Table 4. Pre and post treatment VM features for ultrasound and MRI (16,18,26).

Imaging modality	Differential imaging characteristics categories	Pre-treatment features	Post-treatment features
Ultrasound	Architecture	Heterogeneous, tubular, torturous, acoustically shadowed phleboliths	Decreased size, involution of VM, absence of phleboliths
	Echogenicity	Hypo- or anechoic vascular space and formations	Hypo- or anechoic
	Flow	Low rate monophasic flow, though some can appear without any flow	Decreased flow
MRI	Architecture	Can appear septated with lobulated margins, infiltrates tissue planes and reveals full extent of infiltration at margins of lesion, surrounding edema possible, lower SI or signal voids represent dystrophic calcification or phleboliths, thrombi are hyperintense	Evaluation post 6 months shows decreased lesion size
	T1 imaging	Iso- or hypointense	Diminished signal intensity post 6 months
	T2 imaging	High signal intensity	Diminished signal intensity post 6 months
	Enhancement	Can be diffuse, hetero-, or homogenous	Early evaluation demonstrates heterogeneous high signal intensity in treated areas. Post 6 months enhancement is decreased
	Flow measurement	Low	In cases of extensive VM, gadolinium enhanced imaging is used to demonstrate residual perfusion of VM

VM, venous malformation; MRI, magnetic resonance imaging.