Abstract:

Objective〓[WTBZ]To explore the effects of different scan sequences and parameters on image quality, and to obtain the optimal different 3D-FSPGR parametersequences. [WTHZ]Methods〓〖WTBZ〗Three normal cadaver wrists were imaged with GE SIGNA EXITE II 3.0T MR system. SE T1WI, FSE T2WI, PDWI, FS PDWI and 3D-FSPGR were determined, and the 3D-FSPGR sequences were achieved by varying flip angles (5,10,20,30, 60°) and combining each flip angle with different echo time(TE) ［minimum(2.2ms), minfull(6.6ms), inphase(2.2ms) and outphase(3.2ms)］. This gave the same layer imaging parameters for each scan sequence. Then the contrast-to-noise(C/N) ratios for cartilage versus bone marrow and the cartilage versus tendon were calculated. 〖WTHZ〗Results〓〖WTBZ〗① The highest CNR and better SNR between cartilage and adjacent tissues were found in the 3D-SPGR T1［TE/minfull(6.6ms), Flip(30′)］ sequence； ② The SNR of articular cartilage was not statistically different among PDWI, FS PDWI and 3D-FSPGR sequences； CNR of articular cartilage with adjacent tissues in the 3D-FSPGR sequence showed significant differences compared with the PDWI and the FS PDWI sequences. There were no significant differences in all groups of 3D-FSPGR sequences； ③ In the SE T1WI and the FSE T2WI sequences, both (signal to noise ratio)SNR of articular cartilage and(contrast to noise)CNR between cartilage and adjacent tissues were decreased but significant differences were not found between them（P＞0.05）. Compared with the other sequences, SE T1WI and FSE T2WI sequences showed statistical significances. 〖WTHZ〗Conclusions〓〖WTBZ〗Among the five sequences, the optimal parameters are the 3D-FSPGR TE/flipl(6.6ms/30°) sequence. The sequences have significant advantages compared with the other series in imaging normal cartilage of the wrist, and the 3D-FSPGR sequence is the optimal sequence for assessment of cartilage. As a conventional scan sequence, FS PDWI sequence can do a good job in imaging articular cartilage.

Key words: Wrist joint, Cartilage, Magnetic resonance imaging, Parameters-optimization