A mixed control chart for monitoring failure times under accelerated hybrid censoring.

In an accelerated hybrid censoring scheme several stress factors can be accelerated to make the products to respond to fail more quickly than under normal operating conditions. In such situations, the control charts available in the literature cover the attribute characteristics only to monitor the performance of the process over time. This study extends the idea by proposing an optimal mixed attribute-variable control chart for Weibull distribution under an accelerated hybrid censoring scheme keeping the advantages of both attribute and variable control charts. It first monitors the number of defectives under accelerated conditions and switches to the variable control chart to investigate the mean failure times when the process stability is dubious. The performance of the proposed chart is evaluated by using run-length characteristics, and the optimality of the design parameter is achieved by minimizing the out-of-control average run length. The simulation study depicted better performance of the proposed control chart than the traditional charts in detecting shifts in the process. A real-life application is also included.

Preoperative chemoradiation with irinotecan and capecitabine in patients with locally advanced resectable rectal cancer: long-term results of a Phase II study.

PURPOSE: Preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer has shown benefit over postoperative CRT; however, a standard CRT regimen has yet to be defined. We performed a prospective concurrent CRT Phase II study with irinotecan and capecitabine in patients with locally advanced rectal cancer to investigate the efficacy and safety of this regimen. METHODS AND MATERIALS: Patients with locally advanced, nonmetastatic, and mid-to-lower rectal cancer were enrolled. Radiotherapy was delivered in 1.8-Gy daily fractions for a total of 45 Gy in 25 fractions, followed by a coned-down boost of 5.4 Gy in 3 fractions. Concurrent chemotherapy consisted of 40 mg/m(2) of irinotecan per week for 5 consecutive weeks and 1,650 mg/m(2) of capecitabine per day for 5 days per week (weekdays only) from the first day of radiotherapy. Total mesorectal excision was performed within 6 ± 2 weeks. The pathologic responses and survival outcomes were included for the study endpoints. RESULTS: In total, 48 patients were enrolled; 33 (68.7%) were men and 15 (31.3%) were women, and the median age was 59 years (range, 32-72 years). The pathologic complete response rate was 25.0% (11 of 44; 95% confidence interval, 12.2-37.8) and 8 patients (18.2% [8 of 44]) showed near-total tumor regression. The 5-year disease-free and overall survival rates were 75.0% and 93.6%, respectively. Grade 3 toxicities included leukopenia (3 [6.3%]), neutropenia (1 [2.1%]), infection (1 [2.1%]), alanine aminotransferase elevation (1 [2.1%]), and diarrhea (1 [2.1%]). There was no Grade 4 toxicity or treatment-related death. CONCLUSIONS: Preoperative CRT with irinotecan and capecitabine with treatment-free weekends showed very mild toxicity profiles and promising results in terms of survival.

Implementation of Medical Information Exchange System Based on EHR Standard.

OBJECTIVES: To develop effective ways of sharing patients' medical information, we developed a new medical information exchange system (MIES) based on a registry server, which enabled us to exchange different types of data generated by various systems. METHODS: To assure that patient's medical information can be effectively exchanged under different system environments, we adopted the standardized data transfer methods and terminologies suggested by the Center for Interoperable Electronic Healthcare Record (CIEHR) of Korea in order to guarantee interoperability. Regarding information security, MIES followed the security guidelines suggested by the CIEHR of Korea. This study aimed to develop essential security systems for the implementation of online services, such as encryption of communication, server security, database security, protection against hacking, contents, and network security. RESULTS: The registry server managed information exchange as well as the registration information of the clinical document architecture (CDA) documents, and the CDA Transfer Server was used to locate and transmit the proper CDA document from the relevant repository. The CDA viewer showed the CDA documents via connection with the information systems of related hospitals. CONCLUSIONS: This research chooses transfer items and defines document standards that follow CDA standards, such that exchange of CDA documents between different systems became possible through ebXML. The proposed MIES was designed as an independent central registry server model in order to guarantee the essential security of patients' medical information.

Manual and automated polyp measurement comparison of CT colonography with optical colonoscopy.

RATIONALE AND OBJECTIVES: The purpose of this study was to assess (1) the agreement of two-dimensional (2D) and three-dimensional (3D) manual and automated polyp linear diameter measurements at CT colonography (CTC), with optical colonoscopic equivalents and (2) intraobserver and interobserver agreement of the CTC measurements. MATERIALS AND METHODS: Using the same CTC system, two radiologists independently measured the maximum linear diameter of 44 polyps (reference size 3-15 mm) matched on CTC and optical colonoscopy: manual 2D optimized multiplanar reformatted planes with standard window settings (level 1500 HU, width -200 HU), manual 3D measurement with software calipers and automated 3D measurement with software. After 2 weeks, polyps were measured again. Compatibility of CTC measurement with that of optical colonoscopy and measurement reproducibility was assessed statistically. RESULTS: In the manual measurement, 44 polyps were analyzed and 41 in automated measurement; three polyps could not be extracted. Although the measurement difference was noted for automated, manual 3D, and manual 2D measurements, statistically supported agreement with optical colonoscopic measurement was noted only with manual 2D measurement for both observers. However, 95% limits of agreement were wide for all the measurement methods. When categorized according to the optical colonoscopic measurement, manual 2D, 3D, and automated measurements showed "good" agreement. Although intraobserver and interobserver agreement was good with manual measurement, intraobserver and interobserver agreement was excellent with automated measurement. CONCLUSION: Manual 2D measurements demonstrated trends of better approximation to optical colonoscopy measurements than manual 3D or automated measurements. And automated measurement eliminated intraobserver and interobserver variability. For noninvasive CTC surveillance, manual 2D measurements are expected to measure medium-sized polyps with sufficient agreement with optical colonoscopic measurements and excellent intraobserver and interobserver variability, especially if combined with automated measurement.

Area of paradoxical signal drop after the administration of superparamagnetic iron oxide on the T2-weighted image of a patient with lymphangitic metastasis of the liver.

We report a geographic area of prominent hypointensity in T2-weighted images vs. normal adjacent liver parenchyma in a patient with cholangiocarcinoma and lymphangitic metastasis of the liver after superparamagnetic iron oxide (SPIO) administration. The area showing this prominent signal drop showed Kupffer cell proliferation and lymphangitic metastasis during a pathologic examination.

Identification of mitochondrial FoF1-ATP synthase involved in liver metastasis of colorectal cancer.

Liver metastasis is a major cause of poor survival of colorectal cancer patients. In order to identify the proteins associated with liver metastasis in colorectal cancer, we carried out two-dimensional gel electrophoresis-based comparative proteomic analysis of normal colon mucosa, primary colon cancer tissue and corresponding metastatic tumor tissue in liver. The proteins identified were further validated by immunohistochemical analysis of 67 quadruplet samples of normal colon primary colorectal cancer and normal liver-synchronous liver metastasis, and 251 colorectal cancers as well as in vitro invasion assay of the human colon cancer cell line, SNU-81. From proteomic assessment, the mitochondrial FoF1-ATP synthase (ATP synthase) alpha-subunit was identified as a protein that is upregulated in liver metastasis compared with the primary tumor. Immunohistochemical analyses confirmed a significant increase in the expression of ATP synthase alpha- and d-subunits in synchronous liver metastasis compared with primary tumor and normal mucosa, respectively. ATP synthase alpha- and d-subunits were overexpressed in 197 (78.5%) and 190 (75.7%), respectively, of the 251 colorectal cancers. The alpha- and d-subunits were significantly associated with liver metastasis (P < 0.05) as well as low histological grade (P < 0.0001). The d-subunit also correlated with venous invasion (P = 0.026) and distant metastasis (P = 0.032). In stage III cancers, d-subunit expression was independently associated with poor survival (P = 0.017). Furthermore, transfection of small interfering RNA targeted to ATP synthase alpha- and d-subunits resulted in decreased in vitro invasiveness of the human colon cancer cell line. Our overall findings demonstrate that increased ATP synthase is associated with liver metastasis of colorectal cancer.

Comparison of 5-fluorouracil/leucovorin and capecitabine in preoperative chemoradiotherapy for locally advanced rectal cancer.

PURPOSE: To describe our experience with a bolus injection of 5-fluorouracil and leucovorin (FL) vs. capecitabine in terms of radiologic and pathologic findings in preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer. METHODS: The study enrolled 278 patients scheduled for preoperative CRT using two protocols with different chemotherapeutic regimens. Pelvic radiotherapy (50.4 Gy) was delivered concurrently with FL (n = 145) or capecitabine (n = 133). Surgery was performed 6 weeks after CRT completion. Tumor responses to CRT were measured using both radiologic and pathologic examination. Magnetic resonance volumetry was performed at the initial workup and just before surgery after completion of preoperative CRT. Post-CRT pathology tests were used to determine tumor stage and regression. RESULTS: Radiologic examination showed that tumor volume decreased by 68.2% +/- 20.5% in the FL group and 68.3% +/- 22.3% in the capecitabine group (p = 0.970). Postoperative pathologic T stage determination showed that downstaging occurred in 44.3% of FL and 49.9% of capecitabine patients (p = 0.571). The tumor regression grades after CRT were Grade 1 (minimal response) in 22.6% and 21.0%, Grade 2 (moderate response) in 53.2% and 50.0%, Grade 3 (near-complete response) in 12.9% and 12.9%, and Grade 4 (complete response) in 11.3% and 16.1% of the FL and capecitabine groups, respectively (p = 0.758). CONCLUSION: In the present study, the radiologic and pathologic findings did not reveal significant differences in short-term tumor responses between preoperative FL and capecitabine CRT for locally advanced rectal cancer. Long-term results and a prospective randomized trial are needed.

CT Differentiation of cholangiocarcinoma from periductal fibrosis in patients with hepatolithiasis.

OBJECTIVE: The objective of our study was to determine useful CT findings for differentiating cholangiocarcinoma from periductal fibrosis in patients with hepatolithiasis. MATERIALS AND METHODS: CT images of 30 patients with hepatolithiasis and pathologically proven cholangiocarcinoma (n = 14) or periductal fibrosis (n = 16) were retrospectively reviewed. Helical CT scans were obtained before, 30 seconds after, and 65 seconds after the start of contrast material injection. Analysis of CT findings included evaluation for the presence of periductal soft-tissue density, bile duct wall thickening at the stricture site, ascites, portal vein obliteration, lymph node enlargement, and a duct stone; assessment of the degree of ductal dilatation; and evaluation of the enhancement pattern of periductal lesions, thickened ductal wall, and hepatic parenchyma. The CT attenuation coefficients of the thickened ductal wall and adjacent normal-looking bile duct were measured on images obtained during each phase. Among these findings, statistically significant variables were determined using the Fisher's exact test and Student's t test. Sensitivity and specificity values of the CT criteria were also calculated. RESULTS: The presence of periductal soft-tissue density (p = 0.002), higher enhancement of the duct than adjacent bile duct on portal venous phase images (p = 0.008), ductal wall thickening (p = 0.026), portal vein obliteration (p = 0.031), and lymph node enlargement (p = 0.031) were found to be the significant findings for differentiating cholangiocarcinoma from fibrosis in patients with hepatolithiasis. When any two or more of these five criteria were used in combination, we could identify 100% of the patients with cholangiocarcinoma but only 12.5% of the patients with fibrosis. CONCLUSION: Cholangiocarcinoma in patients with hepatolithiasis can be diagnosed using specific CT criteria.

Comparison of the accuracy of magnetic resonance imaging and positron emission tomography/computed tomography in the presurgical detection of lymph node metastases in patients with uterine cervical carcinoma: a prospective study.

BACKGROUND: The objective of the current study was to determine the accuracy of magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) for detecting lymph node metastases in patients with uterine cervical carcinoma compared with thin-section histopathologic results from systemic lymphadenectomy. METHODS: Twenty-two patients with International Federation of Obstetrics and Gynecology (FIGO) Stage IB-IVA cervical carcinoma who underwent both MRI and PET/CT before lymphadenectomy were included in this study. Lymphadenectomy involved removing all visible lymph nodes in the surgical fields. To enable region-specific comparisons, paraaortic and pelvic lymph nodes were divided into seven regions: the paraaortic area, both common iliac areas, both external iliac areas, and both internal iliac/obturator areas. Histopathologic evaluation of lymph nodes was the diagnostic standard. Chi-square analysis was used to compare the accuracy of MRI and PET/CT for the detection of metastatic lymph nodes. A P value < or = 0.05 was considered statistically significant. RESULTS: With MRI, the sensitivity, specificity, and accuracy rates for detecting metastatic lymph nodes in each lymph node group were 30.3% (10 of 33 lymph node groups), 92.6% (112 of 121 lymph node groups), and 72.7% (122 of 154 lymph node groups), respectively; with PET/CT, those rates were 57.6% (19 of 33 lymph node groups), 92.6% (112 of 121 lymph node groups), and 85.1% (131 of 154 lymph node groups), respectively. Statistical analysis showed that PET/CT was more sensitive than MRI (P = 0.026) but that there were no statistical differences noted with regard to specificity (P = 1.000) or accuracy (P = 0.180). Power analysis demonstrated that a sample size of 685 lymph node groups (98 patients) would be necessary to demonstrate that PET/CT was more accurate than MRI (alpha = 0.05; beta = 0.80). CONCLUSIONS: PET/CT was more sensitive than MRI for detecting lymph node metastases in patients with uterine cervical carcinoma.

Hepatic attenuation differences associated with obstruction of the portal or hepatic veins in patients with hepatic abscess.

OBJECTIVE: The purpose of our study was to determine the nature of the association between the attenuation difference of the hepatic parenchyma surrounding an abscess and obstruction of the regional portal vein or of the hepatic vein. MATERIALS AND METHODS: Helical CT scans of 60 patients with hepatic abscess were analyzed for the presence of complete or partial obstruction of the portal or hepatic veins and for attenuation differences in the surrounding parenchyma. Clinical (age, sex, underlying disease, and microorganism) and CT (obstruction of the portal or hepatic vein and number, location, and size of abscesses) findings were analyzed statistically for possible associations with each of regional parenchymal hyper- and hypoattenuation by using the chi-square test and multivariate logistic regression analysis. RESULTS: Regional parenchymal hyperattenuation was identified in 40 patients (67%). More patients with portal vein obstruction showed regional parenchymal hyperattenuation than patients without portal vein obstruction (22/27 patients vs 18/33, p = 0.028), and more patients with hepatic vein obstruction showed regional parenchymal hypoattenuation than those without hepatic vein obstruction (11/21 vs 3/39, p = 0.0003). Multivariate logistic regression analysis showed that portal venous obstruction was the only statistically significant predictor of regional parenchymal hyperattenuation (p = 0.032; odds ratio, 3.7) and that parenchymal hypoattenuation was associated with hepatic venous obstruction (p = 0.001; odds ratio, 44.9). CONCLUSION: Parenchymal hypo- and hyperattenuation are frequently observed in the hepatic region surrounding an abscess on dynamic CT. Moreover, these parenchymal attenuation differences are associated with regional portal or hepatic vein obstruction.

Small-bowel obstruction in a phantom model of ex vivo porcine intestine: comparison of PACS stack and tile modes for CT interpretation.

PURPOSE: To compare computed tomographic (CT) image interpretation with picture archiving and communication systems (PACS) stack and tile modes for speed and accuracy of transition zone localization in small-bowel obstruction by using ex vivo porcine specimens. MATERIALS AND METHODS: Twenty-five small-bowel obstruction phantom models made of ex vivo porcine intestines from a slaughterhouse were imaged at CT. One was used for observer training, and 24 were used for experimentation. At 20-cm intervals throughout the intestines, metallic markers were placed in the mesenteries immediately adjacent to bowel. One obstruction was made in each intestine, midway between markers, by ligating intestine with a 3-0 silk suture to simulate mechanical small-bowel obstruction. The lumen proximal to the ligation site was distended with air and a soybean oil-iodized oil mixture until at least two-thirds of the proximal intestine exceeded 2.0 cm in transverse diameter. Dilated segments were 310-550 cm in length. Soybean oil and a mixture of soybean and iodized oil were used to simulate differences in attenuation among bowel wall, intraluminal fluid, and extraluminal abdominal fat. Four experienced abdominal radiologists independently determined the transition zone by using stack mode (cine viewing of stacked images) and, at least 2 weeks later, tile mode (side-by-side image display). Accuracy and degree of error in counting markers were evaluated, and speed of interpretation was recorded. Statistical analysis was performed with the McNemar and Wilcoxon signed rank tests. RESULTS: For all observers, accuracy of transition zone localization tended to be better with stack mode (63%-83% [15-20 phantoms]) than with tile mode (50%-63% [12-15 phantoms]), but the differences were not significant. For each observer, mean counting error was lower in stack mode (range, 0.96-2.48) than in tile mode (range, 1.74-3.22), with significance for three observers (P < .01, P < .01, and P = .04). Interpretation was significantly faster with stack mode by a factor of two to three for all observers (P < .01). CONCLUSION: Stack mode evaluation for identification of the transition zone in obstructed small bowel is faster than evaluation with tile mode. Accuracy is not significantly different between modes, although there is a tendency toward better results with stack mode.

In vitro CT evaluation of intrahepatic stones: correlation with chemical composition.

OBJECTIVE: To describe in vitro CT features of intrahepatic stones and to correlate CT attenuation with chemical composition. MATERIALS AND METHODS: Of the patients who underwent choledochoscopic intrahepatic stone removal between 1998 and 2001, 54 patients with stones larger than 3 mm were enrolled in this study. In each case, a chemical compositional analysis was performed to determine calcium, cholesterol, total bilirubin, and inorganic phosphorus compositions. The three largest stones obtained from each patient were imaged by CT. CT attenuation numbers were measured in the center images of each stone by drawing free-hand region of interest (ROI). The measured CT attenuation numbers were correlated with their chemical composition. Also, CT attenuation numbers of stones were compared with that of the liver on non-contrast CT (50-70 HU). RESULTS: Stone size ranged from 3.1 to 10.5 mm (mean +/- S.D.: 6.0 +/- 1.4). The CT attenuation numbers (HU) of stones ranged from 36.4 to 410.19 (mean +/- S.D.: 94.6 +/- 49.9). CT numbers of stones were below 70 HU in 11 patients (20.4%), and below 90 HU in 33 patients (59.3%). The chemical analysis data of the stones were as follows: calcium (0.5-6.5 wt.%; mean +/- S.D., 2.6 +/- 1.4), total bilirubin (0.45-24.4 wt.%; 13.1 +/- 6.2), cholesterol (5.4-73.9 wt.%; 29.3 +/- 17.4), phosphorus (0.1-1.2 wt.%; 0.6 +/- 0.3), and non-soluble residue (17.6-85.4 wt.%; 57.0 +/- 22.6). There was a weak but significant correlation between calcium composition and CT attenuation (r = 0.38, P < 0.01) and no significant correlation between other chemical compositions and the CT attenuation (cholesterol, r = 0.01, P > 0.01; total bilirubin, r = 0.05, P > 0.01; phosphorus, r = 0.01, P > 0.01). CONCLUSION: On non-contrast CT, intrahepatic stones would not be hyperattenuating with respect to liver parenchyma in about one fifth of patients. The CT attenuation of stones correlates with calcium and does not correlate with any other chemical composition.

Palliation of anastomotic obstructions in recurrent gastric carcinoma with the use of covered metallic stents: clinical results in 25 patients.

BACKGROUND: The purpose of this study was to investigate the technical feasibility and the clinical effectiveness of the placement of covered self-expandable metallic stents for the treatment of anastomotic obstructions in recurrent gastric carcinoma. METHODS: With fluoroscopic guidance, covered stents were placed in 25 patients with recurrent gastric carcinoma for the palliation of obstructions at anastomotic sites (14 gastrojejunostomy, 11 esophagojejunostomy). All patients had severe nausea and recurrent vomiting before the stent placement. RESULTS: Stent placement was technically successful in 24 patients (96%). After stent placement, symptoms improved in all 24 patients. During the follow-up of 2 to 65 weeks (mean, 13.7 weeks), stent migration occurred in 1 patient 16 days after the procedure. He needed percutaneous catheter drainage because of an abscess, which was followed by esophagojejunostomy site rupture during a second stent trial. Stricture recurred in 4 patients because of tumor overgrowth 10 to 55 weeks after the procedure; all patients underwent coaxial placement of a second stent and had good oral intake. CONCLUSIONS: The placement of covered expandable metallic stents seems to be both technically feasible and an effective means for the palliation of anastomotic obstructions in recurrent gastric carcinoma. This procedure can be considered to be the primary choice for the palliation in those patients.

Ruptured corpus luteal cyst: CT findings.

OBJECTIVE: To evaluate the CT findings of ruptured corpus luteal cysts. MATERIALS AND METHODS: Six patients with a surgically proven ruptured corpus luteal cyst were included in this series. The prospective CT findings were retrospectively analyzed in terms of the size and shape of the cyst, the thickness and enhancement pattern of its wall, the attenuation of its contents, and peritoneal fluid. RESULTS: The mean diameter of the cysts was 2.8 (range, 1.5-4.8) cm; three were round and three were oval. The mean thickness of the cyst wall was 4.7 (range, 1-10) mm; in all six cases it showed strong enhancement, and in three was discontinuous. In five of six cases, the cystic contents showed high attenuation. Peritoneal fluid was present in all cases, and its attenuation was higher, especially around the uterus and adnexa, than that of urine present in the bladder. CONCLUSION: In a woman in whom CT reveals the presence of an ovarian cyst with an enhancing rim and highly attenuated contents, as well as highly attenuated peritoneal fluid, a ruptured corpus luteal cyst should be suspected. Other possible evidence of this is focal interruption of the cyst wall and the presence of peritoneal fluid around the adnexa.

Atypical low-signal-intensity renal parenchyma: causes and patterns.

Certain renal diseases manifest as low signal intensity of the renal parenchyma on magnetic resonance images. Sometimes, the appearance is sufficiently characteristic to allow a specific radiologic diagnosis to be made. The causes of this finding can be classified into three main categories on the basis of the pathophysiology: hemolysis, infection, and vascular disease. The first category includes paroxysmal nocturnal hemoglobinuria (PNH), hemosiderin deposition in the renal cortex from mechanical hemolysis, and sickle cell disease. The second category includes hemorrhagic fever with renal syndrome (HFRS). The third category includes acute renal vein thrombosis, renal cortical necrosis, renal arterial infarction, rejection of a transplanted kidney, and acute nonmyoglobinuric renal failure with severe loin pain and patchy renal vasoconstriction. These disease processes have different patterns of low signal intensity. PNH, hemosiderin deposition from mechanical hemolysis, and sickle cell disease involve the entire cortex including the columns of Bertin. HFRS involves the medulla, especially the outer medulla, whereas cortical necrosis involves the inner cortex including the columns of Bertin. In renal vein thrombosis, low-signal-intensity lesions involve the outer medulla, an appearance resembling that of HFRS. Wedge-shaped low-signal-intensity regions involving both the cortex and the medulla are seen in arterial infarction.

Three-dimensional ultrasonography using the minimum transparent mode in obstructive biliary diseases: early experience.

OBJECTIVE: To assess the feasibility of three-dimensional ultrasonography using the minimum transparent mode in patients with obstructive biliary disease. METHODS: Fourteen patients with obstructive jaundice underwent three-dimensional ultrasonography after conventional two-dimensional ultrasonography before interventional procedures. Three-dimensional images reconstructed by the minimum transparent mode were evaluated and compared with direct cholangiography. The minimum transparent mode images were compared with the two-dimensional ultrasonographic images to determine whether additional information was obtained. RESULTS: The level of obstruction was correctly depicted in all patients, and a dilated common bile duct, common hepatic duct, gallbladder, and main intrahepatic ducts were well visualized on minimum transparent mode images. The findings on minimum transparent mode images were well correlated with those on cholangiography; however, the perspective of the whole biliary tree on minimum transparent mode images was inferior to that on cholangiography in all cases. The overall image quality of minimum transparent mode images was poor in 6 patients, fair in 3, good in 4, and excellent in 1. The biliary anatomy was more objectively visualized on the minimum transparent mode images than conventional two-dimensional ultrasonographic images. CONCLUSIONS: Three-dimensional ultrasonography using the minimum transparent mode appears to be clinically feasible. The biliary anatomy was more objectively visualized on the minimum transparent mode images than conventional two-dimensional ultrasonographic images. Further technical development is needed to improve imaging resolution.

Fluoroscopically guided placement of a covered self-expandable metallic stent for malignant antroduodenal obstructions: preliminary results in 18 patients.

OBJECTIVE: The purpose of this study was to investigate the technical feasibility and the clinical effectiveness of fluoroscopically guided placement of covered self-expandable metallic stents in the treatment of malignant antroduodenal obstructions. SUBJECTS AND METHODS: With fluoroscopic guidance, covered self-expandable metallic stents were placed in 18 consecutive patients with inoperable malignant antroduodenal obstructions. All patients were treated for severe nausea and recurrent vomiting. RESULTS: Stent placement was technically successful in all patients with or without gastrostomy (n = 2) and balloon dilatation (n = 3). After stent placement, symptoms improved in all but one patient, who had another stenosis in the proximal jejunum. During the follow-up of 2-73 weeks (mean, 12 weeks), stent migration occurred in three patients (16.7%) from 1 to 41 days after the procedure. These patients were treated successfully by means of placing a second covered metallic stent. Two patients, who were followed up for longer than 30 weeks, showed a recurrence of strictures because of mechanical failure of the stents; one of the patients was treated with coaxial placement of a second covered metallic stent, which had a positive clinical outcome. CONCLUSION: Fluoroscopically guided placement of covered self-expandable metallic stents is technically feasible and effective for the palliative treatment of inoperable malignant antroduodenal obstructions. The rate of stent migration in our study was lower than those in previous reports.

MR findings of renal cortical necrosis.

PURPOSE: Evaluating the MR findings of renal cortical necrosis was the purpose of this study. METHOD: Eight series of T1-/T2-weighted (n = 8) and contrast-enhanced T1-weighted (n = 4) MR images in six patients with renal cortical necrosis diagnosed by renal biopsy (n = 4) or on clinical grounds (n = 2) were reviewed. In those who had follow-up MRI (n = 2) or comparable CT (n = 3), interval changes of MR findings and comparison with CT images were done. RESULTS: Swollen kidney with dark signal intensity rim involving the inner cortex and column of Bertin was noted on T2-and T1-weighted images. It was more conspicuous on T2-weighted images. The lesion did not enhance and was differentiated from uninvolved renal parenchyma. In the follow-up MRI, thickened dark signal intensity was more prominent and proved to be calcification or fibrosis. CONCLUSION: MRI, especially T2-weighted and contrast-enhanced T1-weighted imaging, was helpful in evaluating renal cortical necrosis.