Published in:
01-12-2016 | Classics in Abdominal Imaging
The T2 shading sign
Published in: Abdominal Radiology | Issue 12/2016
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A tree in afternoon sunlight, brightly lit on one side, and darkly shaded on the other, provides an ideal metaphor for the “classic” T2 shading sign (Fig. 1). This sign describes the reduction in inherent intensity in an endometrioma when the lesion is imaged on T2-weighted relative to T1-weighted (W) magnetic resonance (MR) images (Fig. 2) [1]. T2 shading may appear as fluid–fluid levels, a gradient in signal loss (Fig. 2), or as a homogeneous loss of signal (Fig. 3) within a lesion, compared to T1W images [1]. The mechanism of T2 shading relies heavily on high concentrations of protein and iron produced by cyclical bleeding within the lesion [2]. These contents result in T2 shortening and signal loss, a historically distinctive MR feature of endometriomas in the differential diagnosis of ovarian masses [2].
Fig. 1
Tree in afternoon sunlight. Adopted from https://www.flickr.com/photos/raybouk/8711071288
Fig. 2
A Axial T1-weighted image (TR 6.94, TE 2.39) through the pelvis demonstrating a hyperintense left adnexal lesion (bold arrow). B Axial T2-weighted image (TR 4850, TE 97) of the same lesion demonstrating fluid–fluid levels and a gradient of loss of signal intensity of the internal contents of the lesion, the T2 shading sign, characteristic of an endometrioma (thin arrow). The high concentration of protein and iron within the lesion due to cyclical bleeding results in T2 shortening and loss of signal intensity on T2-weighted imaging
Fig. 3
A Axial T1-weighted image (TR 189, TE 4.76) through the pelvis demonstrating a homogeneously hyperintense left adnexal lesion in a different patient (bold arrow). B Axial T2-weighted image (TR 5120, TE 100) of the same lesion demonstrating homogeneous loss of signal, T2 shading sign, characteristic of an endometrioma (thin arrow)
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