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Biomedical subjects

M C Han

Publications and source records attributed to M C Han.

At least 55 records · Page 3Linked to original sources
PubMed1996

Tuberculous colitis. Findings at double-contrast barium enema examination.

PURPOSE: This study was undertaken to elucidate characteristic findings of tuberculous (TB) colitis at double-contrast barium enema examination (DCBE). MATERIALS AND METHODS: Twenty-five patients with TB colitis diagnosed by biopsy (n = 13) or therapeutic trial (n = 12) were included. DCBE findings were retrospectively analyzed, with special emphasis on distribution of lesions and mucosal changes. RESULTS: Involvement was asymmetric in 12. The lesion was noted more commonly in the ascending colon (n = 23), cecum (n = 21), and terminal ileum (n = 19) compared with the transverse colon (n = 15) and descending and sigmoid colon (n = 9). Skipped lesions were seen in 13 patients. Sixteen patients had multiple ulcers that were mostly transverse or circumferential in alignment (n = 11). Depth of ulcers was superficial (< 2 mm) in 9 patients and deep in 13. Two patients had fistulas. Twelve patients had inflammatory polyposis. Three patients presented with mass, and misdiagnosis of malignant tumor was made in two. Thickening, deformity, and incompetence of the ileocecal valve were frequently noted (5, 6, and 8, respectively). CONCLUSION: DCBE revealed detailed mucosal changes of TB colitis. Ulcers aligned in transverse or circumferential pattern, involvement of the right side colon, and deformity of the ileocecal valve suggest diagnosis of TB colitis.

Adolescent↗
PubMed1996

MR findings in human fascioliasis.

Fasciola hepatica is a trematode of herbivorous mammals, and man is infected by accidental ingestion of contaminated raw aquatic vegetables or water. There have been many reports on computed tomographic and cholangiographic features of human fascioliasis. However, findings of magnetic resonance (MR) imaging have not been reported. Hepatic fascioliasis produces three types of lesions in MR images arranged in tract-like fashion. The outermost area presents as an iso-signal area in T1WI, with slightly higher signal intensity in T2WI and diffuse enhancement after i.v. contrast. The second type presents as a well defined low signal area in T1WI, not enhanced, and also shows low signal intensity in T2WI. The third type has low signal intensity in T1WI, is not enhanced, and has high signal intensity in T2WI which is similar to fluid-containing inflammatory lesions such as pyogenic abscess. These findings suggest various changes associated with traumatic hepatitis caused by the migration of the worm in the liver. This diverse signal intensity can be a suggestive finding of fascioliasis.

Fascioliasis↗
PubMed1996

Spiral CT angiography of the thoracic aorta.

Computed tomographic (CT) angiography is a new minimally invasive vascular imaging modality. FOr its clinical use to increase, the advantages and potential applications of this modality must be understood. The clinical applications of CT angiography in the thoracic aorta and its branches include evaluation of congenital aortic anomalies, aortic aneurysm, aortic dissection, Takayasu arteritis, penetrating aortic atherosclerotic ulcer, traumatic aortic injury, the postoperative aorta, arch vessels, and pulmonary sequestration. The advantages of CT angiography over conventional angiography are as follows: (a) high-quality, thin axial sections that demonstrate mural changes, extraluminal pathologic conditions, and spatial relationships with adjacent organs; (b) high contrast resolution and high sensitivity for detecting calcified lesions; (c) angiographic or three-dimensional display of vascular structures and adjacent organs in any projection with a single spiral acquisition; and (d) demonstration of extrinsic causes of vascular compromise. CT angiography has the potential to replace conventional catheter angiography in the diagnosis of many pathologic conditions of the thoracic aorta.

Aortic Dissection↗
PubMed1996

Hepatic tumors: predisposing factors for complications of transcatheter oily chemoembolization.

PURPOSE: To elucidate major complications and their predisposing factors in transcatheter oily chemoembolization (TOCE) for hepatic tumors. MATERIALS AND METHODS: In a retrospective study of 351 patients (aged 26-82 years) with hepatic tumors, TOCE was performed 942 times with an emulsion of iodized oil (3-40 mL) and doxorubicin hydrochloride (20-60 mg). In 126 patients, TOCE was followed by absorbable gelatin sponge embolization. RESULTS: Complications were severe postembolization syndrome (n = 53); hepatic insufficiency (n = 20), infarction (n = 1), or abscess (n = 1); intrahepatic biloma formation (n = 3); tumor rupture (n = 3); septicemia (n = 9); coagulopathy (n = 1); gastrointestinal bleeding (n = 10); gallbladder (n = 5) or splenic infarction (n = 4); pulmonary oil embolism (n = 6); and spinal cord injury (n = 1). Important predisposing factors were major portal vein obstruction, compromised hepatic functional reserve, biliary obstruction, previous biliary surgery, excessive amount (> 20 mL) of iodized oil, hepatic arterial occlusion after repeated TOCE, and nonselective embolization. CONCLUSION: Most patients with major complications after TOCE had preexisting risk factors.

Adult↗
PubMed1996

Nutcracker syndrome: diagnosis with Doppler US.

PURPOSE: To assess diagnosis of the nutcracker (renal vein entrapment) syndrome with Doppler ultrasonography (US). MATERIALS AND METHODS: Doppler US findings in 16 patients with the nutcracker syndrome and in 18 healthy control subjects were compared. The anteroposterior (AP) diameter and peak velocity (PV) were measured at the hilar portion of the left renal vein (LRV) and at the LRV between the aorta and the superior mesenteric artery. RESULTS: The mean AP diameters of the LRV were 10.0 mm +/- 2.0 (standard deviation) and 1.9 mm +/- 1.0 (ratio, 5.0 +/- 2.3) in the patient group and 7.2 mm +/- 1.8 and 2.3 mm +/- 0.6 (ratio, 3.3 +/- 1.1) in the control group. The PVs at the two locations were 14.2 cm/sec +/- 2.5 and 110.7 cm/sec +/- 35.8 (ratio, 7.9 +/- 2.7) in the patient group and 18.6 cm/sec +/- 3.7 and 50.9 cm/sec +/- 27.9 (ratio, 2.8 +/- 1.5) in the control group. Differences in AP diameter and PV were statistically significant between the two groups (P < .01). CONCLUSION: Doppler US of the LRV with measurement of the AP diameter and PV may be useful in diagnosing the nutcracker syndrome.

Adolescent↗
PubMed1996

Power versus conventional color Doppler sonography: comparison in the depiction of vasculature in liver tumors.

PURPOSE: To compare power and conventional color Doppler sonography in the depiction of the intratumoral vasculature of hemangiomas, hepatocellular carcinomas (HCCs), and metastases of the liver. MATERIALS AND METHODS: Thirty-two patients with liver tumors (12 hemangiomas, 11 HCCs, and nine metastases) were prospectively evaluated with power and conventional color Doppler sonography by using a 2-4-MHz convex probe with 2-MHz Doppler frequency. Power Doppler sonography was performed with a 75%-88% gain. Conventional color Doppler sonography was performed with a 55%-75% gain and a pulse repetition frequency of 700 Hz. Power Doppler signals and color Doppler signals interrogated in one plane were analyzed by two radiologists, who subjectively rated power Doppler sonography as superior, equal, or inferior to color Doppler sonography. RESULTS: Overall, power Doppler sonography was superior to color Doppler sonography in 18 patients and equal in 14 (P < .01). In hemangiomas, power Doppler sonography was superior to color Doppler sonography in 10 patients and equal in two (P < .01). In HCCs, power Doppler sonography was superior to color Doppler sonography in four patients and equal in seven (P > .05). In metastases, power Doppler sonography was superior to color Doppler sonography in four patients and equal in five (P < .05). CONCLUSION: Power Doppler sonography is more sensitive than color Doppler sonography in the depiction of the vasculature of liver tumors, particularly in hemangiomas.

Adult↗
PubMed1996

Mediastinal tuberculous lymphadenitis: MR imaging appearance with clinicopathologic correlation.

OBJECTIVE: The purpose of our study was to determine the MR imaging appearance of mediastinal tuberculous lymphadenitis and to compare these findings with clinical and pathologic findings. MATERIALS AND METHODS: MR images of 23 consecutive patients with mediastinal tuberculous lymphadenitis were retrospectively analyzed with regard to homogeneity, signal intensity, and enhancement of diseased nodes after injection of contrast material (n = 19), and the imaging findings were grouped by patterns and correlated with clinical signs or symptoms and with pathologic (n = 9) findings. RESULTS: Three imaging patterns of mediastinal tuberculous lymphadenitis (113 nodes) were seen of MR images. In six patients, nodes (type 1, n = 25) were relatively homogeneous and hyperintense to muscle on both T1- and T2-weighted images and enhanced homogeneously after injection of contrast material. The patients had mild (n = 2) or no (n = 4) constitutional symptoms. The nodes corresponded pathologically to tuberculous granulomas without or with minimal necrosis. In 14 patients, nodes (type 2, n = 71) were inhomogeneous with a strong peripheral enhancement after injection of contrast material. Enhancing areas were of intermediate intensity on T1-weighted images and hypointense on T2-weighted images, and corresponded pathologically to peripheral granulation tissue within the nodes. Unenhanced areas were relatively hypointense on T1-weighted images and markedly hyperintense on T2-weighted images, and corresponded pathologically to central caseation or liquefaction necrosis within the nodes. All but one patient with type 2 nodes had moderate to severe clinical signs and symptoms. In the remaining three patients, nodes (type 3, n = 17) were homogeneously hypointense on both T1- and T2-weighted images and did not enhance after injection of contrast material. No patient with type 3 nodes had clinical signs or symptoms. The nodes corresponded pathologically to fibrocalcified nodes. CONCLUSION: The most common MR imaging appearance of mediastinal tuberculous lymphadenitis was as inhomogeneous nodes with marked hyperintensity on T2-weighted images and peripheral enhancement after injection of contrast material. This typical MR imaging appearance was mostly seen in severely symptomatic patients and was due to caseation necrosis of the tuberculous nodes.

Adolescent↗
PubMed1996

Laryngeal tuberculosis: CT findings.

OBJECTIVE: The purpose of this study was to evaluate the CT findings of laryngeal tuberculosis (TB). SUBJECTS AND METHODS: CT scans, laryngoscopic examinations, and chest radiographs of 12 patients (21-63 years old) with histologically (n = 8) or bacteriologically (n = 4) confirmed laryngeal TB were retrospectively reviewed. RESULTS: Bilateral diffuse thickening of the vocal cords and diffuse thickening and increased density of the aryepiglottic folds and paralaryngeal tissues were present in all patients. Diffuse thickening of the epiglottis was observed in seven patients. In four patients, a focal mass was noted in the anterior portions of the vocal cords (n = 3) or tip of the epiglottis (n =1). Destruction or sclerosis of cartilage was not found. Subglottic extension of the lesion was suspected in only one patient. Enlarged cervical lymph nodes were found in five patients. On laryngoscopic examinations, swelling of the vocal cords (n = 12) or epiglottis (n = 6) was present in all patients and was bilateral in nine patients. Vocal cord mobility was impaired in only one patient. Radiographic findings consistent with active pulmonary TB were present in all patients. CONCLUSION: Although the CT appearances of laryngeal TB are not specific, the possibility of laryngeal TB should be raised when bilateral and diffuse laryngeal lesions are encountered without destruction of the laryngeal architecture in patients with pulmonary TB.

Adult↗
PubMed1996

Mitochondrial myopathy-encephalopathy-lactic acidosis-and strokelike episodes (MELAS) syndrome: CT and MR findings in seven children.

OBJECTIVE: The purpose of this study was to describe the imaging characteristics of mitochondrial myopathy-encephalopathy-lactic acidosis-and strokelike episodes (MELAS) syndrome. MATERIALS AND METHODS: Twelve CT scans and 15 MR images were retrospectively reviewed in seven patients with proven MELAS syndrome. Follow-up studies were performed in all patients, and the total follow-up period ranged from 3 months to 3 years. Images were analyzed in terms of lesion distribution, enhancement pattern, presence of mass effect or atrophy, calcification, and changes on follow-up studies. RESULTS: CT and MR imaging showed multiple cortical and subcortical infarctlike lesions, which crossed vascular boundaries, and various degrees of generalized cerebral and cerebellar atrophy. Lesions were distributed in the posterior, parietal, and occipital areas in six patients, the putamen in five, the caudate nucleus in two, the thalamus in two, the frontal lobe in two, the globus pallidus in one, and the brainstem in one. Contrast enhancement was noted in two of seven cases on MR images and in three of five cases on CT scans. In the early stage, infarctlike lesions showed swelling and mass effect. Lesions resolved with or without local tissue loss in five patients, and new lesions appeared in another part of the brain in five patients. Generalized atrophy progressed in six cases and was most severe in the posterior part of the cerebral hemispheres. CONCLUSION: Our results indicate that imaging findings of multiple migrating infarctlike lesions that are not limited to a specific vascular territory, especially in the basal ganglia and posterior part of the cerebral hemisphere in children, are diagnostic of MELAS syndrome.

Brain↗
PubMed1996

Thin-section CT findings of the lungs: experimentally induced bronchial and pulmonary artery obstruction in pigs.

OBJECTIVE: The purpose of this study was to investigate whether a mosaic pattern of lung attenuation, or lobular low attenuation, is revealed on CT imaging after induction of bronchial and pulmonary artery obstruction in pigs. MATERIALS AND METHODS: Eight anesthetized and ventilated pigs, four for bronchial obstruction and four for pulmonary artery obstruction, were examined with thin-section CT. Bronchial obstruction was induced at the subsegmental level using 2- to 3-mm radiopaque silicon spheres at 14 sites. Pulmonary artery obstruction was induced at 11 sites by dislodging 2- to 3-mm silicon spheres at the level of the superior vena cava. CT scans were obtained at end expiration immediately after the obstruction in all pigs (n = 8) and after 1 day (n = 3), 3 days (n = 5), 7 days (n = 4), 14 days (n = 4), and 28 days (n = 3). RESULTS: Of the 14 sites of bronchial obstruction, six sites (43%) on the immediate scans showed a lobular distribution of low attenuation distal to the spheres, which changed to atelectasis, consolidation, or normal on follow-up CT. Of the four sites that did not show changes in lung attenuation on immediate CT scans, two sites showed lobular low attenuation after 1 day. The mean attenuation value +/- SD for the lobular low attenuation was -737 H +/- 122 and that of the adjacent lung was -522 H +/- 53 (p = .0077). None of the pulmonary artery obstruction sites showed visible change in lung attenuation, and mean attenuation values for obstructed sites and unobstructed sites did not show significant differences when scanned as many as 28 days after the immediate scans. CONCLUSION: Lobular low attenuation on thin-section CT was induced by bronchial obstruction, but we found no change in lung attenuation due to obstruction of the pulmonary arteries as many as 28 days after the immediate scans.

Animals↗
PubMed1996

Fibrosing inflammatory pseudotumors involving the skull base: MR and CT manifestations with histopathologic comparison.

PURPOSE: To describe the MR and CT features of fibrosing inflammatory pseudotumors of the skull base region, and to document the MR signal intensity of the lesions with histopathologic comparison. METHODS: We reviewed the MR and CT studies of five patients with pathologically proved fibrosing inflammatory pseudotumor involving the skull base. Unenhanced spin-echo T1- and T2-weighted and contrast-enhanced T1-weighted MR images were obtained at 0.5 T in three patients and at 1.5 T in two patients. MR findings were correlated with histopathologic findings in all five cases, and the enhancement pattern was compared with CT findings in three cases. RESULTS: In three cases, the cavernous sinus was involved unilaterally, with adjacent extracranial infiltrative masses. In one case, both orbits, the cavernous sinuses, and the tentorium were involved with diffuse infiltrative lesions. One patient had an infiltrative nasopharyngeal mass; and in all five patients, MR images showed localized involvement of the skull base, with bone marrow replaced by tumor. The soft-tissue lesions were hypointense on T2-weighted images in all five cases and showed homogeneous contrast enhancement. Histopathologic studies revealed scanty inflammatory cell infiltration with densely fibrotic background in all cases. The hypointensity of the lesions on T2-weighted images seemed to be related to the degree of fibrosis. CONCLUSION: Fibrosing inflammatory pseudotumor shows characteristic MR findings of infiltrative lesion with bone destruction and hypointensity on T2-weighted images. The lack of mobile protons due to the fibrotic background and/or high cellularity of the lesions may be the reason for their hypointensity and weaker enhancement on MR images.

Adult↗
PubMed1995

Characterization of focal hepatic tumors. Value of two-phase scanning with spiral computed tomography.

BACKGROUND: Spiral computed tomography (CT) allows imaging of the liver during the peak contrast material levels due to the capability of fast data acquisition. The objective of this study was to evaluate the usefulness of two-phase spiral CT in the differential diagnosis of focal hepatic tumors. METHODS: One hundred two patients who had hepatic tumors (211 nodules; 149 hepatocellular carcinomas [HCCs], 36 metastases, and 26 hemangiomas) underwent two-phase spiral CT with 10-mm collimation at 10 mm/second table speed and 120 mL of contrast material injected at the rate of 3 mL/second. Computed tomography images of the hepatic arterial phase and late (equilibrium) phase were obtained at 35-second and 180-second delays, respectively. The enhancement patterns of tumors were divided into six types and were compared with the attenuation of surrounding liver parenchyma: totally high, peripherally high, centrally high, mixed, iso, and low. RESULTS: The common enhancement patterns of HCC in two-phase spiral CT were totally high in the arterial phase and low (n = 63, 42%) or iso (n = 28, 19%) in the late phase. Metastasis showed peripherally nonnodular high attenuation (n = 9, 25%) or low attenuation (n = 9, 25%) in the arterial phase and low attenuation in the late phase, followed by totally high attenuation in the arterial phase and iso in the late phase (n = 6, 17%). Hemangiomas showed totally or peripherally nodular enhancement in the arterial and late phases (n = 23, 89%). In distinguishing hemangiomas from malignant tumors, totally high or peripherally nodular high attenuation in the late phase was the most useful contrast enhancement pattern (96% of hemangioma vs. 0% of malignant tumors). In distinguishing HCCs from metastases, a combination of contrast enhancement pattern of totally high attenuation in the arterial phase and low in the late phase was the most useful contrast enhancement pattern (42% of HCCs vs. 0% of metastases). The predictability of differentiation between hemangiomas and malignant tumors and between HCCs and metastases was 99% and 90% with spiral CT, respectively. CONCLUSIONS: Two-phase spiral CT is useful in the differential diagnosis of focal hepatic tumors with evaluation of contrast enhancement patterns.

Adult↗
PubMed1995

Cystic intrapulmonary lymphangioma: HRCT findings.

We report a rare case of cystic intrapulmonary lymphangioma involving the left lung, which presented with pneumothorax and respiratory distress in a 6-month-old infant. Chest radiographs showed a multicystic lesion in the left lung mimicking the features of congenital cystic adenomatoid malformation of the lung. The lesion appeared on high-resolution CT (HRCT) as a multiseptate, air-filled cystic lesion in the left hilar area. Associated HRCT findings were thickening of interlobular septa and bronchovascular bundles in the left lung and the presence of peripheral pulmonary vessels within cystic lesions in the apex of the left lung. HRCT findings correlated well with histopathologic findings. We suggest that these associated findings may be helpful in distinguishing this condition from other cystic lung diseases and that this entity should be included in the differential diagnosis of multicystic lung lesions.

Cystic Adenomatoid Malformation of Lung, Congenita↗
PubMed1995

CT of pulmonary tuberculosis.

CT scans in patients with primary tuberculosis commonly show lymphohematogenous spread of the disease, whereas those of postprimary (reactivation) tuberculosis commonly show bronchogenic spread. High-resolution CT (HCRT) is extremely helpful in understanding pathomorphological changes, mode of spread of the disease, and sequential morphological change after antituberculous chemotherapy, and possibly in diagnosing activity of the disease. Centrilobular 2- to 4-mm nodules or branching linear lesions representing intrabronchiolar and peribronchiolar caseation necrosis are the most common findings of early bronchogenic spread of tuberculosis. The 2- to 4-mm centrilobular nodules may coalesce to form 5- to 8-mm nodules or lobular consolidation. Cavitation usually begins at the central portion of a lobule around the bronchioles. Resolution of the tuberculous lesions occurs with antituberculous chemotherapy, resulting in varying degrees of fibrosis, bronchovascular distortion, emphysema, and bronchiectasis. HRCT may show both paracicatricial irregular emphysema and lobular emphysema. CT findings of early miliary dissemination commonly include ground-glass opacification with barely discernible nodules that show discrete miliary nodules thereafter. CT also is useful in the evaluation of long-standing destructive pulmonary lesions and tracheobronchial tuberculosis.

Humans↗
PubMed1995

Doppler sonography in experimentally induced acute renal failure in rabbits. Resistive index versus serum creatinine levels.

RATIONALE AND OBJECTIVES: The purpose of this study is to investigate the temporal relation between the change in the resistive index (RI) from renal Doppler sonography and that of serum creatinine values in the course of experimentally induced reversible acute renal failure (ARF) in rabbits. METHODS: Reversible ARF was induced in 10 New Zealand white rabbits by injecting a glycerol solution (6.0 mL/kg) into the thigh muscle. Doppler sonography was performed before injection, and 6, 12, and 24 hours, and 3, 5, 7, and 14 days after injection of glycerol. Blood samples for measuring serum creatinine levels were obtained in the same time sequence. Three rabbits, which died during the course of the experiment, were excluded from the study group. RESULTS: The RI elevated rapidly after glycerol injection, peaked at 12 hours, and then decreased to normal values by 7 days. Conversely, serum creatinine values were elevated and peaked at 1 day and then decreased to normal by 14 days. The change in the RI preceded the change in serum creatinine levels in the course of reversible ARF. There was a weak linear correlation between RI and serum creatinine levels, with a correlation coefficient of 0.33. CONCLUSION: Doppler sonography with measurement of resistive index may be useful in predicting the course of ARF.

Acute Kidney Injury↗