Comparison Between High-Resolution Isotropic 3D Cube PD-FS And Conventional 2D PD-FS MR Images Of The TFCC At 3.0T

Objective: Attempted to acquire conventional 2D proton density-weighted fat-suppression(PD-FS)and high-resolution isotropic 3D Cube PD-FS sequence imaging in healthy volunteers' wrist at 3.0T MRI.The post-processing and reconstruction of 3D Cube PD-FS images was performed on a vendor supplied software(AW4.6work station,GE)after the MR examination.To investigate the value of 3D Cube PD-FS sequence and 2D PD-FS in assessing TFCC of the wrist in term of image quality and diagnostic performance,so as to provide a non-invasive,scientific and timely MR scanning scheme for clinical patients with wrist joint scanning.Methods: A total of 35 wrists from 20 healthy volunteers(9 male and 11 female,aged18 to 27 years,average of 22.7 years)were enrolled in the study.All MR images were obtained using an 8-channel wrist coil on a 3.0T system.Each MRI examination was performed with the following sequences: coronal and sagittal 2D PD-FS,axial T2 FS and coronal isotropic 3D Cube PD-FS.Delineation of anatomic structures of the wrist(including the TFCC,scapholunate ligament,lunotriquetral ligament and cartilage),amount of artifact,quality of fat suppression,image blur and overall quality were subjective analysis using5-point scoring system.All viewers were blinded to the subject and sequence information.Subjective comparison of 2D PD-FS sequence and 3D Cube PD-FS sequence to the anatomy of the triangular fibrocartilage complex(TFCC)using a 5-point scoring system.The mean and standard deviation(SD)of signal intensity(SI)were determined for the disc of TFC,fluid,cartilage and bone marrow.The signal-to-noise-ratios(SNR)of each structure and contrast-to-noise ratios(CNR)between structure A to structure B was calculated using formula for direct quantitatively comparison of image quality between 2D PD-FS and 3D Cube PD-FS sequence.Data analysis using SPSS 22.0 statistical software,subjective measurements of three imaging techniques(2D PD-FS,3D Cube PD-FS and reconstructed 3D Cube PD-FS)were assessed by the Wilcoxon signed-rank test.Comparison of SNR and CNR between three sequences were assessed using one-way analysis of variance with a significance threshold of P<0.05.Inter-observer agreement to evaluate MRI for the visibility of anatomic structures was calculated using k statistics.Results:Inter-observer agreements: Inter-observer agreement for the visibility was the lowest(k value = 0.402)for the evaluation of fat suppression in 2D PD-FS.Inter-observer agreement for the visibility was the highest(k value=0.857)for the evaluation of lunotriquetral ligament in the reconstructed 3D Cube PD-FS.Subjective analysis: The 2D PD-FS MRI demonstrated higher scores than 3D Cube in anatomic structure of the ulnar attachment,radial attachment,meniscus homologue and cartilage.There were no statistical significance between 2D PD-FS and 3D Cube PD-FS in TFC(P=0.077),scapholunate ligament(P=0.104),lunotriquetral ligament(P=0.057),volar and dorsal radioulnar ligaments(P=0.929).There were significant differences in the remaining quantitative analyses,including artifact,image blur,fat suppression and overall quality between isotropic 3D Cube and conventional 2D PD-FS MRI(P<0.001).However,the 3D Cube reconstruction sequence in the aspect of lunate cartilage and image quality was similar to that of the 2D PD-FS sequence,but there were statistically significant difference.The TFC,radial attachment,volar and dorsal radioulnar ligaments and lunotriquetral ligament revealed no statistical significance between 2D PD-FS sequence and reconstructed 3D Cube(P>0.05).Objective analysis: The 2D PD-FS and reconstructed 3D Cube sequences showed significantly higher SNR of TFC,cartilage,fluid and bone marrow compared with 3D Cube,all of which showed significant statistical difference(P< 0.05).2D PD-FS and reconstructed3 D Cube had similar SNR values in TFC,cartilage,fluid and bone marrow.There were no significant difference in CNR of each structure between three groups.Conclusion:1.The subjective score of 3D Cube PD-FS sequence in TFCC,the SNR value and CNR value of imaging were lower than those of conventional 2D PD-FS sequence.However,reconstructed 3D Cube sequence were similar to 2D sequence of SNR value and CNR value.2.High-resolution 3D isotropic Cube PD-FS MR imaging of the wrist has better visibility for small structures of the TFCC than 2D PD-FS,because it has thin-layer scanning and arbitrary multi-plane reconstruction as well as reducing imaging time markedly.3.With regard to clinical applications,high-resolution 3D Cube PD-FS MR imaging ofthe wrist at 3.0T has almost equal potential to 2D MRI.3D Cube sequence is clinically feasible and can play an additional role in the diagnosis of TFCC integrity and clinical manifestation.