Introduction: T2 mapping is a quantitative magnetic resonance imaging method for
estimating knee cartilage damage degree. It is applied with various values of echo times. T2
map, presenting the spatial distribution of relaxation times, is calculated from series of T2
weighted images. Knee-joint articular cartilage and meniscus T2 relaxation time value reflect
the water content, collagen content, and collagen fiber orientation in matrix. Non-damaged
articular cartilage and meniscus have short T2 relaxation time. Increased T2 values are the
consequence of damaged tissue. T2 mapping data can be presented in a form of a color-coded
map. Purpose: The aim of this study was to define reference values of T2 relaxation time on
different regions of interest for non-damaged and damaged knee-joint cartilage and meniscus
for magnetic resonance scanner Philips Achieva 3.0 T TX. Methods: Twenty patients that
went through magnetic resonance knee scanning were chosen for our research. T2 mapping
pulse sequence in sagittal plane was added to basic pulse sequences in magnetic resonance
protocol for damaged knees. Data was processed with defining regions of interest on
parametric map in commercial program Intelli Space Philips. We measured T2 values on
anterior and posterior horn of medial and lateral meniscus in sagittal plane, and T2 values of
articular cartilage on patella, femur and tibia in sagittal plane. All values were arranged in
the table, and the statistical analysis was made. Results: T2 relaxation time of non-damaged
meniscus is 14,71 ms ± 1,5 ms, grade II 22,25 ms ± 0,97 ms and grade III 25,42 ms ± 3,34
ms. Average T2 relaxation time of non-damaged articular cartilage on patella is 37,30 ms ±
2,98 ms, but when this region is damaged the value increases to 56,42 ms ± 7,31 ms. T2
relaxation time of non-damaged knee-joint articular cartilage on femur is 40,49 ms ± 3,42
ms, while values of damaged cartilage on the same region increases to 59,23 ms ± 9,59 ms.
Average value of T2 relaxation time of non-damaged knee-joint articular cartilage on tibia is
23,37 ms ± 2,2 ms. Discussion and conclusion: T2 relaxation time of non-damaged tissues
varies due to its location. Non-damaged articular cartilage on tibia represents shorter T2
relaxation times compared to non-damaged articular cartilage on patella or femur.
Statistically important differences between values of T2 relaxation times between
non-damaged and damaged tissues were proven. T2 mapping pulse sequence is making
discovering early damage of meniscus and articular cartilage, and consequently applying
early treatment possible.
|