Elective embolization for prevention of hemorrhage from renal angiomyolipomas

Prophylactic Steroids for Preventing Postembolization Syndrome after Transcatheter Arterial Embolization of Renal Angiomyolipoma: A Comparative Study

Purpose

Postembolization syndrome (PES) after renal arterial embolization (RAE) can reduce the patient's tolerance of the procedure and extend the length of hospital stay. We aimed to assess the efficacy of steroid administration in preventing PES in patients undergoing RAE for angiomyolipoma (AML).

Material and Methods

Between May 2004 and March 2020, 29 RAE procedures in 26 patients with AML were performed. Patient information, including age, sex, tumor size, tuberous sclerosis complex-associated/sporadic AML, hemorrhagic/nonhemorrhagic AML, embolic material, steroid use, medication type, some blood laboratory parameters, hospital stay, and PES occurrence were retrospectively obtained. The prophylactic steroid protocol used in the study was as follows: 250 mg of intravenous methylprednisolone (Solu-Medrol) 2 h before the RAE procedure, followed by 2 days of intravenous prednisolone (Predonine; 2 mg/kg/day), which was tapered by halving the dose every 2 days within the course of 2 weeks. After the discharge, intravenous prednisolone was changed to oral prednisolone (Predonine). PES was defined as the presence of fever, pain, nausea, or vomiting. Data were compared between the steroid and non-steroid groups and between PES and non-PES groups.

Results

The PES incidence rate was 76%, and a comparison between the steroid and non-steroid groups revealed that steroid use significantly decreased the incidence of PES (P < 0.001), including fever (P < 0.001), pain (P = 0.005), and nausea (P = 0.028). The use of anti-inflammatory drugs during the hospital stay was significantly lower in the steroid group (P = 0.019). Moreover, in the steroid group, C-reactive protein level was significantly lower (P = 0.006), whereas white blood cell count was significantly higher (P = 0.004). Conversely, the median length of hospital stay was not significantly shorter in the steroid group (P = 0.292).

Conclusions

The prophylactic use of steroids before and after embolization of renal AML may be effective in preventing PES in this small retrospective study.

Efficacy and safety of selective renal arterial embolization in renal angiomyolipoma: a prospective single-center study

Background

Preventing acute complication of renal angiomyolipoma (AML), preserving renal parenchyma, and improving long-term renal function are the treatment targets of renal angiomyolipoma. Treatment should be considered for symptomatic lesions or those who are at risk of complications, especially bleeding symptoms, which are linked to tumor size, angiogenic component grade, and presence of tuberous sclerosis complex (TSC). Selective arterial embolization (SAE) has become the new norm for preventive or emergency treatment of renal AMLs with minimally invasive selective targeting of small arterial feeders, we aimed to assess the efficacy and safety of selective renal arterial embolization (SAE) in the management of complicated renal angiomyolipoma and to detect the predictors of prophylactic SAE in cases of non-complicated AML.

Results

Bleeding symptoms were significantly more frequent in patients with TSC-associated renal AMLs (C = 0.333 and p = 0.036) and patients with intra-lesional aneurysm > 3 mm (C = 0.387 and p = 0.013). Overall success rate: thirty-three (91.7%) renal AMLs were successfully embolized with no recurrence. While three (8.3%) renal AMLs were not; one (2.8%) renal AML was not embolized due to technical failure and two (5.5%) renal AMLs showed recurrence. Primary (technical) success rate: thirty-three (86.9%) successful embolization, five (13.1%) arteriographies were done with failed embolization. The maximum diameter and volume of the lesions after SAE showed statistically significant reduction (z = 4.25 and p < 0.001).

Conclusions

SAE is an effective and safe technique to manage renal AMLs preoperatively or in an emergency. TSC-associated lesions, and intra-lesional aneurysms (aneurysms > 3 mm in diameter) were significantly more associated with bleeding symptoms, considering them significant predictors for prophylactic SAE in non-complicated AML.

Different Treatments of Symptomatic Angiomyolipomas of the Kidney: Two Case Reports

Development of more sensitive imaging techniques has caused an increase in the number of diagnosed small renal tumors. Approximately 2-3% of these lesions are proved to be angiomyolipomas (AML), a rare benign tumor of the kidney sometimes causing pain and hematuria. The most required approach is observation, but in the case of recurrent symptoms or larger tumors, which may cause bleeding, a more active treatment is required. We present two cases of symptomatic AML tumors of different sizes in the kidney: one treated with transarterial embolization (TAE), and the other with percutaneous cryoablation (CRA). The lesions were diagnosed on the basis of contrast-enhanced computed tomography (CT) scan and magnetic resonance imaging (MRI). Both treatments proved to be effective and safe for treating renal AMLs. A follow-up carried out, based on contrast-enhanced CT scan, confirmed complete treatment of AML and decreased lesion size. There are myriad minimally invasive approaches for the treatment of renal AMLs, and the preservation of renal function remains a priority. The most popular treatment option is the selective renal artery embolization. Owing to its limited invasiveness, CRA could be an attractive option for the preventive treatment of AML.

Use of microspheres in embolization for unruptured renal angiomyolipomas

Purpose

To describe our initial experience with use of microspheres in transcatheter arterial embolization (TAE) for unruptured sporadic renal angiomyolipomas (AMLs).

Materials and methods

Seven consecutive patients with seven unruptured sporadic renal AMLs, 6 females and 1 male, with a median age of 45 years (range, 30–69 years), underwent TAE using microspheres between November 2016 and February 2020. We evaluated the technical success rate, complications related to the procedure, clinical success rate, and the shrinkage rate of renal AML. Technical success was defined as the completion of TAE. Clinical success was defined as presence of shrinkage of the renal AML after TAE.

Results

In all patients, TAE using microspheres was accomplished and technical success rate was 100% (7/7). Three patients exhibited slight pain, but it improved with only observation, and the minor complication rate was 43% (3/7) and major complication rate was 0% (0/7). After the TAE, shrinkage of renal AML was confirmed in 6 of 7 patients, and clinical success rate was 86% (6/7). The median of shrinkage rate was 47% (range, 26–83%) with a median follow-up period of 19 months (range, 4–30 months).

Conclusion

TAE using microspheres appears to be effective and safe for unruptured sporadic renal AMLs.

Efficacy of prophylactic selective arterial embolization for renal angiomyolipomas: identifying predictors of 50% volume reduction

Background

Transcatheter arterial embolization (TAE) has been widely performed for renal angiomyolipomas (AMLs) as prophylaxis or emergency treatment. On the other hand, mammalian target of rapamycin (mTOR) inhibitors have recently been used for tuberous sclerosis (TSC)-related AMLs, and no comparison between the effectiveness of mTOR inhibitors versus prophylactic selective TAE has yet been performed.

Therefore, the purpose of this study was to evaluate the efficacy of TAE for AML tumor volume reduction and predictors of tumor volume decrease over 50%, with reference to the EXIST-2 trial.

Methods

A total of 44 patients who underwent 48 prophylactic embolization procedures for 50 AMLs in a single institution between 2004 and 2018 were included. Indications for TAE of AMLs were tumor size ≥4 cm or aneurysm ≥5 mm in diameter on contrast-enhanced computed tomography (CECT). Microspheres, ethanol, and micro-coils were used as embolic agents. The percentage volume reduction from before TAE to the minimum volume during follow-up after TAE was calculated, and predictors for 50% volume reduction were identified by univariate and multivariate binary logistic regression analyses.

Results

The technical success rate was 100% (50 of 50). No severe acute complications related to the procedure were encountered. Tumor volume reduction of ≥50% was observed in 35/50 AMLs. There was a significant difference in the rate of tumor volume reduction of 50% between the presence and absence of an aneurysm ≥5 mm and between tumor diameter ≥ 70 mm and < 70 mm on univariate analysis. On multivariate analysis, tumor diameter < 70 mm was the only independent predictor of significant tumor volume reduction after TAE.

Conclusion

Prophylactic selective TAE for AMLs has good tumor-reduction effects, especially for AMLs with tumor diameter < 70 mm.

Clinical applications of digital angiography with the harmonization function in body interventional radiology

Digital subtraction angiography (DSA) is frequently applied in interventional radiology (IR). When DSA is not useful due to misregistration, digital angiography (DA) as an alternative option is used. In DA, the harmonization function (HF) works in real time by harmonizing the distribution of gray steps or reducing the dynamic range; thus, it can compress image gradations, decrease image contrast, and suppress halation artifacts. DA with HF as a good alternative to DSA is clinically advantageous in body IR for generating DSA-like images and simultaneously reducing various motion artifacts and misregistrations caused by patient body motion, poor breath-holding, bowel and ureter peristalsis, and cardiac pulsation as well as halation artifacts often stemming from the lung field. Free-breath DA with HF can improve body IR workflow and decrease the procedure time by reducing the risk of catheter dislocation and using background structures as anatomical landmarks, demonstrating reduced radiation exposure relative to DSA. Thus, HF should be more widely and effectively utilized for appropriate purposes in body IR. This article illustrates the basic facts and principles of HF in DA, and demonstrates clinical advantages and limitations of this function in body IR.

Renal angiomyolipoma-patient characteristics and treatment with focus on active surveillance

Objectives: To present a patient material of renal angiomyolipoma (AML) with focus on the risk of bleeding during active surveillance (AS).Methods: Medical records, 1999-2014, were studied and 98 patients (80 female, 18 men) with renal AML were identified. Eleven patients had tuberous sclerosis complex (TSC). Mean age was 54 (13-89) years.Results: Sixty patients (61%) were asymptomatic at presentation, 33 (34%) presented with flank pain and five (5%) with hematuria. Retroperitoneal bleeding or hematuria was diagnosed in 20 patients with a mean AML size of 74 mm (25-200 mm). Twenty-one patients were treated with angioembolization at time of diagnosis and 25 had surgery. Forty-five patients with sporadic AML (mean size 34 mm) and six with TSC (mean size 120 mm) were selected for AS. Only one patient with sporadic AML (46 mm) had a bleeding, whereas two of the six TSC patients had bleedings from three kidneys (AML 70-300 mm). In 25 patients (49%), the AML-size increased with 2.7 mm/year in sporadic and 5.4 mm/year in TSC-associated AML. Thirteen patients were treated with AE (including all six TSC-patients) and five with surgery in 22 kidneys due to AML-size in 16, bleeding in four and suspicion of cancer in two.Conclusion: Bleeding occurred in 20% of AML at presentation. In patients selected for AS, we found a very low risk of bleeding in sporadic AML justifying our cut off size of 50 mm to trigger intervention. In TSC-associated AML individually tailored follow-up is needed due to a higher intervention rate.

Selective Arterial Embolization for Large or Symptomatic Renal Angiomyolipoma: 10 Years of Follow-up

OBJECTIVE

To assess long-term outcome after selective arterial embolization (SAE) as first-line treatment for large or symptomatic AML.

DESIGN, SETTING, AND PARTICIPANTS

Data from a prospectively maintained database on 71 patients who underwent SAE for large or symptomatic AML were reviewed. Patients with sporadic and tuberous-sclerosis-complex (TSC) were included.

OUTCOME MEASUREMENTS

The main endpoints were re-embolization rates, occurrence of clinical events related to AML, size of AML, and renal function.

RESULTS

Thirteen (19.1%) patients reported at least 1 major clinical event. Major complications affected 2 patients (2.9%), both ending in complete loss of renal unit function. Four renal units (5.9%) were eventually treated surgically. The re-embolization rate was 41.1%, with an average time from the initial to a repeat SAE of 2.18 years (range 0.31-10.65 years). The size of the tumor prior to SAE and after 5 and 10 years of follow-up were 8.9 cm (7-12), 6.5 cm (4-7.5), 7 cm (4-7.8), respectively [median (IQR)]. These results are translated to a size reduction of 27% in 10 years follow-up. Patients with TSC had larger tumors on long-term follow-up (77.8 vs 41.3 mm, P = .045). The long-term follow-up estimated average glomerular filtration rate was 81.97 (range 26-196). No patient needed renal replacement therapy, and disease-specific survival was 100%.

CONCLUSIONS

SAE is a safe treatment option for patients with symptomatic or large AML. It represents a minimally invasive intervention with good long-term outcome. SAE may be offered as first-line treatment in most cases, though, it is associated with high retreatment rates.

Renal function, complications, and outcomes of a reduction in tumor size after transarterial embolization for renal angiomyolipomas: a meta-analysis

OBJECTIVE

The present study aimed to evaluate renal function, complications, and changes in tumor size after transarterial embolization for patients with renal angiomyolipomas.

METHODS

We performed a meta-analysis of transarterial embolization in patients with renal angiomyolipomas from January 1994 to April 2018. Endpoints of interest were the estimated glomerular filtration rate, serum creatinine levels, blood urea nitrogen levels, complications, and reduction of tumors.

RESULTS

A total of 30 studies comprising 653 patients were included. A total of 32.0% of patients were treated by urgent transarterial embolization for spontaneous ruptured renal angiomyolipomas. Other patients sought to relieve symptoms or received embolism prophylactically. The estimated glomerular filtration rate showed no significant difference between before and after embolization. In 363 patients with data on complications, post-embolization syndrome occurred most frequently (54.0%). Only 16 (4.4%) patients had major complications. The diameter of sporadic angiomyolipomas was reduced by a mean of 2.09 cm (95% confidence interval [CI], 0.73-3.45 cm; I2 = 29.3%) and they were reduced in size by 30.0% (95% CI, 16.0%-44.0%; I2 = 27.9%).

CONCLUSIONS

Transarterial embolization of renal angiomyolipomas affects renal function preservation, with a low complication rate. Transarterial embolization is useful for sporadic and tuberous sclerosis complex-related angiomyolipomas.

Evidence for a role of geranylgeranylation in renal angiomyolipoma and renal epithelioid angiomyolipoma

Research on mevalonate kinase deficiency has revealed that it may lead to the development of renal angiomyolipomas (RAMLs). Thus, it was suspected that geranylgeranyl pyrophosphate synthase (GGPPS), a key enzyme in the mevalonate pathway, may be involved in the development of RAMLs. In the present study, the expression of GGPPS in RAMLs and renal epithelioid angiomyolipomas (REAs) was assessed, and paraffin embedded specimens from 60 patients, including 9 cases with REA and 51 cases with RAML, were examined. Immunoreactivity was evaluated semi-quantitatively according to the intensity of staining and the percentage of positively stained cells. The results indicated that GGPPS was predominantly present in the cytoplasm, and REA tissues exhibited higher expression of GGPPS in the cytoplasm compared with RAML tissues. It was also identified that GGPPS was upregulated in TSC2-null cells, and inhibition of GGPPS could induce apoptosis of TSC2-null cells by autophagy. In conclusion, the increased expression of GGPPS in RAMLs and REAs indicated that mevalonate pathways may be involved in disease progression. GGPPS may serve as a potential therapeutic target and the current results may provide a novel therapeutic strategy for RAML and lymphangioleiomyomatosis.

Are We Overtreating Renal Angiomyolipoma: A Review of the Literature and Assessment of Contemporary Management and Follow-Up Strategies

Renal angiomyolipoma (AML) are benign tumours composed of fat, muscle, and disorganised blood vessels. Historic treatment algorithms for sporadic AML based on size fail to consider additional risk factors such as tumour vascularity and pseudoaneurysm formation. As AML is now predominantly incidental, rupture is rare and its mortality low. The recent publication of the largest longitudinal series to date also suggest that growth is uncommon, challenging existing surveillance paradigms. The evidence assessing treatment strategies in AML are reviewed, with particular emphasis on incidental sporadic AML. The relative merits of various AML treatments are discussed, and areas of clinical uncertainty highlighted.

Can "Tumor-to-Cortex Echogenicity Ratio" Differentiate Angiomyolipomas from Other Hyper-Echoic Renal Masses

A retrospective study was performed to evaluate the diagnostic value of tumor-to-cortex echogenicity ratio (TCER) in the characterization of hyper-echoic renal masses. The radiology database was queried between 2012 and 2014 for hyper-echoic renal masses on the basis of defined exclusion and inclusion criteria. Each included mass was characterized as either an angiomyolipoma (AML) or a non-AML based on pre-defined criteria. The ratio of renal mass echogenicity to that of adjacent renal cortex (TCER) was calculated for each mass using commercially available software. A total of 70 masses in 65 patients were identified, including 49 AMLs. TCER values >2.26 were associated with a sensitivity and specificity of 81.6% and 71.4%, respectively, for diagnosis of AML. Moreover, TCER values >3.98 resulted in 100% specificity for AML diagnosis with a sensitivity of 28.6%. These findings suggest that the TCER may be a valuable tool for the characterization of hyper-echoic renal masses.

Selective arterial embolization of symptomatic and asymptomatic renal angiomyolipomas: a retrospective study of safety, outcomes and tumor size reduction

BACKGROUND

Angiomyolipoma (AML) is the most common renal benign tumor. Treatment should be considered for symptomatic patients or for those at risk for complications, especially retroperitoneal bleeding which is correlated to tumor size, grade of the angiogenic component and to the presence of tuberous sclerosis complex (TSC). This study reports our single-center experience with the use of selective arterial embolization (SAE) in the management of symptomatic and asymptomatic renal AMLs.

METHODS

In this retrospective mono-centric study, all demographic and imaging data, medical records, angiographic features, outpatient charts and follow-up visits of patients who underwent prophylactic or emergency SAE for AMLs between January 2005 and July 2016 were reviewed. Tumor size and treatment outcomes were assessed at baseline and after the procedure during follow-up. Computed tomography (CT), magnetic resonance imaging (MRI) or ultrasonography was used to evaluate AML shrinkage. Renal function was measured pre- and post-procedure.

RESULTS

Twenty-three patients (18 females, 5 males; median age, 45 years; range, 19-85 years) who underwent SAE either to treat bleeding AML (n=6) or as a prophylactic treatment (n=17) were included. Overall, 34 AMLs were embolized. TSC status was confirmed for 6 patients. Immediate technical success rate was 96% and 4 patients benefitted from an additional procedure. Major complications occurred in 3 patients and minor post-embolization syndrome (PES) in 14 patients. The mean AML size reduction rate was 26.2% after a mean follow-up was 20.5 months (range, 0.5-56 months), and only non-TSC status was significantly associated with better shrinkage of tumor (P=0.022). Intralesional aneurysms were significantly more frequent in patients with hemorrhagic presentation (P=0.008). There was no change in mean creatinine level after SAE.

CONCLUSIONS

SAE is a safe and effective technique to manage renal AMLs as a preventive treatment as well as in emergency setting, with significant reduction in tumor size during follow-up. A multidisciplinary approach remains fundamental, especially for TSC patients. In addition to size, the presence of intralesional aneurysms should be considered in any prophylactic treatment decision.

Urgent transcatheter arterial embolization for the treatment of ruptured renal angiomyolipoma with spontaneous hemorrhage

Background The rich neovascularization of renal angiomyolipoma (AML) has a tendency for spontaneous rupture with subsequent hemorrhage. Nephrectomy or nephron-sparing surgery has rarely been used as a primary treatment in urgent situations. Purpose To evaluate the safety and long-term outcomes for patients treated by urgent transcatheter arterial embolization (TAE) for spontaneous ruptured renal AML with severe hemorrhage. Material and Methods A retrospective evaluation was performed of 25 renal AML cases with spontaneous hemorrhage confirmed by imaging. Polyvinyl alcohol (PVA) particles and coils of multiple sizes were used to embolize the spontaneous renal AML ruptures. Results The technical success rate of TAE was 96% (24/25). One week post-TAE, 1 patient with recurrent hemorrhage underwent emergency nephrectomy. Minor complications affected 16 patients with post-embolization syndrome; 15 patients resolved using conservative measures and one patient received nephrectomy post TAE 1 week later. All patients were followed up for 24-72 months (median, 50.2 months). Surgical treatment was avoided for 92% (23/25) of patients, and the re-embolization rate was 0% at 2 years post TAE. In the 23 patients without surgical treatment, the mean maximum diameter of renal AML was reduced from 12.4 ± 5.5 cm to 6.3 ± 2.5 cm and no hemorrhage occurred during follow-up. Conclusion Urgent TAE is a technically feasible and minimally invasive procedure for controlling severe hemorrhage and preservation of renal function following spontaneous ruptured renal AML.

Differentiation of Sporadic Versus Tuberous Sclerosis Complex-Associated Angiomyolipoma

OBJECTIVE

We review the imaging of renal angiomyolipomas, including differentiation of tuberous sclerosis complex (TSC)-associated and sporadic renal angiomyolipomas and other solid renal tumors. We also focus on radiologic interventions and molecular targeting of the TSC genetic pathway.

CONCLUSION

Imaging plays a central role in the diagnosis and management of renal angiomyolipomas. It provides essential information to make the best therapeutic decisions about the interventional and pharmacologic options to help prevent bleeding and preserve functional parenchyma.

Acute Urinary Tract Disorders

Acute urinary tract disorders often manifest as flank pain and are a common complaint of patients who present to the emergency department. The pain is often a vague, poorly localized sensation that may have a variety of causes. Laboratory and clinical findings, such as hematuria, are neither sensitive nor specific for determining the cause of the flank pain. Accordingly, imaging is an important tool in determining a diagnosis and management plan. Patients with acute urinary tract disorders who present with pain include those with calculi as well as renal infection, vascular disorders, and hemorrhage.

Endovascular intervention in renovascular disease: a pictorial review

Interventional radiologic procedures offer a significant and expanding role in the management of various renovascular diseases including renal artery stenosis, renal artery aneurysm and pseudoaneurysm, renal vascular malformations, renal tumours, trauma, and resistant hypertension. In this article, we discuss these entities in the context of currently accepted definitions, incidence, modes of diagnosis, and management as they pertain to the practice of interventional radiology. Particular emphasis is placed on current interventional procedures for managing and treating these diseases as well as emerging procedures and technologies.

• Highlights the literature on renovascular diseases

• Reviewing the role of various interventional procedures in the management of renovascular disease

• Review of imaging techniques in the identification and characterisation of renovascular disease

Role of embolization in the treatment of renal masses

Renal arterial embolization (RAE) performed for the treatment of renal masses has been proven to be a safe and effective technique, with several decades of experience. RAE is well tolerated with few complications, particularly if the time interval from embolization to surgery is reduced to less than 48 hours. Review of the literature suggests that RAE is also extremely effective for palliation of symptoms in the setting of nonoperative advanced stage renal cell carcinoma. In addition, this technique plays a large role in the management of angiomyolipomas that are symptomatic or at risk of spontaneous rupture. To date, RAE has not been evaluated in a randomized controlled setting, which has contributed to its underutilization. All of these potential benefits warrant the need for prospective studies for further validation.

Patterns of renal angiomyolipoma regression post embolisation on medium- to long-term follow-up

OBJECTIVE

To assess the patterns of regression of renal angiomyolipoma (AML) post embolisation and report the outcomes related to the use of different embolic materials.

METHODS

A retrospective review of all patients who underwent embolisation for renal AML at our institution between January 2004 and April 2012.

RESULTS

13 patients underwent 16 episodes of embolisation. Coils were used as the primary embolisation material in 10 episodes and microspheres in 6 episodes. The size reduction rate highly correlated on CT follow-up between the two groups, with 25.6% vs 22.7% reduction at 12 months, 27.5% vs 25.1% at 24 months, 35.0% vs 33.0% at 36 months and 35.0% vs 36.8% at 48 months. During follow-up, all tumours reduced in size with one patient requiring subsequent embolisation whose tumour reduced by only 6.5% after 1 year and subsequently exhibited regrowth after 4 years. Two patients presented with rebleeding and underwent repeat embolisation. Our overall retreatment rate (23%) is well within the literature range (up to 37%). None of the patients underwent surgery.

CONCLUSION

The majority of AML shrinkage occurs within the first year following embolisation and appears to plateau after 3 years, which could have an impact on follow-up strategy. The percentage reduction at 1 year may reflect the long-term effect of embolisation with tumours demonstrating minor size reduction more likely to relapse at long-term follow-up. Embolisation of renal AML produces durable long-term results regardless of the choice of embolic agent.

ADVANCES IN KNOWLEDGE

These findings provide information to guide CT follow-up of renal AML post embolisation.

Renal angiomyolipomas in tuberous sclerosis--rare but potentially life-threatening lesions

We discuss an 18-year-old girl, diagnosed with tuberous sclerosis complex and known to have renal angiomyolipomas (AMLs) but having no regular urological follow-up, who presented with left-sided abdominal pain and haematuria on urine dipstick testing at the out-of-hours General Practitioner (GP) service. She was diagnosed as having urinary tract infection/pyelonephritis and discharged with simple analgesia and antibiotics. Subsequent imaging of her renal tract demonstrated multiple large AMLs with evidence of recent bleeding, which required arterial embolisation.

Renal artery embolization

Renal artery embolization (RAE) is an effective minimally invasive alternative procedure for the treatment of a variety of conditions. Since the 1970s when RAE was first developed, technical advances and growing experience have expanded the indications to not only include treatment of conditions such as symptomatic hematuria and palliation for metastatic renal cancer, but also preoperative infarction of renal tumors, treatment of angiomyolipomas, vascular malformations, medical renal disease, and complications following renal transplantation. With the drastically improved morbidity associated with this technique in part due to the introduction of more precise embolic agents and smaller delivery catheters, RAE continues to gain popularity for various urologic conditions. The indications and techniques for renal artery embolization are reviewed in the following sections.

[Guidelines for the management of tuberous sclerosis complex renal disease]

PURPOSE

To review existing literature and deduce guidelines for the management of renal disease in patients with tuberous sclerosis complex (TSC).

PATIENTS

After review of literature, a core panel of five physicians wrote a draft that was evaluated by 14 reviewers who used a 9-level scale (1: total disagreement; 9: total agreement). The guidelines were then reformulated until each item received a median score superior or equal to 8.

RESULTS

Forty-eight to 80 % of TSC patients have significant renal involvement including angiomyolipomas (AMLs), cysts, malignant tumors and renal insufficiency. It is recommended to perform an abdominal ultrasound (and serum creatinine if abnormal ultrasound) when TSC is diagnosed. This work-up will be repeated every 3-5years if normal. Associated autosomal dominant polycystic kidney disease must be suspected in case of numerous and large cysts. After the age of 20, follow-up should use computed tomography (CT) or MRI that are more precise than ultrasound for the measurement of AMLs. Biopsy of a renal mass should be discussed in case of calcifications, necrosis or rapid growth. Females with TSC should undergo screening for pulmonary lymphangioleiomyomatosis by CT at the age of 18, and, if negative at the age of 30-40. Acute bleeding should be treated with percutaneous embolization. Asymptomatic angiomyolipomas with several risk factors (size>80mm, predominant vascular component, micro-aneurysms) should undergo prophylactic treatment, if possible using embolization. The role of mTOR inhibitors in the management of angiomyolipomas needs to be defined.

CONCLUSION

Standardization of follow-up and treatment is necessary to improve the management of TSC renal involvement.

Pharmaceuticals for Intra-arterial Therapy

Clinical pharmacology may be defined as the branch of medicine concerned with the therapeutic agents used in the prevention, treatment, and control of disease. Pharmaceuticals are the specific agents used to combat disease. Hence, many of the agents used by the interventionalist may be considered pharmaceuticals. Safe and effective use of these therapeutics requires understanding of vascular anatomy and disease pathology, proper technique, and knowledge of the therapeutic agents. This article reviews many of the agents available and some that are on the horizon. The future of transarterial therapies is bright and holds many promises.

Prophylactic embolization of renal angiomyolipomas: evaluation of therapeutic response using CT 3D volume calculation and density histograms

PURPOSE

To evaluate the efficacy and tolerance of prophylactic embolization of angiomyolipomas (AMLs) and to analyze the therapeutic response by using three-dimensional 3D volume calculation and 3D quantification of fatty and angiomyogenic components during computed tomography (CT) follow-up.

MATERIALS AND METHODS

Over a 51-month period, 30 patients with 34 AMLs (mean diameter, 82 mm ± 37; range, 30-173 mm) underwent 37 prophylactic embolization procedures. The protocol included supraselective arterial embolization with a combination of absolute alcohol, microparticles, and coils. Mean clinical and imaging follow-up were 20.5 and 14.5 months, respectively. The 3D volume calculation and density histograms were retrospectively analyzed for treatment evaluation.

RESULTS

Four technical failures were observed (11%), with one successful secondary reattempt, resulting in 31 AMLs (91.2%) being embolized. Thirty (88.2%) had CT follow-up and were included in the analysis. Embolization was complete after a single procedure for 25 AMLs (83%) and required two procedures in two cases. Three AMLs had incomplete embolization and were scheduled for a second procedure. Mean volume reductions were 43% ± 32 for AMLs followed for 1-6 months after embolization and 81% ± 19 for the 12 AMLs followed for more than 1 year. The volume reduction after embolization was significantly correlated with the AML initial composition, with fat-rich AMLs showing a much smaller reduction of size than predominantly angiomyomatous AMLs (P < .05).

CONCLUSIONS

Prophylactic embolization allows significant reduction of AML volume with a high success rate. Three-dimensional CT volume and density histogram calculations suggest that it is especially effective on angiomyogenic components and fat-poor AMLs.

Conservative management of a retroperitoneal hemorrhage following a ruptured renal angiomyolipoma in pregnancy

Retroperitoneal hemorrhage following ruptured renal angiomyolipoma is usually managed surgically or by embolization. But when the same episode occurs in pregnancy, surgery which predisposes to preterm delivery and its subsequent sequelae, the unknown influences of radiation exposure on the fetus makes the management of such cases very challenging. A 21-year-old woman was seen in the emergency unit at the 25th week of her pregnancy with complaints of sudden onset left flank pain radiating to the back, nausea and hematuria. Abdominal magnetic resonance imaging (MRI) revealed masses consistent with angiomyolipoma in the upper pole of the left kidney with evidence of recent bleeding and the center of the right kidney measuring 11.5 × 9.5 cm and 3.5 cm, respectively. The patient received three units of red blood cell concentrate due to fall in hematocrit level resulting in hemodynamically stable condition until term. At term, an infant weighing 3510 g was delivered through elective cesarean section. To avoid iatrogenic preterm delivery and unnecessary fetal exposure to radiation, conservative management of ruptured angiomyolipoma in pregnancy may be considered as a treatment option in hemodynamically stable patients.

The efficacy, safety and durability of selective renal arterial embolization in treating symptomatic and asymptomatic renal angiomyolipoma

OBJECTIVE

To review the long-term outcome of selective renal arterial embolization (SAE) in treating renal angiomyolipomas (AMLs) in both elective and emergency settings.

MATERIALS AND METHODS

Between October 1988 and September 2008, 27 patients (28 renal units) were treated with SAE, either on an emergency basis for 15 (53.6%) bleeding AMLs or prophylactically for 13 (46.4%) asymptomatic high-risk (size >4.1 cm) AMLs. Six males and 21 females with a mean age of 46.3 years (range, 26-68) were followed for a mean period of 7.1 years (range, 1.3-20.2) for recurrence of symptoms, need for re-embolization, or need for renal surgery. SAE outcome was evaluated using the Kaplan-Meier method. Predictor(s) of outcome were identified with univariate analysis by log-rank test.

RESULTS

Mean size of AMLs was 10.9 cm (range, 4-30). Eight (29.6%) patients had bilateral and 19 (70.4%) had unilateral AMLs. Seventeen (60.7%) kidneys had solitary AMLs; 11 (39.2%) kidneys had multicentric AMLs. Of the 15 bleeding AMLs, 12 (80%) patients required a blood transfusion. Twenty-six (93%) AMLs were successfully embolized in the first SAE. During follow-up, four (14.8%) patients required re-embolization. Renal surgery was required in four (14.8%) patients. From the Kaplan-Meier analysis, the overall renal surgery sparing rate at 5 years was 85% (95% CI: 71-99%), whereas the single session SAE success rate at 5 years was 63% (95% CI: 42-84%). Of all the variables, only AML >10 cm was significantly associated with the subsequent need for renal surgery (P = .03). No renal malignancy was noted at final follow-up.

CONCLUSIONS

SAE is effective and durable in preventing large AMLs from bleeding, treating AMLs presenting with bleeding, and sparing the need for renal surgery.

Transcatheter arterial embolization in patients with kidney diseases: an overview of the technical aspects and clinical indications

Therapeutic embolization is defined as the voluntary occlusion of one or several vessels, and this is achieved by inserting material into the lumen to obtain transient or permanent thrombosis in the downstream vascular bed. There are a number of indications for this approach in urological practice, in particular for the patients with parenchymatous or vascular kidney disease. In this review, we present the different embolization techniques and the principally employed occluding agents, and then we present the principal clinical indications and we discuss other pathologies that may benefit from this non-invasive therapy. The complications, side effects and main precautions associated with this approach are also described.

Embolization of giant renal angiomyolipomas: technique and results

PURPOSE

To evaluate the efficacy and safety of prophylactic embolization of angiomyolipomas (AMLs) larger than 10 cm.

MATERIALS AND METHODS

Sixteen patients (mean age, 41.2 years; 14 women and two men) underwent embolization for 23 AMLs larger than 10 cm. All lesions were embolized by using microcatheters with ethanol and ethiodized oil mixed to a ratio of 7(ethanol) to 3(ethiodized oil). Data collected included pre- and posttreatment AML size, creatinine level, technical success, volume of embolic material used, clinical success, and complications.

RESULTS

The mean AML size before treatment was 15 cm (range, 10-25 cm). Ten of the 16 patients (62%) had all their AMLs treated in one session, whereas six (38%) required multiple sessions. A mean volume of 8.6 mL of the ethanol-ethiodized oil mixture (range, 2-20 mL) was administered per lesion. Patients were followed up for a mean of 29 months (range, 1-80 months). No patient had an increase of 0.2 mg/dL (17.7 mumol/L) or greater in mean serum creatinine level during the follow-up period. Two of the 16 patients (12%) required repeat embolization due to AML regrowth (n = 1) or reperfusion (n = 1) seen at surveillance imaging. One of the 16 patients (6.2%) had an AML hemorrhage 59 months after AML embolization.

CONCLUSIONS

Embolization of giant renal AMLs to decrease the risk of bleeding can be done safely without loss of renal function. Although recurrence was infrequent, additional treatment may be necessary and giant renal AMLs should be followed up with serial imaging studies.

Transcatheter renal artery embolization: clinical applications and techniques

Renal artery embolization is a minimally invasive procedure that is increasingly being used for treatment of a wide range of conditions. The main indications for renal artery embolization include (1) prenephrectomy and preradiofrequency ablation infarction of renal tumors, (2) management of renal angiomyolipomas, (3) palliations of unresectable renal malignancy, (4) renal hemorrhage (life-threatening or chronic debilitating hematuria), (5) arteriovenous fistulas, (6) vascular malformations, (7) renal artery aneurysms and pseudoaneurysms, and other less common indications, such as severe hydronephrosis and hypertension. A variety of embolic materials are available, such as metal coils, sclerosants (glue, Onyx, absolute ethanol, lipiodol), and particulate embolic agents (polyvinyl alcohol particles and embospheres). Selection of the appropriate agent depends on the clinical application, technical and clinical endpoints, as well as the pathology lesion(s) targeted. Renal artery embolization can be performed alone or in combination with remodeling techniques, stent-grafting, and balloon- or stent-assisted coiling in more complicated cases. The procedure is generally regarded as safe and effective for diverse applications and is considered as an evolving area in the field of endoluminal therapy.

Endovascular therapy for patients with renal angiomyolipoma presenting with retroperitoneal haemorrhage

We report our experience treating four patients with acutely bleeding angiomyolipoma (AML) of sizes between 4 and 12 cm who were managed with endovascular embolisation with a mean follow-up of 10 months. In our case series, we demonstrate that endovascular embolisation in the acute setting for bleeding AMLs is a viable treatment option. AML should be in the differential diagnosis of acutely bleeding renal masses, even when there is no fat assessed by computed tomography (CT) imaging in the renal mass.

A case of lipiduria after arterial embolization for renal angiomyolipomas

We report the case of a 31-year-old woman who suffered lipiduria after selective transcatheter arterial embolization for renal angiomyolipoma (AML). Computed tomography confirmed cystic liquefactive necrosis with fat-fluid level in AML. Although the process by which AML fat tissue excretion occurs is not clear, we speculated that the infarcted AML was connected to the urinary collection duct system and subsequently its adipose component was excreted into the urine.

The radiological diagnosis and treatment of renal angiomyolipoma-current status

Angiomyolipomas (AMLs) are the most common benign renal neoplasm and are often discovered incidentally. Due to both an increase in the use of imaging, as well as advances in imaging technology, they are being increasing identified in the general population. As these lesions are benign, there is good evidence that the majority of them can be safely followed up without treatment. However, there is an increasing wealth of information available suggesting there are individuals with AMLs where prophylactic treatment is indicated to prevent complications such as haemorrhage. In such cases, treatment with radiological interventional techniques with subselective particle embolization has superseded surgical techniques in most cases. Even in emergency cases with catastrophic rupture, prompt embolization may save the patient with the additional benefit of renal salvage. Confident identification of a lesion as an AML is important as its benign nature obviates the need for surgery in most cases. The presence of fat is paramount in the confirmatory identification and characterization of these lesions. Although fat-rich AMLs are easy to diagnose, some lesions are fat poor and it is these cases where newer imaging techniques, such as in-phase and out-of-phase magnetic resonance imaging (MRI) may aid in making a confident diagnosis of AML. In this paper, we comprehensively review the imaging techniques in making a diagnosis of AML, including features of both characteristic lesions as well as atypical lesions. In addition, we discuss current guidelines for follow-up and prophylactic treatment of these lesions, as well as the increasing role that the interventional radiologist has to play in these cases.

[Role of percutaneous arterial embolization in renal pathology]

Therapeutic embolization in renal pathology is used for various conditions in cancerology, traumatology, urology, nephrology and for iatrogenic complications of percutaneous manoeuvers. Any department of vascular radiology may be requested to use this technique, especially in emergent traumatology or palliative cancerology. The authors study the various conditions that may benefit from these procedures and give the highlights of the main indications and the main types of embolic agents used. Complications, side effects and the major precautions are also reviewed.

Long-term follow-up of the treatment of renal angiomyolipomas after selective arterial embolization with alcohol

STUDY TYPE

Therapy (case series).

LEVEL OF EVIDENCE

4.

OBJECTIVE

To present our institution's experience of selective embolization of renal angiomyolipomas with alcohol and the long-term follow up data.

PATIENTS AND METHODS

This retrospective study included 34 patients treated between October 1997 and October 2007 (29 women and five men, mean age 44 years). Of these patients, nine had tuberous sclerosis, 14 were bilateral and 16 were multifocal. Indications for treatment were previous haemorrhage (14), size >4 cm (19) and increasing size over a short period (one). The largest treated lesion was 24.4 cm, and the mean (range) size was 11.9 (2.9-24.4) cm. All patients were treated by selective embolization using a mixture of alcohol and lipiodol. Three patients also had coiling of aneurysms and two patients had additional embolization with polyvinyl alcohol particles. The follow-up was both radiological and clinical, with recurrence defined as growth by >2 cm or symptoms requiring further treatment.

RESULTS

The technical success rate was 100%, with only one significant complication of non-target renal embolization, with self-limiting effects. Minor complications included 11 patients with post-embolization syndrome, all of which settled with conservative measures. The mean (range) combined radiological and clinical follow-up was 44.2 (12-116) months, with all patients having a follow-up of >1 year. Radiological success was achieved in 97%, with only one lesion growing by >2 cm. The combined clinical and radiological success rate was 85%, with two patients undergoing surgery, two having repeat embolization and one currently offered surgery due to a recent increase in size.

CONCLUSION

Our study provides long-term evidence that selective arterial embolization with alcohol is a safe and effective method for improving clinical symptoms (85%) and preventing tumour progression (97%) in patients with renal angiomyolipoma.

Pulmonary edema as a complication of transcatheter embolization of renal angiomyolipoma in a patient with pulmonary lymphangioleiomyomatosis due to tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal-dominant disorder characterized by seizures, mental retardation, and various hamartomatous lesions, including renal angiomyolipoma (AML) and pulmonary lymphangioleiomyomatosis. A 22-year-old woman with TSC presented with multiple renal AMLs exceeding 4 cm in diameter. She underwent two transcatheter embolization procedures with a mixture of ethanol and iodized oil. She complained of dyspnea and minor hemoptysis 4 and 6 hours after the procedure. Findings on chest radiographs and computed tomographic images were indicative of pulmonary edema. The patient was treated with conservative therapy. The possible causes of the pulmonary edema are discussed in the text.

Transcatheter embolisation of renal angiomyolipoma

INTRODUCTION

Angiomyolipomas (AML) are rare benign renal tumours which are associated with aneurysms that can cause haemorrhage. Embolisation of AML greater than 4 cm with a variety of embolic agents is now the first-line treatment in these cases.

METHODS

This was a retrospective analysis of all patients who underwent AML embolisation at Beaumont Hospital from 2000 to 2006 to review the efficacy of embolisation in the treatment of AMLs.

RESULTS

There were six patients in total (n = 6). One patient (16%) had a background of tuberous sclerosis. Half of the patients presented acutely with bleeding and abdominal pain (50%) while the other half were found incidentally. There were no mortalities overall and three patients (50%) developed post embolisation syndrome. Five patients (83%) had a good response to embolisation with no further growth or regression of the AML.

CONCLUSION

Embolisation is a safe and effective method for treating patients with AML.

Evaluation of renal function of angiomyolipoma patients after selective transcatheter arterial embolization

BACKGROUND

Angiomyolipoma patients may have renal insufficiency before selective transcatheter arterial embolization (TAE) or may undergo subsequent surgery after TAE. Therefore, this retrospective study examined our experience with TAE or TAE and subsequent surgery on renal function of angiomyolipoma patients with and without preexisting renal insufficiency.

METHODS

25 patients who had undergone TAE for renal angiomyolipoma over a 7-year period were reviewed. The 25 patients were grouped according to whether or not they had undergone further surgery. Preexisting renal insufficiency was compared between the 2 groups. The TAE and surgery group was further subdivided into 2 subgroups according to total nephrectomy or not. The TAE-alone group was further subdivided into 2 subgroups by presence of preexisting renal insufficiency or not. In each group and subgroup, pre-TAE and post-TAE renal function, including serum creatinine and creatinine clearance were compared.

RESULTS

TAE rather than TAE and surgery was more likely chosen in the presence of preexisting renal insufficiency (6/13 versus 1/12, P=0.035). In TAE-alone patients, no statistical differences were noted between serum creatinine and creatinine clearance before and after TAE. Conversely, TAE and surgery patients who had undergone total nephrectomy rather than nephron-sparing surgery differed significantly in preand post-TAE serum creatinine (0.77 versus 1.07, P=0.014) and creatinine clearance (98.1 versus 70.7, P=0.032).

CONCLUSIONS

This study demonstrated that TAE alone for treating renal angiomyolipomas was able to preserve renal function, despite the presence of mild preexisting renal insufficiency. Conversely, surgery after TAE, particularly total nephrectomy, should be avoided whenever possible.

Transarterial ethanol ablation for sporadic and non-hemorrhaging angiomyolipoma in the kidney

PURPOSE

We evaluated the efficacy and side effects of transarterial ethanol ablation in sporadic and non-hemorrhaging angiomyolipomas (AMLs) in the kidney.

MATERIAL AND METHODS

A total of 10 patients with solitary and sporadic AMLs underwent selective transarterial absolute ethanol ablation for prophylaxis against hemorrhage. We confirmed the ratio areas of tumor vessel on angiogram, those of infraction on post-ablation computed tomography (CT) and those of tumor reduction in a 3-, 6- and 12-month follow-up CT.

RESULTS

Once or twice a single infusion of 1 or 2 ml absolute ethanol achieved in a total occlusion of 22 feeding arteries which consisted of 7 proximal interlobar arteries, 12 distal interlobar arteries and 3 renal capsular arteries. Nontarget occlusion did not occur by ethanol reflux in any cases but occurred causing spasms provoked by repeated inflation and deflation of the balloon in one case. Total occlusion of tumor vessels was observed in 7 patients and 92-95% occlusion in 3. Ethanol ablation produced 1.8-22.5% (mean 8.4+/-6.8%) areas of infarctions but the outcome was not serious in all cases. Mean percentage areas of tumor reduction were 29.4+/-10.6% in a 3-month follow-up, 45.7+/-11.9% in a 6-month and 59.3+/-11.5% in a 12-month follow-up.

CONCLUSIONS

Absolute ethanol ablation for sporadic and non-hemorrhaging AML is safe and effective in reducing majority of tumor area in a 1-year follow-up.