Can T2 relaxation values and color maps be used to detect chondral damage utilizing subchondral bone marrow edema as a marker?

This study aimed to investigate whether a commercially available time-efficient T2 mapping sequence will demonstrate findings of articular cartilage degeneration based on T2 relaxation values (RV) and color maps, using subchondral bone marrow edema (BME) as a marker for chondral damage. The patient group consisted of 88 subjects who underwent knee magnetic resonance imaging at 1.5 T who had subchondral BME evident on fat-suppressed T2-weighted sequences. The control group was comprised of 60 subjects with no evidence of subchondral BME. A commercially available eight echo T2 relaxation sequence (acquisition time 8:36 min) was used to construct a T2 color map and to determine T2 RVs. T2 RVs were determined on cartilage overlying subchondral BME in patients and in eight pre-determined anatomical regions in controls. T2 color maps in the patient and control groups were analyzed for degree of color stratification (presence = two or more colors) at the same anatomic site as that used for T2 RV determination. T2 RVs were significantly increased in patients compared to controls for the medial femoral condyle (MF; p < 0.01), medial patellar facet (MP; p < 0.01), lateral patellar facet (LP; p < 0.01), lateral femoral condyle (LF; p < 0.01) and lateral tibial plateau (LT; p < 0.01). Loss of color stratification was noted in patients compared to controls in the medial tibial plateau (MT; p = 0.01), LF (p < 0.01), and LT (p < 0.01). In the patient group, increase in T2 RVs was associated with corresponding decrease in color stratification in MF (p < 0.01), MT (p < 0.01), MP (p < 0.01), medial femoral trochlear groove (p = 0.02), and lateral femoral trochlear groove (p < 0.01). Subchondral BME was associated with an increase in adjacent articular cartilage T2 RVs at some sites. Also, elevated T2 RVs were associated with loss of color stratification.