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

Renal angiomyolipoma: Beyond size criteria for predicting rupture

INTRODUCTION

Renal angiomyolipomas (AMLs) are vascular tumours that while histologically benign, carry a risk of rupture and potentially life-threatening haemorrhage. Selective arterial embolisation (SAE) has been demonstrated as effective treatment; however, given most tumours are asymptomatic, the challenge facing the radiologist is selection of which AML should undergo treatment. This study considers presence and size of intratumoural aneurysm, to advance the readers treatment decision-making beyond historical size criteria.

METHODS

Retrospective cohort analysis of all SAE-treated AML at a quaternary-level institution in the last 10 years was completed independently by two radiologists. Computerised tomography (CT) and angiographic imaging were reviewed to evaluate tumour size, presence of intratumoural aneurysm and aneurysm size. Univariant and multivariant statistical analyses were used to identify predictors of spontaneous rupture and haemorrhage.

RESULTS

Twenty-seven renal AML underwent SAE. Five tumours had presented with haemorrhage. Twenty-two were asymptomatic or without CT/angiographic detectable haemorrhage. There was no statistically significant size difference between ruptured (mean 7.8 cm, range 6.1-12.0 cm) and unruptured AML (7.5 cm, 3.3-21.7 cm) in the study population. Eighty percent of ruptured AML and 27% of unruptured AML contained at least one intratumoural aneurysm (P-value < 0.05). Mean aneurysm size in ruptured AMLs was 5.4 mm, versus 4.6 mm among unruptured AML (P-value > 0.05).

CONCLUSION

The presence of intratumoural aneurysm is a useful predictor for AMLs that are at risk of spontaneous rupture and haemorrhage. Intratumoural aneurysm should therefore be considered when selecting patients to undergo SAE.

Serum lactate dehydrogenase concentration after transcatheter renal artery embolization correlates with reduction in renal angiomyolipoma volume

BACKGROUND

The extent of renal angiomyolipoma (AML) volume reduction after renal transcatheter arterial embolization (TAE) varies between patients, with no predictive measure available.

PURPOSE

To determine whether the serum lactate dehydrogenase (LDH) concentration shortly after TAE correlates with the extent of tumor shrinkage.

MATERIAL AND METHODS

In a cohort of 36 patients undergoing prophylactic renal TAE for unruptured renal AML, we retrospectively acquired data from patient medical records, including serum LDH before and within 7 days after TAE and the tumor volume before and 12-36 months after TAE. The relationship between the serum level of LDH and reduction in tumor volume was evaluated using Spearman correlation analysis.

RESULTS

The median LDH concentration was significantly higher after TAE than before (909.0 U/L vs. 186.5 U/L). This early post-TAE serum LDH level and LDH index (post-TAE LDH / pre-TAE LDH) correlated significantly and positively with the absolute decrease in tumor volume (both P < 0.0001). We observed no significant correlation between the relative tumor volume reduction and serum LDH level or LDH index.

CONCLUSION

Serum LDH elevation occurs shortly after TAE and correlates with the extent of absolute decrease in AML volume at 12-36 months after TAE. Further large-scale studies are warranted to confirm the predictive role of post-TAE serum LDH level and LDH index in tumor shrinkage in patients with unruptured renal AML.

Wunderlich Syndrome: Comprehensive Review of Diagnosis and Management

Wunderlich syndrome (WS), which was named after Carl Wunderlich, is a rare clinical syndrome characterized by an acute onset of spontaneous renal hemorrhage into the subcapsular, perirenal, and/or pararenal spaces, without a history of antecedent trauma. Patients may present with a multitude of symptoms ranging from nonspecific flank or abdominal pain to serious manifestations such as hypovolemic shock. The classic symptom complex of flank pain, a flank mass, and hypovolemic shock referred to as the Lenk triad is seen in a small subset of patients. Renal neoplasms such as angiomyolipomas and clear cell renal cell carcinomas that display an increased proclivity for hemorrhage and rupture contribute to approximately 60%-65% of all cases of WS. A plethora of renal vascular diseases (aneurysms or pseudoaneurysms, arteriovenous malformations or fistulae, renal vein thrombosis, and vasculitis syndromes) account for 20%-30% of cases of WS. Rare causes of WS include renal infections, cystic diseases, calculi, kidney failure, and coagulation disorders. Cross-sectional imaging modalities, particularly multiphasic CT or MRI, are integral to the detection, localization, and characterization of the underlying causes and facilitate optimal management. However, large-volume hemorrhage at patient presentation may obscure underlying causes, particularly neoplasms. If the initial CT or MRI examination shows no contributary causes, a dedicated CT or MRI follow-up study may be warranted to establish the cause of WS. Renal arterial embolization is a useful, minimally invasive, therapeutic option in patients who present with acute or life-threatening hemorrhage and can help avoid emergency radical surgery. Accurate diagnosis of the underlying cause of WS is critical for optimal patient treatment in emergency and nonemergency clinical settings. ^©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

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.

Embolization in Pediatric Patients: A Comprehensive Review of Indications, Procedures, and Clinical Outcomes

Embolization in pediatric patients encompasses a large spectrum of indications, ranging from the elective treatment of congenital diseases of the cardiovascular system to the urgent management of acute hemorrhagic conditions. In particular, the endovascular treatment of central and peripheral vascular malformations and hypervascular tumors represents a wide chapter for both congenital and acquired situations. Thanks to the progressive availability of low-profile endovascular devices and new embolic materials, the mini-invasive approach has gradually overtaken surgery. In this review, the main embolization procedures will be illustrated and discussed, with a focus on clinical indications and expected outcomes. The most recent mini-invasive techniques will be described, with hints on the cutting-edge devices and embolic materials.

Multidisciplinary, articular surface-preserving treatment strategy for locally aggressive epithelioid hemangioma of the acetabulum employing serial bland transarterial embolization

Epithelioid hemangioma is a rare, histologically benign but locally aggressive primary vascular neoplasm that can rarely arise in bone. Mainstay treatment is surgical resection or curettage with bone grafting. We report a novel multidisciplinary, joint-sparing treatment approach for an epithelioid hemangioma of bone arising in the acetabulum causing severe thinning of the subchondral bone plate. After 4 sessions of transarterial bland particle and ethanol embolization, the resultant increased ossification of the tumor allowed preservation of the articular surface during surgical resection. Imaging follow-up 14 months after surgical resection showed no evidence of recurrence and continued ossification of the portions of the lesion treated only with embolization.

Diffusion weighted imaging and diffusion kurtosis imaging in abdominal oncological setting: why and when

This article provides an overview of diffusion kurtosis (DKI) imaging in abdominal oncology. DKI allows for more data on tissue structures than the conventional diffusion model (DWI). However, DKI requires high quality images at b-values greater than 1000 s/mm² and high signal-to-noise ratio (SNR) that traditionally MRI systems are not able to acquire and therefore there are generally amplified anatomical distortions on the images due to less homogeneity of the field. Advances in both hardware and software on modern MRI scanners have currently enabled ultra-high b-value imaging and offered the ability to apply DKI to multiple extracranial sites. Previous studies have evaluated the ability of DKI to characterize and discriminate tumor grade compared to conventional DWI. Additionally, in several studies the DKI sequences used were based on planar echo (EPI) acquisition, which is susceptible to motion, metal and air artefacts and prone to low SNRs and distortions, leading to low quality images for some small lesions, which may affect the accuracy of the results. Another problem is the optimal b-value of DKI, which remains to be explored and not yet standardized, as well as the manual selection of the ROI, which could affect the accuracy of some parameters.

Transarterial Embolization for Sporadic Renal Angiomyolipoma: Patient Selection and Technical Considerations for Optimal Therapeutic Outcomes

Although renal angiomyolipoma (AML) is a benign tumor, treatment may be necessary occasionally because it can cause potentially life-threatening retroperitoneal hemorrhage. Transarterial embolization (TAE) is a safe and effective treatment option to prevent the hemorrhagic rupture of AMLs and relieve the symptoms caused by enlarged lesions or active bleeding. However, there is no clear consensus regarding the indications for prophylactic TAE in patients with sporadic renal AMLs. In urgent TAE for bleeding AMLs, there is a likelihood of incomplete embolization when the focus is on stabilizing the clinical symptoms. This pictorial essay discusses the patient selection and technical considerations to achieve optimal therapeutic effects as well as the follow-up findings after TAE.