3T MRI improves diagnosis, management of knee osteoarthritis

An exam that combines 3T MR imaging with clinical assessment could speed up the management of patients with suspected degenerative arthritis of the knee. Disease biomarkers could be identified in half the time than is currently possible or less, according to researchers.

Osteoarthritis affects at least 16 million patients in the U.S. annually, with the knee being the most commonly involved joint. Standard radiography and 1.5T MRI are the most common imaging studies performed to evaluate cartilage changes that characterize the condition, which may require up to two years from its genesis to diagnose with these techniques.

The development of 3T MRI and semiquantitative clinical assessment techniques could allow physicians to diagnose the disease sooner and more accurately evaluate multiple features relevant to the functional integrity of the knee, said principal investigator Dr. Sapna Jain, a radiology resident at the University of California, San Francisco.

Jain and colleagues prospectively assessed 20 patients with grade 2 and grade 3 osteoarthritis of the knee and 20 age-matched controls. Patients and controls underwent 3T MRI at baseline and at three, six, and 12 months. The investigators assessed eight structural imaging abnormalities related to the tibiofemoral condyle, patella, and trochlea. They correlated imaging data with three clinical parameters for the assessment of pain and mobility: the Western Ontario and McMaster Universities (WOMAC) index, the SF-36, and a standardized visual analog scale (VAS).

Three specific types of imaging abnormalities - bone marrow edema, cartilage morphology, and meniscal extrusion - showed a significant correlation with the clinical assessment and could help the short-term assessment of osteoarthritis evolution. Jain presented her group's findings at the 2007 RSNA meeting.

The researchers found structural imaging differences between controls and osteoarthritis patients at baseline and at one-year follow-up. Osteoarthritis patients showed cartilage changes in the medial and lateral femur and trochlea; a pattern of bone marrow edema in the medial tibia, trochlea, and lateral facet; and meniscal extrusion. Osteoarthritis patients also showed higher values in WOMAC, SF-36, and VAS scores compared with controls.

All differences were statistically significant (p<0.05). A significant positive correlation was found between changes in cartilage morphology and clinical scores in control patients but not in osteoarthritis patients.

"We found significant differences between osteoarthritis patients and controls with regards to MR imaging and clinical data. At 12-month follow-up, we see a significant change in cartilage and morphology of the tibiofemoral compartment in osteoarthritis patients, which we didn't see in normal controls," Jain said.

For more information from the Diagnostic Imaging archives:

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Osteoarthritis may signal faster biological aging