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Biomedical subjects

M C Han

Publications and source records attributed to M C Han.

At least 91 records · Page 5Linked to original sources
PubMed1994

Contrast enhancement of brain tumors at different MR field strengths: comparison of 0.5 T and 2.0 T.

PURPOSE: To compare the degree of MR contrast enhancement of 0.5 T and 2.0 T in various brain tumors. METHODS: MR images were studied prospectively in each of 31 patients with brain tumors (11 gliomas, 6 meningiomas, 6 neurinomas, and 8 others) before and after intravenous injection of gadopentetate dimeglumine. In every patient, both 0.5-T and 2.0-T MR studies were done within 1 week. Each patient received an initial standard dose (0.1 mmol/kg) of gadopentetate dimeglumine, followed by a subsequent 0.1-mmol/kg dose (total, double dose) in MR of each field strength. MR was done before and after each injection of the contrast agent. Degree of contrast enhancement in the lesions was assessed both visually and quantitatively. RESULTS: With standard-dose study, the tumor enhancement was visually stronger at 2.0 T than at 0.5 T in 9 gliomas. In extraaxial tumors there was visually no or minimal difference between 0.5 T and 2.0 T. Overall mean contrast-enhancement ratio and tumor and brain contrast-to-noise ratio were higher at 2.0 T than at 0.5 T by 53% and 108%, respectively. The double-dose study showed higher contrast-enhancement ratio and contrast-to-noise ratio than the standard-dose study at both field strengths, and the differences between 0.5 T and 2.0 T were almost similar to those of the standard-dose study. The degree of contrast enhancement with the standard dose at 2.0 T was comparable to that of the double dose at 0.5 T in most intraaxial tumors. CONCLUSION: The results suggest that effect of contrast enhancement increases with the field strength. Therefore, reevaluation of optimal doses of contrast media may be needed in a variety of brain lesions at each field strength.

Adolescent↗
PubMed1994

Preembolization functional evaluation in supratentorial cerebral arteriovenous malformations with superselective intraarterial injection of thiopental sodium solution.

Superselective intraarterial injections of thiopental sodium solution for evaluation of local brain function were performed before embolization in 38 consecutive patients with supratentorial arteriovenous malformations to evaluate the role of the test using thiopental sodium solution. Thiopental sodium (30-50 mg) was injected in 68 arteries (44 middle cerebral arteries, 13 anterior cerebral arteries, 7 posterior cerebral arteries, 3 external carotid arteries, and 1 thalamo-perforating artery) through superselective microcatheters just before the injection of cyanoacrylate mixture for the embolization. The test was negative in 57 arteries and there were neurologic dysfunctions in 3 of them after embolization. The neurologic deficits in these cases were caused by reflux of embolic material, spasm of the main arterial trunk, or neglected mild sensory change, respectively, and there was no real false-negative test. The embolization could not be performed due to positive test in 9 arteries. Two arteries with positive tests but acceptable symptoms were embolized and the same neurologic deficits developed immediately after embolization. There was no local arterial complication by an injection of the thiopental sodium solution. All neurologic deficits caused by positive tests developed immediately and were completely relieved within 5 min without specific management. Superselective intraarterial injection of thiopental sodium solution is a safe and reliable test for the evaluation of local brain function before embolization of supratentorial arteriovenous malformations.

Adolescent↗
PubMed1993

Tuberculous stricture of the urinary tract: antegrade balloon dilation and ureteral stenting.

In eight patients with tuberculous strictures of the urinary tract, antegrade balloon dilation and ureteral stenting was attempted. In six patients, antegrade balloon dilation was successfully performed; however, the procedure was aborted in the remaining two patients due to the failure in passing a guidewire through the stenotic lesions. In six patients in whom balloon dilation and ureteral stenting were performed, a total of nine stenotic lesions were dilated. Those were four ureteric lesions, two lesions of ureteropelvic junctions, two lesions of ureterovesical junctions, and a lesion of calyceal infundibulum. In all six patients in whom balloon dilation and ureteral stenting was successfully accomplished, intravenous urograms obtained 9-31 months after the procedure showed improvements both in contrast media excretion and in prestenotic dilatation. Antegrade balloon dilation of the urinary tract combined with ureteral stenting was an effective technique for the management of stenoses secondary to tuberculosis of the urinary tract.

Adult↗
PubMed1993

Radiological findings of human fascioliasis.

Fasciola hepatica is a trematode of herbivorous mammals. Humans are accidentally infected by the ingestion of water or raw aquatic vegetables contaminated with the metacercaria. Radiological findings of six patients with fascioliasis (five hepatic fascioliasis, one biliary fascioliasis) were analyzed. The diagnosis was based on serological testing and/or histopathologic findings of eosinophilic abscess in five patients and identification of the adult worm in one patient. The characteristic radiological features of hepatic fascioliasis were (1) cluster of microabscesses arranged in tract-like fashion (burrow tract), (2) subcapsular location of the hepatic lesions, and (3) very slow evolution of the lesion on follow-up examinations. In biliary fascioliasis, there were multiple conglomerated filling defects in the common bile duct. The authors believe that the demonstration of these features, together with peripheral eosinophilia or eosinophilic aspirate from the hepatic lesion, is very helpful in making the correct diagnosis.

Adolescent↗
PubMed1993

Radiological evaluation of pulmonary vein obstruction including two examinations by magnetic resonance imaging.

Congenital obstruction of the pulmonary vein without anomalous drainage can cause long-standing pulmonary congestion and pulmonary arterial hypertension, and it may include stenosis of individual pulmonary veins and pulmonary vein atresia. We reviewed seven cases of pulmonary vein obstruction, five of which were accompanied by other cardiac anomalies. Right pulmonary veins were involved in all seven cases; one case was bilateral. Pulmonary veins were occluded totally in five and partially in three lungs. Diagnostic pulmonary catheterization and angiography were performed. Chest radiographs of total occlusion cases showed decreased lung volume, features of pulmonary edema, interstitial lesions, and pleural changes, which were quite specific, whereas pulmonary venous dilatation was the dominant finding in partial obstruction cases. Pulmonary perfusion scan (n = 3) showed total perfusion defects in the cases with total occlusion of pulmonary veins. Magnetic resonance (MR) imaging (n = 2) demonstrated totally occluded pulmonary veins at the venoatrial junction in two lungs and membranous focal obstruction in one lung. Two children underwent pneumonectomy and had the diagnosis histologically confirmed. Although catheterization and angiography are essential for the diagnosis of pulmonary vein obstruction, MR imaging is a useful adjunct.

Adolescent↗
PubMed1993

Endodermal sinus tumour associated with benign teratoma of the common bile duct.

We report a 5-year-old boy with endodermal sinus tumour associated with benign cystic teratoma of the common bile duct (CBD). To our knowledge, there has been one case of teratoma of the CBD in the English literature with no morphological or radiological description. Our case presented a lobulated polypoid mass obstructing the distal CBD on sonography and computed tomography, which resembled the botryoid masses of rhabdomyosarcoma.

Child, Preschool↗
PubMed1993

MR findings of malignant melanoma of the vagina.

We report the MR findings in two cases of malignant melanoma of the vagina, one arising at the cervicovaginal junction which mimicked squamous cell carcinoma of the cervix and the other recurred in the vagina after previous resection. Two cases of malignant melanoma had high signal intensity on T1-weighted images and enhanced after gadopentetate dimeglumine administration.

Adult↗
PubMed1993

Tuberculous epididymitis and epididymo-orchitis: sonographic findings.

The findings at scrotal sonography in 10 patients with tuberculous epididymitis and in 2 with nontuberculous epididymitis are presented. In 6 patients with tuberculous epididymitis the testes were also involved (epididymo-orchitis). The most notable sonographic findings of tuberculous epididymitis were an enlarged epididymis, predominantly in the tail portion, and marked heterogeneity of the echo texture of the involved epididymis. Sonographic findings of associated testicular involvement consisted of a diffusely enlarged hypoechoic testis or ill defined focal intratesticular hypoechoic areas, or an irregular margin between the testis and epididymis. The sonographic findings encountered in patients with tuberculous epididymitis appear to be different from those encountered in nontuberculous epididymitis. Sonography might prove helpful in aiding the clinical distinction between these 2 forms of epididymitis and in demonstrating associated testicular involvement in tuberculous epididymitis.

Adult↗
PubMed1993

Necrotic areas in VX2 carcinoma of rabbits. Correlation of magnetic resonance imaging and pathologic appearance.

RATIONALE AND OBJECTIVES: To assess the potential of magnetic resonance imaging (MRI) for evaluating the evolution of tumor necrosis, the authors evaluated 28 VX2 carcinomas inoculated in the thigh muscles of rabbits. METHODS: MRI of VX2 carcinomas at 2.0 T was done with spin-echo technique 1 week (14 tumors) and 3 weeks (14 tumors) after the inoculation of tumor cells. T1- and T2-weighted images were obtained with 500/30 and 2,500/80 sequences; the authors also performed enhanced T1-weighted images with contrast medium. MRI and histopathologic findings were compared. RESULTS: Enhanced T1-weighted images with gadolinium-DTPA (Gd-DTPA) (dimeglumine gadopentetate) could depict necrosis in almost all tumors (27/28) and were the most sensitive technique followed by T2- and T1-weighted images. T2-weighted images best permitted the evaluation of the characteristics of necrotic areas in VX2 carcinomas, followed by T1-weighted images with contrast enhancement, and unenhanced T1-weighted images. On T2-weighted images, low-intensity areas of necrotic areas correspond to areas of early necrosis, isointense areas corresponded to areas of intermediate necrosis, and high-intensity areas corresponded to the late phase of necrosis. CONCLUSIONS: MRI is useful in depicting necrosis and characterizing different phases of necrosis in VX2 carcinomas.

Animals↗
PubMed1993

Methods for mitigating soft-tissue injury after subcutaneous injection of water soluble contrast media.

RATIONALE AND OBJECTIVES: Water soluble contrast media may cause tissue injury by extravasation during intravenous injection during various radiologic examinations. The authors attempted to find out what kind of management could mitigate tissue injury when extravasation of water soluble contrast media occurs. METHODS: Sodium and meglumine ioxithalamate was injected subcutaneously into 240 hind feet of 120 rats that were divided into six groups according to the methods of experimental management. Experimental managements included the following: no further management (control), injection of distilled water, injection of normal saline, injection of hydrocortisone, hot water application, and cold water application. Gross morphologic changes in each group were compared with those in the control group. RESULTS: Only the saline injection group showed statistically significant decrease of tissue injury compared with the control group. CONCLUSIONS: Saline injection lessens the degree of soft-tissue injury at contrast media extravasation sites in rats.

Animals↗
PubMed1993

Pulmonary paragonimiasis: clinical and experimental studies.

Pulmonary paragonimiasis is a disease caused by a lung fluke. It is endemic to East Asia, but there have been several case reports in North America. Human infestation occurs by ingestion of raw or incompletely cooked freshwater crab or crayfish infected with metacercaria. A retrospective study was performed with 78 patients who lived in South Korea and had chest radiographic findings of pleuropulmonary disease; it was subsequently shown that they had paragonimiasis. The diagnosis was based on positive results of serologic tests for Paragonimus-specific antibody or on the detection of eggs in sputum samples. Radiologic findings from these 78 patients were correlated with the pathologic and radiologic findings from a study of experimentally induced pulmonary paragonimiasis in 21 cats. Findings from the correlative study document that the typical radiologic manifestations of pulmonary paragonimiasis vary with the stage of the disease. Early findings include pneumothorax or hydropneumothorax, focal airspace consolidation, and linear opacities and are caused by the migration of juvenile worms. Later findings include thin-walled cysts, dense masslike consolidation, nodules, or bronchiectasis and are due to worm cysts.

Adult↗
PubMed1993

Pulmonary tuberculosis: CT findings--early active disease and sequential change with antituberculous therapy.

To evaluate findings of active pulmonary tuberculosis on computed tomographic (CT) scans and their sequential changes before and after antituberculous chemotherapy, 29 patients with newly diagnosed pulmonary tuberculosis and 12 patients with recent reactivation were studied prospectively. The diagnosis of active pulmonary tuberculosis was based on positive acid-fast bacilli in sputum (n = 29) and changes on serial radiographs obtained during treatment (n = 12). Twenty-six patients were followed up with CT during treatment for 1-20 months. Lungs from the cadavers of nine other patients, who died of pulmonary tuberculosis, were studied to provide a pathologic basis for diagnosis. At examination with CT, centrilobular lesions (nodules or branching linear structures 2-4 mm in diameter) were most commonly seen (n = 39 [95%]); in the 26 patients with follow-up, most of these lesions disappeared within 5 months after the start of treatment. In 11 of 12 patients with recent reactivation, CT clearly differentiated old fibrotic lesions from new active lesions. Lesions in and around the small airways appear to be the most characteristic CT feature of early active tuberculosis and may be a reliable criterion for disease activity.

Adult↗
PubMed1993

Pulmonary oil embolism after transcatheter oily chemoembolization of hepatocellular carcinoma.

The medical records of 336 patients with hepatocellular carcinoma who underwent transcatheter oily chemoembolization (TOCE) performed via the hepatic artery were retrospectively reviewed to ascertain the occurrence of symptomatic pulmonary oil embolism. In 14 patients, more than 20 mL of iodized oil was administered. In six of these 14 patients, respiratory symptoms of cough, hemoptysis, and dyspnea developed 2-5 days after TOCE, and their chest radiographs showed diffuse bilateral pulmonary parenchymal infiltrate. Their arterial partial pressure of oxygen while they breathed room air ranged from 39 to 60 mm Hg during maximum hypoxemia. The symptoms, arterial hypoxemia, and chest radiographic abnormalities completely cleared 10-28 days after TOCE in the five patients who survived. One patient died 10 days after TOCE because of respiratory arrest with a progression of pulmonary infiltrate. Although histopathologic proof is lacking, it is concluded that massive pulmonary embolization of iodized oil was the primary cause of the clinical and radiographic manifestations in these six patients.

Adult↗
PubMed1993

Cerebral sparganosis: MR imaging versus CT features.

Fourteen magnetic resonance (MR) images of 11 patients with cerebral sparganosis were reviewed retrospectively and compared with 13 computed tomographic (CT) scans of 10 of the patients. All patients underwent both nonenhanced and contrast material-enhanced MR imaging. All white matter degenerations, which were slightly hypointense on T1-weighted images and were hyperintense on T2-weighted images, were seen as areas of low attenuation on CT scans. Better contrast between normal and degenerated brain tissues was seen at MR, and two lesions were seen that were missed at CT. The parasitic granuloma was isointense to brain parenchyma on images obtained with all pulse sequences. On two follow-up MR images, location or shape of the enhancing lesions changed, suggesting migration of the worm. A new finding of hyperintensity on T1-weighted images and hypointensity on T2-weighted images in subcortical areas probably due to petechial hemorrhages was demonstrated in eight patients only at MR. Small calcific foci, which were important diagnostic clues of cerebral sparganosis, were detected in four patients only at MR, while they were seen in eight patients at CT.

Adolescent↗
PubMed1993

Perforation complicating balloon dilation of esophageal strictures in infants and children.

PURPOSE: The authors retrospectively reviewed their experience with balloon dilation of esophageal strictures in infants and children to determine the prevalence of esophageal perforation during this procedure. MATERIALS AND METHODS: Balloon dilation was performed in 32 patients with esophageal stricture due to either congenital or postoperative stenosis. The total number of procedures was 141; each patient underwent one to 12 procedures. RESULTS: Four cases of esophageal perforation occurred during balloon dilation and were detected immediately after the procedure. Perforation in three of these patients was treated nonoperatively with parenteral fluid and antibiotics, and one patient was treated surgically with resection and creation of an anastomosis. The clinical course after treatment was favorable in all cases. CONCLUSION: Although esophageal perforation during balloon dilation of benign strictures has been reported as a rare complication, four perforations were observed in 32 patients. Esophageal perforation can occur in infants and children more frequently than previously reported.

Catheterization↗
PubMed1993

Left paracardiac mass caused by dilated pericardiacophrenic vein: report of four cases.

OBJECTIVE: The pericardiacophrenic vein is a possible route of collateral circulation when either the superior or the inferior vena cava is obstructed. When the vein is dilated, it can cause an abnormal appearance on chest radiographs. We describe four such patients. MATERIALS AND METHODS: We studied four patients who had abnormalities on conventional chest radiographs due to a grossly dilated pericardiacophrenic vein, confirmed by means of venacavography, CT, or MR imaging. We analyzed the cause of the dilatation and the radiologic findings associated with the dilated pericardiacophrenic vein. RESULTS: The cause of the dilated pericardiacophrenic vein was the membranous obstruction of the inferior vena cava in all four patients. Chest radiographs revealed an undulating vascular shadow (in two cases) or a shadow of several masses (in one case) along the left border of the heart or a poorly defined haziness mimicking a pulmonary parenchymal infiltrate (in one case). A direct communication between the left hepatic vein and the left inferior phrenic vein was seen near their insertion into the inferior vena cava in three cases. Hepatic venous outflow and some of the systemic venous return were directed to this left inferior phrenic-pericardiacophrenic route. CONCLUSION: When obstruction of the inferior vena cava is clinically suspected and the chest radiograph shows abnormalities at the left paracardiac area, a dilated pericardiacophrenic vein due to obstruction in the suprahepatic portion of the inferior vena cava, most likely a membrane, should be considered in the differential diagnosis.

Adult↗