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Accurately detecting inferior vena cava (IVC) filter complications is important for safe and successful retrieval as tip-embedded filters require removal with non-standard techniques. Venography prior to IVC filter retrieval has traditionally used a single anterior–posterior (AP) projection. This study compares the utility of rotational venography to AP venography prior to IVC filter removal. The rotational venograms from 100 consecutive IVC filter retrievals over a 35-month period were evaluated retrospectively. The AP view of the rotational venogram was examined separately from the full series by a radiologist blinded to alternative imaging and operative findings. The venograms were evaluated for tip embedding, filter fracture, filter thrombus, and IVC thrombus. Statistical analysis was performed. Using operative findings and peri-procedural imaging as the reference standard, tip embedding occurred in 59 of the 100 filters (59 %). AP venography was used to correctly identify 31 tip-embedded filters (53 % sensitivity) with two false positives (95 % specificity) for an accuracy of 70 %. Rotational venography was used to correctly identify 58 tip-embedded filters (98 % sensitivity) with one false positive (98 % specificity) for an accuracy of 98 %. A significant difference was found in the sensitivities of the two diagnostic approaches (P

Although benign, renal angiomyolipoma (AML) may lead to serious complications without appropriate management. The purpose of this review is to describe the role of and evidence for interventional radiology techniques in the management of patients with AML. For patients with renal masses and non-diagnostic imaging studies, image-guided percutaneous biopsy is found to be highly accurate and useful in directing patient management. Once the diagnosis of AML has been made based on either imaging or biopsy, arterial embolization of tumors that are symptomatic or >4 cm has been demonstrated to reduce the risk of hemorrhage as well as tumor size. Percutaneous ablation devices have been proposed as alternative strategies but remain investigational. The utility of interventional radiology techniques including percutaneous core needle biopsy and prophylactic super-selective arterial embolization is safe and effective management strategies for patients presenting with AML tumors.

To the editor, We appreciate the interest of Jia et al. in our article ‘‘The Value of Rotational Venography Versus Anterior-Posterior Venography in 100 Consecutive IVC Filter Retrievals’’ [1]. Because this was not a surgical or necropsy-based study, an embedded filter tip was defined in our study by a composite reference of the standard imaging definition of lack of contrast around the filter tip along with the operative findings encountered during filter removal that required removal with endobronchial forceps. We feel this is a far more accurate definition compared with the timeand tiltbased definition proposed by the authors of the letter. Further, we prefer an evidence-based definition to a conjectural one. It has been elegantly shown that filter components can become embedded within 30 days [2] and likely sooner, given that the process of development of intimal hyperplasia in foreign bodies such as stents and filters begins immediately; one recent study of coronary stents showed [90 % strut coverage by 2 weeks [3]. The authors of the letter suggest, without any evidentiary basis, that 15 days is the minimum time needed to have a tip embedded filter. Given that there are no data to support this time-based definition, coupled with evidence in the literature to the contrary, their assertion that a filter removed at 11 days cannot be tip embedded is untenable. We thank Jia et al. for their interest in our work and appreciate the opportunity to further discuss the issue they raised. The issue raised by their letter, however, is not central to the importance of this study. The mean dwell time for filters in our study was 448 days and only 1 was removed at 11 days. Rotational venography can help interventionalists plan an appropriate approach to filter removal and avoid unsuccessful attempts to remove tipembedded filters using standard techniques which can occur if only AP venography is used. We stand by the conclusion of our study that ‘‘rotational venograms allow for more accurate detection of tip-embedded IVC filters compared to AP views alone.’’ Sincerely, S. William Stavropoulos, MD Scott O. Trerotola, MD Ryan M. Kiefer