[en] A new type of proportional flow control valve actuated by a Shape Memory Alloy (SMA) is proposed. After analyzing pressure level on the basis of the governing equation, an appropriate size of the valve system is designed and simulated. The pressure of the valve is to be controlled by controlling the diaphragm which is directly connected to the SMA strip. The response characteristic of the valve is investigated by applying a step input current. Subsequently, position controllably of the cylinder associated with the SMA valve is evaluated by implementing a sliding mode controller

[en] To evaluate the efficacy of the intra-arterial treatment of patients with arterial occlusion by acute thrombus. This retrospective study was performed on 44 patients (28 men; 16 women; mean age -66.6 years; range 32-88 years) seen between January 1, 1999 and July 21, 2006, at the Chonbuk National University Hospital and clinically suspected and angiographically proven to have arterial thrombus. The mean symptom duration was 13.8 days (range; 0-31 days) and the treatment methods included IAUK thrombolysis, catheter aspiration thrombectomy, PTA, and stent insertion. The initial success rate for the different treatment methods was 93%. The success rate of the thrombolysis alone and the combined thrombectomy were 16% and 23%, respectively. Thirty-four patients had remnant stenosis following a thrmobolysis and thrombectomy. As a result, 27 patients were treated with PTA at a 30% success rate. Another 6 patients were treated by stent insertion without PTA at a 100% success rate. Stent insertion adjunct to PTA was successful in 89% of cases. The primary patency rates for 3, 6, and 12 months after treatment were 93%, 89%, and 89%, respectively. The secondary patency rates for 3, 6, and 12 months after treatment were 100%, 100% and, 100%, respectively. Our study suggests that the treatment methods including the intervention of the thrombolysis, thrombus removal, angioplasty, and stent insertion for an acute thrombotic arterial occlusion (single or combined), would all be helpful depending on the status of the disease

[en] To assess the clinical outcomes of the transcatheter microcoil embolization in patients with active lower gastrointestinal (LGI) bleeding in the small bowel, as well as to compare the mortality rates between the two groups based on the visualization or non-visualization of the bleeding focus determined by an angiography. We retrospectively evaluated all of the consecutive patients who underwent an angiography for treatment of acute LGI bleeding between January 2003 and October 2007. In total, the study included 36 patients who underwent a colonoscopy and were diagnosed to have an active bleeding in the LGI tracts. Based on the visualization or non-visualization of the bleeding focus, determined by an angiography, the patients were classified into two groups. The clinical outcomes included technical success, clinical success (no rebleeding within 30 days), delayed rebleeding (> 30 days), as well as the major and minor complication rates. Of the 36 patients, 17 had angiography-proven bleeding that was distal to the marginal artery. The remaining 19 patients did not have a bleeding focus based on the angiography results. The technical and clinical success rates of performing transcatheter microcoil embolizations in patients with active bleeding were 100% and 88%, respectively (15 of 17). One patient died from continued LGI bleeding and one patient received surgery to treat the continued bleeding. There was no note made on the delayed bleeding or on the major or minor complications. Of the 19 patients without active bleeding, 16 (84%) did not have recurrent bleeding. One patient died due to continuous bleeding and multi-organ failure. The superselective microcoil embolization can help successfully treat patients with active LGI bleeding in the small bowel, identified by the results of an angiography. The mortality rate is not significantly different between the patients of the visualization and non-visualization groups on angiography

[en] To evaluate the feasibility and clinical usefulness of three-dimensional contrast-enhanced MR angiography (3D-CE-MRA) as a screening test in the evaluation of pelvic and lower extremity arterial diseases. Forty-four patients who underwent 3D-CE-MRA were included in this study. Coronal 3-dimensional gradient-echo, pre-and post contrast image were acquired with a dedicated peripheral vascular coil and moving-bed technique on a 1.5T MR system. Timing of start of data acquisition was determined by MR fluoroscopy technique, and 0.2 mmol/kg Gd-DTPA was injected into an antecubital vein, at a rate of 1cc/sec with an autoinjector. For quantitative analysis, signal to noise ratio (SNR) and artery to soft tissue contrast to noise ratio (CNR) of lower extremities arterial system including lower abdominal aorta were calculated. For qualitative analysis, arterial systems were divided into six segments, and were evaluated in terms of conspicuity of arterial systems and the degree of venous enhancement by three- and four-point scale respectively. In eight patients who underwent both MR angiography and conventional angiography as standard reference. Imaging analysis was done by means of consensus between two experienced radiologists. The mean time for the examination was about 15 min (± 5 min). The mean SNR of arterial system was 26.5±11.6, and mean artery to soft tissue contrast to noise ratio (CNR) was 24.6±11.2. Among the total 525 arterial segments 498 arterial segments (94.5%) could be demonstrated with good delineation of entire arterial tree. Good arterial imaging without or with minimal venous enhancement were demonstrated in 98.5% (260/264) in above knee and 89% (211/261) in below knee (p<0.01). Ten of 525 segments (1.9%) demonstrated severe venous overlapping and it mostly occurred in the calf region. In comparison with DSA, the sensitivity and the specificity for MR angiography for the detection of occlusions were 96% and 98.8%, respectively, and for the detection of more than 50% stenosis, 82.2% and 92.9%, respectively. 3D-CE-MRA provided adequate image for the evaluation of the lower extremity artery, and could be used as a screening test for arterial occlusive diseases

[en] This study was deigned to evaluate the technique and clinical efficacy of the use of percutaneous transportal sclerotherapy with N-butyl-2-cyanoacrylate (NBCA) for patients with gastric varices. Seven patients were treated by transportal sclerotherapy with the use of NBCA. For transportal sclerotherapy, portal vein catheterization was performed with a 6-Fr sheath by the transhepatic approach. A 5-Fr catheter was introduced into the afferent gastric vein and a microcatheter was advanced through the 5-Fr catheter into the varices. NBCA was injected through the microcatheter in the varices by use of the continuous single-column injection technique. After the procedure, postcontrast computed tomography (CT) was performed on the next day and then every six months. Gastroendoscopy was performed at one week, three months, and then every six months after the procedure. The technical success rate of the procedure was 88%. In six patients, gastric varices were successfully obliterated with 1-8 mL (mean, 5.4 mL) of a NBCA-Lipiodol mixture injected via a microcatheter. No complications related to the procedure were encountered. As seen on the follow-up endoscopy and CT imaging performed after six months, the presence of gastric varcies was not seen in any of the patients after treatment with the NBCA-Lipiodol mixture and the use of microcoils. Recurrence of gastric varices was not observed during the followup period. Worsening of esophageal varices occurred in four patients after transportal sclerotherapy. The serum albumin level increased, the ammonia level decreased and the prothrombin time increased at six months after the procedure (p < 0.05). Percutaneous transportal sclerotherapy with NBCA is useful to obliterate gastric varices if it is not possible to perform balloon-occluded retrograde transvenous obliteration

[en] This study was designed to evaluate the usefulness of transcatheter arterial embolization (TAE) in hemodynamically unstable patients with a pelvic bone fracture. From November 2004 to July 2007, we retrospectively reviewed 211 patients with pelvic bone fractures. Of these patients, 24 patients with CT findings of active bleeding or hemodynamic instability underwent pelvic angiography. There were 13 female and 11 male patients, with an age range from 21 to 92 years (mean age, 58.3 years). To evaluate arterial injuries, angiography was performed, followed by TAE using coils, gelfoams and N-butyl-2-cyanoacrylate. The evaluation of risk factors between patients who were still alive and patients who had expired was performed statistically by use of the Student's t test and chisquared analysis. A total of 28 TAE procedures were performed in 24 patients and 50 injured arteries were occluded. Six patients (25%) died due to hypovolemic shock within 47 hours. Five of the patients were hemodynamically unstable (BP below 76/56 mmHg) prior to the angiographic procedure and one patient had a pseudoaneurysm located at the superior mesenteric artery. Dopamine usage and blood pressure before the procedure for patients showed a statistically significant difference between patients were still alive and patients who had expired (p = 0.01, p = 0.001). TAE is a safe and effective treatment for an arterial injury of a pelvic bone fracture. The outcome of patients with a hemodynamically unstable state before TAE is poor

[en] The studies have shown that crystalline ceramics are better hosts compared to glass matrix due to their superior chemical durability and higher density. Synroc, atitanate based ceramic containing hollandite, perovskite, zirconolite and rutile phases, is considered as the most effective and durable means of immobilizing various forms of high-level radioactive wastes for disposal. The oxide-route (solid state reaction) is the most known process to form a solid solution. However, the synthesis of nano crystalline powders using an exothermic redox reaction between nitrate and organics in an aqueous solution has been reported. In this study, the SCS and oxide route was compared to form the solid solution of Synroc-B nano crystalline powders. TEM mapping results on combustion synthesized powder has been confirmed that it contains the fully solid solution occurred on constituent elements for the composition Synroc-B in all powders. TEM analyses also show that particle size is very homogeneous and evenly distributed in 20257-258⁓30 nm. By a combustion synthesis method Synroc-B nano powder of a multi-phase is could be produced in a relatively easy way. Solidified in the Synroc-B complex, radioactive elements contained in waste can easily be immobilized

[en] AIM: To evaluate the feasibility and safety of fluoroscopic-guided covered metallic stent placements in providing palliative care for patients with inoperable malignant gastric outlet obstruction. MATERIALS AND METHODS: Under fluoroscopic guidance, placement of self-expandable, covered stents was attempted in 20 patients with inoperable or recurrent gastric cancer (age range 36-79 years). All patients had inoperable gastric outlet obstruction, 13 with native anatomy and seven with post-operative anatomy (gastrointestinal anastomotic sites). All patients had intolerance to oral alimentation and/or vomiting after ingestion. Success was defined both technically and clinically. RESULTS: The placement of the stent was technically successful in 18 patients and failed in two patients (technical success: 90%). The cause of the technical failures was an inability to negotiate the guide wire through the obstruction sites in spite of the use of both fluoroscopic and endoscopic guidance. After stent placement, 15 patients were able to ingest at least liquids and had a markedly decreased incidence of vomiting (clinical success: 75%). During the mean follow-up of 6 weeks, there have been no stent reocclusion and no life-threatening complications except migration of two stents in one patient. CONCLUSION: Fluoroscopically guided covered metallic stent placement appears to be valuable for the palliative treatment of malignant obstruction of gastric outlet and post-operative gastrointestinal anastomoses. Lee, J.M. et al. (2001)

[en] To evaluate the differential findings of CT in the differention of pleural exudates and transudates. One hundred and thirteen consecutive patients (113 effusions) underwent enhanced thoracic CT ; the scans were evaluated for the presence or absence and apearance of enhancing parietal pleural thickening and extrapleural fat thickening. Thoracentesis was performed to measure pleural and serum total protein and lactate dehydrogenase(LDH) values. Effusions were classified as exudates by using Light's criteria. Eighty-eight effusions were exudates and 25 were transudates. Eighty-three of the 88 exudates (93 %) were associated with enhanced parietal pleural thickening;seventy of the 88 (80%) were associated with extrapleural fat thickening. Four of the 25 transudates were associated with parietal pleural thickening and extrapleural fat thickening, both of which were the most important factors in differentiating between pleural exudates and transudates(p<0.05). Parietal pleural thickening and extrapleural fat thickening on contrast-enhanced CT almost always indicate the presence of pleural exudates

[en] A 43-years-old man was admitted complaining of swallowing difficulties. The esophagography revealed severe stenosis at the esophagogastric anastomotic site. Esophagography after balloon dilatation showed a transmural perforation with mediastinal leakage. The patient was treated conservatively for one week at which time the esophagography showed no further leakage at the anastomotic site and the good passage of barium. A 2-year follow-up chest computed tomography (CT) showed good patency of the esophageal lumen and the marked resorption of barium in the mediastinum