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Biomedical subjects

T K Kim

Publications and source records attributed to T K Kim.

At least 109 records · Page 6Linked to original sources
PubMed1979

Chemical and electron microscopic studies of factors associated with the release of penicillinase from Staphylococcus aureus.

The effect of various factors such as sodium chloride, sodium citrate, pH, linase by Staphylococcus aureus ATCC 14458 was investigated. Penicillinase was measured at selected time intervals from supernates of cultures grown in Antibiotic Medium 3 broth containing various concentrations of salts or buffers or from supernates of cultures treated with lysostaphin and subsequently disrupted by French press treatment. Incubation of cells with media containing either sodium chloride (5, 10, and 15%), sodium citrate (5 and 10%), or organic buffers (Tris-HCl, 2.5, 5.0, and 7.5%; BES, 10 and 20%) resulted in a significant stimulation of the release of penicillinase when compared to control cells. It was also observed that pH 7.0-7.5 was optimal for penicillinase activity and release. From studies of enzymatic and mechanical disruption of cells, it was observed that an increase in ionic strength of the suspending medium to certain optimal levels appeared to stimulate the conversion of penicillinase to an extracellular form. Electron microscopic studies revealed that a large number of mesosomal vesicles seemed to be present in cells incubated for 4 hours in media containing various concentrations of sodium chloride. It is proposed that either appearance of vesicles or convolution of cell membrane, which may be caused by further synthesis of new membrane, is involved in stimulation of the synthesis and release of membrane-bound penicillinase.

Alkanesulfonates↗
PubMedDate not supplied

MRI of clonorchiasis and cholangiocarcinoma.

Intrahepatic cholangiocarcinomas are usually categorized as peripheral cholangiocarcinoma or hilar cholangiocarcinoma on the basis of the site of origin. Clonorchiasis is a trematodiasis caused by chronic infestation of liver flukes, which are largely confined to the Orient, from Japan to Vietnam. The close relationship between clonorchiasis and cholangiocarcinoma has long been emphasized. This paper discusses the efficacy and possible roles of MRI for imaging clonorchiasis and cholangiocarcinoma of the liver. Although sonography, CT, and direct cholangiography have been used traditionally to diagnose these diseases, the role of MRI has been increasing rapidly with dramatic progress of the MRI techniques. We review MRI findings of clonorchiasis and cholangiocarcinoma and discuss the potential usefulness of MRI.

Bile Duct Diseases↗
PubMedDate not supplied

T2-weighted breath-hold MRI of the liver at 1.0 T: comparison of turbo spin-echo and HASTE sequences with and without fat suppression.

To compare the clinical usefulness of T2-weighted breath-hold sequences for imaging the liver, 33 patients with 97 focal hepatic lesions were studied with a 1.0-T scanner by using T2-weighted breath-hold turbo spin-echo (SE) sequences and T2-weighted breath-hold half-Fourier single-shot turbo SE (HASTE) sequences with and without fat suppression. Images were quantitatively analyzed for liver signal-to-noise ratio (SNR) and lesion-to-liver contrast-to-noise ratios (CNR). Qualitative analysis was performed for lesion conspicuity, motion artifacts, and anatomic sharpness of extrahepatic structures. Breath-hold turbo SE imaging with fat suppression showed the highest CNR for cystic lesions and the best lesion conspicuity for cystic and solid lesions among the four sequences. For solid lesions, there was no significant difference of lesion-to-liver CNR between them. HASTE sequence was superior to turbo SE sequences in terms of motion artifacts; however, the usefulness for evaluating focal hepatic lesions was limited compared with turbo SE sequence with fat suppression. Addition of fat suppression was not helpful for HASTE imaging because of decreased lesion conspicuity and extrahepatic details without the advantage of reducing motion artifacts. This study suggests that turbo SE sequence with fat suppression is most useful for breath-hold T2-weighted liver imaging at 1.0 T. Addition of imaging without fat suppression can be considered for evaluating extrahepatic structures. HASTE sequence may have a role for imaging uncooperative patients due to absence of motion artifacts.

Abscess↗
PubMedDate not supplied

Anomalous origin of the right pulmonary artery from the ascending aorta: diagnosis by magnetic resonance imaging.

Anomalous origin of the right pulmonary artery from the ascending aorta is a rare congenital anomaly. Magnetic resonance imaging (MRI) was performed on three patients with anomalous origin of the right pulmonary artery from the ascending aorta. ECG-gated, T1-weighted, spin-echo MRIs and cine MRIs were obtained. In one patient, postoperative MRI was also obtained. Echocardiography and cardiac catheterization were performed in three patients and angiocardiography was performed in two. MRI clearly showed anomalous origin of the right pulmonary artery from the posterior aspect of the ascending aorta, as well as combined anomalies including patent ductus arteriosus, aortopulmonary window, and interruption of the aortic arch in all three patients. Echocardiography missed this anomaly in all three. We suggest that MRI is an accurate imaging modality in diagnosing anomalous origin of the right pulmonary artery from the ascending aorta, obviating the need to perform angiocardiography.

Adult↗
PubMedDate not supplied

Intragastric metastasis in a patient with gastric cancer: unusual CT manifestation.

We describe computed tomographic findings of intragastric metastasis in a patient with gastric cancer. On computed tomography, the intragastric metastatic lesion appeared as an exophytically growing cystic masss with minimal thickening of the adjacent gastric wall, thus mimicking an exophytically growing submucosal tumor or adenocarcinoma.

Adenocarcinoma↗
PubMedDate not supplied

Biliary obstruction in metastatic disease: thin-section helical CT findings.

BACKGROUND: We describe the thin-section helical computed tomographic (CT) findings of biliary obstruction caused by metastasis. METHODS: Thin-section helical CT (5 mm slice thickness, 1:1 pitch, portal phase) and direct cholangiography in 50 consecutive patients with biliary obstruction caused by metastases were reviewed retrospectively by three radiologists. The primary sites were the stomach ( n = 36), colon ( n = 12), jejunum ( n = 1), and uterus ( n = 1). The level of biliary obstruction was analyzed with the Bismuth classification, and the CT findings of biliary obstruction were classified into six types: small (<2 cm) periductal masses, large (>/=2 cm) periductal masses, extrinsic compression by a metastatic liver mass, high-attenuation intraductal mass, intrapancreatic mass, and no demonstrable lesion. RESULTS: The level of biliary obstruction was the hilum in 18 patients (36%), the proximal common duct in 20 (40%), the distal common duct in five (10%), and the periampullary area in seven (14%). Of 18 hilar obstructions, tumor involvement of the secondary confluence of intrahepatic bile ducts was seen in 10 (right in six, left in one, and bilateral in three). Periductal masses were seen in 68% (small in 18, large in 16). In one patient (2%), a large metastatic mass of the liver resulted in extrinsic compression and biliary obstruction. Lesions mimicking primary biliary or pancreatic tumor were seen in four, respectively. In seven, we found no obstructing lesion on CT. CONCLUSION: Biliary obstruction in patients with known primary malignancies can show atypical patterns mimicking primary pancreatobiliary malignancies on thin-section helical CT.

Adult↗
PubMedDate not supplied

Focal eosinophilic infiltration in the liver: radiologic findings and clinical course.

BACKGROUND: We investigated the radiologic findings and clinical course of focal eosinophilic infiltration in the liver. METHODS: We retrospectively reviewed computed tomographic (CT) and sonographic scans in 20 patients (18 male, two female; mean age, 50 years) with pathologically or clinically proven focal eosinophilic infiltration in the liver by two experienced radiologists in our institute from August 1995 to June 1999. We also correlated radiologic findings with peripheral eosinophil count. Radiologic and clinical findings during the follow-up (range, 2-49 months; mean, 19.5 months) also were analyzed. RESULTS: Clinical symptoms and signs included abdominal pain (n = 4), easy fatigability (n = 3), weight loss (n = 1), and peripheral eosinophilia (n = 19). Twelve patients were asymptomatic. On sonographic examinations, all lesions were seen as focal, low echoic nodules. On CT, the lesions appeared isoattenuated or low attenuated in the arterial phase and low attenuated in the portal phase, except one case that showed high attenuation in the arterial phase. The margins of most lesions appeared poorly defined. Lesions were single (n = 9) and multiple: two to five (n = 6), six to 10 (n = 3), and more than 10 (n = 2). Each lesion was smaller than 2 cm; only one was 4 cm in diameter. The distribution of the lesion was subcapsular in 14 patients and central in five. Diffuse dissemination was observed in one. Eosinophil-associated abnormality was not present in other abdominal organ in all cases. The peripheral eosinophil count correlated closely with the number but not with the size of lesions. Sixteen patients who had follow-up images showed complete (n = 14) or partial regression of the lesions with a decrease in size (n = 1) or number (n = 1) after 2-22 months (mean, 6.4 months). CONCLUSION: Focal eosinophilic infiltration in the liver had somewhat characteristic radiologic findings on sonography and CT. In the correct clinical context of peripheral eosinophilia and self-limited course, these radiologic findings may be helpful in differentiating this condition from other focal hepatic lesions.

Contrast Media↗
PubMedDate not supplied

Secretin-stimulated MRCP.

Secretin-stimulated magnetic resonance cholangiopancreatography not only facilitate the depiction of anatomic variations or morphologic changes of the pancreatic duct in the normal and diseased pancreas but also help assessing functional abnormalities of the exocrine pancreas. In this article, we illustrate findings of normal pancreas and various pancreatic diseases on magnetic resonance cholangiopancreatography after secretin stimulation.

Cholangiopancreatography, Magnetic Resonance↗
PubMedDate not supplied

Neoplasms containing normal hepatic vessels: imaging features.

BACKGROUND: We investigated the incidence and imaging features of hepatic neoplasms containing normal hepatic vessels. METHODS: Among 3183 patients with various hepatic neoplasms, we found nine patients with normal hepatic vessels traversing hepatic neoplasms. The presence of mass effect on the vessel traversing hepatic neoplasms was evaluated. Other suggestive findings of neoplasms such as altered hepatic contour, portal vein thrombosis, mass effect on extratumoral vessel, and bile duct dilatation were analyzed. RESULTS: Thirteen hepatic vessels (nine hepatic veins and four portal veins) extended through hepatic neoplasms in nine patients. Undisturbed hepatic vessels within the neoplasms were found in five patients with either primary or metastatic hepatic neoplasm. In one patient with undisturbed hepatic vessels within the neoplasm, there were no associated abnormal findings such as biliary dilatation, change of hepatic contour, or any changes involving the vessels external to neoplasms. CONCLUSION: Although rare, various primary and secondary hepatic neoplasms can have normal hepatic vessels passing through them without mass effect. However, correct diagnosis in most neoplasms would be possible with careful examination of associated findings.

Adolescent↗
PubMedDate not supplied

Preoperative evaluation of Klatskin tumor: accuracy of spiral CT in determining vascular invasion as a sign of unresectability.

BACKGROUND: To assess the accuracy of spiral computed tomography (CT) in predicting the resectability of Klatskin tumor as determined by vascular invasion. METHODS: Twenty-one consecutive patients with Klatskin tumor who had undergone laparotomy were included in this study. The preoperative thin-section (5-mm-thick) spiral CT scans of these patients were assessed for the surgical resectability of tumor by evaluating the vascular invasion. The criterion for vascular invasion indicating unresectability was the tumoral invasion of the proper hepatic artery or main portal vein or simultaneous invasion of one side of the hepatic artery and the other side of the portal vein. RESULTS: All nine patients with tumors thought to be unresectable on the basis of CT findings had tumors that were unresectable at surgery (positive predictive value, 100%). Of 12 patients with tumors thought to be resectable, six had resectable tumors (negative predictive value, 50%). Spiral CT failed to detect small hepatic metastasis (n = 1), lymph node metastasis (n = 1), extensive tumor (n = 2) and variation of bile duct (n = 2), which precluded surgical resection. CONCLUSION: Spiral CT is a reliable method for detecting vascular invasion and unresectable tumors. However, it has limitations in detecting variations of the bile duct or the intraductal extent of tumor.

Adult↗
PubMedDate not supplied

Quantitative comparison of tumor vascularity of hepatocellular carcinoma after intravenous contrast agent: conventional versus harmonic power Doppler US.

BACKGROUND: The purpose of this study was to make a quantitative comparison between conventional and harmonic power Doppler (PD) ultrasound (US) in depicting vascularity of hepatocellular carcinoma (HCC). METHODS: Ten nodular HCCs in 10 patients were prospectively examined using a 2-4-MHz convex transducer and a standardized examination protocol. Serial US images were obtained before and 20, 30, 40, 50, 60, 90, 120, 150, 180, 240, and 300 s after intravenous injection of 2 g of contrast agent using conventional and harmonic PD US. The percentage of area with Doppler signal within each HCC nodule (%PDA) was calculated in each image with a PC-based image analysis program, and the results with both US techniques were compared. RESULTS: In the majority of cases, %PDA was greater on conventional PD US than on harmonic PD US. Mean %PDA of 10 HCCs was significantly higher on conventional PD US than on harmonic PD US except at 20 s after injection. The highest values of mean %PDA were 34.9% in conventional PD US and 19.5% in harmonic PD US at 60 s after injection. CONCLUSION: Area with PD signals within the HCC is smaller and the duration of effective enhancement is shorter in harmonic PD US than in conventional PD US.

Adult↗
PubMedDate not supplied

Three-dimensional spiral CT cholangiography with minimum intensity projection in patients with suspected obstructive biliary disease: comparison with percutaneous transhepatic cholangiography.

BACKGROUND: To evaluate the diagnostic potential of spiral computed tomographic (CT) cholangiography with minimum intensity projection (minIP) in the diagnosis of patients with suspected biliary obstruction. METHODS: Nine consecutive patients with obstructive biliary disease were enrolled in this study. Spiral CT data (3-mm slice thickness, pitch 1-2:1) obtained 65 s after the start of contrast medium injection (150 mL Ultravist 370, 3 mL/s) were reconstructed at 1-mm intervals. Three-dimensional (3D) CT cholangiography with minIP (3D CTC) was generated with a Siemens software package. The quality of 3D CTC in its ability to demonstrate the anatomic detail, the level of obstruction, and the presence or absence of isolated hepatic segments was evaluated using percutaneous transhepatic cholangiography as a gold standard. RESULTS: In all patients, 3D CTC demonstrated dilated intrahepatic ducts up to tertiary branches. 3D CTC correctly diagnosed the level of biliary obstruction and demonstrated isolated segments in all patients. In determining the cause of biliary obstruction, one patient with hilar cholangiocarcinoma was misdiagnosed as having biliary invasion by hepatocellular carcinoma. CONCLUSION: 3D CTC with minIP can determine the level and cause of biliary obstruction. 3D CTC can be obtained from regular thin-section helical CT data and may be a strong competitor against diagnostic magnetic resonance cholangiography because of its superior resolution and information on adjacent soft tissues and the duct itself.

Aged↗
PubMedDate not supplied

MR cholangiopancreatography: comparison between half-Fourier acquisition single-shot turbo spin-echo and two-dimensional turbo spin-echo pulse sequences.

BACKGROUND: To compare half-Fourier acquisition single-shot turbo spin-echo spin-echo (HASTE) magnetic resonance cholangiopancreatography (MRCP) with two-dimensional turbo spin-echo (2D TSE) MRCP for imaging pancreatobiliary diseases. METHODS: Twenty-seven patients with biliary or pancreatic disease underwent MRCP on a 1.0-T scanner with a body phased-array coil. A T2-weighted HASTE sequence (18 s) and a T2-weighted 2D TSE sequence (45 s) were used during a breath-hold by the patient. The source images and maximum intensity projection images of both sequences were reviewed independently by two radiologists. RESULTS: Motion artifacts were more severely pronounced with 2D TSE sequences than with HASTE sequences (p < 0.001). All obstructions and their sites were accurately identified with both sequences. Filling defects (calculi) in bile ducts were identified in all 22 segments (100%) with HASTE-MRCP, whereas calculi in 19 of 22 segments (86%) were identified with 2D TSE-MRCP (p = 0.25). Three missed sites on 2D TSE-MRCP were intrahepatic bile ducts. CONCLUSIONS: HASTE-MRCP is superior to 2D TSE-MRCP in terms of detecting motion artifacts and visualization of the pancreatic ducts. HASTE-MRCP is comparable to 2D TSE-MRCP for visualization of the biliary ducts and their obstruction and is superior to 2D TSE-MRCP for identification of calculi in intrahepatic bile ducts.

Adult↗
PubMedDate not supplied

T2-weighted MR imaging for hepatic hemangiomas: comparison of breath-hold and non-breath-hold turbo spin-echo pulse sequences with phased-array multicoil.

BACKGROUND: We compared T2-weighted and heavily T2-weighted breath-hold turbo spin-echo (TSE) sequences with T2-weighted non-breath-hold TSE sequence to evaluate hepatic hemangiomas on magnetic resonance (MR) with a phased-array multicoil. METHODS: Twenty-two patients with 27 hemangiomas were studied at 1.0-T scanner by using T2-weighted and heavily T2-weighted breath-hold TSE sequences (18 s each) and non-breath-hold T2-weighted TSE sequences with use of a phased-array multicoil. Images were quantitatively analyzed for tumor-to-liver signal-difference-to-noise ratios (SD/Ns) and tumor-to-liver signal intensity ratios (T/Ls) and qualitatively analyzed for tumor conspicuity and motion-induced image artifacts. RESULTS: Quantitatively, T2-weighted breath-hold TSE images showed the highest SD/Ns among the three sequences, although the differences from the heavily T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were not statistically significant (p = 0.61 and 0.06, respectively). Heavily T2-weighted breath-hold TSE images showed the highest T/Ls among the three sequences. The differences from the T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were statistically significant (p < 0.001). Qualitatively, breath-hold TSE images were superior to non-breath-hold TSE images in terms of tumor conspicuity (p < 0.01) and motion artifacts (p < 0.01). CONCLUSION: T2-weighted breath-hold TSE sequence is superior to T2-weighted non-breath-hold TSE sequence in the evaluation of hepatic hemangiomas on MR with a phased-array multicoil.

Adult↗
PubMedDate not supplied

Dysplastic nodules of the liver: imaging findings.

BACKGROUND: To verify characteristic features of hepatic dysplastic nodules at different imaging modalities. METHODS: Twenty-eight patients with 37 dysplastic nodules of the liver (0.8-3.0 cm) underwent sonography (28 patients), computed tomography (CT; 24 patients), magnetic resonance (MR; 11 patients), and angiography (12 patients). Each nodule was analyzed for echogenicity, attenuation, signal intensity, and vascularity. RESULTS: Echogenicity of nodules was high in 16 (43%), homogeneous in two (6%), and low in 19 (51%) of 37 nodules. Attenuation of nodules was high in one (7%), homogeneous in four (26%), and low in 10 (67%) of 15 nodules on the arterial-phase CT images; homogeneous in five (33%) and low in 10 (67%) of 15 nodules on the portal-phase CT images; and high in four (17%), homogeneous in six (26%), and low in 13 (57%) of 23 nodules on the delayed-phase CT images. Signal intensity of nodules was high in 15 (94%) and homogeneous in one (6%) of 16 nodules on T1-weighted MR images and was homogeneous in seven (44%) and low in nine (56%) of 16 nodules on T2-weighted MR images. Vascularity of nodules was avascular in 14 (88%) and slightly vascular in two (12%) of 16 nodules. CONCLUSIONS: Hepatic dysplastic nodules show diverse imaging characteristics with different imaging techniques; however, common imaging findings of hepatic dysplastic nodules are low echo, low attenuation, and high, low, or homogeneous intensity on T1- and T2-weighted MR, and avascularity.

Adult↗
PubMedDate not supplied

Hepatic hemangioma: contrast-enhancement pattern during the arterial and portal venous phases of spiral CT.

The objective of the present study was to evaluate contrast-enhancement patterns of hepatic hemangioma according to size during hepatic arterial (30-s delay) and portal venous (65-s delay) phases of spiral computed tomography (CT). During a 10-month-period, 73 patients with 118 hemangiomas underwent two-phase spiral CT examination. The enhancement patterns of tumors were divided into four types based on the attenuation of surrounding liver parenchyma: peripherally nodular high, uniform high, iso, and low. The diameter of the tumors were <10 mm (n = 39), 11-20 mm (n = 33), and >21 mm (n = 46). Overall, the most common enhancement patterns of hemangioma were peripherally nodular high (66/118, 55. 9%) during the arterial and portal venous phases. The second most common contrast-enhancement patterns of hemangioma were uniform high (15/118, 12.7%) during the arterial and portal venous phases. In tumors smaller than 20 mm, 11 (9.3%) had low-low attenuation and two (1.7%) had iso-low attenuation during the arterial and portal venous phases, respectively. In conclusion, at two-phase spiral CT, the most common contrast-enhancement patterns of hemangioma are peripherally nodular high and/or uniform high during the arterial and portal venous phases. However, hemangiomas smaller than 2 cm may have atypical enhancing patterns including low and iso-attenuation.

Adult↗
PubMedDate not supplied

MR imaging of advanced gastric cancer: comparison of various MR pulse sequences using water and gadopentetate dimeglumine as oral contrast agents.

BACKGROUND: To evaluate clinical usefulness of oral contrast agents (gadopentetate dimeglumine and water) and to assess proper magnetic resonance (MR) imaging in evaluating advanced gastric cancer (AGC) by comparing different MR imaging techniques. METHODS: Fifteen patients with AGC were imaged with a 1.0-T MR imager and body-array coil. All patients underwent surgery or laparascopic biopsy. Fast low-angle shot (FLASH), half-Fourier single-shot turbo spin-echo (HASTE), and true fast imaging with steady-state precession time (FISP) images were obtained after ingestion of 900 mL tap water in each patient, followed by postcontrast FLASH images after additional ingestion of gadopentetate dimeglumine (Gd-DTPA). Qualitative analysis including T-staging of AGC and scoring of imaging quality and quantitative analysis were performed prospectively. RESULTS: In image quality and diagnostic accuracy of T-staging, FLASH imaging showed results slightly superior to those of other imaging modalities, and there was no great difference between using water and Gd-DTPA as an oral contrast agent. As for cancer-to-gastric lumen contrast-to-noise ratio (CNR), HASTE and true FISP imaging were superior to FLASH imaging with Gd-DTPA (p < 0.0001). In cancer-to-pancreas CNR, FLASH imaging without Gd-DTPA showed the best result. CONCLUSIONS: The use of Gd-DTPA as a positive contrast agent may not be imperative, and T1-weighted FLASH imaging in combination with true FISP imaging with ingestion of tap water can be very useful in evaluating AGC with MR imaging.

Administration, Oral↗