Case Of the Week (COW) 14 July 2013
Answer:
The Shading Sign -Bilateral Endometriotic Cysts.
Findings:
Bilateral cystic lesions noted in both adnexae , appearing hyperintense in T1W1 as well as fat suppressed T1W1. The cysts appear hypointense in T2W1 with layering – SHADING SIGN The above two findings are consistent with diagnosis of Endometriotic(chocolate ) cysts.
Discussion:
The shading sign is a characteristic feature of endometriotic cysts (endometriomas) at MR imaging. The shading sign is the magnetic resonance (MR) imaging finding of T2 shortening in an adnexal cyst that is hyperintense on T1-weighted images. Endometriotic cysts are highly viscous and have a high concentration of protein and iron from recurrent hemorrhage. These components can shorten T2 and may contribute to signal intensity loss, described as shading . In addition, intra- and extracellular methemoglobin markedly shorten the T1 of fluids resulting in hyperintensity on T1-weighted images and hypointensity (shading) on T2-weighted images.
REF: The Shading Sign July 2002 Radiology, 224, 199-201.
Contributed By:
Dr. Babu Peter MD, DNB
Associate Professor, Barnard Institute of Radiology
Senior Consultant radiologist, Aarthi scans, Chennai
Answer:
The Shading Sign -Bilateral Endometriotic Cysts.
Findings:
Bilateral cystic lesions noted in both adnexae , appearing hyperintense in T1W1 as well as fat suppressed T1W1. The cysts appear hypointense in T2W1 with layering – SHADING SIGN The above two findings are consistent with diagnosis of Endometriotic(chocolate ) cysts.
Discussion:
The shading sign is a characteristic feature of endometriotic cysts (endometriomas) at MR imaging. The shading sign is the magnetic resonance (MR) imaging finding of T2 shortening in an adnexal cyst that is hyperintense on T1-weighted images. Endometriotic cysts are highly viscous and have a high concentration of protein and iron from recurrent hemorrhage. These components can shorten T2 and may contribute to signal intensity loss, described as shading . In addition, intra- and extracellular methemoglobin markedly shorten the T1 of fluids resulting in hyperintensity on T1-weighted images and hypointensity (shading) on T2-weighted images.
REF: The Shading Sign July 2002 Radiology, 224, 199-201.
Contributed By:
Dr. Babu Peter MD, DNB
Associate Professor, Barnard Institute of Radiology
Senior Consultant radiologist, Aarthi scans, Chennai