Subchondral high T2 signal in pediatric sacroiliac joint MRI : a normal finding that can mimic sacroiliitis
Notice bibliographique
Résumé
O044 Subchondral high T2 signal in pediatric sacroiliac joint MRI: a normal finding that can mimic sacroiliitis N. Herregods1 , L. B. Jans1 , M. Chen1 , T. Renson2 , J. Dehoorne2 , R. Joos2 , R. G. Lambert3 , J. Jaremko3 1 Radiology and Nuclear Medicine;2 Pediatric Rheumatology, Ghent University Hospital, Ghent, Belgium, 3 Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Canada Correspondence: N. Herregods Pediatric Rheumatology 2020, 18(Suppl 2):O044 Introduction: Understanding of the normal magnetic resonance imaging (MRI) appearance of the developing sacroiliac joint (SIJ) is important for distinguishing normal developmental variations from disease. Subchondral signal changes in SIJ in children can give rise to diagnostic challenges and false positive diagnoses of sacroiliitis, as they can mimic bone marrow edema (BME). Objectives: To determine how subchondral signal intensity on T2- weighted images in SI-joints in children varies with age, sex and closure of segmental apophyses of the sacrum. Pediatric Rheumatology 2020, 18(Suppl 2):83 Page 23 of 115 Methods: MRI of 502 SIJ in 251 children (132 girls), mean age 12.4 years (range 6.1-18.0), were obtained. Ethics committee approval was obtained, informed consent was signed by all children and parents. 127/251 had asymptomatic joints and were imaged for nonrheumatologic reasons in whom we added semi-coronal T1 and STIR of the SI joints, and 124 had low back pain but no sign of sacroiliitis on initial clinical MRI review. Before the main reading exercise, images of 10 participants (20 SIJ) who had been excluded from the study were used for multi-step calibration exercises. Three calibration rounds were conducted over 8 months. Subchondral high signal (‘flaring’) was defined as increased signal in subarticular bone on STIR images compared to normal bone marrow in the centre of S1 and S2 vertebral bodies. After calibration, three subspecialist radiologists independently scored subchondral signal changes from 0-3 in 4 locations: vertical sacral (along the lateral apophyses of the sacrum), horizontal sacral (along the intersegmental apophyses), iliac (vertically along iliac side of SIJ), and iliac crest (horizontally along iliac wing upper margin), separately for left and right sides. The degree of closure of sacral segmental apophyses was graded as well. Readers were blinded to demographic, clinical and other imaging findings. Associations between patient age, sex, signal changes and apophyseal closure were analysed. Results: Rimlike subchondral increased T2 signal or ‘flaring’ was commonly seen in children at the margins of the SI joints, and is far more common on the sacral side (72% vs 16%, p<.001). It was symmetrical in >90% of children. Iliac flaring scores were always lower than sacral, except for 1 child. Signal changes decreased as sacral apophyses closed, and were seen in <20% of subjects with fully closed apophyses. Signal changes were more frequent in boys, and peaked in intensity later than for girls (ages 8-12 vs. 7-10). Subchondral signal in iliac crests was high throughout childhood and did not correlate with other locations. We found no significant difference between left/right side, boys/girls nor between both groups. Conclusion: Rimlike subchondral high T2 signal 'flaring' is commonly observed at MRI of sacroiliac joints in children, and should not be confused with pathology. It is generally sacral-predominant, symmetrical, and seen in less than 1/5 of children after segmental apophyses are closed. Flaring that is asymmetrical, greater in ilium than sacrum, or intense in a teenager with closed apophyses, is unusual for normal children and raises concern for pathologic bone marrow edema. Subchondral signal in iliac crests is high throughout childhood and cannot be used for reference in diagnostic criteria. Accurately distinguishing between normal and pathologic pediatric subchondral sacroiliac joint signal changes requires understanding the patterns of normal variation, to avoid misdiagnosis of sacroiliitis. Disclosure of Interest None declared
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,003 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».