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Biomedical subjects

W R Lees

Publications and source records attributed to W R Lees.

136 records · Page 8Linked to original sources
PubMed1978

The role of ultrasound scanning in the diagnosis of thyroid swellings.

This study has determined the ability of grey scale ultrasound to assess if a thyroid is normal or abnormal, if the appearances of the gland are specific for one disease and if the probability of malignancy can be determined. One hundred patients were studied, 65 with histologically confirmed diagnoses. It was found that the normal gland was distinguished from the abnormal with 99 per cent accuracy, simple cysts were diagnosed with 100 per cent accuracy and a specific disease diagnosis was given with 84 per cent accuracy. It was correctly stated in 87 patients that the disease was definitely benign, but in the remaining 12 patients (3 with cancer) it was stated that malignancy could not be excluded.

Cysts↗
PubMedDate not supplied

Radiofrequency ablation of colorectal liver metastases.

BACKGROUND: Untreated patients with colorectal liver metastases rarely survive 3 years, and the 3-year survival rate for patients treated with chemotherapy is 3%. The best survival rates are for the small subgroup that has operable disease, i.e., 39% at 5 years. Radiofrequency ablation (RFA) offers a new opportunity to destroy liver metastases in patients who are not surgical candidates because of disease distribution or comorbidity. METHODS: Acceptance criteria were a maximum of four or five liver lesions with a maximum diameter of 4 or 5 cm and no evidence of active extrahepatic disease. Nearly all treatments were performed percutaneously using ultrasound, computed tomography, or magnetic resonance imaging (or some combination) for guidance and monitoring. RFA is a minimally invasive procedure that can be readily repeated. General anesthesia facilitates the procedure but is not essential. Multiple overlapping ablations are required to ensure optimal treatment in all but the smallest tumors. RESULTS: In our cohort of 167 patients with colorectal liver metastases, 73 fulfilled the optimal acceptance criteria (5 or fewer tumors that were </=5 cm). The median survival periods were 38 months, with a 5-year survival rate of 30%, after the diagnosis of liver metastases and 31 months, with a 5-year survival rate of 25%, after the first ablation. CONCLUSION: RFA increases the therapeutic options for patients with colorectal metastases. Until controlled trials can better define the role of RFA, there are several groups of patients who are not surgical candidates and can be considered for RFA.

Adult↗
PubMedDate not supplied

CT mapping of the distribution of saline during radiofrequency ablation with perfusion electrodes.

PURPOSE: During radiofrequency (RF) ablation, adjunctive saline increases the size of the ablation zone and therefore electrodes that simultaneously deliver current and saline have been developed, but the addition of saline also results in an irregular ablation zone. Our aim was to study the distribution of saline during RF ablation. METHODS: Four patients were treated: 3 with liver metastases and 1 with hepatocellular carcinoma (HCC). Two different perfusion electrodes were used: a high-perfusion-rate, straight electrode (Berchtold, Germany) and a low-perfusion-rate, expandable electrode (RITA Medical Systems, USA). The saline perfusate was doped with non-ionic contrast medium to render it visible on CT and the electrical conductivity was measured. CT scans were obtained of each electrode position prior to ablation and repeated after ablation. Contrast-enhanced CT was performed 18-24 hr later to demonstrate the ablation zone. All treatments were carried out according to the manufacturer's recommended protocol. RESULTS: The addition of a small quantity of non-ionic contrast did not alter the electrical conductivity of the saline. Contrast-doped saline extravasated beyond the tumor in all 3 patients with metastases but was limited in the patient with HCC. In some areas where saline had extravasated there was reduced enhancement on contrast-enhanced CT consistent with tissue ablation. One patient treated with the high-perfusion-rate system sustained a jejunal perforation requiring surgery. CONCLUSION: Saline can extravasate beyond the tumor and with the high-perfusion-rate system this resulted in an undesirable extension of the ablation zone and a complication.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Non-optic endosonography in advanced carcinoma of the esophagus.

The assessment of advanced esophageal cancer with a 5-MHz steerable non-optic ultrasound probe is described. Non-optic endosonography was performed on 80 occasions in 50 patients; the probe could be passed successfully on 75 occasions. In all cases, good visualization of the extent of esophageal tumor was obtained and discrimination between the tumor mass and discrete peri-esophageal lymph nodes was possible. The technique was valuable in monitoring tumor response to laser therapy and radiotherapy, and in guiding the laser endoscopist away from areas of minimal thickening.

Adenocarcinoma↗
PubMedDate not supplied

Minimally invasive treatment of malignant hepatic tumors: at the threshold of a major breakthrough.

Six existing minimally invasive techniques for the treatment of primary and secondary malignant hepatic tumors--radio-frequency ablation, microwave ablation, laser ablation, cryoablation, ethanol ablation, and chemoembolization--are reviewed and debated by noted authorities from six institutions from around the world. All of the authors currently believe that surgery remains the treatment of choice for patients with resectable hepatic tumors. However, the clinical results of each of the minimally invasive techniques presented have exceeded those obtained with conventional chemotherapy or radiation therapy. Thus, for nonsurgical patients, these techniques are becoming standard independent or adjuvant therapies. In addition, with continued improvement in technology and increasing clinical experience, one or more of these minimally invasive techniques may soon challenge surgical resection as the treatment of choice for patients with limited hepatic tumor.

Antineoplastic Agents↗
PubMedDate not supplied

Three-dimensional imaging of the postmortem fetus by MRI: early experience.

OBJECTIVE: The feasibility and significance of three-dimensional (3D) visualization of the postmortem fetus using magnetic resonance imaging (MRI) was investigated. METHODS: 3D reconstruction of sectional MRI data sets from 8 postmortem fetuses was performed. RESULTS: Fetal configurations and internal structures, both normal and pathological, were clearly demonstrated by 3D display. CONCLUSION: This new technique provides high quality fetal 3D images for postmortem morphological diagnosis and interactive visual teaching. It may eventually have applications in prenatal diagnosis and the preoperative simulation of fetal surgery.

Anatomy, Cross-Sectional↗
PubMedDate not supplied

Three-dimensional magnetic resonance imaging of the postmortem fetal heart.

Five postmortem fetuses were scanned by magnetic resonance (MR) imaging. Of eight three-dimensional (3D) data sets reconstructed on an MGI workstation, five sets demonstrated detailed 3D fetal cardiac structures, and one depicted clear information regarding the disposition and compression of the heart and lungs in diaphragmatic hernia. This study has shown the potential of 3D MR imaging in support of postmortem examination and for interactive visual teaching of the fetal cardiac structures. The new technique may eventually be of significance in prenatal detection of cardiac abnormalities with the development of fast real-time MR imaging.

Aorta↗
PubMedDate not supplied

Preoperative ultrasound assessment of choledochal cysts. Report of three cases.

Ultrasonography performed with modern equipment is capable of outlining the anatomy of the biliary and pancreatic ducts within the head of the pancreas. We present two typical cases of choledochal cysts where ultrasound provided complete anatomic information and a more complicated case which required more extensive radiology.

Adult↗