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Biomedical subjects

Joon Koo Han

Publications and source records attributed to Joon Koo Han.

At least 73 records · Page 4Linked to original sources
PubMed2004

Gastrointestinal stromal tumors of the duodenum: CT and barium study findings.

OBJECTIVE: The purpose of this study was to describe the CT and radiographic features of gastrointestinal stromal tumors of the duodenum. CONCLUSION: Gastrointestinal stromal tumors of the duodenum appear on barium studies as extrinsically compressing or submucosal masses with or without ulceration. These tumors usually appear on contrast-enhanced CT as well-defined masses with an exoenteric growth pattern and relatively good heterogeneous enhancement.

Adult↗
PubMed2004

Relationship between various patterns of transient increased hepatic attenuation on CT and portal vein thrombosis related to acute cholecystitis.

OBJECTIVE: We sought to investigate the prevalence of portal vein thrombosis in patients with acute cholecystitis and the relationship between portal vein thrombosis and the various patterns of transient increased hepatic attenuation on CT. MATERIALS AND METHODS: We studied 72 of 107 patients with acute cholecystitis who, during a 3-year period, underwent dual-phase contrast-enhanced CT before percutaneous cholecystostomy or cholecystectomy. CT scans were retrospectively reviewed for the presence of portal vein thrombosis and location of the thrombi and for patterns of transient increased hepatic attenuation, which were classified as either pericholecystic, segmental, or mixed. RESULTS: Portal vein thrombi (two in hepatic segment IV, three in the left portal vein, and one in the right posterior portal vein) were found in six (8.3%) of 72 patients, and in those patients, transient increased attenuation with a segmental (five patients) or mixed (one patient) pattern was seen on CT. The pattern of transient increased attenuation in the 54 patients without portal vein thrombosis was pericholecystic in 41 (75.9%) and mixed in 13 (24.1%). Nineteen patients had segmental distribution (segmental or mixed pattern) that in 31.6% (6/19) of the patients was associated with portal vein thrombosis. Segmental distribution was more frequently found in those patients who had acute cholecystitis with portal vein thrombosis than in those who had only acute cholecystitis (p = 0.001). CONCLUSION: In patients with acute cholecystitis, portal vein thrombosis is not uncommon. Patterns of transient increased hepatic attenuation were found to vary, depending on the presence or absence of portal vein thrombosis.

Acute Disease↗
PubMed2004

Gastrointestinal stromal tumors of the stomach: CT findings and prediction of malignancy.

OBJECTIVE: The purpose of this study was to identify predictors of malignancy on CT for the evaluation of gastrointestinal stromal tumors of the stomach. MATERIALS AND METHODS: The medical records at our institution of 81 patients with a histologic diagnosis of gastrointestinal stromal tumor of the stomach were reviewed. Two radiologists retrospectively reviewed the CT findings by consensus with respect to lesion size, contour, tumor growth pattern, enhancing pattern, degree of enhancement, mesenteric fat infiltration, ulceration, calcification, lymphadenopathy, direct invasion to adjacent organ, and distant metastasis. Categoric variables were compared using the chi-square or Fisher's exact test. Multiple stepwise logistic regression analysis by means of forward selection was performed to determine significant predictors of high mitotic rate. Univariate analysis and multivariate analysis were also performed in a subgroup of 36 tumors with maximal diameter of 5 cm or smaller. RESULTS: Size, presence of an ulcer, mesenteric fat infiltration, direct organ invasion, and metastasis were more frequently observed during univariate analysis in tumors with a high mitotic rate (p < 0.05). With stepwise logistic regression analysis, the size (odds ratio, 2.57; 95% CI; 1.42-4.67) was the only significant predictor of a high mitotic rate. In a subgroup of 36 tumors 5 cm or smaller, differentiation of benign from malignant tumors was not possible using CT. CONCLUSION: Although presence of an ulcer, mesenteric fat infiltration, direct organ invasion, and metastasis were more frequently observed in tumors with a high mitotic rate, no CT feature, other than size, was found to have predictive value with respect to malignant gastrointestinal stromal tumors of the stomach.

Adult↗
PubMed2004

Sonographic features of an intraductal polypoid mass: differentiation between hepatocellular carcinoma and intraductal cholangiocarcinoma.

OBJECTIVE: To identify laboratory and sonographic features capable of differentiating hepatocellular carcinoma (HCC) invading the bile duct from intraductal cholangiocarcinoma (IDCCC). METHODS: Nine patients with HCC invading the bile duct and 8 patients with IDCCC were found in our radiologic and pathologic database. Laboratory (alpha-fetoprotein, cancer antigen 19-9, total bilirubin, and alkaline phosphatase) and sonographic findings were retrospectively reviewed by 2 reviewers by consensus. Sonographic findings included the presence and echo texture of parenchymal masses, the margin and echo texture of intraductal masses, continuity between parenchymal and intraductal masses, cystic ductal dilatation or wall thickening of the bile duct, and the presence of associated chronic liver disease. RESULTS: Significant differences were found in the levels of total bilirubin (14 versus 3.5 mg/dL), alpha-fetoprotein (2984 versus 5 ng/mL), and cancer antigen 19-9 (8574 versus 1861 U/mL) in HCC and IDCCC (P <.05). Echogenicity of the intraductal masses was iso or low in 8 (88.9%) of 9 HCCs and 3 (37.5%) of 8 IDCCCs (P <.05). In all 7 patients with HCC but in no patient with IDCCC, the parenchymal masses were contiguous with the intraductal masses (P <.05). Cystic ductal dilatation of bile duct was seen in 8 (88.9%) of 9 HCCs and 3 (37.5%) of 8 IDCCCs (P <.05). All 9 (100%) of 9 HCCs and 3 (37.5%) of 8 IDCCCs were associated with chronic liver disease (P <.05). Parenchymal masses occurred in 7 patients with HCC (77.8%) and in 3 patients with IDCCC (37.5%), but the difference was not statistically significant (P =.153). The margins of the intraductal masses were smooth in all 9 (100%) of 9 HCCs and lobulated in 3 (37.5%) of 8 IDCCCs (P =.082). CONCLUSIONS: Combined interpretation of laboratory and sonographic features may help in the differentiation of HCC with bile duct invasion and IDCCC.

Adult↗
PubMed2003

Combined treatment of radiofrequency ablation and acetic acid injection: an in vivo feasibility study in rabbit liver.

The aim of this study was to compare the effects of percutaneous radiofrequency ablation (RFA) combined with percutaneous acetic acid injection (PAI) and either therapy alone for their effects on in vivo rabbit liver tissue. Thirty New Zealand white rabbits were included in this study and were allocated to three groups: group A, conventional RFA (n = 10); group B, PAI (n = 10); and group C, combined RFA and PAI (n = 10). Under US guidance, 1 ml of 50% acetic acid was injected into the target area of the liver parenchyma through a 21-G Chiba needle before performing RFA. The RFA was then performed using a 17-G internally cooled electrode with 1-cm active tip, and RF energy (30 W) was applied for 3 min with or without acetic acid injection. After RFA or PAI, contrast-enhanced CT and CT pathologic correlation were performed. The maximum diameters of the thermal lesions in each group were compared. All procedures were technically successful, and a total of 30 lesions (10 lesions for each group) were produced. The mean maximum diameter of the coagulation necrosis in the rabbits of group C (25+/-9 mm) was significantly larger than the diameters of the other groups: 12.2 +/- 1 mm (group A) and 14.3 +/- 3 mm (group B; p = 0.001). On contrast-enhanced CT scanning, the lesions of group B (7 of 10, 70%) appeared frequently irregular compared with those of groups A (2 of 10, 20%) and C (4 of 10, 40%; p = 0.08). There were seven complications (23.3%): a localized hematoma in a group-A rabbit; two hematomas and one chemical peritonitis in group-B rabbits; and a hematoma, a chemical peritonitis, and a burn injury to the stomach in group-C rabbits. Compared with the group-A rabbits (1 of 10, 10%), the group-B (3 of 10, 30%) and group-C rabbits (3 of 10, 30%) showed a tendency toward complications, but the difference was not significant (p = 0.48). Under the present experimental condition, combined RFA and PAI was able to increase the diameter of coagulation necrosis up to 2.5 cm without significantly increasing complications.

Acetic Acid↗
PubMed2003

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

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

Abscess↗
PubMed2003

Dynamic contrast-enhanced MR imaging of VX2 carcinomas after X-irradiation in rabbits: comparison of gadopentetate dimeglumine and a macromolecular contrast agent.

RATIONALE AND OBJECTIVES: To compare enhancement patterns of gadomer-17 with those of gadopentetate dimeglumine in VX2 carcinomas after irradiation on rabbits. METHODS: Twelve rabbits with VX2 carcinoma in the thigh underwent dynamic contrast-enhanced magnetic resonance (MR) imaging with gadopentetate dimeglumine and gadomer-17 at 24-hour intervals before (n = 12), 3 days (group 1, n = 12), 1 month (group 2, n = 8) and 2 months (group 3, n = 4) after 30 Gy irradiation. After taking postirradiation MR images, 4 rabbits were killed for histopathologic examination at each time interval. The enhancement characteristics in MR imaging and morphology of tumor vessels in histopathologic specimen were assessed. RESULTS: After gadopentetate dimeglumine injection, the enhancement characteristics were not different among tumors before and after irradiation (P > 0.05). For gadomer-17, the enhancement ratios decreased after irradiation. The shape of the curves for tumor enhancement before irradiation was significantly different from curves of group 1(P < 0.05). The specimens from group 3 showed sclerosis and wall thickening in arterioles. CONCLUSIONS: Dynamic contrast-enhanced MR imaging with a gadomer-17 reveals increased capillary permeability at an early phase after irradiation and chronic obliterating vasculopathy at delayed phase.

Animals↗
PubMed2003

Recurrent bronchobiliary fistula: unsuccessful management with repeated insertion of metallic biliary stent.

This case of a recurrent bronchobiliary fistula was first managed temporarily with repeated metallic biliary stent placement, and finally required surgery. A 65-year-old man, who had undergone a hepatic resection for metastatic colon carcinoma, with a bronchobiliary fistula was treated with metallic biliary stent placement for a stenosis in the common bile duct. During 16 months of follow-up, the biliptysis recurred twice by a recurrent stricture of the common bile duct, which was managed by placement of a second and third stent in a coaxial manner. Three months after placement of the third stent, jaundice developed and the patient finally underwent a Roux-en-Y choledochojejunostomy.

Aged↗
PubMed2003

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

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

Animals↗
PubMed2003

Value of four-dimensional ultrasonography in ultrasonographically guided biopsy of hepatic masses.

OBJECTIVE: To assess the value of four-dimensional ultrasonography (dynamic three-dimensional ultrasonography with the added dimension of time) in ultrasonographically guided biopsy procedures of focal hepatic masses. METHODS: Four-dimensional ultrasonographically guided biopsy experiments using a freehand technique were performed in phantoms that simulated human liver tissue and had target material. After the protocol was determined and Institutional Review Board approval was obtained, 12 patients underwent four-dimensional ultrasonographically guided biopsy of focal hepatic masses by informed consent. Planar images using 3 orthogonal planes plus a volume-rendered image were used for real-time guidance during the biopsy procedure. RESULTS: Four-dimensional ultrasonography improved visualization of biopsy devices in all 12 patients (100%) regardless of minor changes in transducer position during the biopsy procedures. Four-dimensional ultrasonography allowed more intuitive apprehension of the spatial relationship of the needle and the target lesion and thus helped in adjusting the needle to an optimal prefiring position in 8 patients (67%). With regard to procedure time, four-dimensional ultrasonographically guided biopsy was comparable with standard two-dimensional ultrasonographically guided techniques. CONCLUSIONS: Compared with standard two-dimensional ultrasonographically guided biopsy, four-dimensional ultrasonography provides improved visualization of biopsy devices and more perceptible information on the spatial relationship between the biopsy needle and the target lesion.

Biopsy, Needle↗
PubMed2003

Extended field-of-view sonography: advantages in abdominal applications.

OBJECTIVE: To show the advantages of extended field-of-view sonography in abdominal applications. METHODS: Thirty-one cases were prospectively analyzed in our study. Extended field-of-view images were obtained when the radiologist decided that they would offer potential advantages for the examination. When extended field-of-view scanning was used, the radiologist determined prospectively whether it was useful according to several categories. Images were obtained with a 2- to 5-MHz curved array transducer or 4- to 9- and 5- to 12-MHz linear array transducers. RESULTS: Extended field-of-view sonography provided several potential benefits over conventional sonography in the abdominal area. The advantages of extended field-of-view sonography were better demonstration of the spatial relationship between lesions and adjacent normal structures in 18 cases (58%), accurate quantification of sizes or volumes of large organs or lesions in 16 (52%), better display of the extended and tubular structures in 6 (19%), usefulness for clinical consultations in 7 (23%), and documentation comparable with that of computed tomography or magnetic resonance imaging in 10 (32%). CONCLUSIONS: Extended field-of-view sonography provided the anatomic context of the lesion in its surroundings and allowed precise measurement and tracing of the extended and tubular structures. The method has notable advantages and clinical applications.

Abdomen↗
PubMed2003

Hepatocellular carcinoma: assessment of vascularity with single-level dynamic ultrasonography during the arterial phase.

OBJECTIVE: To evaluate the hemodynamic features of hepatocellular carcinoma on single-level dynamic ultrasonography during the arterial phase. METHODS: Twenty-two hepatocellular carcinomas were examined by single-level dynamic ultrasonography with high transmit intensity and SH U 508A. The scans were performed for 40 seconds with a 1-second interval between each ultrasound transmission and with individual optimization of the scan delay time. The times of initiation of enhancement for both the hepatic artery and the tumor and the time of maximal enhancement for the tumor were recorded, and the mean echo values at every second for the tumor and hepatic parenchyma were measured. RESULTS: Twelve tumors showed hyperechoic enhancement compared with hepatic parenchyma throughout the scans. The other 10 showed hyperechoic enhancement during some segments (range, 8-34 seconds) and either isoechoic (n = 5) or hypoechoic (n = 5) enhancement during the remaining parts; the hyperechoic segments were often short (< 20 seconds, 14%). Although the times for initiation of enhancement for the hepatic artery and hepatocellular carcinoma and the time of maximal enhancement for the tumor varied, the tumor usually initiated enhancement immediately after the hepatic artery (r = 0.986; P = .000001). The interval between the time of initiation of enhancement for the tumor or hepatic artery and that of maximal enhancement for the tumor was significantly correlated with the tumor size (r = 0.700; P = .008; and r = 0.780; P = .002). CONCLUSIONS: With individual optimization of the scan delay time, single-level dynamic ultrasonography is useful for depicting the hypervascularity of hepatocellular carcinoma during the arterial phase.

Adult↗