| Objective:To explore the optimal scanning sequence and thus to evaluate the capability and limitation of MRI for normal adult lumbar zygapophyseal joint cartilage imaging,then further to offer visual and non-invasive radiographic examinations for the early diagnosis, follow-up observation, treatment and other clinical management of spinal column diseases.Methods:The right L4-5 lumbar zygapophyseal joints of 12 healthy adult volunteers were scanned through sagittal, transverse and coronal planes by Siemens 1.5 T MRI System with the body coils, while two bags of 100ml saline were placed behind the waist as references.The scan sequences were including:fast spin echo T1-weighted imaging (FSE T1WI), fast spin echo T2-weighted imaging (FSE T2WI), fat saturation proton density-weighted imaging (FS PDWI), three-dimensional fast low angle shot imaging (3D-FLASH), and water excitation three-dimensional fast low angle shot imaging (WE 3D-FLASH).All datas were measured by two doctors using double-blind method.Each scan sequence acquisitioned images from the same layer, and then the signal- noise ratio (SNR) for articular cartilage, contrast noise ratio (CNR) for cartilage versus bone cortex, cartilage versus bone marrow, cartilage versus saline and cartilage versus articular cavity in the Sagittal and transverse images were calculated.Results:1. Comparison of the four different flip angle(FA10°,FA 20°,FA 30°,FA40°)3D-FLASH sequences: The highest cartilage SNR,best CNR of cartilage versus bone cortex,and best CNR of cartilage versus bone marrow were found in the sagittal and transverse images in the 3D-FLASH(FA 10°) sequence, which were significantly different from the other three 3D-FLASH sequences.The articular cavities of the lumbar zygapophysieal joints couldn't be presented in all of the sagittal images, while, the cavities could be presented in the transverse images. The best CNR of cartilage versus articular cavity was found in the images in 3D-FLASH(FA 20°) sequence,and the worst was found in the 3D-FLASH(FA 10°) sequence.2. Comparison of the four different flip angle(FA 10°,FA 20°,FA 30°,FA 40°) WE 3D-FLASH sequences: The highest cartilage SNR, best CNR of cartilage versus bone cortex,and best CNR of cartilage versus bone marrow were found in the sagittal and transverse images in the WE 3D-FLASH (FA 10°) sequences, and the next were found in the WE 3D-FLASH (FA 20°) sequences. Both the WE 3D-FLASH (FA 10°) and WE 3D-FLASH (FA 20°) sequences were significantly different from the other two WE 3D-FLASH sequences. The articular cavities of the lumbar zygapophysieal joints couldn't be presented in all of the sagittal images, while, the cavities could be presented in the transverse images. The best CNR of cartilage versus articular cavity was found in the images in WE 3D-FLASH(FA 20°) sequence,and the worst was found in the WE 3D-FLASH(FA 10°) sequence.3. Comparison of seven sequences:The ranking of the values of the cartilage SNR and the CNR of cartilage versus bone cortex in descending order was in images in 3D-FLASH(FA 10°), WE 3D-FLASH(FA 10°), WE 3D-FLASH (FA 20°),3D-FLASH (FA 20°),FS PDWI, FSE T1WI and T2WI sequences. Both the 3D-FLASH and WE 3D-FLASH sequences displayed ideal cartilage SNR and CNR of cartilage versus bone cortex, they were significantly different compared with FS PDWI, FSE T1 WI and T2WI sequences.The ranking of the CNR values of cartilage versus bone marrow in descending order was in images in WE 3D-FLASH (FA 10°), WE 3D-FLASH (FA 20°),3D-FLASH (FA 10°),3D-FLASH (FA 20°), FSE T2WI, FSE T1WI and FS PDWI sequences.Both the 3D-FLASH and WE 3D-FLASH sequences displayed ideal CNR of cartilage versus bone marrow, they were significantly different compared with FS PDWI, FSE T1WI and T2WI sequences.The articular cavities of the lumbar zygapophysieal joints couldn't be presented in the sagittal and the transverse images in the FS PDWI,T1WI and T2WI sequences and couldn't be presented in the sagittal images in the 3D-FLASH and WE 3D-FLASH sequences, while, the cavities could be presented in the transverse images in the 3D-FLASH and WE 3D-FLASH sequences. The ranking of the values of the CNR of cartilage versus articular cavity in descending order was WE 3D-FLASH (FA 20°),3D-FLASH (FA 20°),3D-FLASH (FA 10°) and WE 3D-FLASH (FA10°) sequences,WE 3D-FLASH (FA 20°) sequence was significantly different from the other three sequences.4. Comparison of the sagittal, coronal and transverse images in the WE 3D-FLASH(FA 20°) sequence:The articular cavities of the lumbar zygapophysieal joints couldn't be presented in all of the sagittal and coronal images, while, the cavities could be presented in the transverse images.Conclusions:The comparative study on the multi-sequences of the normal adult L4-5 lumbar zygapophysieal joint cartilage MR images suggested that:3D-FLASH (FA 10°and FA 20°)Sequences and WE 3D-FLASH (FA 10°和FA 20°)sequences have advantage over the conventional sequences in terms of showing the lumbar zygapophyseal joint cartilages, we recommend them can serve for the lumbar zygapophyseal joint cartilage scanning.The MRI transverse scanning of the lumbar zygapophyseal joints can show the cavities, and its presentation of the lumbar zygapophyseal joint cartilage is superior to that of the sagittal and coronal scanning, therefore, we recommend that the transverse plane can serve as the first choice for the lumbar zygapophyseal joint cartilage scanning. |
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