探讨儿童化脓性骶髂关节炎(PS)的影像学表现及其临床辅助诊断价值。

选择2016年1月至2021年6月首都儿科研究所附属儿童医院收治的7例(患儿1~7)儿童PS患儿为研究对象。回顾性分析这7例儿童PS患儿的临床资料、X射线骶髂关节正位摄片、CT及MRI检查结果。本研究遵循的程序符合2013年修订的《世界医学协会赫尔辛基宣言》要求，并与受试对象监护人签署临床研究知情同意书。

①7例患儿年龄为6~14岁，男性患儿为4例，女性为3例，均为单侧骶髂关节受累。②仅患儿1的X射线骶髂关节正位摄片提示异常，为髂骨侧关节面毛糙。③CT检查结果显示6例(患儿1~3、5~7)可见关节面破坏、其中5例(患儿1~3、5、6)位于髂骨面，3例(患儿1、2、5)可见髂骨关节面下透亮区，3例(患儿1、2、7)见关节前软组织肿胀，2例(患儿1、7)出现关节间隙狭窄，2例(患儿2、7)行CT增强扫描，1例(患儿2)见脓肿形成。④MRI结果示，7例患儿均未见明确关节狭窄，其中6例(患儿2~7)可见关节间隙内脂肪抑制质子密度加权成像(FS PDWI)高信号影；5例(患儿1、2、5~7)可见关节面破坏；6例(患儿1、2、4~7)骶髂关节双侧关节面骨髓受累患儿中，仅1例(患儿7)以骶骨侧受累显著，余均以髂骨侧受累显著。4例(患儿2、5~7)出现软组织脓肿，FS PDWI表现弥漫高信号区内出现类圆形更高信号灶，边缘清晰，部分可见壁结构，增强后压脂T1加权成像(T1WI)图像中可见环形强化；4例(患儿1、2、5、6)可见关节周围淋巴结肿大征象。

儿童PS的临床表现与体征缺乏特异性、易被临床误诊。MRI检查对该病的辅助诊断具有较高灵敏度和特异度，可全面评估关节内炎症、关节面下骨髓水肿及周围软组织肿胀情况，对脓肿的检出率高，因此对儿童PS早期诊断可首选影像学检查方法。CT检查可清晰显示病变进展期的骨质变化，包括关节面骨质破坏和关节间隙狭窄，有助于判断该病患儿预后，可作为MRI检查的重要补充。

To investigate imaging features and clinical diagnostic value of pyogenic sacroiliitis (PS) in children.

A total of 7 children with PS admitted to Children′s Hospital, Captial Institute of Pediatrics from January 2016 to June 2021 were selected into this study. The clinical data, X-ray images result of sacroiliac joint, CT and MRI findings of these 7 PS children were analyzed retrospectively. The study was conducted in accordance with World Medical Association Declaration of Helsinki revised in 2013. Informed consent was obtained from each participate′ guardian.

① These 7 PS children aged from 6 to 14 years old, including 4 boys and 3 girls, were involved in unilateral PS. ②Only one case (children No.1) had an abnormality suggested by X-ray orthopantomogram of the coarse articular surface of iliac crest. ② CT images showed sacroiliac joint space narrowing in 2 cases (children No.1, 7) and articular surface destruction in 6 cases (children No.1-3, 5-7), 5 (children No. 1-3, 5, 6) of which were located in ilium surface. Euphotic zone under articular surface of iliac was seen in 3 cases (children No.1, 2, 5). In 3 cases (children No. 1, 2, 7), there was soft tissue swelling around sacroiliac joint. One (child No.2) of the 2 cases (children No.1, 2 ) performed enhanced CT showed abscess formation. ④The results of MRI showed that no definite sacroiliac joint stenosis was found in 7 children, and high signal shadow of fat-suppression protein density weighted imaging(FS PDWI) in sacroiliac joint space were seen in 6 children (children No.2-7), and 5 cases (children No.1, 2, 5-7) showed articular surface of sacroiliac joint destruction. Among 6 children (children No.1, 2, 4-7) with bone marrow involvement in bilateral articular surfaces of sacroiliac joint, only one child (child No.7) was located on sacrum side, and the rest were located on ilium side. Soft tissue of sacroiliac joint abscess occurred in 4 cases (children No.2, 5-7). FS PDWI of MRI showed that there was a round-like high signal focus in the diffuse high signal area, with clear edge and partial wall structure. After enhancement, annular enhancement of MRI could be seen in T1WI images, and 4 cases (children No.1, 2, 5, 6) showed signs of lymph node enlargement around sacroiliac joint.

The clinical signs of PS in children lack of specificity and can be easily misdiagnosed. MRI has high sensitivity and specificity to auxiliary diagnosis of PS, it can fully evaluate sacroiliac joint inflammation, bone marrow edema under the sacroiliac joint and soft tissue swelling of sacroiliac. It has high detection rate of abscess and it′s the first choice for early diagnosis of this disease, which is better than X-ray and CT. CT can show the bone changes in progressive stage of lesions clearly (including articular surface bone destruction and joint space stenosis), which is helpful to judge prognosis of children, and is an important complementary imaging method for MRI examination.