Korean J Radiol.  2009 Aug;10(4):323-332. 10.3348/kjr.2009.10.4.323.

Head and Neck Vascular Lesions: Characterization of the Flow Pattern by the Use of Three-Phase CT

• Ryu CW
• Kim JK
• Kim SJ
• Lee JH
• Kim JH
• Ha HI
• Suh DC

• KMID: 1777259
• DOI: http://doi.org/10.3348/kjr.2009.10.4.323

Abstract

OBJECTIVE
This study was designed to evaluate the usefulness of three-phase CT to characterize the hemodynamics of vascular lesions in the head and neck area.
MATERIALS AND METHODS
We analyzed vascular malformations of head and neck regions in 21 patients with the use of three-phase CT, including pre-contrast phase, vascular phase (scan delay: 20-35 seconds after intravenous contrast material injection) and equilibrium phase (scan delay: 3-5 minutes) imaging. The flow characteristic of each lesion was determined and categorized as either a high- or a low-flow lesion according to findings on selective arteriography and/or direct puncture venography. The CT number was acquired from two areas in a vascular lesion, sorted by the enhancement pattern: area 1, a highly enhanced area seen on the vascular phase; area 2, a delayedly enhanced area seen on the equilibrium phase. The CT numbers of each phase were compared between high- and low-flow lesions with use of the unpaired t-test. The flow patterns of high- and low-flow lesions were analyzed by assessment of time-density curves of three phase CT.
RESULTS
High-flow lesions were detected in nine patients and low-flow lesions were detected in 12 patients. On the vascular phase, the CT number of areas 1 and 2 of high-flow lesions was significantly higher than for low-flow lesions (p < 0.05). Contrary to early peaks seen in time-density curves of high-flow lesions, low-flow lesions showed a delayed peak.
CONCLUSION
Three-phase CT seems to be a valuable non-invasive method to differentiate a high-flow lesion from a low flow lesion of head and neck vascular lesions.

Keyword

Head and neck; Arteriovenous malformation; Three-phase CT

MeSH Terms

Adolescent
Adult
Angiography/methods
Arteriovenous Malformations/*radiography
Child
Female
Head/*blood supply
Humans
Male
Middle Aged
Neck/*blood supply
Tomography, X-Ray Computed/*methods

Figure

• 

  Fig. 1 Imaging findings for 32-year-old male with arteriovenous malformation in right cheek (patient 5) are presented. Pre-contrast (A), vascular (B) and equilibrium phase (C) CT images are shown. Focal areas of dense enhancement (arrow in B) are noted within lesion, but these areas were not differentiated from other areas of lesion as seen on equilibrium phase CT images (C). Focal, dense enhancement pattern corresponded to high-flow vascular lesion as seen on angiograms (D, E). Surgical resection after transarterial embolization revealed pathologically presence of arteriovenous malformation.

• 

  Fig. 2 Imaging findings for 18-year-old female with venous malformation in lower lip are presented. A. Pre-contrast CT image shows soft tissue mass in right lower lip. B. Focal area of enhancement is noted within lesion (arrows) on vascular phase image. C. Geographic enhancement is noted on equilibrium phase CT image. D. Direct-puncture venogram shows large, venous sac with venous drainage. Alcohol sclerotherapy could be safely performed for this venous malformation with slow filling-in and wash-out hemodynamics.

• 

  Fig. 3 Pattern of time-density curve for area 1 is shown. All of high-flow lesions (left) show dense (over 200 HU) enhancement on vascular phase CT images; this effect is markedly decreased on equilibrium phase. However, curve for low-flow lesion (right) shows various patterns. CT number of vascular phase is lower than for high-flow lesions.

• 

  Fig. 4 Pattern of time-density curve for area 2 is shown. Low-flow lesions (right) show marked elevation in equilibrium phase, thus indicating pooling of contrast medium in vascular lesions. Contrary to area 1, patterns of time-density curve in all patients are consistent for low-flow lesions, but vary for high-flow lesions.

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