Transarterial embolization (TAE) as add-on to percutaneous radiofrequency ablation (RFA) for the treatment of renal tumors: Review of the literature, overview of state-of-the-art embolization materials and further perspective of advanced image-guided tumor ablation.

Percutaneous radiofrequency ablation (RFA) for the treatment of stage I renal cell carcinoma has recently gained significant attention as the now available long-term and controlled data demonstrate that RFA can result in disease-free and cancer-specific survival comparable with partial and/or radical nephrectomy. In the non-controlled single center trials, however, the rates of treatment failure vary. Operator experience and ablation technique may explain some of the different outcomes. In the controlled trials, a major limitation is the lack of adequate randomization. In case reports, original series and overview articles, transarterial embolization (TAE) before percutaneous RFA was promising to increase tumor control and to reduce complications. The purpose of this study was to systematically review the literature on TAE as add-on to percutaneous RFA for renal tumors. Specific data regarding technique, tumor and patient characteristics as well as technical, clinical and oncologic outcomes have been analyzed. Additionally, an overview of state-of-the-art embolization materials and the radiological perspective of advanced image-guided tumor ablation (TA) will be discussed. In conclusion, TAE as add-on to percutaneous RFA is feasible and very effective and safe for the treatment of T1a tumors in difficult locations and T1b tumors. Advanced radiological techniques and technologies such as microwave ablation, innovative embolization materials and software-based solutions are now available, or will be available in the near future, to reduce the limitations of bland RFA. Clinical implementation is extremely important for performing image-guided TA as a highly standardized effective procedure even in the most challenging cases of localized renal tumors.

First human magnetic resonance visualisation of prosthetics for laparoscopic large hiatal hernia repair.

PURPOSE: Mesh repair of large hiatal hernias has increasingly gained popularity to reduce recurrence rates. Integration of iron particles into the polyvinylidene fluoride mesh-based material allows for magnetic resonance visualisation (MR). METHODS: In a pilot prospective case series eight patients underwent surgical repair of hiatal hernias repair with pre-shaped meshes, which were fixated with fibrin glue. An MR investigation with a qualified protocol was performed on postoperative day four and 3 months postoperatively to evaluate the correct position of the mesh by assessing mesh appearance and demarcation. The total MR-visible mesh surface area of each implant was calculated and compared with the original physical mesh size to evaluate potential reduction of the functional mesh surfaces. RESULTS: We documented no mesh migrations or dislocations but we found a significant decrease of MR-visualised total mesh surface area after release of the pneumoperitoneum compared to the original mesh size (mean 78.9 vs 84 cm(2); mean reduction of mesh area = 5.1 cm(2), p < 0.001). At 3 months postoperatively, a further reduction of the mesh surface area could be observed (mean 78.5 vs 78.9 cm(2); mean reduction of mesh area = 0.4 cm(2), p < 0.037). CONCLUSION: Detailed mesh depiction and accurate assessment of the surrounding anatomy could be successfully achieved in all cases. Fibrin glue seems to provide effective mesh fixation. In addition to a significant early postoperative decrease in effective mesh surface area a further reduction in size occurred within 3 months after implantation.

Applications of technical fusion in uroradiology.

Technical fusion is defined as the ultrasound-guided navigation through a previously generated 3 D imaging dataset such as a computed tomography (CT) or magnetic resonance imaging (MRI). This technique allows for moving the fused CT/MRI datasets synchroneously with the real-time ultrasound in the same plane. Established and furthermore not yet described applications, the technical principles and the limitations of this promising technique will be introduced.

[Time-resolved contrast-enhanced MR angiography of the lower limbs: solving the problem of venous overlap]. / Zeitaufgelöste MR-Angiografie der Becken-Bein-Etage: ein Lösungsansatz für das Problem der venösen Überlagerungen.

PURPOSE: The aim of this retrospective study was to evaluate peripheral MRA using time-resolved measurements at the femoral as well as the calf level with regard to the presence of unwanted venous overlap. MATERIALS AND METHODS: 150 patients were examined using a 1.5 T MRI unit for a three-step CE MRA approach with three partial injections of contrast agent (0.1 mmol/kg body weight of 1 molar contrast agent). Dynamic time-resolved measurements were used at the femoral as well the calf level. The images were analyzed with respect to the presence and grade of unwanted venous overlap as well as inadequate bolus timing. RESULTS: In all cases, MRA was technically successful. The overall image quality was assessed as excellent in 127 / 150 cases (84.7%), as mildly limited in 21 cases (14%) and as moderately limited, but still diagnostic in 2 cases (1.3%). No obvious overlap was found in 139 of 150 cases (92.7%). Non-diagnostically relevant minor overlap was found in 7 cases (4.6%) and non-diagnostically relevant moderate overlap in 4 cases (2.7%). Relevant venous overlap did not occur. Those 11 cases with minor or moderate overlap occurred at the calf level in 8 cases, at the calf and femoral level in 2 cases and at the femoral level only in one case. In 10 out of 11 cases, peripheral artery occlusive disease was classified as category IV (Fontaine). CONCLUSION: Three-step time-resolved CE MRA with dynamic measurements at the calf as well the femoral level can be considered as a safe and accurate technique for MRA of the lower limbs without significant venous overlap and without risk of inadequate bolus timing. Furthermore, it solves the problem of run time differences.