PubMed Health⌕ Search

Biomedical subjects

K M Yeon

Publications and source records attributed to K M Yeon.

At least 55 records · Page 3Linked to original sources
PubMed1997

MR of childhood metachromatic leukodystrophy.

PURPOSE: To investigate the MR findings of childhood metachromatic leukodystrophy (MLD). METHODS: Nine MR imaging studies in seven children (five girls and two boys, 10 to 32 months old) with MLD were evaluated retrospectively for the extent and progression of white matter abnormalities and the presence of contrast enhancement. RESULTS: All seven cases showed symmetric, confluent high signal intensity on T2-weighted images in the periventricular white matter and centrum semiovale. A posterior predominance of white matter abnormalities was noted in all cases. Although initially spared from demyelination in all cases, in one case, the subcortical U fibers were later involved in demyelination of follow-up MR studies. Other sites of involvement were the genu (n = 5) and splenium (n = 6) of the corpus callosum, the posterior limbs of the internal capsule (n = 5), the descending pyramidal tracts (n = 4), the claustrum (n = 4), and the cerebral white matter (n = 2); diffuse brain atrophy was seen in two cases. No enhancement of the lesion was seen on any of the five postcontrast examinations. A "tigroid" pattern, previously described in cases of Pelizaeus-Merzbacher disease, was noted in the centrum semiovale in six cases. CONCLUSION: In late-infantile MLD, demyelination is more prominent in the occipital region. In addition to demyelination of the periventricular white matter, common manifestations include a "tigroid" pattern and involvement of the corpus callosum, the internal capsule, and the corticospinal tract.

Brain↗
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

Quantitative lung perfusion scintigraphy in postoperative evaluation of congenital right ventricular outflow tract obstructive lesions.

Improved methods to relieve pulmonary artery stenosis have emphasized the need for an accurate noninvasive method to quantify the pulmonary blood flow. The aim of this study was to compare the roles of Tc-99m MAA perfusion lung imaging, chest x-ray, MRI, and cine-angiography for postoperative evaluation of pulmonary blood flow in patients with congenital right ventricular outflow tract (RVOT) obstructive lesions. Eleven patients underwent chest x-ray, MRI, perfusion lung imaging, and cine-angiography after corrective surgery of RVOT obstruction. The perfusion ratio on lung scans was calculated on the posterior views. The correlation coefficient of the left to right perfusion ratio measured by lung scans obtained with that by visual assessment of chest x-rays, with the most stenotic diameter ratio on MRI and on angiography being 0.57, 0.88 (P < 0.001), and 0.87 (P < 0.001), respectively. Follow-up perfusion lung scans in seven patients, before and after pulmonary artery intervention showed significantly improved perfusion ratios (0.30 +/- 0.11 to 0.70 +/- 0.22; P < 0.001), which were concordant with the clinical findings. The authors conclude that the quantitative perfusion lung scan is the noninvasive method of choice for postoperative evaluation of the pulmonary artery in congenital RVOT obstruction.

Adolescent↗
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

Involvement of the gallbladder in childhood metachromatic leukodystrophy: ultrasonographic findings.

The purpose of this study was to analyze the peculiar involvement of the gallbladder in childhood metachromatic leukodystrophy. Seven consecutive children (four boys, three girls; age range, 9 to 58 months old; mean age, 24.3 months) with biochemically confirmed metachromatic leukodystrophy were studied with abdominal ultrasonography. Four of them showed abnormal findings, such as diffuse thickening of the gallbladder wall (more than 3 mm thick), sludge-like echogenic material, or papillary polypoid ingrowth of inner wall obliterating the lumen. In childhood metachromatic leukodystrophy, the characteristic abnormality of the gallbladder on ultrasonography may serve as an ancillary diagnostic clue to supplement the clinical and MR imaging findings, facilitating the differential diagnosis from the other, similar leukodystrophies.

Child, Preschool↗
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

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

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↗
PubMed1995

A comparative study on contrast enhancement between 0.5- and 2.0-Tesla field strength in rabbit VX2 carcinomas.

RATIONALE AND OBJECTIVES: Theoretically, the degree of contrast enhancement in magnetic resonance (MR) is affected by magnetic field strength. The authors conducted this study to compare the degree of MR contrast enhancement between 0.5 Tesla (T) and 2.0 T in VX carcinomas of rabbits. METHODS: In 12 rabbits with VX2 tumors, both 0.5 T and 2.0 T MR imaging was performed within 1 day before and after intravenous injection of gadopentetate dimeglumine. Each rabbit received an initial standard dose (0.1 mmol/KG) followed by and additional standard dose (total, double dose) during the MR study at each field strength. The degree of contrast enhancement in the VX2 tumors was assessed quantitatively. RESULTS: With standard and double dose studies, overall mean tumor and muscle contrast-to-noise ratio was higher at 2.0 T than 0.5 T by 95% and 81%, respectively. The double dose study showed higher contrast-to-noise ratio than the standard dose study at both field strengths. CONCLUSIONS: Results indicate that the effect of contrast enhancement increases with field strength.

Animals↗
PubMed1995

Thoracic manifestations of Behçet syndrome: radiographic and CT findings in nine patients.

PURPOSE: To evaluate the radiographic and computed tomographic (CT) findings of patients with thoracic Behçet syndrome. MATERIALS AND METHODS: Chest radiographs and CT scans of nine patients with thoracic Behçet syndrome were retrospectively reviewed. Findings were compared. RESULTS: Radiographs of the nine patients showed mediastinal widening in five (56%), air-space consolidation in five (56%), and lung mass in three (33%). CT scans of the nine patients showed that mediastinal widening was due to thrombosis in four (44%) or narrowing of the superior vena cava in one [11%], which caused mediastinal edema; that air-space consolidation (seen on both radiographs and CT scans) was due to pulmonary hemorrhage or infarction in five (56%); and that lung mass was due to aneurysm of the right or left pulmonary artery in three (33%). In addition, CT scans showed hyperinflation in one patient. CONCLUSION: Chest radiographic findings of thoracic Behçet syndrome are variable and nonspecific. CT can be helpful in the assessment of the syndrome by showing thrombosis of the superior vena cava and characteristic aneurysms of the pulmonary arteries.

Adolescent↗
PubMed1995

Krukenberg's tumor of the ovary: MR imaging features.

OBJECTIVE: Krukenberg's tumors are metastatic tumors of the ovary. Some of these tumors had hypointense solid components on T2-weighted MR images. The purpose of this study was to evaluate the MR features of Krukenberg's tumors and to compare them with those of other solid ovarian tumors to determine whether hypointense solid components on MR images were characteristic of Krukenberg's tumors. MATERIALS AND METHODS: Twelve patients with 21 surgically proven Krukenberg's tumors of the ovary were included in the study; the tumors were bilateral in nine and unilateral in three. The MR images were studied to determine the morphologic characteristics and signal intensity patterns of the tumors (especially the presence or absence of hypointense solid components on T2-weighted images and isointense components on T1-weighted images). MR findings were correlated with histopathologic results. The MR features of 26 additional benign or malignant solid primary ovarian tumors were reviewed for comparison. RESULTS: Of the 21 Krukenberg's tumors, 14 were mostly solid and seven were entirely cystic or mostly cystic on MR images. All had sharp margins, and the oval configuration was preserved in 16. Twelve (57%) of the 21 tumors showed various amounts of hypointense solid components in random distribution or predominantly in the periphery on MR images; pathologically, these components corresponded to areas of dense collagenous stroma. MR imaging also showed that the cystic components within the masses had either well-defined or ill-defined borders. Multiseptation was noted in two masses. Of the 26 additional primary ovarian tumors, only three showed hypointense solid components on MR images. These included thecoma, fibrothecoma, and poorly differentiated adenocarcinoma. CONCLUSION: Our findings suggest that identification of hypointense solid components within an ovarian mass on T2-weighted MR images is a characteristic, although not specific, finding for Krukenberg's tumors, especially when the tumors are bilateral, have sharp margins, and have an oval configuration.

Adult↗