Colour duplex ultrasound-guided sclerotherapy

Journal of Clinical Imaging 27 (2003) 171 – 179

Colour duplex ultrasound-guided sclerotherapy: A new approach to the management of patients with peripheral vascular malformations$ Balakrishnan Mahesha,*, Sanjay Thulkarb, George Josephc, Rakesh K. Khazanchia, Anurag Srivastavaa b

a Department of Surgery, All India Institute of Medical Sciences, New Delhi, India Department of Radiology, All India Institute of Medical Sciences, New Delhi, India c Department of Radiology, University Hospital of Wales, Cardiff, UK

Received 10 February 2002; accepted 25 March 2002

Abstract Introduction: Colour duplex ultrasound (CDU)-guided sclerotherapy is a valuable modality for treating peripheral vascular malformations (PVMs). Patients and Methods: Between April 1996 and October 1998, 75 patients (age 5 – 65 years) with PVMs were subjected to CDU. Sclerotherapy was subsequently performed on 40 patients, without sedation, using 3% sodium tetradecyl sulfate, with mean follow-up of 4 years. Results: CDU of the 33 high-flow lesions (HFLs) revealed direct arteriovenous (AV) communicating channels with very high forward diastolic flow in seven lesions (arteriovenous fistulas, AVFs), but not in the other 25 lesions (non-AVF). One was a mixed lesion picked up by CDU. Sixteen HFLs were subjected to sclerotherapy; 13 (81.25%) regressed. CDU of the 42 low-flow lesions (LFLs) helped categorize them into Type 1, where no supplying arteries could be seen (12 lesions), and Type 2, where supplying arteries were seen (30 lesions). Type 2 lesions could be further subcategorized based on the spectral trace of their supplying arteries: Type 2a, highresistance flow (25 lesions); and Type 2b, low-resistance flow with a small forward diastolic flow (5 lesions). Twenty-four LFLs were subjected to sclerotherapy; 20 (83.3%) regressed. Conclusion: CDU findings correlated well with the clinical appearances of PVMs, and helped to further subcategorize these lesions based on flow. Significant differences in the Doppler flowmetry parameters of the supplying arteries seen in the HFLs and LFLs have enabled us to suggest values for differentiating between them. CDU was also found to be valuable in the follow-up of these lesions. D 2003 Elsevier Science Inc. All rights reserved. Keywords: Peripheral vascular malformation; Sclerotherapy; Arteriovenous fistulas; Colour duplex ultrasound; High-flow lesions; Low-flow lesions

1. Introduction Peripheral vascular malformations (PVMs) have been defined and classified in a variety of ways in the past, based on their gross appearances and clinical characteristics [1– 3]. They are different from hemangiomas, in that they are present at birth and show an increase in size throughout life [3]. Jackson et al. [4] classified them clinically as (a) low-flow lesions (LFLs), previously called venous malfor$ Presented at the United Kingdom Radiological Congress 2001, Wembley Park, London, UK, May 2001. * Corresponding author. C/o Prof. Dreyfus’ Office, Harefield Hospital, Hill End Road, Harefield, Middlesex UB9 6JH, UK. E-mail address: [email protected] (B. Mahesh).

mations (VMs), and (b) high-flow lesions (HFLs), previously called arteriovenous malformations (AVMs). This classification was subsequently confirmed by angiography, based on flow through the lesion and the rate of shunting between the arterial and venous components [2,5,6]. Angiography has traditionally been the gold standard for the precise evaluation of PVMs and their characterization into HFL and LFL [2,5,6]. However, it is an invasive procedure and associated with significant complication rate [7,8]. Furthermore, the information that it provides is only morphological and, therefore, the hemodynamic impact and the flow characterization of these lesions can only be inferred [7]. Newer investigations like colour duplex ultrasound (CDU) have been satisfactorily used by various workers for initial evaluation and follow-up of PVMs [9 – 12].

0899-7071/03/$ – see front matter D 2003 Elsevier Science Inc. All rights reserved. doi:10.1016/S0899-7071(02)00503-X

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Studies comparing CDU with angiography in PVMs have been performed in the past [10 –12], but patient numbers have been small. On the other hand, significant advances have been made in the use of CDU in peripheral vascular disease, wherein several investigators found that CDU had the potential to replace standard angiography in carefully selected patients for diagnosis as well as for guidance in therapeutic vascular interventions [7,8,13,14]. CDU has advantage over angiography in that it provides additional information on the hemodynamics of the vascular lesions and, due to its noninvasive and inexpensive nature, can be repeated as often as deemed necessary [13 –15]. In the treatment of these lesions, aggressive surgery may lead to significant loss of motor function, nerve damage and massive bleeding [16]. Sclerotherapy is an established alternative mode of treatment, which has been used to treat carefully selected lesions [10,11,17,18], but CDU was not used in these studies. CDU-guided sclerotherapy has been used to treat LFL [16,19]. Not much work has been done on the management of patients with HFL using CDU and sclerotherapy [15]. The main objectives of this study were to assess the use of CDU in aiding the clinical classification of PVMs into highand low-flow types, based on flowmetry parameters, and to guide sclerotherapy in these patients on an outpatient basis. CDU was found valuable in treatment planning and in prediction of the outcome of sclerotherapy. It also helped to decide the number of sessions of sclerotherapy required and the volume of the sclerosant to be used. Prior knowledge of high-flow pattern helped to determine the need for use of a tourniquet during and after sclerotherapy. This enhanced the chances of success by allowing the sclerosant to remain in the lesion for a longer period of time [3]. Angiography was not used for preliminary investigation as this study was designed to be minimally invasive. Furthermore, we also wished to avoid the complications of angiography [7,8]. Only lesions that had not subsided with multiple sittings of sclerotherapy were referred for angiography and surgical treatment.

2. Patients and methods 2.1. Patients This prospective study consisted of 75 patients (40 males, 35 females) with PVMs who attended the general surgical and plastic surgical outpatients department of our hospital from April 1996 to October 1998. Their ages ranged from 5 to 65 years. All patients were carefully examined by members of the vascular malformation team that included surgeons with a special interest in these lesions, plastic surgeons and radiologists. These were classified into HFL and LFL based on the criteria proposed by Jackson et al. [4]. Lesions that were warm, compressible, pulsatile, filled up quickly on release of compression and had a bruit were designated HFLs. The LFLs

were neither pulsatile nor had a bruit and filled up slowly on release of compression. The ethical clearance was obtained from the ethical committee of our hospital and informed consents were obtained from the patients. CDU was preformed using a Sonoline Versa Ultrasound machine (Siemens, Germany) and linear array transducers of 7.5 MHz were used, this being the highest available frequency in this machine at the time of the study. Lower frequency transducers were not used so as to avoid decreased spatial resolution and deterioration of the B-mode image [14]. The transducer power output was set below 100 mW/cm2 and 50 Hz wall filter was used. A custom-made stand-off pad was used for very superficial lesions. The lesions were initially scanned in B-mode in both transverse and longitudinal planes. The presence of dilated vascular channels, intervening soft tissue component, compressibility, thrombosis and calcification was noted. During CDU evaluation, the velocity scale and colour sensitivity were adjusted and individualized to permit optimal visualization of flow. Detection of low-velocity arterial and venous flow was made possible by keeping the colour scale low enough to optimally demonstrate colour and high enough to avoid aliasing. 2.2. CDU image analysis High-velocity, pulsatile and turbulent flow pattern was consistent with arterial channels and continuous slow flow was consistent with venous channels. Anechoic channels with a very sluggish flow demonstrated only on compression and release of pressure also suggested venous channels. Direct arteriovenous fistulas (AVFs) showed prominent systolic pulsations and a very high diastolic flow with aliasing and colour artifacts (colour bruit) in adjacent soft tissues. Spectral tracings were obtained from various channels to document arterial or venous flow. Arterial evaluation was considered adequate if minimum of two consecutive equivalent waveforms were obtained from one channel. From an intralesional artery, spectral analysis was performed and Doppler flowmetry parameters, i.e., pulsatility index (PI), resistive index (RI) and systolic/diastolic (S/D) ratio, were obtained [20,21]. Finally, the surrounding area was scanned in an attempt to locate the artery leading to the lesion whenever possible. This was traced proximally to a major vessel and distally into the lesion. If it was established that this could be the supplying artery, then its waveform and Doppler flowmetry parameters were noted. Doppler flowmetry parameters were expressed in indices and ratios as opposed to absolute velocities to make them independent of the angle of placement of the transducer. 2.3. Statistical analysis Data analysis was conducted using the Wilcoxon Rank Sum Test for nonparametric distributions. Differences were considered significant at P < .05 [16].

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2.4. Sclerotherapy Deep-seated inaccessible vascular malformations, those near the eye, in the tongue and in the digits, were excluded from sclerotherapy to avoid serious complications. Infection was another contraindication to sclerotherapy. These patients were treated with antibiotics to allow the infection to subside. Sclerotherapy was performed using 3% sodium tetradecyl sulfate (STS) on an outpatient basis, without general anaesthetic, using full aseptic precautions. A 24-gauge needle was used and the lesion was entered by a ‘‘Z-track’’ technique, at a point a few millimeters away from the site of the skin puncture, by stretching the skin. Based on our experience, this technique was found to prevent persistent ooze from the site of puncture. The dose of STS to be injected was decided by our team, based on past experience, as 0.25 ml/cm2 of the surface area of the lesion, the maximum being 8 ml in each lesion. The sclerosant was injected well within the main mass of the lesion after drawing up blood to confirm that the tip of the needle was in the lumen of the lesion. The procedure was stopped if the patient complained of undue pain or excessive discomfort during the procedure. For HFL in the limbs, a tourniquet was applied proximal to the lesion and inflated to above systolic arterial pressures prior to sclerotherapy. This was retained for 15– 20 min after the procedure to prevent immediate wash-off of the sclerosant. It was removed earlier if the patient complained of excessive discomfort. For lesions on the scalp, the back or the trunk, an assistant compressed the perimeter of the lesion to achieve the same purpose. Cotton balls with elastic tape were generally used at puncture sites for pressure. A crepe bandage or a custom-made compression garment was applied over the lesion prior to removal of the tourniquet

Fig. 2. Colour Doppler appearance of a mixed lesion showing channels with arterial and venous flow together with the spectral trace from a venous channel.

or the compression around the lesion. This was maintained for a week to prevent post-injection bleeding and oedema. Patients were warned about the possible increase in the size of the lesion due to oedema in the early days to allay any anxiety. They were then discharged on anti-inflammatory agents and analgesics for a period of 2 weeks. 2.5. Postsclerotherapy evaluation methods At each monthly follow-up visit, the same team examined the lesions. CDU was performed and any residual channels, if present, were injected under CDU guidance. If completely regressed, the patients were followed with three monthly clinical and CDU examinations for a period of 4 years. The vascular malformation team decided on six sittings of injection as being an adequate trial of sclerotherapy. Lesions that did not regress were subsequently referred for angiography and surgical management.

3. Results

Fig. 1. Colour Doppler appearance of a HFL showing gross turbulence in its vascular channels.

There were 33 patients with clinically diagnosed HFLs, characterized by warmth, pulsatility, compressibility and bruit. Mean size was 7.182 cm (range 2 – 25 cm; S.D. 4.962). On CDU, all these demonstrated high vascularity. All were found to be nonhomogeneous in echotexture, consisting of a mixture of channels of various sizes; 29 (87.9%) were compressible on initial examination and 4 (12.1%) showed a few thrombosed channels, which were not compressible. None had any calcification. In all these lesions, CDU demonstrated pulsatile and turbulent flow in the vascular spaces (Fig. 1). The spectral trace obtained from these spaces was of the high-flow type, with a continuous forward flow in diastole.

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Fig. 3. Colour Doppler appearance of a HFL together with the spectral trace from its artery showing a high-flow, low-resistance system.

Based on CDU findings they were classified into three groups, which were not obvious on clinical examination of the HFL and probably had a bearing on the results: 1. AVF, showing obvious arteriovenous (AV) communicating channels, demonstrating a very high forward diastolic flow on spectral trace, 7 lesions; 2. purely arterial lesions with arterial channels only, and no obvious AV communicating channels as in the AVF (non-AVF), 25 lesions; 3. one mixed lesion, with both arterial and venous channels (Fig. 2); the venous channels occupied a different part of the lesion and there was no obvious communication between the two parts. Supplying artery and intralesional artery were demonstrated in all the HFLs on initial CDU. Their spectral trace was of the high-flow, low-resistance type achieving a continuous forward flow in diastole (Fig. 3). Their pretreatment parameters are shown in Table 1. In the seven AVFs, mean PI, RI and S/D ratios were 0.54, 0.40 and 1.81, with S.D. of 0.29, 0.19 and 0.57, respectively, in their intralesional arteries, and 0.70, 0.52 and 1.96 with S.D. of 0.12, 0.07 and 0.31, respectively, in their supplying

Fig. 4. Colour Doppler appearance of a venous channel in a low flow lesion.

arteries. In the 25 non-AVFs, mean PI, RI and S/D ratios were 0.84, 0.55 and 2.65, with S.D. of 0.33, 0.16 and 1.28, respectively, in their intralesional arteries, and 0.92, 0.60 and 3.13, with S.D. of 0.32, 0.16 and 1.90, respectively, in their supplying arteries. The differences in these parameters between the two types of AVMs were significant ( P < .001). However, no values can be suggested at present for distinguishing between the AVFs and the non-AVFs due to small numbers in each group. Clearly, CDU findings of AV communicating channels showing very high forward diastolic flow on spectral trace would be a prerequisite to categorization of the lesion as an AVF. There were 42 patients with clinical LFL characterized by the absence of bruit, thrill or pulsatility. Mean size was 9.27 cm (range 1.5 – 25 cm; S.D. 5.26). On CDU, all the lesions were compressible and nonhomogeneous in echotexture, showing dilated venous channels with diameters ranging from a few millimeters to 2 cm (Fig. 4). Spectral trace obtained from these channels was of the nonpulsatile, low-flow and venous type. Supplying arteries were demonstrated in 30 lesions (71.4%). Their initial flowmetry parameters are shown in Table 2. On the basis of spectral trace on CDU, two types of LFL were noted, which were again not found on clinical examination and probably had a bearing on the results: (1) lesions with very low flow in which supplying artery was not seen, 12 (28.6%);

Table 1 Pretreatment parameters of the 33 HFLs Parameters

Mean

Median

95% CI

Intralesional artery PI RI S/D ratio

0.78 0.52 2.47

0.78 0.52 2.1

0.66 – 0.9 0.46 – 0.59 2.04 – 2.89

Supplying artery PI RI S/D ratio

0.87 0.59 2.89

0.83 0.57 2.8

0.77 – 0.99 0.54 – 0.64 2.29 – 3.53

PI, pulsatility index; RI, resistivity index; S/D ratio, systolic/diastolic ratio.

Table 2 Pretreatment parameters of CDU in the 30 LFLs where supplying arteries were demonstrated Parameters

Mean

Median

95% CI

Supplying artery PI RI S/D ratio

1.42 0.71 4.9

1.25 0.725 4.55

1.11 – 1.59 0.68 – 0.78 3.94 – 5.77

PI, pulsatility index; RI, resistivity index; S/D ratio, systolic/diastolic ratio.

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Table 3 Response rates in the three types of HFLs After three sittings

After six sittings

Overall response

Lesion characteristics

Initial number

Scl

Ra

PR

NR

Ra

PR

NR

Ra

PR

NR

Non-AVF AVF Mixed

25 7 1

12 3 1

1 2 0

8 1 1

3 0 0

8 1 1

0 0 0

3 0 0

9 (75%) 3 (100%) 1 (100%)

0 0 0

3 (25%) 0 0

AVF, HFLs with AVF; non-AVF, HFLs without AVF; NR, nonregressed lesions; PR, partially regressed lesions; R, regressed lesions; Scl, lesions subjected to sclerotherapy. a All these regressed lesions were not given any more injections.

of these. The remaining 17 HFLs were not treated due to the exclusion criteria. The 20 LFLs selected for sclerotherapy had a mean pretreatment size of 8.72 cm (range 1.5 – 25 cm; S.D. 5.37). On CDU, supplying arteries were seen in 14 lesions. Their mean pretreatment PI, RI and S/D ratios were 1.21, 0.73 and 4.73 with S.D. of 0.3, 0.11 and 2.45, respectively. After three sittings of sclerotherapy, seven had completely regressed and, in these, the supplying artery could not be seen on CDU. Thirteen had partially regressed with >50% reduction in size. Their mean size then was 4 cm (range 6– 20 cm; S.D. 5.01), which was a significant reduction ( P < .001). These showed some noncompressible, thrombosed or partially thrombosed channels, a decrease in the size and number of venous channels and an increase in intervening soft tissue on CDU. None was compressible or homogeneous in echotexture. Supplying arteries were seen in all of these. Their mean PI, RI and S/D ratios were 1.57, 0.75 and 4.98 with S.D. of 0.66, 0.08 and 2.17, respectively, which were not significantly different from their pretreatment values. Four LFLs had not regressed with sclerotherapy. None was homogeneous in echotexture or compressible. The mean size was 10.88 cm (range 6 – 15.5 cm; S.D. 4.59), which was not significantly different from their mean pretreatment size of 11.88 cm (range 7 – 16 cm; S.D. 4.55). The supplying artery was seen in three of these. The remaining 18 LFLs were not injected due to the exclusion criteria.

(2) lesions in which the supplying artery was demonstrated, 30 (71.4%), with: (a) no diastolic flow or a flow reversal early in diastole, 25 (83.3%); (b) forward diastolic flow, indicating a larger diastolic flow, 5 (16.7%). 3.1. After three sittings of sclerotherapy The 13 HFLs selected for sclerotherapy had a mean pretreatment size of 7.58 cm (range 2 – 20 cm; S.D. 4.32). They demonstrated mean pretreatment PI, RI and S/D ratios of 0.84, 0.54 and 2.82 with S.D. of 0.43, 0.22 and 1.47, respectively, in their intralesional arteries and 0.97, 0.62 and 3.66 with S.D. of 0.39, 0.20 and 2.51, respectively, in their supplying arteries. After three sittings of sclerotherapy, three (18.8%) lesions regressed completely: two AVFs and one non-AVF. Ten lesions (81.2%) had regressed partially ( > 50% reduction in size): one AVF, one mixed lesion and eight non-AVFs. Their mean size was 3.92 cm (range 0 –10 cm; S.D. 3.22), which was a significant reduction ( P < .05). Bruit, thrill and pulsatility were present only in two. Intralesional and supplying arteries were demonstrated in eight lesions. The mean PI, RI and S/D ratios were 1.02, 0.56 and 2.9 with S.D. of 0.60, 0.26 and 1.52, respectively, in the supplying arteries and 0.64, 0.43 and 2.26 with S.D. of 0.50, 0.30 and 2.19, respectively, in the intralesional arteries. None was homogenous or compressible. Three lesions did not regress with three sittings of sclerotherapy, retaining their pretreatment sizes of 3, 4.5 and 7 cm. All were nonAVFs. None was homogeneous in echotexture or compressible. Bruit, thrill and pulsatility were present in all of these. Intralesional and supplying arteries were demonstrated in all

3.2. After six sittings of sclerotherapy The 13 HFLs remaining were subjected to further sclerotherapy. Ten lesions completely regressed: one AVF, one

Table 4 Response rates in the three types of LFL After three sittings

After six sittings

Overall response

Spectral trace analysis of supplying artery

Initial number

Scl

Ra

PR

NR

Ra

PR

NR

Ra

PR

NR

No vessel seen No or reverse diastolic flow Forward diastolic flow

12 23 7

7 12 5

2 3 2

5 7 1

0 2 2

1 0 0

4 7 1

0 2 2

3 (43%) 3 (25%) 2 (40%)

4 (57%) 7 (58%) 1 (20%)

0 2 (17%) 2 (40%)

NR, nonregressed; PR, partially regressed; R, regressed; Scl, sclerosed. a All these regressed lesions were not given any more injections.

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Table 5 Complications of sclerotherapy Complications

HFL

LFL

Swelling/oedema Pain Temporary numbness/paresthesias Bleeding Superficial epithelial blackening/sloughing Gangrene of one or more toes

16 12 3 2 2 0

24 20 5 1 0 1

(100) (75) (19) (13) (13) (0)

(100) (83) (21) (4) (0) (4)

Figures in parentheses include percentage of the total number of treated HFL or LFL. HFL, high-flow lesion; LFL, low-flow lesion.

mixed lesion and eight non-AVFs. Only three lesions remained and these were the ones that had not regressed initially. None was homogeneous in echotexture or compressible. Two lesions exhibited bruit, thrill and pulsation. Spectral trace demonstrated a high-flow pattern. Other features noted on CDU included a decrease in the number and size of vascular channels, the presence of partially or completely thrombosed channels and an increase in soft tissue density as compared to the previous Doppler studies. They were no longer totally compressible and showed areas of thrombosis. Table 3 shows the response of the various types of HFLs to sclerotherapy. Of the 13 LFLs that had partially regressed initially, one had regressed fully. In the remaining 12 lesions, the mean size was 4.67 cm (range 2– 15 cm; S.D. 5.39), which was a significant reduction ( P < .001). The supplying artery could be seen in only one lesion with PI, RI and S/D ratio of 1.69, 0.74 and 4.5, respectively. All lesions demonstrated a decrease in the number of venous channels and sinusoids, an increase in thrombosed and partially thrombosed noncompressible channels and an increase in soft tissue density. The four lesions that had not regressed initially had not regressed at all. However, they did exhibit a decrease in the number of venous channels and sinusoids, an increase in the number of thrombosed and partially thrombosed noncompressible channels and an increase in the intervening soft tissue. Table 4 shows the overall response of the various types of LFLs to six sittings of sclerotherapy. 3.3. Complications of sclerotherapy Postinjection swelling and oedema were observed in all lesions. The other complications are summarized in Table 5.

4. Discussion CDU has been used satisfactorily by a few groups in the management of vascular malformations. Bingham [9] used the Doppler apparatus to determine the number and activity of AVF and concluded that sclerotherapy could be used in conjunction with Doppler follow-up. Oates et al. [11] examined selected AVMs by CDU and found that the

feeding vessels showed a low peripheral resistance, high systolic velocities and persistently high flow throughout diastole. Other workers subsequently used CDU for evaluation of the extent of AVMs and to demonstrate AV shunt within these lesions [5,10]. Yoshida et al. [12] observed that HFL had arterialised or pulsatile flow pattern and that the supplying artery demonstrated an increase in PI after embolisation. His group concluded that for AVMs, CDU flow imaging could study the hemodynamic nature and was preferable to angiography in evaluating the response to treatment. Paltiel et al. [15] extensively studied several PVMs that were difficult to diagnose by clinical methods and concluded that CDU was a very useful screening procedure and was valuable in directing subsequent management. Furthermore, several workers felt that diagnostic angiograms were unnecessary in LFL [1,3]. Normally in the peripheral vascular system, the arteries demonstrate pulsatile flow with high peak systolic velocities. There is little or no detectable flow in diastole due to high peripheral impedance offered by arterioles and precapillary sphincters. There may be a small phase of flow reversal at the end of systole due to elastic recoil of the arteries. HFLs have a low impedance circuit because of direct run-off from arterial to the venous circulation through thin-walled, low-resistance channels or sinusoids, which accounts for the high continuous forward flow in diastole resulting in low PI, RI and S/D ratio. In our study of 33 HFLs, gray scale images showed dilated, pulsatile channels. Colour Doppler imaging demonstrated a mixture of colours (Fig. 1) and a high-pitched audio signal, suggestive of a pulsatile turbulent flow. Spectral trace of the supplying and intralesional arteries showed a low-resistance flow pattern with continuous, forward diastolic flow (Fig. 3). Obvious AV communicating channels demonstrating a very high forward diastolic flow on spectral trace could be seen in the AVFs, wherein the supplying and intralesional arteries demonstrated much lower mean PI, RI and S/D ratios as compared to those of the non-AVFs, suggestive of very rapid run-off from the arterial to the venous system through fistulous channels. The variability in the parameters of the AVF could be easily explained by the difference in the number and size of the fistulas and the constituent vessels. In the LFL, CDU showed dilated venous channels exhibiting a very sluggish flow (Fig. 4) or flow only on compression and release of pressure, but not otherwise. CDU did not show any flow, unless the channels were compressed and released. Absence of flow on CDU does not mean a no-flow state as flow with a velocity of less than the critical value will not be detected by CDU. Mixed lesions (Fig. 2) were also exclusively picked up by CDU. The differences between the HFL and LFL in the Doppler flowmetry parameters of their supplying arteries (shown in Tables 1 and 2) were found to be significant ( P < .001). They indicated a much larger peripheral shunting of blood from the arterial to the venous system in the HFL

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as compared to the LFL. Based on 95% confidence interval (CI) values, we suggest that values of PI, RI and S/D ratio of 1.05, 0.66 and 3.73 in the supplying arteries, respectively, could be used to differentiate between the HFL and LFL. The HFL would have values that were lower, and the LFL would have values that were higher than those suggested above. This information would have to be integrated with that obtained from the gray scale and the colour Doppler imaging to be able to confidently distinguish between HFL and LFL on CDU. CDU thus provides a noninvasive method of evaluating these lesions and confirming the clinical findings, which would be useful in modifying the technique of sclerotherapy based on the vascularity of these lesions. HFL would require the use of a proximal tourniquet or compression around the perimeter of the lesion to decrease the flow and to prevent the sclerosant from being washed off. In the treatment of PVM, aggressive surgeries often result in significant loss of motor function, nerve damage and bleeding and may even result in recurrence. In the past, sclerotherapy has been used successfully [1,17,18] and is rapidly becoming accepted as the best treatment for PVMs [16]. Duplex-guided sclerotherapy has been found to be much safer as accidental intraarterial injection of sclerosant, with its disastrous consequences, can be avoided. This method is also useful for deep-seated intramuscular lesions [16]. Various sclerosing agents have been used in the past. De Lorimier [1] preferred sodium morrhuate in most of his patients. Svendsen et al. [22] and Yakes et al. [23] used alcohol and obtained good results. Later, Siniluoto et al. [24] also used STS and obtained satisfactory results. Absolute alcohol is the most destructive sclerosant and is considered to give the lowest recurrence rate [3,16]. However, ulceration and neuropathy are possible complications. STS, though less potent, is safer [16]. In addition, it has been shown to produce long-term arterial thrombosis in the larger vessels and marked inflammation and eventual fibrosis in the smaller vessels [3]. Sclerotherapy, as a technique, is more effective in the LFL, where the sclerosant remains in the lesion for a longer time. O’Donovan et al. [3] have reported a beneficial effect with a proximal tourniquet or compression around the perimeter of the lesion in lesions with prominent venous flow. In HFL, a similar low-flow state can be achieved temporarily by using a proximal tourniquet for lesions in the limbs or compression around the perimeter for lesions in other sites, thus achieving stasis and preventing the sclerosant from being washed off. We feel that adoption of this technique to treat HFL increases the chances of success, though we were not able to test this due to the small number of patients injected in this group. Percutaneous injection is the preferred approach presently with a high reported success rate [1,3,16,24]. This is simpler and quicker and avoids the potential complications of subselective catheterisation required for intraarterial sclerosant injection [3].

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Sclerotherapy was beneficial in 20 (83.3%) of 24 patients with LFL. This compares well with the success rates of 86% reported by O’Donovan et al. [3], 82% reported by Yamaki et al. [16] and by other workers [1,17,18]. This success rate was not substantially different from that obtained in the sclerotherapy of HFL where 13 (81.25%) of 16 lesions had regressed. The success rate of sclerotherapy with the three AVFs was 100%. HFLs were injected after temporary application of tourniquet proximally or perimeter compression to achieve stasis in the lesion. Of the LFLs, all the Type 1 lesions had either completely or partially regressed. There were 12 Type 2a lesions, of which 10 (83.3%) had either completely or partially regressed and 2 (16.7%) had not regressed. There were five Type 2b lesions and these demonstrated an overall poorer response. Of these, only three (60%) had either completely or partially regressed and two (40%) had not. These findings lead to the obvious conclusion that subcategorization of the LFL based on the spectral trace of the intralesional and the supplying arteries would be useful in terms of predicting the outcome of these lesions after sclerotherapy and in explaining this to the patients. However, it would be difficult to apply tests of significance to the small numbers in each subcategory. We found that using the Doppler flowmetry parameters alone did not provide a clear indication of the success of sclerotherapy during follow-up. In the HFL group, after three sittings of sclerotherapy, 3 (18.8%) lesions completely regressed and 10 lesions (81.2%) had partially regressed. However, the intralesional artery and the supplying artery had not shown any significant change in the PI, RI and S/D ratio in these lesions, but could not be demonstrated in five lesions, including the three lesions that had regressed completely. In the LFL group, after three sittings of sclerotherapy, 7 had completely regressed and 13 had partially regressed. CDU showed these to have some noncompressible, thrombosed or partially thrombosed channels, a decrease in the size and number of venous channels and an increase in intervening soft tissue. None was compressible or homogeneous. Supplying arteries were, however, seen in the partially regressed lesions, with no significant difference in their mean PI, RI and S/D ratios before and after treatment. After six sittings of sclerotherapy, 1 more lesion had fully regressed and 12 had partially regressed. All these lesions demonstrated a decrease in the number of venous channels and sinusoids, an increase in thrombosed and partially thrombosed noncompressible channels and an increase in soft tissue density. Thus, we feel that Doppler flowmetry criteria alone cannot be completely relied upon to document success following sclerotherapy. Gray scale ultrasound appearances including homogeneity, compressibility, decrease in the number and size of vascular channels and an increase in the number of thrombosed channels and intervening fibrous soft tissue may be as useful in the follow-up as the Doppler flowmetry criteria. Furthermore, nonvisualisation of the supplying and/or the intralesional arteries on

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follow-up examination of those lesions where they were initially demonstrable would have an important bearing on documenting regression. Common complications of sclerotherapy include skin necrosis, ulceration and peripheral nerve damage [3,16]. We, however, found that the most common complications were oedema and swelling and these were more often seen in the lesions on the face where the subcutaneous tissue is lax, as opposed to the scalp where the dense connective tissue does not permit as much swelling. Pain was another important complication, which responded reasonably well to the nonsteroidal analgesics. Minor bleeding responded readily to pressure and compression bandage. Numbness and paresthesias were transiently noted in eight (20%) patients, which subsided following decrease in the swelling following sclerotherapy. Superficial blackening of the skin following sclerotherapy was seen in two patients with HFL. One patient had superficial blackening of the scalp in the region of the temporoparietal area, associated with a patchy alopecia and desquamation, which improved on conservative treatment. The other patient had superficial blackening of the upper half of the pinna following injection of a lesion on the pinna, which improved on conservative treatment. Both lesions completely regressed subsequently. One patient had ischemic changes of the distal half of her right foot following sclerotherapy. The site of injection was far removed from any artery, but the presence of collaterals could have accounted for this complication. She was judged to be unsuitable for any vascular intervention by the vascular surgical team. She was managed conservatively with high-dose heparin and epidural analgesia. She subsequently underwent conservative amputations of parts of two toes following development of a clear line of demarcation.

5. Conclusions We conclude that CDU is a valuable modality in the management of patients with PVMs. Doppler flowmetry parameters appear to be useful in the initial categorization of patients with PVMs and appear to contribute significantly to the clinical findings. CDU obviates the need for angiography for the diagnosis and the initial nonsurgical treatment of these lesions. It is noninvasive, relatively inexpensive and can be repeated as often as necessary. Furthermore, it may help predict the response of the lesion to sclerotherapy. Gray scale ultrasound appearances correlate well with the clinical outcome and can be used to monitor regression of the lesion. Doppler flowmetry parameters cannot exclusively be used for follow-up owing to disappearance of the vessels in the fully regressed lesions, and therefore need to be integrated with the gray scale ultrasound appearances. Sclerotherapy with STS is a good initial modality of treatment for HFL and LFL not located in the digits, eye or

tongue. However, the larger lesions may respond less well to this modality. After confirming their nature on CDU, temporarily decreasing the blood flow in the HFL by the use of a proximal tourniquet for those in the limbs or a rubber ring around the perimeter of the HFL at sites other than the limbs, sufficient to obliterate the arterial pulsation, makes it possible to treat them with sclerotherapy by minimizing the immediate washout of the sclerosant.

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