Evaluation of renal angiomyolipoma: correlation between Doppler ultrasound and angiography Poster No.: C-2058 Congress: ECR 2012 Type: Authors: Keywords: DOI: Scientific Paper M. D. Stern, Z. Dotan, Y. Kleinbaum, S. Katscherginsky, U. Rimon; Ramat Gan/IL Abdomen, Interventional vascular, Kidney, Catheter arteriography, Ultrasound-Colour Doppler, Comparative studies, Diagnostic procedure 10.1594/ecr2012/C-2058 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 14
Purpose Renal angiomyolipoma (AML) is a benign hamartomous tumor composed of adipose tissue, smooth muscle and abnormal, tortuous, aneurysmatic vessels constituing the angiogenic component of the tumor (figure 1). Most of them are sporadic (80%) whereas some are associated with Tuberosclerosis (20%). The main risk of AML is spontaneous rupture and massive retroperitoneal hemorrhage. Treatment has shifted from surgery, i.e nephrectomy, to nephron sparing procedures such as selective embolization of the angiogenic component, partial nephrectomy and radiofrequincy (RF) ablation. The technical success of embolization is over 90%, and recurrence rate up to 30% seen in tuberosclerosis patients[1, 2,3,4]. Classically, there is an indication to treat tumors larger than 4 cm, because more than 50% of them bleed at some point[5]. A correlation has been shown between tumor size, aneurysm formation and spontaneous rupture [6]. Moreover, tumors whose angiogenic component shows marked vascularity on angiographic studies more likely require treatment [7]. Although follow up of patients after embolization has been performed with contrast enhanced CT in most published studies, no imaging regimen for follow up of the angiogenic component is yet recommanded [8]. Doppler ultrasound is a well accepted, none invasive, devoid of radiation imaging method that particularly define blood vessels, and pattern of vascularization [9] but it was not yet used to evaluate the AML's angiogenic component as compared to angiography. The purpose of our study is to compare Doppler ultrasound to angiography in characterizing angiomyolipoma angiogenic component and to recommend this technique for follow up after embolization. Images for this section: Page 2 of 14
Fig. 1: typical anomalous vascularity termed "the angiogenic componant" of a renal angiomyolipoma as depicted by digital substraction angiography. Page 3 of 14
Methods and Materials This is a retrospective study, authorized by the ethical commitee of our institution. Patients included in the study have known large angiomyoplipoma(aml), diagnosed by prior contrast enhanced CT (CECT), and underwent angiographic procedure for selective embolization of renal AML between the years 2005 to 2011. Renal Doppler ultrasound studies performed immediately before or after angiography and the correspondant angiographic studies were reviewed. Angiographic studies The angiographic studies were classified into 3 grades by an interventional radiologist blind to the ultrasound appearence of the tumor. The grading was performed on figures from selective catheterization of the renal artery or its branches : -before embolization, for those cases that ultrasound was performed before angiography -on post embolization figures when ultrasound was performed immeditely after embolization. the angiogenic component of AML was graded as follow: Grade 0: no vascularity - figure 2. Grade 1: minimal vascularity - figure 3. Grade 2: marked vascularity - figure 4. By our definition, only grade 2 tumors require intervention. Doppler ultrasound studies The Doppler ultrasound studies were classified in 3 categories by an ultrasound radiologist blind to the tumor angiographic appearence and categorized as followed: Category 0: no doppler signal identified within the tumor- figure 5. Category 1: scattered punctate Doppler signal without any tortuous vessel identifiedfigure 6. Page 4 of 14
Category 2: at least one tortuous vessel is identified within the tumor- figure 7. DSA angiographic appearance is considered our gold standard for the characterisation of the angiogenic component of the tumors. Doppler ultrasound is considered to characterize correctly the angiogenic component of AML when the ultrasound category of the tumor equals their angiographic grade (3 levels classification). Ultrasound correctly depicts tumors needing treatment when it classifies grade 2 AML as category 2 and grade 0 or 1 AML as category 0 or 1 (2 levels classification). Statistical analysis The agreement between Doppler ultrasound and angiography was tested using Cohen's kappa test. The symmetry of disagreement was tested by Stuart-Maxwell test of symmetry. We both tested the agreement between the classifications (3 levels classification) and the agreement between modalities for the need to treat (2 levels classification). The statistical analysis was performed on the whole sample and on part of it, including only the studies when ultrasound was performed before the angiography (US before). Images for this section: Page 5 of 14
Fig. 1: typical anomalous vascularity termed "the angiogenic componant" of a renal angiomyolipoma as depicted by digital substraction angiography. Page 6 of 14
Fig. 2: Grade 0: The angiomyolipoma in the upper pole of the right kidney in contrast enhanced CT (CECT) coronal reformat shows no vascularity at DSA. Fig. 3: Grade 1: the angiomyolipoma in the lower pole of the right kidney in CECT coronal reformat,shows minimal vascularity at DSA and do not require treatment. Page 7 of 14
Fig. 4: Grade 2: the angiomyolipoma in the mid portion of the left kidney in CECT coronal reformat shows marked vascularity at DSA and rquire treatment. Fig. 6: Category 1: punctate color signal is detected within the angimyolipoma at the upper pole of the kidney at doppler ultrasound Page 8 of 14
Fig. 7: Category 2: at least one vessel is identified at Doppler ultrasound within the angiomyolipoma. Page 9 of 14
Fig. 5: Category 0: no color signal is shown within the angiomyolipoma in the upper pole of the right kidney at Power doppler ultrasound. Page 10 of 14
Results A total of 39 Doppler ultrasound studies were performed immediately before (21) or after (18) angiographic evaluation of renal angiomyolipoma. The tumor angiogenic component was correctly characterized by Doppler ultrasound in 26 cases out of 39 (66.7%) (table 1) and in 18 out of 21 (85.7%) when considering only ultrasound studies performed before angiography. In both situations the agreement is not high (Kappa=0.42 and 0.44) but highly significant. The need for treatment was correctly predicted by Doppler ultrasound in 34 cases out of 39 (87%) and in 19 out of 21(90%) when considering only ultrasound studies performed before angiography. In both situations the agreement is high (Kappa=0.74 and 0.61) and highly significant (table 2). When considering all the studies, Doppler ultrasound has a tendency to overclassified tumors as compared to the angiographic grade. The sensitivity of Doppler ultrasound to depict tumor needing treatment was 100% (95 % confidence interval [83.2%-100%]) and its specificity was 73.7% (95 % confidence interval [48.8%-90.9%]) for all the studies. The positive predictive value was 80% (95% confidence interval [59%-93%]), the negative predictive value was 100% (95% confidence interval [77%-100%]). When considering only ultrasound studies performed before angiography, the sensitivity of Doppler ultrasound to depict tumor needing treatment was 100% (95 % confidence interval [80.5%-100%]) and its specificity was 50% (95 % confidence interval [6.7%-93.2%]). The positive predictive value was 89.5% (95% confidence interval [67%-99%]), the negative predictive value was 100% (95% confidence interval [16%-100%]). Images for this section: Page 11 of 14
Table 1: 3 level classification repartitions of the tumors Page 12 of 14
Table 2 Page 13 of 14
Conclusion Our study suggests that Doppler ultrasound is a good imaging modality for detecting clinically relevant angiogenic component in renal AML. Renal Doppler ultrasound could be a practical imaging modality for follow up of AML patients, being both non invasive, devoid of radiation, unexpensive and very sensitive to the AML angiogenic component. References [1]Kothary N, Soulen MC, Clark TW, et al. Renal angiomyolipoma: long-term results after arterial embolization. J Vasc Interv Radiol 2005;16:45-50. [2]Mourikis D, Chatziioannou A, Antoniou A, et al. Selective arterial embolization in the management of symptomatic renal angiomyolipomas. Eur J Radiol 1999;32:153-9. [3]Han YM, Kim JK, Roh BS, et al. Renal angiomyolipoma: selective arterial embolization deffectiveness and changes in angiomyogenic components in long-term follow-up. Radiology 1997;204:65-70. [4]Ramon J, Rimon U, Garniek A, et al. Renal angiomyolipoma: long-term results following selective arterial embolization. Eur Urol; 2008 Apr [5]Oesterling JE, Fishman EK, Goldman SM, et al. The management of renal angiomyolipoma. J Urol 1986;135:1121-4. [6]Yamakado K, Tanaka N, Nakagawa T, et al. Renal angiomyolipoma: relationships between tumor size, aneurysm formation, and rupture. Radiology 2002;225:78-82. [7]Rimon U, Duvdevani M, Garniek A, et al. Large renal angiomyolipomas: digital subtraction angiographic grading and presentation with bleeding. Clin Radiol 2006;61:520-6. [8]Halpenny D, Snow A, Mc Neill G, et al.the radiological diagnosis and treatment of renal angiomyolipoma-current status.clin Radiol 2010; 99-108. [9]Jinzaki M, Ohkuma K, Tanimoto A et al. Small Solid Renal Lesions: Usefulness of Power Doppler US. Radiology 1998; 209:543-50. Personal Information Page 14 of 14