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Biomedical subjects

W K Moon

Publications and source records attributed to W K Moon.

At least 37 records · Page 2Linked to original sources
PubMed1998

Mediastinal tuberculous lymphadenitis: CT findings of active and inactive disease.

OBJECTIVE: The purpose of this study was to analyze CT findings of active and inactive disease in patients with mediastinal tuberculous lymphadenitis. MATERIALS AND METHODS: Using biopsy and culture results, we categorized 49 consecutive patients with mediastinal tuberculous lymphadenitis studied with CT scans as patients with active disease (n = 37) or patients with inactive disease (n = 12). Follow-up CT scans were obtained after antituberculous therapy in 25 patients with active disease and three patients with inactive disease. In 10 patients (seven with active disease and three with inactive disease), CT findings were analyzed and correlated with pathologic findings. RESULTS: In all 37 patients with active disease, the nodes (n = 151) varied in size (1.5-6.7 cm; mean, 2.8 +/- 1.0 cm) and had central low attenuation and peripheral rim enhancement. Calcifications within the nodes were seen in seven patients (19%). In the 12 patients with inactive disease, the nodes (n = 34) varied in size (1.0-4.7 cm; mean, 2.1 +/- 1.0 cm) but were usually smaller than nodes in patients with active disease. In the patients with inactive disease, the diseased nodes were homogeneous and without low-attenuation areas. Calcifications within the nodes were seen in 10 (83%) of the 12 patients with inactive disease. Low-attenuation areas within the nodes corresponded pathologically to areas of caseation necrosis in seven patients with active disease and in no patients with inactive disease. After treatment, enlarged mediastinal nodes in patients with active disease shrunk and low-attenuation areas within the nodes disappeared in all 25 patients. However, the findings of calcified nodes in the three patients with inactive disease did not change after 6 months of follow-up. CONCLUSION: In these 49 patients with mediastinal tuberculous lymphadenitis, CT findings of nodes with central low attenuation and peripheral rim enhancement suggested active disease, and findings of homogeneous and calcified nodes suggested inactive disease. Low-attenuation areas within the nodes had pathologic correspondence to areas of caseation necrosis and may be a reliable indicator for disease activity.

Adolescent↗
PubMed1997

Chronic mesenteric ischemia: use of in vivo MR imaging measurements of blood oxygen saturation in the superior mesenteric vein for diagnosis.

PURPOSE: To determine if dogs and humans with chronic mesenteric ischemia demonstrate a decrease in the percentage of oxygenated hemoglobin (%HbO2) in the superior mesenteric vein (SMV) after a meal. MATERIALS AND METHODS: In 10 dogs, ameroid rings were surgically implanted around the superior mesenteric arteries to create gradual stenosis. Pre- and postoperative angiograms and pre- and postprandial magnetic resonance (MR) oximetry measurements of the SMV %HbO2, with flow-independent T2 measurements of venous blood, were obtained at different times. In 10 patients with atherosclerotic disease and six patients with symptomatic chronic mesenteric ischemia, the same measurements were obtained after at least 6 hours of fasting and at 15, 35, and 45 minutes after ingestion of a liquid nutritional supplement. RESULTS: In seven dogs, the postprandial SMV %HbO2 increased an average of 2.5% +/- 0.8 before surgery and decreased an average of 6.3% +/- 2.1 when hemodynamically significant (>70%) stenosis of the superior mesenteric artery developed 7-14 days after surgery. In the 10 patients without ischemia, the SMV %HbO2 increased by 4.6% +/- 0.6, whereas in the symptomatic patients a postprandial decrease of 8.8% +/- 0.7 occurred (P < .0001). CONCLUSION: Measurement of the SMV %HbO2 with MR oximetry is a promising test for diagnosis of chronic mesenteric ischemia.

Adult↗
PubMed1997

Pulmonary tuberculosis in children: evaluation with CT.

OBJECTIVE: The purpose of our study was to describe the CT findings of pulmonary tuberculosis in children and to define indications for the use of CT. MATERIALS AND METHODS: CT findings in 41 consecutive children with confirmed tuberculosis were retrospectively analyzed by two radiologists. Chest radiographs and medical records were also reviewed to determine whether additional information provided by CT scans had altered clinical management of the disease. RESULTS: Mediastinal and hilar lymphadenopathy was seen in 34 patients (83%). In 29 of these patients, enlarged nodes had low-attenuation centers and enhancing rims. In the five other patients, enlarged nodes had calcification. Segmental (n = 12) or lobar (n = 8) air space consolidation was seen in 20 patients (49%), nodules of bronchogenic spread were seen in 12 patients (29%), and miliary nodules were seen in seven patients (17%). Bronchial (n = 15), pleural (n = 7), pericardiac (n = 1), or chest wall (n = 1) complications of tuberculosis were seen in 22 patients (54%). In eight (20%) of 41 patients, a diagnosis of tuberculosis was suggested only on CT scans, which revealed low-attenuation nodes with rim enhancement, calcifications, and nodules of bronchogenic spread or miliary nodules. These findings were not seen on chest radiographs. In 15 patients (37%), CT scans provided information that altered clinical management. Also two of these patients underwent surgery because of pleural and chest wall complications that were seen only on CT scans. CONCLUSION: Mediastinal or hilar lymphadenopathy revealed as low-attenuation nodes with rim enhancement or calcification was the most characteristic CT finding of pulmonary tuberculosis in children. CT can be useful when tuberculosis or its complications are suspected in children and the radiographic findings are normal or inconclusive.

Adolescent↗
PubMed1997

Tuberculosis of the central airways: CT findings of active and fibrotic disease.

OBJECTIVE: Management of patients with central airways tuberculosis differs according to the activity of the disease. The purpose of this study was to analyze CT findings of active and fibrotic disease in patients with central airways tuberculosis. MATERIALS AND METHODS: According to bronchoscopic findings and biopsy results, 41 patients with tuberculosis of the trachea and main bronchi were categorized as having active disease (n = 30) or fibrotic disease (n = 11). Follow-up CT scans were obtained after antituberculous therapy in 11 patients with active disease and two patients with fibrotic disease. All CT scans were retrospectively analyzed with particular attention to the locations of airway lesions, patterns of luminal narrowing, wall thickening of diseased airways, and presence of abnormal adjacent lymph nodes. RESULTS: Active disease in 30 patients involved the trachea (n = 20), the right main bronchus (n = 14), or the left main bronchus (n = 13). Seventeen patients had multiple lesions. On CT scans, these airways showed irregular (n = 24) or smooth (n = 4) narrowing in 28 patients: minimal (n = 5) or marked (n = 18) wall thickening with contrast enhancement in 23 patients: and obstruction with peribronchial cuffing in nine patients. Enlarged mediastinal lymph nodes were seen in 26 patients. Fibrotic disease in 11 patients involved the trachea (n = 6), the right main bronchus (n = 2), or the left main bronchus (n = 9). Six patients had multiple lesions. On CT scans, the airways showed smooth (n = 7) or irregular (n = 2) narrowing without (n = 5) or with minimal (n = 4) wall thickening in nine patients and obstruction without peribronchial cuffing in four patients. On follow-up CT scans, the findings for the airway lesions were almost normal in nine patients who had had initial active disease. However, the findings for airway narrowing did not change in two patients with fibrotic disease after 6 months of follow-up. CONCLUSION: Principal CT findings in our patients depended on disease stage. Central airways narrowing was seen in both active and fibrotic stages. However, in patients with active disease, CT scans showed irregular and thick-walled airways, a pattern that was reversible, whereas patients with fibrotic disease generally had smooth narrowing of airways and minimal wall thickening, a pattern that was not reversible during the follow-up period.

Adolescent↗
PubMed1996

Diminished postprandial hyperemia in patients with aortic and mesenteric arterial occlusive disease. Quantification by magnetic resonance flow imaging.

BACKGROUND: Superior mesenteric blood flow in the fasting and postprandial state in humans can be measured accurately by cine phase-contrast (CPC) magnetic resonance (MR) imaging. Postprandial flow changes associated with mesenteric arterial occlusive disease (MAOD) are unknown. METHODS AND RESULTS: We used CPC MR imaging to measure fasting and postprandial blood flow in the superior mesenteric artery (SMA) and vein (SMV) in 22 patients (mean age, 69 years) with aortic occlusive disease and MAOD and compared the results with similar measurements in 8 younger, asymptomatic volunteers (mean age, 34 years). All 22 patients had stenosis or occlusion of the splanchnic or pelvic arteries demonstrated by contrast aortography; 19 were asymptomatic and 3 had symptoms of chronic mesenteric ischemia. Mean fasting blood flow was higher in patients (4.5 mL.kg-1.min-1) than in volunteers (2.3 mL.kg-1.min-1; P < .01). However, postprandial hyperemia (mean percentage change in SMV blood flow) was less in the asymptomatic (70%; P < .001) and symptomatic patients (29%; P < .01) than in the volunteers. Postprandial SMV flow was similar to SMA flow in the patients but was significantly greater than SMA flow in the volunteers (P < .005). CONCLUSIONS: Postprandial mesenteric hyperemia is reduced in older patients with MAOD. The role of aging alone has not been determined. Fasting and postprandial flow changes in these patients may predict the onset of chronic mesenteric ischemia.

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↗
PubMed1995

Congenital fistula from ectopic accessory parotid gland: diagnosis with CT sialography and CT fistulography.

We report a case of congenital fistula from ectopic accessory parotid gland to the cheek demonstrated by CT sialography and CT fistulography. The right parotid gland was abnormally located lateral to masseter muscle. The fistula was arising from an ectopic accessory parotid gland with ectopic duct positioned anterior to masseter muscle. CT sialography and CT fistulography were very helpful in the diagnosis and surgical planning.

Cheek↗
PubMed1994

Castleman disease in the child: CT and ultrasound findings.

Castleman disease is a relatively rare disorder affecting young adults. We present the CT and ultrasonographic findings of Castleman disease in two children. In one patient with hyaline-vascular type disease, CT showed a well-enhancing mass in the right paratracheal area. In a second patient with plasma cell type disease, there was a solid, homogeneous mass in the retroperitoneal space which was poorly enhancing. Ultrasound showed a uniform hypoechogenic mass in both cases.

Castleman Disease↗
PubMed1994

Undifferentiated embryonal sarcoma of the liver: US and CT findings.

Six cases of undifferentiated embryonal sarcoma (UES) were reviewed to determine their characteristic features on ultrasonography (US) (n = 5) and computed tomography (CT) (n = 6). US demonstrated a single large, echogenic mass with some anechoic spaces. Contrast-enhanced CT scan revealed a well-demarcated low-attenuation mass with hyperdense septations of variable shape and thickness. Discrepancy of internal architecture on US and CT was one of the important characteristics of UES. CT numbers were 25-47 HU in low-attenuation areas. Enhancing peripheral rim was found in four cases and some solid portions at the periphery or adjacent to the septa were found in all cases. Two patients who had follow-up US and CT without treatment showed enhancing solid portions, changing to hypodense as the tumor grew. When compared with the pathologic findings, US showed a more accurate representation of internal architecture than did CT. Familiarity with these US and CT findings of UES of the liver will be helpful in the differential diagnosis of primary hepatic tumors in childhood.

Adult↗
PubMed1994

Castleman's disease of the mediastinum: MR imaging features.

We present the MR imaging features in two cases of mediastinal Castleman's disease of the hyaline-vascular type. T1-weighted MR images showed rounded hilar masses of intermediate or high signal intensity with areas of low signal due to vessels and calcification. On T2-weighted images, the masses were of high signal intensity. Mediastinal masses with the above signal characteristics and vascular signal voids may suggest a diagnosis of Castleman's disease.

Adult↗
PubMed1994

Germinomas of the basal ganglia and thalamus: MR findings and a comparison between MR and CT.

OBJECTIVE: The purpose of this study was to describe the MR imaging appearance of germinomas in the basal ganglia and thalamus and to compare the MR findings with CT findings. MATERIALS AND METHODS: Eleven MR studies of 10 patients with pathologically proved germinomas in the basal ganglia or thalamus were retrospectively reviewed. In nine of the 10, the MR findings were compared with CT findings. All patients were male, and all except one were in their second decade of life. All the tumors were located in paraventricular areas. RESULTS: Most of the tumors were 4-7 cm in diameter. MR images showed that the tumors were mostly cystic in five patients, mostly solid with cystic components in four, and solid without cystic components in one. The solid portion mostly was isointense relative to the cerebral cortex for all MR pulse sequences. The cystic portion was hyperintense relative to CSF on T1- and T2-weighted images. MR images showed intratumoral hemorrhage in seven patients. It appeared as an area of hyperintensity on T1- and T2-weighted images in five patients and as a fluid-fluid level with marked hypointensity on T2-weighted images in two. Hemorrhage was not visualized on CT scans in any patient. Flecked or amorphous calcifications visualized on CT scans in two patients were hardly detectable on MR images. Peritumoral edema was usually minimal. CT scans and MR images obtained after injection of contrast material both showed heterogeneous and dense enhancement in the solid portions of the tumors. CONCLUSION: MR images of germinoma in the basal ganglia and thalamus show a large paraventricular mass. Cystic areas, focal hemorrhages, and minimal surrounding edema are common. Unlike CT, MR imaging allows characterization of intratumoral hemorrhage.

Adolescent↗
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

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↗