Flow characteristics of soft-tissue vascular anomalies evaluated by direct puncture scintigraphy

Soft-tissue vascular anomalies such as haemangioma and vascular malformation are treated by surgical resection, arterial embolization or sclerotherapy. Because the effect of sclerotherapy, i.e. the percutaneous injection of sclerosing agents, depends on intralesional haemodynamics, estimation of flow characteristics of soft-tissue vascular anomalies is essential when determining appropriate patient management. However, lesions are at present divided into only two groups: high flow and low flow. We have developed a new method, direct puncture scintigraphy, to evaluate in detail the haemodynamics of vascular anomalies under conditions simulating sclerotherapy. Twenty-six soft-tissue vascular anomalies in 21 patients were studied. After 30 MBq of technetium-99m Sn colloid was injected percutaneously into the intravascular space of the lesion, dynamic imaging was performed for 5 min. A time-activity curve for the lesion was generated, with the infiltrated activity on injection subtracted. A monoexponential curve was fitted to the declining phase of the time-activity curve, and mean vascular transit time (MTT) was obtained. The lesions were classified into high-flow and low-flow lesions based on radionuclide angiography with intravenous injection of 99mTc-labelled red blood cells, and estimates of MTT in the two groups were compared. The imaging procedures were carried out with no major complications, and broad intralesional diffusion of 99mTc-Sn colloid was achieved in most lesions. The high-flow lesions (six lesions) had a short MTT, ranging from 1.6 to 3.4 s, while the low-flow lesions (20 lesions) had a longer MTT, with no overlap between the groups. MTT showed a wide range in low-flow lesions: it was less than 30 s in six lesions and more than 10 min in five other lesions. Direct puncture scintigraphy provides a quantitative indicator of the flow characteristics of soft-tissue vascular anomalies, and may aid in determining treatment strategies for patients with vascular anomalies.