Femoral head osteonecrosis: detection and grading by using a rapid MR imaging protocol.
OBJECTIVE
To design and evaluate a limited magnetic resonance (MR) imaging examination that can be performed rapidly and potentially inexpensively in patients with clinical suspicion of osteonecrosis.


METHODS
Both a limited and a full hip MR examination were performed prospectively in 179 hips in 92 patients with clinical suspicion of femoral head osteonecrosis. The presence of osteonecrosis was determined by two radiologists. The percentage of involvement of the femoral head weight-bearing surface was evaluated subsequently for osteonecrosis-positive hips on both sets of images.


RESULTS
Both examinations were performed successfully in all cases. Agreement between the limited and full examinations for presence of osteonecrosis was 98.9% (177 of 179 cases; kappa, 0.97). Forty-six (92%) of 50 patients with femoral head osteonecrosis at both examinations were placed in the appropriate quartile of percentage of femoral head weight-bearing surface involvement by both readers (weighted kappa, 0.94). Incidental findings were made at the full examination that could not be made or were difficult to make at the limited examination.


CONCLUSIONS
There was excellent agreement between the full and screening MR examinations for both detection of and determining the extent of osteonecrosis. The time and potential cost reduction achieved with a limited examination may allow introduction of MR imaging earlier in the diagnosis of femoral head osteonecrosis, as well as its more widespread use in patient care.
Khanna
A J
AJ
Departments of Orthopaedic Surgery, Division of Arthritis Surgery, and Radiology and Radiological Science at Good Samaritan Hospital, The Johns Hopkins Medical Institutions, MRI 143, 600 N Wolfe St, Baltimore, MD, USA.
Yoon
T R
TR
Mont
M A
MA
Hungerford
D S
DS
Bluemke
D A
DA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005271:Femur Head Necrosis / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016474:Weight-Bearing