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Biomedical subjects

M C Han

Publications and source records attributed to M C Han.

At least 145 records · Page 8Linked to original sources
PubMed1991

Paraquat poisoning: findings on chest radiography and CT in 42 patients.

The purpose of this study is to describe the radiologic manifestations of paraquat-induced pulmonary damage, with special emphasis on the sequential changes seen with this condition. Paraquat is a herbicide that has toxic effects on the lungs, liver, and kidneys. Progressive respiratory failure is a frequent cause of death. We analyzed retrospectively 42 patients with a history of paraquat ingestion and abnormal findings on chest radiographs. Radiographic changes during the first week after ingestion included diffuse consolidation (26/39), pneumomediastinum with or without pneumothorax (15/39), and cardiomegaly with widening of the superior mediastinum (8/39). Small cystic and linear shadows began to appear at the end of the first week and were the preponderant parenchymal abnormality after 2-4 weeks. Focal honeycombing was the major parenchymal abnormality after 4 weeks. High-resolution CT of the lung 9 months after paraquat exposure revealed localized fibrosis containing small cysts. Our study shows that the pulmonary manifestations of paraquat poisoning begin with air-space consolidation, which then leads to end-stage lung.

Accidents↗
PubMed1991

Paroxysmal nocturnal hemoglobinuria. Case report of MR imaging and CT findings.

A case of paroxysmal nocturnal hemoglobinuria (PNH) is presented in which MR imaging and CT findings were characteristic. The signal intensity of renal cortex was lower than that of medulla on both T1- and T2-weighted imaging. On CT without contrast enhancement the attenuation of renal cortex was higher than that of renal medulla. These findings at MR imaging and CT were the results of a deposition of hemosiderin in the cells of proximal convoluted tubules, and were helpful for diagnosis of PNH.

Female↗
PubMed1990

Results of treatment of stage I-III breast cancer in black Americans. The Cook County Hospital experience, 1973-1987.

Whether the prognosis for black women with breast cancer differs from that of nonblack women remains controversial. The treatment results of 526 black women who received definitive therapy for Stage I-III breast cancer at Cook County Hospital, 1973 through 1987 are presented. The 5-year and 10-year projected survival rates for 272 node-negative patients (83.9% and 76.6%, respectively) and for 72 node-positive nonadjuvant treated patients (58.1% and 35.2%, respectively) are similar to those reported in the literature for nonblack patients. Adjuvant therapy improved the projected relapse-free (P = 0.0744) and overall survival curves (P = 0.0448) for 182 node-positive patients compared with nonadjuvant patients. The greatest benefit was seen for patients greater than 50 years of age with one to three positive nodes. The incidence of estrogen and progesterone receptors was found to be similar to those reported for nonblack patients. Once breast cancer has been diagnosed and appropriately treated, there appear to be few differences in the natural history of breast cancer between black and nonblack patients.

Adenocarcinoma↗
PubMed1990

Clinical utility of partial flip angle T2-weighted spin-echo imaging of the brain.

To assess the clinical usefulness of partial flip angle (PFA) spin-echo (SE) brain imaging, a total of eighty patients were examined with both conventional double echo T2-weighted SE (2500/30, 80/90 degrees/one excitation) and PFA double echo SE (1200/30, 70/45 degrees/two excitations) on 2.0T system. Two comparative studies were performed: (1) in 65 patients PFA SE technique was compared with conventional SE without flow compensating gradients, and (2) in 15 patients the former was compared with the latter with flow compensating gradients. Imaging time was nearly identical in each sequence. In both studies we found that PFA T2-weighted SE images were almost identical to those obtained with the conventional SE technique in the contrast characteristics and the detection rate of the abnormalities (100%, 85/85 lesions), and more importantly, PFA SE revealed few flow artifacts in the brain stem, temporal lobes and basal ganglia which were frequently seen on conventional SE without flow compensating gradients. Additionally, PFA SE images demonstrated no suppression of CSF flow void in the aqueduct which was commonly seen on conventional SE with flow compensating gradients. In overall image quality, the PFA SE images, particularly the second echo images, were almost comparable with those of conventional SE with flow compensating gradients. A flip angle of 45 degrees seems to be close to Ernst angle, the angle at which maximum signal occurs, for a given TR of 1200 msec for CSF and most of the abnormalities containing higher water content.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Gd-DTPA enhanced MR imaging in intracranial tuberculosis.

Twenty-six patients with intracranial tuberculosis (Tb) (10 with acute meningitis, 5 with chronic meningitis, 5 with meningitic sequelae and 6 with localized tuberculoma(s)) were examined with MR before and after Gd-DTPA enhancement (0.1 mmol/kg), using 2.0T superconducting unit, and the images were retrospectively analyzed and compared with CT scans. Without Gd-DTPA enhancement, the MR images were generally insensitive to detection of active meningeal inflammation and granulomas. The signal intensity of granulomas was usually isointense to gray matter on both T1- and T2-weighted images, whether they were associated with diffuse meningitis or presented as localized tuberculoma(s). A few granulomas showed focal hypointensity on T2-weighted images. Calcifications seen on CT of the meningitic sequelae group usually appeared markedly hypointense on all spin-echo sequences. On Gd-DTPA enhanced T1-weighted images, abnormal meningeal enhancement indicating active inflammation was conspicuous, and the granulomas often appeared as conglomerated ring-enhancing nodules, which seems to be characteristic of granulomas. Thin rim enhancement around the suprasellar calcifications were observed in two out of 5 patients with meningitic sequelae. Compared with CT, MR detected a few more ischemic infarcts, hemorrhagic infarcts, meningeal enhancement and granulomas in the acute meningitis group, but missed small calcifications in the basal cisterns well shown on CT in the sequelae group. Otherwise, MR generally matched CT scans. MR imaging appears to be superior to CT in evaluation of active intracranial Tb only if Gd-DTPA is used, while CT is better than MR in evaluating meningitic sequelae with calcification.

Adolescent↗
PubMed1990

Mosaic pattern of encapsulated hepatocellular carcinoma: correlation of magnetic resonance imaging and pathology.

Internal architecture of an encapsulated hepatocellular carcinoma (HCC) was studied with magnetic resonance imaging and histologic correlation. The capsule of HCC showed low intensity relative to liver on both T1- and T2-weighted images. The T1-weighted images were superior to the T2-weighted images in delineating the capsule of HCC. The tumor showed a mosaic pattern, which was a configuration composed of multiple compartments of different intensities, reflecting viable tumor nodules and a necrotic portion. Viable tumor nodules, composed of trabeculae of polygonal cells resembling the normal liver cell with well-formed sinusoids, showed low intensity relative to liver on T1-weighted images and high intensity on T2-weighted images. The necrotic portion, composed of coagulation of amorphous, thick eosinophilic material without hemorrhage or inflammatory reaction, showed low intensity relative to liver on both T1- and T2-weighted images. The T2-weighted images were superior to the T1-weighted images in demonstrating the mosaic pattern of HCC.

Adult↗
PubMed1990

Experimental tissue damage after subcutaneous injection of water soluble contrast media.

Various water soluble contrast media (WSCM) were injected subcutaneously into 970 hind feet of 485 rats. Gross morphologic changes were seen after the injection and analyzed as a function of various physicochemical characteristics of WSCM. The WSCM of larger volume, higher osmolality, higher iodine content, and meglumine salts rather than sodium salts caused more severe tissue damage; younger rats showed more severe tissue damage by WSCM of high osmolality.

Animals↗
PubMed1990

Caroli disease: central dot sign in CT.

Two adults with communicating cavernous ectasia of the biliary tract (Caroli disease) are described. Both patients had the pure form of the disease, characterized by saccular dilatation of intrahepatic bile ducts, multiple intrahepatic calculi, absence of portal hypertension, and associated cystic renal disease. Computed tomographic (CT) scans of the liver showed tiny dots with strong contrast enhancement within dilated intrahepatic bile ducts (the central dot sign). These intraluminal dots on CT scans corresponded to intraluminal portal veins on sonograms, findings indicating portal radicles surrounded by dilated intrahepatic bile ducts.

Adult↗
PubMed1990

Uterine cervical carcinoma: comparison of CT and MR findings.

Thirty patients with uterine cervical carcinoma underwent computed tomography (CT), magnetic resonance (MR) imaging, and surgical exploration. MR imaging was superior to CT in visualization of the tumor. MR imaging had an accuracy of 77% in the assessment of thickness of cervical stromal invasion. The accuracy rates of these modalities for parametrial evaluation were 78% for clinical evaluation, 70% for CT, and 92% for MR imaging. The overall accuracy rates for tumor staging were 70% for clinical evaluation, 63% for CT, and 83% for MR imaging. MR imaging is superior to clinical evaluation and CT in parametrial evaluation and the staging of uterine cervical carcinoma.

Adult↗
PubMed1990

Hemorrhagic fever with renal syndrome: MR imaging of the kidney.

Magnetic resonance (MR) imaging of the kidneys was performed in 14 patients with a severe form of hemorrhagic fever with renal syndrome (HFRS), a major public health problem in Far Eastern Asia. To the authors' knowledge, this is the first report of renal assessment with MR imaging in HFRS. Three MR imaging studies were done while patients were in the oliguric phase, 19 were done during the diuretic phase, and three were done during the convalescent phase. The authors differentiated the cortex and the medulla in all 21 T1-weighted examinations and all 25 T2-weighted examinations. Seven T1-weighted examinations (33%) and 20 T2-weighted examinations (80%) showed low signal intensity along the outer portion of the medulla, which thus enabled differentiation from the inner medulla. Low signal intensity along the medulla (especially the outer medulla) on T2-weighted images, possibly representing medullary hemorrhage, is fairly constant and characteristic on MR images of the kidneys in patients with HFRS.

Adult↗
PubMed1990

Small hepatocellular carcinoma versus small cavernous hemangioma: differentiation with MR imaging at 2.0 T.

Eighteen small hepatocellular carcinomas (HCCs) and 38 hemangiomas less than 5 cm in diameter were studied with magnetic resonance (MR) imaging at 2.0 T. Relatively T1-weighted spin-echo (SE) 500/30 (repetition time msec/echo time msec) images and proton-density 2,000/30 images showed nonspecific contrast-to-noise ratios (C/Ns) and intensity ratios in HCCs and hemangiomas. On T2-weighted 2,000/60, 90, 120, 150, and 180 images, hemangiomas had significantly greater C/N and intensity ratios than HCCs (P less than .05). The SE 2,000/180 sequence showed the greatest difference in tumor-liver intensity ratios between small HCCs and hemangiomas, followed by the SE 2,000/150 sequence, but there was no statistically significant difference between the two pulse sequences. However, the SE 2,000/180 sequence is limited in the number of sections obtainable for routine clinical liver imaging. The findings indicate that the SE 2,000/60 sequence is optimal for the detection of small HCCs and hemangiomas and that the SE 2,000/150 sequence is optimal for distinguishing small HCCs from hemangiomas at 2.0 T.

Adult↗
PubMed1990

Lobar bronchioloalveolar carcinoma: "angiogram sign" on CT scans.

The authors reviewed computed tomographic (CT) scans of 12 patients with lobar bronchioloalveolar carcinoma. Seven patients had consolidation of the entire lobe, and five patients had segmental consolidation. After contrast material was administered intravenously, the consolidated lung typically appeared on the scan as an area of homogeneous low attenuation, within which were enhanced branching pulmonary vessels (the CT angiogram sign). To evaluate the specificity of this sign in the discrimination of bronchioloalveolar carcinoma, CT scans of 26 patients who had lobar consolidation from other diseases were randomly mixed with the CT scans of 11 patients with bronchioloalveolar carcinoma. Two independent observers who were unfamiliar with the cases classified 10 and nine of the 11 patients with bronchioloalveolar carcinoma, respectively, as positive for bronchioloalveolar carcinoma by applying the CT angiogram sign, and classified as negative 25 and 23 of the 26 patients without bronchioloalveolar carcinoma, respectively, for an overall specificity of 92.3%. The angiogram sign appeared on the CT scan because of the low-attenuating consolidation, which was caused by the production of mucin or other fluid and the intact bronchovascular framework within the tumor.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1990

Mitral stenosis: evaluation with MR imaging after percutaneous balloon valvuloplasty.

To evaluate the pathoanatomic findings of mitral valve stenosis and changes after percutaneous balloon valvuloplasty (PBV), magnetic resonance (MR) imaging was performed in 23 patients. The patients were imaged with a 2.0-T system within 1 week before and 3-10 days after PBV. The angle of the interatrial septum was measured on the transverse image to facilitate a successful transseptal puncture. On MR images, the mean transverse and anteroposterior diameters of the left atrium at the level of the aortic root in the ventricular diastolic phase decreased significantly after PBV. Areas of flow-related intraluminal signal intensity detected in the left atrial cavity of 17 patients (74%) before the procedure disappeared in 15 patients after the procedure. Other MR imaging findings after PBV were the disappearance of intraluminal signal intensity in the pulmonary artery, normal curvature of the interatrial and interventricular septa, and pericardial effusion as a complication. MR imaging was thought to provide useful information before and after PBV in patients with mitral stenosis.

Adolescent↗
PubMed1990

Gd-DTPA-enhanced MR imaging of the brain in patients with meningitis: comparison with CT.

Plain and Gd-DTPA-enhanced MR images of the brain were obtained in 18 consecutive patients with meningitis (eight with tuberculous, five with bacterial, three with viral, and two with fungal infections); the MR images were compared with CT scans. MR images were obtained on a 2.0-T superconducting unit with both T1- and T2-weighted pulse sequences before injection and with a T1-weighted sequence after injection of Gd-DTPA (0.1 mmol/kg) in all patients. In tuberculous meningitis, MR imaging depicted ischemia/infarct, hemorrhagic infarct of basal ganglia, meningeal enhancement at either basal cistern or convexity surface of brain, and associated small granulomas in a few more patients than CT did. In bacterial meningitis, primary foci of extracranial inflammation (i.e., mastoid, paranasal sinuses) and adjacent intracranial lesions including localized dural inflammation, subdural fluid collection, and/or brain parenchymal lesions were demonstrated much better on MR than on CT. Otherwise, MR images generally matched the CT scan. Although the plain MR images, both T1- and T2-weighted, were the most sensitive in delineating ischemia/infarct, hemorrhage, and edema, they were not as specific as Gd-DTPA-enhanced T1-weighted images and postcontrast CT scans in defining the active inflammatory process of the meninges and focal lesions precisely. We conclude that if Gd-DTPA is used, MR imaging appears to be superior to CT in the evaluation of patients with suspected meningitis. Precontrast MR is needed to delineate ischemia/infarct, edema, and subacute hemorrhage.

Adolescent↗
PubMed1989

Unusual MR manifestations of neurocysticercosis.

MR and CT features of neurocysticercosis are variable and depend fundametally on the stage in evolution of the infection, location, number and size of the worm. The authors retrospectively evaluated MR images obtained on a 2.0T superconducting unit in 22 neurocysticercosis patients and observed various MR features including some new findings. A variety of MR findings are presented with special reference to six case reports. The features include: (1) a large simple cyst containing both internal septations and a scolex; (2) suprasellar racemose cysts mimicking other cysts, (3) a fourth ventricular cyst readily depicted by aid of CSF flow-void in the sagittal plane; (4) degenerating cysts showing "white target" appearance; (5) granulomatous lesions having a "black target" appearance; and (6) a meningitic form showing Gd-DTPA enhancement of basal cisterns and of a subacute infarct.

Adolescent↗
PubMed1989

Sonographic characteristics of small hepatocellular carcinoma.

Fifty-four lesions of small hepatocellular carcinoma under 5 cm in diameter detected by real-time sonography were reviewed to characterize the sonographic feature. Twenty-nine lesions were smaller than 3 cm in diameter and 25 were between 3 and 5 cm in diameter. Sonographic characteristics of hepatocellular carcinoma were peripheral hypoechoic halo (52%), lateral shadow (26%), posterior acoustic enhancement (44%), and mosaic pattern (24%) of the mass. Small tumors less than 3 cm in diameter showed a hypoechoic pattern in half of the cases, whereas most of the tumors between 3 and 5 cm in diameter showed a hyperechoic or mixed pattern. Posterior acoustic enhancement was commonly seen in small tumors less than 3 cm in diameter, while a mosaic pattern was commonly seen in large tumors between 3 and 5 cm in diameter. These results suggest that sonography might be useful for the characterization of small hepatocellular carcinoma.

Adult↗
PubMed1989

Hepatosplenic tuberculosis with hypersplenism: CT evaluation.

Hepatosplenic tuberculosis of macronodular form is extremely rare. We present one case of hepatosplenic tuberculosis with its appearance on computed tomography (CT). The CT findings of hepatosplenic tuberculosis were multiple, well-defined, round or ovoid, low-density masses with a range of +35 to +45 HU. Lymphadenopathy in the abdominal and mediastinal area and pleural effusion were also found. Although CT does not confirm a diagnosis of hepatosplenic tuberculosis, it is a valuable examination to support the diagnosis and define the extent of disease.

Female↗