How I do it. Arteriovenous malformation management

Pediatric vascular malformations: pathophysiology, diagnosis, and the role of interventional radiology

The Mulliken and Glowacki classification (1982) differentiated vascular anomalies into two groups based on their endothelial characteristics: hemangiomas and vascular malformations. Vascular anomalies are localized defects of the vasculature that affect a limited number of vessels in a restricted area of the body. These defects are secondary to errors in vascular morphogenesis. Depending on the type of vessel involved, the vascular malformation group was subdivided into high-flow (such as arteriovenous malformation and arteriovenous fistula) and low-flow lesions (such as venous and lymphatic malformations). Depending on the type of lesion, the location and degree of involvement and the clinical effect, different types of treatment would be required. For the purpose of this review, we concentrate solely on vascular malformations: the clinical features, genetics, diagnosis, and current treatment options.

Ethanol threshold doses for systemic complications during sclerotherapy of superficial venous malformations: a retrospective study

INTRODUCTION

Ethanol has been used for many years for superficial venous malformations (VM) sclerotherapy. Although ethanol is well-tolerated in most of the cases, systemic side effects have been reported in some patients, including cardiac collapse and death. Systemic toxic side effects have been suspected to be proportional to the ratio of ethanol dose divided by the patient's body weight (dose/weight ratio in millilitre per kilogram). No extensive study has yet been conducted to determine the toxic threshold, and no consensus exists on this point.

METHODS

We retrospectively studied the systemic effects of ethanol sclerotherapy in a consecutive series of 71 patients with VM.

RESULTS

Seventy-one consecutive patients with VMs were treated by ethanol sclerotherapy and 162 procedures were performed. The only factor significantly associated with a systemic adverse event was the ethanol dose/weight ratio per intervention. The ethanol dose/weight ratio superior to 0.24 ml/kg was predictive of systemic toxic effects, suggesting a limit dose for ethanol sclerotherapy of VM. Systematic complications were not related to repetitive sclerotherapy sessions.

CONCLUSION

Based on our findings, a maximal ethanol dose/weight ratio of 0.2 ml/kg could be considered as acceptable in VM treatment indications.

Exaggerated increase in cardiac output during exercise in patients with peripheral high-flow arteriovenous malformations

PURPOSE

To test the hypothesis that cardiac output (Q) in patients with arteriovenous malformations (AVMs) is normal at rest and increases disproportionately during exercise.

MATERIALS AND METHODS

Q was measured in eight patients with large peripheral AVMs and in nine healthy subjects using a noninvasive carbon dioxide (CO₂)-based differential Fick method. Subjects were tested while seated at rest and during mild exercise (repeated leg straightening while sitting). Oxygen consumption (VO₂) was monitored as an index of the degree of exercise.

RESULTS

Average resting Q was similar between AVM patients and healthy subjects (7.40 L/min ± 3.29 vs 6.13 L/min ± 0.94, respectively, P = .29). During exercise, AVM patients showed a smaller increment in VO₂ (0.50 L/min ± 0.11 vs 0.78 L/min ± 0.26, P = .012) but with more apparent effort and shortness of breath compared with healthy subjects. The change in Q per unit change in VO₂ (ΔQ/ΔVO₂) was greater in AVM patients than in healthy subjects (16.00 L/min ± 6.50 vs 9.79 L/min ± 5.33, P < .045).

CONCLUSIONS

Exercise intolerance in AVM patients may be due to an imbalance in ΔQ/ΔVO₂ resulting from increased shunting through the AVM. Exercise provocation may increase the sensitivity of Q in the clinical evaluation of AVM patients.

Cardiovascular effects and predictability of cardiovascular collapse after repeated intravenous bolus injections of absolute ethanol in anesthetized pigs

PURPOSE

To evaluate the effects of repeated intravenous bolus injections of absolute ethanol on cardiopulmonary hemodynamic changes and to investigate the predictability of ethanol-induced cardiovascular collapse in anesthetized pigs.

MATERIALS AND METHODS

Twenty pigs aged 3-6 months and weighing 28-38 kg were enrolled in the study. Absolute ethanol (0.1 mL/kg of body weight) was repeatedly injected through the inferior vena cava central to the renal vein at 10-minute intervals up to a total volume of 1.0 mL/kg. The subjects were divided into a cardiovascular collapse group and a no-collapse group according to the development or absence of cardiac collapse.

RESULTS

Among the 20 pigs, 12 died before the final injection. Hemodynamic parameters measured immediately before the injection of absolute ethanol did not differ between the cardiovascular collapse group and the no-collapse group except that among animals with cardiovascular collapse, the injection immediately before the one causing cardiovascular collapse resulted in significant increases in the following hemodynamic parameters: mean pulmonary arterial pressure (P < .01), pulmonary vascular resistance (P = .04), and right ventricular end-diastolic volume (P = .02). No such increases were observed in the no-collapse group.

CONCLUSIONS

Hemodynamic profiles in pigs obtained immediately before intravenous injection of absolute ethanol did not predict the subsequent occurrence of cardiovascular collapse except after the injection immediately preceding the one resulting in cardiovascular collapse. In this animal model, significant increases in select hemodynamic parameters occurred after the injection immediately preceding the one resulting in cardiovascular collapse.

Effects of repeat bolus ethanol injections on cardiopulmonary hemodynamic changes during embolotherapy of arteriovenous malformations of the extremities

PURPOSE

This study was designed to investigate the effects of repeat bolus absolute ethanol injections on cardiopulmonary hemodynamic changes during ethanol embolotherapy of inoperable congenital arteriovenous (AV) malformations in the extremities.

MATERIALS AND METHODS

Thirty adult patients (14 male, 16 female; age range, 22-51 years) who underwent ethanol embolotherapy of extremity AV malformations were enrolled in the study. A pulmonary artery catheter was used to measure hemodynamic profiles at baseline (T(baseline)), immediately before (T(pre)) and after (T(post)) a bolus injection of absolute ethanol, at the time of the maximum mean pulmonary arterial pressure (PAP) value during a session (T(highest)), 10 minutes after the final injection (T(final)), and after restoration of spontaneous breathing (T(resp)).

RESULTS

The systolic, mean, and diastolic PAP (P < .01, P < .01, and P < .01, respectively) and the systemic vascular resistance index (P < .05) and pulmonary vascular resistance index (PVRI; P < .05) of T(highest) and T(resp) were significantly higher than values for T(final). The volume of a single bolus injection of absolute ethanol from 0.023 to 0.175 mL/kg of body weight showed that the systolic PAP (P = .02), pulmonary capillary wedge pressure (P = .02), and PVRI (P < .01) significantly increased in accordance with the increased single volume of absolute ethanol. A significant increase of the right ventricular end-diastolic volume index and right ventricular end-systolic volume index were observed at a dose of more than 0.14 mL/kg of body weight for a single bolus injection of absolute ethanol.

CONCLUSIONS

During ethanol embolotherapy of extremity AV malformations, significant hemodynamic changes can arise during a bolus injection of absolute ethanol. Cardiopulmonary hemodynamic profiles should be monitored closely after a bolus injection of more than 0.14 mL/kg of body weight of absolute ethanol.

A rare case of combined soft-tissue and intraosseous arteriovenous malformation of the hand with diffuse periosteal elevation: imaging appearances

Arteriovenous malformations are uncommon congenital lesions of the hand. Although present at birth, they usually manifest later in life. Ultrasonography, MRI and digital subtraction angiography play an important role in the diagnosis of these lesions. We report the imaging appearances of an unusual case of combined soft-tissue and intraosseous arteriovenous malformation (AVM) of the hand with marked periosteal elevation in a 12-year-old child. Although associated skeletal changes are common, diffuse periosteal elevation owing to direct communication of the AVM with the subperiosteal space has not, to the best of our knowledge, been reported previously.

Intraosseous embolotherapy of central arteriovenous malformations in the jaw: long-term experience with 8 cases

PURPOSE

To investigate the long-term effects of direct intraosseous histoacryl embolotherapy on central arteriovenous malformations (AVMs) of the jaw.

MATERIALS AND METHODS

Eight patients with central AVMs of the jaw (3 in the maxilla and 5 in the mandible) were treated with direct intraosseous histoacryl injection. These AVMs exhibited cystic radiolucency, with (n = 5) or without (n = 3) honeycombed component. On angiography, all the AVMs exhibited a large intraosseous nidus with multiple suppliers and drainages. The intraosseous lesions were percutaneously punctured with an 18- to 20-gauge needle, and NBCA diluted 30% to 40% with iodized oil was injected during venous compression.

RESULTS

Postembolic arteriograms showed that all the AVMs were completely or nearly completely devascularized after single or multiple injections at the initial treatment. The follow-up period ranged from 3 to 8 years. Two AVMs experienced postembolic curettage and were anatomically cured. Three AVMs were anatomically cured after 1 to 3 sessions of embolotherapy. The other 3 AVMs were clinically cured after 1 (n = 2) to 4 (n = 1) sessions of embolotherapy. There were no procedure-related severe complications.

CONCLUSIONS

Direct intraosseous glue embolotherapy can be a simple and safe technique for endovascular management of central AVMs in the jaw and is particularly effective in an emergency. Complete reossification of the intraosseous nidus can be anticipated if a complete occlusion is obtained.

Ethanol embolization of auricular arteriovenous malformations: preliminary results of 17 cases

BACKGROUND AND PURPOSE

Because of the relatively rare and extremely varied clinical presentations, arteriovenous malformations (AVMs) involving the auriculae are technically challenging clinical entities to diagnose and, ultimately, manage. The purpose of our study was to present our initial experience of ethanol embolization in a series of 17 patients with auricular AVMs and assess the interim therapeutic outcomes of this method.

MATERIALS AND METHODS

Our study group consisted of 17 patients. Transcatheter arterial embolization and/or direct percutaneous puncture embolization were performed. Pure or diluted ethanol was manually injected. Follow-up evaluation was obtained on the basis of physical examination and angiography at 3- to 4-month intervals and telephone questionnaire at 1-month intervals in all patients.

RESULTS

During the 29 ethanol embolization procedures, the amount of ethanol used ranged from 4 to 65 mL. The obliteration of ulceration, hemorrhage, pain, infection, pulsation, and bruit in most of the patients was obtained. The reduction of redness, swelling, and warmth was achieved in all of the patients, and 15 of the patients achieved downstaging of the Schobinger status. According to the angiographic findings, AVMs were devascularized 100% in 3 patients, 76% to 99% in 5 patients, 50% to 75% in 6 patients, and less than 50% in 3 patients. The most common complications were reversible necrosis and blister.

CONCLUSIONS

Ethanol embolization has proved efficacious and safe in the treatment of auricular AVMs and has the potential to be accepted as the primary mode of therapy in the management of these lesions.

Radiation therapy for intractable bleeding in extremity arteriovenous malformation: considerations on a clinical case

Arteriovenous malformations are rare clinicopathological entities with varied distribution and a constellation of symptoms. In the extremities they are usually associated with dermatological manifestations, such as angiodermatitis with a potential risk of torrential haemorrhage. Surgical resection is a morbid procedure. Transcatheter embolization and sclerotherapy is an attractive alternative to surgical resection. However, proper case selection is a prerequisite and may not be possible in all the cases. The case reported here is a paradigm of a complex and extensive vascular malformation with torrential haemorrhage where a unique therapeutic approach of radiation therapy was used as an alternative to morbid surgery after embolization and sclerotherapy failure.

Ethanol embolization of arteriovenous malformations of the mandible

BACKGROUND AND PURPOSE

Absolute ethanol was reported as an effective embolization of arteriovenous malformations (AVMs), but its use to treat AVMs in the mandible is not yet well established. Here, we present our clinical experience on treatment of mandibular AVMs with absolute ethanol.

MATERIALS AND METHODS

Eight consecutive patients with symptomatic AVMs of the mandible between August 2007 and September 2008 were enrolled in this study group. Among them, 6 patients underwent direct puncture embolization with absolute ethanol combined with coils, 1 patient underwent direct puncture embolization with absolute ethanol only, and the last patient had transarterial embolization with absolute ethanol alone. The use of coils decreased the flow and volume of the nidus, and then absolute ethanol embolization was directed against and obliterated the nidus completely. The procedure was performed with the patients under general anesthesia with nasal intubation, and the vital signs of the patients were constantly monitored during the injection of absolute ethanol. The total amount of absolute ethanol used per session was less than 1 mL/kg of body weight.

RESULTS

A total of 11 ethanol embolizations were performed on 8 patients, including 3 sessions with transarterial microcatheterization and 8 with direct puncture embolization. A venogram and control arteriogram performed immediately after the procedure were both obtained, which documented a significant thrombosis of the lesion in all patients. Follow-up examinations revealed that oral bleeding was controlled, the expansion of the external jugular vein in 5 cases was obliterated, and satisfactory shrinkage of the facial swelling was achieved. Follow-up angiography (mean, 4.2 months) was available in 4 patients, and there was no angiographic recurrence of the lesions. There were 3 cases with minor complications.

CONCLUSIONS

On the basis of our experience, treatment of AVMs in the mandible with absolute ethanol is a feasible, safe, and highly effective method.

MRI characteristics and classification of peripheral vascular malformations and tumors

Vascular malformations and tumors comprise a broad spectrum of lesions that can cause significant morbidity and even mortality in children and adults. Classification of vascular malformations into high flow and low flow has significant impact on management since the main treatment of the former is transarterial embolization and the later percutaneous sclerotherapy. Magnetic resonance imaging (MRI) is a noninvasive effective tool for imaging and classification of vascular malformations based on the presence of lobulated masses, signal voids, and hemodynamic flow characteristics. MRI also provides details about anatomic extent of the lesion, proximity to vital structures, and involvement of multiple tissue planes. The prototype of vascular tumors is infantile hemangioma with its typical involution after a proliferative phase during infancy. Hemangioma appears as a distinct intensely enhancing soft tissue mass with enlarged feeding arteries and draining veins. Less common vascular tumors include congenital hemangioma, kaposiform hemangioendothilioma, angiolipoma, angiosarcoma, and hemangiopericytoma.

MR imaging-guided percutaneous sclerotherapy of peripheral venous malformations with a clinical 1.5-T unit: a pilot study

PURPOSE

To evaluate the feasibility of magnetic resonance (MR) imaging-guided percutaneous sclerotherapy of venous malformations (VMs) by using a clinical 1.5-T MR unit and the safety and therapeutic outcome of the performed procedures.

MATERIALS AND METHODS

This is a prospective pilot study with ethical approval and written informed patient consent. Ten MR imaging-guided percutaneous sclerotherapy treatments were performed in 10 patients (one male and nine female patients; age range, 16-47 years; mean age, 30.3 years) with a VM in the foot and/or ankle (n = 5), calf (n = 2), thigh and/or knee (n = 2), and elbow (n = 1). MR imaging was used for needle insertion guidance and real-time monitoring of the injection process by using three-dimensional fast spoiled gradient-echo MR sequences (repetition time msec/echo time msec = 3.7-5.2/1.1-1.6, flip angle = 35 degrees) and meglumine gadoterate/ethanol solutions as the sclerosing agent. The technical success (ie, absence of technical problems, number of needle position corrections) was systematically evaluated along with safety aspects (ie, absence of complications) and the therapeutic outcome (eg, VM volume decrease, relief of symptoms) during a 1-year follow-up period.

RESULTS

MR imaging-guided sclerotherapy was technically successful in all patients. A mean of 2.5 +/- 1.85 (range, 1-6) needle position corrections were needed for correct needle placement. The distribution of the sclerosing agent (mean amount, 10.5 mL; range, 0.8-33.0 mL) was clearly visible with real-time MR monitoring. One patient developed a compartment syndrome, which was managed with surgery. No other complications were observed. VM volumes significantly decreased by 53% (range, 24%-86%; P = .02) 12 weeks after therapy. Nine of the 10 patients (90%) noted an improvement of symptoms.

CONCLUSIONS

In this limited preliminary series, 1.5-T MR imaging-guided percutaneous sclerotherapy for the treatment of VMs was feasible with a high degree of technical success, was relatively safe, and had a good therapeutic outcome after 1 year.

Ethanol sclerotherapy for the management of craniofacial venous malformations: the interim results

Objective

We wanted to evaluate the safety and feasibility of ethanol sclerotherapy for treating craniofacial venous malformations (CVMs).

Materials and Methods

From May 1998 to April 2007, 87 patients (40 men and 47 women; age range, 2-68 years) with CVMs underwent staged ethanol sclerotherapy (range, 1-21 sessions; median number of sessions, 2) by the direct puncture technique. Clinical follow up (range, 0-120 months; mean follow up, 35 months; median follow up, 28 months) was performed for all the patients. Therapeutic outcomes were established by evaluating the clinical outcome of the signs and symptoms in all patients, as well as the degree of devascularization, which was determined on the follow-up imaging, in 71 patients.

Results

A total of 305 procedures with the use of ethanol were performed in 87 patients. Follow-up imaging studies were performed for 71 of 87 patients. Twenty-three (32%) of the 71 patients showed excellent outcomes, 37 patients (52%) showed good outcomes and 11 patients (16%) showed poor outcomes. Ethanol sclerotherapy was considered effective for 60 patients. All the minor complications such as bulla (n = 5) healed with only wound dressing and observation. Any major complication such as skin necrosis did not develop.

Conclusion

Percutaneous ethanol sclerotherapy is an effective, safe treatment for CVMs.

Prediction of the effect of injected ethanol on pulmonary arterial pressure during sclerotherapy of arteriovenous malformations: relationship with dose of ethanol

PURPOSE

To prospectively evaluate the effect of injected ethanol on pulmonary artery pressure during embolosclerotherapy of arteriovenous malformations (AVMs).

MATERIALS AND METHODS

This prospective study was conducted in 16 male and 14 female patients (37 sessions; mean age, 34 years; age range, 17-67 years) with AVMs during a 2-year period. The authors measured pulmonary artery pressure via a pulmonary artery catheter and ethanol levels from the pulmonary and radial arteries simultaneously within 3 minutes after each ethanol injection. The authors analyzed the relationship between pulmonary artery pressure and ethanol levels obtained from pulmonary and radial arteries with respect to both single and cumulative doses of ethanol injected. Retrospectively, patients were divided into two groups-those treated with and those treated without vascular occlusion techniques.

RESULTS

The radial arterial ethanol level showed good correlation with the pulmonary arterial ethanol level (r = 0.7). Single dose per injection was statistically related with pulmonary artery pressure (r = 0.5 vs 0.1 and P < .05 vs .29, respectively, in patients treated without and patients treated with vascular occlusion techniques), and the correlation coefficient between cumulative dose and pulmonary artery pressure was 0.2 and 0.3 in respective cases (P < .05 for both). The mean pulmonary artery pressure correlated with pulmonary arterial ethanol level irrespective of the use of vascular occlusion (r = 0.6 for both groups).

CONCLUSIONS

Pulmonary artery pressure reflected the pulmonary arterial ethanol level and was positively related to the dose of ethanol. Single dose per injection was predictive of pulmonary artery pressure only in patients treated without vascular occlusion techniques.

Peripheral arteriovenous malformations with a dominant outflow vein: results of ethanol embolization

Objective

To assess retrospectively the treatment results of ethanol embolization of peripheral arteriovenous malformations (AVMs) with a dominant outflow vein (DOV).

Materials and Methods

Nineteen patients who had peripheral AVMs with a DOV were enrolled in this study (mean age, 29.7 years; range, 15-42 years). Fifty-one ethanol embolizations (mean, 2.7; range, 1-8) were performed by direct puncture (n = 29), the transarterial approach (n = 13), the transvenous approach (n = 5), or a combination of methods (n = 4) under general anesthesia. Coil and/or core-removed guide wire embolization of the DOV or another flow occlusion technique (i.e., use of an external pneumatic pressure cuff) to achieve vascular stasis were required in all patients during ethanol embolization. Clinical follow-up (mean, 22.2 months; range, 1-53 months) was performed for all patients, and imaging follow-up (mean, 22.1 months; range, 2-53 months) from the last treatment session was performed for 14 patients. The therapeutic outcome (cure, improvement, no change, or aggravation) was assessed according to the clinical response and the degree of devascularization at angiography.

Results

Ethanol embolization was considered as an effective procedure in all patients. Thirteen (68%) of 19 patients were cured and six displayed improvement. Three of six patients with improvement needed further treatment sessions for residual AVMs. Four patients (21%) experienced a total of eight complications. Five complications (three events of a distal embolism and one event each of a urinary bladder necrosis and a brain infarct related to the accidental cannulation of the common carotid artery during insertion of the Swan-Ganz catheter) were major and three complications (skin necrosis) were minor.

Conclusion

Peripheral AVMs with a DOV can be effectively treated with a high cure rate by the use of ethanol embolization alone or in conjunction with the use of coil and/or core-removed guide wire embolization.

Venous malformations: classification, development, diagnosis, and interventional radiologic management

Venous malformations are categorized as low-flow vascular malformations within the domain of vascular anomalies and are the most common vascular malformation encountered clinically. Venous malformations are by definition present at birth, undergo pari passu growth, and present clinically because of symptoms related to mass effect or stasis. Although diagnosis can usually be made by clinical history and examination, differentiation from other vascular and nonvascular entities often requires an imaging work-up that includes ultrasound, CT, MR imaging, and diagnostic phlebography. All decisions regarding imaging work-up and decision to treat must be coordinated though referral and discussions with a multidisciplinary team and be based on clearly defined clinical indications. Percutaneous image-guided sclerotherapy has become the mainstay of treatment for venous malformations and involves the introduction of any one of a number of endothelial-cidal sclerosants into the vascular spaces of the lesion, with each sclerosant possessing its own unique spectrum of advantages and disadvantages.

[Imaging in diagnosis and treatment of vascular lesions of the hand]

Vascular lesions of the hand are challenging for diagnosis and treatment. These lesions are far more common than malignant tumors. Clinical presentation may be confusing and correct identification by imaging is sometimes mandatory. Standard X-rays and doppler ultrasound examination are the first modalities to be used. Doppler ultrasound help to characterize the lesion or/and to assess the flow velocity within the lesion. It allows to separate the high flow lesions (hemangioma, arteriovenous malformation) from the low or no flow lesions (venous malformation, cystic lymphangioma). MR imaging is the gold examination to define the size and the extension of the lesion to adjacent structures. Careful clinical and imaging evaluation and multidisciplinary staff decision are crucial before to propose embolotherapy and/or surgical treatment. In case of persistent doubt, a biopsy must be required. AVM must be excluded before to propose this biopsy sample. Interventional radiology can be used alone or in combination with surgery to treat vascular malformation (arteriovenous, lymphatic, venous, or mixed). Embolisation may either be done by percutaneous approach (all malformations) or by intravascular catheterization (arteriovenous malformation). Hemangioma is a benign tumor which most often spontaneously involutes with age. Vascular malformations of the hand are difficult to eradicate completely either with embolization or surgery or both. Recurrences are frequent. Management in multidisciplinary staff is mandatory and long follow-up is needed.

Ethanol embolotherapy of pelvic arteriovenous malformations: an initial experience

Objective

We retrospectively assessed the results of performing ethanol embolization for pelvis arteriovenous malformations (AVMs).

Materials and Methods

During the past 10 years, eight patients (8 females, age range: 27-52 years) with AVMs in the pelvic wall (n = 3) and uterus (n = 5) underwent staged ethanol embolizations (range: 1-5, mean: 2.5) under general anesthesia. Ethanol embolization was performed by the use of the transcatheter and/or direct puncture techniques. Clinical follow-up was performed for all of the patients, and imaging follow-up was available for seven patients. The therapeutic outcomes were established by evaluating the clinical outcome of the signs and symptoms, as well as the degree of devascularization observed on post-procedural angiography.

Results

During the 20 sessions of ethanol embolization, the solitary transarterial approach was used 14 times, the transvenous approach was used three times and direct puncture was used once. For two patients, the transarterial and transvenous or direct puncture approaches were used together in one session. For four patients, ethanol and coils were used as embolic agents, and n-butyl cyanoacrylate (NBCA) and ethanol were used in one patient. Seven (88%) of eight patients were cured of their AVMs and one patient (12%) displayed improvement. Major complications were seen in two patients (25%).

Conclusion

Ethanol embolization is effective for the treatment of pelvic arteriovenous malformations, though there is a chance of a major complication.

Anesthesia for endovascular neurosurgery and interventional neuroradiology

This review outlines the roles of anesthesiologists in the management of patients undergoing invasive endovascular procedures to treat vascular diseases, primarily of the central nervous system. This practice usually is termed interventional neuroradiology or endovascular neurosurgery. The discussion emphasizes perioperative and anesthetic management strategies to prevent complications and minimize their effects if they occur. Planning anesthetic and perioperative management is predicated on understanding the goals of the therapeutic intervention and anticipating potential problems.

The role of neuroendovascular therapy for the treatment of brain arteriovenous malformations

Neuroendovascular embolization represents a critical component of the multidisciplinary management of cerebral arteriovenous malformations. Safe and effective embolization may be performed only in the context of a well-designed, rational treatment plan that is fundamentally based on a clear understanding of the natural history of the lesion, as well as the cumulative risks of multimodality treatment. This article outlines the role of neuroendovascular embolization in arteriovenous malformation therapy with a specific emphasis on decision making in the context of formulating a treatment plan. The authors also provide a summary of the available embolic agents and their technical application, potential intraprocedural and periprocedural complications, and postprocedural management.

Principles and techniques of transcatheter embolotherapy for peripheral vascular lesions

Transcatheter embolotherapy (TCE), a common procedure for interventional radiologists, comprises transcatheter delivery of embolic agents into target vessels in order to eliminate lesions or lesion-associated symptoms. Good knowledge of delivery catheters and embolic agents is essential to optimize embolization techniques and to obtain the desired therapeutic outcomes. In this review, we describe the principles and techniques of TCE for peripheral arterial and venous lesions featuring visceral aneurysms, peripheral and pulmonary arteriovenous malformations (AVMs), and varicoceles.

Traitement radiologique des malformations artérioveineuses périphériques

Management of high-flow arteriovenous malformation remain often problematic. Complete eradication of the nidus is the only potential cure, but this, however, is often difficult if not impossible. Frequently, a multidisciplinary approach is required. In these article, techniques and results of the endovascular management of MAV are discussed.

Arteriovenous Malformations of the Body and Extremities: Analysis of Therapeutic Outcomes and Approaches According to a Modified Angiographic Classification

PURPOSE

To propose a modified angiographic classification for peripheral arteriovenous malformations (AVMs) and to determine its value for assessing therapeutic outcomes and approaches to ethanol embolization of AVMs in the body and extremities.

METHODS

AVMs of the trunk and extremities were categorized according to the angiographic morphology of the nidus: type I (arteriovenous fistulae), type II (arteriolovenous fistulae), type IIIa (arteriolovenulous fistulae with non-dilated fistula), and type IIIb (arteriolovenulous fistulae with dilated fistula). Sixty-six patients (41 women; mean age 28.3 years, range 5-53) with inoperable AVMs in the body and extremities who underwent staged ethanol embolizations were retrospectively analyzed. Therapeutic outcomes and approaches were evaluated according the above classification system.

RESULTS

The 66 AVMs were composed of 30 (45%) type IIIb, 13 (20%) type II, 12 (18%) mixed types IIIa and IIIb, 9 (14%) mixed types II and IIIb, and 2 (3%) type IIIa. Ethanol embolization was most effective for type II (100%), and more effective for type IIIb (83%) than for type IIIa or mixed types (< or = 50%). Despite the use of the transarterial approach, direct puncture and transvenous approaches were more relevant for treating type II AVMs. Only the transarterial approach was used for treating type IIIa; both direct puncture and transarterial approaches were used for treating the other types.

CONCLUSION

The described angiographic classification provides considerable information concerning the characteristics of AVMs in the body and extremities, the optimal therapeutic approach, and the likely therapeutic outcome.

Classification, diagnosis, and interventional radiologic management of vascular malformations

Vascular anomalies are comprised of either hemangiomas or vascular malformations.Low-flow vascular malformations can be divided into capillary, venous, and lymphatic types and are usually present at birth, undergo pari passu growth, and produce symptoms related to mass effect or stasis. High-flow malformations are comprised pre-dominantly of arteriovenous malformations that follow a more aggressive clinical course of hyperemia, adjacent mass effect, steal phenomenon, tissue destruction, and ultimately high output failure. Ultrasound, CT, nuclear medicine, angiography, and particularly MRI have greatly enhanced diagnostic accuracy and provide detailed information for percutaneous and surgical treatment planning and an objective means of following therapeutic efficacy. Interventional radiologic percutaneous sclerotherapy for low-flow lesions and embolosclerotherapy for high-flow lesions with or without adjunctive surgical intervention have become the mainstay of therapy.

Peripheral vascular malformations: imaging, treatment approaches, and therapeutic issues

Peripheral vascular malformations are now described according to some accepted guidelines, and the principle of proper treatment (nidus ablation) is becoming clear. An appropriate classification scheme for vascular anomalies and definite indications for treatment are important to successful treatment overall. The findings from noninvasive imaging (ie, Doppler ultrasonography, computed tomography, or magnetic resonance imaging) in association with clinical findings are critical in establishing the diagnosis, evaluating the extent of the malformation, and planning appropriate treatment. Direct opacification of the nidus is useful, not only in making a correct diagnosis, but also in treating the lesion with sclerotherapy. In most cases, conservative treatment is recommended, but when a patient suffers clinical complications (eg, ulceration, pain, hemorrhage, cardiac failure, or unacceptable cosmetic consequences), the nidus sclerotherapy becomes mandatory. If the vascular malformation has blood outflow to a drainage vein during nidus opacification, flow control (with balloon occlusion, tourniquet, or embolization) is necessary to achieve sclerosant stasis within the nidus. Embolotherapy (with a coil, n-butyl cyanoacrylate, or small particles) should be used for subsequent multifaceted palliative therapy. A multi-disciplinary approach is needed in the treatment of a high-flow lesion, and a dedicated team approach is necessary for appropriate management in most cases.

Contrast Material–enhanced Visualization of the Ablation Medium for Magnetic Resonance– monitored Ethanol Injection Therapy: Imaging and Safety Aspects

PURPOSE

This study was performed to test whether the dissociation rate of free Gd3+ ions from gadoterate meglumine is significantly increased when the contrast agent is dissolved in ethanol and whether the magnetic resonance (MR) signal of gadolinium/ethanol solutions is enhanced to a degree that promises reliable detection during MR imaging-guided intralesional administration, such as for the treatment of low-flow venous malformations.

MATERIALS AND METHODS

The apparent gadoterate meglumine-induced enhancement of the longitudinal proton relaxation rate of sterile ethanol/water solutions, stored at a temperature of 24 degrees C +/- 5 degrees C in the dark, was monitored for 2 weeks. The content of dissociated Gd3+ ions was determined after 6 and 8.5 months of storage. The signal difference between contrast agent/ethanol solutions and muscle tissue was assessed with imaging at 0.5 T and 1.5 T.

RESULTS

Commercialized gadoterate meglumine diluted with 94% ethanol was not shown to have released toxic Gd3+ during storage times that exceed its physiologic circulation and excretion times after intravenous injection by a factor of more than 100. A maximum dissociation rate of 0.05% per month was estimated from the detection limit of the analysis. The apparent molar relaxivity of the contrast agent in the mixtures varied by less than 0.1 L/mmol per second with no temporal trend. Gradient-echo ethanol/muscle contrast increased with Gd concentrations to maximums of 15 mmol/L (at 0.5 T) and 25 mmol/L (at 1.5 T).

CONCLUSIONS

Neither limited solubility nor release of Gd3+ ions could be identified as a general safety hazard associated with the application of gadoterate meglumine/ethanol solutions at Gd concentrations of 0.5-25 mmol/L, and such ablation mixtures could be efficiently and reliably visualized.

Dynamic MRI for Distinguishing High-Flow from Low-Flow Peripheral Vascular Malformations

OBJECTIVE

The purpose of our study was to assess the usefulness of dynamic MRI in distinguishing high-flow vascular malformations from low-flow vascular malformations, which do not need angiography for treatment.

SUBJECTS AND METHODS

Between September 2001 and January 2003, 16 patients who underwent conventional and dynamic MRI had peripheral vascular malformations (six high- and 10 low-flow). The temporal resolution of dynamic MRI was 5 sec. Time intervals between beginning of enhancement of an arterial branch in the vicinity of a lesion in the same slice and the onset of enhancement in the lesion were calculated. We defined these time intervals as "artery-lesion enhancement time." Time intervals between the onset of enhancement in the lesion and the time of the maximal percentage of enhancement above baseline of the lesion within 120 sec were measured. We defined these time intervals as "contrast rise time" of the lesion. Diagnosis of the peripheral vascular malformations was based on angiographic or venographic findings.

RESULTS

The mean artery-lesion enhancement time of the high-flow vascular malformations (3.3 sec [range, 0-5 sec]) was significantly shorter than that of the low-flow vascular malformations (8.8 sec [range, 0-20 sec]) (Mann-Whitney test, p < 0.05). The mean maximal lesion enhancement time of the high-flow vascular malformations (5.8 sec [range, 5-10 sec]) was significantly shorter than that of the low-flow vascular malformations (88.4 sec [range, 50-100 sec]) (Mann-Whitney test, p < 0.01).

CONCLUSION

Dynamic MRI is useful for distinguishing high-flow from low-flow vascular malformations, especially when the contrast rise time of the lesion is measured.

Vascular masses of the head and neck

The classification, clinical presentation, natural history and imaging appearances of vascular masses of the head and neck are reviewed. The radiological appearances of congenital vascular masses (infantile haemangiomas and other congenital vascular tumours, high-flow and low-flow vascular malformations), acquired vascular masses (benign and malignant tumours, non-neoplastic lesions) and other hypervascular masses are described and illustrated, together with consideration of image-guided interventions.

Radiofrequency ablation of a recanalized renal arteriovenous malformation

Radiofrequency (RF) ablation is becoming established as a method of treatment of small renal neoplasms. Successful RF ablation of a renal arteriovenous malformation (AVM) was performed in a patient who had previously undergone coil embolization and experienced hematuria after the feeding vessels recanalized. The 3.5-cm lesion was successfully treated with RF ablation, resulting in cessation of hematuria. At follow-up, there was no residual enhancement of the AVM on computed tomography and the lesion had decreased in size.

Imaging of head and neck venous malformations

Venous malformations (VMs) are non proliferative lesions that consist of dysplastic venous channels. The aim of imaging is to characterise the lesion and define its anatomic extent. We will describe the plain film, ultrasound (US) (including colour and duplex Doppler), computed tomography (CT), magnetic resonance imaging (MRI), conventional angiographic and direct phlebographic appearances of venous malformations. They will be illustrated at a number of head and neck locations, including orbit, oral cavity, superficial and deep facial space, supraglottic and intramuscular. An understanding of the classification of such vascular anomalies is required to define the correct therapeutic procedure to employ. Image-guided sclerotherapy alone or in combination with surgery is now the first line treatment option in many cases of head and neck venous malformations, so the radiologist is now an integral part of the multidisciplinary management team.