| Background and objective:The early lesion of Ankylosing Spondylitis appears as sacroiliac joint cartilage anomaly. Sacroiliac joint is located in deep position with complex anatomical structure. Plain radiographs and CT can not display changes in articular cartilage. Although MRI can demonstrate, but general sequence imaging for cartilage is ineffective. However, articular cartilage is very thin, in low-spatial resolution of MRI, thus in order to enhance the detection capability of MRI as to the cartilage lesion, It is very important to optimize MRI sequence. By means of comparing multiple imaging sequences of Sacroiliac joint, this research is to seek out the ideal one as reference for examation of SIJ inflammation caused by AS.Materials and methods:1. Clinical research subject.The author focuses on 30 cases diagnosed with ankylosing spondylitis patients and 25 healthy volunteer in January 2009 to January 2010 period. Among the subjects, there are 26 male patients and 4 female patients with a female-to-male ratio 6.5:1 at ages from 18 to 39 years old, averaging 26 years old. Among 25 healthy volunteers, there are 14 males and 11 females, aged 19-36 years old. The 30 patients accords with Dr Van Der's New York clinical criteria for ankylosing spondylitis in 1984.2. Imaging methods1 X-ray&CT:The 30 patients have been recently under inspection through X-ray pelvis plain film. As to CT, the researcher conducted 5mm-thickness-and-5mm-pitch plain axial scan with Prospeed Spiral CT machine. 2:Conventional MRI imaging:The researcher used the spine coil and superconductive MRI,1.5T machine ESSENZA produced by the Siemens. The 30 patients and 25 healthy volunteers underwent MRI multiple sequence scanning of oblique coronal and conventional sequence axial scanning. The slice thickness defines as 3-4mm, separately by SE (T1WI and T2WI), TSE (T2WI) and SFS. The Patients and healthy volunteers were in supine position, the body median sagittal in line with the midline of long axis of the bed. Scanning sequence and parameters are the T1-se-tra-fil (TR 500ms, TE 11ms, thk4.0,512* 512), T1-tse-tra-320-fil (TR150 TE12 4.0thk 512* 416), T1-tse-cor-fil (TR400 TE12 4.0thk 576*768), T2-tse-tra (TR4000 ms, TE 89 ms,4.0thk,512*400), fat-suppressed sequence (SFS) including T2-tse-sfs-tra-fil (TR4090 TE824.0thk 768*528) and T2-tse-sfs-cor-fil (TR 4120 ms, TE 81 ms 4.0thk 640*480).3.MR cartilage imaging:The 30 patients and 25 healthy volunteers underwent sequence scanning of T1-flash 3D-water-cor-fil (TR 16.8 ms, TE 6.4 ms 1.2thk 384* 512), the T1 of water to stimulate T1-se-cor-water-FIl (TR450 ms, TE 11 ms 3.0thk, 512*512), T2-me2d-cor (TR 800 ms, TE 23ms 3.0thk 512*512) and T2-me3d-cor (TR 39ms, TE 22ms 1.2 thk 512*512).4. Diffusion-weighted imaging:The 30 patients and 25 healthy volunteers underwent sequence scanning of ep2d-diff-b200-400-600-128(TR2600 ms, TE 91 ms 4.0thk 128*128) andep2d-diff-b200-400-600-128-ADC (TR 2600 ms, TE 91ms 4.0thk 128*128).3. Image Evaluation:Imaging information was double-blind read films by two experienced radiologists, analyzing imaging manifestation of 30 patient's articular cartilage in various sequences and observed both sides of the articular surface of the adjacent bone structures, bone marrow edema and fat deposition. At the end, they compared degrees of displacement of 25 healthy volunteers'articular cartilage in various sequences4. Signal measurement After measuring signal intensity of cartilage, cortex and bone marrow etc in each scan sequence, the researcher calculated the signal intensity ratios and differences of healthy volunteers'sacroiliac joints in different sequences and of other structures5. Statistics ProcessingDuring Statistics Processing the researcher used SPSS 11.5 and Microsoft excel 2003 software; all count data are used in the form of q test because q test applies to comprehensive comparison between multiple samples; statistically, P=0.05 serve as the significance standard.Results:1,MRI Representations of normal healthy volunteers:General sequence of cartilage can be seen, but vague. Normal sacroiliac joint cartilage signal is classified as medium signal. The articular cartilage and the two-sided bone cortex on articular surface of sacroiliac joint constitute weak signal-intermediate signal-weak signal parallel linear structure normally with average and continuous signal manifestation.①Tl-se-cor-water-fil sequence cartilage showed clearly in all subjects. Among25 healthy volunteers,23 patients showed Iliac lateral cartilages, sacrum side cartilageand joint space with between them, in form of five parallel linear structure made up of Iliac lateral cartilages, sacrum side cartilage,and joint space them, bone cortexes both sides of the articular surface;②T2-me2d-cor sequences show clear cartilage in all subjects.20 cases appeared the iliac side of the sacral side of the cartilage and the joint space between them, which with both sides of the articular surface of cortical bone forms five linear structure. Articular cartilages of 5 cases shows clear, but no clear distinguish between Iliac lateral cartilages and sacrum side cartilage;③Cartilage signal appears bright, clear in all T1-flash-3D-water-cor-fil sequence subjects, which has clear boundaries between the surrounding the bone cortexes and marrow;④In T2-tse-sfs-cor-fil,8 cases of articular cartilage showed clear,22 cases of mixed signal articular cartilage,17 cases of articular cartilage irregular thickening, tortuosity,28 patients varying degrees of articular cartilage limited interruption, deletion, show some level of confusion, unilateral bone marrow edema in 18 cases,7 cases of bilateral bone marrow edema in 5 cases with no significant bone marrow edema;⑤T2-tse-sfs-cor-fil sequence of cartilage and bone cortex show relatively clear contrast.The signal intensity is weaker than the same level of bone. Cartilage with clearer boundaries between marrow, and bone cortexes;⑥T1-tse-tra-320-fil show more consistent three-tier structure and anatomy, but lower spatial resolution, (Figure 19).2. MRI Representations of patients:the 30 patients'sacroiliac joint area shows varying degrees of damage in previously normal three-tier structure, cartilage-line image thickening tortuous, signals on both sides of joints unevenly going down, bone cortex breaking up and depressing. Meanwhile bone changes parts and articular cartilage abnormalities are apt to overlap.In 30 cases of conventional sequence of,13 cases showed vague articular cartilages,17 cases showed mixed articular cartilage signals and irregular tortuous thickening of articular cartilage in 15 cases,24 patients have articular cartilage limited degree of interruption, deletion, fuzzy in partial levels.①In Tl-tse-tra-320-fil series,11 cases showed articular cartilage unclearly,19 cases of articular cartilage signal mixed, irregular thickening of articular cartilage in 14 cases, tortuous,23 patients varying degrees articular cartilage disruption, deletion;②In T1-tse-cor-fil sequence,10 cases showed unclear articular cartilage,20 cases of articular cartilage signal mixed, irregular thickening of articular cartilage in 15 cases, tortuous,24 patients have different articular cartilage limited degree of interruption, deletion, some level of confusion;③In T2-tse-sfs-tra-fil,6 cases showed unclear cartilage is,24 cases of articular cartilage signal mixed, irregular thickening of articular cartilage in 16 cases, tortuous,28 patients of varying degrees of articular cartilage interruption, deletion, displayed some levels of confusion, unilateral bone marrow edema in 18 cases, bilateral bone marrow edema in 7 cases of and no significant bone marrow edema in 5 cases;④In T2-tse-sfs-cor-fil,8 cases of articular cartilage showed clear,22 cases of mixed signal articular cartilage,17 cases of articular cartilage irregular thickening, tortuosity,28 patients varying degrees of articular cartilage limited interruption, deletion, show some level of confusion, unilateral bone marrow edema in 18 cases,7 cases of bilateral bone marrow edema in 5 cases with no significant bone marrow edema;⑤In T1-se-cor-wafer-FIL series,28 cases have mixed signals with articular cartilage,22 cases of articular cartilage with irregular thickening, tortuosity,30 cases of varying degrees of limitation of articular cartilage disruption, partially clear;⑥In Tl-flash-3D-water-cor-fil articular cartilage signal sequence,29 cases of mixed articular cartilage,25 cases of irregular thickening of articular cartilage, tortuous,30 patients with varying degrees of articular cartilage interruption, deletion, partially unclear,1 case of articular cartilage of patients can not be displayed in the other sequence, but T1-flash-3D-water-cor-fil sequence can clearly display short strip of articular cartilage remaining within th the left sacroiliac joint space;⑦In T2-me2d-cor,19 cases of articular cartilage signal sequence mixed,21 cases irregular thickening of articular cartilage, tortuous,28 cases of varying degrees of articular cartilage limited interruption, deletion, partly or completely unclear manifestion,25 cases of coarse both sides of articular cartilage with visible jagged protrusions responding to articular cartilage signal;⑧In T2-me3d-cor articular cartilage signal sequence,19 cases are of mixed articular cartilage,23 cases of irregular thickening of articular cartilage and tortuous,28 cases of articular cartilage limited disruption missing, partly or completely unclear manifestation; 25 cases of articular cartilage on both sides of coarse, visible and articular cartilage signal rather jagged protrusions;⑨With ep2d-diff-b200,400,600 subjects, signal changes of articular cartilage appear unapparent, respectively22,19,19 with similar signal to adjacent cortical bone and bone marrow t. Only 24 patients (40%) showed intermittent joint cartilage thickening, higher or lower signal change. As the B value increases, the rate of cartilage signal and display go down;⑩In ep2d-diff-ADC,14 cases show higher cartilage signal, partially slightly thickened tortuously,16 cases unclear articular cartilage, yet displaying a higher signal. Conclusion:1. Different sequences show the signal definitions of sacroiliac joint cartilage are quite different.2. A variety of comparative study of imaging scanning sequence showTl-flash-3d-water-cor-fil and T1-se-cor-water-fil are superior to conventional SE, TSE sequences in the articular cartilage thickness measurements.In addition, T1-se-cor-water-fil and T1-flash-3d-water-cor-fil can manifest more clearly remnants of cartilage than other sequences.3. As far as signal changes inside sacroiliac joints and display of cartilage surface defects are concerned, T1-flash-3d-water-cor-fil,T2-me3d-cor-fil and T2-me2d-cor-fil are superior to conventional sequences. T1-flash-3d-water-cor-fil can clearly display new serrated pannus on both sides of sacroiliac joint cartilage.4. T2WI articular cartilage signals are weak, not suitable for evaluation of early cartilage defects.5. DWI sequence, due to the impact of artifacts, is not suitable for inspection of sacroiliac joint cartilage lesions. |
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