrations in articular cartilage, and therefore may allow to better differentiate OA patients from healthy controls.

Jari Rautiainen¹, Mikko J. Nissi^1,2, Timo Liimatainen³, Walter Herzog⁴, Rami K. Korhonen¹, and Miika T. Nieminen^5,6
1Department of Applied Physics, University of Eastern Finland, Kuopio, Finland, ²Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, ³Department of Neurobiology, A.I. Virtanen Institute for Molecular Medicine, University of Eastern Finland, Kuopio, Finland, ⁴Faculty of Kinesiology, Engineering and Medicine, University of Calgary, Calgary, AB, Canada, ⁵Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland, ⁶Department of Medical Technology, University of Oulu, Oulu, Finland

The sensitivity of selected quantitative MRI parameters (Adiabatic T1ρ & T2ρ, continuous wave (CW) T1ρ, CPMG T2, Adiabatic double echo (DE) T2, T1 during off-resonance saturation, and relaxation along fictitious field (RAFF)) to early OA changes in rabbit anterior cruciate ligament transection model was investigated. Biomechanical testing of the samples revealed altered functional properties of the tissue in response to experimental OA, and a differential response to the various MRI methods was observed. Relaxation in the rotating frame of reference (continuous wave and adiabatic T1ρ and adiabatic T2ρ) proved to be most sensitive in detecting early cartilage degeneration.

Gregory Chang¹, Guillaume Madelin¹, Orrin Sherman², Eric J Strauss², Ding Xia¹, Michael P Recht¹, and Ravinder R Regatte^1
1Radiology, NYU Langone Medical Center, New York, New York, United States, ²Orthopaedic Surgery, NYU Langone Medical Center, New York, New York, United States

Use of a fluid-suppressed, adiabatic inversion recovery 3D radial sodium MRI pulse sequence at 7 Tesla may allow more accurate quantification of sodium content within cartilage repair.