Six patients with twenty histologically proven neurilemmomas of the extremities were studied using magnetic resonance(MR) imaging. The size, number, signal intensity on spin-echo T1WI(TR 500-650ms/TE 14-25ms)and gradient -echo (TR 200-600ms/TE 14-20ms; flip angle 25-30)image, enhancement pattern, detectability of nerve of origin, nerve-lesion relationship, and presence of a capsule were analyzed. The masses ranged from 1 to 12cm in longitudinal diameter and originated from the median nerve, ulnar nerve, sciatic nerve, radial nerve, and tibial nerve. All the nerve tracts except for those of 5 lesions, which could not be detected due to their small diameter, were visualized as low intensity tubular structures. All visible nerve tracts were situated along the periphery of the lesion and this finding was considered to be specific for neurilemmona. All neurilemmomas were isointense with the surrounding muscle on spin-echo T1WI and hyperintense on gradient-echo image. After a GD-DTPA injection, all masses showed moderate or marked enhancement and more prominent inhomogeneity than that on nonenhanced scan. In 19 out of 20 lesions(95%), a low signal intensity capsule surrounding the masses could be seen. Four of the six patients showed multiple masses, which was unusual as neurilemmoma usually arises as a solitary mass. In conclusion, the MR findings, especially the eccentric location of the mass lesion from the nerve of origin and the presence of a capsule, were useful in making a diagnosis of neurilemmoma of the extremity and that multiple neurilemmomas were not uncommon.
Diagnosis ; Extremities* ; Gadolinium DTPA ; Humans ; Median Nerve ; Neurilemmoma* ; Radial Nerve ; Sciatic Nerve ; Tibial Nerve ; Ulnar Nerve

Detection and evaluation of early soft tissue changes are important in rheumatoid arthritis or other jointdiseases. The most important factors for radiologic demonstration of soft tissue changes are resolving power andthe optimization of contrast differences between structures representing skin and subcutaneous tissue densities.Phantom study was done by using combination of immersion technique and mammography to get the most reliable methodfor improvement of soft tissue contrast without deterioration of resolution. Clinical application was also done in5 normal volunteers and 5 rheumatoid patients. The results indicate that soft tissue contrast, especially betwenskin and subcutaneous tissues can be significantly imporved with combination of immersion technique andmammography with 50% ethanol in both phantom and clinical study.
Arthritis, Rheumatoid ; Clinical Study ; Ethanol ; Healthy Volunteers ; Humans ; Immersion ; Mammography ; Radiography ; Skin ; Subcutaneous Tissue

Mach bands, a visual phenomenon resulting from lateral inhibitory impulsess in the retina, are recognized aslucent or dense lines at the borders of different radiographic densities. A number of clinical situations have been described in which Mach bands may cause difficulty in radiographic diagnosis. Photodensitometric measurement of the film can differentiate the true change in film density from the Mach band which is an optical illusion. Authors present several examples of photodensitometric tracings of Mach bands, with the brief review of themechanism of their production.
Diagnosis ; Optical Illusions ; Retina

In adenomatous polyposis coli there are many colonic and extracolonic manifestations, and various combinations of these induce different clinical presentations and syndromes. We experienced a unique case of adenomatous polyposis of the large intestine and stomach in a 39-year-old man. In the colon, small cell neuroendocrine carcinoma rather than adenocarcinoma had developed, which did not contain adenomatous or carcinomatous foci. The adenomatous polyps in the colon were all small and sessile with no cancerous or precancerous change two years after the resection of the symptomatic gastric adenomas, even though the gastric adenomas were larger and showed dysplastic change. We think this case is another variant of adenomatous polyposis syndrome.
Adenocarcinoma ; Adenoma

A thymoma often occurs in patients with myasthenia gravis, but the development of multiple thymoma is very rare. The authors report the radiologic and pathologic findings of multiple invasive thymoma in a 59-year-old male with myasthenia gravis.
Humans ; Male ; Middle Aged ; Myasthenia Gravis* ; Thymoma*

PURPOSE: To determine the MR imaging findings for the differentiation of tuberculous spondylitis(TS) and pyogenic spondylitis(PS) with emphasis on the shape and MR signal characteristics of paraspinal mass. MATERIALS AND METHODS: We obtained spin-echo T1- and T2-weighted MR images of 63 surgically proved cases of TS and 15 casesof PS. Gadopentetate dimeglumine(Gd)-enhanced T1-weighted MR images in 37 cases of TS and in all 15 cases of PS were also obtained. Paraspinal mass formation, the size, shape and Gd-enhancing pattern of this mass and penetration of paraspinal ligaments by inflammatory tissue were analyzed. RESULTS: Paraspinal mass was found inboth TS(63/63) and PS(9/15). The mean longitudinal dimension of this mass was 4.3 vertebral body heights in TS and1.8 in PS. The margin of the mass was smooth in TS due to subligamentous spread of inflammation, while PS showedan irregular margin and invaded the para-aortic or para-caval space(9/15) due to penetration of inflammatory tissue through the paraspinal ligament. In the lumbar spine, however, TS showed focal penetration of the paraspinal ligament and formed psoas abscesses. After Gd enhancement, TS showed irregular thick or uniformly thinrim enhancement(35/37), suggesting caseation necrosis and cold abscess, while PS showed diffuse enhancement, suggesting abundant granulation tissue. CONCLUSION: MR imaging findings helpful for the differentiation of TS andPS were size, shape and enhancing pattern of paraspinal mass and penetration of paraspinal ligament by inflammatory tissue.
Abscess ; Body Height ; Granulation Tissue ; Inflammation ; Ligaments ; Magnetic Resonance Imaging* ; Necrosis ; Psoas Abscess ; Spine ; Spondylitis*

No abstract available.
Ataxia* ; Brain Stem Neoplasms* ; Mesencephalon*

A patient with a history of asthma underwent computed tomography (CT). With a soft tissue window (width 330, level 30) the scan of the neck did not show any lesion within the airway lumen, but with a lung parenchymal window(width 1300, level -500), we were able to find a low attenuationg endotracheal mass lesion measuring -320HU. A bronchoscopy was performed and a polypoid mass approximately 2cm in diameter was found within the tracheal lumen. An endoscpic biopsy was not performed due to the risk of bleeding and the bronchoscopy was inconclusive for tissue diagnosis. CT, however, provided a definitive diagnosis by demonstrating fat within the tumor on the lung window.
Asthma ; Biopsy ; Bronchoscopy ; Diagnosis ; Hemorrhage ; Humans ; Lipoma* ; Lung ; Neck

A patient with a history of asthma underwent computed tomography (CT). With a soft tissue window (width 330, level 30) the scan of the neck did not show any lesion within the airway lumen, but with a lung parenchymal window(width 1300, level -500), we were able to find a low attenuationg endotracheal mass lesion measuring -320HU. A bronchoscopy was performed and a polypoid mass approximately 2cm in diameter was found within the tracheal lumen. An endoscpic biopsy was not performed due to the risk of bleeding and the bronchoscopy was inconclusive for tissue diagnosis. CT, however, provided a definitive diagnosis by demonstrating fat within the tumor on the lung window.
Asthma ; Biopsy ; Bronchoscopy ; Diagnosis ; Hemorrhage ; Humans ; Lipoma* ; Lung ; Neck

Neurilemmomas of the extremities are nerve sheath tumors involving peripheral nerves of the extremities. We analyzed MR images of 16 surgically proved tumors in 12 patients and compared the MR images with gross pathologic specimens in two tumors (2/16). Spin echo T1-weighted images were obtained in all the patients but T2-weighted images were obtained in six patients with a gradient echo technique. Gadolinium dimeglumine enhanced T1-weighted images were obtained in 11 patients (15/16). Signal on T1-weighted images was iso or slightly higher than that of the adjacent muscles. Signal on T2-weighted images ranged from homogeneous high to heterogeneous. After Gadolinium injection, all the 15 tumors showed enhancement. Small sized tumors were enhanced homogeneously but there was a tendency tobe enhanced heterogeneously to the central portion with peripheral rim enhancement as the size of the tumors increased. Pathologically, the enhanced portion was correlated the with solid protion was correlated the with solid portion of the tumors. Also encapsulation of the mass (12/16), suspended nerve strings (9/16) and bony erosion (1/16) were detected. MR characteristics of neurilemmoma include heterogeniety on enhanced T1 and T2 weighted images, encapsulation, and suspended nerve strings. Signal heterogeneity on enhanced T1 and T2 weignted images may be attributed to the variable cellularity, cystic changes, vascularity and focal hemorrhage of the tumors.
Extremities ; Gadolinium ; Hemorrhage ; Humans ; Magnetic Resonance Imaging* ; Muscles ; Nerve Sheath Neoplasms ; Neurilemmoma* ; Peripheral Nerves ; Population Characteristics