Detection of inflammatory sacroiliitis in children with magnetic resonance imaging: is gadolinium contrast enhancement necessary?

Abstract

Objective: In adults, gadolinium contrast enhancement does not add incremental value to fluid-sensitive sequences for evaluation of bone marrow edema. This study was undertaken to determine if magnetic resonance imaging (MRI) contrast is necessary to assess lesions consistent with inflammatory sacroiliitis in children.

Methods: Patients with clinically suspected or diagnosed juvenile spondyloarthritis (SpA) underwent pelvic MRI consisting of multiplanar fluid-sensitive and postgadolinium T1-weighted fat-saturated sequences including dedicated sacral imaging. Three radiologists independently evaluated the fluid-sensitive sequences, and later, the complete study (including postcontrast images). With postcontrast imaging as the reference standard, we calculated the test properties of fluid-sensitive sequences for depiction of acute and chronic findings consistent with sacroiliitis.

Results: The 51 patients had a median age of 15 years, and 57% were male. Nineteen patients (22 joints) were diagnosed as having sacroiliitis based on postcontrast imaging, and none had synovitis in the absence of bone marrow edema. All 22 joints demonstrated bone marrow edema on both fluid-sensitive and postgadolinium T1-weighted fat-saturated sequences. Eighteen percent of joints with sacroiliitis had capsulitis, which was observed on both noncontrast and postcontrast imaging. Fifty-nine percent of joints with sacroiliitis had synovitis on postcontrast imaging. Sensitivity, specificity, positive predictive value, and negative predictive value of fluid-sensitive sequences for the detection of acute inflammatory lesions consistent with sacroiliitis using postgadolinium imaging as the reference standard were excellent. Interrater reliability was substantial for all parameters.

Conclusion: Our findings indicate that fluid-sensitive sequences are sufficient to detect acute and chronic lesions consistent with inflammatory sacroiliitis in children.

Figure 1. Active inflammatory lesions of the sacroiliac joints visible on both fluid-sensitive and post-contrast sequences

17-year-old male with left lower back pain. (A) Coronal oblique STIR imaging of the sacrum demonstrates bone marrow edema within the inferior periarticular aspect of right iliac bone (solid arrow). There is a small amount of joint fluid within the inferior aspect of the joint (arrowhead). A normal hyperintense subchondral stripe is seen on the left in this skeletally immature child (dashed arrow). (B) Coronal oblique T1 weighted post contrast imaging of the sacrum demonstrates enhancing bone marrow edema within the inferior right iliac bone (solid arrow) and adjacent synovitis within the inferior, ventral aspect of the joint (arrowheads) with adjacent periarticular enhancement which is greater on the iliac side. There is a normal, mild enhancement of the left segmental sacral apophyses (dashed arrow).

Figure 2. Active inflammatory lesions and normal findings in skeletally immature sacroiliac joints visible on both fluid-sensitive and post-contrast sequences

8 year-old male with right lower back pain. (A) Coronal oblique STIR imaging of the sacrum demonstrates periarticular bone marrow edema within the left sacrum and left iliac bone (solid arrows). There is a small amount of joint fluid within the left sacroiliac joint with adjacent capsular edema (arrowheads). There is edema at the gluteal muscle origin (dashed arrow). (B) Coronal oblique T1 weighted post contrast imaging of the sacrum demonstrates enhancing periarticular bone marrow (solid arrows), adjacent synovitis (circle) as demonstrated by periarticular enhancement within the inferior, synovial lined portion of the joint space, capsulitis (arrowheads) and enhancing inflammation at the gluteal muscle origin (dashed arrow).