Irreversible Electroporation Ablation of Malignant Hepatic Tumors: Subacute and Follow-up CT Appearance of Ablation Zones

PurposeTo describe findings on contrast-enhanced computed tomography (CT) images of malignant hepatic tumors 24–72 hours after percutaneous ablation by irreversible electroporation (IRE) and at midterm follow-up.Materials and MethodsRetrospective analysis of 52 malignant liver tumors—30 primary hepatic tumors and 22 hepatic metastases—in 34 patients (28 men and 6 women, mean age 64 y) treated by IRE ablation was performed. Ablation zones were evaluated by two examiners in a consensus reading by means of a dual-phase CT scan (consisting of a hepatic arterial and portal venous phase) performed 24–72 hours after IRE ablation and at follow-up.ResultsDuring the portal venous phase, ablation zones either were homogeneously hypoattenuating (n = 36) or contained heterogeneously isoattenuating or hyperattenuating (n = 16) foci, or both, in a hypoattenuating area. Of 52 lesions, 38 included gas pockets. Peripheral contrast enhancement of the ablation defect was evident in 23 tumors during the arterial phase and in 36 tumors during the portal venous phase. Four tumors showed intralesional abscesses after the intervention. At follow-up (mean, 4.7 mo), the mean volume of the ablation defects was reduced to 29% of their initial value.ConclusionsBecause normal findings on contrast-enhanced CT images after IRE ablation may be very similar to the typical characteristics of potential complications following ablation, such as liver abscesses, CT scans must be carefully analyzed to distinguish normal results after intervention from complications requiring further treatment.     

Irreversible Electroporation for Nonthermal Tumor Ablation in the Clinical Setting: A Systematic Review of Safety and Efficacy

PurposeTo provide an overview of current clinical results of irreversible electroporation (IRE), a novel, nonthermal tumor ablation technique that uses electric pulses to induce cell death, while preserving structural integrity of bile ducts and vessels.MethodsAll in-human literature on IRE reporting safety or efficacy or both was included. All adverse events were recorded. Tumor response on follow-up imaging from 3 months onward was evaluated.ResultsIn 16 studies, 221 patients had 325 tumors treated in liver (n = 129), pancreas (n = 69), kidney (n = 14), lung (n = 6), lesser pelvis (n = 1), and lymph node (n = 2). No major adverse events during IRE were reported. IRE caused only minor complications in the liver; however, three major complications were reported in the pancreas (bile leak [n = 2], portal vein thrombosis [n = 1]). Complete response at 3 months was 67%–100% for hepatic tumors (93%–100% for tumors < 3 cm). Pancreatic IRE combined with surgery led to prolonged survival compared with control patients (20 mo vs 13 mo) and significant pain reduction.ConclusionsIn cases where other techniques are unsuitable, IRE is a promising modality for the ablation of tumors near bile ducts and blood vessels. This articles gives an extensive overview of the available evidence, which is limited in terms of quality and quantity. With the limitations of the evidence in mind, IRE of central liver tumors seems relatively safe without major complications, whereas complications after pancreatic IRE appear more severe. The available limited results for tumor control are generally good. Overall, the future of IRE for difficult-to-reach tumors appears promising.     

Comparison of Simulation-based Treatment Planning with Imaging and Pathology Outcomes for Percutaneous CT-guided Irreversible Electroporation of the Porcine Pancreas: A Pilot Study

PurposeTo investigate the reliability of simulations for planning pancreatic irreversible electroporation (IRE) ablations compared with computed tomography (CT) and pathology outcomes in an animal model.Materials and MethodsSimulations were performed varying treatment parameters, including field strength (1.5–2.5 kV/cm), pulse number (70–90 pulses), and pulse length (70–100 µs). Pancreatic IRE was performed in six pigs under CT guidance. Two animals each were sacrificed for histology after 1 day, 14 days, and 28 days. Follow-up CT scans were performed on day 0, day 1, day 14, and day 28. Biochemical markers were collected before the procedure, 1 day after the procedure, and 14 days after the procedure.ResultsAll ablation zones could be visualized on CT scan immediately after the procedure and on day 1 follow-up CT scan, and all animals survived until the designated endpoints. Histopathology revealed necrosis and edema on day 1 and fibrosis and glandular atrophy after 28 days. Blood vessels close to the ablation zone appeared normal. Laboratory analysis indicated mild to moderate amylasemia and lipasemia with normalization after 14 days. The ablation size on CT scan measured a mean (± SD) 146% ± 18 (day 0, P < .126) and 168% ± 18 (day 1, P < .026) of the simulation and on pathology measured 119% ± 10 (day 1, not significant) of the simulation.ConclusionsResults from simulations for planning IRE ablations, CT, and pathology may differ from each other. Ablation zones on CT and pathology appear larger than simulated, suggesting that clinically used treatment planning may underestimate the ablation size in the pancreas.     

Evaluation of an Endorectal Electrode for Performing Focused Irreversible Electroporation Ablations in the Swine Rectum

PurposeTo study the feasibility of a novel endorectal electrode for the creation of focal ablations of the rectal wall with the use of irreversible electroporation (IRE).Materials and MethodsA monopolar electrode with a grounding pad (10 ablations in five pigs) and a bipolar electrode (two ablations in one pig) were evaluated in healthy swine rectum. A two-dimensional model of the electrode in the rectum was created and used to solve the Laplace equation to determine field strength. Simulation was used to identify treatment settings for superficial ablation (mucosal layers) or transmural ablation of rectal wall. Animals were euthanized within 4 hours after treatment.ResultsTreatment was successfully completed without treatment-related complications. Eleven of 12 lesions were successfully located and extracted for pathologic analysis. All lesions were characterized by necrotic cell death with mild inflammation and hyperemia, with a sharp demarcation between ablated and adjacent normal tissue. Depth of lesions corresponded with numeric simulation. Histologic analysis and measurements indicated that lesion creation with the superficial treatment setting resulted in ablation of mucosal and submucosal layers with superficial or no injury to the muscularis propria (9.97 mm ± 0.31 length, 3.3 mm ± 2.92 depth), and that lesion creation with the transmural treatment setting resulted in full-thickness ablation (12.43 mm ± 3.85 length, 4.97 mm ± 2.89 depth) of the rectal wall.ConclusionsAn endorectal electrode can be used to deliver IRE and create limited focal ablations in the rectal wall. Treatment parameters can be determined through numeric modeling to control the depth of penetration of ablation.     

Percutaneous Ablation of Peribiliary Tumors with Irreversible Electroporation

PurposeTo assess biliary complications after irreversible electroporation (IRE) ablation of hepatic tumors located < 1 cm from major bile ducts.Materials and MethodsA retrospective review was conducted of all percutaneous IRE ablations of hepatic tumors within 1 cm of the common, left, or right hepatic ducts at a single institution from January 2011 to September 2012. Computed tomography imaging performed before and after treatment was examined for evidence of bile duct dilatation, stricture, or leakage. Serum bilirubin and alkaline phosphatase levels were analyzed for evidence of biliary injury.ResultsThere were 22 hepatic metastases in 11 patients with at least one tumor within 1 cm of the common, left, or right hepatic duct that were treated with IRE ablations in 15 sessions. Median tumor size treated was 3.0 cm (mean, 2.8 cm ± 1.2, range, 1.0–4.7 cm). Laboratory values obtained after IRE were considered abnormal after four treatment sessions in three patients (bilirubin, 2.6–17.6 mg/dL; alkaline phosphatase, 130–1,035 U/L); these abnormal values were transient in two sessions. Two patients had prolonged elevation of values, and one required stent placement; both of these conditions appeared to be secondary to tumor progression rather than bile duct injury.ConclusionsThis clinical experience suggests that IRE may be a treatment option for centrally located liver tumors with margins adjacent to major bile ducts where thermal ablation techniques are contraindicated. Further studies with extended follow-up periods are necessary to establish the safety profile of IRE in this setting.     

Percutaneous Irreversible Electroporation for the Treatment of Colorectal Cancer Liver Metastases with a Proposal for a New Response Evaluation System

PurposeTo describe an initial experience with irreversible electroporation (IRE) in patients with colorectal liver metastasis (CLM).Materials and MethodsA retrospective analysis of patients undergoing IRE for the management of CLM was performed. Procedures were done percutaneously under general anesthesia. Patients were then followed for adverse events, tumor response, and survival.ResultsBetween March 2010 and February 2013, 29 patients underwent percutaneous ablation of 58 tumors in 36 IRE sessions. Most patients (89%) had an absolute or relative contraindication to thermal ablation. The median age was 62 years, and the median time from diagnosis to IRE was 28 months. The median number of lesions treated per patient was two, and the median tumor size was 2.7 cm. Patients had received previous chemotherapy regimens (range, 1–5 per patient). A new Metabolic Imaging And Marker Integration response evaluation criteria was used for response assessment, and was a predictor of progression-free and overall survival. The 2-year progression-free survival rate was 18% (95% confidence interval, 0%–35%), and the 2-year overall survival rate was 62% (95% confidence interval, 37%–87%). Complications included arrhythmias (n = 1) and postprocedure pain (n = 1). Both patients recovered without sequelae.ConclusionsPercutaneous IRE of CLM is feasible and safe. A new response evaluation system for colorectal cancer appears to be prognostic.     

Transcatheter CT Arterial Portography and CT Hepatic Arteriography for Liver Tumor Visualization during Percutaneous Ablation

PurposeTo evaluate the feasibility of combining transcatheter computed tomography (CT) arterial portography or transcatheter CT hepatic arteriography with percutaneous liver ablation for optimized and repeated tumor exposure.Materials and MethodsStudy participants were 20 patients (13 men and 7 women; mean age, 59.4 y; range, 40–76 y) with unresectable liver-only malignancies—14 with colorectal liver metastases (29 lesions), 5 with hepatocellular carcinoma (7 lesions), and 1 with intrahepatic cholangiocarcinoma (2 lesions)—that were obscure on nonenhanced CT. A catheter was placed within the superior mesenteric artery (CT arterial portography) or in the hepatic artery (CT hepatic arteriography). CT arterial portography or CT hepatic arteriography was repeatedly performed after injecting 30–60 mL 1:2 diluted contrast material to plan, guide, and evaluate ablation. The operator confidence levels and the liver-to-lesion attenuation differences were assessed as well as needle-to-target mismatch distance, technical success, and technique effectiveness after 3 months.ResultsTechnical success rate was 100%; there were no major complications. Compared with conventional unenhanced CT, operator confidence increased significantly for CT arterial portography or CT hepatic arteriography cases (P < .001). The liver-to-lesion attenuation differences between unenhanced CT, contrast-enhanced CT, and CT arterial portography or CT hepatic arteriography were statistically significant (mean attenuation difference, 5 HU vs 28 HU vs 70 HU; P < .001). Mean needle-to-target mismatch distance was 2.4 mm ± 1.2 (range, 0–12.0 mm). Primary technique effectiveness at 3 months was 87% (33 of 38 lesions).ConclusionsIn patients with technically unresectable liver-only malignancies, single-session CT arterial portography–guided or CT hepatic arteriography–guided percutaneous tumor ablation enables repeated contrast-enhanced imaging and real-time contrast-enhanced CT fluoroscopy and improves lesion conspicuity.     

Recanalization of Chronic Total Occlusions of the Superior Mesenteric Artery in Patients with Chronic Mesenteric Ischemia: Technical and Clinical Outcomes

PurposeTo evaluate the safety and outcomes of endovascular recanalization of chronic total occlusions (CTOs) of the superior mesenteric artery (SMA) in patients with chronic mesenteric ischemia (CMI).Materials and MethodsA single-institution retrospective review was performed of 47 consecutive patients (18 male, 29 female) who underwent endovascular stent placement for CTOs of the SMA between February 2006 and November 2012. All patients had symptoms of CMI. Procedural and follow-up data were collected for assessment of technical success, safety, and outcome.ResultsTechnical success was achieved in 41 of 47 patients (87%). Forty-two of the 47 procedures were performed from a femoral approach. Fifteen patients underwent concurrent revascularization of the celiac artery. All patients who underwent successful recanalization reported symptomatic improvement. Kaplan–Meier analysis revealed primary freedom from symptomatic recurrence of 95% at 12 months and 78% at 24 months. Symptomatic recurrence was observed in seven patients, all of whom underwent successful assisted or secondary endovascular procedures. Secondary freedom from symptomatic recurrence rates were 100% at 12 months and 88% 24 months. There were three (7%) minor access-related complications and no major complications.ConclusionsEndovascular stent-assisted recanalization of chronic SMA occlusions is safe and effective, with an acceptable rate of technical success and excellent midterm clinical outcomes.     

Quantitative Assessment of Lipiodol Deposition after Chemoembolization: Comparison between Cone-Beam CT and Multidetector CT

PurposeTo evaluate the ability of cone-beam computed tomography (CBCT) performed directly after transarterial chemoembolization to assess ethiodized oil (Lipiodol) deposition in hepatocellular carcinoma (HCC) and compare it with unenhanced multidetector computed tomography (CT).Materials and MethodsConventional transarterial chemoembolization was used to treat 15 patients with HCC, and CBCT was performed to assess Lipiodol deposition directly after transarterial chemoembolization. Unenhanced multidetector CT was performed 24 hours after transarterial chemoembolization. Four patients were excluded because the margin of tumor or area of Lipiodol deposition was unclear. The image enhancement density of the entire tumor and liver parenchyma was measured by ImageJ software, and tumor-to-liver contrast (TLC) was calculated. In addition, volumetric measurement of tumor and Lipiodol was performed by semiautomatic three-dimensional volume segmentation and compared using linear regression to evaluate consistency between the two imaging modalities.ResultsThe mean value of TLC on CBCT was not significantly different from TLC on multidetector CT (337.7 HU ± 233.5 vs 283.0 HU ± 152.1, P = .103).The average volume of the whole tumor and of only the regions with Lipiodol deposition and the calculated average percentage of Lipiodol retention on CBCT were not significantly different compared with multidetector CT (tumor volume, 9.6 cm³ ± 11.8 vs 10.8 cm³ ± 14.2, P = .142; Lipiodol volume, 6.3 cm³ ± 7.7 vs 7.0 cm³ ± 8.1, P = .214; percentage of Lipiodol retention, 68.9% ± 24.0% vs 72.2% ± 23.1%, P = .578). Additionally, there was a high correlation in the volume of tumor and Lipiodol between CBCT and multidetector CT (R² = 0.919 and 0.903).ConclusionsThe quantitative image enhancement and volume analyses demonstrate that CBCT is similar to multidetector CT in assessing Lipiodol deposition in HCC after transarterial chemoembolization.     

Renal Artery Fibromuscular Dysplasia in 2,640 Renal Donor Subjects: A CT Angiography Analysis

PurposeTo present the incidence, demographics, and clinical presentation of patients diagnosed with renal fibromuscular dysplasia (FMD) who underwent computed tomography (CT) angiography for evaluation of living renal donor protocol.Methods and MaterialsA retrospective review was performed from January 1, 2000, to December 31, 2011 on patients who underwent CT angiography for evaluation of living renal donor protocol. Of 2,640 patients identified, only patients with a diagnosis of FMD by the radiology report underwent independent reader evaluation of CT angiography for the presence of FMD and associated characteristics. The demographics, medical history, and presentation were reviewed using the electronic medical chart.ResultsThe independent readers who evaluated CT angiography identified a diagnosis of FMD in 68 patients (2.6%; 59 female) with an average age of 52 years ± 10. Unilateral FMD was observed in 46 patients (68%), and bilateral FMD was observed in 22 patients (32%). Three patients had aneurysms of the renal artery. Comorbidities included hypertension (n = 21, 31%), dyslipidemia, (n = 13, 19%), history of migraines (n = 3, 4%), and history of smoking (n = 14, 21%). No patients had diabetes mellitus, coronary artery disease, or family history of FMD. Of 21 patients (31%) with a history of hypertension, 13 patients (62%) were treated with antihypertensive medications.ConclusionsThe incidence of FMD in patients who underwent CT angiography for evaluation of living renal donor protocol is 2.6%.     

Transarterial Treatment of Colorectal Cancer Liver Metastases with Irinotecan-Loaded Drug-Eluting Beads: Technical Recommendations

Transcatheter hepatic arterial administration of irinotecan-loaded drug-eluting beads (DEBIRI) is used to treat liver-only or liver-dominant metastatic disease from colorectal cancer (CRC). Eligibility for DEBIRI should be established in each individual patient by a multidisciplinary team based on comprehensive clinical, imaging, and laboratory assessment. Standardization of DEBIRI technique and protocols would be expected to lead to improved efficacy and safety. The present article provides a set of technical recommendations for the use of DEBIRI in the treatment of hepatic CRC metastases.     

Microwave Ablation of Osteoid Osteomas Using Dynamic MR Imaging for Early Treatment Assessment: Preliminary Experience

PurposeTo evaluate the efficacy of microwave ablation for osteoid osteomas by using dynamic contrast-enhanced magnetic resonance (MR) imaging in early treatment assessment.Materials and MethodsTen patients (two female, eight male; mean age, 28 y; range, 16–47 y) presenting with osteoid osteomas were treated between June 2010 and December 2012 with the use of computed tomography (CT)–guided microwave ablation. Osteoid osteomas were found at the femoral neck (n = 4), tibia (n = 3), calcaneus (n = 1), navicular bone (n = 1), and dorsal rib (n = 1). Dynamic contrast-enhanced MR imaging at 3.0 T was performed 1 day before microwave ablation and again after ablation. The procedure was considered successful if the signal intensity (SI) of the lesion on MR imaging decreased by at least 50% and the patient was pain-free within 1 week of intervention.ResultsAll patients were pain-free within 1 week after microwave ablation and remained so during the 6 months of follow-up. No major or minor complications developed. On average, SI of the lesions decreased by 75% (range, 55.5%–89.1%) after treatment. The difference in lesion SI before versus after ablation was significant by t test (P < .0001; confidence interval, 120.26–174.96) and Wilcoxon test (P = .0020).ConclusionsMicrowave ablation treatment of osteoid osteoma was highly successful, without any complications observed. Dynamic contrast-enhanced MR imaging is a useful tool for diagnosing osteoid osteoma and evaluating treatment.     

Cone-beam CT: An Additional Imaging Tool in the Interventional Treatment and Management of Low-flow Vascular Malformations

PurposeTo evaluate the impact of cone-beam computed tomography (CT) during sclerotherapy of low-flow vascular malformations.Materials and MethodsEighty-seven cone-beam CT examinations were acquired during 81 sclerotherapy treatments of low-flow malformations in 48 patients: 81 were performed to evaluate sclerosing agent diffusion and six were performed to evaluate needle or catheter positioning before injection of therapeutic agent. Image quality was rated by two observers. Clinical impact of cone-beam CT in the assessment of therapeutic agent diffusion, needle or catheter positioning, subsequent treatment planning, and complication detection was evaluated. The κ-statistic was used to assess interobserver reliability and proportions, with associated 95% confidence intervals (CIs).ResultsAll cone-beam CT images were successfully acquired. Image quality was rated as excellent or good for the majority of studies, with substantial interobserver reliability (κ = 0.648). Cone-beam CT studies improved assessment of therapeutic agent diffusion in 83% of cases (67 of 81; 95% CI, 75%–91%) for observer 1, who had access to ultrasound, fluoroscopic, and digital subtraction angiographic (DSA) imaging, and in 95% of cases (77 of 81; 95% CI, 90%–100%) for observer 2, who had access to only stored fluoroscopic spot radiographs and DSA images. Cone-beam CT impacted planning of the next treatment session in 49% of cases (40 of 81; 95% CI, 38%–60%). In 7% of cases (six of 81; 95% CI, 1%–13%), complications such as migration of therapeutic agent or compression of upper airways were detected that were not seen with other imaging.ConclusionsCone-beam CT can be a useful adjunctive imaging tool, providing information to help decision-making during percutaneous sclerotherapy and ongoing management of low-flow vascular malformations.     

Early Treatment Response Evaluation after Yttrium-90 Radioembolization of Liver Malignancy with CT Perfusion

PurposeTo evaluate computed tomography (CT) perfusion for assessment of early treatment response after transarterial radioembolization of patients with liver malignancy.Materials and MethodsDynamic contrast-enhanced CT liver perfusion was performed before and 4 weeks after transarterial radioembolization in 40 patients (25 men and 15 women; mean age, 64 y ± 11; range, 35–80 y) with liver metastases (n = 27) or hepatocellular carcinoma (HCC) (n = 13). Arterial perfusion (AP) of tumors derived from CT perfusion and tumor diameters were measured on CT perfusion before and after transarterial radioembolization. Success of transarterial radioembolization was evaluated on morphologic follow-up imaging (median follow-up time, 4 mo) based on Response Evaluation Criteria in Solid Tumors (Version 1.1). CT perfusion parameters before and after transarterial radioembolization for different response groups were compared. Kaplan-Meier curves were plotted to illustrate overall 1-year survival rates.ResultsLiver metastases showed significant differences in AP before and after transarterial radioembolization in responders (P < .05) but not in nonresponders (P = .164). In HCC, AP values before and after transarterial radioembolization were not significantly different in responders and nonresponders (P = .180 and P = .052). Tumor diameters were not significantly different on CT perfusion before and after transarterial radioembolization in responders and nonresponders with liver metastases and HCC (P = .654, P = .968, P = .148, P = .164). In patients with significant decrease of AP in liver metastases after transarterial radioembolization, 1-year overall survival was significantly higher than in patients showing no reduction of AP.ConclusionsCT perfusion showed early reduction of AP in liver metastases responding to transarterial radioembolization; tumor diameter remained unchanged early after treatment. No significant early treatment response to transarterial radioembolization was found in patients with HCC. In patients with liver metastases, a decrease of AP after transarterial radioembolization was associated with a higher 1-year overall survival rate.     

Technical Details and Clinical Outcomes of Transpopliteal Venous Stent Placement for Postthrombotic Chronic Total Occlusion of the Iliofemoral Vein

PurposeTo evaluate the technical aspects and early clinical results of stent placement for managing postthrombotic chronic total occlusion (CTO) of the iliofemoral vein through ipsilateral popliteal access.Materials and MethodsA retrospective analysis of 110 patients (44 men; mean age, 51 y; 118 limbs; 102 left limbs) with postthrombotic CTO of the iliofemoral vein treated with stent placement in a single institution from January 2007–December 2011 was conducted. All occlusions were initially accessed via ipsilateral popliteal veins under the guidance of venography or ultrasonography. Technical aspects, quality of life, stent patency, and Villalta scores were recorded at follow-up evaluation. Risk factors of in-stent restenosis and early in-stent thrombosis were evaluated using Cox proportional hazards regression model.ResultsPercutaneous recanalization was successful in 112 of 118 limbs (95%). The mean duration of the procedure was 43 minutes (range, 10–120 min). The quality of life and Villalta scores were significantly improved (P < .01). The 3-year primary, assisted primary, and secondary cumulative stent patency rates were 70%, 90%, and 94%. During a median follow-up period of 25 months (range, 1–52 mo), the relief rates of severe leg pain (visual analog scale > 5) and severe leg swelling (grade 3) were 72% (49 of 68) and 70% (64 of 91), respectively, and the healing of ulcers was successful in 78% (36 of 46) of the cases. After stent placement, the limbs with visible remaining collateral circulation had a higher rate of early in-stent thrombosis (22.5% vs 6.1%; P = .007). The patients with long stents extending below the inguinal ligament had a higher rate of in-stent restenosis (hazard ratio = 1.77–6.5; P = .0146).ConclusionsTranspopliteal venous stent placement is an effective, safe, and feasible method of managing postthrombotic CTO of the iliofemoral vein. The stent extending below the inguinal ligament is the major risk factor of in-stent restenosis. The visible remaining collateral circulation after stent placement may indicate persistent hemodynamically significant stenosis.     

Percutaneous Cryoablation of Hepatic Tumors Adjacent to the Gallbladder: Assessment of Safety and Effectiveness

PurposeTo assess safety and effectiveness of percutaneous image-guided cryoablation of hepatic tumors adjacent to the gallbladder.Materials and MethodsTwenty-one cryoablation procedures were performed to treat 19 hepatic tumors (mean size, 2.7 cm; range, 1.0–5.0 cm) adjacent to the gallbladder in 17 patients (11 male; mean age, 59.2 y; range, 40–82 y) under computed tomography (n = 15) or magnetic resonance imaging (n = 6) guidance in a retrospective study. All tumors (mean size, 2.67 cm; range, 1.0–5.0 cm) were within 1 cm (mean, 0.4 cm) of the gallbladder; seven (33%) were contiguous with the gallbladder. Primary outcomes included complication rate and severity and postprocedure gallbladder imaging findings. Secondary outcomes included technical success and technique effectiveness at 6 months.ResultsComplications occurred in six of 21 procedures (29%); one (5%) was severe. Ice balls extended into the gallbladder lumen in 20 of 21 procedures (95%); no gallbladder-related complications occurred. The most common gallbladder imaging finding was mild, asymptomatic focal wall thickening after nine of 21 procedures (42%), which resolved on follow-up. Technical success was achieved in 19 of 21 sessions (90%). Six-month follow-up was available for 16 tumors; of these, all but two (87%) had no imaging evidence of local tumor progression.ConclusionsPercutaneous cryoablation of hepatic tumors adjacent to the gallbladder can be performed safely and successfully. Although postprocedural gallbladder changes are common, they are self-limited and clinically inconsequential, even when the ice ball extends into the gallbladder lumen.     

Morphologic Outcome after Endovascular Treatment of Complicated Type B Aortic Dissection

PurposeTo investigate the long-term morphologic changes of the aorta after thoracic endovascular aortic repair (TEVAR) for acute complicated type B aortic dissection and to analyze whether these changes differed between DeBakey class IIIa and IIIb dissections.Materials and MethodsDuring the period 1999–2009, 58 patients with acute complicated type B aortic dissection were treated with TEVAR. Seven patients lacked follow-up data, leaving 51 patients—17 patients with DeBakey IIIa aortic dissection and 34 patients with DeBakey IIIa aortic dissection IIIb—for inclusion in the study. Computed tomography scans performed before and after TEVAR were evaluated. Maximum thoracic and abdominal aortic diameters and diameters of the true lumen and false lumen at the level of the maximum aortic diameter in the thorax and abdomen were analyzed as well as degree of thrombosis of the false lumen.ResultsThere was an overall significant reduction of the thoracic aortic diameter, increased true lumen diameter, and reduced false lumen diameter (P < .05). Total thrombosis of the false lumen, with or without reintervention, was seen in 53% of all patients, in 41% primarily and in 12% after reintervention. The IIIa group had a higher degree of total false lumen thrombosis. All patients in the IIIb group had total thrombosis of the false lumen along the stent graft.ConclusionsLong-term follow-up showed favorable aortic remodeling after TEVAR for acute complicated type B aortic dissection. Total thrombosis of the false lumen occurred more often in patients with DeBakey IIIa aortic dissection compared with patients with DeBakey IIIb aortic dissection.     

Carbon Dioxide Contrast Enhancement for C-Arm CT Utility for Treatment Planning during Hepatic Embolization Procedures

A pilot study was performed to evaluate the use of carbon dioxide (CO₂) as a contrast medium for C-arm computed tomography (CT). C-arm CT using CO₂ was performed during embolization procedures in12 patients with hepatic malignancies and severe iodine allergy or high risk for nephrotoxicity. C-arm CT using gadolinium or iodinated contrast medium was performed for comparison. Of segmental arteries identified by conventional contrast enhancement, 96% were also seen with CO₂ enhancement, but subsegmental arteries were not reliably depicted. CO₂ enhancement identified 60% of tumors. Small, hypovascular, and infiltrative tumors were difficult to detect. CO₂ is a promising alternative intraarterial contrast agent for C-arm CT.     

Image Guidance for Endovascular Repair of Complex Aortic Aneurysms: Comparison of Two-dimensional and Three-dimensional Angiography and Image Fusion

PurposeTo evaluate the feasibility of image fusion (IF) of preprocedural arterial-phase computed tomography with intraprocedural fluoroscopy for roadmapping in endovascular repair of complex aortic aneurysms, and to compare this approach versus current roadmapping methods (ie, two-dimensional [2D] and three-dimensional [3D] angiography).Materials and MethodsThirty-seven consecutive patients with complex aortic aneurysms treated with endovascular techniques were retrospectively reviewed; these included aneurysms of digestive and/or renal arteries and pararenal and juxtarenal aortic aneurysms. All interventions were performed with the same angiographic system. According to the availability of different roadmapping software, patients were successively placed into three intraprocedural image guidance groups: (i) 2D angiography (n = 9), (ii) 3D rotational angiography (n = 14), and (iii) IF (n = 14). X-ray exposure (dose–area product [DAP]), injected contrast medium volume, and procedure time were recorded.ResultsPatient characteristics were similar among groups, with no statistically significant differences (P ≥ .05). There was no statistical difference in endograft deployment success between groups (2D angiography, eight of nine patients [89%]; 3D angiography and IF, 14 of 14 patients each [100%]). The IF group showed significant reduction (P < .0001) in injected contrast medium volume versus other groups (2D, 235 mL ± 145; 3D, 225 mL ± 119; IF, 65 mL ± 28). Mean DAP values showed no significant difference between groups (2D, 1,188 Gy·cm² ± 1,067; 3D, 984 Gy·cm² ± 581; IF, 655 Gy·cm² ± 457; P = .18); nor did procedure times (2D, 233 min ± 123; 3D, 181 min ± 53; IF, 189 min ± 60; P = .59).ConclusionsThe use of IF-based roadmapping is a feasible technique for endovascular complex aneurysm repair associated with significant reduction of injected contrast agent volume and similar x-ray exposure and procedure time.     

Hepatic Blood Volume Imaging with the Use of Flat-Detector CT Perfusion in the Angiography Suite: Comparison with Results of Conventional Multislice CT Perfusion

PurposeTo prospectively determine the feasibility of flat-detector (FD) computed tomography (CT) perfusion to measure hepatic blood volume (BV) in the angiography suite in patients with hepatocellular carcinoma (HCC).Materials and MethodsTwenty patients with HCC were investigated with conventional multislice and FD CT perfusion. CT perfusion was carried out on a multislice CT scanner, and FD CT perfusion was performed on a C-arm angiographic system, before transarterial chemoembolization procedures. BV values of conventional and FD CT perfusion were measured within tumors and liver parenchyma. The arterial perfusion portion of CT perfusion BV was extracted from CT perfusion BV by multiplying it by a hepatic perfusion index. Relative values (RVs) for CT perfusion arterial BV and FD CT perfusion BV (FD BV) were defined by dividing BV of tumor by BV of parenchyma. Relationships between BV and RV values of these two techniques were analyzed.ResultsIn all patients, both perfusion procedures were technically successful, and all 33 HCCs larger than 10 mm were identified with both imaging methods. There were strong correlations between the absolute values of FD BV and CT perfusion arterial BV (tumor, r = 0.903; parenchyma, r = 0.920; both P < .001). Bland–Altman analysis showed a mean difference of −0.15 ± 0.24 between RVs for CT perfusion arterial BV and FD BV.ConclusionsThe feasibility of FD CT perfusion to assess BV values of liver tumor and surrounding parenchyma in the angiographic suite was demonstrated.