International Journal of Clinical and Medical Imaging
Development and Testing of a Hybrid Synthetic-Biologic Phantom for the Optimization of Mr Sequences for Articular Cartilage
*Francesco Tessarolo Department Of Industrial Engineering, University Of Trento, Rome, Italy
*Corresponding Author: Francesco Tessarolo
Department Of Industrial Engineering, University Of Trento, Rome, Italy Email:email@example.com
Published on: 2018-11-08
Purpose To develop and validate a hybrid phantom for optimizing MRI sequences of knee articular cartilage. Methods in-vivo MR study of the knee was performed in two patients prior to total knee arthroplasty ( MR). Osteochondral surgical resections of femur and tibia were used to set-up a phantom consisting in a transparent polyethylene box filled with echographic gel. Phantom assemblage and in-vitro MRI was performed in one patient within 20 minutes after surgery (fresh MR) and, for the other patient, after having preserved the tissues in formalin for 12 months (post-fixation MR). Morphological sequences (SE T1-weighted, DESS, TRUFI 3D) and compositional maps (SE T2, GR T2*) were obtained on sagittal plane. Phantom was validated by comparing MR data obtained in-vivo and in-vitro. Comparison of data obtained from fresh and fixed tissues allowed also to assess modifications in MR signal due to formalin preservation. Results MR imaging in-vitro allowed the evaluation of the whole articular surface of the femoral condyles and tibial plateau. Excellent concordance existed between in-vivo and in-vitro cartilage morphology in T1-weighted images. DESS and TRUFI 3D sequences showed limitations for in-vitro MR imaging because of their sensitivity to magnetic field inhomogeneities. Formalin fixation preserved tissue morphology and T2 relaxation times of the chondral tissue. Conclusions The proposed hybrid synthetic-biologic phantom allowed obtaining in-vitro MR data super-imposable to in-vivo data for both fresh and formalin-fixed tissues, proving its usability for the optimization of knee cartilage MRI.
Magnetic Resonance Imaging; T2 mapping; Cartilage; Phantom
Magnetic resonance imaging (MRI) has proved to be an effective non-invasive diagnostic tool in the assessment of articular cartilage [1,2]. Accuracy of cartilage MRI has been improved in the last decade by developing cartilage specific sequences. The use of high-field magnetic resonance (MR) scanners with increased signal-to-noise ratio, allowed increasing spatial resolution and acquisition times [3-5]. Moreover, the development of new imaging techniques such as three-dimensional (3D) acquisition and spectral fat suppression  further increased diagnostic values of MRI.