MR-guided percutaneous sclerotherapy of low-flow vascular malformations: Clinical experience using a 1.5 tesla MR system

Magnetic resonance - guided treatment of low-flow vascular malformations and the technologies to potentiate adoption

Vascular malformations are congenital, non-neoplastic lesions that arise secondary to defects in angiogenesis. Vascular malformations are divided into high-flow (arteriovenous malformation) and low-flow (venous malformations and lymphatic malformations). Magnetic resonance imaging (MRI) is the standard for pre-and post-intervention assessments, while ultrasound (US), X-ray fluoroscopy and computed tomography (CT) are used for intra-procedural guidance. Sclerotherapy, an image-guided therapy that involves the injection of a sclerosant directly into the malformation, is typically the first-line therapy for treating low-flow vascular malformations. Sclerotherapy induces endothelial damage and necrosis/fibrosis with eventual involution of the malformation. Image-guided thermal therapies involve freezing or heating target tissue to induce cell death and necrosis. MRI is an alternative for intra-procedural guidance and monitoring during the treatment of vascular malformations. MR can provide dynamic, multiplanar imaging that delineates surrounding critical structures such as nerves and vasculature. Multiple studies have demonstrated that MR-guided treatment of vascular malformations is safe and effective. This review will detail (1) the use of MR for the classification and diagnosis of vascular malformations, (2) the current literature surrounding MR-guided treatment of vascular malformations, (3) a series of cases of MR-guided sclerotherapy and thermal ablation for the treatment of vascular malformations, and (4) a discussion of technologies that may potentiate interventional MRI adoption including high intensity focused ultrasound and guided laser ablation.

Percutaneous MR Imaging-Guided Laser Ablation for the Treatment of Symptomatic Cervicofacial Vascular Malformations

PURPOSE

To evaluate the safety and effectiveness of percutaneous magnetic resonance (MR) imaging-guided laser ablation for the treatment of symptomatic soft tissue vascular malformations (VMs) in the face and neck.

MATERIALS AND METHODS

An institutional review board-approved retrospective review was undertaken of all consecutive patients who underwent MR imaging-guided and monitored laser ablation for treatment of symptomatic, cervicofacial soft tissue VM. Preablation and postablation MR imaging findings were independently reviewed. Preablation and postablation VM sizes were documented. Preablation T2 signal characteristics and enhancement patterns as well as postablation change in both signal and enhancement were semiquantitatively assessed. Changes in VM size were compared using a paired t test.

RESULTS

Thirteen patients (women, 9; age, 14.5-69.5 years) with 13 VMs were treated for moderate-to-severe pain (n = 4), swelling/mass effect (n = 8), or predominantly cosmesis (n = 1) with 22 total ablation sessions. The baseline maximum VM diameter was 5.7 cm ± 4.2. At baseline, all VMs (100%) demonstrated variable T2-weighted signal hyperintensity and enhancement. For painful VM, the baseline pain score was 8 ± 1. Clinical follow-up was available for 10 patients. Of patients with available follow-up, 3 (100%) treated for moderate-to-severe pain and 7 (100%) treated for swelling/mass effect reported subjective complete or partial symptomatic relief. The patient treated predominantly for cosmetic reasons was lost to follow-up. Two patients (15.4%) experienced minor adverse events by the Society of Interventional Radiology standards. There were no major adverse events.

CONCLUSIONS

MR imaging-guided and monitored percutaneous laser ablation is safe and effective for the treatment of symptomatic, cervicofacial VMs.

Percutaneous MR Imaging-Guided Laser Ablation and Cryoablation for the Treatment of Pediatric and Adult Symptomatic Peripheral Soft Tissue Vascular Anomalies

PURPOSE

To evaluate the safety and effectiveness of percutaneous magnetic resonance (MR) imaging-guided laser ablation and cryoablation for the treatment of symptomatic soft tissue vascular anomalies (VAs) of the trunk and extremities.

MATERIALS AND METHODS

An institutional review board-approved retrospective review was undertaken of all pediatric and adult patients who underwent MR imaging-guided and monitored laser ablation and/or cryoablation for the treatment of symptomatic peripheral soft tissue VA. Preablation and postablation MR imaging was independently reviewed. Pain scores on the visual analog scale (0 to 10) and self-reported subjective symptomatic improvement were assessed. Change in VA size and pain scores were compared using a paired t test.

RESULTS

Thirty patients (24 females; age, 10-75 years) with 34 VAs were treated for moderate to severe pain (n = 27) or swelling/mass effect (n = 3) with 60 total ablation sessions. The baseline maximum VA diameter was 9.5 cm ± 8.6. At baseline, all VAs (100%) demonstrated variable T2-weighted signal hyperintensity and enhancement. The baseline pain score was 6.4 ± 1.6. Clinical follow-up was available for 23 patients. At a mean follow-up time of 12.2 months ± 10.1, 19 of 20 (95%) patients treated for pain and 2 of 3 (67%) patients treated for swelling/mass effect reported partial or complete symptomatic relief. There was a significant decrease in the postablation pain scores (-5.7 ± 1.0, P < .001) and maximum VA size (-2.3 cm ± 2.7, P = .004), with >50% reduction in VA T2 signal (59%) and enhancement (73%). Nine of 30 (30%) patients experienced minor complications.

CONCLUSIONS

MR imaging-guided and monitored percutaneous laser ablation and cryoablation appear to be safe and effective for the treatment of symptomatic peripheral soft tissue VAs.

Development and Preliminary Validation of the Patient-Reported Outcome Measure for Vascular Malformation Questionnaire: A Prospective Cohort Study

PURPOSE

To develop and validate the Patient-Reported Outcome Measure for Vascular Malformation (PROVAM) questionnaire to assess the health-related quality of life in patients with vascular malformations.

MATERIALS AND METHODS

We developed and validated PROVAM using a mixed methods design during a prospective clinical trial at a vascular anomalies clinic. From July 2019 to February 2020, 108 consecutive patients completed 130 questionnaires. The 30-item instrument assessed the domains of pain, emotional/social well-being, functional impact, and treatment satisfaction. Two additional items assessed ease of understanding and relevance. The primary outcomes of instrument reliability and validity were evaluated across several indices. The secondary outcome of responsiveness evaluated total score changes for patients who completed questionnaires both before and after treatment.

RESULTS

Instrument reliability, as measured by Cronbach alpha, was ≥0.79 for pain, emotional/social well-being, and functional impact domains. Primary domain structure was confirmed by factor analysis (P <. 001) and convergent construct validity for all but 1 Likert scale item. In the subgroup analysis of 13 participants who completed PROVAM before and after treatment, instrument responsiveness, as measured by the total score, showed a significant decrease (median, -10 points; interquartile range [IQR], -3 to -16; P = .04). Participants found the questions easy to understand (median, 5 points; IQR, 4-5 on a 5-point scale) and relevant (median score, 4; IQR, 3-5).

CONCLUSIONS

Preliminary data support the reliability and validity of PROVAM in measuring the health-related quality of life in patients with vascular malformations.

MRI-guided percutaneous sclerotherapy of venous malformations: initial clinical experience using a 3T MRI system

PURPOSE

Venous malformations (VMs) are low-flow vascular anomalies that are commonly treated with image-guided percutaneous sclerotherapy. Although many VMs can be safely accessed and treated using ultrasonography and fluoroscopy, some lesions may be better treated with magnetic resonance imaging (MRI)-guided sclerotherapy. The aim of this study is to evaluate the feasibility, efficiency, and outcomes of MRI-guided sclerotherapy of VMs using a 3T MRI system.

METHODS

Six patients with VMs in the neck (n = 2), chest (n = 1), and extremities (n = 3) underwent sclerotherapy with 3T MRI guidance. Feasibility was assessed by calculating the technical success rate and procedural efficiency. Efficiency was evaluated by using planning, targeting, intervention, and total procedure times. Outcomes were assessed by measuring VM volumes before and after sclerotherapy, patient-reported pain scores, and occurrence of complications.

RESULTS

Technical success was achieved in all 6 procedures. There was a non-significant 30% decrease in mean VM volume after the procedure (P = .350). The procedure resulted in a decrease in mean pain score (on an 11-point scale) of 2.6 points (P = .003). After the procedure, 4 patients reported complete pain resolution, 1 reported partial pain resolution, and 1 reported no change in pain. Procedural efficiency was consistent with similar sclerotherapy procedures performed at our institution. There were no major or minor complications.

CONCLUSION

3T MRI guidance is feasible for percutaneous sclerotherapy of VMs, with promising initial technical success rates, procedural efficiency, and therapeutic outcomes without complications.

MR-Guided Sclerotherapy for the Treatment of Low-Flow Vascular Malformations

Low-flow vascular malformations are congenital lesions that can occur throughout the body. Treatment of these lesions is indicated to ameliorate pain, cosmetic disfigurement, and functional impairment. The first-line treatment of low-flow vascular malformations is percutaneous sclerotherapy. Traditionally, sclerotherapy is performed with a combination of ultrasound and fluoroscopy. However, malformations that are deep in the abdomen and pelvis or are obscured by overlying fascia or scar may be difficult to be visualized with ultrasound and fluoroscopy. MR-guided sclerotherapy has emerged as an alternative modality that can be used to needle guidance and sclerosant monitoring. In this review, we discuss the historical and current use of MR-guided sclerotherapy for the treatment of low-flow vascular malformations.

Label-free photoacoustic imaging guided sclerotherapy for vascular malformations: a feasibility study

We used high-resolution photoacoustic imaging (PAI) to guide sclerotherapy of vascular malformations in an in vivo animal model. A focus-adjustable PAI system was developed. It can adapt to the imaging needs of different depths by adjusting the focus. Blood samples drawn before and after sclerosis were examined with PAI, which could distinguish whether or not the blood had been exposed to a sclerosing agent. Superficial and deep vessels in the animal model were examined in vivo to prove the feasibility of guiding sclerotherapy. We found that PAI can distinguish sclerotic vessels from normal vessels within a certain depth range. Our findings suggest the potential of PAI to find accurate injection points and to localize thrombi, making it possible to reduce the dosage of sclerosing agents.