Peripatellar synovitis: comparison between non-contrast-enhanced and contrast-enhanced MRI and association with pain. The MOST study.

PURPOSE: To assess the diagnostic performance of signal changes in Hoffa's fat pad (HFP) assessed on non-contrast-enhanced (CE) magnetic resonance imaging (MRI) in detecting synovitis, and the association of pain with signal changes in HFP on non-CE MRI and peripatellar synovial thickness on CE MRI. METHODS: The Multicenter Osteoarthritis (MOST) Study is an observational study of individuals who have or are at high risk for knee OA. All subjects with available non-CE and CE MRIs were included. Signal changes in HFP were scored from 0 to 3 in two regions using non-CE MRI. Synovial thickness was scored from 0 to 2 on CE MRI in five peripatellar regions. Sensitivity, specificity and accuracy of HFP signal changes were calculated considering synovial thickness on CE MRI as the reference standard. We used logistic regression to assess the associations of HFP changes (non-CE MRI) and synovial thickness (CE MRI) with pain from walking up or down stairs, after adjusting for potential confounders. RESULTS: A total of 393 subjects were included. Sensitivity of infrapatellar and intercondylar signal changes in HFP was high (71% and 88%), but specificity was low (55% and 30%). No significant associations were found between HFP changes on non-CE MRI and pain. Grade 2 synovial thickness assessed on CE MRI was significantly associated with pain after adjustments for potential confounders. CONCLUSION: Signal changes in HFP detected on non-CE MRI are a sensitive but non-specific surrogate for the assessment of synovitis. CE MRI identifies associations with pain better than non-CE MRI.

A comparison of dedicated 1.0 T extremity MRI vs large-bore 1.5 T MRI for semiquantitative whole organ assessment of osteoarthritis: the MOST study.

OBJECTIVE: To date semiquantitative whole-organ scoring of knee osteoarthritis (OA) relies on 1.5 Tesla (T) Magnetic resonance imaging (MRI) systems. Less costly 1.0 T extremity systems have been introduced that offer superior patient comfort, but may have limitations concerning field-of-view and image quality. The aim of this study was to compare semi-quantitative (SQ) scoring on a 1.0 T system using 1.5 T MRI as the standard of reference. METHODS: The Multicenter Osteoarthritis Study (MOST) is a longitudinal study of individuals who have or are at high risk for knee OA. A sample of 53 knees was selected in which MRI was performed on a 1.0 T extremity system as well as on a 1.5 T scanner applying a comparable sequence protocol. MRIs were read according to the Whole Organ Magnetic Resonance Imaging Score (WORMS) score. Agreement was determined using weighted kappa statistics. Sensitivity, specificity and accuracy were assessed using the 1.5 T readings as the reference standard. In addition the number of non-readable features was assessed. RESULTS: Agreement (w-kappa) for seven main WORMS features (cartilage, bone marrow lesions (BMLs), osteophytes, meniscal damage and extrusion, synovitis, effusion) ranged between 0.54 (synovitis) and 0.75 (cartilage). Sensitivity ranged between 68.1% (meniscal damage) and 88.1% (effusion). Specificity ranged between 63.6% (effusion) and 96.4% (BMLs). Although the overall rate of non-readable features was very low, it was higher for the 1.0 T system (1.9% vs 0.2%). CONCLUSIONS: Semiquantitative whole organ scoring can be performed using a 1.0 T peripheral scanner with a moderate to high degree of agreement and accuracy compared to SQ assessment using a 1.5 T whole body scanner. Our results are comparable to the published inter- and intra observer exercises obtained from 1.5 T systems. Sensitivity to change of longitudinal scoring was not evaluated in this cross-sectional design and should be investigated in future validation studies.

Lumbosacral nerve root avulsions: MR imaging demonstration of acute abnormalities.

Most of the previously reported lumbosacral nerve root avulsions presented with pseudomeningoceles at the time of delayed initial imaging. We report a case of traumatic lumbosacral nerve root injury associated with an isolated femur fracture and demonstrate the evolution of pseudomeningoceles following nerve root avulsions and edema in the perineural fat identified on the initial MR imaging.

Entrapment of the acetabular labrum following reduction of traumatic hip dislocation in a child.

In traumatic hip dislocation, concentric reduction can be prevented by various causes. Soft-tissue interposition, such as entrapment of the acetabular labrum, is a rare but important cause of failed reduction of a hip. Early diagnosis of incomplete reduction due to interposition of soft tissue is important, because delayed treatment is associated with a greater incidence of avascular necrosis of the femoral head and early onset of osteoarthritis. This report describes a case of acetabular labral entrapment following reduction of traumatic hip dislocation in a child. The importance of CT and MRI in arriving at an early diagnosis is emphasized.

MDCT of tendon abnormalities using volume-rendered images.

OBJECTIVE: Our objectives were to report tendon abnormalities diagnosed on 3D volume-rendered images from MDCT data and to validate the clinical usefulness of this technique. CONCLUSION: We present 18 tendon abnormalities from 16 patients that were diagnosed on 3D volume-rendered MDCT images generated by commercially available software. Certain abnormalities such as avulsions, partial tears, and dislocations of tendons are clearly shown by this technique. This technique may prove useful in the evaluation of tendon abnormalities when MRI or sonography cannot be used.

T1-weighted MR imaging for distinguishing large osteolysis of Paget's disease from sarcomatous degeneration.

OBJECTIVE: To report five symptomatic patients, four with unequivocal Paget's disease and large areas of osteolysis and one patient with presumed osteolytic Paget's disease, evaluated by MR imaging to confirm or exclude a sarcoma. DESIGN AND PATIENTS: Four men and one woman (median age 74 years) presented with new symptoms of pain. Four of these patients had unequivocal Paget's disease with large areas of osteolysis; one patient presented with large focal osteolysis and no other finding. MR imaging was performed in each case to exclude malignancy in the area of osteolysis. RESULTS: Two patients whose MR images showed a low signal abnormality on the T1-weighted sequence corresponding to osteolysis on the radiograph were found to have malignant degeneration. Three patients with osteolytic lesions on T1-weighted MR imaging showed preservation of fat signal in the areas of osteolysis, were not biopsied and have been free of malignant disease for from 12 months to 2 1/2 years. One patient had one area of osteolysis in the iliac bone which showed malignancy and another area of osteolysis which showed preservation of fat signal on the T1-weighted sequence. CONCLUSIONS: The information obtained from T1-weighted MR imaging sequences performed on patients with Paget's disease who have new symptoms and large areas of osteolysis could reliably be used in the clinical decision-making process between conservative follow-up and biopsy.

Focal fibrocartilaginous dysplasia: curettage as an alternative to conservative management or more radical surgery.

We describe two cases of focal fibrocartilaginous dysplasia, one treated conservatively while the other underwent curettage of the lesion. Resolution of tibia vara and healing of the focal fibrocartilaginous dysplasia was noted at 6 months in the patient who underwent curettage while the conservatively managed patient required 8 years of follow-up. Of the 17 cases of conservatively followed tibial focal fibrocartilaginous dysplasia described in the literature, 11 showed complete recovery after a median interval of 57 months. We believe that curettage may result in rapid healing by removing the persistent mesenchymal anlage which can interfere with the normal growth of the tibia.