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

Brachycephaly is a kind of craniosynostosis. Because of premature closure of the coronal suture, the skull is shorter in the anteroposterior diameter but is widened with a high vault and the occiput and forehead are flattened. Diabetes insipidus had been reported in oxycephaly. We have experienced a case of central diabetes insipidus associated with brachycephaly. A brief review of related literatures is included in this report.
Craniosynostoses* ; Diabetes Insipidus ; Diabetes Insipidus, Neurogenic* ; Forehead ; Skull ; Sutures

Subdural empyema is a fulminating, purulent, bacterial infection located between the dura and arachnoidal membrane. Early diagnosis, adequate antibiotic therapy and surgical treatment played important roles in the successful management of subdural empyema. Subdural empyema can develop secondary to sinusitis, otitis media, meningitis, trauma or craniotomy. Subdural empyema in infants commonly develops secondary to infected subdural effusion associated with purulent meningitis. The incidence of this complication of meningitis in infants is approximately 2%. We report a case of subdural empyema concomitant with bilateral subdural effusion, which was successfully treated with surgical intervention and antibiotic therapy.
Arachnoid ; Bacterial Infections ; Craniotomy ; Early Diagnosis ; Empyema, Subdural* ; Humans ; Incidence ; Infant* ; Membranes ; Meningitis* ; Otitis Media ; Sinusitis ; Subdural Effusion*

To evaluate the role of MR in the examination of Legg-Calve-Perthes(LCP) disease, we retrospectively analysed the signal intensity of the osseous lesion, thickness of the articlar cartilage, change of surrounding soft tissue. Joint effusion and femoral head containment in 32 cases of LCP diseases in 27 patients. The bony lesion was limited witin the epiphysis in 19 cases(59%) and extended to the physis and metaphysis in 13 cases(41%). The epiphyseal lesion showed homogeneous(26/32) or heterogeneous(6/32) low signal intensity(ST) on T-1 weighted images(T1WI). And homogeneous (16/28) or heterogeneous(12/28)low SI on T-2 weighted images(T2WI). The metaphyseal lesion showed low SI(13/13) on T1WI, and low(9/11) or iso(3/11)SI on T2WI. Associated metaphyseal cyst showed low SI on T1WI and high SI on T2WI. An althought physeal involvement(13/32) was indistinct, the lesion showed increased SI on both T1 and T2WI. Thickening of articular cartilage(32/32), swelling f the ligamentum teres(7/32), synovial hypertrophy(7/32) and joint effsion(27/32) were demonstrated. Lateral subluxation of the femoral head on coronal image indicated incongruity of the femoral head in 25cases(78%) We conclude that MR is an useful tool for the diagnosis as well as treatment planning in LCP disease.
Cartilage ; Containment of Biohazards ; Diagnosis ; Epiphyses ; Head ; Humans ; Joints ; Legg-Calve-Perthes Disease* ; Retrospective Studies

PURPOSE: Algorithms to get cross-sectional bone density pattern(transverse histogram) to predict the loosening of hip prosthesis using DXA(Dual X-ray Absorptiometry) have been developed. We performed this study to analyze the correlation between radiologic findings and densitometric pattern of the THRA(Total Hip Replacement Arthroplasty) patients. MATERIALS AND METHODS: Thirty-six hips of 32 THRA patients were evaluated. The duration between THRA and DXA was from 1 year 7 months to 15 years. On transverse histogram, the periprosthetic bone density patterns were classified as 3 types;type I, rigid fixation in 17, type II, definite loosening in 8, and type III, partial loosening in 11 cases. Surgical findings, plain X-ray findnings and transverse histogram using DXA were correlated. RESULTS: Among 14 cases performing revision for acetabular prosthesis loosening, 5 cases revealed loosening of fernoral stems while 9 cases revealed rigid fixation of femoral stems. Sensitivity was 100% for either plain X-ray or DXA. Specificity was 88%, 77% for plain X-ray and DXA respectively. CONCLUSION: This preliminary study reveals that periprosthetic bone density pattern on transverse histogram on DXA may be useful in the evaluation of the loosening. However, further study will be needed for clinical application.
Acetabulum ; Arthroplasty, Replacement, Hip* ; Bone Density ; Hip ; Hip Prosthesis ; Humans ; Prosthesis Failure ; Sensitivity and Specificity

PURPOSE: To assess the spinal canal and neural foraminal stenosis associated with spondylolisthesis on MR imaging. MATERIALS AND METHODS: We retrospectively analysed MR findings of 63 cases of spondylolisthesis(degenerative type:23 cases, isthmic type:40 cases) regarding the type and grade of spondylolisthesis, prensence or absence of associated spinal canal stenosis, and the severity of associated neural foraminal stenosis. RESULTS: Central canal stenosis were more frequent in degenerative type(91%) than isthmic type(33%), and more frequent in grade II spondylolisthesis of degenerative type(100%) and isthmic type(89%) than in grade spondylolisthesis of degenerative type(45%) and isthmic type(20%). There was positive correlation between the severity of neural foraminal stenosis and the grade of spondylolisthesis, whereas there was no significant difference between degenerative and isthmic types. CONCLUSION: Degenerative spondylolisthesis were frequently associated with central canal stenosis more than isthmic type. When the grade of spondylolisthesis was higher, it was more frequently associated with central canal stenosis and severe neural foraminal stenosis.
Constriction, Pathologic* ; Magnetic Resonance Imaging ; Retrospective Studies ; Spinal Canal ; Spondylolisthesis*

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

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