Magnetic Resonance Appearance of Normal Popliteal Lymph Nodes: Location and Relationship of Number, Fatty change, and Size of the Lymph nodes with Aging

PURPOSE: To investigate the location of popliteal lymph nodes and the relationship between patient age and their number, size, and the occurrence of fatty chang. MATERIALS AND METHODS: We retrospectively evaluated the magnetic resonance (MR) images of 222 patients [age range, 8-79 (mean, 47.1) years]who had undergone MRI of the knee after its internal derangement. Images were obtained in the axial, coronal, and sagittal planes. A lymph node was defined as 'observed' if it was visible in at least two planes, such as axial and sagittal or axial and coronal. With regard to location, nodes were classified as anteromedial, anterolateral, posteromedial, or posterolateral, depending upon their relationship with the popliteal vein. To determine their size, the smallest diameter was measured. RESULTS: Popliteal lymph nodes were present in 116 of 222 examinations (52.3%), and their total number was 158 (mean, 1.36). Patients'age correlated negatively with their presence (R square=0.826), and positively with the occurrence of fatty change (R square=0.840). Sixty- five of 158 lymph nodes (41.1%) were located anteromedially, 58 (36.7%) posterolaterally, 27 (17.1%) anterolaterally, and eight (5.1%) posteromedially. Their distance from the most distal femoral articular surface was 4.6+/-1.4 cm (mean +/-SD), and their mean diameter was 4.96+/-2.4 mm (mean +/-SD; range, 4-8 mm). CONCLUSION: The number of popliteal lymph nodes decreased with age, while the incidence of fatty change increased. Nodes were most frequently anteromedial or posterilateral to the popliteal vein.

Evaluation of the Pedal Artery: Comparison of Three-dimensional Gadolinium-Enhanced MR Angiography with Digital Subtraction Angiography

PURPOSE: To compare the three-dimensional gadolinium-enhanced MR angiography with digital subtraction angiography (DSA) for evaluation of the pedal artery. MATERIALS AND METHODS: In 12 extremities of 11 patients, both digital subtraction angiography (DSA) and contrast-enhanced MR angiography (CE-MR angiography) were performed during the same week. Among ten of the 11 patients, the following conditions were present: atherosclerosis (n=4), diabetic foot (n=3), Buerger's disease (n=1), calciphylactic arteriopathy (n=1) and arteriovenous malformation of the foot (n=1). The remaining patient underwent angiography prior to flap surgery. For MR angiography, a 1.5T system using an extremity or head coil was used. A three-dimensional FISP (fast imaging with steady state precession) sequence was obtained before enhancement, followed by four sequential acquisitions (scan time, 20 secs; scan interval time, 10 secs) 10 seconds after intravenous bolus injection of normal saline (total 10 cc), following intravenous adminstration of gadolinium (0.02 mmol/kg, 3 ml/sec). Arterial segments of the ankle and foot were classified as the anterior or posterior tibial artery, the distal peroneal artery, the medial or lateral plantar artery, the pedal arch, and the dorsalis pedis artery. Two radiologists independently analysed visualization of each arteraial segment and the mean of visible arterial segments in one extreminty using CE-MR angiography and DSA. RESULTS: Among 84 arterial segments, 16 were invisible at both CE-MR angiography and DSA, while 39 were demonstrated by both modalities. Twenty-six segments were visible only at CE-MR angiography and three only at DSA. CE-MR angiography displayed a higher number of arterial segments than DSA (mean, 5.42 vs. mean 3.50, respectively), a difference which was statistically significant (p<0.000). The difference between each arterial segment was not statistically significant, except for the dorsalis pedis artery (t test, p<0.000). CONCLUSION: In that it provides additional information for the planning of treatment of lower-extremity arterial disease, three-dimensional CE-MR angiography is superior to DSA for evaluation of the pedal artery.

Low-dose Contrast-enhanced Magnetic Resonance Angiography with Less than the Standard Dose of Gadolinium Chelate: Comparison with Conventional Digital Subtraction Angiography

PURPOSE: To evaluate the effectiveness of contrast-enhanced MR angiography (CEM-RA)using gadolinium chelate at less than the standard dose. MATERIALS AND METHODS: Eight patients with occlusive arterial disease underwent 16 CEMRA scans of the lower extremities following bolus injection of 0.075 mmol/kg gadolinium, using a 1.5T scanner and 3D-turbo-FLASH sequence. The arterial phase was compared with that obtained by digital subtraction angiography (DSA). After grouping arteries according to their diameter, arterial detectability (AD), stenosis grad-ing (SG), and the detectability of significant stenosis (SD) were compared. RESULTS: The AD of CEMRA showed high specificity (Sp, 98%-100%) in all groups, and sensitivity (Sn) was high (>90%) in groups I, II, and III. SG showed a correlation coefficient of 0.65* and 0.60* in groups I and II, though CEMRA tended to overesti-mate. SD was high (Sn,100%) in all groups, but Sp was low(<70%). CONCLUSION: Low-dose CEMRA is an excellent way to exclude significant arterial ob-struction in the lower extremities, even in small arteries. Stenosis grading was possible in large arteries but consideration must be paid to the technique 's overestimating characteristic.

Castleman's Disease in the Upper Extremity: A Case Report

Castleman's disease is a rare lymphoproliferative disorder of uncertain etiology which most commonly occurs in the mediastinum. We describe a case of a benign Castleman 's disease of the hyaline vascular type affecting the upper extremity, an extremely rare site of the disease.

Brodie's Abscess in Pediatric Patients: MR Imaging Findings

PURPOSE: To determine the characteristic MR imaging findings of Brodie's abscess in pediatric patients. MATERIALS AND METHODS: We retrospectively reviewed 17 pediatric patients with surgically-proven or clinically and radiologically diagnosed Brodie's abscess who had undergone T1- and T2-weighted spin-echo sequences, T2-weighted fast spin-echo sequence and gadolinum enhanced MR imaging. The MR imaging findings were analysed and classified according to the signal characteristics of the abscess and srrounding bone marrow. RESULTS: The MR imaging findings of Brodie's abscess could be classified as one of three types, as follows : Type I (10/17) was seen as a target appearance with four layers ; i.e. a center with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images; an inner rim of high signal intensity, as compared with muscle on both T1- and T2-weighted images with intense contrast enhancement; an outer rim of low signal intensity on both T1- and T2-weighted images, and a peripheral halo of low signal intensity on T1-weighted images and variable signal intensity on T2-weighted images. In type II (4/17), there was no distinction between the center and the inner rim on T1-weighted images, but a clear distinction on contrast enhanced images by intense enhancement of the inner rim. In type III (3/17), there was no distinction between the center and the inner rim on either T1-weighted or contrast enhanced images, due to diffuse enhancement of the lesions. Additional findings of Brodie's abscess include epiphyseal plate violation (8/17), linear or tubular sinus tracts (7/17), inflammatory reaction or edema of surrounding soft tissue (7/17), periosteal reaction (1/17), and pyogenic arthritis (1/17). CONCLUSION: MR imaging is a useful diagnostic tool for the characterization and determination of the extent of Brodie's abscess. Contrast enhanced MR imaging is particularly valuable for the evaluation of type II lesions.

Macrodystrophia Lipomatosa: One Case Report

Macrodystrophia lipomatosa is a rare congenital disease characterized by and increase in all mesenchymal elements, particularly fibroadipose tissue. We experienced a case of surgically proven macrodystrophia lipomatosa of index finger in a 44-year-old male. MR imaging showed hypertrophy of fibroadipose tissue that characterizesthis condition.