Endovascular aneurysm repair of abdominal aortic aneurysms: standards, technical options and advanced indications.

UNLABELLED: Since the introduction of endovascular aneurysm repair (EVAR) in 1991, the endovascular therapy with newest stent grafts has assumed a prominent role in the clinical management of abdominal aortic aneurysms (AAA) with a superior perioperative mortality of EVAR and an equivalent mid-term outcome, compared to open surgery. Newest techniques using chimney or periscope grafts and customized fenestrated and branched stent grafts allow the endovascular treatment of complex pararenal AAA. This article reviews EVAR in the treatment of AAA, evidence based results and advanced indication by newest interventional techniques and technical developments. KEY POINTS: • EVAR has become standard treatment of abdominal aortic aneurysm with equivalent results to open surgery.• Technical advancements and the introduction of newest stent grafts continually expand the indication of EVAR.• Chimney- and periscope grafts as well as custom-made prothesis systems allow endovascular treatment of complex para- and suprarenal aneurysms.

[CT-guided radiofrequency (RF) ablation of osteoid osteoma: clinical long-term results]. / CT-gesteuerte Radiofrequenz (RF)-Ablation von Osteoidosteomen: klinische Langzeitergebnisse.

PURPOSE: To evaluate CT-guided radiofrequency (RF) ablation of osteoid osteoma using internally cooled monopolar RF electrodes for technical success, complications and clinical long-term success. MATERIALS AND METHODS: Between April 1999 and July 2006, 23 patients were treated under general anesthesia with CT-guided RF ablation using an internally cooled monopolar single RF electrode (Cool-tip, Valleylab, TycoHealthcare, Boulder, USA; active tip: 10 mm). For the removal of the nidus, we used either a manual or an automated drill. The technical success was evaluated by a CT scan (MSCT, Siemens Medical Solutions, Forchheim). The clinical long-term success was investigated by questioning patients prior to discharge, and after 6, 12 and 18 months. After 18 months, patients were interviewed on an annual basis. RESULTS: The technical success rate was 100 %. The nidus was located in n = 19 cases at the lower extremity and in n = 4 cases at the upper extremity. Minor complications were observed for n = 2 patients. The mean hospitalization time was 1.5 d (1-2 d). The mean follow-up was 75.9 months (18-120 months) for n = 23 patients. No local recurrence was observed. One patient had intermediate pain one week after RF ablation without recurrent symptoms. CONCLUSION: CT-guided RF ablation using an internally cooled monopolar single RF electrode is an effective and safe minimally invasive method for the treatment of osteoid osteoma with excellent clinical long-term success.

Real-time MR fluoroscopy-navigated lumbar facet joint injections: feasibility and technical properties.

We prospectively evaluated the feasibility and technical properties of a dedicated interventional magnetic resonance (MR) imaging protocol for near-real-time MR fluoroscopy-guided bilateral lumbar facet joint injections. A total of 44 facet joint injections were performed in 22 patients using a C-shaped open 0.2-T MR imaging system (Magnetom Concerto, Siemens Medical Solutions, Erlangen, Germany). A T1/T2-weighted fast-imaging-with-steady-precession (FISP) sequence with an end-to-end latency of 1.2 s facilitated sufficient near real-time MR imaging guidance in all cases. A T1-weighted two dimensional fast-low-angle-shot (FLASH2D) MR sequence identified final needle tip location. Different angles of the needle path had only minimal influence on the appearance of the needle artifact produced by both sequences, resulting in a symmetrical needle tip artifact. The joint cavity was successfully punctured in 79.5% (35/44) of joints, which was followed by intra-articular fluid accumulation in 75% (33/44). Inaccessible joints demonstrated a significantly (p=0.044) higher number of posterior osteophytes (66.7%, 6/9 joints) compared to accessible joints (26%, 9/35 joints). No complications occurred. Table time showed significant shortening over time with average table time of 33 (21-68.5) min. We conclude that MR fluoroscopy-navigated lumbar facet joint injections are feasible and safe.

[Magnetic resonance imaging -- guided corticosteroid-infiltration of the sacroiliac joints: pain therapy of sacroiliitis in patients with ankylosing spondylitis]. / Magnetresonanzgesteuerte Kortikosteroid-Infiltration der Sakroiliakalgelenke: Schmerztherapie der Sakroiliitis bei Patienten mit Spondylitis ankylosans.

PURPOSE: To evaluate the efficacy and specific properties of MR imaging-guided corticosteroid infiltration of the sacroiliac (SI) joints in the treatment of therapy-refractory sacroiliitis in patients with ankylosing spondylitis. MATERIALS AND METHODS: In this study, 26 patients were prospectively included. Inclusion criteria were AS with therapy refractory acute sacroiliitis and inflammatory back pain > or = 6 months. The intervention was performed using an open low-field MR-scanner. Inflammatory back pain was assessed on a visual analog scale (VAS). Success of the therapy was defined as an absolute reduction of the VAS score or = 35 % and persisting improvement > or = 2 months. The grade of sacroiliitis was documented using high-field MR imaging. Variables were compared using McNemar test and Wilcoxon test. The mean remission time was calculated using a Kaplan-Meier analysis. A p-value < 0.05 was considered statistically significant. RESULTS: The intervention was technically successfully performed in all patients. Following MR imaging-guided corticosteroid infiltration of the SI joints, the VAS score improved from 8 (5 - 10) points to 4.5 (0 - 8) points (- 44 %) in all patients (n = 26), which was statistically significant (p < 0.001). Of 26 patients, 22 (85 %) fulfilled the predefined criteria for successful therapy. This group had a statistically significant (p < 0.01) improvement of the VAS score from 8 (6 - 10) to 3 (0 - 5) (- 63 %). Improvement was seen after 7 (1 - 30) days. There was a marked reduction of the subchondral bone marrow edema (- 38 %). The mean remission time was 12 (4 - 18) months. CONCLUSION: MR imaging-guided corticosteroid infiltration of the SI joints proved to be an effective therapy of inflammatory back pain in patients with therapy refractory AS. With the ability of multiplanar imaging, precise localization of the bone marrow edema and the lack of ionizing radiation, interventional MR imaging currently represents the superior method for the treatment of the predominantly young patient group presenting with ankylosing spondylitis. Owing to short intervention times, open MR-scanners are ideally suited for MR imaging-guided infiltration of the SI joints.

Contrast enhanced MR-guided biopsy of hepatocellular carcinoma.

Magnetic resonance (MR)-guided liver biopsy was performed in three patients with hepatocellular carcinoma. The tumor was considered (n = 2) or proven (n = 1) inaccessible with ultrasound or computed tomographic guidance. Because all lesions were poorly delineated on nonenhanced MR imaging, contrast agents (Gd-BOPTA, n = 1; ferucarbotran, n = 2) were applied to facilitate biopsy in an open low-field scanner. Postcontrast tumor conspicuity was fair in the patient receiving Gd-BOPTA and excellent in both patients receiving ferucarbotran, and biopsy was successful in all cases.

[Radiofrequency ablation ex vivo: comparison of the efficacy of impedance control mode versus manual control mode by using an internally cooled clustered electrode]. / Radiofrequenzablation ex-vivo: Vergleich der Effektivität von impedance control mode versus manual control mode unter Verwendung einer geschlossen perfundierten Cluster-Ablationssonde.

PURPOSE: To compare the effectiveness of pulsed (impedance control mode) and non-pulsed (manual control mode) radiofrequency ablation (RFA) by using an internal cooled-clustered electrode. MATERIALS AND METHODS: Ex vivo RF ablations (n = 93) were performed with a 200 W RF generator (Model-Cooled Tip, Radionics, USA) in 10 bovine livers, using the impedance and manual control mode. In the impedance control mode, the generator automatically adjusted the applied RF power to the tissue impedance measured during RF ablation. In the manual control mode, the application of the RF power was constant. Both applications were investigated in a capacity range between 5 and 200 W. The duration for each RF ablation was between 2 and 60 minutes. After RF ablation, the short axis diameter of the necrosis was determined macroscopically and the peripheral zone of the necrosis histologically. RESULTS: The impedance control mode produced lesions with short axis diameters of 5.3 +/- 0.3 cm at a power of 200 W after 60 minutes of RF ablation and the manual control mode lesions with short axis diameters of 4.1 +/- 0.4 cm at a power of 70 W after 8 +/- 2 minutes of RF ablation. The impedance control mode increased significantly the time of RF ablation with higher power and the size of necrosis (p < 0.01). CONCLUSION: In comparison to non-pulsed RF ablation, pulsed RF ablation with internal cooled-clustered electrodes significantly increases the size of the lesions and represents a methodical optimization in our opinion.

MR cholangiography in the diagnosis of sclerosing cholangitis in Langerhans' cell histiocytosis.

Langerhans' cell histiocytosis (LCH) is a disorder of histiocytic proliferation that primarily affects infants. Imaging findings of a rare case of lung and liver involvement in an adult are presented. High-resolution computed tomography (HRCT) of the lungs showed confluent thin-walled cystic air spaces compatible with advanced LCH. Liver CT and MRI revealed unspecific signs of fatty infiltration. Irregular widening of peripheral bile ducts was displayed in breath-hold MR cholangiography. This pattern is considered characteristic for sclerosing cholangitis and should support the diagnosis of LCH in case of concomitant cystic pulmonary disease, even in adult patients.

[Multidetector CT Angiography - is it a valuable screening tool to detect significant renal artery stenosis?]. / MDCTA der Nierenarterien - ein vollwertiges Screeningverfahren bei Nierenarterienstenose?

PURPOSE: To evaluate the diagnostic value of multidetector CT angiography (MDCTA) of the renal arteries. METHODS: 27 patients underwent MDCTA of the renal arteries. Scan parameters were: collimation 4 x 1 mm, pitch 1.5, effective slice thickness 1.25 mm, reconstruction increment 0.8 mm, circulation time measurement, power injection of 80 ml iomeprol 400, flow 4 ml/sec. Independent reading on laser film was done by two radiologists using edited maximum intensity projections, multiplanar reconstructions and source images. Standard of reference was a 3D-FLASH MR angiography (1.5 T, 3.9/1.2, 10 degrees 0.2 mmol GdDTPA/kg bw) in 10 and intraarterial angiography in 17 patients. RESULTS: Analysing 63 arteries, sensitivity, specificity, positive predictive value and negative predictive value in terms of detection of moderate and high grade renal artery stenosis (n = 10) were 90, 98, 90 and 98 % for reader A, and 90 % each for reader B, respectively (kappa = 0.91 interobserver agreement). 1/11 accessory renal arteries was missed by both angiography and MDCTA. Image quality was graded as excellent or good in 26/27 of cases by both readers. CONCLUSION: MDCTA proved to be a highly accurate tool in the detection of therapeutically relevant renal artery stenosis.

[Endovascular therapy of renal artery stenosis: technical results with the Palmaz-Corinthian stent]. / Endovaskuläre Therapie der Nierenarterienstenose: Technische Ergebnisse mit dem Palmaz-Corinthian-Stent.

OBJECTIVE: To evaluate the technical performance and delivery characteristics of the Palmaz-Corinthian stent for endovascular therapy of atherosclerotic renovascular disease. METHODS: 61 patients underwent implantation of 76 Palmaz-Corinthian (PC) stents in 72 arteries. 50 original PC and 26 PC stents with the modified IQ-design were employed. The indications comprised primary stenting of ostial (n = 49) or truncal (n = 1) stenosis or occlusion (n = 3), and selective stenting following complicated (dissection, n = 4) or unsuccessful (n = 8) angioplasty. The remaining stents were placed in patients with recurrent stenosis (n = 5) or acute aortic dissection (n = 2) involving the renal artery. Mean severity and length of stenosis were 81.3% and 9.8 mm, respectively. 39 lesions were rated eccentric or calcified. Data on technical success, complication rate, delivery characteristics and ease of placement compared to standard renal stents were retrieved from a prospective multicenter registry. RESULTS: Stent delivery was successful in all patients, major complications were not reported. Stent placement was suboptimal in 7 of 72 cases: 4 stents were located too distally in the renal artery, necessitating proximal coaxial overstenting in 2 cases. The distal part of the stenosis was incompletely covered and the orifice of a segmental branch inappropriately overstented in one case each. One stent was dislodged from the balloon, resulting in stent protrusion in the aortic lumen. Significant residual stenosis after stenting was not observed. Overall stent deliverability, trackability and potential repositioning inside the stenosis were rated positive, radio-opacity was rated superior for the IQ design. CONCLUSION: Technical performance and delivery characteristics of the Palmaz-Corinthian stent have been significantly improved compared to the Palmaz design, allowing mostly correct placement in renal artery stenoses with a low complication rate.

[Primary tumors of the liver: radiologic interventional procedures]. / Primäre Tumore der Leber: Radiologisch-Interventionelle Verfahren.

Primary liver tumors are one of the most common malignant tumors worldwide. Surgical resection of the tumors is considered the only potentially curative therapy. It has been estimated that only 20%-30% of patients with HCC (hepatocellular carcinoma) are surgical candidates. For this reason a number of alternative therapies have been used for the treatment of HCC. These include transarterial chemoembolisation (TACE), percutaneous alcohol instillation (PAI) and thermal ablative techniques. Thermal ablation for the treatment of HCC include both freezing (cryoablation) and heating (radiofrequency, microwave, laser and high-intensity focussed sonography) techniques. Of these techniques, percutaneous radiofrequency ablation (PRFA) is increasingly used for the local tumor destruction. The low rate of complications and the technical development increasing the efficacy of PRFA have shown that this is a very promising and safe technique.

[Animal experiment studies on the effectiveness of permanent occlusion of the hepatic artery in transarterial chemoembolization]. / Tierexperimentelle Untersuchungen zur Effektivität der permanenten Okklusion der Arteria hepatica bei der Transarteriellen Chemoembolisation.

PURPOSE: To evaluate the effect of permanent occlusion of the hepatic artery on the efficacy of transarterial chemoembolization (TACE) in an animal model. MATERIAL AND METHODS: 12 days after inoculation of the Morris hepatoma 3924 A in 15 male ACI rats, TACE with Mitomycin C (0.25 mg/kgBW) + Lipiodol (0.2 ml/kgBW) without (n = 5) and with permanent occlusion of the hepatic artery (n = 5) was performed. Control group consisted of 5 rats. Tumor volume was determined by MRI (1.0 T, T1 [TR/TE, 400/14 ms]) before and 12 days after therapy. RESULTS: Compared to the control group, TACE without and with permanent occlusion of the hepatic artery showed a significant reduced tumor growth after 12 days (p = 0.017 and p = 0.005). However, permanent occlusion did not improve the retarding effect on tumor growth (p = 0.9). CONCLUSION: The effectiveness of TACE in an animal model using a cytostatic-/lipiodol-emulsion is not improved by permanent occlusion of the hepatic artery.

[Percutaneous radiofrequency ablation of hepatic neoplasms using a "cluster" electrode--first clinical results]. / Perkutane Radiofrequenzablation hepatischer Neoplasien unter Verwendung von "Cluster"-Ablationssonden--Erste klinische Erfahrungen.

PURPOSE: To evaluate feasibility, safety and efficacy of percutaneous radiofrequency ablation (RFA) of hepatic neoplasms using a clustered electrode. MATERIAL AND METHODS: Percutaneous, CT-guided RFA using a clustered electrode was performed in 12 patients with a total of 15 hepatic neoplasms (2.0-6.0 cm in diameter). RESULTS: A total of 17 percutaneous RFA was performed. The mean total procedure time was 2.0 h (1.5-2.5 h). Placement of the clustered electrode within the neoplasms using a inter- or subcostal approach under local anesthesia was possible in all cases. Complications related to percutaneous treatment and technical problems were not encountered. Diameter of the ablated areas ranged between 3.0-7.0 cm. Technical success was observed in 13 of 15 neoplasms (86.6%). During a mean follow-up of 7.25 months (range 3-12 months) 8 of 12 neoplasms showed a complete necrosis. CONCLUSION: Percutaneous RFA using a clustered electrode is a feasible, safe and effective procedure for the treatment of hepatic neoplasms up to 6 cm in size.

[MR venography of the deep leg veins: signal enhancement by volume infusion]. / MR-Venographie der tiefen Beinvenen: Signalsteigerung durch Volumeninfusion.

PURPOSE: To enhance flow signals in the deep veins of the lower extremity by means of a drip infusion. METHODS: Saline solution and diluted contrast media were consecutively administered in 8 healthy volunteers by drip infusion (3 ml/min) via the cubital vein. Imaging of the deep veins in both legs was performed using a gradient echo sequence with flow compensation. Changes of the intravascular signal-to-noise-ratio (SNR) were correlated with the duration of the drip infusion. RESULTS: Improved SNR were detected in each level examined in both thigh and calf. SNR increases up to 157% were opposed to decreases of less than 16%. The average rise of SNR was up to 55% in the calf veins. CONCLUSION: Saline drip infusion is a simple and valuable method for enhancement of venous flow signals and should be administered routinely in time-of-flight venographies.

[Contrast-enhanced MR cholangiography in percutaneous bile duct drainage]. / Kontrastverstärkte MR-Cholangiographie bei perkutaner Gallenwegsdrainage.

PURPOSE: To evaluate MR-cholangiography after instillation of contrast media via indwelling biliary tubes. METHODS: In 8 patients with stenoses of the central bile ducts, physiological saline solution and diluted contrast media (Gd-DTPA, 5 mmol/l) were consecutively administered via an indwelling biliary tube. MR cholangiograms were obtained before and after saline injection using a HASTE-sequence and after administration of Gd-DTPA using a T1-weighted gradient echo sequence. RESULTS: Peripheral bile ducts were better visualised in the water-sensitive approach than after Gd-DTPA enhancement. In patients with short-time drainage bile duct definition was poor due to periportal oedema. Visualisation of peripheral bile ducts could be improved by injection of saline solution in these patients. After administration of Gd-DTPA via the biliary tube contrast enhancement of the central bile ducts was achieved in all patients except for one patient on long-term drainage with an indwelling Yamakawa tube. CONCLUSION: T1-weighted visualisation of the central bile ducts can be achieved by means of injection of Gd-DTPA via indwelling biliary tubes.