MR Evaluation of "Metaphyseal" Change in Legg-Calve-Perthes Disease

PURPOSE: To determine the metaphyseal changes occurring in Legg-Calve-Perthes(LCP) disease using MRI. MATERIALS AND METHODS: Between 1992 to 1999, 80 LCP patients (87 hips) underwent MR imaging and plain radiography. All MR images were reviewed, bone marrow signal intensity, the size and location of the metaphyseal cyst and its epiphyseal necrosis grade determined. RESULTS: Metaphyses were abnormal in 43hips (49%), while bone marrow edema was present in 28 (32%) and a metaphyseal cyst in 30 (34%). Metaphyseal cysts were classified as either 'true' (n=9) or 'false' (n=21) according to the enhancement pattern. The maximum diameters of true and false cysts were 1.1+/-0.3 cm and 1.1+/-0.4 cm, respectively. Their most commom location was the anterior column; a true cyst occurred there in 7cases (78%), and false cyst in 16 (76%). Using the Waldenstrom classification, seven of the nine hips wih a true cyst (78%), were found to be at the avascular stage and 15 of the 21 with a false cyst (71%) were at the fragmentation stage. Seven of these nine (78%) and 19 of these 21 (90%) were Catterall grade IV. CONCLUSION: According to the findings of MR imaging, the metaphyseal changes occurring in LCP disease were bone marrow edema and metaphyseal cyst. This latter was visualized mainly in the anterior column and severely affected hip, and was classified as 'true' or 'false'.

Serial MR findings of Metaphyseal Cyst in Legg-Calve'-Perthes Disease: A Case Report

Metaphyseal cysts are common findings in Legg-Calv Perthes(LCP) disease, though usually disappear within 6-12 months. Several studies have described the MR imaging findings of these cysts, though serial MRI findings have not been documented. In this report, therefore, we report the serial MRI results of metaphyseal cyst in LCP patients.

Contrast-Enhanced Fat-Suppression MR Imaging of Avascular Necrosis of Femoral Head

PURPOSE: To evaluate the findings and role of contrast-enhanced fat suppression MR imaging in avascular necrosis(AVN) of the femoral head. MATERIALS AND METHODS: In 15 patients with AVN of the femoral head, MR T1-weighted and T2-weighted images and contrast-enhanced fat-suppression T1-weighted images were obtained, and the findings were re-viewed. Early and advanced groups were classified on the basis of clinical findings and imaging, and the en-hancement pattern was classified as either type I, rim enhancement; type II, surrounding diffuse enhance-ment; type III, intralesional enhancement; or type IV, II + III. RESULTS: Twenty-four cases of AVN of the femoral head were detected; in nine patients, lesions were bilateral. Eight cases occurred in the early group and 16 in the advanced. All eight in the early group showed the "double line sign" on T2-weighted images, with a type-I enhancement pattern. In the advanced goup, type II(8/16) and type IV(8/16) enhancement patterns were seen. Among the cases showing the type-IV pattern, the intrale-sional enhancing area showed low signal intensity on T1-weighted images and isosignal intensity on T2 weighted in one case, and low signal intensity on T1-weighted images and high signal intensity on T2-weight-ed in the other cases. There was no difference in the extent of the disease before and after enhancement. CONCLUSION: Contrast-enhanced fat-suppression MR images may be helpful in evaluating the extent of AVN of the femoral head and predicting the histopathologic findings of the disease

Measurement of Necrotic Portion in Legg-Clave-Perthes Disease: Comparison of MRI Volume Measurement Method andCatterall Classification

PURPOSE: The purpose of this study was to evaluate the extent of necrosis of the femoral head inLegg-Clave-Perthes (LCP) disease. This involved the use of MRI, followed by volume measurement and the use of theCatterall classification system; the difference between the grade obtained using each of these approaches was thendetermined. MATERIALS AND METHODS: We retrospectively reviewed 28 hip-joint MR images on which a diagnosis of LCPdisease had been based. According to the necrotic portion of femoral head, and on the basis of the catterallclassification, LCP was graded 1 to 4, as follows: Grade I=0~ <25%; II=2 5~ <50%; III=50~ <75; IV=75-100%. Using atransparent paper on which 1mm squares had been drawn, the necrotic area of each MR image was measured; thefollowing equation was then used to calculate the volume of the necrotic portion: volume=necrotic area x slicethickness. On the basis of this measurement, each femoral head was graded and the results were compared with thoseobtained using the Catterall classification. RESULTS: In 24 joints(85.7%), grades according to the Catterallclassification and MRI volume measurement were not the same. As compared with the volume measurement method, useof the Catterall classification led to grade overestimation in 18 joints (64.3%) and underestimation in six(21.4%). CONCLUSION: The grade according to the Catterall classification was different from that obtained usingthe volume measurement method. This study thus indicates the need for a new system of classifying LCP diseasebased on the volume measurement method and using MR imaging.

Multiple Bony Lesions other than Femoral Heads on

PURPOSE: To evaluate the clinical significance of the multiple increased uptake lesions other than in femoral heads as seen on whole body bone scan in patients with avascular necrosis of femoral heads. MATERIALS AND METHODS: One hundred and seventy three patients with clinical diagnosis of avascular necrosis of fthe emoral head underwent a bone scan using Tc-99m MDP. Increased uptake lesions other than in femoral heads were evaluated, including frequency and common sites of involvement, and correlated with clinical information and plain radiographic findings. Two hundred patients without AVN, who had undergone a bone scan, were included as a control group. RESULTS: Increased uptake lesions in extrafemoral head locations were found in 36 of 173 patients(20.8% ; the location of 79 lesions was other than the femoral head, This result is statistically different from patients without avascular necrosis of femoral head(p<0.0001). The most common site of involvement was the knee joint area(62.5%). Other lesions were located in the mid-shafts of the long bones of the lower extremities, calcaneus, proximal humerus, etc., in order of decreasing frequency. Plain radiographs of 17 lesions were nonspecific, except for three lesions showing definite changes associated with avascular necrosis. The risk factors included alcoholism, the prolonged use of steroids, renal transplantation, herbal medication and working as a working as deep-sea diver. Most patients did not complain of pain, except for two with irreversible osteonecrotic changes as seen on plain radiograph. CONCLUSION: in patients with avascular necrosis of the femur, increased uptake lesions other than in the femoral head as seen on bone scan, may represent the early stage of osteonecrosis, which shows a characteristic appearance on bone scan. In order to avoid possible misdiagnoses of multiple extrafemoral lesions as bony metastasis or traumatic lesions, in patients with avascular necrosis of the femur these should be carefully evaluated.

Multiple Bony Lesions other than Femoral Heads on

PURPOSE: To evaluate the clinical significance of the multiple increased uptake lesions other than in femoral heads as seen on whole body bone scan in patients with avascular necrosis of femoral heads. MATERIALS AND METHODS: One hundred and seventy three patients with clinical diagnosis of avascular necrosis of fthe emoral head underwent a bone scan using Tc-99m MDP. Increased uptake lesions other than in femoral heads were evaluated, including frequency and common sites of involvement, and correlated with clinical information and plain radiographic findings. Two hundred patients without AVN, who had undergone a bone scan, were included as a control group. RESULTS: Increased uptake lesions in extrafemoral head locations were found in 36 of 173 patients(20.8% ; the location of 79 lesions was other than the femoral head, This result is statistically different from patients without avascular necrosis of femoral head(p<0.0001). The most common site of involvement was the knee joint area(62.5%). Other lesions were located in the mid-shafts of the long bones of the lower extremities, calcaneus, proximal humerus, etc., in order of decreasing frequency. Plain radiographs of 17 lesions were nonspecific, except for three lesions showing definite changes associated with avascular necrosis. The risk factors included alcoholism, the prolonged use of steroids, renal transplantation, herbal medication and working as a working as deep-sea diver. Most patients did not complain of pain, except for two with irreversible osteonecrotic changes as seen on plain radiograph. CONCLUSION: in patients with avascular necrosis of the femur, increased uptake lesions other than in the femoral head as seen on bone scan, may represent the early stage of osteonecrosis, which shows a characteristic appearance on bone scan. In order to avoid possible misdiagnoses of multiple extrafemoral lesions as bony metastasis or traumatic lesions, in patients with avascular necrosis of the femur these should be carefully evaluated.

Marrow Pattern in the Proximal Femoral Metaphysis of Patients with Osteonecrosis of Femoral Head and Normal Subjects: Comparison on MR Images

PURPOSE: To predict early risk of osteonecrosis of the femoral head by comparison of the bone marrow pattern of the proximal femoral metaphysis(PFM) in normal subjects and patients with osteonecrosis of the femoral head on T1-weighted magnetic resonance (MR) images. MATERIALS AND METHODS: The authors retrospectively reviewed T1 (TR525/TE 25 msec) weighted coronal MR images of 67 hips with osteonecrosis and 65 normal hips in 39 patients with osteonecrosis of the femoral head and in 27 normal subjects. On the basis of bright signal intensity of fat, the proportion of remaining hematopoietic marrow in PFM was subdivided into 4 grades (0 to 3) by two radiologists. No evidence of remaining hematopoietic marrow was assigned grade 0, and grades 1, 2 and 3 represented scanty, moderate, and prominent hematopoietic marrow, respectively. Grades 0 and 1 were collectively defined as "predominantly fatty", grades 2 and 3 as "predominantly hematopoietic". The frequency of the predominantly fatty marrow in PFM was analyzed in relation to three age groups(<25,25-50,50<) and both sexes. RESULTS: The overall frequency of predominantly fatty marro in PFM was higher in hips with osteonecrosis than in normal hips (p<0.001). Especially in the male population under the age of 50, the frequency was apparently higher in hips with osteonecrosis, compared with normal hips (p<0.001). However, the male population aged over 50 or female population showed no statistically significant difference in our series. CONCLUSION: In proximal femoral metaphysis with osteonecrosis of the femoral head, fatty marrow conversion occurs apparently earlier than in normal subject. T1-weighted MR imaging could therefore be useful in predictiong early risk of osteonecrosis of the femoral head because of early fatty marrow conversion of the proximal femoral metaphysis.