| Purpose: To use T2value measurements and pseudo-color map based magneticresonance T2mapping sequence to detect early sacroiliac joint changes in patientswith ankylosing spondylitis.To investigate the value of T2mapping sequence in earlydiagnosis of ankylosing spondylitis.Subjects and methods:50patients (33male,17female) with chronic inflamatorylow back pain symptoms in Our hospital from September2011to April2012werecollected,out of which36patients were clinically diagnosed as AS (24male,12female) and the remaining14(9male,5female)as simple chronic low back pain(LBP).Images were obtained using a1.5T MR scanner HDxt GE and a Cardiacphased array coil. The sequences included oblique coronal STIR, axial FSE T1WIand FRFSE T2WI fat suppression sequences and8echo T2mapping sequence. Thedifference of the T2value in subchondral bone morrow of AS were compared withLBP patients, GE AW4.4post-processing workstation was employed to generate apseudo-color map, measuring T2values of subchondral bone morrow in bilateralilium and sacrum along the sacroiliac joint.An independent two sample t-test (SPSSVersion18) was used to statistically analyse the difference of T2values between ASand LBP patients with P value of <0.05as the level of statistically significantdifferent.Result: Subchondral bone morrow of36AS patients were measured with mean T2values (mean±standard deviation)（109.02±12.46） ms in the right ilium,(112.00±14.71) in the left ilium and（110.51±10.62）ms in bilateral ilium，versus（103.01±12.84）in the right sacrum，（101.84±11.63）in the left sacrum and（102.42±10.26）in bilateral sacrum，the mean T2value of14LBP patients weremeasured which were (102.04±6.1) in the right ilium，(104.41±7.57) in the left iliumand（103.23±6.75）in bilateral ilium，versus（101.59±5.01）in the right sacrum，(101.81±4.76) in the left sacrum，and（101.7±4.76）in bilateral sacrum.There was nostatistically significant difference between the AS and LBP group of the mean T2values in bilateral sacrum. The mean T2values in bilateral iliac bone marrow of ASpatients are higher than the LBP patients (p <0.05). There were26patients with a totalof52limitations of bone marrow edema (49in the bilateral ilium or sacrum,2inlumbar vertebra，1in the right ischium) in36AS patients and the majority of them with synovial thickening.. The other10had no obvious high signal on T2WI, one of them had bilateralsacroiliac joint fusion.12focal fat deposition (6in the right ilium,2in the rightsacrum, and4in the left ilium) were also found in them. We also found8limitationsof muscle edema near the L-spine and sacroiliac joint. The mean T2values of thebone marrow Lesion was (124.83±19.63)ms, which was higher than the neighboringrelatively normal bone marrow that the mean T2Value was (97.88±11.27)ms.（P=0.000）The mean T2values of muscle lesion was (96.36±7.54) ms, which ishigher than the neighboring relatively normal muscle tissue that the mean T2valuewas (57.97±7.97)ms.（p=0.002）Conclusion:T2mapping sequence could detect the early change of the mean T2values of bone marrow, by which early bone marrow lesions of ankylosingspondylitis could be detected and we could use this technology to differentiate simplechronic low back pain and AS patients so that we can make earlier diagnosis. |
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