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Biomedical subjects

J Greenleaf

Publications and source records attributed to J Greenleaf.

9 recordsLinked to original sources
PubMed2001

Neural network analysis of EUS images to differentiate between pancreatic malignancy and pancreatitis.

BACKGROUND: The differentiation of focal pancreatitis and pancreatic adenocarcinoma is problematic and often resolved only by pancreaticoduodenectomy. EUS is the most sensitive imaging modality for both conditions, yet ultrasonic criteria for distinguishing the two have not been described and differentiation remains difficult. The aims of this study were to develop a self-learning computer program that can analyze EUS images and differentiate malignancy from pancreatitis, and to compare results obtained with this system with EUS interpretation by experienced endosonographers. METHODS: Twenty-one patients with pancreatic cancer and 14 with focal pancreatitis were included. The diagnosis was confirmed histologically in all cases and each patient had undergone EUS. A single EUS image from each procedure was used for computer analysis. The results were compared with the EUS diagnosis reported at the actual procedure as well that of an endosonographer who reviewed videotapes of the procedures. RESULTS: The software program differentiated focal pancreatitis from malignancy with a maximal 89% accuracy. With sensitivity set at 100% for malignancy, the program was 50% specific and accuracy was 80%. Sensitivity and accuracy of the endosonographer's impression at the time of EUS were, respectively, 89% and 85%. A sensitivity of 73% and accuracy of 83% were achieved with blinded interpretation of EUS videotapes. CONCLUSIONS: Analysis of EUS images with computer software programs is feasible and compares favorably with human interpretation. The application of this technology to EUS and other imaging scenarios could be a useful adjunct to diagnostic endoscopy and warrants further investigation.

Adenocarcinoma↗
PubMed1992

Hawkins type III fracture-dislocation of the talus and diastasis of the tibiofibular joint without concomitant fracture of the malleolei. A case report.

A 23-year-old man injured his foot in a motorcycle accident. Roentgenograms and computed tomography scans demonstrated a Hawkins Type III fracture-dislocation of the talus with a suspected disruption of the anterior tibiofibular ligament. Prompt anatomic reduction of the talus with rigid internal fixation was performed. Intraoperative stress roentgenograms confirmed the presence of a syndesmotic disruption. No cases of this injury have been reported in the literature. When no obvious fracture of the ankle mortise is present in a Hawkins Type III or IV talar fracture-dislocation, care must be taken to fully evaluate the osseous and ligamentous structures of the ankle to rule out an occult injury. Computed tomography scans, stress roentgenograms, intraoperative clinical examination, and direct visual inspection can all be used to aid in this evaluation.

Adult↗
PubMed1990

Prosthetic materials for anterior cruciate ligament reconstruction.

Reconstruction of the anterior cruciate ligament (ACL)-deficient knee has been a major focus in sportsmedicine research over the past 20 years. The need for functional stability for patients with symptomatic instability, especially if they participate in pivoting or jumping sports, as well as the potential for development of precocious arthritis in the ACL-deficient knee, has led to the use of intra-articular autogenous reconstruction from multiple tissue sources. The most popular method of reconstruction involves the central one third of the patellar tendon with attached bone blocks from the patella and tibial tubercle; this remains the "gold standard" to which other reconstructions are compared. Other common tissue sources are the semi-tendinosus, gracilis, and fascia lata, utilized in a number of varied techniques. Although the initial strength of these various autografts has been more than adequate to withstand the stresses of various activities, autogenous tissue transplants undergo degeneration in a hostile synovial environment. Butler et al have shown that the original strength of patellar tendon grafts in primates declines approximately 15% within six weeks. The original strength sometimes fails to fully return, and there seems to be great variability in healing and revascularization of autogenous tissue. Furthermore, autogenous transplants require the sacrifice of a tendon or ligament with a biologic function. In other instances, autogenous tissue may not be available or easily sacrificed, most commonly secondary to a previous autogenous reconstruction that has failed. Over the last decade, there have consequently been extensive laboratory studies as well as clinical trials of various prosthetic materials.

Anterior Cruciate Ligament↗
PubMed1977

Digital image focussing in the near field of a sampled acoustic aperture.

A study has been carried out to investigate digital techniques which can be used to form fully focussed acoustic images. An algebraic approach was used rather than a Fourier technique. Pulse-echo data was digitized from a 2.4 cm long, 32 element, 3 MHz linear array. Water bath tests have demonstrated azimuthal resolution close to beig diffraction limited throughout the field of view. Good images of tissue samples in-vitro have been obtained. Consideration of image sampling requirements and symmetry properties have led to the development of an efficient processing algorithm.

Animals↗