Biomedical subjects

Wei-Ming Chen

Publications and source records attributed to Wei-Ming Chen.

28 records · Page 2Linked to original sources

PubMed2004

Do we get a "real" alignment of knee in the preoperative planning of high tibia osteotomy: a prospective study of reproducibility.

BACKGROUND: Precise preoperative measurement of knee alignment is needed to calculate the accurate angle of correction at proximal tibia osteotomy for medial gonarthrosis. METHODS: We performed a prospective study to compare the reproducibility of measuring the mechanical and anatomical axes. Thirty-two patients (32 knees) with medial compartment osteoarthritis to be treated with proximal tibia osteotomy were included in this study. Preoperatively, whole lower limb roentgenographs were obtained twice, and 2 independent radiologists measured the mechanical and anatomical axes from each roentgenograph. RESULTS: Measurement of mechanical and anatomical axes had a mean variability of 2.22 and 1.88 degrees, respectively, which was not statistically significant (p = 0.267) in the assessment of reproducibility. With the anatomic axis, however, we found 0.61 degree of variability to the roentgenographic procedures and 1.30 degree to the radiologists (p = 0.007). With the mechanical axis, the corresponding findings were 1.30 degree and 1.02 degree (p = 0.167). Despite the relative small number of patients in this series, errors in measurement of the anatomical axis seem mostly to originate from different radiologists, whereas errors in measurement of the mechanical axis seem to originate from both the radiologists and the procedures. The maximum variability in measuring both axes was 3 degrees, which is highly significant for a reliable calculation of the wedge when performing proximal tibia osteotomy. CONCLUSIONS: We suggest that, for accuracy and economy, measurement of the anatomical axis might be better. Furthermore, by measuring either mechanical or anatomical axis, the errors originating from roentgenographic measurement of knee alignment should be considered in preoperative planning.

Algorithms↗

PubMed2004

Periacetabular giant cell tumor treated with intralesional excision and allograft reconstruction.

Giant cell tumors of the acetabulum are uncommon lesions. Their diagnosis is often delayed due to their slow progression, late onset symptoms and easily been obscured by bowel gas in plain pelvic radiographs. The tumor size is always very large at the time of diagnosis, with major nerve and joint involvement. Management of such tumor remains challenging to orthopedic surgeons. Between 1992 and 1999, 3 acetabular giant cell tumors were diagnosed and managed at our institution. The treatment modality was intralesional tumor excision with structural allograft reconstruction. The margin of tumor was routinely managed with high-speed burring and phenol application. All 3 patients were free of local recurrence at a mean follow-up of 89 months. Postoperative palsy of sciatic nerve occurred in 1 patient, but no complications such as wound infection or fracture were seen. The nerve palsy recovered completely 1 year later. The final functional outcome of the 3 patients was excellent. The result appears that intralesional excision with adjuvant therapy is feasible in the management of giant cell tumor of the acetabulum and is able to obtain a satisfactory outcome.

Acetabulum↗

PubMed2003

Isolation of multipotent mesenchymal stem cells from umbilical cord blood.

It is well accepted that umbilical cord blood has been a source for hematopoietic stem cells. However, controversy exists as to whether cord blood can serve as a source of mesenchymal stem cells, which can differentiate into cells of different connective tissue lineages such as bone, cartilage, and fat, and little success has been reported in the literature about the isolation of such cells from cord blood. Here we report a novel method to obtain single cell-derived, clonally expanded mesenchymal stem cells that are of multilineage differentiation potential by negative immunoselection and limiting dilution. The immunophenotype of these clonally expanded cells is consistent with that reported for bone marrow mesenchymal stem cells. Under appropriate induction conditions, these cells can differentiate into bone, cartilage, and fat. Surprisingly, these cells were also able to differentiate into neuroglial- and hepatocyte-like cells under appropriate induction conditions and, thus, these cells may be more than mesenchymal stem cells as evidenced by their ability to differentiate into cell types of all 3 germ layers. In conclusion, umbilical cord blood does contain mesenchymal stem cells and should not be regarded as medical waste. It can serve as an alternative source of mesenchymal stem cells to bone marrow.

Adipocytes↗

PubMed2003

Monteggia type I equivalent lesion: diaphyseal ulna and radius fractures with a posterior elbow dislocation in an adult.

BACKGROUND: A rare type I Monteggia equivalent lesion with a posterior dislocation associated with a diaphyseal radius and ulna fracture in an adult is described. The probable mechanisms of injury are speculated to include flexion of the elbow and pronation of the forearm. METHODS AND RESULTS: Early reduction of the dislocation and rigid fixation of the fractures helped to achieve excellent results.

Accidental Falls↗

PubMed2003

Computer-aided diagnosis for 3-dimensional breast ultrasonography.

HYPOTHESIS: Using 3-dimensional (3-D) over 2-dimensional (2-D) ultrasonographic (US) images of the breast represents a potentially significant advantage for computer-aided diagnosis (CAD). BACKGROUND: Although conventional 2-D US images of the breast are increasingly used in surgical clinical practice, 3-D US imaging of the breast, a newly introduced technique, can offer more information than 2-D US images do. DESIGN: This study deals with a CAD method for use with the proposed 3-D US images of the breast and compares its performance with conventional 2-D US versions. METHODS: The test databases included 3-D US images of 107 benign and 54 malignant breast tumors for a total of 161 US images. All solid nodules at US belong to categories above C3 (ie, probably benign). The 3-D US imaging was performed using a scanner (Voluson 530; Kretz Technik, Zipf, Austria). New 3-D autocorrelation coefficients extended from the traditional 2-D autocorrelations were developed to extract the texture characteristics of the 3-D US images. The extracted texture features of the 3-D US images were used to classify the tumor as benign or malignant using the neural network. RESULTS: At the receiver operating characteristic analysis, 3-D and 2-D autocorrelation calculating schemes yielded Az values (ie, area under the receiver operating characteristic curve) of 0.97 and 0.85 in distinguishing between benign and malignant lesions, respectively. Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value are statistically significantly improved using 3-D instead of 2-D US images for CAD. CONCLUSIONS: The proposed system (for 3-D and 2-D CAD) is expected to be a useful computer-aided diagnostic tool for classifying benign and malignant tumors on ultrasonograms and can provide a second reading to help reduce misdiagnosis. Findings from this study suggest that using 3-D over 2-D US images for CAD represents a potentially significant advantage.

Breast Neoplasms↗

PubMed2003

3-D US frame positioning using speckle decorrelation and image registration.

In this paper, a new positioning system is proposed for the 3-D ultrasound (US). This system combines the image registration technique and speckle decorrelation algorithm to accurately position sequential ultrasonic images without any additional positioning hardware. The speckle decorrelation algorithm estimates the relative distance of two neighboring frames and the image registration technique gets the range of the whole 3-D ultrasonic data set and makes slight modification on each frame's position. The image registration technique is based on the reference image, which is perpendicular to the 3-D ultrasonic data set. This reference image intersects each frame of the 3-D ultrasonic data set in a line. For each frame, the intersectional line is first found and then the location in the reference image can be used to estimate the position of this frame. This system uses the data set of consecutive 2-D freehand-scanned US B-mode images to construct the 3-D US volume data, and it can be integrated into the 3-D US volume rendering system.

Algorithms↗

PubMed2003

Breast cancer diagnosis using three-dimensional ultrasound and pixel relation analysis.

Because ultrasound (US) imaging offers benefits compared with other medical imaging techniques, it is used routinely in nearly all hospitals and many clinics. However, the surface features and internal structure of a tumor are not easily demonstrated simultaneously using the traditional 2-D US. The newly developed three-dimensional (3-D) US can capture the morphology of a breast tumor and overcome the limitations of the traditional 2-D US. This study deals with pixel relation analysis techniques for use with 3-D breast US images and compares its performance to 2-D versions of the images. The 3-D US imaging was performed using a Voluson 530 scanner. The rectangular subimages of the volume-of-interest (VOI) were manually selected and the selected VOIs were outlined to include the entire extent of the tumor margin. The databases in this study included 54 malignant and 161 benign tumors. All solid nodules at US belong over C3 (probably benign) according to ACR BI-RADS category. All or some selected 2-D slices were used separately to calculate the diagnosis features for a 3-D US data set. We have proposed and compared several different methods to extract the characteristics of these consecutive 2-D images. As shown in our experiments, the diagnostic results were better than those of the conventional 2-D US. In the experiments, the area index Az under ROC curve of the proposed 3-D US method can achieve 0.9700 +/- 0.0118, but Az of the 2-D US is only 0.8461 +/- 0.0315. The p value of these two Az differences using z test is smaller than 0.01. Furthermore, we can find that the features from only several slices are enough to provide good diagnostic results if the adopted features are modified from the 2-D features.

Breast Neoplasms↗

PubMed2003

Metal-backed patellar component failure in total knee arthroplasty presenting as a giant calf mass.

Failure of total knee arthroplasty (TKA) caused by wear of the polyethylene-bearing surface of a metal-backed tibial platform or a metal-backed patellar component is a recognized complication. We present a case of a 78-year-old woman with a cystic mass in the left calf caused by metal wear debris from the failure of a Miller-Galante I TKA. The patient received a left TKA to treat advanced osteoarthritis in July 1990 and was lost to follow-up immediately after the operation. In December 1998, she presented at our clinic 2 days before admission, when an originally silent mass over the calf turned intolerably painful. A series of examinations revealed a calf mass caused by wear debris of total knee prosthesis and subsequent inflammation of the knee joint. Curettage of the cyst and simultaneous revision TKA were successful in relieving her symptoms.

Aged↗

PubMed2003

Retrograde intramedullary Huckstep nailing for supracondylar fracture of femur after total knee arthroplasty.

Supracondylar fracture of femur after total knee arthroplasty (TKA) presents a challenge for orthopedic surgeons. It is controversial to treat such a fracture by using closed method or open method. Nonunion, malunion, knee rigidity and other complications in prolonged immobilization were noted in the closed method. Implant migration, infection, nonunion and malunion were also reported in open reduction treatment because of the difficulty to achieve rigid fixation. In this periprosthetic fracture, retrograde intramedullary Huckstep nailing provides a better chance to get rigid fixation compared with other fixation device, especially in osteopenic bone. We reported 2 cases with supracondylar fracture of femur after total knee arthroplasty that have been successfully treated with retrograde intramedullary nailing.

Aged↗

PubMedDate not supplied

Sonographically guided core needle biopsy of soft tissue neoplasms.

PURPOSE: This study was conducted to evaluate the usefulness of sonography (US)-guided needle biopsy in the diagnosis of soft tissue masses. PATIENTS AND METHODS: Thirty-seven patients with a mean age of 49 years were enrolled in the study. The size of the biopsy needle was selected according to the kind of tumor suspected (ie, primary or metastatic). In patients with suspected metastases, smaller biopsy needles were used; in patients with suspected primary tumors, larger needles were used so that larger specimens could be obtained. Prebiopsy color Doppler sonography (CDUS) was routinely used to guide the cutting needle to areas of the lesion showing sufficient vascularity. From 3 to 6 cores were obtained, depending on their quality. We compared the diagnoses yielded by the core biopsy and the final histopathologic analysis of the resected tumor by classifying the results as "concordant" or "discordant." RESULTS: A total of 37 tumors were examined. Final diagnoses were 24 malignant tumors (6 metastases and 18 primary tumors) and 13 benign tumors. The lesions were diagnosed correctly as either benign or malignant in 35 of the 36 cases for which needle biopsy specimens were adequate, with only 1 misdiagnosis. The diagnoses were concordant in 33 cases (17 primary malignant tumors, 6 metastatic tumors, and 10 benign tumors) and were discordant diagnosis in the other 4 cases (1 primary malignant tumor and 3 benign tumors). No complications were attributable to the needle biopsy. CONCLUSIONS: US-guided percutaneous core needle biopsy of soft tissue neoplasms is an easy, safe, and useful procedure. It can be considered a first-line procedure for the acquisition of tissue specimens adequate for histopathologic diagnosis.

Adolescent↗