Application of MR diffusion weighted imaging in the detection of early acute sacroilliitis / 中华放射学杂志

ABSTRACT

Objective To investigate the value of MR DWI in the detection of early acute sacroiliitis in patients with spondyloarthritis(SpA).Methods The data of sacroiliac joint MRI were retrospectively analyzed in fifty-nine patients with inflammatory low back pain and negative plain radiographs and/or CT.T1WI,T2WI,short tau inversion recovery (STIR) and DWI images were obtained in all cases.Contrast-enhanced T1WI with fat suppression (FST1WI) images were obtained in 28 patients and follow-up MRI examinations were performed during treatment in 7 cases.Acute inflammatory lesion was defined as hyperintense signal located in subchondral or periarticular regions on STIR images and or on enhanced FST1WI.Cases were divided into acute inflammation group and non-inflammation group.Comparison was performed among STIR,enhanced FST1WI and DWI in the detection of acute inflammation by using Chi-square test.Mean ADC value was obtained from normal and inflammatory areas in acute inflammation group and from subchondral bone marrow in non-inflammation group,and t test was used for comparison of ADC values.Results Acute inflammation existed in 38 cases (72 sacroiliac joints) and acute inflammatory lesions displayed as high signal on DWI in 35 cases (67 sacroiliac joints).STIR,enhanced FST1WI and DWI showed no significant difference in the detection of acute sacroilliitis (37/38,38/38,36/38,respectively;x2=0.16,P=0.923).ADC values measured from acute inflammatory areas were significantly higher than values measured from normal area in acute inflammation group [(1.087± 0.207)× 10-3 and (0.537±0.091) × 10-3mm2/s],and values measured from subchondral bone marrow in non-inflammation group [(0.487±0.112) × 10-3mm2/s],there were significant difference (t values were 14.971 and 12.289,P＜0.01).ADC values were similar between normal area in acute inflammation group and subchondral bone marrow in non inflammation group (t=1.874,P=0.066).ADC values were (1.018±0.266) × 10-3 and (0.706±0.164) ×10-3mm2/s before and after the treatment (t=5.312,P＜0.01).Conclusions DWI is a sensitive method to display acute inflammatory lesions in sacroiliac joints.ADC values can be effectively used to quantify inflammatory lesions in acute sacroilliitis as well as in the evaluation of efficacy of treatment.