Hydrodissection During Computed Tomography-Guided Cryoablation for Renal Tumors: Where is the Effective Fluid Accumulation Space in the Retroperitoneum?

PURPOSE: This study was performed to investigate the effectiveness of hydrodissection during computed tomography-guided renal cryoablation by evaluation of the fluid distribution based on the retroperitoneal anatomy with the interfascial plane. MATERIALS AND METHODS: Between March 2014 and March 2021, 52 renal tumors were treated by cryoablation with hydrodissection (36 men; mean age 72.5 years). The hydrodissection needle was located in perirenal space. The spreading fluid space based on the retroperitoneal anatomy with the interfascial plane was retrospectively evaluated. The fluid space that most effectively separated the tumor from the adjacent organs was defined. The relationship of the needle tip position in the perirenal space (renal capsule or fascia side) and the most effective fluid space was also evaluated. RESULTS: Cryoablation was successfully completed in all cases with no major complications. Hydrodissection was effective in all cases. The distance between the tumors and the adjacent organs was significantly longer after hydrodissection (from 7.50 ± 7.43 to 22.6 ± 9.86 mm) (P < 0.0001). Although fluid spreading through multiple retroperitoneal spaces was frequently observed, the retromesenteric plane was observed more frequently as the most effective fluid space (67.3%) than the perirenal space (21.2%) (P < 0.0001). Regardless of the needle tip position, the most effective fluid space was also commonly the retromesenteric plane. CONCLUSIONS: The retromesenteric plane could be the most effective fluid space to separate the tumor from the adjacent organ, regardless of where the hydrodissection needle tip is positioned in the perirenal space. LEVEL OF EVIDENCE: 3b.

Frequency and Risk Factors for Air Embolism in Computed Tomography Fluoroscopy-Guided Biopsy of Lung Tumor With the Use of Noncoaxial Automatic Needle.

PURPOSE: The aim of the study is to analyze incidence and risk factors for air embolism during computed tomography (CT) fluoroscopy-guided lung biopsies using noncoaxial automatic needle. MATERIALS AND METHODS: Between February 2014 and December 2019, 204 CT fluoroscopy-guided lung biopsies (127 men; mean age, 70.6 years) using noncoaxial automatic needle under inspiratory breath holding were performed. We retrospectively evaluated the incidence of air embolism as presence of air in the systemic circulation on whole-chest CT images obtained immediately after biopsy. Risk factors of the patient, tumor and procedural factors (size, location and type of nodule, distance from the pleura, the level of the lesion relative to the left atrium, emphysema, patient position, penetration of a pulmonary vein, etc) were analyzed. RESULTS: The technical success rate was 97.1%. Air embolism was radiologically identified in 8 cases (3.92%, 7 males; size, 21.6 ± 18.2 mm; distance to pleura, 11.9 ± 14.5 mm). Two patients showed overt symptoms and the others were asymptomatic. Independent risk factors were needle penetration of the pulmonary vein ( P = 0.0478) and higher location relative to left atrium ( P = 0.0353). Size, location and type of nodule, distance from the pleura, emphysema, patient position, and other variables were not significant risk factors. As other complications, pneumothorax and alveolar hemorrhage were observed in 57.4% and 77.5%, respectively. CONCLUSIONS: In CT fluoroscopy-guided lung biopsy using the noncoaxial automatic needles, radiological incidence of air embolism was 3.92%. Given the frequency of air embolism, it is necessary to incorporate this into postprocedure imaging and clinical evaluation.

Evaluation of Temperature Distribution Around the Probe in Cryoablation of Lipiodol-Mixed-Tissue Phantom.

PURPOSE: To determine whether lipiodol, which has low thermal conductivity, influences ice ball formation during cryoablation of a lipiodol-mixed-tissue phantom. MATERIALS AND METHODS: Lipiodol-mixed-tissue phantoms were created by injecting lipiodol (4-6 ml) into the renal arteries of ex vivo porcine kidneys (lipiodol group). A cryoprobe (CryoHit™ Needle S) with a holder that was set with thermocouples at various positions around the cryoprobe was inserted. After freezing for 300 s, the followings were evaluated: ice ball size on CT, temperature distribution around the cryoprobe, and calculated distances at 0 °C and - 20 °C. Each variable was compared between lipiodol group (n = 6) those obtained in a control group without lipiodol injection (n = 6). RESULTS: Mean ice ball diameter (width/length) on CT was 22.1 ± 2.3/22.9 ± 2.3 mm in the lipiodol group and 21.6 ± 0.7/22.2 ± 1.3 mm in the control group. Mean cryoprobe temperature was - 118 ± 3.0 °C in the lipiodol group and - 117 ± 2.6 °C in the control group. In both groups, temperature at the 3 mm thermocouple reached approximately - 50 °C and was < 0 °C within ~ 10 mm of the cryoprobe. Temperature of 0/- 20 °C occurred at a mean distance from the cryoprobe of 11.1 ± 0.5/6.9 ± 0.4 mm in the lipiodol group and 11.0 ± 0.2/6.9 ± 0.2 mm in the control group. There was no significant difference in any variable between the groups. CONCLUSION: The inclusion of lipiodol in a tissue phantom had no negative effects on ice ball formation that were related to thermal conductivity.

Correction to: Reply to the letter: N-Butyl Cyanoacrylate-Lipiodol Mixture for Endovascular Purpose: Polymerization Kinetics Differences Between In Vitro and In Vivo Experiments.

We would like to correct one of the references that was listed incorrectly in our article.

Ice Ball Cracks on CT During Cryoablation for Renal Tumors: A Retrospective Analysis.

PURPOSE: To evaluate the frequency of ice ball cracks on CT during cryoablation of renal tumors and assess the severity of hemorrhagic complications associated with this finding. MATERIALS AND METHODS: Between March 2014 and March 2019, 130 patients underwent CT-guided cryoablation using cryoprobes with a diameter of 1.5 mm for 138 renal tumors (mean diameter, 23.6 mm; standard deviation [SD], 7.5; range, 8.3-43). Two blinded board-certified radiologists retrospectively reviewed the presence of cracks on CT obtained during the procedure. The incidence of major hemorrhage and changes in hemoglobin levels after cryoablation were examined. Factors influencing the appearance of ice ball cracks were assessed with multivariate analyses. RESULTS: Cracks were observed in 25 of the138 procedures (18%). Inter-reader reliabilities with kappa statistics were 0.90 and 0.84 for first and second freeze sessions, respectively. There were no major hemorrhagic events requiring blood transfusion or arterial embolization. Mean (± SD) decreases in hemoglobin levels between pre- and postoperative day 1 were 1.15 ± 0.86 g/dl in the cracks group and 1.01 ± 0.80 g/dl in the no cracks group with no significant difference (p = 0.14). Multivariate analyses identified a higher number of cryoprobes (odds ratio, 4.1; 95% confidence interval [CI] 1.7-11; p = 0.001) and no hydrodissection (odds ratio 6.7; 95% CI 2.1-28; p < 0.001) as factors associated with ice ball cracks. CONCLUSION: Ice ball cracks were frequently observed on CT during cryoablation for renal tumors and were seemingly self-limiting events requiring no intervention.

Fundamental Evaluation of Thermophysical Properties of Lipiodol Associated with Cryoablation: Freezing Experiments Using Lipiodol Phantom.

PURPOSE: To elucidate the basic thermophysical properties at low temperatures of lipiodol, which is used as a marker by transarterial injection before CT-guided cryoablation for solid tumors, by fundamental experiments with pure lipiodol phantom. MATERIALS AND METHODS: The freezing point of lipiodol was measured using differential scanning calorimeter (DSC) by detecting differences in the heating rate during heating from - 30 °C. Freezing experiments were conducted using pure lipiodol and a tissue phantom, which were prepared in an acrylic container at 37 °C. The growth of the frozen region was observed for 10 min. Temperatures were monitored at the cryoprobe surface and designated positions around the cryoprobe. RESULTS: The DSC experiment showed that freezing was observed between - 5 and - 30 °C, which indicated that the freezing point was approximately - 5 °C. Freezing experiments revealed that the diameter of frozen region in the lipiodol was smaller than that in the tissue phantom (5 mm vs 24 mm) after 10-min freezing. The temperature at the probe surface was - 130 °C in lipiodol, which was 25 °C lower than that in the tissue phantom. There was a larger temperature gradient near the cryoprobe in lipiodol due to lower thermal conductivity. CONCLUSIONS: The present results suggest that an extremely high concentration of lipiodol (close to pure lipiodol) potentially reduces frozen region because of its lower freezing point and smaller thermal conductivity. However, since lipiodol concentrations in clinical cases differ from the current model, further studies using models that are close to clinical conditions are required. LEVEL OF EVIDENCE: No level of evidence, laboratory investigation.

Is the Cessation of Blood Flow Faster than the Polymerization of an n-Butyl Cyanoacrylate-Lipiodol Mixture? An In Vitro Phantom Study.

PURPOSE: To compare the polymerization time of n-butyl cyanoacrylate (NBCA) and lipiodol mixture in a static model and a pulsating flow model simulating embolization procedure of small caliber arteries. MATERIALS AND METHODS: The polymerization time of NBCA-lipiodol mixture was measured by the morphological changes of a glue droplet in a petri dish. For the flow model, we used a 2-mm-inner-diameter polyvinyl alcohol tube connected to a pulsation pump. Bovine serum was supplied from the pump and circulated into the system at 30 ml/min and 60 bpm. A 0.64-mm-inner-diameter silicon microcatheter was inserted into this system, and then, 0.5 ml of glue was injected into the tube. The flow cessation time was defined as the time it took to stop the serum draining from the end of the tube. Six samples of 100, 66, 50, 40, 33, and 20 vol% NBCA were assessed. RESULTS: The median polymerization times for each concentration were 0.12, 3.72, 12.30, 27.41, 57.68, and 63.67 s, respectively. The median flow cessation times were 0.28, 0.78, 1.43, 3.75, 4.50, and 9.29 s, respectively. The flow cessation time was significantly shorter than the polymerization time for all samples except for 100 vol% cyanoacrylate (p < 0.05). CONCLUSION: The flow cessation time of cyanoacrylate glue was significantly shorter than the polymerization time in an in vitro experiment. The injected glue possibly stops the blood flow before the completion of polymerization in the vascular system.

Ice Ball Crack During CT-Guided Renal Cryoablation Using 1.5-mm-Diameter Cryoprobes.

Ice ball fracture and massive hemorrhage are serious complications associated with renal cryoablation. When cracks occur in an ice ball, it is usually associated with adjacent renal parenchymal fracture, leading to massive hemorrhage. However, few studies have examined ice ball fracture under image-guided percutaneous renal cryoablation. We herein describe an 80-year-old male patient who had undergone CT-guided cryoablation for a left renal tumor using four cryoprobes (1.5 mm diameter each). Ice ball cracks were observed on CT images during cryoablation. However, there was no massive hemorrhage and further treatments were not necessary. This is the first report of ice ball cracks with a smaller diameter cryoprobe, which has not been considered to be associated with ice ball fracture.

Risk factors and clinical course of portal and/or splenic vein thrombosis after partial splenic embolization.

BACKGROUND: Although portal and/or splenic vein thrombosis after partial splenic embolization (PSE) is a well-known complication, few reports evaluating risk factors have been published. PURPOSE: To investigate risk factors and clinical course of portal and/or splenic vein thrombosis after PSE. MATERIAL AND METHODS: Sixteen patients with severe hypersplenism underwent PSE between March 2005 and April 2008. The correlation between portal and/or splenic vein thrombosis after PSE detected on multidetector row CT (MDCT) and various factors were retrospectively reviewed. Further, the clinical course of portal and/or splenic vein thrombosis after PSE was observed on follow-up MDCT. RESULTS: Splenic vein thrombosis was detected in eight patients (50%) on MDCT images taken within 9 days after PSE. In one, the thrombosis also involved the portal vein. The infarct volume was identified as a significant risk factor for portal and/or splenic vein thrombosis (P=0.046). In all but one patient, splenic vein thrombosis resolved completely or improved without anticoagulation therapy. In this patient, both portal and splenic vein thrombosis developed after PSE, and anticoagulation therapy was necessary. CONCLUSION: It is suggested that a large splenic infarct volume is a risk factor for portal and/or splenic vein thrombosis after PSE. Indications for treatment of thrombosis of the portal vein system after PSE may be limited to patients with portal vein thrombosis.

Transpulmonary radiofrequency ablation for hepatocellular carcinoma under real-time computed tomography-fluoroscopic guidance.

BACKGROUND/AIMS: Radiofrequency ablation has been accepted as a safe treatment for unresectable malignant hepatic tumors. Tumors beneath the diaphragmatic dome may be difficult to visualize with ultrasonography. The aim of this study was to assess the use of transpulmonary radiofrequency ablation under real-time computed tomography-fluoroscopic guidance for hepatocellular carcinoma. METHODOLOGY: Twenty-four radiofrequency ablation treatments by means of a transpulmonary approach were performed in 22 patients under computed tomography-fluoroscopic guidance between December 2002 and April 2006. Every patient had a hepatocellular carcinoma less than 3cm in size beneath the diaphragmatic dome. RESULTS: Transpulmonary radiofrequency ablation under real-time computed tomography-fluoroscopic guidance was successfully performed in every procedure. There was no local tumor recurrence in 22 cases (92%) on follow-up dynamic computed tomography performed an average of 8 months after radiofrequency ablation. The major complication was pneumothorax after 9 procedures (38%): pneumothorax in 6 patients had completely resolved on follow-up chest radiographs, and was treated with manual aspiration immediately after radiofrequency ablation in 3 patients, and no patients required chest-tube placement. CONCLUSION: Transpulmonary radiofrequency ablation under computed tomography-fluoroscopic guidance is a useful method for the accurate and safe ablation of hepatocellular carcinoma that is not detectable with ultrasonography.

Value of Micronester coils in port-catheter implantation for continuous hepatic arterial infusion chemotherapy with fixed catheter tip method.

To retrospectively evaluate the use of Micronester coils in port-catheter implantation with the fixed catheter tip method in comparison with other previously used coils. The cohort of this study was 143 consecutive patients with unresectable advanced liver cancer for whom a port-catheter system was percutaneously implanted. In the most recent 32 patients, Micronester coils were used for catheter tip fixation. Details of embolic agents for fixation, persistent blood flow beyond the distal end of the indwelling catheter, and complications were compared between cases without and with Micronester coils. In all, percutaneous port-catheter placement was successful. Mean number of coils used for fixation was 4.2 without Micronester coils vs. 2.5 with Micronester coils. N-butyl cyanoacrylate (NBCA)-Lipiodol was additionally used for catheter tip fixation in 85.6% of 111 procedures without Micronester coils and in 50% of 32 using Micronester coils. The gastroduodenal artery beyond the distal end was not detected at the final examination after any procedure. Catheter dislocation occurred in five and hepatic arterial obstruction or severe stenosis in eight. The number of coils used and necessity of NBCA-Lipiodol could be decreased with usage of Micronester coils without decreasing fixation ability compared to other coils.

Epinephrine-infused CTHA for HCCs.

BACKGROUND: Changes in the relative arterial flow to hepatocellular carcinomas and adjacent normal liver with hepatic arterial epinephrine infusion were studied with CT hepatic arteriography (CTHA). METHODS: Data from 31 pathologically confirmed hepatocellular carcinomas were retrospectively analyzed in 16 patients who simultaneously underwent CT during arterial portography (CTAP) and CTHA for examination of liver tumors and then CTHA with hepatic arterial epinephrine infusion. RESULTS: Regarding visual analysis, tumor enhancement of hepatocellular carcinomas on CTHA after hepatic arterial epinephrine injection changed as follows: more clear in 83.9% (26/31), equal in 16.1% (5/31), and less clear in 0% (0/31). As for the quantitative analysis, CT attenuation value of hepatocellular carcinomas significantly increased after injection of epinephrine (mean increase from 225.8 to 333.9 HU; P < 0.0001, paired t test). The CT attenuation value of normal liver parenchyma around a tumor significantly decreased after injection of epinephrine (mean decrease from 101.1 to 84.6 HU; P < 0.0001, paired t test). The tumor-to-liver conspicuity significantly increased after injection of epinephrine (mean increase from 124.6 to 249.2 HU; P < 0.0001, paired t test). CONCLUSIONS: Hepatic arterial epinephrine infusion changes the relative arterial flow of hepatocellular carcinomas.

Implantation of a port-catheter system through the superior mesenteric artery for repeated hepatic arterial infusion chemotherapy.

Between March 1999 and March 2006, 292 patients at the authors' institution required placement of a percutaneously implantable port-catheter system through which repeated hepatic arterial infusion chemotherapy would be administered. In 10 patients, the port-catheter system was implanted through the superior mesenteric artery. In these patients, implantation through the superior mesenteric artery instead of the celiac artery was necessary because all hepatic arteries arose from the superior mesenteric artery or because the blood supply to almost all tumors was from a hepatic artery arising from the superior mesenteric artery. Implantation of the port-catheter system was successful without complications in these 10 patients.

Risk factors for occurrence of local tumor progression after percutaneous radiofrequency ablation for lung neoplasms.

PURPOSE: To examine the characteristics of lung tumors for which radiofrequency (RF) ablation therapy is effective, and to determine what RF ablation parameters are effective for obtaining complete coagulation of the entire ablation zone with a single RF ablation session. MATERIALS AND METHODS: Computed tomography (CT)-guided RF ablation of lung tumors was performed on 82 lesions in 34 patients between April 2003 and May 2005. Tumor characteristics and ablation parameters, including tumor size, location, and depth, and ablation duration, power deployed during ablation, and temperatures achieved were analyzed with regard to local tumor progression. RESULTS: In all, 103 RF ablation sessions were performed on 82 tumors. As a procedure-related complication, pneumothorax occurred in 27 procedures. During the mean follow-up period of 10 months (range, 6-28 months), local tumor progression occurred in 18 (22.0%) of the 82 ablated tumors (3 months after RF ablation in 10, 6 months after RF ablation in 5, 9 months after RF ablation in 1, and 12 months after RF ablation in 2). Mean local progression-free duration was 8.7 +/- 4.5 months (range, 3-28 months). The frequency of local tumor progression was significantly correlated with size, whereas other variables had no statistical association. In tumors with a diameter > or =2.5 cm, only the period of ablation during the initial session was significantly correlated with subsequent local tumor progression (P = 0.000002, chi-square test). CONCLUSION: A long duration of RF ablation is desirable for large lung tumors. The success of RF ablation is dependent upon tumor size. RF ablation treatment is most effective for lesions < 2.5 cm.

Evaluation of retrievability of the Gunther tulip vena cava filter.

PURPOSE: To evaluate the feasibility and safety of withdrawal of a Gunther tulip retrievable vena cava filter (GTF). METHODS: Between June 2001 and December 2005, at our institution 86 GTFs were implanted for temporary caval filtration in 59 patients (37 women, 22 men; mean age 59.3 years, range 18-87 years). For GTFs retrieved thereafter, we retrospectively reviewed the following parameters: rate of success in retrieval, degree of trapped thrombus in the filter, and complications during retrieval. RESULTS: Worsening of or new development of pulmonary embolism after filter implantation did not occur in any patient. Of the 86 GTFs implanted, retrieval of 80 was attempted. Among those 80 filters, 77 (96%) were successfully retrieved (with the standard method, n = 72; with the modified method, n = 5) without any complication. The period of implantation of the retrieved filters was 13.4 +/- 4.2 days. In the 5 filters that were filled to a height of > or = 1/4 with trapped thrombus, retrieval was performed after attempts were made to decrease trapped thrombi. In addition, a temporary filter or another GTF was temporarily placed at the cephalad level of the GTF during this removal procedure. CONCLUSION: GTFs can be retrieved in the majority of cases. Even when encountering situations in which the filter could not be removed using the standard method, withdrawal was possible in a high frequency of cases through various trials using modified methods.

Use of a pull-through technique at the time of port-catheter implantation in cases of celiac arterial stenosis.

In four patients with a celiac artery that was too narrow through which to advance a catheter to the hepatic artery, a port-catheter system for hepatic arterial infusion chemotherapy was implanted with use of a pull-through technique. The indwelling catheter was advanced over a guide wire inserted from the femoral artery and through the celiac origin in a retrograde fashion via the superior mesenteric artery and pancreaticoduodenal collateral vessels. It was then pulled out via the infusion catheter access artery. In all cases, implantation with the fixed catheter tip technique was successful without complications.

Pneumothorax as a complication of percutaneous radiofrequency ablation for lung neoplasms.

PURPOSE: The present study was performed to determine the frequency of the complication of pneumothorax after radiofrequency (RF) ablation for lung neoplasms and risk factors affecting such pneumothoraces. MATERIALS AND METHODS: The study was based on 129 consecutive sessions of percutaneous RF ablation of lung neoplasms under real-time computed tomographic fluoroscopic guidance performed in a single institution between May 2003 and November 2005 in 41 patients (17 women, 24 men; mean age, 63 years; age range, 29-82 y). Correlation was determined between the incidence of pneumothorax after RF ablation and multiple factors: sex, age, presence of emphysema, lesion size, lesion depth, contact of tumor with pleura, number of punctures, maximum power of RF generator, period of ablation, tissue temperature at the end of the RF ablation session, and patient position during the procedure. Management of each case of iatrogenic pneumothorax was reviewed. RESULTS: Pneumothorax after RF ablation occurred in 38 of 129 RF ablation sessions (29.5%). Fourteen of the 38 cases were treated by manual aspiration, and 24 were simply observed. In five cases (3.9%), chest tube placement was required as therapy for pneumothorax. The risk of pneumothorax was significantly increased in patients with pulmonary emphysema. CONCLUSIONS: The frequency of pneumothorax after RF ablation in our experience is similar to the frequency of pneumothorax after lung biopsy reported in the literature. Various conditions for RF ablation did not influence the incidence of pneumothorax. Emphysema was the only individual factor that correlated significantly with the development of iatrogenic pneumothorax.

Usefulness and limitation of manual aspiration immediately after pneumothorax complicating interventional radiological procedures with the transthoracic approach.

The goal of this study was to evaluate the efficacy of simple aspiration of air from the pleural space to prevent increased pneumothorax and avoid chest tube placement in cases of pneumothorax following interventional radiological procedures performed under computed tomography fluoroscopic guidance with the transthoracic percutaneous approach. While still on the scanner table, 102 cases underwent percutaneous manual aspiration of a moderate or large pneumothorax that had developed during mediastinal, lung, and transthoracic liver biopsies and ablations of lung and hepatic tumors (independent of symptoms). Air was aspirated from the pleural space by an 18- or 20-gauge intravenous catheter attached to a three-way stopcock and 20- or 50-mL syringe. We evaluated the management of each such case during and after manual aspiration. In 87 of the 102 patients (85.3%), the pneumothorax had resolved completely on follow-up chest radiographs without chest tube placement, but chest tube placement was required in 15 patients. Requirement of chest tube insertion significantly increased in parallel with the increased volume of aspirated air. When receiver-operating characteristic curves were applied retrospectively, the optimal cutoff level of aspirated air on which to base a decision to abandon manual aspiration alone and resort to chest tube placement was 670 mL. Percutaneous manual aspiration of the pneumothorax performed immediately after the procedure might prevent progressive pneumothorax and eliminate the need for chest tube placement. However, when the amount of aspirated air is large (such as more than 670 mL), chest tube placement should be considered.

Withdrawal of port-catheter system for hepatic arterial infusion chemotherapy implanted with fixed catheter tip method.

PURPOSE: To evaluate the feasibility and safety of a method to withdraw port-catheter systems implanted by the fixed catheter tip method. MATERIALS AND METHODS: Retrospective review was conducted of 14 cases of unresectable advanced liver cancer in which it was necessary to attempt 15 withdrawals of percutaneously placed implantable port-catheter systems. Reasons for withdrawal, withdrawal success, complications, and subsequent treatment of patient were evaluated. RESULTS: In 14 of the 15 procedures (93.3%), the port-catheter system was successfully retrieved. Because continuation of hepatic arterial infusion chemotherapy was necessary in 10 procedures, a second implantation was performed after withdrawal of the initial catheter. Only one complication occurred, in which the indwelling catheter was broken in the aorta during withdrawal. CONCLUSION: When retrieval of a port-catheter system implanted with the fixed catheter tip method is necessary, withdrawal can be accomplished safely with high frequency.