Biomedical subjects

Chang Jin Yoon

Publications and source records attributed to Chang Jin Yoon.

At least 19 recordsLinked to original sources

PubMed2006

Malignant duodenal obstructions: palliative treatment using self-expandable nitinol stents.

PURPOSE: To assess the efficacy of fluoroscopic per oral placement of self-expandable nitinol stents in the palliative treatment of malignant duodenal obstructions. MATERIALS AND METHODS: Under fluoroscopic guidance, 82 patients (56 male and 26 female; mean age, 62.3 y) with malignant duodenal obstructions were treated with per oral placement of four types of self-expandable nitinol stents. All patients presented with severe nausea and recurrent vomiting, and their obstructions were inoperable. RESULTS: Technical success was achieved in 78 of 82 patients (95.1%). After stent placement, food intake capacity improved in 74 of 78 patients (94.9%). Stent migration occurred in one patient 4 days after placement. A covered stent was placed to cover the ampulla of Vater in 15 patients without external biliary drainage; three of them (20%) became jaundiced. During the mean follow-up period of 74.7 days (range, 9-374 d), eight patients developed recurrent obstructive symptoms caused by tumor ingrowth (n=2) or tumor overgrowth (n=6). They were successfully treated by additional stent placement. The primary stent patency rates were 97.0%, 79.8%, and 44.0% at 30-, 90-, and 180 days, respectively (mean patency, 228.2 d; 95% CI, 153.9-302.5). CONCLUSIONS: Fluoroscopic per oral placement of self-expandable nitinol stents is an effective palliative treatment for malignant duodenal obstructions.

Adult↗

PubMed2006

Covered retrievable prostatic urethral stents: feasibility study in a canine model.

PURPOSE: To evaluate the feasibility of use of a covered, retrievable prostatic urethral stent and to determine urethrographic and histologic changes in the prostate induced by the stent in a canine model. MATERIALS AND METHODS: Polytetrafluoroethylene-covered retrievable nitinol stents were placed in the normal prostatic urethras of 13 dogs. The stents were removed 8 weeks after placement. The dogs were killed immediately after stent removal (group 1, n = 5) or 8 weeks after stent removal (group 2, n = 8). Retrograde urethrograms were obtained every 2 weeks after stent placement and after stent removal in dogs that had not been killed. The histologic changes in the prostate were compared between the two groups. RESULTS: Stent placement was technically successful in all dogs. In two dogs, a second stent was placed because of migration of the first stent into the urinary bladder. Stent removal was successful in 12 dogs. One stent was removed in its expanded state. On follow-up urethrograms, dilation of the prostatic urethra persisted until animals were killed (P = .14). The mucosal hyperplasia that occurred after stent placement at both ends of the stent gradually decreased after stent removal (P < .001). Histologic examination revealed prostate glandular atrophy and periurethral fibrosis, which did not differ between the two groups (P = .72 and P = .83, respectively). Papillary hyperplasia of the uroepithelium and submucosal inflammatory cell infiltration was decreased significantly in group 2 compared with group 1 (P = .002, P = .011, respectively). CONCLUSIONS: Covered retrievable prostatic urethral stents seem to be feasible for use in the canine prostatic urethra. The stent-induced prostatic urethral dilation and prostate glandular atrophy persist until 8 weeks after stent removal.

Animals↗

PubMed2006

Bronchial catheterization with a TIPS dilator after failure of conventional technique.

OBJECTIVE: A technique is presented for catheterization of an obstructed bronchus when use of a conventional vascular catheter has failed. In some cases, strictures become too stenotic or blunt for passage of a guidewire, making further intervention impossible. We attempted to negotiate a stricture opening using a transjugular intrahepatic portosystemic shunt (TIPS) dilator with a guidewire inside it. CONCLUSION: The catheterization technique with a TIPS dilator was successful in nine cases in which use of conventional catheters and guidewires had failed.

Adult↗

PubMed2005

Use of guiding sheaths in peroral fluoroscopic gastroduodenal stent placement.

Our purpose was to assess the safety and usefulness of guiding sheaths in peroral fluoroscopic gastroduodenal stent placement. Two types of guiding sheath were made from straight polytetrafluoroethylene tubes. Type A was 80 cm in length, 4 mm in outer diameter and 3 mm in inner diameter. Type B was 70 cm in length, 6 mm in outer diameter and 5 mm in inner diameter. The type A sheath was used in 18 patients in whom a catheter-guide wire combination failed to pass through a stricture. The type B sheath was used in 22 patients in whom a stent delivery system failed to pass through the stricture due to loop formation within the gastric lumen. The overall success rate for guiding a catheter-guide wire through a stricture after using the type A sheath was 89%. The overall success rate for passing a stent delivery system through a stricture after using the type B sheath was 100%. All procedures were tolerated by the patients without any significant complications. The guiding sheaths were safe and useful in peroral fluoroscopic gastroduodenal stent placement.

Aged↗

PubMed2005

Tissue hyperplasia: influence of a paclitaxel-eluting covered stent--preliminary study in a canine urethral model.

PURPOSE: To evaluate a paclitaxel-eluting covered stent in reduction of tissue hyperplasia after stent placement in a canine urethral model. MATERIALS AND METHODS: Procedures were performed in accordance with the National Institutes of Health guidelines for humane handling of animals; approval of the committee of animal research was obtained. Twenty paclitaxel-eluting polyurethane-covered stents (drug stents) and 20 polyurethane-covered stents (control stents) were placed alternately between the proximal and distal urethra in 20 male dogs. The dose of paclitaxel was approximately 1800 mug in each drug stent but absent in each control stent. Dogs were sacrificed either 4 (n = 10) or 8 (n = 10) weeks after stent placement. The percentage diameter of stenosis was assessed with follow-up retrograde urethrography and histologic findings obtained after sacrifice and compared between drug stents and control stents and between the proximal and the distal urethra. RESULTS: Two drug stents partially migrated during retrograde urethrography immediately after stent placement; they were removed and replaced with a second stent during the same procedure. There was a strong tendency toward a lower percentage diameter of stenosis and numeric mean values of the four histologic findings, which indicates less formation of tissue hyperplasia in the proximal urethra than in the distal urethra. In particular, thickness of the papillary projection denoting the entire thickness of hyperplastic reaction was significantly less in drug stents than in control stents in the proximal urethra in the 8-week group (P = .016, Mann-Whitney U test). CONCLUSION: Local delivery of paclitaxel via covered stents has the potential to reduce tissue hyperplasia secondary to stent placement in a canine urethral model. With stent placement, there are distinct differences of tissue hyperplasia between the proximal and distal urethra.

Animals↗

PubMed2005

Transjugular intrahepatic portosystemic shunt for acute variceal bleeding in patients with viral liver cirrhosis: predictors of early mortality.

OBJECTIVE: The purpose of our study was to assess the predictors of early mortality after the creation of transjugular intrahepatic portosystemic shunts (TIPS) for acute variceal bleeding in patients with viral liver cirrhosis. MATERIALS AND METHODS: Seventy-three patients (56 men and 17 women; mean age, 51.3 years) with viral liver cirrhosis who underwent TIPS placement for acute variceal bleeding were studied. Multiple covariates, including demographic, clinical, and biochemical parameters, were included in univariate and multivariate analyses to determine their association with early (30-day) mortality. RESULTS: During the follow-up period (mean, 35 months 3 days), shunt dysfunction occurred in 33 patients (45.2%). Forty-three patients (58.9%) died, and 23 patients (31.5%) died within 30 days of TIPS. Early death was predicted independently by hyperbilirubinemia (> 3 mg/dL; p = 0.004; odds ratio, 10.6) and elevated serum creatinine level (> 1.7 mg/dL; p =0.018; odds ratio, 12.0). CONCLUSION: Hyperbilirubinemia and elevated serum creatinine level are predictive of early mortality after TIPS creation for acute variceal bleeding in patients with viral liver cirrhosis.

Acute Disease↗

PubMed2004

Heparin-coated angiographic catheters: an in vivo comparison of three coating methods with different heparin release profiles.

We evaluated in vivo anti-thrombogenic effects of three different heparin-coated angiographic catheters with different heparin release profiles. Three different types of heparin-coated 5 French angiographic catheters (rapidly-heparin-releasing, slowly-heparin-releasing, and heparin-adherent catheters) were prepared by coating amphiphilic or hydrophobic heparin derivatives in order to regulate heparin elution. After incubation time of 30 minutes in the arteries of dogs, the amount of thrombus deposition, measured as dry weight, was compared in 10 sets of the three heparin-coated catheters and a non-coated catheter used as control. The surface morphology of catheters after their withdrawal was studied by scanning electron microscopy. The amount of thrombus deposition on the non-coated catheter (374.6 +/- 11.6 mg, mean +/- SD) was significantly larger than those on the rapidly-heparin-releasing (52.0 +/- 12.6), slowly-heparin-releasing (70.4 +/- 23.1), and heparin-adherent catheters (103.7 +/- 39.9) ( p < 0.001, each). The thrombus weights in the three heparin-coated catheters were not statistically different. The scanning electron microscopy showed crusts on the catheter surface, which were thickest in the non-coated catheters. We concluded that the thrombus formation inside a catheter is significantly decreased if the catheter is treated with any of the three heparin-coating methods used in this study. The in vivo anti-thrombogenic effects of these coating methods are not significantly different despite their different heparin release profiles.

Angiography↗

PubMed2004

Experimentally induced small-bowel tumor in rabbits: US-guided percutaneous 18-gauge core biopsy.

PURPOSE: To evaluate the safety and diagnostic yield of percutaneous 18-gauge core biopsy for an experimentally induced small-bowel tumor in a rabbit model. MATERIALS AND METHODS: Small-bowel tumors were induced by injecting VX2 tumor into 20 rabbits. After 3 weeks, the small bowel was filled with 100 mL of 2% diluted contrast agent containing methylene blue by using a 5-F catheter. Fifty biopsy firings for small-bowel tumor were performed with ultrasonographic (US) guidance by using an 18-gauge automatic gun. Computed tomography (CT) was performed before and immediately after biopsy. Any procedure-related complications, including leakage of air or fluid, hematoma, and perforation as seen at CT and identified at laparotomy, which was performed 48 hours after biopsy, were evaluated. White blood cell (WBC), red blood cell, and platelet counts; hemoglobin and hematocrit levels; and erythrocyte sedimentation rate were also obtained before and 48 hours after biopsy. Comparison was performed with paired t test. The diagnostic yield was calculated, and the specimen was evaluated whether fragments of mucosa were included or not. RESULTS: No contrast agent leakage or pneumoperitoneum suggesting perforation was identified at CT or laparotomy. Fluid leakage was observed with manual squeezing at two biopsy sites (4%). In two rabbits, hemoperitoneum was observed at CT or laparotomy. Hematoma larger than 3 cm was observed in six rabbits. WBC count and erythrocyte sedimentation rate slightly increased, and red blood cells, hemoglobin, hematocrit, and platelets counts had decreased slightly after biopsy but were not significant (P >.05). Definitive histologic diagnosis of tumor was obtained in 44 (88%) of 50 biopsy sites. Fragments of mucosa were observed in 13 (28%) specimens of 10 rabbits. CONCLUSION: Core biopsies of small-bowel tumor can be performed safely with an 18-gauge gun without severe complications and allow histologic diagnosis of small-bowel tumor with a good diagnostic yield.

Animals↗

PubMed2004

Volumetric tumor measurement using three-dimensional ultrasound: in vitro phantom study on measurement accuracy under various scanning conditions.

Factors influencing volumetric tumor measurement using 3-D ultrasound (US) were investigated. A 3-D US unit equipped with 4- to 8-MHz curved-array and 5- to 10-MHz linear-array mechanical volume transducers, and a US phantom made of 20 ham pieces (8.6 approximately 10.5 mL) embedded in agar gel that simulated hyperechoic tumors, were used. Volumetric tumor measurement was significantly affected by the position of US focus and tumor depth. When focus was at 2 cm and 8 cm below the transducer, 5-cm-deep tumors were measured 5.6% +/- 2.8% (mean +/- SD) and 8.3% +/- 2.2% bigger, respectively, than when focus was at 5 cm below the transducer, the same position as tumors (p < 0.01). Tumors were measured 11.8% +/- 2.9% bigger when they were 8-cm deep below the transducer than when they were 5-cm deep below the transducer (p < 0.001). Setting focus at the same position as tumors and keeping tumor depth consistent during serial 3-D US examinations may be necessary for reliable volumetric assessment of tumors.

Agar↗

PubMed2004

Acute iliofemoral deep vein thrombosis: evaluation of underlying anatomic abnormalities by spiral CT venography.

PURPOSE: To evaluate the spectrum of underlying anatomic abnormalities in iliofemoral deep vein thrombosis (DVT) by spiral computed tomographic (CT) venography. MATERIALS AND METHODS: During the past 4 years, 56 patients with acute iliofemoral DVT have been evaluated by CT venography at our institution. Forty-four patients had left-sided DVT, nine had right-sided DVT, and the remaining three had DVT in both extremities. CT venography was performed with use of 2.5-3.2-mm x-ray beam collimation and a 1.25-2.0-mm reconstruction interval. Spiral scans were initiated 5 minutes after intravenous contrast medium injection. The CT venograms were correlated with catheter venograms. In addition, with use of axial sections and their three-dimensional reconstructions, including multiplanar reformation and volume rendering, the presence or absence of central obstructing lesions and their causes were evaluated. RESULTS: Among 44 patients with left-sided DVT, 37 had significant anatomic abnormalities in their iliofemoral veins or inferior vena cava (IVC). The most common lesion was left common iliac vein compression by the right common iliac artery (n = 27; exaggerated by a bony spur in nine and associated with extrinsic compression by the left internal iliac artery in two). Of the nine patients with right-sided DVT, six had significant anatomic abnormalities including encasement or extrinsic compression of their iliac veins by various causes (n = 3) and venous stricture without extrinsic lesions (n = 3). Among three patients with DVT in both extremities, two had anatomic abnormalities in the IVC. Therefore, 45 of 56 patients had anatomic abnormalities central to the thrombosed deep veins. CONCLUSION: The majority of patients with acute iliofemoral DVT had underlying anatomic abnormalities. The presence of central stenosis or obstruction and their causes can be evaluated by spiral CT venography.

Adolescent↗

PubMed2004

Efficacy and safety of a retrieval hook for removal of retrievable expandable tracheobronchial stents.

PURPOSE: To evaluate the efficacy and safety of use of a retrieval hook for removal of retrievable expandable tracheobronchial stents. MATERIALS AND METHODS: With fluoroscopic guidance, a retrieval hook was used to remove 45 retrievable expandable tracheobronchial stents in 31 patients. Indications for stent removal included tissue hyperplasia (n = 16), stent migration (n = 10), stent misplacement (n = 2), tumor overgrowth (n = 2), persistent gastrobronchial fistula (n = 1), and incompletely expanded stent (n = 1). Thirteen stents were electively removed after temporary use. The success rate, causes of failure, and complications related to stent removal with a retrieval hook were analyzed. RESULTS: Forty-one of 45 stents (91.1%) were successfully removed with a retrieval hook. The following difficulties were encountered: disruption of the polyurethane membrane (n = 3) and an untied drawstring (n = 1). The removal procedure failed in four cases (8.9%) because of excessive tissue hyperplasia (n = 4) in the proximal portion of the stent. The hook wire fractured in two of the four failed cases. The overall complication rate was 4.4% (minor bleeding, n = 2). CONCLUSION: For complications with or temporary use of retrievable expandable tracheobronchial stents, removal with a retrievable hook shows promising initial results.

Adult↗

PubMed2004

Transcatheter arterial embolization with 188Rhenium-HDD-labeled iodized oil in rabbit VX2 liver tumor.

PURPOSE: To evaluate the antitumor effect of transcatheter arterial embolization (TAE) with use of rhenium 188 HDD (4-hexadecyl 2,2,9,9-tetramethyl-4,7-diaza-1,10-decanethiol)-labeled iodized oil and to compare it with that of transcatheter arterial chemoembolization (TACE) with use of an established chemotherapeutic agent and iodized oil in experimentally induced liver tumor. MATERIALS AND METHODS: VX2 carcinoma was grown in the livers of 57 rabbits. TAE was performed with (188)Re-HDD-labeled iodized oil (Re-Lp group; n = 21), doxorubicin/iodized oil emulsion (Dx-Lp group; n = 21), and iodized oil alone (n = 15). Sequential conjugated planar imaging was performed for dosimetry of the radioisotope in the Re-Lp group (n = 15). Growth ratio and percentage of viable tumor were estimated by computed tomography and histopathologic examination. Hepatic and hematologic toxicities were evaluated by biochemical analysis. RESULTS: On conjugated planar imaging, radioactivity was concentrated on the tumor (effective half-life, 16.2 hours), and mean radiation dose to the tumor was 147.7 Gy. The mean growth ratios 1, 2, and 3 weeks after TAE and the percentage of viable tumor in the Re-Lp group (-3.4, -7.6, -11.1, and 0.3%) and the Dx-Lp group (-3.2, -5.3, 29.0, and 2.6%) were significantly lower than the respective values in the iodized oil group (45.5, 145.4, 283.0, and 30.1%; P < .001). However, the differences between the values in the Re-Lp group and those in the Dx-Lp group were not significant (P values of .165-0.497 for growth ratios; P = .134 for percentage of viable tumor). There was similar transient hepatotoxicity in all three groups. CONCLUSIONS: TAE with (188)Re-HDD-labeled iodized oil has potent antitumor effect in VX2 liver tumor that is comparable with that of TACE with an established chemotherapeutic agent.

Animals↗

PubMed2004

A dual expandable nitinol stent: experience in 102 patients with malignant gastroduodenal strictures.

PURPOSE: To investigate the technical feasibility and clinical effectiveness of a dual expandable nitinol stent in the palliative treatment of malignant gastroduodenal strictures. MATERIALS AND METHODS: The dual stent consisted of two stents, an outer partially covered stent and an inner bare nitinol stent. The outer diameter of the stent delivery system was 3.8 mm. With fluoroscopic guidance, the outer stent was placed into the stricture, followed by coaxial placement of the inner stent. The stent placement was attempted in 102 consecutive patients with malignant gastroduodenal strictures. The underlying causes of malignant strictures were gastric cancer (n = 55), pancreatic cancer (n = 24), gallbladder cancer (n = 7), cholangiocarcinoma (n = 5), duodenal cancer (n = 5), and metastatic cancer (n = 6). All patients presented with symptoms of gastric outlet obstruction. RESULTS: Stent placement was technically successful and well tolerated in 101 of 102 patients (99%). After stent placement, 85 of the 101 patients (84%) with technical success experienced improvement of their symptoms. Tumor overgrowth occurred in five patients, stent migration in two, mucosal hyperplasia in one, bleeding in one, and jaundice in two. Seventy one of the 101 patients died 5 to 340 days (mean, 71 days) after stent placement from progression of their disease, myocardial infarction, bleeding, or sepsis. The remaining 30 patients are still alive 6 to 227 days (mean, 39 days) after stent placement. The 30-day, 60-day, 90-day, and 180-day survival rates were 78%, 58%, 39%, and 8%, respectively. CONCLUSION: The dual stent with a 3.8-mm stent delivery system is easy to insert, safe, and reasonably effective for the palliative treatment of malignant gastroduodenal strictures.

Adult↗

PubMed2004

Removal of retrievable esophageal and gastrointestinal stents: experience in 113 patients.

OBJECTIVE: Although there are frequent clinical situations in which esophageal and gastrointestinal stents should be removed, nonsurgical stent removal has been difficult. The purpose of our study was to describe the safety and efficacy of removing the retrievable nitinol stents with a retrieval hook. MATERIALS AND METHODS: Under fluoroscopic guidance, the removal of 119 esophageal, six gastroduodenal, and five rectal retrievable stents was attempted in 113 patients using a retrieval hook. Indications for stent removal included migration (n = 35), severe pain (n = 23), formation of a new stricture (n = 13), incomplete stent expansion (n = 7), airway compression (n = 2), esophagorespiratory fistula (n = 2), malpositioned stent (n = 1), and hematemesis (n = 1). The remaining 46 stents were electively removed. RESULTS: Of the 130 stents, 127 (97.7%) were successfully removed despite the following difficulties: untied drawstrings (n = 4), separation of the stent (n = 3), and fracture (n = 2) or disconnection (n = 2) of a retrieval hook. The removal procedure failed in three cases (2.3%). The causes of failure were the inability to place the hook into the migrated stent (n = 2) and a tight stricture above the migrated stent (n = 1). The procedure-related complications included minor (n = 4) and major (n = 1) bleeding and intramural rupture (n = 3). One patient died of major bleeding after removal of an esophageal stent. CONCLUSION: The stent retrieval hook is useful for removing retrievable esophageal and gastrointestinal stents.

Adolescent↗

PubMed2003

Transcatheter arterial chemoembolization with paclitaxel-lipiodol solution in rabbit VX2 liver tumor.

PURPOSE: To evaluate the antitumor effects of transcatheter arterial chemoembolization (TACE) with a solution of an anticancer drug (Paclitaxel; Bristol-Myers Squibb, Princeton, NJ) and iodized oil (Lipiodol; Laboratoire Gurerbet, Aulnay-Sous-Bois, France) (hereafter, the solution), as well as intratumor concentration and hepatotoxicity, in experimentally induced liver tumor. MATERIALS AND METHODS: VX2 carcinoma was grown in livers of 30 rabbits. In 18 rabbits, TACE was performed with the high-dose solution (4 mg anticancer drug and 0.4 mL iodized oil, n = 6), the low-dose solution (1 mg anticancer drug and 0.4 mL iodized oil, n = 6), or iodized oil alone (0.4 mL, n = 6) in a control group. One week later, the growth ratio and residual viable proportion of the tumors were calculated on the basis of findings at spiral computed tomography and histopathologic examination. Hepatic and hematologic toxicities were evaluated by means of biochemical analysis. Differences between the three groups were statistically assessed with the Kruskal-Wallace and Mann-Whitney U tests. The remaining 12 animals were treated with the high-dose solution and serially sacrificed for clarification of chronologic change of concentration of the anticancer drug in liver tissues. RESULTS: Growth ratios and residual viable proportions of the tumors were significantly lower in the solution groups (high dose, 3.3% +/- 6.2 [mean +/- SD] and 2.8% +/- 3.6, respectively; low dose, 18.7% +/- 7.4 and 12.7% +/- 6.1, respectively) than in the control group (68.3% +/- 12.7 and 31.1% +/- 8.8, respectively) (P <.05). Hepatotoxicity was transient in all but one rabbit, which died 2 days after TACE with substantial biochemical changes. The anticancer drug accumulated in tumor where the concentration peaked at day 3 and returned to levels comparable to those for normal hepatic parenchyma at 7 days after TACE. CONCLUSION: TACE with the Paclitaxel-Lipiodol solution has dose-dependent antitumor effects without major toxicities in VX2 liver tumor.

Animals↗

PubMed2003

Clogging of drainage catheters: quantitative and longitudinal assessment by monitoring intracatheter pressure in catheters and rabbits.

PURPOSE: To develop a method for the quantitative and longitudinal assessment of clogging in drainage catheters and to confirm the validity of the method. MATERIALS AND METHODS: Intracatheter pressure was measured during the infusion of saline at a rate of 0.1-3.0 mL/sec in nine catheters with different internal diameters. With the data obtained, a fitting equation between the intracatheter pressure and internal diameter was derived on the basis of the Poiseuille law. To confirm the validity of this measurement method, four drainage catheters were inserted into the peritoneal cavity in each of 15 rabbits. Intracatheter pressures at infusion rates of 0.1 and 0.5 mL/sec were monitored for 14 days, while the degrees of catheter clogging were graded on the basis of the different frequencies of manual irrigation: one, two, or three times per day. Repeated measures analysis of variance was used to determine the statistical significance of differences in pressure between different irrigation frequencies. RESULTS: Pressure was measured successfully throughout the experiment except in three rabbits with dislodged catheters. Three to 14 days after catheter insertion, the pressures were significantly lower in catheters with higher irrigation frequencies than in those with lower irrigation frequencies (P <.05). The effective internal diameter of each catheter could be monitored by means of the derived fitting equation. CONCLUSION: This method can be used to quantitatively measure the degree of clogging of a drainage catheter. It can also be used for comparative or longitudinal in vivo studies concerning the effectiveness of drainage procedures or catheter development.

Abscess↗

PubMed2003

Vascular responses in normal canine carotid arteries: comparison between various self-expanding stents of the same unconstrained size.

RATIONALE AND OBJECTIVES: To compare long-term vascular responses upon the insertion of various self-expandable stents, all the same unconstrained size, in canine carotid artery models. MATERIALS AND METHODS: Twenty-two stents (5 SMARTs, 5 Wallstents, 6 Niti-Ss, 6 Niti-Ds) of the same unconstrained size (6 mm in diameter, 20 mm in length) were endovascularly placed in canine common carotid arteries. The luminal changes were measured on three occasions, on prestenting, immediate poststenting, and angiograms taken before specimens were killed. After en-bloc harvest of the stented carotid arteries at 6 months, the intraluminal surface was evaluated by gross observation and scanning electron microscopy (SEM). Neointimal thickness was measured at several points both over the wire and between the wires. RESULTS: Niti-D was excluded from analysis because of high rate of poststenting occlusion. SMART stent showed the greatest expansibility with average initial luminal gain ( < 0.05) of 21.2% (Niti-S: 16.5%, Wallstent: 12.9%). At 6 months follow-up, the dilated arterial lumen had returned almost to the prestenting caliber without any significant differences among the stent types ( > 0.05). The thickness of neointimal coverage was more prominent with SMART stent (354 microm over the wire and 258 microm between the wires) than Niti-S (228 microm and 83 microm) or Wallstent (187 microm and 78 microm). CONCLUSION: Stent types with its higher initial luminal gain appeared to be associated with thicker neointimal formation at 6 months. The acute expanding force of a self-expanding stent may be the key to the cause of neointimal hyperplasia. Regardless of the inserted stent type, the variations in neointimal response were offset by luminal gains of varying degree, thus preserving the arterial patency almost to the prestenting size.

Analysis of Variance↗

PubMed2003

Experimental clonorchiasis in dogs: CT findings before and after treatment.

PURPOSE: To determine whether disease activity in clonorchiasis can be assessed with dynamic computed tomography (CT). MATERIALS AND METHODS: Ten dogs infected with metacercariae of Clonorchis sinensis underwent serial dynamic CT examinations. Five dogs were sacrificed 14 weeks after infection, and another five infected dogs were treated with praziquantel at the 14th week and continued to undergo CT examinations until death or sacrifice at the 25th (n = 1) or 40th week (n = 4). CT images were evaluated for dilatation of the bile ducts, contrast enhancement of bile duct walls and adjacent hepatic parenchyma, visualization of flukes within the bile ducts, and presence of calcifications. Changes in CT findings were analyzed statistically by using a mixed linear model and a generalized estimating equations model. RESULTS: Dilatation of the bile ducts, contrast enhancement of the ductal walls, transient hepatic attenuation differences, and flukes per se were observed at CT from the 2nd through the 5th week, were most apparent between the 5th and 13th weeks, and disappeared or decreased markedly in degree after treatment in all dogs (P <.05). Nodular calcifications were observed at CT after treatment in two dogs. Histopathologic examination revealed proliferation and enlargement of arteries in the periductal area and the portal tracts and congestion of hepatic sinusoids during the acute phase. Treatment was associated with periductal hyalinization, degeneration of the periductal arteries, and calcification of the ductal epithelium. CONCLUSION: Disease activity in experimental canine clonorchiasis can be assessed with dynamic CT.

Animals↗