Sonographic Evaluation of Acute Osteomyelitis in Infants

PURPOSE: To analyze the related sonographic findings and to determine the value of sonography in establishing the diagnosis of acute osteomyelitis in infants. MATERIALS AND METHODS: The sonographic findings of eleven infants aged 10 days-4 months (mean, 45 days) with acute osteomyelitis were retrospectively evaluated. The involved bones were the femur (n=5), humerus (n=2), tibia (n=2), rib(n=1), sternum(n=1), and calcaneus(n=1). Discontinuity or destruction of cortical margins, echotexture of the metaphysis and epiphysis, the presence of subperiosteal hypoechoic lesion, adjacent soft tissue swelling, distension of the joint capsule, the echotexture of joint effusion, and dislocation or subluxation of the involved joint were evaluated. The sonographic findings were compared with the plain radiographic (n=12) and MR (n=5) findings, with special attention to the identification of the metaphyseal or epiphyseal bony lesions and the involvement of adjacent joints. RESULTS: The sonographic findings of osteomyelitis were cortical discontinuity or destruction (n=12), hypoechoic lesions with an echogenic rim in the metaphysis (n=12), subperiosteal hypoechoic lesions (n=8), soft tissue swelling (n=9), a distended hip joint, with echogenic fluid (n=5), ill-demarcated echogenic lesions in the capital femoral epiphysis (n=5), and a subluxated hip joint (n=3). Plain radiographs revealed well or ill-defined osteolytic lesions in the metaphysis, accompanied by cortical destruction (n=8), new periosteal bone formation (n=3) and reactive sclerosis (n=2). Abnormality of the femoral epiphyses and joint involvement were not detected on plain radiographs, and in four cases no abnormality was noted. MR imaging showed that at T1WI, affected bony lesions were of low signal intensity and enhanced, with high signal intensity at T2WI. In all cases, both metaphyseal and epiphyseal lesions were demonstrated at MRI, but in one of the three cases in which an epiphyseal lesion was seen at MRI, this was not detected at US. CONCLUSION: Sonography is not only more sensitive than radiography in evaluating metaphyseal bony lesions but also useful in assessing concomitant joint and epiphyseal involvement of acute osteomyelitis in infants. Sonography is, therefore, a useful additional diagnostic tool for the early detection and management of acute osteomyelitis in infants.

Disseminated BCG Infection in a patient with Severe Combined Immunodeficiency

Disseminated mycobacterial infection after bacillus Calmette-Guerin (BCG)vaccination is a very rare disorder, occurring mostly in patients with immunologic deficiency. We report a case of disseminated BCG infection in a 16-month-old girl with severe combined immunodeficiency. Plain radiographs showed multiple osteolytic lesions in the femora, tibiae, humerus, and phalanges. Abdominal sonography and CT scanning revealed multiple nodules in the spleen, and porto-caval lymphadenopathy.

Disseminated BCG Infection in a patient with Severe Combined Immunodeficiency

Disseminated mycobacterial infection after bacillus Calmette-Guerin (BCG)vaccination is a very rare disorder, occurring mostly in patients with immunologic deficiency. We report a case of disseminated BCG infection in a 16-month-old girl with severe combined immunodeficiency. Plain radiographs showed multiple osteolytic lesions in the femora, tibiae, humerus, and phalanges. Abdominal sonography and CT scanning revealed multiple nodules in the spleen, and porto-caval lymphadenopathy.

Correlation between MR Imaging and Histopathologic Findings in Acute Osteomyelitis: Experimental Study in Rabbits

PURPOSE: We compared the sequential characteristic MR findings with histopathologic findings in experimentally induced osteomyelitis of rabbits tibiae . MATERIALS AND METHODS: We induced osteomyelitis in the left tibiae of 25 rabbits by direct inoculation of E. coli. Right tibiae of the same rabbits were directly punctured with sterile needle, which were used as control groups. Spin-echo sagittal T1- and T2-weighted images(T1WI & T2WI) and gadolinium-enhanced T1-weighted sagittal images of both tibiae were obtained at 3 days, 5 days, 1 week, 2 weeks, and 4 weeks following inoculation of pathogen. MR-pathologic correlation study was done with emphasis on changes of the morphology and the MR signal intensity(SI) of marrow abscess. RESULTS: Well-defined abscesses were seen on MR 3 -5 days after pathogen inoculation and they all showed low SI on both T1 & T2WI and no enhancement. MR imaging of abscess wall, which became visible at 3 days as high SI on T1WI, gradually changed to low SI on T1WI and high SI on T2WI with diffuse enhancement according to the time sequence (17% after 3 days; 40% after 5 days; 46% after 1 week; 56% after 2 weeks; 60% after 4 weeks). The peripheral portion of the abscess, which was seen in some cases (48% after 3 days; 40% after 4 weeks), showed iso-intensity to muscle on T1WI and ill-defined high SI on T2WI with mild Gd-enhancement. Pathologically the abscesses and their walls were composed of cell debris and granulation tissue with infiltration of inflammatory cells. Fibroblasts and acute inflammatory cells in the abscess wall, which were most prominent at 3 and 5 days relatively, decreased gradually along with the development of abscess. Inner layer of the abscess wall was composed of chronic inflammatory cells, which appeared after 2 weeks of inoculation. The granulation tissue and inner chronic inflammatory cell layer became more organized feature after 4 weeks. The peripheral portion of the abscess revealed as granulation tissue. In the control group, necrosis or inflammatory cell infiltration was absent and the lesion decreased in size to remain only focal fatty change of bone marrow after 4 weeks. CONCLUSION: Central abscess composed of cell debris showed low SI on both T1 & T2WI without enhancement. Granulation tissue of the abscess wall showed more organized feature forming inner layer of chronic inflammatory cells along with the progression of osteomyelitis. Abscess showed hyperintensity on T1WI in the early stage, but changed to hypointensity on T1WI, hyperintensity on T2WI in later stage.

Correlation between MR Imaging and Histopathologic Findings in Acute Osteomyelitis: Experimental Study in Rabbits

PURPOSE: We compared the sequential characteristic MR findings with histopathologic findings in experimentally induced osteomyelitis of rabbits tibiae . MATERIALS AND METHODS: We induced osteomyelitis in the left tibiae of 25 rabbits by direct inoculation of E. coli. Right tibiae of the same rabbits were directly punctured with sterile needle, which were used as control groups. Spin-echo sagittal T1- and T2-weighted images(T1WI & T2WI) and gadolinium-enhanced T1-weighted sagittal images of both tibiae were obtained at 3 days, 5 days, 1 week, 2 weeks, and 4 weeks following inoculation of pathogen. MR-pathologic correlation study was done with emphasis on changes of the morphology and the MR signal intensity(SI) of marrow abscess. RESULTS: Well-defined abscesses were seen on MR 3 -5 days after pathogen inoculation and they all showed low SI on both T1 & T2WI and no enhancement. MR imaging of abscess wall, which became visible at 3 days as high SI on T1WI, gradually changed to low SI on T1WI and high SI on T2WI with diffuse enhancement according to the time sequence (17% after 3 days; 40% after 5 days; 46% after 1 week; 56% after 2 weeks; 60% after 4 weeks). The peripheral portion of the abscess, which was seen in some cases (48% after 3 days; 40% after 4 weeks), showed iso-intensity to muscle on T1WI and ill-defined high SI on T2WI with mild Gd-enhancement. Pathologically the abscesses and their walls were composed of cell debris and granulation tissue with infiltration of inflammatory cells. Fibroblasts and acute inflammatory cells in the abscess wall, which were most prominent at 3 and 5 days relatively, decreased gradually along with the development of abscess. Inner layer of the abscess wall was composed of chronic inflammatory cells, which appeared after 2 weeks of inoculation. The granulation tissue and inner chronic inflammatory cell layer became more organized feature after 4 weeks. The peripheral portion of the abscess revealed as granulation tissue. In the control group, necrosis or inflammatory cell infiltration was absent and the lesion decreased in size to remain only focal fatty change of bone marrow after 4 weeks. CONCLUSION: Central abscess composed of cell debris showed low SI on both T1 & T2WI without enhancement. Granulation tissue of the abscess wall showed more organized feature forming inner layer of chronic inflammatory cells along with the progression of osteomyelitis. Abscess showed hyperintensity on T1WI in the early stage, but changed to hypointensity on T1WI, hyperintensity on T2WI in later stage.

MR Evaluation of Pyo genic Osteomyelitis Involving the Epiphyses

PURPOSE: The purpose of this study was to analyze of the MR findings of the pyogenic osteomyelitis involving the epiphyses of the long bones in childhood. MATERIALS AND METHODS: Eleven childen with pyogenic osteomyelitis involving the epiphyses of the long bones were evaluated by MRI. A diagnosis of pyogenic osteomyelitis was established by biopsy and culture in eight cases and during follow-up after antibiotic treatment in three. We analyzed the involved bone, initial location, pattern, degree of growth plate involvement, degree of epiphyseal involvement, surrounding change and plain radiographic findings. RESULTS: The involved bones were the proximal femur in four cases, distal femur in two, proximal tibia in two, distal tibia in one, distal fibula in one and proximal humerus in one. The initial site of the lesion was the metaphysis in ten cases and epiphysis in one. The lesion pattern was the Brodie's abscess in six cases and osteomyelitis in five. The degree of growth plate involvement was 16-20% in five case and 5% or less in four ; the degree of epiphyseal involvement was 5% or less in four cases, 6-10% in four and 11-15% in two. All cases showed low or intermediate signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and contrast enhancement. Joint effusion adjacent to the lesion was detected in five cases. Radiographic findings of the involved epiphysis were normal in six cases, but indicated osteolytic lesion in four cases and sclerosis in one. CONCLUSION: Pyogenic osteomyelitis involving the epiphyses of the long bones in childhood usually developed from metaphyseal osteomyelitis and was combined with destruction of the growth plate.

MR Evaluation of Pyo genic Osteomyelitis Involving the Epiphyses

PURPOSE: The purpose of this study was to analyze of the MR findings of the pyogenic osteomyelitis involving the epiphyses of the long bones in childhood. MATERIALS AND METHODS: Eleven childen with pyogenic osteomyelitis involving the epiphyses of the long bones were evaluated by MRI. A diagnosis of pyogenic osteomyelitis was established by biopsy and culture in eight cases and during follow-up after antibiotic treatment in three. We analyzed the involved bone, initial location, pattern, degree of growth plate involvement, degree of epiphyseal involvement, surrounding change and plain radiographic findings. RESULTS: The involved bones were the proximal femur in four cases, distal femur in two, proximal tibia in two, distal tibia in one, distal fibula in one and proximal humerus in one. The initial site of the lesion was the metaphysis in ten cases and epiphysis in one. The lesion pattern was the Brodie's abscess in six cases and osteomyelitis in five. The degree of growth plate involvement was 16-20% in five case and 5% or less in four ; the degree of epiphyseal involvement was 5% or less in four cases, 6-10% in four and 11-15% in two. All cases showed low or intermediate signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and contrast enhancement. Joint effusion adjacent to the lesion was detected in five cases. Radiographic findings of the involved epiphysis were normal in six cases, but indicated osteolytic lesion in four cases and sclerosis in one. CONCLUSION: Pyogenic osteomyelitis involving the epiphyses of the long bones in childhood usually developed from metaphyseal osteomyelitis and was combined with destruction of the growth plate.

Diaphyseal Osteomyelitis of the Long Bone: Evaluation of Radiograph and MRI

PURPOSE: To describe the radiographic and MR characteristics of subacute diaphyseal osteomyelitis of the long bone. MATERIALS AND METHODS: We retrospectively analyzed plain radiographs and MR images in nine children and two young adults with surgically-proven diaphyseal osteomyelitis of the long bones. MR imaging was carried out before and after Gd-DPTA administration. Patients charts were reviewed for clinical and laboratory data and histologic correlation was available in all cases. RESULTS: All patients had a history of a minimum of 2 weeks' duration. All presented with an insidious onset of mild pain; they showed apyrexia and normal erythrocyte sedimentation rate. In all patients, plain radiographs showed single or multiple linear periosteal reaction with cortical irregularity. Medullary abnormality was not found except in one case which showed an abscess cavity. MR images revealed thickening or irregularity of the cortex, periosteal reaction, bone marrow signal alteration, and perilesional edema. CONCLUSION: Subacute diaphyseal osteomyelitis of the long bone is broadly based on the cortex, and elicits more sclerosis and periosteal reaction. Familarity with plain radiographs and MR features may be useful in the diagnosis of subacute diaphyseal osteomyelitis.

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.

Radiographic Features of Tuberculous Osteitis in Greater Trochanter and Ischium

PURPOSE: To evaluate, if possible, the radiographic features of tuberculous osteitis in the greater trochanter and ischium, and to determine the cause of the lesions. MATERIALS AND METHODS: We retrospectively reviewed the plain radiographic findings of 14 ptients with histologically proven tuberculous osteitis involvingthe greater trochanter and ischium. In each case, the following were analyzed : morphology of bone destruction, including cortical erosion; periosteal reaction ; presence or abscence of calcific shadows in adjacent softtissue. On the basis of an analysis of radiographic features and correlation of the anatomy with adjacent structures we attempted to determine causes. RESULTS: Of the 14 cases evaluated, 12 showed varrious degrees of extrinsic erosion on the outer cortical bone of the greater trochanter and ischium ; in two cases, bone destruction was so severe that the radiographic features of advanced perforated osteomyelitis were simulated. Inaddition to findings of bone destruction, in these twelve cases, the presence of sequestrum or calcific shadows was seen in adjacent soft tissue. CONCLUSION: Tuberculous osteitis in the greater trochanter and ischium showed the characteristic findings of chronic extrinsic erosion. On the basis of these findings we can suggest that the selesions result from an extrinsic pathophysiologic cause such as adjacent bursitis.