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ObjectiveTo explore the different scanning sequences including conventional sequences and the emerging sequence along with comparison of signal-noise ratio (SNR) and contrast to noise ratio (CNR)and to evaluate capability and limitation of 1.5T MR imaging in right C5/6 intervertebral articular cartilage and surrounding anatomical structures (bone marrow, cortical bone).Materials and methods:Materials:12 healthy volunteers, Normal saline bag, Siemens 1.5T MRI system with cervical coils.Methods:Right C5/6zygapophyseal joints were scanned through sagittal plane using different pulse sequences. Two radiologists measured all the data using double blind method. Each scan sequence acquisitioned images in middle layer with the measurement of C5/6 articular cartilage and surrounding anatomy(bone cortex,marrow)along with normal saline and signal intensity(SI). Then SNR for articular cartilage, CNR for cartilage versus bone cortex, cartilage vs bone marrow,cartilage vs saline were calculated and compared.The sequences include:FSE T1WI, FSE T2WI, FS PDWI, and newer sequences EPI,3D-FLASH(FA10°, FA20°, FA30°, FA40°), WE 3D-FLASH (FA10°,FA20°, FA30°,FA40°)Results1. Comparison of the four different flip angle(FA10°,FA20°,FA30°, FA40°) 3D-FLASH sequences:The cartilage SNR and the CNR of cartilage-bone cortex and cartilage-bone marrow significantly higher for FA20°and FA 10°than other flip angles, but there was no statistical difference among FA 20°,FA 10°.The CNR of cartilage-normal saline of FA20°had highest and statistically significant value compared to FA10°。Comprehensive analysis showed the FA20°is better than other flip angles in Cervical cartilage imaging.2. Comparison of the Four different flip angle (FA10°, FA20°, FA30°, FA40°)WE 3D-FLASH sequence:The cartilage SNR,the CNR of cartilage-bone cortex and cartilage-bone marrow was highest in FA20° with significant statistical difference (P<0.05) when compared one by one with FA10°, FA30°, FA40°。The CNR of cartilage-normal saline was highest in FA20°with statistically significant difference between FA20°nd FA 10°,but there was no statistical difference among FA30°, FA40°.Comprehensive analysis showed the FA20°are better than other flip angles in Cervical cartilage imaging.3. Comparison of the 3D-FLASH (FA20°), WE 3D-FLASH (FA20°), EPI, FSE T1WI, FSE T2WI, FS PDWIsequences:The cartilage SNR of 3D-FLASH (FA20°) WE3D-FLASH (FA20°) and EPI were highest with no statistical significance when compared one by one in these 3 sequences, but there were significant statistical difference (p<0.05)when compared one by one with the FSE T1WI, FSE T2WI, FS PDWIsequences.The CNR of cartilage-bone cortex, cartilage-bone marrow of 3D-FLASH (FA20°) and WE 3D-FLASH (FA20°) were highest with no statistical significance between the 2 sequences when making comparison, but when compared one by one with EPI, FSE T1WI, FSE T2WI, FSPDWI sequences there were significant statistical difference(P<0.05). The CNR of cartilage-normal saline of FS PDWI sequences was highest in comparison with other 5 sequences subsequently FSE T2W had second largest value. FSE T1WI sequences for the CNR of cartilage-normal saline had lowest statistical value.Conclusion3D-FLASH and its derivatives WE 3D-FLASH, EPI sequence shows superiority over conventional sequences (FSE T1WI, FSE T2WI, FS PDWI) in cervical zygapophyseal joint cartilage scanning, however 3D-FLASH sequence and WE 3D-FLASH sequence is significantly better than the EPI sequence for Cervical articular cartilage and other inter-organizational structures (cortex, bone marrow), so it is recommended to check scanning sequence for small cervical articular cartilage. Comprehensive analysis showed 3D-FLASH sequence and WE 3D-FLASH sequence with flip angle of 20°showed better imaging of cervical articular cartilage with no significant difference between themselves. In addition the highest value of CNR for cartilage versus normal saline in FS PDWI sequences and FSE T2WI sequences will have certain advantages in the study of bone marrow edema or joint effusion.
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