Yang Guk Chung

Necrotizing Fasciitis versus Pyomyositis: Discrimination with Using MR Imaging

Objective We wanted to evaluate the MR findings for differentiating between necrotizing fasciitis (NF) and pyomyositis (PM). Materials and Methods The MR images of 19 patients with surgically confirmed NF (n = 11) and pathologically confirmed PM (n = 8) were retrospectively reviewed with regard to the presence or absence of any MRI finding criteria that could differentiate between them. Results The patients with NF had a significantly greater prevalence of the following MR findings (p < 0.05): a peripheral band-like hyperintense signal in muscles on fat-suppressed T2-weighted images (73% of the patients with NF vs. 0% of the patients with PM), peripheral band-like contrast enhancement (CE) of muscles (82% vs. 0%, respectively) and thin smooth enhancement of the deep fascia (82% vs. 13%, respectively). The patients with PM had a significantly greater prevalence of the following MRI findings (p < 0.05): a diffuse hyperintense signal in muscles on fat-suppressed T2-weighted images (27% of the patients with NF vs. 100% in the patients with PM), diffuse CE of muscles (18% vs. 100%, respectively), thick irregular enhancement of the deep fascia (0% vs. 75%, respectively) and intramuscular abscess (0% vs. 88%, respectively). For all patients with NF and PM, the superficial fascia and muscle showed hyperintense signals on T2-weighted images and CE was seen on fat-suppressed CE T1-weighted images. The subcutaneous tissue and deep fascia showed hyperintense signals on T2-weighted images and CE was seen in all the patients with NF and in seven (88%) of the eight patients with PM, respectively. Conclusion MR imaging is helpful for differentiating between NF and PM.

MR differentiation of low-grade chondrosarcoma from enchondroma

PURPOSE To evaluate magnetic resonance (MR) imaging for the discrimination between low-grade chondrosarcoma and enchondroma. MATERIALS AND METHODS MR images of 34 patients who were confirmed with low-grade chondrosarcoma or enchondroma were retrospectively reviewed. After review of medical records, MR findings in 18 patients with low-grade chondrosarcoma and 16 patients with enchondroma were compared. MR images were retrospectively reviewed for the lesion location (central or eccentric; epiphysis, metaphysic, or diaphysis), margin, contour, mineralized matrix, endosteal scalloping, cortical expansion, cortical destruction, soft tissue mass formation, and periosteal reaction. Signal intensity, the patterns of contrast enhancement (unilocular or multilobular), soft tissue mass, and adjacent abnormal bone marrow and soft tissue signal were also reviewed. Statistical analysis was performed with chi-square test. RESULTS The patients with low-grade chondrosarcoma had a significantly higher incidence of MR findings (P<.05): predominantly intermediate signal on T1-weighted images [72% (13/18) in low-grade chondrosarcoma vs. 25% (4/16) in enchondroma], multilocular appearance on contrast-enhanced T1-weighted images [83% (15/18) vs. 44% (7/16)], cortical destruction [33% (6/18) vs. 0% (0/16)], a soft tissue mass [28% (5/18) vs. 0% (0/16)], adjacent bone marrow and soft tissue abnormal signal [22% (4/18) vs. 0% (0/16)], and an involvement of the epiphysis or flat bone [56% (10/18) vs. 19% (3/16)]. CONCLUSION MR imaging shows helpful features for differentiating low-grade chondrosarcoma from enchondroma.

MR Findings of the Osteofibrous Dysplasia

Objective The aim of this study was to describe MR findings of osteofibrous dysplasia. Materials and Methods MR images of 24 pathologically proven osteofibrous dysplasia cases were retrospectively analyzed for a signal intensity of the lesion, presence of intralesional fat signal, internal hypointense band, multilocular appearance, cortical expansion, intramedullary extension, cystic area, cortical breakage and extraosseous extension, abnormal signal from the adjacent bone marrow and soft tissue and patterns of contrast enhancement. Results All cases of osteofibrous dysplasia exhibited intermediate signal intensity on T1-weighted images. On T2-weighted images, 20 and 4 cases exhibited heterogeneously intermediate and high signal intensity, respectively. Intralesional fat was identified in 12% of the cases. Internal low-signal bands and multilocular appearance were observed in 91%. Cortical expansion was present in 58%. Intramedullary extension was present in all cases, and an entire intramedullary replacement was observed in 33%. Cortical breakage (n = 3) and extraosseous mass formation (n = 1) were observed in cases with pathologic fractures only. A cystic area was observed in one case. Among 21 cases without a pathologic fracture, abnormal signal intensity in the surrounding bone marrow and adjacent soft tissue was observed in 43% and 48%, respectively. All cases exhibited diffuse contrast enhancement. Conclusion Osteofibrous dysplasia exhibited diverse imaging features ranging from lesions confined to the cortex to more aggressive lesions with complete intramedullary involvement or perilesional marrow edema.

Differentiation of focal indeterminate marrow abnormalities with multiparametric MRI.

To explore magnetic resonance imaging (MRI) parameters from intravoxel incoherent motion diffusion‐weighted imaging (IVIM‐DWI), multiecho Dixon imaging (ME‐Dixon), and dynamic contrast‐enhanced imaging (DCE) for differentiating focal indeterminate marrow abnormalities

Tips Under the Skin: A Simple Modification of Extension Block Pinning for Mallet Fractures

Pins exposed out of the skin after surgery for mallet fractures keep patients from washing their hands. The authors buried the tips of all pins under the skin while performing extension block pinning for 14 patients with mallet fractures. The patients were allowed to wash their hands 4 to 5 days postoperatively, without any dressing or splinting. The pins were removed at a mean of 8 weeks postoperatively. Solid union was achieved in all 14 fractures. No pull-out or subsidence of the pin was observed. No patient developed infection or other pin-related complications. Mean extension lag at final follow-up was 4°. [Orthopedics. 2018; 41(2):e299-e302.].