To demonstrate the benefits of high-resolution multi-planar MRI PD-Fat-Sat sequences in diagnosing rectus femoris enthesopathy at its acetabular insertion. Raise awareness of this uncommon location of enthesopathy and include it in a diagnostic checklist when assessing MR studies in patients with sero-negative arthropathies.

Enthesopathy affects most ligament, capsular, tendon and fasciae insertions into bones. In the upper limb, it commonly arises in the supra-spinatus tendon and extensor tendons of the forearm inserting in the elbow. In the lower limb, enthesopathy commonly affecets the gluteal tendon insertions in the trochanteric region, patella tendon insertions in the tibia and lower pole of the patella, Achilles tendon and plantar fascia insertions into the os calcis. The spinal and sacro-iliac joint ligaments are also frequently affected by enthesopathy. Enthesopathy elsewhere in the...

On high-resolution PD-Fat Sat MR sequences, we were able to demonstrate often subtle but symptomatic enthesopathy of the rectus femoris tendon at its acetabular insertion. This was associated with mild osteitis in patients with known sero-negative arthropathies. This is seen as consistently high signal intensity on the PD-Fat Sat sequences in the antero-superior acetabular region, at the insertion of the direct and indirect heads of the rectus femoris tendons. Mild oedema in the adjacent muscle at the myo-tendinous junction can be present as well. Radiological...

High resolution, multi-planar PD-Fat Sat MR sequences can accurately demonstrate often subtle, but symptomatic enthesopathy of the rectus femoris tendon at its acetabular insertion, associated with mild-peri-lesional osteitis in patients with confirmed sero-negative arthropathies. Careful inspection and the inclusion of the tendon and fasciae insertions in the bone on a diagnostic check list, when assessing MRI studies, is important for diagnostic accuracy.

1) Bortolotto et al; Enthesitis of the Direct Tendon of the Rectus Femora Muscle in A Professional Volleyball Player: A Case Report. Journal of Ultrasound, June 2011, 14(2):95-8. 2) J Carreiro; Paediatric Manual Medicine, 2009. 3) McGonagle & Benjamin; Rheumatology (6th Edition) 2015.

Dr M.Ho is Radiolgy Registrar Belfast Acute Hospitals NI Dr C. Ming is Senior Registrar in Rheumathology in Kings College Hospital NHS Foundation Trust Dr S. Ahmed is Consultant MSK Radiologist at the Royal London/ Whipps Cross NHS Foundation Trust Drs A. Arora, L. Meacock and G. Constantinescu are Consultants MSK Radiologists in Kings College Hospital NHS Foundation Trust