Auh Whan Park

MR imaging of soft-tissue vascular malformations: diagnosis, classification, and therapy follow-up.

Vascular malformations and tumors comprise a wide, heterogeneous spectrum of lesions that often represent a diagnostic and therapeutic challenge. Frequent use of an inaccurate nomenclature has led to considerable confusion. Since the treatment strategy depends on the type of vascular anomaly, correct diagnosis and classification are crucial. Magnetic resonance (MR) imaging is the most valuable modality for classification of vascular anomalies because it accurately demonstrates their extension and their anatomic relationship to adjacent structures. A comprehensive assessment of vascular anomalies requires functional analysis of the involved vessels. Dynamic time-resolved contrast material-enhanced MR angiography provides information about the hemodynamics of vascular anomalies and allows differentiation of high-flow and low-flow vascular malformations. Furthermore, MR imaging is useful in assessment of treatment success and establishment of a long-term management strategy. Radiologists should be familiar with the clinical and MR imaging features that aid in diagnosis of vascular anomalies and their proper classification. Furthermore, they should be familiar with MR imaging protocols optimized for evaluation of vascular anomalies and with their posttreatment appearances. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.315105213/-/DC1.

Endovascular Therapy for Hepatic Artery Stenosis and Thrombosis Following Liver Transplantation

Purpose: To evaluate the effectiveness of endovascular management of steno-oclusive disease in liver transplants. Methods: Retrospective review of liver transplant recipients with hepatic artery stenosis (HAS) or thrombosis (HAT) was performed. The HAS group was treated with balloon angioplasty with selective stent placement. The HAT group was treated with catheter-directed thrombolysis. Primary, unassisted, and assisted patency and graft survival rates were calculated. Results: In all, 31 patients were identified (21 males; mean age, 51 years). A total of 25 of 31 (81%) patients had HAS and 6 of 31 (19%) had HAT. Collectively, a total of 35 endovascular procedures were performed to treat HAS in 25 patients. Overall technical success rate was 91%, with 11% major complication rate. Primary-assisted patency rate and graft survival at 6 and 12 months were 87% and 81%, and 76% and 72%, respectively. Only 1 successful thrombolysis of HAT was achieved. Conclusion: Endovascular management is effective for HAS but not for HAT.

Is fibromuscular dysplasia underdiagnosed? A comparison of the prevalence of FMD seen in CORAL trial participants versus a single institution population of renal donor candidates

Renal artery fibromuscular dysplasia (FMD) may be underdiagnosed. We evaluated the prevalence of FMD in CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) renal artery stent trial participants, in which FMD was an exclusion criterion for inclusion. We also evaluated the prevalence of FMD in a relatively healthy population of patients undergoing computed tomographic angiographic (CTA) screening for renal donor evaluation. All renal donor CTAs performed at our institution from January 2003 through November 2011 were retrospectively reviewed for the presence of FMD along with patient sex and age. These results were compared to angiographic core lab (ACL) findings for the CORAL trial. The CORAL ACL database contained 997 patients (mean age 69.3 years; 50% female). Fifty-eight (5.8%) CORAL trial patients (mean age 71.8 years; 75.9% female) demonstrated incidental FMD. The renal donor cohort included 220 patients (mean age 40.5 years; 64.5% female). Five (2.3%) demonstrated FMD (mean age 48.6 years; all female). The odds of FMD in the CORAL cohort were 2.65 times that seen in the renal donor cohort (95% CI: 1.12, 7.57). In conclusion, the 5.8% prevalence of renal artery FMD in the CORAL trial population, the presence of which was biased against, suggests underdiagnosis.

Treatment of Renal Artery Fibromuscular Dysplasia

Fibromuscular dysplasia is a nonatherosclerotic and noninflammatory disease that can result in stenoses of the renal arteries and hypertension, most commonly affecting middle-aged women. Percutaneous transluminal angioplasty has long been considered the mainstay of therapy and offers high rates of improved or cured hypertension. The disease involves the mid and distal renal arteries and branchpoints and poses endovascular treatment challenges that separate fibromuscular dysplasia from atherosclerotic disease. The development of smaller balloon dilation systems offers safe and highly effective endovascular treatment options for technically difficult lesions. Newer technologies such as cutting balloons also add to the armamentarium of treatment choices, which may be useful in the setting of resistant stenoses. This article focuses on the modern technical considerations in the diagnostic evaluation and endovascular treatment of renal artery fibromuscular dysplasia.

Thyroid Radiofrequency Ablation: Updates on Innovative Devices and Techniques

Radiofrequency ablation (RFA) is a well-known, effective, and safe method for treating benign thyroid nodules and recurrent thyroid cancers. Thyroid-dedicated devices and basic techniques for thyroid RFA were introduced by the Korean Society of Thyroid Radiology (KSThR) in 2012. Thyroid RFA has now been adopted worldwide, with subsequent advances in devices and techniques. To optimize the treatment efficacy and patient safety, understanding the basic and advanced RFA techniques and selecting the optimal treatment strategy are critical. The goal of this review is to therefore provide updates and analysis of current devices and advanced techniques for RFA treatment of benign thyroid nodules and recurrent thyroid cancers.

Characterizing Cardiopulmonary Arrest during Interventional Radiology Procedures

PURPOSE Careful case selection and preparation can prevent most cardiopulmonary arrest (CPA) in the interventional radiology (IR) suite. A series of CPAs was analyzed to provide insight into risk factors for these events. MATERIALS AND METHODS A single-institution CPA database was used to identify all code team activations from January 1, 2005, to May 30, 2011, in the IR department. Medical records were searched for medical history, American Society of Anesthesiologists (ASA) classification, moderate sedation, and outcomes. Procedural data and procedure classification was acquired from the HI-IQ database. RESULTS There were 36,489 procedures and 23 CPAs during the study period. Of the 23 patients with CPAs, 12 (52%) were male and 11 (48%) female, and average age was 57 years ± 19 (standard deviation). Risk factors included a 56% incidence of diabetes mellitus, 48% incidence of hypertension, and 78% incidence of renal failure. Of the patients with kidney disease, 56% were chronically dialysis-dependent, and an additional 9% were undergoing central venous catheter placement for new hemodialysis. Seventy-eight percent had ASA status of III or greater, and 57% underwent moderate sedation during the procedure. Relative risk of a CPA during dialysis shunt interventions versus arterial interventions was 3.6 (95% confidence interval, 1.0-11.3; P = .045). Eight of 23 (35%) died: one (12%) during resuscitation and seven (88%) after resuscitation (P = .070). CONCLUSIONS The most common comorbidity of patients with CPA in IR was kidney disease, and the most patients who had CPA underwent dialysis access-related procedures.

Percutaneous occlusion of the left subclavian and celiac arteries before or during endograft repair of thoracic and thoracoabdominal aortic aneurysms with detachable nitinol vascular plugs.

PURPOSE To review an experience with the Amplatzer vascular plug (AVP) for prevention of type II endoleaks during endovascular aneurysm repair (EVAR) of thoracic and thoracoabdominal aneurysms. MATERIALS AND METHODS Retrospective review was undertaken of 14 patients undergoing transcatheter occlusion of the left subclavian (n = 12) or celiac artery (n = 2) with the AVP as part of EVAR of thoracic and thoracoabdominal aneurysms at a single institution. Procedural criteria evaluated were success at target vessel occlusion, the number of AVPs used, use of adjunctive embolization devices, and embolization-related ischemic end-organ events. Follow-up imaging criteria included evaluation of persistent target vessel occlusion, evidence of device migration, and the presence and characterization of endoleak secondary to AVP failure. RESULTS Complete target vessel occlusion was documented for all cases. In six cases, more than one AVP was placed, with an average of 1.5 devices per patient. In two cases, adjunctive coils were placed. Computed tomographic or magnetic resonance angiography follow-up was available for all patients (mean follow-up, 419 days; range 28-930 d). No case showed evidence of device migration or type II endoleak resulting from AVP failure. There was a single instance of left subclavian artery recanalization without type II endoleak. There were no embolization-related ischemic end-organ events. CONCLUSIONS Transcatheter arterial occlusion of the subclavian and celiac arteries with the AVP is a valuable adjunct to endografting in cases in which side branch embolization is necessary to extend the landing zone.

Ten Frequently Asked Questions About MRI Evaluation of Soft-Tissue Vascular Anomalies

OBJECTIVE The objective of this article was to address 10 frequently asked questions that radiologists face when planning, performing, and interpreting an MRI study in a patient with a soft-tissue vascular anomaly. CONCLUSION MRI permits a comprehensive assessment of vascular anomalies. It is important for radiologists to be familiar with the classification and correct nomenclature of vascular anomalies as well as the MRI protocol and distinct imaging findings of the different vascular malformations and tumors.

Stenting for Atherosclerotic Renal Artery Stenosis

Atherosclerotic renal artery stenosis (ARAS) is the most common cause of renal artery stenosis in the adult population. ARAS may result in progressive renal impairment, renovascular hypertension, and/or cardiac disturbance syndromes. Because medical therapy does not affect the progressive nature of this disease process, more aggressive treatments are needed to definitively treat ARAS. When performed correctly, renal artery stenting has been shown to stabilize or improve renal function and/or renovascular hypertension in 65-70% of carefully selected patients with ARAS. Therefore, percutaneous renal artery stenting should be considered the primary treatment for patients with symptomatic ARAS.

Modified Balloon-Occluded Retrograde Transvenous Obliteration (BRTO) Techniques for the Treatment of Gastric Varices: Vascular Plug-Assisted Retrograde Transvenous Obliteration (PARTO)/Coil-Assisted Retrograde Transvenous Obliteration (CARTO)/Balloon-Occluded Antegrade Transvenous Obliteration (BATO)

Gastric varices in the setting of portal hypertension occur less frequently than esophageal varices but occur at lower portal pressures and are associated with more massive bleeding events and higher mortality rate. Balloon-occluded retrograde transvenous obliteration (BRTO) of gastric varices has been well documented as an effective therapy for portal hypertensive gastric varices. However, BRTO requires lengthy, higher-level post-procedural monitoring and can have complications related to balloon rupture and adverse effects of sclerosing agents. Several modified BRTO techniques have been developed including vascular plug-assisted retrograde transvenous obliteration, coil-assisted retrograde transvenous obliteration, and balloon-occluded antegrade transvenous obliteration. This article provides an overview of various modified BRTO techniques.