Hyung Jin Shim

Tuberculous Aneurysm of the Abdominal Aorta: Endovascular Repair Using Stent Grafts in Two Cases

Tuberculous aneurysm of the aorta is exceedingly rare. To date, the standard therapy for mycotic aneurysm of the abdominal aorta has been surgery involving in-situ graft placement or extra-anatomic bypass surgery followed by effective anti-tuberculous medication. Only recently has the use of a stent graft in the treatment of tuberculous aortic aneurysm been described in the literature. We report two cases in which a tuberculous aneurysm of the abdominal aorta was successfully repaired using endovascular stent grafts. One case involved is a 42-year-old woman with a large suprarenal abdominal aortic aneurysm and a right psoas abscess, and the other, a 41-year-old man in whom an abdominal aortic aneurysm ruptured during surgical drainage of a psoas abscess.

In vivo Tracking of Mesenchymal Stem Cells Labeled with a Novel Chitosan-coated Superparamagnetic Iron Oxide Nanoparticles using 3.0T MRI

This study aimed to characterize and MRI track the mesenchymal stem cells labeled with chitosan-coated superparamagnetic iron oxide (Chitosan-SPIO). Chitosan-SPIO was synthesized from a mixture of FeCl2 and FeCl3. The human bone marrow derived mesenchymal stem cells (hBM-MSC) were labeled with 50 µg Fe/mL chitosan-SPIO and Resovist. The labeling efficiency was assessed by iron content, Prussian blue staining, electron microscopy and in vitro MR imaging. The labeled cells were also analyzed for cytotoxicity, phenotype and differentiation potential. Electron microscopic observations and Prussian blue staining revealed 100% of cells were labeled with iron particles. MR imaging was able to detect the labeled MSC successfully. Chitosan-SPIO did not show any cytotoxicity up to 200 µg Fe/mL concentration. The labeled stem cells did not exhibit any significant alterations in the surface markers expression or adipo/osteo/chondrogenic differentiation potential when compared to unlabeled control cells. After contralateral injection into rabbit ischemic brain, the iron labeled stem cells were tracked by periodical in vivo MR images. The migration of cells was also confirmed by histological studies. The novel chitosan-SPIO enables to label and track MSC for in vivo MRI without cellular alteration.

Hepatocellular carcinoma: correlation between vascular endothelial growth factor level and degree of enhancement by multiphase contrast-enhanced computed tomography.

Kwak BK, Shim HJ, Park ES, et al. Hepatocellular carcinoma: Correlation between vascular endothelial growth factor level and degree of enhancement by multiphase contrast-enhanced computed tomography. Invest Radiol 2001;36:487–492. rationale and objectives. To determine whether vascular endothelial growth factor (VEGF) is a histopathological factor influencing contrast enhancement of hepatocellular carcinoma (HCC) on computed tomography (CT). methods.Twenty-two nodular HCCs underwent multiphase helical CT and surgery. Tumor size, histological grading of differentiation, and type of hepatitis were evaluated. Tumor attenuation was graded as hyperattenuated, isoattenuated, and hypoattenuated. Immunohistochemical staining with anti-VEGF antibody was performed and scored as weak, intermediate, or strong. Spearman’s rank correlation test was used. results.Tumors ranged from 1.0 to 12.0 cm (mean 5.1 cm). The degree of enhancement during the hepatic arterial phase was significantly correlated with VEGF expression. Size was negatively correlated with VEGF expression and the degree of enhancement, but histological grade and type of hepatitis were not correlated with VEGF expression, tumor size, or degree of enhancement. conclusions.In HCC, VEGF expression is correlated with the degree of contrast enhancement during arterial-phase CT.

Functional characterization of mesenchymal stem cells labeled with a novel PVP-coated superparamagnetic iron oxide.

Magnetic resonance imaging of cells labeled with superparamagnetic iron oxide (SPIO) could be a valuable tool for tracking transplanted cells in living organisms. Human bone marrow-derived mesenchymal stem cells (hBMMSC) were labeled with a novel polyvinyl pyrrolidone (PVP)-coated SPIO. Prussian blue staining and electron microscopy revealed that almost all of the cells were efficiently labeled with PVP-SPIO nanoparticles. There were no signs of cytotoxicity, even at concentrations of up to 1600 microg Fe/ml of the nanoparticles, and the labeled cells were successfully visualized by in vitro cellular MRI. In addition, there was no significant alteration of the phenotype or the adipo/osteo/chondrogenic differentiation potential of the cells. This was in contrast to Feridex IV labeling that led to the inhibition of hBMMSC chondrogenesis. Following intramuscular injection in a rabbit hind limb ischemia model, the intercellular migration of the labeled cells toward the ablated site was clearly tracked through in vivo MRI. The localization of the transplanted cells observed by MRI correlated well with postmortem histological studies. These results demonstrate that the novel PVP-SPIO nanoparticles appear to be efficient MR contrast agents and may enable non-invasive in vivo tracking of stem cells in experimental and clinical settings during cell therapy.

Retrievable Biliary Stent-Graft in the Treatment of Benign Biliary Strictures

PURPOSE To investigate the technical and clinical efficacy of a retrievable stent-graft in the treatment of benign biliary strictures. MATERIALS AND METHODS From February 2004 to December 2006, 29 patients with 32 benign biliary strictures (17 patients with 18 chronic cholangitis strictures and 12 with 14 postoperative strictures) were enrolled in this study. Twenty-four patients had 26 recurrent strictures despite prolonged catheter interposition after balloon dilation procedures. Five patients with six strictures had not previously undergone interventional treatment. A total of 36 stent-grafts were placed, and all stent-grafts were removed by means of a percutaneous route or via a T-tube 6.7 weeks (range, 2-10 weeks) after stent-graft placement. RESULTS The retrievable stent-grafts were successfully placed and removed in all cases. Migration occurred in four of the 36 (11%) stent-grafts (11%). Immediately after stent-graft removal, all strictures were widened significantly. From 2 days to 8 weeks after removal, 29 of 32 lesions (91%) remained patent with or without recurrence of minimal strictures. During the mean follow-up of 27.9 months (range, 9-34 months), none of the 29 lesions had recurrence of clinically significant strictures. The primary patency rate was 90.6%. Three additional stent-graft placements for recurrent stricture were required in three lesions (9.4%). During a mean follow-up of 13.3 months (range, 9-16 months), two patients had no evidence of biliary obstruction. The secondary patency rate and clinical success rate was 97% (31 of 32 lesions). CONCLUSIONS The placement and removal of a retrievable stent-graft in the treatment of benign biliary strictures is technically feasible and appears to be a clinically effective method.

Preparation of doxorubicin-containing chitosan microspheres for transcatheter arterial chemoembolization of hepatocellular carcinoma

A new form of doxorubicin hydrochloride (DRH)-containing chitosan microspheres (CMs) was prepared by employing an expanding-loading-shrinking (E-L-S) process. One hundred mg of pre-formed CMs were soaked in absolute ethanol and then placed in reduced pressure (the expanding process). Ten mg of DRH (2 mg ml−1) were added into the expanded CMs (the loading process). Next the microspheres were freeze-dried (the shrinking process). As a result of this E-L-S process, 10% (w/w) DRH-containing CMs (DRH-CM) were made. During 7 days, 22.6% of the DRH was observed to be released on the in vitro drug release study. In addition, these new DRH-CMs could be used for transcatheter arterial chemoembolization (TACE) procedure in VX2 hepatic tumour models of rabbit and the anti-tumour effects of DRH-CMs were investigated. On the post-CT scan 7 days after the TACE, total infarctions of the VX2 tumour were observed in 5 rabbits among the 6 total rabbits.

Endovascular treatment for common iliac artery injury complicating lumbar disc surgery : limited usefulness of temporary balloon occlusion.

Vascular injury during lumbar disc surgery is a rare but potentially life-threatening complication. It has been managed by open vascular surgical repair. With recent technologic advance, endovascular treatment became one of effective treatment modalities. We present a case of a 32-year-old woman who suffered with common iliac artery injury during lumbar disc surgery that was treated successfully by endovascular repair with temporary balloon occlusion and subsequent insertion of a covered stent. Temporary balloon occlusion for 1.5 hours could stop bleeding, but growing pseudoaneurysm was identified at the injury site during the following 13 days. It seems that the temporary balloon occlusion can stall bleeding from arterial injury for considerable time duration, but cannot be a single treatment modality and requires subsequent insertion of a covered stent.

MRI traceability of superparamagnetic iron oxide nanoparticle-embedded chitosan microspheres as an embolic material in rabbit uterus

PURPOSE We aimed to compare polyvinyl alcohol (PVA) particles with calibrated superparamagnetic iron oxide (SPIO) nanoparticle-loaded chitosan microspheres in a rabbit model, specifically regarding the relative distribution of embolic agents within the uterus based on magnetic resonance imaging (MRI) and pathological evaluation. METHODS Twelve New Zealand white rabbits underwent uterine artery embolization using either standard PVA particles (45-150 µm or 350-500 µm) or calibrated SPIO-embedded chitosan microspheres (45-150 µm or 300-500 µm). MRI and histopathological findings were compared one week after embolization. RESULTS Calibrated SPIO-loaded chitosan microspheres 45-150 µm in size were detected on T2-weighted images. On histological analysis, calibrated SPIO-embedded chitosan microspheres were found in both myometrium and endometrium, whereas PVA particles were found only in the perimyometrium or extrauterine fat pads. A proportional relationship was noted between the calibrated SPIO-embedded chitosan microsphere size and the size of the occluded artery. CONCLUSION Calibrated SPIO-embedded chitosan microspheres induced greater segmental arterial occlusion than PVA particles and showed great potential as a new embolic material. SPIO-embedded chitosan microspheres can be used to follow distribution of embolic particles through MRI studies.

Fixation methods for implantable port chamber: comparative study using glue, self-stabilizing leg and suture fixations in rabbits.

Objective To evaluate the fixation strength and tissue reaction of the glue fixation and self-stabilizing leg fixation methods and to compare the results with those of the conventional tagging suture fixation method. Materials and Methods Twelve healthy rabbits were selected and three different methods of implanting the port chamber were employed on the back of each rabbit. A total of thirty six port chambers were implanted with these three different methods, viz. the glue fixation method using tissue adhesive, the self-stabilizing leg method using a self-expandable stabilizing leg, and the suture fixation method. The fixation strength and the gross and histopathologic changes of each fixation method were evaluated at three days, one week, two weeks and four weeks after port implantation. Results The glue fixation method showed a good fixation strength, which was similar to that of the tagging suture method (p = 0.3486). Five of the six ports (83%) implanted with the glue fixation method which were examined after two weeks showed cracks on the external surface, but this had no adverse effects on their function. A large amount of granulation tissue reaction was found at the bottom of the chamber (p = 0.0025). The fixation with the self-stabilizing leg showed relatively lower fixation strength (p = 0.0043), but no turning-over of the chamber occurred. The fixation strength improved with time after the first week, and minimal granulation tissue reaction was observed with this method. Conclusion The glue fixation method exhibited equal fixation strength compared to the suture fixation, but showed cracking and a large amount of granulation tissue, whereas the fixation with a self-stabilizing leg showed weaker fixation strength.

Arterial Occlusion Using a Microguidewire as a Radiofrequency Electrode

Purpose: To illustrate the use of superselective radiofrequency (RF) energy delivery for arterial occlusion in vessels requiring embolization. Technique: A 3.0-F microcatheter and a 0.016-inch stainless steel microguidewire coated with polytetrafluoroethylene except for the floppy platinum-coiled tip are inserted into the diseased arteries. After positioning the microcatheter at the target site, the floppy tip of the microguidewire is advanced 1 to 2 cm beyond the microcatheter to act as an electrode. RF ablation is performed at a power of 20 watts until there was a rise in uncontrolled impedance. If occlusion is incomplete, embolic agents can be applied. The use of the technique is illustrated in 4 cases, 3 involving renal branch arteries and a large arteriovenous malformation in the buttock. RF energy was successful in occluding the target vessels in 3 cases; the other required additional embolization. There were no complications, and the patients had sustained occlusion of the lesions. Conclusion: Diseased arteries can be endovascularly occluded using a microguidewire to deliver radiofrequency energy. However, further development of the technique is needed to circumvent wire adhesion to the arterial wall and optimize RF delivery to avoid damage to adjacent structures.