Publications by authors named "Eugene K Choi"

33 Publications

Doppler US for suspicion of hepatic arterial ischemia in orthotopically transplanted livers: role of central versus intrahepatic waveform analysis.

Radiology 2013 Apr 7;267(1):276-84. Epub 2013 Jan 7.

Department of Radiology, Ronald Reagan UCLA Medical Center, David Geffen School of Medicine at UCLA, 757 Westwood Blvd, Los Angeles, CA 90097-1721, USA.

Purpose: To compare the diagnostic performance of combinations of parameters derived from main hepatic artery (MHA) and intrahepatic artery (IHA) waveforms at Doppler ultrasonography (US), with the aim of developing a systematic approach to the evaluation of the hepatic arteries in orthotopic liver transplants in patients suspected of having hepatic arterial ischemia.

Materials And Methods: This HIPAA-compliant retrospective study was approved by an institutional review board, with waiver of informed consent. From January 1, 2002, to November 1, 2011, 195 transplanted livers in 189 adults (129 men, 60 women; mean age, 53 years; age range, 18-73 years) who underwent Doppler US and follow-up (computed tomographic, magnetic resonance, or conventional) angiographic study within a 2-week interval were included. Diagnostic performance of the standard IHA and MHA criteria (resistive index [RI] < 0.5 and classic parvus tardus waveforms) with and without peak systolic velocity (PSV) thresholds (determined with receiver operating characteristic curve analysis) was assessed. The results of no-flow analysis and the most optimal MHA and IHA criteria were combined to create an algorithm, which was then applied to all liver transplants.

Results: The standard criteria (RI < 0.5 and classic parvus tardus) demonstrated greater sensitivity (80% vs 55%, P = .008) when applied to IHA waveforms compared with MHA waveforms. Optimal PSV cutoff values were less than 67 cm/sec and 39 cm/sec for MHA and IHA, respectively. The addition of a PSV threshold resulted in significant decrease in overall accuracy when applied to IHA (87% vs 73%, P < .001) and MHA (82% vs 66%, P = .002) criteria. Application of an algorithm reflecting a combination of the most optimal MHA and IHA criteria and the results of no-flow analysis resulted in 96% sensitivity and 83% specificity.

Conclusion: An algorithmic approach involving a tailored evaluation of the geographic distribution of absent flow and the quantitative parameters and waveform morphology of the MHA and IHAs allows for improved diagnostic performance in the detection of hepatic arterial complications in at-risk patients with orthotopic liver transplants.

Supplemental Material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120557/-/DC1.
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http://dx.doi.org/10.1148/radiol.12120557DOI Listing
April 2013

Transcatheter arterial chemoembolization for hepatic recurrence after curative resection of pancreatic adenocarcinoma.

Gut Liver 2010 Sep 24;4(3):384-8. Epub 2010 Sep 24.

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Background/aims: Despite curative resection, hepatic recurrences cause a significant reduction in survival in patients with primary pancreatic adenocarcinoma. Transcatheter arterial chemoembolization (TACE) has recently been used successfully to treat primary and secondary hepatic malignancy.

Methods: Between 2003 and 2008, 15 patients underwent TACE because of hepatic recurrence after curative resection of a pancreatic adenocarcinoma. The tumor response was evaluated based on computed tomography scans after TACE. The overall duration of patient survival was measured.

Results: After TACE, a radiographically evident response occurred in six patients whose tumors demonstrated a tumor blush on angiography. Four patients demonstrated stabilization of a hypovascular mass. The remaining five patients demonstrated continued progression of hypovascular hepatic lesions. The median survival periods from the time of diagnosis and from the time of initial TACE were 9.6 and 7.5 months, respectively.

Conclusions: TACE may represent a viable therapeutic modality in patients with hepatic recurrence after curative resection of pancreatic adenocarcinoma.
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http://dx.doi.org/10.5009/gnl.2010.4.3.384DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2956353PMC
September 2010

Hepatofugal portal flow on Doppler sonography in various pathological conditions: a pictorial essay.

J Clin Ultrasound 2009 Nov-Dec;37(9):511-24

Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Songpa-ku, Seoul 138-736, South Korea.

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http://dx.doi.org/10.1002/jcu.20624DOI Listing
January 2010

Node-by-node correlation between MR and PET/CT in patients with uterine cervical cancer: diffusion-weighted imaging versus size-based criteria on T2WI.

Eur Radiol 2009 Aug 11;19(8):2024-32. Epub 2009 Mar 11.

Department of Radiology, Asan Medical Center, University of Ulsan, 388-1 Poongnap dong, Songpa-gu, Seoul, 138-736, Korea.

The purpose of the study was to perform a node-by-node comparison of an ADC-based diagnosis and various size-based criteria on T2-weighted imaging (T2WI) with regard to their correlation with PET/CT findings in patients with uterine cervical cancer. In 163 patients with 339 pelvic lymph nodes (LNs) with short-axis diameter >5 mm, the minimum apparent diffusion coefficient (ADC), mean ADC, short- and long-axis diameters, and ratio of long- to short-axis diameters (L/S ratio) were compared in PET/CT-positive and -negative LNs. On PET/CT, 118 (35%) LNs in 58 patients were positive. The mean value of minimum and mean ADCs, short- and long-axis diameters, and L/S ratio were different in PET/CT-positive (0.6436 x 10(-3) mm(2)/s, 0.756 x 10(-3) mm(2)/s, 10.3 mm, 13.2 mm, 1.32, respectively) and PET/CT-negative LNs (0.8893 x 10(-3) mm(2)/s, 1.019 x 10(-3) mm(2)/s, 7.4 mm, 11.0 mm, 1.49, respectively) (P < 0.05). The Az value of the minimum ADC (0.864) was greater than those of mean ADC (0.836), short-axis diameter (0.764), long-axis diameter (0.640) and L/S ratio (0.652) (P < 0.05). The sensitivity and accuracy of the minimum ADC (86%, 82%) were greater than those of the short-axis diameter (55%, 74%), long-axis diameter (73%, 58%) and L/S ratio (52%, 66%) (P < 0.05). ADC showed superior correlation with PET/CT compared with conventional size-based criteria on T2WI.
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http://dx.doi.org/10.1007/s00330-009-1350-5DOI Listing
August 2009

Efficacy of barium-based fecal tagging for CT colonography: a comparison between the use of high and low density barium suspensions in a Korean population - a preliminary study.

Korean J Radiol 2009 Jan-Feb;10(1):25-33

Department of Radiology and Research Institute of Radiology and Internal Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Objective: This preliminarily study was designed to determine and to compare the efficacy of two commercially available barium-based fecal tagging agents for CT colonography (CTC) (high-density [40% w/v] and low-density [4.6% w/v] barium suspensions) in a population in Korea.

Materials And Methods: In a population with an identified with an average-risk for colorectal cancer, 15 adults were administered three doses of 20 ml 40% w/v barium for fecal tagging (group I) and 15 adults were administered three doses of 200 ml 4.6% w/v barium (group II) for fecal tagging. Excluding five patients in group I and one patient in group II that left the study, ten patients in group I and 14 patients in group II were finally included in the analysis. Two experienced readers evaluated the CTC images in consensus regarding the degree of tagging of stool pieces 6 mm or larger. Stool pieces were confirmed with the use of standardized CTC criteria or the absence of matched lesions as seen on colonoscopy. The rates of complete fecal tagging were analyzed on a per-lesion and a per-segment basis and were compared between the patients in the two groups.

Results: Per-lesion rates of complete fecal tagging were 52% (22 of 42; 95% CI, 37.7-66.6%) in group I and 78% (28 of 36; 95% CI, 61.7-88.5%) in group II. The difference between the two groups did not reach statistical significance (p = 0.285). The per-segment rates of complete tagging were 33% (6 of 18; 95% CI, 16.1%-56.4%) in group I and 60% (9 of 15; 95% CI, 35.7%-80.3%) in group II; again, the difference between the two groups did not reach statistical significance (p = 0.171).

Conclusion: Barium-based fecal tagging using both the 40% w/v and the 4.6% w/v barium suspensions showed moderate tagging efficacy. The preliminary comparison did not demonstrate a statistically significant difference in the tagging efficacy between the use of the two tagging agents, despite the tendency toward better tagging with the use of the 4.6% w/v barium suspension.
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http://dx.doi.org/10.3348/kjr.2009.10.1.25DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2647168PMC
April 2009

A case of primary paraganglioma that arose in the pancreas: the Color Doppler ultrasonography and dynamic CT features.

Korean J Radiol 2008 Jul;9 Suppl:S18-21

Department of Radiology & Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Paragangliomas rarely originate from the pancreas and they are characterized on imaging studies as well-marginated, hypervascular masses with cystic areas. We herein report on a case report of pancreatic paraganglioma in a 57-year-old woman, which was confirmed on pathology. Color Doppler ultrasonography and dynamic CT demonstrated a well-demarcated, extremely hypervascular mass with prominent intratumoral vessels and early contrast filling of the draining veins from the mass. Endoscopic retrograde cholangiopancreatography showed that the main pancreatic duct was displaced and mildly dilated.
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http://dx.doi.org/10.3348/kjr.2008.9.s.s18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627194PMC
July 2008

Usefulness of computed tomography in differentiating transmural infarction from nontransmural ischemia of the small intestine in patients with acute mesenteric venous thrombosis.

J Comput Assist Tomogr 2008 Sep-Oct;32(5):730-7

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Objective: To determine computed tomographic findings that are helpful in differentiating transmural infarction from nontransmural ischemia in patients with mesenteric ischemia secondary to acute mesenteric venous thrombosis (MVT).

Methods: Twenty-seven patients with symptomatic acute MVT were categorized into 2 groups: a transmural infarction (n = 13) and a nontransmural ischemia group (n = 14) based on findings at surgery and clinical follow-up. Computed tomographic scans were retrospectively reviewed by the consensus of 2 radiologists. Computed tomographic findings were compared between the 2 groups using the Fisher exact and the independent sample t test. Multifactorial logistic regression analysis was performed to determine the best predictors for differentiating transmural infarction from nontransmural ischemia.

Results: Bowel segments with homogeneous enhancement (P = 0.001), decreased enhancement (P = 0.001), and indistinct outer margins (P = 0.006) were significantly more common in the transmural infarction group than in the nontransmural ischemia group. The differences in maximal lumen diameter (P = 0.027), extent of mesenteric haziness (P = 0.018), and amount of ascites (P = 0.035) were significant between the 2 groups. On multifactorial logistic regression analysis, decreased enhancement (P = 0.007) and maximal lumen diameter (P = 0.039) were independent significant variables in differentiating transmural infarction from nontransmural ischemia.

Conclusions: In patients with acute MVT, computed tomography is valuable in differentiating transmural infarction from nontransmural ischemia.
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http://dx.doi.org/10.1097/RCT.0b013e318159f135DOI Listing
October 2008

Temporary metallic stent placement in the treatment of refractory benign esophageal strictures: results and factors associated with outcome in 55 patients.

Eur Radiol 2009 Feb 26;19(2):384-90. Epub 2008 Aug 26.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-2dong, Songpa-gu, Seoul, 138-736, Korea.

The purpose of this study was to evaluate the effectiveness of temporary metallic stenting in 55 patients with treatment-resistant benign esophageal strictures and to identify factors associated with clinical outcomes. Under fluoroscopic guidance, covered retrievable stents were placed in 55 patients with benign esophageal strictures and were removed with retrieval hook 1 week to 6 months after placement. Stent placement was successful in all patients, and the mean dysphagia score was reduced from 2.8 to 1.3 (p<0.001). The most common complications were tissue hyperproliferation (31%), severe pain (24%), and stent migration (25%). During follow-up (mean: 38 months), recurrence of the stricture necessitating balloon dilation was seen in 38 (69%) of 55 patients. Maintained patency rates after temporary stenting at 1, 3, and 6 months and 1, 2, and 4 years were 58%, 43%, 38%, 33%, 26%, and 21%, respectively. In multivariate analysis, length (p=0.003) of the stricture was the only significant factor associated with maintained patency after temporary stenting. In conclusion, temporary metallic stenting for refractory benign esophageal strictures may be effective during the period of stent placement, but is disadvantaged by the high recurrence rates after stent removal, particularly in patients with a long length of stricture (>7 cm).
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http://dx.doi.org/10.1007/s00330-008-1151-2DOI Listing
February 2009

Biliary tract depiction in living potential liver donors at 3.0-T magnetic resonance cholangiography.

Invest Radiol 2008 Aug;43(8):594-602

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Objectives: To prospectively evaluate accuracy of biliary anatomy depiction and quality of biliary tract visualization of magnetic resonance cholangiography (MRC) at 3.0 T in living potential liver donors (LPLDs).

Materials And Methods: Our institutional review board approved this study and did not require patient's informed consent. Thirty-three LPLDs underwent MRC at 3.0-T magnetic resonance and intraoperative cholangiography as the reference standard. MRC protocol included breath-hold rapid acquisition with relaxation enhancement (RARE) and respiratory-triggered 3-dimensional turbo spin-echo (TSE) T2-weighted sequence. Two readers independently analyzed 2 MRC image sets with a 2-week interval for delineating biliary anatomy and scoring degree of visualization of biliary branches with a 4-point scale, and recorded the number of visible third-order branches. One month later, both readers independently evaluated combined both MRC image set to assess biliary anatomy.

Results: Biliary anatomy was correctly depicted by RARE sequence in 28 (84.8%) and 26 LPLDs (78.8%), by TSE sequence in 27 (81.8%) and 26 (78.8%), and by combined both sequences in 27 (81.8%) and 28 (84.8%), for readers 1 and 2, respectively. The mean second-order branch visualization scores for 2 readers were significantly higher for RARE images than for TSE (2.23 vs. 1.68, P = 0.02; 2.05 vs. 1.54, P = 0.02, respectively). The mean numbers of visible third-order branches were significantly higher for RARE images than TSE for both readers (4.36 vs. 3.04, P = 0.03; 4.72 vs. 3.32, P = 0.03, respectively).

Conclusions: In LPLDs, MRC at 3.0 T with both RARE and TSE sequences enables accurate depiction of biliary anatomy. RARE sequence more clearly visualizes second- and third-order biliary branches than TSE sequence.
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http://dx.doi.org/10.1097/RLI.0b013e31817e9b52DOI Listing
August 2008

The one-anchor technique of gastropexy for percutaneous radiologic gastrostomy: results of 248 consecutive procedures.

J Vasc Interv Radiol 2008 Jul 27;19(7):1048-53. Epub 2008 May 27.

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Pungnap-2dong, Songpa-gu, Seoul 138-736, Korea.

Purpose: To evaluate the safety and efficacy of the one-anchor technique of gastropexy for percutaneous radiologic gastrostomy (PRG).

Materials And Methods: A total of 248 PRG procedures with the one-anchor technique were attempted in 242 consecutive patients between January 2000 and June 2006. For gastropexy, a single anchor was used and gastrostomy tube placement was performed through the same tract of the anchor with a 10-16-F Wills-Oglesby gastrostomy catheter. Technical success, complications, and anchor dislodgments were evaluated by means of review of imaging studies and patient medical records.

Results: Among 248 procedures, PRG with the one-anchor technique was performed successfully in 247 procedures, with one procedural failure (99.6% successful placement rate). Fourteen-day follow-up data were available for 216 patients (87%). There were 11 major complications (5.1%), including peritonitis (n = 5), bleeding (n = 4), infection requiring tube removal (n = 1), and gastrocolic fistula (n = 1); and 31 minor complications (14.4%), including tube malfunction (ie, dislodgment, occlusion, breakage; n = 26), oozing (n = 4), and infection (n = 1). There were 25 anchor dislodgments, including breakdown of the string of the anchor during the procedure (n = 5), early release of the anchor within 1 week (n = 9), migration into the peritoneal space (n = 8), and expulsion out of the body (n = 3). Four major complications and one failure were directly related to anchor dislodgment.

Conclusions: PRG with the one-anchor technique is a feasible procedure. However, anchor dislodgments are relatively common, and these are related to major complications such as peritonitis and bleeding.
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http://dx.doi.org/10.1016/j.jvir.2008.03.021DOI Listing
July 2008

Usefulness of multifunctional gastrointestinal coil catheter for colorectal stent placement.

Eur Radiol 2008 Nov 4;18(11):2530-4. Epub 2008 Jun 4.

Asan Medical Center, Radiology and Research Institute of Radiology, Seoul, South Korea.

The purpose of this study was to evaluate the usefulness of a multifunctional gastrointestinal coil catheter for stent placement in 98 patients with colorectal strictures. The catheter was used in 98 consecutive patients for stent placement in the rectum (n = 24), recto-sigmoid (n = 13), sigmoid (n = 38), descending (n = 6), transverse (n = 11), splenic flexure (n = 3), hepatic flexure (n = 2), and ascending (n = 1) colon. The catheter was made of a stainless steel coil (1.3 mm in inner diameter), a 0.4-mm nitinol wire, a polyolefin tube, and a hemostasis valve. Usefulness of the catheter was evaluated depending on whether the catheter could pass a stricture over a guide wire and whether measurement of the stricture length was possible. The passage of the catheter over a guide wire beyond the stricture was technically successful and well tolerated in 93 (94.9%) of 98 patients. In the failed five patients, it was not possible to negotiate the guide wire due to presence of nearly complete small bowel obstruction. The average length of stricture was 6.15 cm (range, 3 cm to 20 cm) in patients with the colorectal stricture. There were no procedure-related complications. In conclusion, the multifunctional coil catheter seems to be useful in colorectal stent placement.
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http://dx.doi.org/10.1007/s00330-008-1042-6DOI Listing
November 2008

Automated carbon dioxide insufflation for CT colonography: effectiveness of colonic distention in cancer patients with severe luminal narrowing.

AJR Am J Roentgenol 2008 Mar;190(3):698-706

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-Dong, Songpa-Gu, 138-040 Seoul, Korea.

Objective: The objective of our study was to determine the effectiveness of automated CO2 insufflation in colonic distention for CT colonography (CTC) in patients with severe luminal narrowing by colorectal cancer and preliminarily evaluate its safety performed shortly after colonoscopic polypectomy or biopsy.

Materials And Methods: Seventy-four patients were examined with colonoscopy and subsequent CTC (time interval, 0-8 days) using automated CO2 insufflation. Thirty-six patients whose colonoscopy was incomplete due to severe luminal narrowing by cancer that prevented colonoscope passage constituted the stenotic group. The remaining 38 patients constituted the nonstenotic group. Colonic distention was graded by two experienced readers from 1 (worst) to 4 (best) and compared between the two groups. Clinical data and CT images were analyzed for the occurrence of colonic perforation.

Results: Distention was not significantly different between the stenotic and nonstenotic groups in any colonic segments in both supine and prone positions. The mean distention grade +/- SD of the colonic segments proximal to the luminal narrowing in the stenotic group (n = 143 segments) was 3.7 +/- 0.7 and 3.8 +/- 0.7 for the supine and prone positions, respectively. Colonic perforation was not noted in any of the 74 patients, including 65 patients who underwent CTC within 24 hours after colonoscopy (62 snare polypectomies, two polypectomies using biopsy forceps, 63 routine mucosal biopsies).

Conclusion: Automated pressure-controlled CO2 insufflation is as efficient in colonic distention for CTC in colorectal cancer patients with severe luminal narrowing as it is in patients without severe luminal narrowing.
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http://dx.doi.org/10.2214/AJR.07.2156DOI Listing
March 2008

Metallic stent placement in patients with recurrent cancer after gastrojejunostomy.

J Vasc Interv Radiol 2007 Dec;18(12):1538-46

Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap-2dong, Songpa-gu, Seoul, Republic of Korea.

Purpose: To assess the technical feasibility and clinical effectiveness of placement of expandable metallic stents in patients with recurrent cancer after a gastrojejunostomy.

Materials And Methods: Data from 39 consecutive patients who had undergone metallic stent placement for recurrent malignant obstruction after a gastrojejunostomy were retrospectively analyzed. Thirty patients underwent a distal gastrectomy with a gastrojejunostomy with (n=10) or without (n=20) jejunojejunostomy, two patients underwent distal gastrectomy with a Roux-en-Y gastrojejunostomy, and seven patients underwent a palliative gastrojejunostomy with (n=5) or without (n=2) jejunojejunostomy. A total of 57 metallic stents were used in this study: four bare stents, 29 partially covered stents, and 24 fully covered stents. Types of obstruction were classified into 12 patterns and types of stent placement were classified into 16 patterns.

Results: Stent placement was technically successful in all patients. After stent placement, 35 of the 39 patients (90%) experienced improvement of their symptoms, two showed no change, and the remaining two showed aggravation of symptoms as a result of faulty stent placement. Two patients treated with stent placement only in the afferent loop died of aspiration pneumonia. In one of two patients who underwent stent placement according to pattern 6, afferent loop syndrome occurred 10 days after stent placement and was treated by percutaneous pigtail catheter drainage. Stent migration occurred in four of 24 fully covered stents, but in none of the bare or partially covered stents. Tumor ingrowth occurred in one of four bare stents, tumor overgrowth in one of 29 partially covered stents, and mucosal prolapse in one of 24 fully covered stents; all were treated with a second stent placement.

Conclusions: Placement of expandable metallic stents in patients with recurrent cancer after a gastrojejunostomy seems to be feasible and effective, but accurate knowledge of the type of surgical procedure performed and determination of the pattern of tumor recurrence are important for successful stent placement.
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http://dx.doi.org/10.1016/j.jvir.2007.08.037DOI Listing
December 2007

Linear polyp measurement at CT colonography: 3D endoluminal measurement with optimized surface-rendering threshold value and automated measurement.

Radiology 2008 Jan 21;246(1):157-67. Epub 2007 Nov 21.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-Dong, Songpa-Gu, Seoul 138-040, Korea.

Purpose: To determine the optimal surface-rendering threshold value for three-dimensional (3D) endoluminal computed tomographic (CT) colonographic images for accurate manual polyp measurement, with direct measurement of simulated polyps as the reference standard, and to assess the agreement between manual 3D measurements and automated measurements.

Materials And Methods: Institutional review board approval was not required for the experimental study with pig colons obtained at an abattoir but was obtained for the use of patient data, with waiver of informed consent. Eighty-six simulated polyps (reference size, 3-15 mm) and 14 human polyps (approximate size, 5-20 mm) were included. Automated polyp measurements and manual measurements with endoluminal views that were surface rendered at threshold values of -800, -700, -600, and -500 HU were performed by one observer. Agreement between CT colonographic measurements and reference sizes and between manual and automated measurements were assessed by using the Bland-Altman method.

Results: For simulated polyps, mean measurement difference between the observed size and reference size was 0.86 mm (95% limits of agreement: -0.52 mm, 2.24 mm), 0.55 mm (95% limits of agreement: -0.75 mm, 1.85 mm), 0.20 mm (95% limits of agreement: -1.11 mm, 1.50 mm), and -0.08 mm (95% limits of agreement: -1.43 mm, 1.27 mm) for -800, -700, -600, and -500 HU, respectively. Mean measurement difference was 0.09 mm (95% limits of agreement: -1.49 mm, 1.67 mm) for automated measurement. Manual polyp size at -500 HU (P = .277) and automated polyp size (P = .288) were not significantly different from reference size. For human polyps, 10 polyps, excluding four lesions that were large, lobulated, or located adjacent to an edge of the haustral fold, showed accurate automated demarcation of lesion boundaries. Automated measurements of the 10 polyps showed the closest agreement with manual measurements at -500 HU.

Conclusion: The optimal surface-rendering threshold value for accurate polyp measurement is approximately -500 HU. Automated measurements agree closely with manual measurements at the optimal threshold value for well-circumscribed smooth rounded polyps.
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http://dx.doi.org/10.1148/radiol.2453061930DOI Listing
January 2008

Management of recurrent urethral strictures with covered retrievable expandable nitinol stents: long-term results.

AJR Am J Roentgenol 2007 Dec;189(6):1517-22

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-2 Dong, Songpa-Gu, 138-736 Seoul, Korea.

Objective: The purpose of this study was to evaluate the long-term clinical efficacy of temporary placement of covered retrievable stents in the management of recurrent urethral strictures.

Materials And Methods: During the period December 1998-December 2005, 32 men and one adolescent boy (mean age, 48.6 years; range, 16-73 years) with recurrent urethral strictures underwent fluoroscopically guided insertion of a total of 68 stents. Patients without complications underwent elective stent removal 2 or 4 months after stent insertion. Rates of clinical success (long-term clinical and radiographic resolution of urethral strictures) were assessed. The Mann-Whitney U test was used to compare the duration of stent placement in patients with long-term clinical resolution with that in patients with stricture relapse.

Results: Clinical success was achieved in 18 (55%) of the 33 patients. The mean duration of stent placement in patients with clinical success was significantly different from that in patients who had recurrences (p < 0.0001). Stricture relapse did not occur in only four (20%) of 20 cases of stent placement for 2 months. All 14 stent placements lasting at least 4 months resulted in long-term resolution after a mean follow-up period of 3.6 years. The most common complications necessitating early stent removal were stent migration (33.8% of stents) and tissue hyperplasia (20.6% of stents).

Conclusion: Placement of a covered retrievable stent for a minimum of 4 months is effective in inducing long-term resolution of refractory urethral strictures. Stent migration remains the largest obstacle in achieving adequate duration of stent placement.
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http://dx.doi.org/10.2214/AJR.07.2149DOI Listing
December 2007

Abdominal extrapancreatic lesions associated with autoimmune pancreatitis: radiological findings and changes after therapy.

Eur J Radiol 2008 Sep 27;67(3):497-507. Epub 2007 Sep 27.

Department of Radiology & Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.

Purpose: To evaluate imaging findings of abdominal extrapancreatic lesions associated with autoimmune pancreatitis (AIP) and changes after steroid therapy.

Methods And Materials: This study included nine AIP patients with abdominal extrapancreatic lesions, which were determined by retrospective radiological review. CT (initial and follow-up, n=9) and MR imaging (initial, n=5) were reviewed by two radiologists in consensus to determine imaging characteristics (i.e., size, number, attenuation or signal intensity, and contrast enhancement of the lesions, and the presence of overlying capsule retraction) and evaluate changes with steroid therapy of abdominal extrapancreatic lesions associated with AIP.

Results: The most common abdominal extrapancreatic lesion associated with AIP was retroperitoneal fibrosis (RPF) in six patients. In five patients, CT and MR imaging revealed single or multiple, round- or wedge-shaped, hypoattenuating or hypointense, enhancing lesions in the renal cortex or pelvis. Other lesions included a geographic, ill-defined, hypoattenuating lesion with or without overlying capsule retraction in the liver in two and bile duct dilatation with or without bile duct wall thickening in four. Over a follow-up period of 6-81 months, CT exams of eight patients demonstrated partial or complete improvement of the abdominal extrapancreatic lesions, albeit their improvement in general lagged behind that of the pancreatic lesion.

Conclusion: On CT or MR imaging, the abdominal extrapancreatic lesions associated with AIP are various in the retroperitoneum, liver, kidneys and bile ducts, and are reversible with steroid therapy.
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http://dx.doi.org/10.1016/j.ejrad.2007.08.018DOI Listing
September 2008

CT colonography for follow-up after surgery for colorectal cancer.

AJR Am J Roentgenol 2007 Aug;189(2):283-9

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-Dong, Songpa-Gu, Seoul 138-736, Korea.

Objective: The purpose of this article is to discuss the CT colonography (CTC) findings and the role of CTC for follow-up after curative surgery for colorectal cancer.

Conclusion: Contrast-enhanced CTC can be effective for surveillance for colorectal cancer recurrence after curative surgery because it enables simultaneous evaluation of distant abdominal metastasis, pericolic recurrence, intraluminal recurrence, and metachronous lesions. The appearances of anastomotic recurrences at CTC overlap with those of more common inflammatory polyps and rare benign ulcers.
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http://dx.doi.org/10.2214/AJR.07.2305DOI Listing
August 2007

Unenhanced CT for assessment of macrovesicular hepatic steatosis in living liver donors: comparison of visual grading with liver attenuation index.

Radiology 2007 Aug;244(2):479-85

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, Korea.

Purpose: To retrospectively compare the accuracy of visual grading and the liver attenuation index in the computed tomographic (CT) diagnosis of 30% or higher macrovesicular steatosis in living hepatic donors, by using histologic analysis as the reference standard.

Materials And Methods: Institutional review board approval was obtained with waiver of informed consent. Of 703 consecutive hepatic donor candidates, 24 patients (22 men and two women; mean age +/- standard deviation, 36.3 years +/- 9.7) who had 30% or higher macrovesicular steatosis at histologic analysis and same-day CT with subsequent needle biopsy in the right hepatic lobe (at least two samples per patient) were evaluated. An age- and sex-matched control group of 24 subjects included those who had less than 30% macrovesicular steatosis but otherwise met the same criteria as the patient group. A diagnostically difficult setting was made by selecting those with the highest degree of macrovesicular steatosis when there were multiple control subjects matched for a particular subject in the patient group. Two independent radiologists assessed steatosis of the right hepatic lobe by using two methods: a five-point visual grading system that used attenuation comparison between the liver and hepatic vessels and the liver attenuation index (CT(L-S)), defined as hepatic attenuation minus splenic attenuation and calculated with region of interest measurements of hepatic attenuation. Interobserver agreement was assessed. Accuracy in the diagnosis of 30% or higher macrovesicular steatosis was compared by using a multireader, multicase receiver operating characteristic (ROC) analysis.

Results: For visual grading, kappa = 0.905 (95% confidence interval [CI]: 0.834, 0.976). Intraclass correlation coefficient for CT(L-S) was 0.962 (95% CI: 0.893, 0.983). The area under the ROC curve of visual grading and CT(L-S) were 0.927 (95% CI: 0.822, 1) and 0.929 (95% CI: 0.874, 0.983), respectively, indicating no statistically significant difference (P = .975).

Conclusion: Both visual grading and CT(L-S) are highly reliable and similarly accurate in the diagnosis of 30% or higher macrovesicular steatosis in living hepatic donor candidates.
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http://dx.doi.org/10.1148/radiol.2442061177DOI Listing
August 2007

Covered metallic stent placement in the management of cervical esophageal strictures.

J Vasc Interv Radiol 2007 Jul;18(7):888-95

Department of Radiology, Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Songpa-Gu, Seoul, Korea.

Purpose: To describe the authors' experience with self-expandable covered metallic stents in 16 patients with malignant and benign cervical esophageal strictures.

Materials And Methods: Sixteen expandable covered metallic stents were placed with fluoroscopic guidance in 16 patients (14 men, two women; mean age, 60 years; age range, 26-75 years) with malignant and benign strictures of the cervical esophagus. The causes of strictures were ingestion of corrosive agents (n = 3), biopsy-proved squamous cell carcinoma (n = 12), and postsurgical scarring (n = 1). The mean dysphagia scores at presentation were compared with those after stent placement by using the Wilcoxon signed rank test.

Results: Stent placement was technically successful in all patients. The reduction in the mean dysphagia score after stent placement was statistically significant (P = .0327). All patients complained of mild to severe foreign body sensation, with four reporting severe pain necessitating immediate stent removal. With the exception of one patient with limited follow-up, complications requiring intervention occurred in all patients, including migration in nine patients and tissue hyperproliferation in two. Of the 12 patients with a malignant stricture of the esophagus, four patients eventually underwent gastrostomy for the placement of a feeding tube and one patient underwent surgery. All four patients with a benign cervical stricture failed to achieve long-lasting improvement with temporary stent placement.

Conclusions: Although the placement of covered metallic stents in the cervical esophagus provides adequate initial palliation, it is associated with poor patient tolerance and a high complication rate.
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http://dx.doi.org/10.1016/j.jvir.2007.04.017DOI Listing
July 2007

Colorectal polyps on portal phase contrast-enhanced CT colonography: lesion attenuation and distinction from tagged feces.

AJR Am J Roentgenol 2007 Jul;189(1):35-40

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap2-Dong, Songpa-Gu, Seoul 138-040, Korea.

Objective: The purpose of our study was to determine the attenuation of colorectal polyps on portal phase contrast-enhanced CT colonography (CTC) and evaluate whether enhanced polyps can be clearly distinguished from tagged feces during CTC review.

Materials And Methods: Our institutional review board approved this study and waived patient informed consent. Forty-eight colonoscopy-proven polyps (6-20 mm) and 41 polypoid tagged feces (6-19 mm) were selected from contrast-enhanced CTC performed without (n = 37 examinations) and with (n = 10 examinations) fecal tagging, respectively. Scanning was performed 72 seconds after i.v. injection of 150 mL of contrast material at a rate of 2.5 mL/s. Fecal tagging consisted of three doses of 200 mL of 5% weight/volume (w/v) barium sulfate suspension taken at each meal the day before CTC. Attenuation of the polyps and tagged feces was measured. Four independent blinded radiologists reviewed the polyps and tagged feces at both wide (width, 1,500 H; level -400 H) and soft-tissue (width, 400 H; level, 20 H) window settings to distinguish them by using subjective visual assessment.

Results: Polyp attenuation on the portal phase was not correlated with size (R = -0.003; p = 0.99) and was not different between histologic types (p = 0.884). Enhanced polyps (mean +/- SD, 119.9 +/- 25.3 H; range, 50-173 H) showed significantly lower attenuation than did tagged feces (1,521.4 +/- 683.6 H; range, 495-2,683 H) without any overlap (p < 0.0005). An 8-mm sessile adenomatous polyp was misinterpreted as tagged feces by one reviewer. The rest of the lesions were correctly interpreted by all reviewers, resulting in high interobserver agreement (kappa value, 0.988).

Conclusion: Polyp attenuation on portal phase contrast-enhanced CTC ranges from 50 to 173 H. Contrast-enhanced polyps are clearly and consistently distinguished from barium-tagged polypoid feces.
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http://dx.doi.org/10.2214/AJR.07.2076DOI Listing
July 2007

Malignant rectal polyp overlooked on CT colonography because of retention balloon: opposing crescent appearance as sign of compressed polyp.

AJR Am J Roentgenol 2007 Jul;189(1):W1-3

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-Dong, Songpa-Gu, 138-040 Seoul, Korea.

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http://dx.doi.org/10.2214/AJR.05.1643DOI Listing
July 2007

Efficacy of mitomycin-C irrigation after balloon dacryocystoplasty.

J Vasc Interv Radiol 2007 Jun;18(6):757-62

Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1, Pungnap-2dong, Songpa-gu, Seoul 138-736, Korea.

Purpose: To evaluate the safety and efficacy of mitomycin-C irrigation after balloon dacryocystoplasty in the treatment of epiphora caused by obstruction of the lacrimal system.

Materials And Methods: Thirty-five lacrimal systems in 33 patients with obstruction of the lacrimal system were assigned to one of two groups: 17 lacrimal systems were irrigated with mitomycin-C after balloon dacryocystoplasty (mytomycin-C group), and 18 were not irrigated with mitomycin-C after balloon dacryocystoplasty (non-mitomycin-C group). In the mitomycin-C group, the lacrimal systems were irrigated with 0.2 mg/mL mitomycin-C via the inferior lacrimal punctum in three different sessions: immediately, 1 week, and 1 month after balloon dacryocystoplasty. The cumulative patency rates after balloon dacryocystoplasty were calculated by using the Kaplan-Meier method and were compared between the two groups with use of the log-rank test.

Results: Balloon dacryocystoplasty and subsequent mitomycin-C irrigation were technically successful in all lacrimal systems. There were no side effects or complications associated with mitomycin-C use. The cumulative patency rate in the mitomycin-C group was significantly higher than that in the non-mitomycin-C group after balloon dacryocystoplasty (P = .0150, log-rank test).

Conclusions: Mitomycin-C irrigation is safe and effective in increasing the patency rate of the lacrimal system after balloon dacryocystoplasty.
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http://dx.doi.org/10.1016/j.jvir.2007.04.001DOI Listing
June 2007

Imaging findings of leukemic involvement of the pancreaticobiliary system in adults.

AJR Am J Roentgenol 2007 Jun;188(6):1589-95

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-2dong, Songpa-gu, Seoul 138-736, Korea.

Objective: Our objective was to review the imaging findings of patients with leukemic involvement of the pancreaticobiliary system in adults.

Conclusion: Pancreatic myeloid and lymphoid leukemia show single or multiple mass lesions of homogeneous low attenuation and poor contrast enhancement on CT that is radiographically indistinguishable from that of pancreatic lymphoma. Although more cases are needed for confirmation, leukemic infiltration of the biliary tract is characterized by wall thickening of the bile duct with minimal contrast enhancement--a feature that may be helpful in differentiating it from infiltrating hilar or extrahepatic cholangiocarcinoma.
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http://dx.doi.org/10.2214/AJR.06.0245DOI Listing
June 2007

Polyp measurement reliability, accuracy, and discrepancy: optical colonoscopy versus CT colonography with pig colonic specimens.

Radiology 2007 Jul 16;244(1):157-64. Epub 2007 May 16.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Purpose: To prospectively evaluate the reliability and accuracy of optical colonoscopy and computed tomographic (CT) colonography in polyp measurement, by using direct measurement as the reference standard, and to understand the basis for measurement discrepancy between both modalities.

Materials And Methods: Eighty-six simulated polyps that ranged from 3 to 15 mm were constructed by using pig colons obtained from an abattoir. Approval of the animal care and use committee for the study was not required. CT colonographic measurement was performed by two independent radiologists by using two-dimensional (2D) optimized multiplanar reformatted planes and three-dimensional (3D) endoluminal views. Optical colonoscopic measurement was performed by two independent gastroenterologists by using open biopsy forceps. Interobserver agreement, measurement error, measurement discrepancy defined as the result of subtracting the optical colonoscopic measurement from the CT colonographic measurement, and false-mismatch (ie, designation of matched polyps as mismatched between both modalities) rates according to different matching criteria were analyzed.

Results: Intraclass correlation coefficients were 0.879 (95% confidence interval: 0.780, 0.930) for optical colonoscopy, 0.979 (95% confidence interval: 0.956, 0.989) for 2D CT colonography, and 0.985 (95% confidence interval: 0.976, 0.990) for 3D CT colonography. The mean standardized polyp size +/- standard deviation for each observer was 76.3% +/- 14.7 and 85.3% +/- 18.8 for optical colonoscopy, 104.6% +/- 11.6 and 101.6% +/- 10.1 for 2D CT colonography, and 114% +/- 12.4 and 113.4% +/- 13.2 for 3D CT colonography. These values indicated that there was a statistically significant difference among the methods (P<.001). Measurement discrepancy was not proportional to polyp size. A percentage-of-error criterion showed increasing false-mismatch rates with decreasing polyp size, whereas a fixed margin-of-error criterion resulted in more uniform false-mismatch rates across polyp size.

Conclusion: CT colonography is more reliable and accurate than optical colonoscopy for polyp measurement. A fixed margin-of-error criterion is better than a percentage-of-error criterion for polyp matching between CT colonography and optical colonoscopy with open biopsy forceps.
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http://dx.doi.org/10.1148/radiol.2441060794DOI Listing
July 2007

Efficacy of mitomycin C irrigation after removal of an occluded nasolacrimal stent.

J Vasc Interv Radiol 2007 Apr;18(4):519-25

Department of Radiology and Research, Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1, Pungnap-2dong, Songpa-gu, Seoul 138-736, Korea.

Purpose: Mitomycin C (MMC) acts as a potent fibroblastic inhibitor, and topical application of MMC is effective in preventing scar formation. The purpose of this study was to evaluate the safety and efficacy of MMC irrigation after removal of an occluded nasolacrimal stent from the lacrimal system.

Materials And Methods: A total of 57 lacrimal systems after removal of an occluded stent were assigned to one of two groups: 23 lacrimal systems were irrigated with MMC after stent removal (MMC group), and 34 lacrimal systems were not irrigated with MMC after stent removal (non-MMC group). In the MMC group, the lacrimal systems were irrigated with 0.2 mg/mL MMC through the inferior lacrimal punctum for 3 minutes in three different sessions: immediately, 1 week, and 1 month after stent removal. The mean and cumulative patency rates after stent removal were calculated using the Kaplan-Meier method and were compared between the two groups using the log-rank test.

Results: Stent removal and MMC irrigation were technically successful in all lacrimal systems. There were no side effects or complications associated with MMC use. The mean patency rate after stent removal was higher in the MMC group than that of the non-MMC group: 10.5 months (95% CI: 7.04, 13.91) versus 4.5 months (95% CI: 2.40, 6.63), respectively. There was a statistically significant difference in the cumulative patency rates after stent removal between the two groups (P = .005, log-rank test).

Conclusions: Mitomycin C irrigation is safe and effective in increasing patency rate of lacrimal systems after removal of an occluded nasolacrimal stent.
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http://dx.doi.org/10.1016/j.jvir.2007.01.016DOI Listing
April 2007

Granulocytic sarcoma of bowel: CT findings.

Radiology 2007 Jun 19;243(3):752-9. Epub 2007 Apr 19.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul 138-736, Korea.

Purpose: To evaluate retrospectively the computed tomographic (CT) findings of granulocytic sarcoma of the bowel.

Materials And Methods: The institutional review boards of all participating institutions approved this study and waived the requirement for informed consent. CT scans were retrospectively reviewed in eight patients (seven men, one woman; age range, 23-71 years; mean age, 46 years) with pathologically proved granulocytic sarcoma of the small and/or large bowel. CT findings were evaluated with regard to the sites, morphologic characteristics, and contrast material enhancement patterns of the lesions, along with other ancillary findings (ie, peritoneal and mesenteric infiltration, ascites, lymphadenopathy, bowel perforation, and obstruction).

Results: Eight patients had a total of 13 lesions in the bowel (of which eight were pathologically proved), involving the duodenum (n=1), jejunum (n=2), ileum (n=5), sigmoid colon (n=1), and rectum (n=4); multifocal bowel lesions were noted in four patients. The lesion varied in shape, with wall thickening alone in three of 13 lesions, an intraluminal polypoid mass in four, an exophytic mass in one, and a combination of findings in five. Contrast material enhancement, relative to the back musculature, showed isoattenuation in seven lesions, hyperattenuation in four, and hypoattenuation in two. Five of eight patients had multiple peritoneal masses with diffuse mesenteric or peritoneal infiltration. Ascites was present in six of eight patients; lymphadenopathy (especially in the mesentery), in five; bowel perforation, in two; and bowel obstruction, in one.

Conclusion: Granulocytic sarcoma of the bowel is characterized by variability in shape and contrast enhancement and has a high predilection for mesenteric and peritoneal spread.
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http://dx.doi.org/10.1148/radiol.2433060747DOI Listing
June 2007

The diagnostic criteria for autoimmune chronic pancreatitis: it is time to make a consensus.

Pancreas 2007 Apr;34(3):279-86

Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Autoimmune chronic pancreatitis (AIP) is increasingly being recognized as a worldwide entity. In 2002, the Japan Pancreas Society published diagnostic criteria for AIP. Since then, increased attention toward this relatively new disease entity has enabled more cases of AIP to be correctly diagnosed, allowing for proper management and avoidance of surgery. Retrospective inclusion of previously unrecognized or misdiagnosed cases of AIP has revealed an increasing number of cases that are not in full accordance with the Japanese diagnostic criteria. As a result, some groups have developed and cited their own criteria in the reporting of AIP, and the Japan Pancreas Society criteria have also undergone revision recently. The absence of consistent and uniform criteria has made the comparison of different cases diagnosed under various guidelines difficult. In this review, we discuss and compare the 4 current diagnostic criteria, focusing on their own strength and weakness with the aim of providing a framework for the development of unified criteria that represent an international consensus.
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http://dx.doi.org/10.1097/MPA.0b013e31802eff5fDOI Listing
April 2007

Flat colorectal neoplasms: definition, importance, and visualization on CT colonography.

AJR Am J Roentgenol 2007 Apr;188(4):953-9

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-2dong, Songpa-gu, 138-736, Seoul, Korea.

Objective: We discuss the definition of flat colorectal neoplasms, their clinical importance, CT colonography (CTC) findings, techniques for better visualization on CTC, and diagnostic pitfalls of such lesions.

Conclusion: Flat lesions appear on CTC as plaque-shaped mucosal elevations with or without a central depression, thickened haustral folds, and nodular mucosal surfaces. The sensitivity and optimal techniques of CTC for the detection of flat lesions have not yet been established. Three-dimensional endoluminal fly-through may be helpful for lesion detection. Fecal tagging helps in the distinction of true flat lesions from feces. I.v. contrast enhancement and the review with intermediate soft-tissue window settings, although not routinely used for CTC, may also help lesion visualization.
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http://dx.doi.org/10.2214/AJR.06.0436DOI Listing
April 2007

Removal of a covered esophageal metallic stent 8 years after placement.

J Vasc Interv Radiol 2007 Feb;18(2):317-20

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-2dong, Songpa-gu, Seoul 138-736, Republic of Korea.

A covered expandable esophageal metallic stent was placed to treat a corrosive esophageal stricture that was refractory to repeated balloon dilations. The stent was removed 8 years after placement due to severe dysphagia. The stented esophageal area has since maintained long-term patency for 2 years. These results suggest the feasibility of removal of a metallic stent after long-term stent placement.
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http://dx.doi.org/10.1016/j.jvir.2006.11.004DOI Listing
February 2007

Functional MR imaging of prostate cancer.

Radiographics 2007 Jan-Feb;27(1):63-75; discussion 75-7

Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poong-nap-dong, Songpa-gu, Seoul 138-736, South Korea.

T2-weighted magnetic resonance (MR) imaging has been widely used for pretreatment work-up for prostate cancer, but its accuracy for the detection and localization of prostate cancer is unsatisfactory. To improve the utility of MR imaging for diagnostic evaluation, various other techniques may be used. Dynamic contrast material-enhanced MR imaging allows an assessment of parameters that are useful for differentiating cancer from normal tissue. The advantages of this technique include the direct depiction of tumor vascularity and, possibly, obviation of an endorectal coil; however, there also are disadvantages, such as limited visibility of cancer in the transitional zone. Diffusion-weighted imaging demonstrates the restriction of diffusion and the reduction of apparent diffusion coefficient values in cancerous tissue. This technique allows short acquisition time and provides high contrast resolution between cancer and normal tissue, but individual variability in apparent diffusion coefficient values may erode diagnostic performance. The accuracy of MR spectroscopy, which depicts a higher ratio of choline and creatine to citrate in cancerous tissue than in normal tissue, is generally accepted. The technique also allows detection of prostate cancer in the transitional zone. However, it requires a long acquisition time, does not directly depict the periprostatic area, and frequently is affected by artifacts. Thus, a comprehensive evaluation in which both functional and anatomic MR imaging techniques are used with an understanding of their particular advantages and disadvantages may help improve the accuracy of MR for detection and localization of prostate cancer.
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http://dx.doi.org/10.1148/rg.271065078DOI Listing
February 2007