Role of T2*cartilage mapping in early detection of chondral lesions and its comparison with routine MR sequences

Objective • To evaluate role of T2*cartilage mapping in early detection of chondral lesions before they are detected on conventional morphologic sequences(fat saturated proton density sequence) • To compare T2* Cartilage mapping with routine MR sequences (FSPD ) Materials and Methods: This prospective study was done on 100 cases who underwent MRI knee,in which FSPD images were compared with the T2* maps. A Pilot study of 10 normal (young asymptomatic)subjects was done initially to define range and mean of normal values and artifacts. A sub study of 15 cases was also done comparing FSPD images, T2* maps with arthroscopy, to determine relative accuracy of either technique against the gold standard of arthroscopy. Clinical history of patients was taken before examination. MRI was performed with a Siemens AvantoMagnetom 1.5 TESLA MR scanner with dedicated phased-array receive-only knee coils. The patient was placed in the supine position with the knee placed within knee coil in neutral position. MR images were systematically obtained without administration of contrast material. Results: The range of normal T2* values determined from pilot study on normal subjects was 20-26.60 Msec. The mean T2* value of patellar and trochlear cartilage was found to be 24.30 + 3.8msec and this value was taken as reference normal T2* value. On comparison of corresponding T2* map and FSPD images in patellar and trochlear quadrants, overall complete match of chondral lesions was found in 65.30% of quadrants, no match was found in 30.50% of quadrants, partial match was found in 3.80% of quadrants, partial match reverse was found in 0.20 % of quadrants and no match reverse was found in 0.20% of quadrants. Conclusion: T2*cartilage mapping is sensitive to early cartilage changes and even changes not visible in high resolution MRI might be detectable with quantitative T2* cartilage mapping. It is more beneficial for detection of early chondral lesions/ changes in region of trochlear groove, lateral trochlear facet and patellar ridge areas where early lesions are more likely to be missed on conventional morphological sequences. T2* images were also found to be useful in the detection of early lesions in the mid third medial trochlear facet and upper third lateral patellar facet.