2017 Sec 1 Green Book

Fig 12. Axial fat-suppressed T1-weighted (A), fat-suppressed T2-weighted (B), and contrast enhanced fat-suppressed T1-weighted (C) MR images of a child with a lymphatic malformation. The axial images show a large, well-defined macrocystic cystic structure in the left posterior cervical triangle. The cyst demonstrates fluid-fluid levels and enhancement of the peripheral cyst wall and septa (C). Multiphasic dynamic contrast–enhanced MRA images (D-F) reveal no arterial or venous enhancement of the lesion. Note the displacement of the external jugular vein due to mass effect (E, F).

Fig 13. Axial T1-weighted (A), fat-suppressed T2-weighted (B), and contrast enhanced fat-suppressed T1-weighted (C) MR images of a child with a venous malformation. The T2-weighted images (B) show a hyperintense mass in the right masticator space with trans-spatial infiltrative extension. Hypointense phleboliths are present in the mass. Multiphasic dynamic contrast enhanced MRA images (D-F) demonstrate progressive enhancement during the early (E) and late (F) venous phase (arrows).

can appear in the lesion, and although this finding is more typ- ical for lymphatic malformations, all slow-flow vascular mal- formations have the potential to show fluid-fluid levels. Phle- boliths are best depicted on susceptibility weighted sequences. Intralesional fluid-fluid levels are rarely present and this may be used as a differentiating feature to distinguish venous malformations from lymphatic malformations. Involvement of

the adjacent osseous structures includes osteal defects, deminer- alization, hypoplasia, and cortical thickening. Multiphasic time- resolved dynamic cMRA imaging demonstrates a slow flow pat- tern revealing typical slow gradual venous enhancement with variable degree of contrast enhancement on delayed images (Fig 13). 7,8,35,36 Venous malformations are occasionally seen in blue rubber bleb nevus, Proteus and Maffucci syndromes. 37

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