Investigation of the Characteristics of New, Uniform, Extremely Small Iron-Based Nanoparticles as T1 Contrast Agents for MRI

Objective@#The purpose of this study was to evaluate the magnetic resonance (MR) characteristics and applicability of new, uniform, extremely small iron-based nanoparticles (ESIONs) with 3–4-nm iron cores using contrast-enhanced magnetic resonance angiography (MRA). @*Materials and Methods@#Seven types of ESIONs were used in phantom and animal experiments with 1.5T, 3T, and 4.7T scanners. The MR characteristics of the ESIONs were evaluated via phantom experiments. With the ESIONs selected by the phantom experiments, animal experiments were performed on eight rabbits. In the animal experiments, the in vivo kinetics and enhancement effect of the ESIONs were evaluated using half-diluted and non-diluted ESIONs. The between-group differences were assessed using a linear mixed model. A commercially available gadolinium-based contrast agent (GBCA) was used as a control. @*Results@#All ESIONs showed a good T1 shortening effect and were applicable for MRA at 1.5T and 3T. The relaxivity ratio of the ESIONs increased with increasing magnetic field strength. In the animal experiments, the ESIONs showed peak signal intensity on the first-pass images and persistent vascular enhancement until 90 minutes. On the 1-week follow-up images, the ESIONs were nearly washed out from the vascular structures and organs. The peak signal intensity on the first-pass images showed no significant difference between the non-diluted ESIONs with 3-mm iron cores and GBCA (p = 1.000). On the 10-minutes post-contrast images, the non-diluted ESIONs showed a significantly higher signal intensity than did the GBCA (p < 0.001). @*Conclusion@#In the phantom experiments, the ESIONs with 3–4-nm iron oxide cores showed a good T1 shortening effect at 1.5T and 3T. In the animal experiments, the ESIONs with 3-nm iron cores showed comparable enhancement on the first-pass images and superior enhancement effect on the delayed images compared to the commercially available GBCA at 3T.

Investigation of the Characteristics of New, Uniform, Extremely Small Iron-Based Nanoparticles as T1 Contrast Agents for MRI

Objective@#The purpose of this study was to evaluate the magnetic resonance (MR) characteristics and applicability of new, uniform, extremely small iron-based nanoparticles (ESIONs) with 3–4-nm iron cores using contrast-enhanced magnetic resonance angiography (MRA). @*Materials and Methods@#Seven types of ESIONs were used in phantom and animal experiments with 1.5T, 3T, and 4.7T scanners. The MR characteristics of the ESIONs were evaluated via phantom experiments. With the ESIONs selected by the phantom experiments, animal experiments were performed on eight rabbits. In the animal experiments, the in vivo kinetics and enhancement effect of the ESIONs were evaluated using half-diluted and non-diluted ESIONs. The between-group differences were assessed using a linear mixed model. A commercially available gadolinium-based contrast agent (GBCA) was used as a control. @*Results@#All ESIONs showed a good T1 shortening effect and were applicable for MRA at 1.5T and 3T. The relaxivity ratio of the ESIONs increased with increasing magnetic field strength. In the animal experiments, the ESIONs showed peak signal intensity on the first-pass images and persistent vascular enhancement until 90 minutes. On the 1-week follow-up images, the ESIONs were nearly washed out from the vascular structures and organs. The peak signal intensity on the first-pass images showed no significant difference between the non-diluted ESIONs with 3-mm iron cores and GBCA (p = 1.000). On the 10-minutes post-contrast images, the non-diluted ESIONs showed a significantly higher signal intensity than did the GBCA (p < 0.001). @*Conclusion@#In the phantom experiments, the ESIONs with 3–4-nm iron oxide cores showed a good T1 shortening effect at 1.5T and 3T. In the animal experiments, the ESIONs with 3-nm iron cores showed comparable enhancement on the first-pass images and superior enhancement effect on the delayed images compared to the commercially available GBCA at 3T.

Percutaneous Thrombectomy with a Half-Deployed Stent for the Treatment of Acute Inferior Vena Cava Thrombosis

Inferior vena cava (IVC) thrombosis, a type of deep vein thrombosis (DVT), is a relatively rare and poorly known disease compared to lower extremity DVT. We present a case of a 68-year-old woman with abdominal pain and mild lower leg swelling due to IVC thrombosis extending from the common iliac vein to the infrahepatic IVC. The thrombus was removed using a 14-mm Niti-S stent (Taewoong Medical, Korea) inserted via the right internal jugular vein. The stent was partially deployed and gently advanced to cover the thrombus, and then retracted through a vascular sheath capturing the thrombus. This case presents a therapeutic approach for the treatment of IVC thrombosis using a half-deployed stent as a filter and a basket. Follow-up evaluation after 5 years revealed a patent IVC and common iliac vein.

Uterine Artery Embolization in Patients with Postpartum Hemorrhage: Clinical Efficacy and Safety of Treatment with N-Butyl-2-Cyanoacrylate

PURPOSE@#To evaluate the clinical efficacy and safety of uterine artery embolization (UAE) using N-butyl-2-cyanoacrylate (NBCA) in patients with postpartum hemorrhage (PPH).@*MATERIALS AND METHODS@#From February 2010 to May 2018, 14 patients (age: 28–39 years; mean: 33 years) underwent UAE using NBCA among 82 patients with PPH. Medical records were retrospectively reviewed to evaluate the patients characteristics, cause of PPH, embolization procedure, and outcomes.@*RESULTS@#Angiograms revealed extravasation (n = 10) or pseudoaneurysm (n = 4) in all patients. The causes of PPH were hysterotomy or hysterectomy related arterial injury (n = 11), cervical laceration (n = 2), and abnormal placentation (n = 1). UAE was performed with NBCA in all patients. Additional UAE with gelatin sponge particles was performed in two patients. Additional non-uterine artery embolization was performed in three patients. Coagulopathy was found in five (35.7%) patients. The technical and clinical success rates were 92.9% and 85.7%, respectively. One patient died from multi-organ failure eight days after UAE. One patient with abnormal placentation had pelvic organ ischemia due to multiple pelvic artery embolization.@*CONCLUSION@#UAE using NBCA is safe and effective for the patients with PPH showing extravasation or pseudoaneurysm.

Endovascular Recanalization of a Thrombosed Native Arteriovenous Fistula Complicated with an Aneurysm: Technical Aspects and Outcomes

OBJECTIVE: To evaluate the technical aspects and outcomes of endovascular recanalization of a thrombosed native arteriovenous fistula (AVF) complicated with an aneurysm. MATERIALS AND METHODS: Sixteen patients who had a thrombosed AVF complicated with an aneurysm (two radiocephalic and 14 brachiocephalic) were included in this study. Recanalization procedures were performed by mechanical thrombectomy using the Arrow-Trerotola percutaneous thrombectomy device and adjunctive treatments. We evaluated dose of thrombolytic agent, underlying stenosis, procedure time, technical and clinical success, and complications. The primary and secondary patency rates were calculated using the Kaplan-Meier analysis. RESULTS: The thrombolytic agents used were 100000 U urokinase mixed with 500 IU heparin (n = 10) or a double dose of the mixture (n = 6). The thrombi in aneurysms were removed in all but two patients with non-flow limiting residual thrombi. One recanalization failure occurred due to a device failure. Aspiration thrombectomy was performed in 87.5% of cases (n = 14). Underlying stenoses were found in the outflow draining vein (n = 16), arteriovenous anastomosis or juxtaanastomosis area (n = 5), and the central vein (n = 3). Balloon angioplasty was performed for all stenoses in 15 patients. Two patients with a symptomatic central vein stenosis underwent insertion of a stent after balloon angioplasty. Mean procedure time was 116.3 minutes. Minor extravasation (n = 1) was resolved by manual compression. Both technical and clinical success rates were 93.8% (n = 15). The primary patency rates at 3, 6, and 12 months were 70.5%, 54.8%, and 31.3%, respectively. The secondary patency rates at 3, 6, and 12 months were 70.5%, 70.5%, and 47.0%, respectively. CONCLUSION: Thrombosed AVF complicated with an aneurysm can be successfully recanalized, and secondary patency can be prolonged with endovascular treatment.

A case of vulvar hematoma with rupture of pseudoaneurysm of pudendal artery

Vulvar hematomas are uncommon outside of the obstetric population and may be the result of trauma to the perineum. Vulvar hematomas most often present with low abdominal pain and urologic and neurologic symptoms. The vulva has rich vascularization that is supplied by the pudendal artery, a branch of the anterior division of the internal iliac artery. We describe a rare case of a 15-cm-sized vulvar hematoma with the suggested rupture of a pseudoaneurysm of the left pudendal artery without trauma injury. A 14-year-old girl presented with sudden pain and swelling in her left labium and was successfully treated with selective arterial embolization and surgical evacuation. We provide a literature review and discuss patient treatment and management strategies.

Tissue Responses to Stent Grafts with Endo-Exo-Skeleton for Saccular Abdominal Aortic Aneurysms in a Canine Model

OBJECTIVE: We evaluated the effect of close contact between the stent and the graft on the induction of endothelial covering on the stent graft placed over an aneurysm. MATERIALS AND METHODS: Saccular abdominal aortic aneurysms were made with Dacron patch in eight dogs. The stent graft consisted of an inner stent, a expanded polytetrafluoroethylene graft, and an outer stent. After sacrificing the animals, the aortas with an embedded stent graft were excised. The aortas were inspected grossly and evaluated microscopically. RESULTS: The animals were sacrificed at two (n = 3), six (n = 3), and eight months (n = 2) after endovascular repair. In two dogs, the aortic lumen was occluded at two months after the placement. On gross inspection of specimens from the other six dogs with a patent aortic lumen, stent grafts placed over the normal aortic wall were covered by glossy white neointima, whereas, stent grafts placed over the aneurysmal aortic wall were covered by brownish neointima. On microscopic inspection, stent grafts placed over the normal aortic wall were covered by thin neointima (0.27 +/- 0.05 mm, mean +/- standard deviation) with an endothelial layer, and stent grafts placed over the aneurysmal aortic wall were covered by thick neointima (0.62 +/- 0.17 mm) without any endothelial lining. Transgraft cell migration at the normal aortic wall was more active than that at the aneurysmal aortic wall. CONCLUSION: Close contact between the stent and the graft, which was achieved with stent grafts with endo-exo-skeleton, could not enhance endothelial covering on the stent graft placed over the aneurysms.

Embolization of Multiple Systemic Artery to Pulmonary Artery Fistula with Recurrent Hemoptysis / 결핵및호흡기질환

Herein, we report a case of multiple systemic arteries to pulmonary artery fistulas without any underlying causes, presenting recurrent hemoptysis. Transcatheter embolization was successfully performed several times on multiple systemic feeding arteries. Multiple systemic arteries to pulmonary fistulas can be a source of uncontrolled bleeding, and embolization may be a reasonable therapeutic option to control the bleeding.

Tissue Responses to Endovascular Stent Grafts for Saccular Abdominal Aortic Aneurysms in a Canine Model

We investigated tissue responses to endoskeleton stent grafts for saccular abdominal aortic aneurysms (AAAs) in canines. Saccular AAAs were made with Dacron patch in 8 dogs, and were excluded by endoskeleton stent grafts composed of nitinol stent and expanded polytetrafluoroethylene graft. Animals were sacrificed at 2 months (Group 1; n = 3) or 6 months (Group 2; n = 5) after the placement, respectively. The aortas embedding stent grafts were excised en bloc for gross inspection and sliced at 5 to 8 mm intervals for histopathologic evaluation. Stent grafts were patent in all except a dog showing a thrombotic occlusion in Group 2. In the 7 dogs with patent lumen, the graft overhanging the saccular aneurysm was covered by thick or thin thrombi with no endothelial layer, and the graft over the aortic wall was completely covered by neointima with an endothelial layer. Transgraft cell migration was less active at an aneurysm than at adjacent normal aorta. In conclusion, endoskeleton stent grafts over saccular aneurysms show no endothelial coverage and poor transgraft cell migration in a canine model.

Selective Embolization for Post-Endoscopic Sphincterotomy Bleeding: Technical Aspects and Clinical Efficacy

OBJECTIVE: The objective of this study was to evaluate the technical aspects and clinical efficacy of selective embolization for post-endoscopic sphincterotomy bleeding. MATERIALS AND METHODS: We reviewed the records of 10 patients (3%; M:F = 6:4; mean age, 63.3 years) that underwent selective embolization for post-endoscopic sphincterotomy bleeding among 344 patients who received arteriography for nonvariceal upper gastrointestinal bleeding from 2000 to 2009. We analyzed the endoscopic procedure, onset of bleeding, underlying clinical condition, angiographic findings, interventional procedure, and outcomes in these patients. RESULTS: Among the 12 bleeding branches, primary success of hemostasis was achieved in 10 bleeding branches (83%). Secondary success occurred in two additional bleeding branches (100%) after repeated embolization. In 10 patients, post-endoscopic sphincterotomy bleedings were detected during the endoscopic procedure (n = 2, 20%) or later (n = 8, 80%), and the delay was from one to eight days (mean, 2.9 days; +/- 2.3). Coagulopathy was observed in three patients. Eight patients had a single bleeding branch, whereas two patients had two branches. On the selective arteriography, bleeding branches originated from the posterior pancreaticoduodenal artery (n = 8, 67%) and anterior pancreaticoduodenal artery (n = 4, 33%), respectively. Superselection was achieved in four branches and the embolization was performed with n-butyl cyanoacrylate. The eight branches were embolized by combined use of coil, n-butyl cyanoacrylate, or Gelfoam. After the last embolization, there was no rebleeding or complication related to embolization. CONCLUSION: Selective embolization is technically feasible and an effective procedure for post-endoscopic sphincterotomy bleeding. In addition, the posterior pancreaticoduodenal artery is the main origin of the causative vessels of post-endoscopic sphincterotomy bleeding.

The Influence of Stent Design on Neointimal Hyperplasia of an Aortic Stent Covering the Visceral Arterial Ostia: An Experimental Study in Dogs Using a Self-expandable Nitinol Stent

PURPOSE: To assess the influence of stent design [interlacing (type A) vs. crossing method (type B)] on neointimal hyperplasia using a self-expandable nitinol stent, which crosses the side branches of the abdominal aorta. MATERIALS AND METHODS: In seven mongrel dogs, nitinol stents with type A and B intersections were placed in the abdominal aorta across the main branches: 4 Niti-Ms and 3 Niti-Ds. Two months after the stent placement, a DSA was performed for a stent patency evaluation, followed by the extraction of the aortas. The degree of neointimal formation along the wire was evaluated by calculating the area ratio of intimal hyperplasia (type A vs. B). A Student's t-test was employed to investigate the differences in the neointimal hyperplasia between blood types A and B. RESULTS: The total number of wire intersections overlain at the ostia branch ostia was 23 for type A and 36 for type B. The area ratio of the neointimal hyperplasia, for a given area, was 29.09+/-10.82% (type A) and 13.80+/-6.94% (type B) (p < 0.0001)]. Furthermore, the area ratios of the neointimal hyperplasia per area of stent-wire in the given area were 138.38+/-10.84% (type A), 87.58+/-7.36% (type B) (p = 0.0002). CONCLUSION: In conclusion the interlacing pattern vs. the crossing pattern showed a higher level of neointimal formation than the crossing pattern.

Follow-up CT Evaluation of the Mural Changes in Active Takayasu Arteritis

OBJECTIVE: We wanted to evaluate the mural changes by CT on the follow-up examination of patients with active Takayasu arteritis. MATERIALS AND METHODS: The study included 18 patients, (4 males and 14 females), with active Takayasu arteritis. A total of 44 CT examinations were done during the follow-up period (mean: 55.6 months). At the time of the last follow-up CT, the disease, on the basis of the erythrocyte sedimentation rate (ESR), was found to be inactive in five patients and the disease was active and persistent in 13 patients. The thickness and CT attenuation of the aortic wall on the precontrast, arterial and venous phases were measured on the initial and the follow-up CT examinations. The ratio of the mural attenuation over that of the back muscle on the initial CT was compared with the ratio found on the follow-up CT. RESULTS: The initial CT findings included high density and calcifications of the aortic wall in the precontrast images and a thickened wall with enhancements in the arterial and the venous phases. A low-attenuation ring was demonstrated in the venous phase in 15 patients (83%). On the follow-up evaluation, the mean mural thickness decreased significantly from 4.1 mm to 2.4 mm. The mean mural attenuation ratio in the venous phase decreased significantly from 1.9 to 1.3 (p = 0.001). The low attenuation ring was identified in seven patients (39%) who had only with active, persistent Takayasu arteritis. CONCLUSION: The mural changes demonstrated by the follow-up CT evaluations for the patients with active Takayasu arteritis included a decrease of the mural thickness and enhancement, disappearance of the low-attenuation ring on the venous phase, and an increase of the mural attenuation and calcification on the precontrast phase.

Left Atrial Wall Calcification after Mitral Valve Replacement: CT Findings and Clinical Significance

PURPOSE: To evaluate the CT findings and clinical significance of left atrial wall calcification in patients who had undergone mitral valve replacement. MATERIALS AND METHODS: The unenhanced chest CT scans of 36 consecutive patients who had undergone mitral valve replacement were retrospectively reviewed, and left atrial calcification was found in 15. To determine the clinical significance of this, the CT findings were assessed in terms of the diameter of the left main pulmonary artery, the interval between previous surgery and scanning, and pulmonary arterial pressure. RESULTS: Left atrial wall calcification was either focal (linear, n=7; nodular, n=5), or diffuse (involving at least one-fourth of the left atrial wall) (n=3), and associated left atrial thrombus was found in two patients. Systolic pulmonary arterial pressure was significantly higher in those with calcification than those without (p<0.05), though between these groups there was no significant difference in the diameter of the left main pulmonary artery or the time interval between previous surgery and CT scanning. CONCLUSION: Left atrial wall calcification is a common finding in patients who have undergone mitral valve replacement, particularly in those with high pulmonary arterial pressure.