Oral Presentation at the European Congress of Radiology, Vienna, 2019

Purpose

To analyze the common pitfalls in T2 cartilage maps of the knee joint. To compare visualization of normal cartilage and chondral pathology on Fat Saturated Proton Density (FSPD) and T2 CartiGram by contrast ratio measurements.

Methods and Materials

The contrast ratio of weight-bearing and non-weight bearing cartilage was calculated on the CartiGram and FSPD images of 54 consecutive knee MRI scans performed on a 3.0 T MRI by selecting one slice each from the lateral and medial compartments and placing 3 ROIs on lateral and 2 on medial compartment. Mean of these T2 values was used to estimate contrast ratio of normal weight-bearing and non-weight-bearing segments on both sequences. The contrast ratio of the chondral lesions and the normal cartilage on both sequences was calculated. The pitfalls of Cartigram and additive value of FSPD were studied.

Results

The contrast ratio between weight-bearing and non-weight-bearing cartilage was statistically significantly higher (p < .05) on the CartiGram for normal cartilage. For chondral pathologies, contrast ratio difference was higher on FSPD images, but statistically insignificant (p = 0.91). The common pitfalls encountered on cartigram included 47 studies with joint capsule overlapping cartilage, 10 with cartilage fissures seen only on FSPD images, 28 with wider cartilage lesions on FSPD, 5 with synovial thickening.

Conclusion

Overlapping of joint capsule tissue with posterior femoral cartilage leads to a spurious assumption of intact femoral cartilage on Cartigram. Cartilage fissures and wider cartilage lesions are better seen on FSPD whereas smaller lesions better seen on T2 Cartigram.