What is the role of MRI in the long-term monitoring of angiosarcoma (AS)?

Updated: Sep 04, 2018
  • Author: Maria Belén Carsi, MD, PhD, FRCS; Chief Editor: Edwin Choy, MD, PhD  more...
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Answer

The differential diagnosis for signal abnormality on a postoperative MRI includes the following:

  • Residual or recurrent neoplasm
  • Postsurgical/postradiation change
  • Scarring
  • Fluid collection

The residual or recurrent neoplasm usually is a discrete, ovoid, or rounded soft tissue mass. Nonspecific signal characteristics are present, with intermediate-to-low signal intensity in T1-weighted images and high signal on T2-weighted images. The lesion enhances with gadolinium. Comparison with prior postoperative examinations is essential.

Postsurgical/postradiation change usually appears as a regional distribution of signal abnormality, with a linear, trabeculated, or latticelike morphology. This has low-to-intermediate signal on T1-weighted images and high signal on T2-weighted images.

Scars show a linear morphology. Scars correspond with skin thickening and the loss of adjacent subcutaneous fat. A scar has low signal on both T1-weighted images and T2-weighted images, although they can present a linear high-signal intensity on T2-weighted images and a variable enhancement with gadolinium.

Fluid collection develops as an abscess, seroma, or hematoma. Seromas are the most common. They represent a signal intensity lower than muscle on T1-weighted images and high signal on T2-weighted images and can be differentiated from recurrence with gadolinium.

Hematomas usually appear in the subacute stage at the time of the first postoperative MRI. Because of the methemoglobin, hematomas show a characteristic high signal on T1-weighted images and T2-weighted images.

Abscesses present as low signal on T1-weighted images and high signal on T2-weighted images and may show some low-signal intensity depending on the presence of a fibrous capsule. Following gadolinium administration, they appear as a nonenhancing fluid collection with a thick, nodular, peripherally enhancing rim.


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