Midterm Safety and Efficacy of Irreversible Electroporation of Malignant Liver Tumors Located Close to Major Portal or Hepatic Veins

Purpose To investigate the efficacy and safety of irreversible electroporation (IRE) in the treatment of hepatic tumors not suitable for thermal ablation (radiofrequency ablation [RFA] or microwave ablation). Materials and Methods This was an institutional review board-approved prospective study in 29 patients (15 men, 14 women; mean age, 63 years ± 12 [standard deviation]) with 43 primary (n = 8) or secondary (n = 35) malignant liver tumors who underwent computed tomography (CT)-guided IRE. All target tumors were located immediately adjacent to major hepatic veins, portal veins, or both; thus, they were not considered suitable for RFA or microwave ablation. Patients underwent postinterventional CT and magnetic resonance (MR) imaging. Systematic follow-up MR imaging was performed for 24 months on average to assess complete ablation, intrahepatic tumor recurrence, and complications. The 95% confidence intervals (CIs) were determined for the rate of bile duct strictures, incomplete ablation, and tumor recurrence. Results Complete ablation was achieved in 40 (93%; 95% CI: 85, 100) of 43 target tumors, with a safety margin of 5-10 mm, and was confirmed at immediate postinterventional CT and MR imaging. In 13 (33%; 95% CI: 18, 47) of 40 completely ablated tumors, intrahepatic tumor recurrence was observed at 2-18 months. However, only two (15%; 95% CI: 0, 35) of these 13 tumors were observed within the ablation zone. In the remaining 11 (85%; 95% CI: 65, 100), tumor growth was observed alongside the needle tract. None of the two true local recurrences occurred at the site of the vessel. All adjacent vessels remained perfused at follow-up. Five (24%; 95% CI: 5, 39) of 21 patients with target tumors adjacent to portal veins developed mild to moderate cholestasis 2-6 weeks after IRE. Conclusion IRE is useful to avoid incomplete ablation secondary to heat-sink effects and damage to major blood vessels; however, needle tract seeding is observed in 26% of treated tumors, and IRE induces sufficient local heating to bile ducts in 24% of ablations. ^© RSNA, 2017.

Interactive multi-criteria planning for radiofrequency ablation

PURPOSE

Image-guided radiofrequency ablation (RFA) is a broadly used minimally invasive method for the thermal destruction of focal liver malignancies using needle-shaped instruments. The established planning workflow is based on examination of 2D slices and manual definition of the access path. During that process, multiple criteria for all possible trajectories have to be taken into account. Hence, it demands considerable experience and constitutes a significant mental task.

METHODS

An access path determination method based on image processing and numerical optimization is proposed. Fast GPU-based simulation approximation is utilized to incorporate the heat distribution including realistic cooling effects from nearby blood vessels. A user interface for intuitive exploration of the optimization results is introduced.

RESULTS

The proposed methods are integrated into a clinical software assistant. To evaluate the suitability of the interactive optimization approach for the identification of meaningful therapy strategies, a retrospective study has been carried out. The system is able to propose clinically relevant trajectories to the target by incorporating multiple criteria.

CONCLUSIONS

A novel method for planning of image-guided radiofrequency ablation by means of interactive access path determination based on optimization is presented. A first retrospective study indicates that the method is suited to improve the classical planning of RFA.

Stentgraft Implantation for the Treatment of Postoperative Hepatic Artery Pseudoaneurysm

PURPOSE

Hepatic artery pseudoaneurysms are a rare but potentially life-threatening complication of major pancreaticobiliary surgery. We evaluated the safety and efficacy of endovascular stentgraft implantation for the management of such vascular lesions.

MATERIALS AND METHODS

Between May 2013 and October 2015, ten patients with postoperative hepatic artery pseudoaneurysm, of which eight presented with active hemorrhage, were treated with endovascular stentgraft implantation. All patients had undergone major pancreatic or hepatic surgery before (pylorus-preserving pancreaticoduodenectomy, pancreatectomy, hemihepatectomy, extended hemihepatectomy). The pseudoaneurysms were diagnosed 13-202 days after surgery and were associated with postsurgical complications (e.g., leakage of pancreaticojejunal anastomosis).

RESULTS

In 9/10 patients, the pseudoaneurysm was completely excluded via stentgraft implantation. In 1/10 patient, the pseudoaneurysm ruptured during the procedure and was successfully treated by immediate open surgery. In 1/10 patient, a second intervention was performed after 6 days because of rebleeding; this was successfully treated by implantation of a second overlapping stentgraft. Mean follow-up time is 51 days. None of the patients died due to stentgraft- or aneurysm-related complications. Further episodes of hemorrhage were not observed. In one patient, clinically asymptomatic complete occlusion of the stentgraft was discovered at follow-up imaging.

CONCLUSION

Stentgraft implantation is a safe and effective technique to treat hepatic artery pseudoaneurysms related to major pancreatic or hepatic surgery, especially in the setting of acute hemorrhage.

Low-Dose Chest CT for the Diagnosis of COVID-19—A Systematic, Prospective Comparison With PCR

BACKGROUND

Only limited evidence has been available to date on the accuracy of systematic low-dose chest computed tomography (LDCT) use in the diagnosis of COVID-19 in patients with non-specific clinical symptoms.

METHODS

The COVID-19 Imaging Registry Study Aachen (COVID-19-Bildgebungs-Register Aachen, COBRA) collects data on imaging in patients with COVID-19. Two of the COBRA partner hospitals (RWTH Aachen University Hospital and Dueren Hospital) systematically perform reverse transcriptase polymerase chain reaction (RT-PCR) from nasopharyngeal swabs as well as LDCT in all patients presenting with manifestations that are compatible with COVID-19. In accordance with the COV-RADS protocol, the LDCT scans were prospectively evaluated before the RT-PCR findings were available in order to categorize the likelihood of COVID-19.

RESULTS

From 18 March to 5 May 2020, 191 patients with COVID-19 manifestations (117 male, age 65 ± 16 years) underwent RT-PCR testing and LDCT. The mean time from the submission of the sample to the availability of the RT-PCR findings was 491 minutes (interquartile range [IQR: 276-1066]), while that from the performance of the CT to the availability of its findings was 9 minutes (IQR: 6-11). A diagnosis of COVID-19 was made in 75/191 patients (39%). The LDCT was positive in 71 of these 75 patients and negative in 106 of the 116 patients without COVID-19, corresponding to 94.7% sensitivity (95% confidence interval [86.9; 98.5]), 91.4% specificity [84.7; 95.8], positive and negative predictive values of 87.7% [78.5; 93.9] and 96.4% [91.1; 98.6], respectively, and an AUC (area under the curve) of 0.959 [0.930; 0.988]. The initial RT-PCR test results were falsely negative in six patients, yielding a sensitivity of 92.0% [83.4; 97.0]; these six patients had positive LDCT findings. 47.4% of the LDCTs that were negative for COVID-19 (55/116) exhibited pathological pulmonary changes, including infiltrates, that were correctly distinguished from SARS-CoV-2 related changes.

CONCLUSION

In patients with symptoms compatible with COVID-19, LDCT can esablish the diagnosis of COVID-19 with comparable sensitivity to RT-PCR testing. In addition, it offers a high specificity for distinguishing COVID-19 from other diseases associated with the same or similar clinical symptoms. We propose the systematic use of LDCT in addition to RT-PCR testing because it helps correct false-negative RT-PCR results, because its results are available much faster than those of RT-PCRtesting, and because it provides additional diagnostic information useful for treatment planning regardless of the type of the infectious agent.

Percutaneous transhepatic biliary drainage (PTBD) in patients with dilated vs. nondilated bile ducts: technical considerations and complications

Objectives

The aim of this study was to compare success, technical complexity, and complication rates of percutaneous transhepatic biliary drainage (PTBD) in patients with dilated vs. nondilated bile ducts.

Methods

In a retrospective analysis, we evaluated all consecutive PTBD performed in our department over a period of 5 years. Technical success, technical data (side, fluoroscopy time, radiation dose, amount of contrast media, use of disposable equipment), procedure-related complications and peri-interventional mortality were compared for patients with dilated vs. non-dilated bile ducts. Independent t test and χ² test were used to evaluate the statistical significance.

Results

A total of 253 procedures were performed on 187 patients, of whom 101/253 had dilated bile ducts and 152/253 not. In total, 243/253 procedures were successful. PTBD was significantly more often successful in patients with dilated vs. nondilated bile ducts (150/153 vs. 93/101; p 0.02). Overall complication rate (13%) did not differ significantly between patients with dilated vs. nondilated bile ducts. Procedures in patients with normal, nondilated bile ducts were associated with a significantly higher rate of post-interventional bleeding (5/101 vs. 0/152). Mean fluoroscopy time (42:36 ± 35:39 h vs. 30:28 ± 25:10 h; p 0.002) and amount of contrast media (66 ± 40 ml vs. 52 ± 24 ml; p 0.07) or use of disposables were significantly higher in patients with nondilated ducts. A significantly lower fluoroscopy time and amount of contrast medium were used in left hepatic PTBD.

Conclusion

Despite the higher technical complexity, PTBD with nondilated bile ducts was associated with similar overall complication rates but higher bleeding complications compared with PTBD with dilated bile ducts.

Key Points

• PTBD was associated with similar overall complication rates in patients with dilated vs. nondilated bile ducts.

• Although overall complication rates were low, PTBD in patients with nondilated bile ducts was associated with a higher incidence of post-interventional bleeding.

• PTBD in patients with nondilated bile ducts is technically more complex.

Stent Graft Placement by Pseudoaneurysm of the Hepatic Arteries: Efficacy and Patency Rate in Follow-up

Purpose

To investigate efficacy and patency status of stent graft implantation in the treatment of hepatic artery pseudoaneurysm.

Materials and Methods

A retrospective analysis of patients who had undergone endovascular treatment of hepatic artery pseudoaneurysms between 2011 and 2020 was performed. Medical records were examined to obtain patients’ surgical histories and to screen for active bleeding. Angiographic data on vascular access, target vessel, material used and technical success, defined as the exclusion of the pseudoaneurysm by means of a stent graft with sufficient control of bleeding, were collected. Vessel patency at follow-up CT was analyzed and classified as short-term (< 6 weeks), mid-term (between 6 weeks and 1 year), and long-term patency (> 1 year). In case of stent occlusion, collateralization and signs of hepatic hypoperfusion were examined.

Results

In total, 30 patients were included and of these, 25 and 5 had undergone stent graft implantation and coiling, respectively. In patients with implanted stent grafts, technical success was achieved in 23/25 patients (92%). Follow-up CT scans were available in 16 patients, showing stent graft patency in 9/16 patients (56%). Short-term, mid-term, and long-term short-term stent patency was found in 81% (13/16), 40% (4/10), and 50% (2/4). In patients with stent graft occlusion, 86% (6/7) exhibited maintenance of arterial liver perfusion via collaterals and 14% (1/7) exhibited liver abscess during follow-up.

Conclusion

Stent graft provides an effective treatment for hepatic artery pseudoaneurysms. Even though patency rates decreased as a function of time, stent occlusion was mainly asymptomatic due to sufficient collateralization.

ALPPS versus two-stage hepatectomy for colorectal liver metastases--a comparative retrospective cohort study

Abstract

Background

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) and two stage hepatectomy with inter-stage portal vein embolization (TSH/PVE) are surgical maneuvers applied in patients with advanced malignancies considered unresectable by means of conventional liver surgery. The aim of this report is to compare the oncologic outcome and technical feasibility of ALPPS and TSH/PVE in the scenario of colorectal liver metastases (CRLM).

Methods

All consecutive patients who underwent either ALPPS or TSH/PVE for CRLM between 2011 and 2017 in one hepatobiliary center were analyzed and compared regarding perioperative and long-term oncologic outcome.

Results

A cohort of 58 patients who underwent ALPPS (n = 21) or TSH/PVE (n = 37) was analyzed. The median overall survival (OS) was 28 months and 34 months after ALPPS and TSH/PVE (p = 0.963), respectively. The median recurrence-free survival (RFS) was higher following ALPPS with 19 months than following TSH/PVE with 10 months, but marginally failed to achieve statistical significance (p = 0.05). There were no differences in morbidity and mortality after stages 1 and 2. Patients undergoing ALPPS due to insufficient hypertrophy after TSH/PVE (rescue-ALPPS) displayed similar oncologic outcome as patients treated by conventional ALPPS or TSH/PVE (p = 0.971).

Conclusions

ALPPS and TSH/PVE show excellent technical feasibility and comparable long-term oncologic outcome in CRLM. Rescue ALPPS appears to be a viable option for patients displaying insufficient hypertrophy after a TSH/PVE approach.

Microwave ablation compared with radiofrequency ablation for breast tissue in an ex vivo bovine udder model

PURPOSE

To compare the effectiveness of microwave (MW) ablation with radiofrequency (RF) ablation for treating breast tissue in a nonperfused ex vivo model of healthy bovine udder tissue.

MATERIALS AND METHODS

MW ablations were performed at power outputs of 25W, 35W, and 45W using a 915-MHz frequency generator and a 2-cm active tip antenna. RF ablations were performed with a bipolar RF system with 2- and 3-cm active tip electrodes. Tissue temperatures were continuously monitored during ablation.

RESULTS

The mean short-axis diameters of the coagulation zones were 1.34 ± 0.14, 1.45 ± 0.13, and 1.74 ± 0.11 cm for MW ablation at outputs of 25W, 35W, and 45W. For RF ablation, the corresponding values were 1.16 ± 0.09 and 1.26 ± 0.14 cm with electrodes having 2- and 3-cm active tips, respectively. The mean coagulation volumes were 2.27 ± 0.65, 2.85 ± 0.72, and 4.45 ± 0.47 cm(3) for MW ablation at outputs of 25W, 35W, and 45W and 1.18 ± 0.30 and 2.29 ± 0.55 cm(3) got RF ablation with 2- and 3-cm electrodes, respectively. MW ablations at 35W and 45W achieved significantly longer short-axis diameters than RF ablations (P < 0.05). The highest tissue temperature was achieved with MW ablation at 45W (P < 0.05). On histological examination, the extent of the ablation zone in MW ablations was less affected by tissue heterogeneity than that in RF ablations.

CONCLUSION

MW ablation appears to be advantageous with respect to the volume of ablation and the shape of the margin of necrosis compared with RF ablation in an ex vivo bovine udder.

Correlation Between Sarcopenia and Growth Rate of the Future Liver Remnant After Portal Vein Embolization in Patients with Colorectal Liver Metastases

PURPOSE

To investigate whether sarcopenia and myosteatosis correlate with the degree of hypertrophy (DH) and kinetic growth rate (KiGR) of the future liver remnant (FLR) in patients with colorectal liver metastases undergoing portal vein embolization (PVE) in preparation for right hepatectomy.

MATERIALS AND METHODS

Forty-two patients were included. Total liver volume and FLR volume were measured before and 2-4 weeks after PVE. KiGR of the FLR was calculated. Sarcopenia was assessed using the total psoas muscle volume (PMV), the psoas muscle cross-sectional area (PMCS) and the total skeletal muscle index (L3SMI) at the level of 3rd lumbar vertebra. Degree of myosteatosis was assessed by mean muscle attenuation at L3 (L3MA). Correlations between muscle indices and DH and KiGR were assessed using simple linear regression analyses.

RESULTS

Mean DH was 8.9 ± 5.7%, and mean KiGR was 3.6 ± 2.3. Mean PMV was 55.56 ± 14.19 cm3/m3, mean PMCS was 8.76 ± 2.3 cm2/m2, mean L3SMI was 45.6 ± 9.89 cm2/m2, and mean L3MA was 27.9 ± 18.6 HU. There was a strong positive correlation between PMV and DH (R = 0.503, p = 0.001) and PMV and KiGR (R = 0.545, p < 0.001). Furthermore, there was a moderate correlation between PMCS and KiGR (R = 0.389, p = 0.014). L3SMI and L3MA were neither associated with DH (p = 0.390 and p = 0.768, respectively) nor with KiGR (p = 0.188 and p = 0.929, respectively).

CONCLUSION

We identified a positive correlation between PMV and PMCS, as markers for sarcopenia, and the KiGR of the FLR after PVE. PMV and PMCS might therefore aid to identify patients who are poor candidates for FLR augmentation using PVE alone.

Electroporation of the Liver: More Than 2 Concurrently Active, Curved Electrodes Allow New Concepts for Irreversible Electroporation and Electrochemotherapy

Irreversible electroporation and electrochemotherapy are 2 innovative electroporation-based minimally invasive therapies for the treatment of cancer. Combining nonthermal effects of irreversible electroporation with local application of chemotherapy, electrochemotherapy is an established treatment modality for skin malignancies. Since the application of electrochemotherapy in solid organs is a promising approach, this article describes a novel electrode configuration and field generating method. For the treatment of hepatic malignancies, the shape of the electric field should resemble a spherical 3-dimensional geometry around the target tissue inside the liver. To adapt the actual shape of the field, the probe is designed in computer-aided design with a live link to a computer simulation software: Changes in design can be revalued quickly, regarding different quality criteria for field strength inside and outside the tumor. To rate these criteria, a set of formulas with weighting coefficients has been included. As a result of this design process, a needle-shaped prototype applicator has been built, designed for an intracorporal electroporation-based treatment. It can be used as percutaneous, image-guided, minimally invasive treatment option for malignant liver tumors. The shaft of the probe is used as central electrode and fitted with additional 4 expandable electrodes. These satellite electrodes are hollow, thus serving as injectors for chemotherapeutic agents within the area of the electric field. This configuration can be used for electrochemotherapy as well as irreversible electroporation. By placing 5 electrodes with just one needle, the procedure duration as well as the radiation dose can be reduced tremendously. Additionally, the probe offers an option to adapt the field geometry to the tumor geometry by connecting the 5 electrodes to 5 individually chosen electric potentials: By fine-tuning the ablation zone via the potentials instead of adjusting the location of the electrode(s), the procedure duration as well as the radiation dose will decrease further.

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.

A personalized approach to interventional treatment of tricuspid regurgitation: experiences from an acute animal study

OBJECTIVES

Interventional treatment of tricuspid valve disease has so far received little attention due to the anatomical challenges in a thrombogenic surrounding. In the present study, we present an imaging-based, personalized interventional approach to the therapy of tricuspid regurgitation.

METHODS

In our porcine model, we used rapid prototyping to build a matrix reproducing the geometry of the right atrium that was previously derived from computer tomography (CT) scans. Over this matrix, a braided nitinol device fitting almost completely the right atrium was crafted. An additional tubular stent component was developed to carry a tissue valve prosthesis. This part was designed to be connectable to the annular portion of the main device. In our feasibility study, the crimped device was implanted via jugular access into the right atrium of 12 pigs and expanded subsequently. Following isolated implantation of the device without the valve-carrying component, further procedures included implantation of the whole composite device, including the mentioned tissue valve. Representing a only feasibility study, all implantations were performed under full bypass and direct sight. On-site visualization was performed by both echocardiography and fluoroscopy. Additional imaging was realized by postoperative CT scans.

RESULTS

Following implantation, 9 of 12 animals were weaned from cardiopulmonary bypass. Correct positioning of the device and orthodromic blood flow as maintained by the valve prosthesis were demonstrated by echocardiography and fluoroscopy. Postoperative contrast CT evaluation demonstrated proper fitting of the device into the right-sided heart cavities without obstruction of the outflow tract. Autopsy additionally confirmed its correct positioning without major trauma to surrounding structures.

CONCLUSIONS

We demonstrated the feasibility in principle of a personalized interventional treatment for tricuspid regurgitation using a braided stent, based on individual cardiac imaging, with anchoring forces mainly exerted on the venae cavae and on the inner surface of the right atrium. The design process of this device is a good indicator of the growing potential of an imaging-based personalized simulation and production approach for the treatment of tricuspid valve disease.

The prognostic impact of preoperative body composition in perihilar and intrahepatic cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare but highly aggressive malignancy of the biliary system. Although it is amenable to surgical resection in early disease, outcomes are frequently dismal. Here, we investigated the prevalence of body composition (BC) alterations and their prognostic role for surgical patients with intrahepatic (iCCA) and perihilar (pCCA) disease. Patients undergoing curative‐intent surgery for iCCA or pCCA between 2010 and 2019 at University Hospital Aachen were included. Axial computed tomography images were retrospectively assessed with a segmentation tool (3D Slicer) at the level of the third lumbar vertebra to determine lumbar skeletal muscle (SM) index, mean SM radiation attenuation, and visceral fat area. The related BC pathologies sarcopenia, myosteatosis, visceral obesity, and sarcopenic obesity were determined using previously described cutoffs. A total of 189 patients (86 with iCCA, 103 with pCCA) were included. Alterations of BC were highly prevalent in iCCA and pCCA, respectively: sarcopenia, 33% (28/86) and 39% (40/103); myosteatosis, 66% (57/86) and 66% (68/103); visceral obesity, 56% (48/86) and 67% (69/103); sarcopenic obesity, 11% (9/86) and 17% (17/103). Sarcopenia and myosteatosis did not have a significant prognostic role for disease‐free survival (DFS) and overall survival (OS). Patients with iCCA with sarcopenic obesity (n = 9) had significantly shorter OS than patients without sarcopenic obesity (n = 7; log‐rank p = 0.002; median OS, 11 months and 31 months; 1‐year mortality, 55.6% [5/9] and 22% [17/77]; 5‐year mortality, 88.9% [8/9] and 61% [47/77], respectively). In multivariable analysis, only tumor‐related risk factors remained prognostic for DFS and OS. Sarcopenic obesity may affect clinical outcomes after curative‐intent surgery for iCCA, indicating that imaging‐based analysis of BC may hold prognostic value for long‐term survival and could aid preoperative patient selection.

Monitoring Liver Function of Patients Undergoing Transarterial Chemoembolization (TACE) by a 13C Breath Test (LiMAx)

PURPOSE

Transarterial chemoembolization (TACE) is associated with the risk of deteriorating liver function, especially in patients with preexisting liver damage. Current liver function tests may fail to accurately predict the functional liver reserve. Aim of this study was to investigate whether changes of liver function caused by TACE are associated with detectable changes of LiMAx values.

METHODS AND MATERIALS

Forty patients with primary or secondary liver cancer underwent TACE and LiMAx test on the day before, the day after, and 4 weeks after TACE. LiMAx results were evaluated, referenced to liver volume (CT/MR volumetry), correlated with the respective TACE volume (subsegmental vs. segmental vs. lobar), established liver function tests, and Child-Pugh and ALBI scores.

RESULTS

The individual LiMAx values were significantly reduced by 10% (p = 0.01) on the day after TACE and fully recovered to baseline 1 month after treatment. Similar changes were observed regarding levels of bilirubin, transaminases, albumin, INR, and creatinine. LiMAx did not correlate significantly with the treated liver volume, but did correlate with the baseline liver volume (< 1200 ml vs. > 1200 ml; p < 0.01). No significant changes were observed in the Child-Pugh score or ALBI score.

CONCLUSION

LiMAx is capable of detecting changes in liver function, even modulations caused by superselective TACE procedures. Accordingly, it could be used as a tool for patient selection and monitoring of transarterial therapy. In comparison, Child-Pugh and ALBI scores did not reflect any of these changes. Some biochemical parameters also changed significantly after TACE, but they tend to be less specific in providing sufficient information on actual cellular dysfunction.

EIT monitors valid and robust regional ventilation distribution in pathologic ventilation states in porcine study using differential DualEnergy-CT (ΔDECT)

It is crucial to precisely monitor ventilation and correctly diagnose ventilation-related pathological states for averting lung collapse and lung failure in Intensive Care Unit (ICU) patients. Although Electrical Impedance Tomography (EIT) may deliver this information continuously and non-invasively at bedside, to date there are no studies that systematically compare EIT and Dual Energy CT (DECT) during inspiration and expiration (ΔDECT) regarding varying physiological and ICU-typical pathological conditions such as atelectasis. This study aims to prove the accuracy of EIT through quantitative identification and monitoring of pathological ventilation conditions on a four-quadrant basis using ΔDECT. In a cohort of 13 pigs, this study investigated systematic changes in tidal volume (TV) and positive end-expiratory pressure (PEEP) under physiological ventilation conditions. Pathological ventilation conditions were established experimentally by single-lung ventilation and pulmonary saline lavage. Spirometric data were compared to voxel-based entire lung ΔDECT, and EIT intensities were compared to ΔDECT of a 12-cm slab of the lung around the EIT belt, the so called ΔDECT_Belt. To validate ΔDECT data with spirometry, a Pearson’s correlation coefficient of 0.92 was found for 234 ventilation conditions. Comparing EIT intensity with ΔDECT_(Belt), the correlation r = 0.84 was found. Normalized cross-correlation function (NCCF) between scaled global impedance (EIT) waveforms and global volume ventilator curves was r = 0.99 ± 0.003. The EIT technique correctly identified the ventilated lung in all cases of single-lung ventilation. In the four-quadrant based evaluation, which assesses the difference between end-expiratory lung volume (ΔEELV) and the corresponding parameter in EIT, i.e. the end-expiratory lung impedance (ΔEELI), the Pearson’s correlation coefficient of 0.94 was found. The respective Pearson’s correlation coefficients implies good to excellent concurrence between global and regional EIT ventilation data validated by ventilator spirometry and DECT imaging. By providing real-time images of the lung, EIT is a promising, EIT is a promising, clinically robust tool for bedside assessment of regional ventilation distribution and changes of end-expiratory lung volume.

Carbon dioxide-enhanced CT-guided placement of aortic stent-grafts: feasibility in an animal model

PURPOSE

To test the feasibility of carbon dioxide (CO(2))-enhanced computed tomography (CT)-guided placement of infrarenal abdominal aortic stent-grafts in an animal model.

METHODS

Appearance of a stent-graft mounted on its deployment system and the feasibility of CT fluoroscopy-guided placement were analyzed in an in vitro setting. Five domestic pigs weighing 70 to 80 kg underwent CO(2)-enhanced 64-slice CT arteriography (CTA). After surgical exposure of the right iliac artery, an 18-mm stent-graft was advanced into the abdominal aorta. Infrarenal position of the graft was monitored using CT fluoroscopy with CO(2) administered intermittently in a flow-regulated manner using a computer-controlled injection system. After the final position of the stent-graft was determined, the graft was deployed under CT fluoroscopy guidance. Graft position was confirmed by contrast enhanced 64-slice CTA and conventional catheter angiography. To quantitatively assess the position of the stent-graft, the distance between the proximal stent struts and the radiopaque marker was determined using an electronic caliper.

RESULTS

CT-guided placement of infrarenal aortic stent-grafts was feasible in all animals without complications. CO(2)-enhanced CTA allowed for the identification of the renal arteries in all animals. CT fluoroscopy permitted the continuous online monitoring of stent deployment. In all animals, the grafts were placed without impairment of renal artery flow or stent-graft dislocation. The mean distance between the stent-graft and origin of the more caudal renal artery was 0.9+/-0.3 mm.

CONCLUSION

CO(2)-enhanced CT fluoroscopy permits the precise placement of infrarenal aortic stent-grafts in an animal model.

Does Drug-Eluting Bead TACE Enhance the Local Effect of IRE? Imaging and Histopathological Evaluation in a Porcine Model

OBJECTIVES

We conducted an in vivo trial on swine to compare the ablation volumes of irreversible electroporation (IRE) followed by drug-eluting beads transarterial chemoembolization (DEB-TACE) versus IRE only.

MATERIALS AND METHODS

Nine swine underwent CT-guided IRE in one liver lobe and IRE immediately followed by DEB-TACE in a different liver lobe. For DEB-TACE, 100-300 µm beads (DC-Beads^®) were loaded with 50 mg doxorubicin. For IRE, the NanoKnife^® was used employing two electrodes according to the vendor's protocol. Imaging follow-up was performed including CT-based lesion volume assessment using contrast-enhanced CT (venous phase) on days 1, 3, and 7 after the procedure. Three animals were killed for histopathological analysis after each follow-up.

RESULTS

Ablation volumes in CT in the IRE + DEB-TACE group were 15.4 ± 10.5 ml on day 1, 8.7 ± 5.6 ml on day 3, and 1.6 ± 0.7 ml on day 7. In the IRE group, the corresponding values were 5.2 ± 5.2 ml on day 1, 1.0 ± 1.2 ml on day 3, and 0.1 ± 0.1 ml on day 7. On day 1 and day 3, ablation volumes of IRE + TACE group were significantly larger than in the IRE group (p < 0.05). 96% of beads were depicted in or around ablative lesions. 69% of these beads were found in the surrounding hemorrhagic infiltration and 31% within the ablative lesion itself.

CONCLUSIONS

Combination of IRE immediately followed by DEB-TACE resulted in larger ablation volumes compared to IRE alone, suggesting that local efficacy of IRE can be enhanced by post-IRE DEB-TACE.

Comparison of Chronologic Change in the Size and Contrast-Enhancement of Ablation Zones on CT Images after Irreversible Electroporation and Radiofrequency Ablation

Objective

To compare short-, mid-, and long-term follow-up ablation zone volume alterations as well as imaging features on contrast-enhanced computed tomography (CT) after irreversible electroporation (IRE) of primary and secondary liver tumors with findings subsequent to radiofrequency ablation (RFA).

Materials and Methods

Volume assessment of 39 ablation zones (19 RFA, 20 IRE) after intervention was performed at four time intervals (day 0 [t1; n = 39], day 1-7 [t2; n = 25], day 8-55 [t3; n = 28], after day 55 [t4; n = 23]) on dual-phase CT. Analysis of peripheral rim enhancement was conducted. Lesion's volume decrease relative to the volume at t1 was calculated and statistically analyzed with respect to patient's sex, age, ablation modality (IRE/RFA), and history of platinum-based chemotherapy (PCT).

Results

No influence of patient's sex or age on ablation volume was detected. The decrease in ablation zones' volume was significantly larger (p < 0.05 for all time intervals) after IRE (arterial phase, 7.5%; venous phase, 9.7% of initial volume) compared to RFA (arterial phase, 39.6%; venous phase, 45.3% of initial volume). After RFA, significantly smaller decreases in the ablation volumes, in general, were detected in patients treated with PCT in their history (p = 0.004), which was not detected after IRE (p = 0.288). In the arterial phase, peripheral rim enhancement was frequently detected after both IRE and RFA. In the venous phase, rim-enhancement was depicted significantly more often following IRE at t1 and t2 (pt1 = 0.003, pt2 < 0.001).

Conclusion

As per our analysis, ablation zone volume decreased significantly in a more rapid and more profound manner after IRE. Lesion's remodeling after RFA but not IRE seems to be influenced by PCT, possibly due to the type of cell death induced by the different ablation modalities.