Biomedical subjects

Joon Koo Han

Publications and source records attributed to Joon Koo Han.

At least 19 recordsLinked to original sources

PubMed2007

Esophageal varices in patients with cirrhosis: multidetector CT esophagography--comparison with endoscopy.

PURPOSE: To evaluate the use of multidetector computed tomographic (CT) esophagography to grade esophageal varices and differentiate between varices at low risk and those at high risk for bleeding, with endoscopy as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional review board; all subjects gave informed consent. Ninety patients with cirrhosis (65 men, 25 women; mean age, 54.8 years; range, 21-77 years) were prospectively enrolled and underwent endoscopy and CT esophagography. Esophageal varices were graded independently at endoscopy by two endoscopists. CT esophagograms were interpreted retrospectively with a four-point scale by two radiologists blinded to other findings. Interobserver agreement between each radiologist and endoscopist was determined; endoscopic and CT esophagographic grades of esophageal varices were correlated. Radiologist performance for differentiation between low- and high-risk varices for bleeding on the basis of morphology at endoscopy was evaluated with receiver operating characteristic analysis. Patients were interviewed to determine acceptance at both examinations. RESULTS: Thirty-seven of 90 patients had grade 0, 23 had grade 1, 18 had grade 2, and 12 had grade 3 esophageal varices. Thus, 60 patients were determined to be in a low-risk group and 30 in a high-risk group for variceal bleeding at endoscopy. There was almost perfect agreement in grading esophageal varices between endoscopists. There was close correlation (P < .001) and substantial agreement between endoscopic and CT esophagographic grades. Radiologist performance for differentiating between low- and high-risk varices was 0.931-0.958 (area under receiver operating characteristic curve). Patient interview results revealed that CT esophagography had better acceptance than did endoscopy (P < .001). CONCLUSION: Use of CT esophagography allows grading of esophageal varices and differentiation between low- and high-risk varices and shows better patient acceptance than does endoscopy.

Adult↗

PubMed2006

Preoperative evaluation of hepatic arterial and portal venous anatomy using the time resolved echo-shared MR angiographic technique in living liver donors.

The purpose of this study was to determine whether MR angiography utilizing the time resolved echo-shared angiographic technique (TREAT) can provide an effective assessment of the hepatic artery (HA) and portal vein (PV) in living donor candidates. MR angiography (MRA)was performed in 27 patients (23 men and 4 women; mean age, 31 years) by using TREAT. Two blinded radiologists evaluated HA anatomy, origin of segment IV feeding artery and PV anatomy in consensus. Qualitative evaluations of MRA images were performed using the following criteria: (a) overall image quality, (b) presence of artifacts, and (c) degree of venous contamination of the arterial phase. Using intraoperative findings as a standard of reference, the accuracy for the HA anatomy, origin of segment IV feeding artery and PV anatomy on TREAT-MRA were 93% (25/27), 85% (23/27), and 96% (26/27), respectively. Overall image qualities were as follows: excellent (n=22, 81%), good (n=4, 15%), and fair (n=1, 4%). Significant artifacts or venous contamination of the arterial phase images was not noted in any patient. TREAT-MRA can provide a complete evaluation of HA and PV anatomy during preoperative evaluation of living liver donors. Furthermore, it provides a more detailed anatomy of the HA without venous contamination.

Adolescent↗

PubMed2006

Intraarterial gene delivery in rabbit hepatic tumors: transfection with nonviral vector by using iodized oil emulsion.

PURPOSE: To evaluate the feasibility of an iodized oil emulsion that is used for the chemoembolization of hepatocellular carcinoma as a modifier of a nonviral gene transfer system for intraarterial gene delivery in experimentally induced hepatic tumors. MATERIALS AND METHODS: Experiments were performed in accordance with National Institutes of Health guidelines for the care and use of laboratory animals and were approved by the animal research committee at Seoul National University Hospital. VX2 carcinoma was implanted into the liver of 26 rabbits. Four nonviral gene transfer systems were prepared by using pCMV-luc+ as a reporter gene. The first system consisted of a DNA and polyethylenimine (PEI) complex (n = 7); the second, of a DNA and PEI complex mixed with iopamidol and iodized oil (n = 7); the third, of a DNA and PEI complex mixed with iopamidol (n = 7); and the fourth, of a DNA and PEI complex mixed with iodized oil (n = 5). For the DNA and PEI complex that was mixed with iopamidol and iodized oil, iopamidol was used to stabilize the emulsion. Twenty days after tumor implantation, intraarterial gene delivery was performed by selective catheterization of the hepatic artery. Rabbits were euthanized 24 hours after gene delivery. Luciferase activity was assayed in the tumor, left hepatic lobe, right hepatic lobe, and other organs and was statistically analyzed for comparison between complexes by using the Kruskal-Wallis test. RESULTS: Luciferase activity in the tumor was significantly higher for the group that received DNA, PEI, iopamidol, and iodized oil than for any other group (Kruskal-Wallis test, P < .05). Luciferase activity in the left hepatic lobe, right hepatic lobe, and other organs was not significantly different between complexes. Selective gene expression in tumor cells was confirmed by means of immunohistochemical analysis for luciferase. CONCLUSION: It is feasible to use an iodized oil emulsion system for the intratumoral transfection of nonviral vectors in experimentally induced hypervascular hepatic tumors.

Animals↗

PubMed2006

Three-dimensional MDCT imaging and CT esophagography for evaluation of esophageal tumors: preliminary study.

The aim of this study was to determine whether multidetector computed tomography (MDCT) imaging, including CT esophagography (CTE), can be used as a comprehensive imaging test for esophageal tumors. Twenty-three patients with esophageal neoplasms underwent MDCT with esophageal distension and endoscopy. Of them, 20 underwent barium study. Two radiologists independently reviewed MDCT images with 3D CT esophagography (CTE) including CT endoscopy and were asked to determine the presence of the esophageal lesions and characterize them using a five-point confidence scale. The radiologists' performance for the lesion detection and characterization was evaluated by receiver operating characteristic (ROC) analysis. They were also requested to determine the local staging of esophageal cancer, and the overall accuracies of MDCT for local staging were calculated. The ability of MDCT with CTE was also evaluated compared with conventional studies. CTE images successfully revealed 14 of 16 esophageal cancers and all seven submucosal tumors. Two esophageal cancers, both confined to the mucosal layer, were undetected. The Az values of the MDCT images were 0.954-0.957 for determining the presence of a lesion and 0.954-0.995 for differentiating between cancer and submucosal tumors. The overall accuracies for T and N staging were 42.9% and 85.7%, respectively. In 80% and 74% of cases, CTE gave similar or superior information to barium study and endoscopy, respectively. MDCT esophagography has the potential to serve as a comprehensive imaging modality for evaluating esophageal tumors as it provides accurate information regarding the detection and characterization of esophageal tumors as well as the similar information to conventional studies.

Adenocarcinoma↗

PubMed2006

The diagnostic value of multiplanar reconstruction on MDCT colonography for the preoperative staging of colorectal cancer.

The purpose of this study was to determine whether multiplanar reconstruction (MPR) images can improve the accuracy of MDCT-based colorectal cancer preoperative staging by receiver-operating characteristic (ROC) analysis. Fifty-five patients with colorectal cancer underwent contrast-enhanced CT colonography using an 8- or 16-row scanner. Two separate interval reviews of the axial MDCT datasets with/without MPR images (coronal and sagittal) were performed independently by two radiologists blinded to both the colonoscopic and histopathologic results. At each review session, the radiologists were asked to determine the colorectal cancer TNM stage within the context of differentiating < or =T3 from T4, N0 from > or =N1 and M0 from M1 using a five-point confidence scale. The radiologists' performance for staging the colorectal cancer using axial CT datasets with/without MPR images was evaluated using ROC analysis. Sensitivities, specificities and interobserver agreement were assessed. When MPR images were added, significant improvement was achieved by both radiologists for differentiating N0 from > or =N1 in terms of both A(Z) (0.651 to 0.769; 0.573 to 0.713) and specificity (26.7 to 69.2%; 23.1 to 76.9%) (P<0.05). For T staging, ROC analysis failed to show a significant improvement in terms of differentiating < or =T3 from T4 for either radiologist (P>0.05), but a significant improvement in the specificity (70 to 90%; 80 to 92%) was achieved by one radiologist (P<0.05). In terms of the M staging, a significant improvement in the Az (0.844 to 0.996) was observed for the combined interpretation of the axial and MPR images by one radiologist (P<0.05). Furthermore, substantial or almost perfect interobserver agreement was achieved for all TNM stagings for the combined interpretations (kappa=0.641-0.866), whereas only fair to substantial agreement was achieved for the axial images alone (kappa=0.337-0.707). In conclusion, the combined interpretation of the axial and MPR MDCT images significantly improved the local staging of colorectal cancer compared with assessments based on axial images alone.

Adult↗

PubMed2006

Hepatic macrosteatosis: predicting appropriateness of liver donation by using MR imaging--correlation with histopathologic findings.

PURPOSE: To retrospectively evaluate the diagnostic performance of magnetic resonance (MR) imaging in predicting the appropriateness of liver donation in potential living liver donors by using histopathologic results as the reference standard. MATERIALS AND METHODS: This study was approved by institutional review board; all patients gave informed consent for the use of MR data for future research. Fifty-seven potential liver donors (40 male, 17 female; age range, 17-57 years; mean age, 32 years) underwent dual-echo 1.5-T MR imaging. Two radiologists qualitatively graded each MR image, with consensus for disagreements. Livers were assigned one of three degrees of hepatic steatosis on the basis of changes in hepatic signal intensity (SI) between in-phase and opposed-phase images. For quantitative analysis, a third radiologist calculated mean hepatic and mean splenic SI by averaging 25 hepatic regions of interest and three splenic regions of interest. Relative SI decrease (RSID) in the liver on opposed-phase images compared with in-phase images was calculated. Linear regression analysis was used to correlate RSID with the degree of total steatosis, macrosteatosis, and microsteatosis. Diagnostic performance for predicting the appropriateness of liver donation was analyzed. RESULTS: Histologic findings of macrosteatosis resulted in 52 patients being categorized as appropriate donors, with the remaining five being categorized as inappropriate donors. RSID was correlated with total steatosis (r = 0.850). When the RSID criterion for inappropriateness of liver donation was set at 20%, the sensitivity, specificity, and accuracy were 100%, 92.3%, and 93%, respectively. When RSID was used, four livers that had been misclassified as inappropriate for transplantation were found to have microsteatosis of various degrees and a less than moderate degree of macrosteatosis at histologic analysis. Qualitative and quantitative analyses were comparably accurate. CONCLUSION: When an RSID criterion of less than 20% was used, dual-echo MR imaging facilitated the correct prediction of appropriateness of liver donation in 53 of 57 patients.

Adolescent↗

PubMed2006

Comparison of fundamental sonography, tissue-harmonic sonography, fundamental compound sonography, and tissue-harmonic compound sonography for focal hepatic lesions.

Image qualities of fundamental, tissue-harmonic, fundamental compound, and tissue-harmonic compound sonography for evaluating focal hepatic lesions were compared. Two radiologists, blinded to the type of techniques and to the final diagnosis, independently evaluated 384 images of 96 hepatic lesions: hemangiomas (n=35), hepatic cystic lesions (n=28), cirrhosis-related nodules (n=22), focal nodular hyperplasia (n=1), and metastases (n=10). All images were graded in terms of lesion conspicuity, margin sharpness, and overall image quality using a 4- or 5-point scale. In the cases of cystic lesions, posterior acoustic enhancement and internal artifacts were also analyzed. A Friedman test was used for multiple statistical comparisons of the four techniques for all parameters. Compound imaging was significantly superior to fundamental imaging regarding lesion conspicuity, margin sharpness, and overall quality (P<0.05). For posterior enhancement and internal artifacts within the cyst, harmonic ultrasonography (US) was significantly better than fundamental US (P<0.05). For evaluating focal hepatic lesions on US, compound imaging provided better lesion conspicuity, better margin sharpness, and better overall image quality than fundamental imaging did. Tissue harmonic imaging also provided better posterior enhancement and fewer internal artifacts of the cyst than fundamental imaging.

Adult↗

PubMed2006

Percutaneous drainage of postoperative abdominal abscess with limited accessibility: preexisting surgical drains as alternative access route.

PURPOSE: To retrospectively assess the effectiveness and safety of postoperative percutaneous drainage of abdominal abscesses with limited accessibility by using a preexisting surgical drain as an access route. MATERIALS AND METHODS: The study was approved by the institutional review board, and informed consent was not required. The authors reviewed the medical records of 92 patients (62 male, 30 female; median age, 59 years; age range, 3-79 years) with postoperative abdominal abscesses in whom percutaneous drainage was performed by using surgical drains as an access. Factors evaluated included the location and size of the lesion; time between surgery and the drainage procedure; distance between the lesion and surgical drain; presence of fistula; duration of drainage; type of surgical drain; size, type, and length of drainage catheter; and complications. Technical success was defined as adequate placement of a new drainage catheter into the target abscess. Midterm success was defined as avoidance of surgery or additional percutaneous drainage during the 6 months of follow-up. Univariate analysis and multiple logistic regression analysis were performed to determine factors that affected the technical or midterm success of the procedure. RESULTS: Of 92 postoperative abscesses for which the technique was attempted, 56 (61%) had a subphrenic location and 36 (39%) had a peripancreatic location. Technical success was achieved in 87 of the 92 patients (95%). Technical success was not significantly associated with any of the factors tested. Midterm success was achieved in 75 of the 87 patients (86%) in whom technical success was achieved. Midterm failure showed a statistically significant relationship with the presence of fistula (P = .04). No procedure-related complications were identified. CONCLUSION: Percutaneous drainage by using the surgical drain as an access route is an effective and safe alternative for draining postoperative abdominal abscesses that are less accessible with direct puncture..

Abdominal Abscess↗

PubMed2006

MDCT and superparamagnetic iron oxide (SPIO)-enhanced MR findings of intrapancreatic accessory spleen in seven patients.

The aim of this study is to retrospectively evaluate intrapancreatic accessory spleen (IPAS) with mutidetector computed tomography (MDCT) and superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) with emphasis on the role of SPIO-MRI for the diagnosis of IPAS. Seven patients (four men and three women; mean age, 50.7 years) with IPAS underwent quadriphasic MDCT and SPIO-enhanced MRI. IPAS was diagnosed histopathologically (n = 2) or by scintigraphy (n = 5). Two radiologists evaluated CT and MRI in consensus for the location and size of each lesion and compared its attenuation on CT and signal intensity (SI) on MRI with those of the pancreas and spleen. For quantitative analysis, another radiologist calculated the mean lesional, pancreatic, and splenic attenuations or SIs on MDCT or MRI in each patient. All lesions were located in the pancreatic tail. The average lesion size was 1.5 +/- 0.5 cm. All IPASs except one appeared high-attenuating to the pancreas and were isoattenuating to the spleen on all dynamic CT phases. The IPASs were hypointense and hyperintense compared with the pancreas on unenhanced T1- and T2-weighted images, respectively, and their SI was similar to that of the spleen. On SPIO-enhanced, T2-weighted images, a similar degree of signal drop to that of the spleen was noted in all lesions. The results of the quantitative analysis were compatible with those of the subjective analysis. In most IPASs, the attenuation on CT and SI on MRI were identical to those of the spleen, and on SPIO-enhanced MRI, the degree of the signal drop in all lesions was similar to that of the spleen.

Adult↗

PubMed2006

Preoperative assessment of resectability of hepatic hilar cholangiocarcinoma: combined CT and cholangiography with revised criteria.

PURPOSE: To retrospectively assess the accuracy of combined multiphasic computed tomography (CT) and direct cholangiography for evaluation of the resectability of hilar cholangiocarcinoma, on the basis of revised criteria for unresectability, by using surgery as the reference standard. MATERIALS AND METHODS: Institutional review board approval was obtained, and informed consent was waived. From 1998 to 2003, 55 patients (37 men, 18 women; mean age +/- standard deviation, 59 years +/- 12) with surgically proved hilar cholangiocarcinomas who underwent preoperative CT (single-detector row CT, n = 26; multi-detector row CT, n = 29) and cholangiography were included for study. The authors' revised criteria for unresectable tumor were contralateral hepatic artery invasion; main or contralateral portal vein invasion longer than 2 cm; biliary extension to the contralateral secondary confluence, farther than 2 cm from hepatic hilum; enlarged lymph nodes at the celiac, portacaval, and paraaortic area; and other ancillary findings. Tumor resectability based on these parameters was determined at imaging by two radiologists in consensus. Mann-Whitney U test and weighted kappa coefficient of agreement were used for accuracy determination. RESULTS: For depiction of portal vein invasion (in 26 patients), CT yielded an accuracy of 85.5%. Arterial invasion was found at surgery in 19 patients, with CT providing an accuracy of 92.7%. For prediction of node involvement (15 patients, 27%), CT yielded an accuracy of 83.6%. The extent of ductal involvement could be accurately predicted in 46 patients (84%) (weighted kappa = 0.767). In 30 of 42 patients with disease classified as resectable according to revised criteria, disease was found to be resectable at surgery (71.4% positive predictive value). In 11 of 13 patients with disease classified as unresectable according to revised criteria, unresectable disease was confirmed (84.6% negative predictive value). Overall accuracy of resectability was 74.5%. CONCLUSION: Combined interpretation of CT and direct cholangiographic images by using our revised criteria resulted in overall accuracy of 74.5% for prediction of resectability for hilar cholangiocarcinoma.

Adult↗

PubMed2006

State-of-the-art ultrasonography of hepatocellular carcinoma.

Over the last few decades sonographic techniques have progressed remarkably. Recent advances in ultrasonography include harmonics, real-time spatial compound imaging, adaptive image processing, 3D power Doppler imaging and contrast-enhanced gray-scale harmonic ultrasonography. These advances have had positive effects on the diagnosis of hepatocellular carcinomas and on the evaluation of their responses to therapy. In this article, we review recent sonographic advances for the diagnosis and treatment of hepatocellular carcinomas and its typical imaging features.

Carcinoma, Hepatocellular↗

PubMed2006

Intraoperative radiofrequency ablation using a loop internally cooled-perfusion electrode: in vitro and in vivo experiments.

OBJECTIVE: We sought to validate the efficiency of intraoperative radiofrequency ablation (RFA) using a prototype loop internally cooled-perfusion (LICP) electrode to induce coagulation in the subcapsular portion of the liver. MATERIALS AND METHODS: In in vitro experiments, 30 ablation regions were created using a 200-W generator and a LICP electrode featured simultaneous intraelectrode cooling and continuous flow of hypertonic saline along the shaft in explanted bovine liver. In the in vivo experiments, 26 ablation zones were created according to one of the five protocols in 10 dogs: group A, RFA using a cooled-tip electrode (n = 6); group B, RFA using a LICP electrode with 2 cm loop tip (n = 6); group C, RFA using a LICP electrode with a 3-cm loop tip (n = 6); group D, RFA using a cooled-tip electrode and Pringle maneuver (n = 4); and group E, RFA using a LICP electrode with 2 cm loop tip and Pringle maneuver (n = 4). The dimensions of the coagulation parameters were compared between the groups. RESULTS: In the in vitro experiments, RFA using a 2- or 3-cm diameter LICP electrode (3.6 +/- 0.3 cm, 3.4 +/- 0.5 cm, respectively) created deeper dimensions of coagulation than did a 4-cm electrode (2.3 +/- 0.2 cm; P < 0.05). In the in vivo experiments, the RFA using the LICP electrodes in porcine liver with normal perfusion induced wider but superficial ablation regions when compared to standard RFA using an internally cooled electrode (P < 0.05). However, using a Pringle maneuver, RFA with a LICP electrode created a larger volume of ablation area when compared to RFA using an internally cooled electrode with a similar range of axial diameter along the electrode axis: 30.0 +/- 6.1 cm3 (group D) versus 68.5 +/- 14.0 cm3 (group E; P < 0.05) CONCLUSIONS: Intraoperative RFA using the LICP electrode induced a well-defined semicircular coagulation with a 3.5-cm axial diameter in the subcapsular region of the liver. This device appears to be promising for the treatment of superficial tumors during intraoperative RFA.

Animals↗

PubMed2006

Preoperative evaluation of the hepatic vascular anatomy in living liver donors: comparison of CT angiography and MR angiography.

PURPOSE: To compare the diagnostic performance of CT angiography (CTA) and MR angiography (MRA) for preoperative hepatic vascular evaluation in living liver donors. MATERIALS AND METHODS: Twenty-eight living donor candidates underwent preoperative CTA and MRA. Two blinded radiologists evaluated the anatomic types of the hepatic artery (HA) and portal vein (PV), and the number of aberrant hepatic veins (HVs) on both CTA and MRA, independently. Four grades of confidence levels were used to indicate the clarity of depiction of the HA and PV. Surgical findings were used as a standard of reference. RESULTS: For determining the anatomic types of the HA and PV, and the number of aberrant HVs, CTA and MRA did not significantly differ in terms of accuracy ([89%, 96%, and 68% on CTA] vs. [86%, 93%, and 68% on MRA] for reader 1, P>0.05; and [93%, 100%, and 86% on CTA] vs. [89%, 93%, and 79% on MRA] for reader 2, P>0.05). Confidence for the depiction of major branches of HA and PV did not differ between CTA and MRA, except for a better depiction of the left HA (LHA) on CTA (P<0.05) CONCLUSION: In living donor candidates, both CTA and MRA can provide a complete evaluation of the hepatic vascular anatomy.

Adolescent↗

PubMed2006

Radiofrequency ablation of the porcine liver in vivo: increased coagulation with an internally cooled perfusion electrode.

RATIONALE AND OBJECTIVES: A major limitation of radiofrequency (RF) ablation is its inability to produce a large enough diameter of coagulation necrosis to encompass hepatic tumors with an appropriate ablative margin at a single RF application. We evaluated the in vivo efficiency of RF ablation (RFA) using an internally cooled perfusion (ICP) electrode with hypertonic saline infusion to induce coagulation necrosis compared with that of RFA using single needle electrode types. MATERIALS AND METHODS: RF was applied to a porcine liver in monopolar mode using a 200 W generator and an internally cooled electrode (group A) or an ICP electrode (group B) at 200 W for 12 minutes or using a 60 W generator with a perfusion electrode at 40 W for 20 minutes (group C). In total, 36 (3 x 12) ablation zones were created using the three different regimens. In group B, 14.6% NaCl solution was infused at 1 mL/minute and in group C, 0.9% NaCl solution was infused at 1.5 mL/minute. The three groups were compared in terms of amount of delivered RF energy and dimensions and the coefficients of variation of the ablation zones. RESULTS: The mean energies applied in the three groups were 52.3 +/- 10.3 kJ for group A, 115.4 +/- 10.5 kJ for group B, and 38.5 +/- 11.5 kJ for group C, respectively (P < .05). The mean ablation volumes in groups A, B and C were 13.1 +/- 4.7 cm3 in group A, 43.7 +/- 17.5 cm3 in group B, and 26.3 +/- 20.2 cm3 in group C, respectively (P < .05). In addition, the coefficients of variation of the volumes of the ablation zones in groups A, B, and C were 0.36, 0.4, and 0.78, respectively. CONCLUSIONS: RFA using the ICP electrode showed better performance in terms of creating a larger ablation zone than RFA using an internally cooled or a perfusion electrode.

Animals↗

PubMed2006

Superparamagnetic iron oxide-enhanced liver magnetic resonance imaging: comparison of 1.5 T and 3.0 T imaging for detection of focal malignant liver lesions.

OBJECTIVES: We sought to compare the image quality, lesion conspicuity, and the diagnostic performance of 1.5 T and 3.0 T superparamagnetic iron oxide-enhanced liver magnetic resonance imaging (MRI) for detecting focal malignant hepatic lesions. MATERIALS AND METHODS: A total of 35 patients with pathologically proven liver malignancy underwent both 1.5 and 3.0 T SPIO-enhanced MRI. The diagnostic accuracy was evaluated using the alternative-free response receiver operating characteristic method. Image artifacts, quality, and the lesion conspicuity were analyzed. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the lesion were calculated. RESULTS: No significant difference of area under ROC curve (Az value) was noted. The mean SNR and CNR of the lesions was higher in the 3.0 T sets. There was no difference between the 1.5 T and the 3.0 T image sets for lesion conspicuity, but the image quality was better on 1.5 T. Motion and susceptibility artifacts were more frequent on 3.0 T. CONCLUSION: Diagnostic accuracies of the SPIO-enhanced MRI were equivalent on the 1.5 T and 3.0 T image sets. More prominent artifacts on 3.0 T superparamagnetic iron oxide-enhanced liver MRI counteracted advantage of higher SNR and CNR of 3.0 T.

Contrast Media↗

PubMed2006

Radiofrequency renal ablation: in vivo comparison of internally cooled, multitined expandable and internally cooled perfusion electrodes.

PURPOSE: To evaluate the in vivo efficiency of radiofrequency ablation using an internally cooled-perfusion (ICP) electrode for inducing coagulation necrosis compared with those of RFA using internally cooled or multitined expandable electrodes in porcine kidneys. MATERIALS AND METHODS: Using a 200 W generator and internally cooled and ICP electrodes or a 150 W generator and a multitined expandable electrode, a total of 15 radiofrequency ablations were performed in the kidneys of nine pigs. After placement of an electrode in the lower pole of a kidney, one ablation zone was created using one of three different regimens: group A, radiofrequency ablation using an internally cooled electrode; group B, radiofrequency ablation using an ICP electrode with 14.6% NaCl solution instillation at 1 mL/minute; group C, radiofrequency ablation using a multitined expandable electrode. Three days after the procedures, contrast-enhanced CT scans were obtained to evaluate ablation region volumes, and kidneys were harvested for gross measurements. The three groups were compared with respect to technical parameters such as changes in impedance and current during radiofrequency ablation. The dimensions of thermal ablation zones created in the three groups were compared histologically. RESULTS: In vivo study showed that ICP electrode allowed a greater energy delivery than internally cooled or multitined expandable electrode during radiofrequency ablation: 63.3 +/- 8.8 kJ in group A; 101 +/- 3.3 kJ in group B; and 61.8 +/- 12.5 kJ (P < .05). In vivo studies showed radiofrequency ablation using ICP electrode achieved larger mean coagulation volumes than radiofrequency ablation using the other electrodes: 12.0 +/- 3.9 cm(3) in group A; 30.5 +/- 7.6 cm(3) in group B; and 11.6 +/- 6.7 cm(3) in group C (P < .05). In addition, group B had a larger mean short-axis diameter of radiofrequency-induced coagulation necrosis than groups A or C: 2.6 +/- 0.5 cm in group A; 3.6 +/- 0.4 cm in group B; and 2.4 +/- 0.7 cm in group C (difference between groups B and C: P < .05). CONCLUSIONS: Radiofrequency ablation using an ICP electrode showed better performance at creating coagulation necrosis than radiofrequency ablation using internally cooled or multitined expandable electrodes in this porcine renal model.

Analysis of Variance↗

PubMed2006

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.

Aged↗

PubMed2006

Macrocystic neoplasms of the pancreas: CT differentiation of serous oligocystic adenoma from mucinous cystadenoma and intraductal papillary mucinous tumor.

OBJECTIVE: The purpose of our study was to determine useful CT criteria for differentiating serous oligocystic adenomas of the pancreas from other similarly presenting neoplasms, such as mucinous cystadenoma and intraductal papillary mucinous tumor of the branch duct type. MATERIALS AND METHODS: Forty-one patients with histologically confirmed macrocystic neoplasms of the pancreas were enrolled: serous oligocystic adenoma in 10 patients, mucinous cystadenoma in 13, and intraductal papillary mucinous tumor in 18. Location, greatest dimension, shape, presence of mural nodules, presence of wall calcification, and the extent and degree of main pancreatic duct (MPD) dilatation were analyzed with CT. The lesions were categorized into seven groups according to their shapes: multicystic, lobulated contour with and without internal septation, smooth contour with and without internal septation, pleomorphic cystic, and clubbed fingerlike cystic. Comparative studies were performed using Fisher's exact test and the Mann-Whitney U test. RESULTS: Significant differences in lesion shape were found between serous oligocystic adenoma and the other macrocystic neoplasms (mucinous cystadenoma [p < 0.05], intraductal papillary mucinous tumor [p < 0.05]). Serous oligocystic adenoma had a multicystic or lobulated contour with or without septation, whereas mucinous cystadenoma had a smooth contour with or without septation and intraductal papillary mucinous tumor had either a pleomorphic or a clubbed fingerlike cystic shape. Serous oligocystic adenoma showed proximal MPD dilatation from the lesion, whereas intraductal papillary mucinous tumor showed distal or whole MPD dilatation (p < 0.05). No significant difference was apparent among the three diseases in terms of location, greatest dimension, or presence of calcification or mural nodules. CONCLUSION: Serous oligocystic adenoma of the pancreas has characteristic CT findings that differentiate it from other cystic tumors. It appears as a multicystic or lobulated cystic lesion with septation.

Adult↗