Induction of Contralateral Hepatic Hypertrophy by Unilobar Yttrium-90 Transarterial Radioembolization versus Portal Vein Embolization: An Animal Study.

PURPOSE: To compare hepatic hypertrophy in the contralateral lobe achieved by unilobar transarterial radioembolization (TARE) versus portal vein embolization (PVE) in a swine model. METHODS: After an escalation study to determine the optimum dose to achieve hypertrophy after unilobar TARE in 4 animals, 16 pigs were treated by TARE (yttrium-90 resin microspheres) or PVE (lipiodol/n-butyl cyanoacrylate). Liver volume was calculated based on CT before treatment and during 6 months of follow-up. Independent t-test (P < .05) was used to compare hypertrophy. The relationship between hypertrophy after TARE and absorbed dose was calculated using the Pearson correlation. RESULTS: At 2 and 4 weeks after treatment, a significantly higher degree of future liver remnant hypertrophy was observed in the PVE group versus the TARE group, with a median volume gain of 31% (interquartile range [IQR]: 16%-66%) for PVE versus 23% (IQR: 6%-36%) for TARE after 2 weeks and 51% (IQR: 47%-69%) for PVE versus 29% (IQR: 20%-50%) for TARE after 4 weeks. After 3 and 6 months, hypertrophy converged without a statistically significant difference, with a volume gain of 103% (IQR: 86%-119%) for PVE versus 82% (IQR: 70%-96%) for TARE after 3 months and 115% (IQR: 70%-46%) for PVE versus 86% (IQR: 58%-111%) for TARE after 6 months. A strong correlation was observed between radiation dose (median 162 Gy, IQR: 139-175) and hypertrophy. CONCLUSIONS: PVE resulted in rapid hypertrophy within 1 month of the procedure, followed by a plateau, whereas TARE resulted in comparable hypertrophy by 3-6 months. TARE-induced hypertrophy correlated with radiation absorbed dose.

Microwave Ablation in the Proximity of Surgical Clips: Is there a Safety Issue?

PURPOSE: The purpose of this study was to evaluate the heat generation of surgical clips within the target area of MWA and the influences on the ablation volume. MATERIALS AND METHODS: In bovine liver tissue, 42 ex vivo microwave ablations (60 W; 180 s) were performed. During ablation, the temperature was measured continuously at 4 points of interest (POI), in a distance of 7.5 and 15 mm on each side of the microwave antenna, with a titanium surgical placed at one 7.5-mm POI. Ablation volumes containing large vessels (n = 10) were excluded. For every POI, the mean temperature of 32 ablations was calculated. The mean temperatures were compared between the 4 POI and statistically analyzed using the Student's t test. RESULTS: The mean maximum temperatures at the side of the clip were 88.76 °C/ 195 s and 52.97 °C/ 195 s and at the side without clip 78.75 °C/ 195 s and 43.16 °C/ 195 s, respectively, at POI 7.5 mm and POI 15 mm. The maximum difference of mean temperatures for POI 7.5 mm was 12.91 °C at 84 s (p = 0.022) and for POI 15 mm 9.77 °C at 195 s (p = 0.009). No significant changes in size and shape of the ablation zone could be determined. CONCLUSIONS: Our study demonstrated significantly higher temperatures adjacent to surgical clips. Also, the temperatures distal to the titanium clip were higher compared to the control location without clip. These findings suggest an increased risk of thermal damage to surrounding tissues during MWA, especially in case of immediate contact to surgical clips.

Single-needle electroporation and interstitial electrochemotherapy: in vivo safety and efficacy evaluation of a new system.

OBJECTIVES: We conducted an in vivo trial to investigate the safety and efficacy of a newly developed system for the application of a combined therapy consisting of irreversible electroporation (IRE) and electrochemotherapy (IRECT) in the liver. The system is conceived as a single-needle multitined applicator with expandable electrodes that allow interstitial injection of fluids, e.g., chemotherapy. METHODS: Experiments were conducted in ten domestic pigs. The applicator was placed in different liver lobes under CT guidance. In one lobe, the applicator was used for conventional IRE (1500 V, 120 pulses, pulse length 100 µs). In the other lobe, the same procedure was performed preceded by the injection of a doxorubicin mixture through the expandable electrodes (IRECT). Contrast-enhanced CT and MRI were performed on days 1, 3, and 7 after the procedure. Accordingly, three animals were sacrificed on days 1, 3, and 7 after the imaging and ablation volumes were evaluated histopathologically. Related t test was used to compare the groups. RESULTS: Technical success was achieved in 9/10 experiments. One animal deceased during the intervention because of ventricular fibrillation. Follow-up CT 1 and 3 days after intervention showed a significant (p < 0.05) difference in the ablation volumes of IRECT vs IRE, respectively, of 4.47 ± 1.78 ml vs 2.51 ± 0.93 ml and of 3.39 ± 1.05 vs 1.53 ± 0.78 ml. CONCLUSIONS: IRECT using the newly developed system proved to be effective and provided significantly larger ablation volumes compared with IRE alone. However, ECG triggering is a necessary prerequisite to allow a safe application of the system. KEY POINTS: • Working on the geometry of the IRE applicator in terms of expandable electrodes may overcome the current limitations of IRE resulting from the placement of multiple electrodes. • Efficacy of IRE ablations can be enhanced by the interstitial application of chemotherapy in the periphery of ablation areas.

Median Arcuate Ligament Compression in Orthotopic Liver Transplantation: Results from a Single-Center Analysis and a European Survey Study.

Median arcuate ligament compression (MALC) potentially causes arterial complications in orthotopic liver transplantation (OLT). Here we aimed to investigate the incidence of MALC and its impact on clinical outcome after OLT. In addition, we performed an international survey among 52 European liver transplant centers to explore local protocols on the management of these patients. Data of 286 consecutive OLT recipients from a prospective database were analyzed retrospectively (05/2010-07/2017). Preoperative computed-tomography images were evaluated. Celiac axis stenosis due to MALC was found in 34 patients (12%). Intrinsic stenosis was present in 16 (6%) patients. Twenty-six patients (77%) with MALC underwent standard arterial revascularization with median arcuate ligament (MAL)-division. Patients treated for MALC had comparable baseline data and no difference was found in early- and long-term outcome compared to the rest of our cohort. Our survey found heterogeneous strategies regarding diagnosis and treatment of MALC. Only 29% of the centers reported the division of MAL in these patients as routine procedure. Even though there is no consensus on diagnosis and management of MALC among European centers, a surgical division of MAL is feasible and safe and should be considered in OLT recipients with MALC.

Safety and Efficacy of Y-90 Radioembolization After Prior Major Hepatic Resection.

PURPOSE: To evaluate the safety and efficacy of yttrium-90 radioembolization (RE) following left or right hepatic lobectomy. MATERIALS AND METHODS: Between 2011 and 2016, 15 patients underwent RE with Y90-resin microspheres following right (8/15) or left (7/15) hepatic lobectomy. In eight patients, the whole liver remnant was treated during a single session, whereas the remaining seven patients received up to 3 selective RE at 1- to 2-month intervals. The administered patient activity was calculated based on the body surface area (BSA) method in all cases. In addition, CT-based volumetry of the liver remnant was performed and used to calculate the absorbed liver dose. Patient follow-up data were retrospectively analyzed regarding signs of radioembolization-induced liver disease (REILD), defined as occurrence of bilirubin >3.0 mg/dl and ascites within 1-2 months after treatment without tumor progression or bile duct occlusion. RESULTS: The mean volume of the liver remnant was 1.471 ± 341 ml, the mean administered amount of activity amounted to 1.31 ± 0.74 GBq, and the calculated mean absorbed dose was 42.8 ± 20.6 Gy. The early response to treatment was generally positive, with only one patient showing signs of progressive disease of the treated area on follow-up examinations within the first 2 months post-RE. None of the 15 patients developed a REILD. CONCLUSION: Y-90 radioembolization following extended hepatic lobectomy appears to be safe and effective. Although the standard BSA-based dosing seems to suffice to avoid REILD, it results in quite variable liver doses due to variable hypertrophy of the liver remnant post-hepatectomy. LEVEL OF EVIDENCE: Level IV, Case series.

Development and Evaluation of a Novel Curved Biopsy Device for CT-Guided Biopsy of Lesions Unreachable Using Standard Straight Needle Trajectories.

PURPOSE: To evaluate the feasibility of a novel curved CT-guided biopsy needle prototype with shape memory to access otherwise not accessible biopsy targets. METHODS AND MATERIALS: A biopsy needle curved by 90° with specific radius was designed. It was manufactured using nitinol to acquire shape memory, encased in a straight guiding trocar to be driven out for access of otherwise inaccessible targets. Fifty CT-guided punctures were conducted in a biopsy phantom and 10 CT-guided punctures in a swine corpse. Biposies from porcine liver and muscle tissue were separately gained using the biopsy device, and histological examination was performed subsequently. RESULTS: Mean time for placement of the trocar and deployment of the inner biopsy needle was ~205 ± 69 and ~93 ± 58 s, respectively, with a mean of ~4.5 ± 1.3 steps to reach adequate biopsy position. Mean distance from the tip of the needle to the target was ~0.7 ± 0.8 mm. CT-guided punctures in the swine corpse took relatively longer and required more biopsy steps (~574 ± 107 and ~380 ± 148 s, 8 ± 2.6 steps). Histology demonstrated appropriate tissue samples in nine out of ten cases (90%). CONCLUSIONS: Targets that were otherwise inaccessible via standard straight needle trajectories could be successfully reached with the curved biopsy needle prototype. Shape memory and preformed size with specific radius of the curved needle simplify the target accessibility with a low risk of injuring adjacent structures.

Preoperative Embolization of the Celiac Axis or Common Hepatic Artery before Distal Pancreatectomy with Resection of the Celiac Axis.

Patients with locally advanced pancreatic cancer who undergo distal pancreatectomy with resection of the celiac axis (CA) are at risk for postoperative hepatic or gastric ischemia if collateral blood flow from the superior mesenteric artery (SMA) via the gastroduodenal artery is insufficient. This study presents a technique for preoperative angiographic evaluation of these collateral vessels by using an AMPLATZER Vascular Plug to temporarily occlude the CA or common hepatic artery while simultaneously performing digital subtraction angiography of the SMA. If collateral vessels are deemed sufficient, the plug can subsequently be released for permanent occlusion with the intent to enhance the blood flow in these collateral vessels.

Endovascular placement of an extraluminal arterial bypass graft - in vitro feasibility study.

PURPOSE: A novel approach for arterial bypass grafting using exclusively endovascular techniques was established in-vitro in a phantom model. MATERIAL AND METHODS: The experimental setting consisted of a gel-wax phantom with two embedded parallel fluid-filled silicon tubes simulating the superficial femoral vessels. Through an 8-French sheath, a re-entry catheter (OUTBACK®, Cordis) was placed in the simulated artery and used to puncture the vascular wall. Then a 0.014-inch guide wire was advanced into the extravascular space. With the curved needle of the re-entry catheter, the guide wire was steered on a course parallel to the vessel wall in the extravascular space for 5-10 cm. At the desired reentry site, the re-entry catheter was used to puncture the vascular wall again in order to regain access to the endovascular space. Once the tip of the guide wire had safely been placed in the vascular lumen, a self-expandable stent graft (VIABAHN® GORE®) was deployed to complete the extraluminal bypass. RESULTS: Endovascular placement of an extraluminal bypass was successfully achieved in 20 attempts. The mean duration of the procedure amounted to 14:58 (minutes: seconds) (SD ± 3:56). CONCLUSIONS: This in-vitro study suggests that endovascular placement of an extraluminal arterial bypass graft is technically feasible.

CT of the normal temporal bone: comparison of multi- and single-detector row CT.

PURPOSE: To evaluate multi- and single-detector row computed tomographic (CT) depiction of anatomic landmarks of temporal bone. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained. In 50 temporal bones, transverse and coronal single-detector row CT images were compared with transverse and reformatted coronal multi-detector row CT images obtained of additional 50 temporal bones. Two radiologists evaluated images. Visibility of 50 landmarks was scored with a five-point quality rating scale. Fisher exact test, kappa statistics, and Mann-Whitney U test were used to evaluate imaging technique and landmark visibility. RESULTS: In delineating landmarks, total interobserver agreement was higher (P < .001) for transverse multi- than for single-detector row CT images. In 60% of landmarks, interobserver agreement was higher (P < .001) for transverse multi- than for single-detector row CT images. In 20% of landmarks, there was no difference, and in another 20% of landmarks, interobserver agreement was higher (P < .01) for single-detector row CT. Total interobserver agreement was higher (P < .01) for coronal multi-detector row reformations than for coronal single-detector row images. In 58% of landmarks, interobserver agreement was higher (P < .001) for coronal multi-detector row reformations than for coronal single-detector row images, while there was no difference in 8%. In 34% of landmarks, interobserver agreement was higher (P < .001) for coronal single-detector row images. Frequency of detected landmarks was higher for transverse (82%) and coronal (88%) multi-detector row images than for corresponding single-detector row images. In 72% of landmarks, transverse multi-detector row images were (P < .05) superior to corresponding transverse single-detector row images in landmark delineation. In 56% of landmarks, reformatted coronal multi-detector row images were (P < .05) superior to coronal single-detector row images in landmark delineation. CONCLUSION: Multi-detector row CT images, including reformations, better delineate temporal bone anatomy than do single-detector row CT images.