Biomedical subjects

Young Taik Oh

Publications and source records attributed to Young Taik Oh.

15 recordsLinked to original sources

PubMed2006

Detection of hepatic metastasis: manganese- and ferucarbotran-enhanced MR imaging.

PURPOSE: To compare the mangafodipir trisodium (MnDPDP)-enhanced and ferucarbotran-enhanced magnetic resonance imaging (MRI) for the detection of hepatic metastases. MATERIAL AND METHODS: Twenty patients with known hepatic metastasis underwent MR imaging using mangafodipir trisodium and ferucarbotran in at least 1-day intervals. Thirty-eight metastases were confirmed either histologically or clinically. Two radiologists independently reviewed the MnDPDP-enhanced and ferucarbotran-enhanced sets in a random order. The sensitivity and accuracy of lesion detection and the ability to distinguish a benign lesion from a malignant lesion were compared by the areas (Az) under the receiver operating characteristic (ROC) curve. The lesion-liver contrast-to-noise ratios (CNR) were compared by paired t-test. RESULTS: The overall accuracy for detecting metastases was not significantly different between the MnDPDP set (Az=0.912 and 0.913 for reader 1 and 2, respectively) and the SPIO set (Az=0.920 and 0.950). The CNR at the MnDPDP-enhanced images and the SPIO-enhanced images were not significantly different (P=0.146). CONCLUSION: Both MnDPDP- and ferucarbotran-enhanced MRI have a comparable accuracy in detecting hepatic metastasis.

Adult↗

PubMed2006

Imaging findings of biliary and nonbiliary complications following laparoscopic surgery.

Laparoscopic techniques are evolving for a wide range of surgical procedures although they were initially confined to cholecystectomy and exploratory laparoscopy. Recently, surgical procedures performed with a laparoscope include splenectomy, adrenalectomy, gastrectomy, and myomectomy. In this article, we review the spectrum of complications and illustrate imaging features of biliary and nonbiliary complications after various laparoscopic surgeries. Biliary complications following laparoscopic cholecystectomy include bile ductal obstruction, bile leak with bile duct injury, dropped stones in the peritoneal cavity, retained CBD stone, and port-site metastasis. Nonbiliary complications are anastomotic leakage after partial gastrectomy, gangrenous cholecystitis after gastrectomy, hematoma at the anastomotic site following gastrectomy, gastric infarction after gastrectomy, port-site metastasis after gastrectomy, hematoma after splenectomy, renal infarction after adrenalectomy, and active bleeding after myomectomy of the uterus.

Biliary Tract Diseases↗

PubMed2006

Variation of the time to aortic enhancement of fixed-duration versus fixed-rate injection protocols.

OBJECTIVE: The objective of the study was to clarify whether a fixed-duration injection protocol is useful in determining the optimal scan delay time without the need for a bolus-tracking technique. MATERIALS AND METHODS: Three hundred eighteen patients underwent a helical CT examination using a bolus-tracking technique. All the examinations were performed after administering a nonionic contrast medium (300 or 370 mg I/mL; 2 mL/kg of body weight for patients weighing < or = 75 kg, 150 mL for those weighing > 75 kg). The patients were assigned to one of three groups according to the injection protocol. The injection rate was alternated to 3 or 4 mL/sec in group 1. The injection duration was 38 or 47 sec in groups 2 and 3, respectively. The aortic arrival time and the 100-H threshold time in each patient were measured. The mean values and the variations in the aortic arrival time and 100-H threshold time according to the injection protocols and the contrast media were compared. RESULTS: The mean variations (+/- SD) of aortic arrival times and 100-H thresholds in group 2 (aortic arrival time = 16.1 +/- 2.7 sec, 100-H threshold time = 19.6 +/- 2.9 sec) were smaller than in groups 1 (16.3 +/- 3.0 sec and 19.9 +/- 3.7 sec, respectively) and 3 (16.8 +/- 3.5 sec and 20.4 +/- 4.1 sec, respectively). However, the range of aortic arrival times and 100-H threshold times was more than 10 sec for all groups. The mean aortic arrival time and 100-H threshold time for all patients were 16.5 and 20.0 sec, respectively, and did not vary significantly with the injection protocol and concentration of contrast medium. CONCLUSION: The individual variations of the aortic arrival and 100-H threshold times can be reduced using a fixed-duration injection technique, but there are still substantial variations. Therefore, a bolus-tracking technique is recommended for optimal timing of arterial phase scanning.

Adult↗

PubMed2006

Optimal scan window for detection of hypervascular hepatocellular carcinomas during MDCT examination.

OBJECTIVE: The purpose of this study was to define the optimal scan window for acquiring arterial phase images in the detection of hypervascular hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: Biphasic arterial phase CT examinations were performed using a 16-MDCT scanner on 198 patients (159 men and 39 women; mean age, 59 years; age range, 25-82 years) with nodular HCC. All examinations were performed after administering 120-150 mL of a nonionic contrast media (370 mg I/mL) at a rate of 3-4 mL/s. The scan delay--the interval between when the bolus-tracking program detected the threshold enhancement of 100 H in the abdominal aorta and the start of the first arterial scan-was progressively lengthened by 2-second intervals, from 10 seconds in group 1 to 20 seconds in group 6. The second arterial phase scan was started 6 seconds after the end of the early scan. A tube collimation of 1.5 mm, a table feed of 18 mm per rotation, an image thickness of 3 mm, and 3-mm increments were used. The duration of each phase scan was 4.5-8.8 seconds. Tumor-to-liver attenuation difference (TLAD) at the first (TLAD1) and second (TLAD2) arterial phase images were compared lesion by lesion. Four observers assigned subjective ratings of visual conspicuity and individual preferences for each phase in each group. RESULTS: The mean threshold time (100 H) was 18.4 +/- 3.1 seconds, and 97% of patients were within the range of 13-24 seconds. The mean TLAD1 of groups 3 to 6 and the mean TLAD2 of groups 1 to 5 were all comparable; they were also all significantly (p < 0.005) higher than the mean TLAD1 of groups 1 and 2 and the mean TLAD2 of group 6. In groups 1 and 2, the mean TLAD2 was significantly higher than the mean TLAD1 (p < 0.001); in groups 5 and 6, the mean TLAD1 was significantly higher than the mean TLAD2 (p < 0.001). In groups 3 and 4, the mean TLAD1 and TLAD2 were similar. The visual conspicuity and individual preferences were higher for the first-phase image in groups 3 to 6 and the second-phase image in groups 1 and 2. CONCLUSION: The optimal scan window for arterial phase images in the detection of HCC seems to be approximately 14-30 seconds from the 100-H threshold.

Adult↗

PubMed2006

Solid pseudopapillary tumor of the pancreas: typical and atypical manifestations.

OBJECTIVE: The purpose of this pictorial essay is to illustrate the various appearances of solid pseudopapillary tumor of the pancreas. CONCLUSION: Solid pseudopapillary tumor of the pancreas is a rare neoplasm usually found in young women. Typical solid pseudopapillary tumor is characterized by a well-encapsulated mass with varying amounts of intratumoral hemorrhage. However, the tumor can have an atypical appearance, such as metastasis, ductal obstruction, parenchymal and extracapsular invasion, simulation of islet cell tumor, intratumoral calcification, and occurrence in a male patient. The typical and atypical manifestations of solid pseudopapillary tumor can be visualized with cross-sectional imaging.

Adult↗

PubMed2005

Juvenile prostatic hyperplasia.

Benign prostatic hyperplasia is common in aging men, but rare in childhood. We report a case of juvenile prostatic hyperplasia in a 10-year-old boy, who visited our clinic for hematuria and voiding symptoms. Radiologic studies revealed a huge prostate protruding into the bladder. The prostate was 33 g. The prostate biopsy showed no evidence of cancer. At 13 years of age, he was seen again because of general weakness, fever, and voiding difficulty. Bilateral hydroureteronephrosis was found on radiologic studies, and his serum creatinine was elevated. The prostate was 55 g. Suprapubic prostatectomy was performed.

Age Factors↗

PubMed2005

Preoperative MRI of potential living-donor-related liver transplantation using a single dose of gadobenate dimeglumine.

OBJECTIVE: This article evaluates the feasibility of single-dose gadobenate dimeglumine-enhanced MRI as both an angiographic and biliary contrast medium for making a preoperative evaluation of the donor candidates for a living-donor-related liver transplantation. SUBJECTS AND METHODS: Eleven right hepatic lobe donors underwent MRI examinations using T1- and T2-weighted imaging and T2-weighted MR cholangiography (MRC). The MR angiography (MRA) and contrast-enhanced (CE) T1-weighted MRC images then were obtained after injecting a single dose of gadobenate dimeglumine. One radiologist and one surgeon prospectively reviewed all the MRI examinations for hepatic vascular and biliary abnormalities and compared them with the surgical findings and intraoperative cholangiograms. In addition, two blinded reviewers evaluated the two sets of MRC (T2-weighted MRC set and T2-weighted MRC plus CE-T1-weighted MRC set) retrospectively and recorded the anatomic types of the hilar biliary branching pattern along with their confidence in the interpretation. RESULTS: Prospective analysis detected the following vascular variants: hepatic arterial variation in two patients, portal venous variation in one, and a significantly large accessory hepatic vein (> 5 mm) in one. Biliary variants also were identified in two patients. All the MRI findings on the vascular and biliary anatomy were corroborated intraoperatively. Retrospective analysis showed that the mean diagnostic confidence in the combined set was significantly higher than that of the T2-weighted MRC alone by both reviewers (p < 0.05). CONCLUSION: Obtaining both MRA and CE-T1-weighted MRC is feasible using a single dose of gadobenate dimeglumine. Therefore, gadobenate dimeglumine-enhanced MRI might play a role as a preoperative imaging technique for the vascular and biliary evaluation of potential living donors.

Adolescent↗

PubMed2004

Detection and characterization of focal hepatic lesions: mangafodipir vs. superparamagnetic iron oxide-enhanced magnetic resonance imaging.

PURPOSE: To compare the mangafodipir-enhanced magnetic resonance (MR) and superparamagnetic iron oxide (SPIO)-enhanced images for their ability to detect and characterize focal hepatic lesions. MATERIALS AND METHODS: Unenhanced, mangafodipir-enhanced, and SPIO-enhanced hepatic MR images obtained from 64 patients were analyzed. A total of 121 hepatic lesions were included: 66 hepatocellular carcinomas (HCCs), 26 metastases, 14 hemangiomas, 5 cysts, 3 cholangiocarcinomas, 4 focal nodular hyperplasias (FNHs), 2 abscesses, and 1 adenoma. Two radiologists independently reviewed the two sets of images in a random order: 1) the unenhanced and mangafodipir-enhanced images (the mangafodipir set) and 2) the unenhanced and SPIO-enhanced images (the SPIO set). This study compared the accuracy of lesion detection, the ability to distinguish between a benign and malignant lesion, and the ability to distinguish between the hepatocellular and nonhepatocellular origins of the lesions using the areas (Az) under the receiver operating characteristic (ROC) curve. RESULTS: The overall accuracy for detecting focal lesions was significantly higher (P < 0.05) with the SPIO set (Az = 0.846 and 0.871 for readers 1 and 2, respectively) than with the mangafodipir set (Az = 0.716 and 0.766). Most of the lesions detected only with the SPIO-enhanced MR images by the readers were small HCCs. For lesions larger than 15 mm, the sensitivities of the two contrast enhancement techniques were similar for both readers. The accuracy of the mangafodipir and SPIO sets in distinguishing between benign and malignant lesions was comparable. The accuracy for distinguishing between the hepatocellular and nonhepatocellular origins of the lesions was significantly higher (P < 0.05) using the mangafodipir set (Az = 0.897 and 0.946) than using the SPIO set (Az = 0.741 and 0.833). CONCLUSION: SPIO- and mangafodipir-enhanced images were comparable for detection of focal hepatic lesions other than small HCCs, which were better detected on the SPIO-enhanced images. Mangafodipir-enhanced images are likely better than the SPIO-enhanced images for distinguishing between focal liver lesions with a hepatocellular or nonhepatocellular origin.

Adult↗

PubMed2004

Preoperative MRI of rectal cancer with and without rectal water filling: an intraindividual comparison.

OBJECTIVE: The purpose of our study was to determine if a rectal distention using warm water may improve the accuracy of MRI for the preoperative staging of rectal carcinoma. SUBJECTS AND METHODS. Sixty-two patients with surgically proven rectal carcinomas underwent pelvic MRI before and after a rectal distention by warm water. Four radiologists, who were blinded to the study, reviewed each set of T1- and T2-weighted axial images obtained before and after the rectal distention and scored the image of the tumor. The accuracies for determining the tumor penetration of the outer wall of the rectum and the regional lymph node involvement were compared by analyzing the area under the receiver operating characteristic curve (A(z)). RESULTS: For all reviewers, the tumor depiction scores were significantly higher in the distended images (3.8-3.9 for reviewers 1-4) than in the nondistended images (3.0-3.2) (p < 0.01). For determining the outer wall penetration, the accuracy of the three reviewers was significantly higher with the rectal distention images than with the nondistended images (p < 0.05). The mean accuracy of the all reviewers was significantly better with the distended images (A(z) = 0.922) than with the nondistended images (A(z) = 0.841) (p < 0.05). For determining the presence of regional lymph node involvement, all the reviewers came to similar conclusions in analyzing the two image sets. CONCLUSION: Rectal distention by water filling may improve the depiction of a primary rectal tumor and the assessment accuracy of a perirectal tumor extension, but it does not improve the accuracy for determining the presence of regional lymph node involvement.

Adult↗

PubMed2003

Focal hepatic lesions: detection and characterization with combination gadolinium- and superparamagnetic iron oxide-enhanced MR imaging.

PURPOSE: To compare gadolinium- and superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging for detection and characterization of focal hepatic lesions when different contrast agent administration sequences are used. MATERIALS AND METHODS: Unenhanced, dynamic gadolinium-enhanced, and SPIO-enhanced hepatic MR images were obtained in 134 patients. SPIO-enhanced MR imaging was performed immediately after gadolinium-enhanced dynamic MR imaging in 50 patients, 1 day after gadolinium-enhanced dynamic MR imaging in 40 patients, and before gadolinium-enhanced dynamic MR imaging in 44 patients. Two radiologists independently reviewed the gadolinium image set (unenhanced and gadolinium-enhanced dynamic MR images) and the SPIO image set (unenhanced and SPIO-enhanced MR images) in random order. Lesion detection sensitivity and lesion characterization accuracy were compared by analyzing the area under the receiver operating characteristic curve (Az). RESULTS: Overall lesion detection accuracy for pooled data was significantly higher with the SPIO set (Az = 0.903) than with the gadolinium set (Az = 0.857) (P <.05). When hypovascular lesions were excluded, the detection rate was similar with the two sets. When hepatocellular carcinomas were excluded, the detection rate was significantly higher with the SPIO set (P <.01). Readers were more accurate in differentiating benign from malignant lesions with the gadolinium set (Az = 0.915) than with the SPIO set (Az = 0.847) (P <.01). Detection accuracy tended to be better with the images obtained after the second contrast agent was used. CONCLUSION: Hypovascular lesion detection was better with SPIO-enhanced MR images than with gadolinium-enhanced MR images. Detection and characterization of hypervascular lesions were improved with gadolinium-enhanced MR images.

Adult↗

PubMedDate not supplied

Annular pancreas: emphasis on magnetic resonance cholangiopancreatography findings.

An annular pancreas is a rare congenital anomaly in which a portion of the pancreatic tissue surrounds the duodenum. Magnetic resonance cholangiopancreatography (MRCP) is used extensively for evaluating the pancreatobiliary ducts. There have been only few cases in which MRCP clearly demonstrated the types of annular ducts, however. Two cases of an annular pancreas based on a new classification of the morphologic type are reported.

Adult↗

PubMedDate not supplied

Optimal delay time for the hepatic parenchymal enhancement at the multidetector CT examination.

The objective of this study was to determine the optimal scan delay time after hepatic parenchymal enhancement using a 16-channel multidetector row helical CT (MDCT) scanner. Two hundred fifty-five consecutive patients underwent biphasic CT scans using a 16-channel MDCT. In group A (n = 125), two hepatic venous phase scans (HVP1 and HVP2) were obtained at 40 and 60 seconds, after 100-HU threshold time (T100HU) in the abdominal aorta. In group B (n = 130), HVP1 and HVP2 scans were obtained 50 and 70 seconds after T100HU. Both groups were divided into subgroups that were given different contrast media. Groups A1 and B1 received a contrast medium of 300 mgI/mL; groups A2 and B2 received a contrast medium of 370 mgI/mL. Each patient was injected with contrast medium at a dose of 2 mL/kg at a rate adjusted to the patient's body weight with a constant injection duration of 47 seconds. The attenuation values (HU) for the liver, portal vein, hepatic vein, and aorta were measured. The average HU was compared between the groups. Hepatic enhancement in the images obtained at 50 and 60 seconds after T100HU was greater (P < 0.05) than in images obtained at 40 and 70 seconds. These results were obtained with both contrast media. A few patients showed greater enhancement at a 40 seconds or 70 seconds. Hepatic enhancement was significantly greater in all scans using a contrast medium dose of 370 mgI/mL compared with the 300-mgI/mL dose (P < 0.05). Independent of the concentration of contrast medium, scan delays of 50 to 60 seconds after T100HU may provide optimal hepatic enhancement.

Adolescent↗

PubMedDate not supplied

Follow-up result afters negative findings on unenhanced hepatic MR imaging for hepatic metastasis from rectal cancer.

OBJECTIVE: To assess the follow-up results after negative findings on unenhanced hepatic MR imaging in rectal cancer patients who have undergone locally curative surgery. MATERIALS AND METHODS: From all pertinent imaging reports and medical records, we selected 255 patients who had negative results on unenhanced hepatic MR imaging. When selecting patients who had undergone curative resection, the following patients were excluded from the study: 1) patients in whom extrahepatic metastases were detected on preoperative staging work-ups, 2) patients in whom the surgery was judged to be non-curative due to peritoneal seeding or local aggressiveness. Cases with follow-up periods of less than 18 months were also excluded, as these cases were considered insufficient to confirm the negative outcomes. Thus, a total of 149 patients were ultimately enrolled in our study. The follow-up results of unenhanced MR imagings were assessed according to the assumption that the newly developed hepatic metastases had been false-negative lesions on preoperative MR image. RESULTS: During a median follow-up period of 29.3 months, 25 hepatic metastases were detected in 13 patients (8.7%), which indicated a negative predictive value of 91.3%. CONCLUSION: Unenhanced hepatic MR imaging provides a high negative predictive value with regard to the detection of hepatic metastasis in the preoperative evaluation of rectal cancer.

Adenocarcinoma↗

PubMedDate not supplied

Assessment of the prognostic factors for a local recurrence of rectal cancer: the utility of preoperative MR imaging.

OBJECTIVE: To determine the utility of MR imaging in evaluating the prognostic factors for a local recurrence of rectal cancer following a curative resection. MATERIALS AND METHODS: The preoperative MR images obtained from 17 patients with a local recurrence and 54 patients without a local recurrence, who had undergone a curative resection, were independently evaluated by three radiologists. The following findings were analyzed: the direct invasion of the perirectal fat by the primary rectal carcinoma, involvement of the perirectal lymph nodes, perirectal spiculate nodules, perivascular encasement, and an enlargement of the pelvic wall lymph nodes. The clinical and surgical profiles were obtained from the patients' medical records. The association of a local recurrence with the MR findings and the clinicosurgical variables was statistically evaluated. RESULTS: Of the MR findings, the presence of perivascular encasement (p = 0.001) and perirectal spiculate nodules (p = 0.001) were found to be significant prognostic factors for a local recurrence. Of the clinicosurgical profiles, the presence of a microscopic vascular invasion (p = 0.005) and the involvement of the regional lymph nodes (p = 0.006) were associated with a local recurrence. Logistic regression analysis showed that the presence of perirectal spiculate nodules was an independent predictor of a local recurrence (odds ratio, 7.382; 95% confidence interval, 1.438, 37.889; p = 0.017). CONCLUSION: The presence of perirectal spiculate nodules and perivascular encasement on the preoperative MR images are significant predictors of a local recurrence after curative surgery for a rectal carcinoma. This suggests that preoperative MR imaging can provide useful information to help in the planning of preoperative adjuvant therapy.

Adult↗

PubMedDate not supplied

Comparison of CT and 18F-FDG pet for detecting peritoneal metastasis on the preoperative evaluation for gastric carcinoma.

OBJECTIVE: The aim of our study was to compare the accuracy of CT and (18)FFDG PET for detecting peritoneal metastasis in patients with gastric carcinoma. MATERIALS AND METHODS: One-hundred-twelve patients who underwent a histologic confirmative exam or treatment (laparotomy, n = 107; diagnostic laparoscopy, n = 4; peritoneal washing cytology, n = 1) were retrospectively enrolled. All the patients underwent CT and (18)F-FDG PET scanning for their preoperative evaluation. The sensitivities, specificities and accuracies of CT and (18)FFDG PET imaging for the detection of peritoneal metastasis were calculated and then compared using Fisher's exact probability test (p < 0.05), on the basis of the original preoperative reports. In addition, two board-certified radiologists and two board-certified nuclear medicine physicians independently reviewed the CT and PET scans, respectively. A receiver-operating characteristic curve analysis was performed to compare the diagnostic performance of CT and (18)F-FDG PET imaging for detecting peritoneal metastasis. RESULTS: Based on the original preoperative reports, CT and (18)F-FDG PET showed sensitivities of 76.5% and 35.3% (p = 0.037), specificities of 91.6% and 98.9% (p = 0.035), respectively, and equal accuracies of 89.3% (p = 1.0). The receptor operating characteristics curve analysis showed a significantly higher diagnostic performance for CT (Az = 0.878) than for PET (Az = 0.686) (p = 0.004). The interobserver agreement for detecting peritoneal metastasis was good (kappa value = 0.684) for CT and moderate (kappa value = 0.460) for PET. CONCLUSION: For the detection of peritoneal metastasis, CT was more sensitive and showed a higher diagnostic performance than PET, although CT had a relatively lower specificity than did PET.

Adolescent↗