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.

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.

Susceptibility weighted MRI after uterine artery embolization for leiomyoma.

PURPOSE: To evaluate whether susceptibility-weighted MR imaging (SWI) findings are associated with tumor infarction on contrast-enhanced MRI (CE-MRI) after uterine artery embolization (UAE) for leiomyoma. METHODS: This was a single institution, retrospective study. Between February 2016 and April 2017, 27 consecutive patients underwent UAE and completed SWI and CE-MRI before and 1 week after UAE. Two blinded readers independently reviewed the MRI of 261 tumors ≥1 cm in all patients. We evaluated the relationship between the hypointense peripheral rim observed on the tumor surface on post-procedural SWI and the infarction rates (≥90%, <90%) of each tumor based on post-procedural CE-MRI. Inter-reader correlation coefficients (ICC) and the sensitivity and specificity of the rim were measured. RESULTS: Substantial inter-reader agreement was noted in post-procedural SWI interpretations (ICC = 0.681, 95% CI; 0.547, 0.771). The rim was observed in 66.7% (174/261) of tumors by reader 1 and 55.9% (146/261) of tumors by reader 2 on post-procedural SWI. Correlations were observed between the rim and ≥90% tumor infarction by readers 1 and 2 (Spearman's coefficient = 0.474 and 0.438, p < 0.001 and p < 0.001, respectively). The sensitivity and specificity of the rim to tumor infarction were 77.2 and 82.6% (reader 1), and 65.8 and 100% (reader 2), respectively. CONCLUSIONS: The present study demonstrated that the hypointense peripheral rim was observed on some leiomyomas on SWI immediately after UAE. The rim correlated with tumor infarction on post-procedural CE-MRI. This SWI finding was helpful for evaluating embolic effects on leiomyomas in the acute phase after UAE.

Volume of embolic agents in uterine artery embolization for leiomyoma: relation to baseline MRI.

PURPOSE: To assess whether pre-procedural MRI findings predict the volume of tris-acryl gelatin microspheres (TAGM) used in uterine artery embolization (UAE) for leiomyomas. MATERIAL AND METHODS: This was a retrospective, single-institution study. Between June 2014 and December 2017, 73 patients with leiomyomas underwent UAE with TAGM alone. Univariate and multivariate analyses were performed to assess the relationships between the volume of TAGM and baseline parameters. Technical outcomes, tumor infarction on post-procedural contrast-enhanced MRI, and complications were evaluated. RESULTS: Technical success was achieved in all patients. Infarction of ≥90% of the total leiomyoma volume was observed in 93% (67/72) of patients. No major complications were noted. The mean (SD) volume of 500- to 700-µm particles used in all (73/73) patients was 10.3 ± 4.6 ml. The multivariate analysis revealed that uterine volume (p = .034) correlated with the 500- to 700-µm TAGM volume. Seven hundred- to 900-µm particles were added for 70% (51/73) of patients at a mean (SD) volume of 3.6 ± 4.6 ml. The dominant tumor volume (p = .028) correlated with the 700- to 900-µm TAGM volume. CONCLUSION: The dominant tumor or uterine volume on pre-procedural MRI was directly associated with the volume of TAGM required for embolization of leiomyomas.

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.

First Versus Second Uterine Artery Embolization for Symptomatic Leiomyoma.

OBJECTIVE: The purpose of this study was to compare the outcomes of second uterine artery embolization (UAE) with those of first UAE for symptomatic uterine leiomyoma. MATERIALS AND METHODS: In this single-institution retrospective study, between December 1997 and May 2016 first UAE was performed on 423 consecutively registered patients and second UAE on 11 consecutively registered patients to treat leiomyoma. The primary endpoint was infarction of all tumor tissue as seen at postprocedural contrast-enhanced MRI. The secondary endpoints were angiographic findings, embolization, MRI, and clinical outcomes 1 year after UAE. The outcomes were compared between the two groups. Multivariable linear regression analysis was performed to assess independent correlations with tumor infarction. RESULTS: Most of the baseline demographic features and technical outcomes in the two groups were similar. In the second UAE group, all but one uterine artery was reopened. More collateral vessels were observed at the second UAE (1.1/patient versus 0.23/patient, p = 0.043). Contrast-enhanced MRI after UAE revealed that the tumor infarction rate was significantly lower in the second UAE group (69.8 ± 33.9% vs 96.8 ± 9.0%, p = 0.025). The difference remained significant after adjustments for possible confounders (p < 0.001). Whether UAE was a first or a second procedure was significantly associated with tumor infarction rate (p < 0.001). The uterine volume reduction rate 1 year after UAE was significantly lower in the second UAE group (33.4 ± 18.1% versus 46.9 ± 16.6%, p = 0.008). No other 1-year outcomes were significantly different between the groups. CONCLUSION: Second UAE was effective but inferior to first UAE in that it resulted in less tumor infarction at contrast-enhanced MRI and had a lower uterine volume reduction rate.

Comparison of Pain Within 24 h after Uterine Artery Embolization with Tris-Acryl Gelatin Microspheres Versus Gelatin Sponge Particles for Leiomyoma.

PURPOSE: To compare acute pain after uterine artery embolization (UAE) with tris-acryl gelatin microspheres (TAGM) versus gelatin sponge particles (GS) for leiomyoma. MATERIALS AND METHODS: This was a single-institution, retrospective study. Between July 2008 and November 2016, 101 consecutive patients with symptomatic uterine leiomyoma underwent UAE with the same protocol for post-procedural pain. GS was employed with near-stasis endpoint for the first 49 patients, whereas TAGM was used with limited endpoint for the next 52 patients. Post-UAE pain levels were compared between both groups with a linear mixed model using visual analog scale (VAS) scores from 0 to 18 h as a repeat measure outcome. Peak VAS < 24 h or dose of drugs for analgesia and conscious sedation was compared by analysis of variance. Tumor infarction was assessed with post-procedural contrast-enhanced MRI. RESULTS: Baseline demographics and most outcomes including tumor infarction were similar between both groups. The average VAS scores during the period <24 h were significantly lower in TAGM group (1.68, 95% CI 1.23-2.13) compared to GS group (3.28, 95% CI 2.82-3.74, p < 0.0001). The difference remained significant even after adjustment for other factors (p < 0.0001). The mean peak VAS < 24 h was also lower in TAGM group (3.89, 95% CI 3.25-4.53) than in GS group (5.90, 95% CI 5.20-6.53, p < 0.0001). The dose of drugs for analgesia and conscious sedation was significantly lower in TAGM group (p = 0.001, p = 0.004, respectively). CONCLUSION: TAGM had an advantage over GS in UAE for leiomyoma in terms of less post-procedural pain <24 h, with lower doses of drugs for analgesia and conscious sedation.

Transcatheter arterial embolization with N-butyl cyanoacrylate for acute life-threatening gastroduodenal bleeding uncontrolled by endoscopic hemostasis.

PURPOSE: To investigate the feasibility, efficacy, and safety of transcatheter arterial embolization with N-butyl cyanoacrylate (NBCA) for gastroduodenal nonvariceal bleeding uncontrolled by endoscopic hemostasis. MATERIALS AND METHODS: Between January 2006 and December 2011, a total of 317 patients underwent emergent endoscopic therapy for nonvariceal gastroduodenal bleeding, but hemostasis was not achieved in 20 cases. Emergent surgery was performed immediately following endoscopy in two patients. Arteriography was performed in the remaining 18 patients, and embolization with NBCA was performed in 15 patients (mean age, 71.3 y) in whom the bleeding site was detected on arteriography. For embolization, NBCA was mixed with iodized oil at a ratio of 1:1.5-1:4, and no other embolic material was used in the procedure. Technical and clinical success rates, recurrent bleeding, procedural time, complications, and clinical outcomes were determined for each procedure. RESULTS: Embolization with NBCA was technically and clinically successful in all procedures, without major complications. No patient receiving embolization with NBCA experienced recurrent bleeding or required further treatment after the one-session procedure. All patients were discharged after clinical improvement. The time between puncture of the femoral artery and completion of embolization ranged from 25 to 240 minutes (mean, 66 min), and the time between the microcatheter reaching the ultimate catheter location selected for embolization and hemostasis ranged from 142 to 550 seconds (mean, 322s). CONCLUSIONS: In this limited series, embolization with NBCA was found to be a safe, feasible, and effective treatment for gastroduodenal arterial bleeding when endoscopic hemostasis had failed.

A new flow control technique using diluted epinephrine in the N-butyl-2-cyanoacrylate embolization of visceral artery pseudoaneurysms secondary to chronic pancreatitis.

Although n-butyl-2-cyanoacrylate (NBCA) has been used as an effective liquid embolization material, its indication for pseudoaneurysms has seemingly been limited because of the technical difficulties of using NBCA, such as reflux to the parent artery and causing significant infarction. Thus, considerable skill in using NBCA or a device to control blood flow during its polymerization is required to achieve embolization without severe complications. We report our new technique for controlling blood flow using diluted epinephrine in transcatheter arterial NBCA embolization of five pseudoaneurysms in four cases secondary to hemosuccus pancreaticus.

Endovascular stenting for left subclavian venous stenosis for a hemodialysis patient with a persistent left superior vena cava.

A persistent left superior vena cava (PLSVC) is the most common thoracic venous anomaly, and we should be aware of its existence. We encountered a case of significant left arm swelling due to recurrent left subclavian venous stenosis in a hemodialysis patient with a PLSVC. Endovascular stent placement was performed safely and effectively for the stenosis employing the pull-through technique, in which a guidewire was passed from the left internal jugular vein to the access vein. On the following day, left arm swelling had improved. 3 months after stent placement the left arm swelling has not recurred.

CT-guided percutaneous drainage within intervertebral space for pyogenic spondylodiscitis with psoas abscess.

BACKGROUND: Reports on CT-guided percutaneous drainage within the intervertebral space for pyogenic spondylodiscitis with a secondary psoas abscess are limited. PURPOSE: To evaluate CT-guided percutaneous drainage within the intervertebral space for pyogenic spondylodiscitis and a secondary psoas abscess in which the two sites appear to communicate. MATERIAL AND METHODS: Eight patients with pyogenic spondylodiscitis and a secondary psoas abscess showing communication with the intradiscal abscess underwent CT-guided percutaneous drainage within the intervertebral space. The clinical outcome was retrospectively assessed. RESULTS: An 8-French pigtail catheter within the intervertebral space was successfully placed in all patients. Seven patients responded well to this treatment. The one remaining patient who had developed septic shock before the procedure died on the following day. The mean duration of drainage was 32 days (13-70 days). Only one patient with persistent back pain underwent surgery for stabilization of the spine after the improvement of inflammation. Among seven patients responding well, long-term follow-up (91-801 days, mean 292 days) was conducted in six patients excluding one patient who died of asphyxiation due to aspiration unrelated to the procedure within 30 days after the procedure. In these six patients, no recurrence of either pyogenic spondylodiscitis or the psoas abscess was noted. CONCLUSION: CT-guided percutaneous drainage within the intervertebral space can be effective for patients with pyogenic spondylodiscitis and a secondary psoas abscess if the psoas abscess communicates with the intradiscal abscess.

Transcatheter arterial embolization for spontaneous rupture of the omental artery.

We encountered a rare case of spontaneous rupture of the omental artery. A 25-year-old man without any episode of abdominal trauma or bleeding disorders came to the emergency unit with left upper abdominal pain. Hematoma with extravasation of the greater omentum and a hemoperitoneum was confirmed on abdominal contrast-enhanced computed tomography. Bleeding from the omental artery was suspected based on these findings. Transcatheter arterial embolization was successfully performed after extravasation of the omental artery, which arises from the left gastroepiploic artery, was confirmed on arteriography. Partial ometectomy was performed 10 days after transcatheter arterial embolization, revealing that the hematoma measured 10 cm in diameter in the greater omentum. Pathological examination showed rupture of the branch of an omental artery without abnormal findings, such as an aneurysm or neoplasm. Thus, we diagnosed him with spontaneous rupture of the omental artery. The patient recovered and was discharged from the hospital 10 days after the surgery, with a favorable postoperative course.