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Biomedical subjects

W M Adams

Publications and source records attributed to W M Adams.

At least 19 recordsLinked to original sources
PubMed2000

Radiographic diagnosis of hip dysplasia in the young dog.

Despite considerable research and the application of screening programs during the past three decades, the incidence of canine hip dysplasia (CHD) remains disturbingly high. Mild CHD is underdiagnosed by subjective evaluation of adult dogs, and moderate CHD is underdiagnosed by subjective assessment of immature dogs. Coxofemoral subluxation measurement methods hold promise for increasing the accuracy of CHD assessment, especially in 4-month-old dogs. Many radiologists have greater confidence in the PennHip method than in subjective hip assessment alone for dogs 6 months of age or younger. The incidence of CHD is unlikely to be dramatically reduced until CHD registries are open to the public and CHD examination is required for purebred dog registration.

Age Factors↗
PubMed2000

The role of MR angiography in the pretreatment assessment of intracranial aneurysms: a comparative study.

BACKGROUND AND PURPOSE: With developments in coil technology, intracranial aneurysms are being treated increasingly by the endovascular route. Endovascular treatment of aneurysms requires an accurate depiction of the aneurysm neck and its relation to parent and branch vessels preoperatively. Our goal was to estimate the clinical efficacy of MR angiography (MRA) in the pretreatment assessment of ruptured and unruptured intracranial aneurysms. We compared MRA source data (axial acquired partitions), multiplanar reconstruction (MPR) of these data, as well as maximum intensity projection (MIP) and 3D-isosurface images with intraarterial digital subtraction angiography (IA-DSA). METHODS: The study was performed in 29 patients with 42 intracerebral aneurysms. The MRA data were examined in four different forms--as axial source data, MPR images of the source data, and MIP and 3D isosurface--rendered images. A composite standard of reference for each aneurysm was then constructed using this information together with the IA-DSA findings by looking at aneurysm detection rate, aneurysm morphology, neck interpretation, and branch vessel relationship to the aneurysm. All techniques, including conventional IA-DSA, were then scored independently on a five-point scale from 1 (non diagnostic) to 5 (excellent correlation with the standard of reference) for each of the aneurysm components as compared with the composite picture. An overall score for each technique was also obtained. RESULTS: Of the 42 aneurysms examined, 34 were small (<10 mm), six were large (10-25 mm), and two were giant (>25 mm). Three aneurysms were not detected with MRA. These were smaller than 3 mm and either in an anatomically difficult location (middle cerebral artery bifurcation) or obscured by adjacent hematoma. Two large aneurysms were depicted as undersized by IA-DSA owing to the presence of intramural thrombus shown by MRA axial source data. IA-DSA received the highest scores overall and in three of the four subgroups. Three-dimensional isosurface reconstructions scored higher than did IA-DSA for depiction of the aneurysm neck, although this difference was not significant. The MPR and 3D-isosurface images were comparable to those of IA-DSA in all categories. MPR images were particularly useful for defining branch vessels and the aneurysm neck. MIP images scored poorly in all subgroups (P < .005) compared with IA-DSA findings, except for in aneurysm detection. Source data images were significantly inferior to those of IA-DSA in all categories (P < .005). CONCLUSION: MRA is currently inferior to IA-DSA in pretreatment assessment of intracranial aneurysms, and can miss small lesions (<3 mm). It can, however, provide complementary information to IA-DSA, particularly in anatomically complex areas or in the presence of intramural thrombus. If MRA is used in aneurysm assessment, a meticulous technique with reference to both axial source data and MPR is mandatory. The axial source data should not be interpreted in isolation. Three-dimensional isosurface images are comparable to those of IA-DSA and are more reliable than are MIP images, which should be interpreted with caution.

Adult↗
PubMed1999

Familial tumoral calcinosis: association with cerebral and peripheral aneurysm formation.

Two siblings with histologically and radiologically proven tumoral calcinosis presented with cerebral and peripheral aneurysms. The brother died of a ruptured subclavian artery aneurysm after surgical repair of brachial, iliofemoral and coeliac axis aneurysms. Magnetic resonance and catheter angiography in the sister demonstrated marked carotid dysplasia and a left ophthalmic segment aneurysm, not amenable to treatment. We believe this is the first reported case of familial aneurysms in association with tumoral calcinosis.

Aneurysm↗
PubMed1999

Use of single-slice thick slab phase-contrast angiography for the diagnosis of dural venous sinus thrombosis.

The aim of this study was to examine the reliability of single-slice phase-contrast angiography (SSPCA) as a rapid technique for the investigation of suspected dural venous sinus occlusion. Images were obtained on 25 normal volunteers to document the accuracy of SSPCA in the demonstration of slow flow states. Normal volunteers were imaged using sagittal and coronal SSPCA (slice thickness 13 cm, matrix 256 x 256, TR 14 ms, TE 7 ms, flip angle 20 degrees, peak velocity encoding rate 30 cm/s). Sinus patency and flow rate were confirmed by measurement of flow in the superior sagittal and transverse sinuses using quantified single-slice phase difference images. Imaging was performed in 50 patients undergoing routine brain scans in order to determine the optimal slice orientation for clinical use. Twenty-one patients with suspected dural venous sinus thrombosis were also investigated with SSPCA and the diagnosis confirmed by one or more alternative imaging techniques. Imaging time was 29 s per acquisition and image quality was good in all cases. Variations in dural sinus patency and flow in normal volunteers were accurately predicted by SSPCA (kappa = 0.92). Use of a single angulated slice (130 mm thick, para-sagittal image angled 30 degrees towards coronal and 30 degrees towards transverse) provided sufficient separation of right- and left-sided venous structures to allow use of a single projection. The presence and extent of sinus occlusions in 14 patients and the absence of thrombosis in 7 were accurately identified by SSPCA. Sensitivity and specificity in this limited study were both 100%. The SSPCA technique takes less than 30 s and provides a reliable and rapid technique for the diagnosis of dural venous sinus thrombosis.

Adult↗
PubMed1998

US demonstration and diagnosis of the midaortic syndrome.

The midaortic syndrome is a rare entity, typically presenting with hypertension, refractory to treatment. The diagnosis is usually made by arteriography. We report a child in whom the diagnosis was made by ultrasound, confirmed by arteriography and successfully treated by balloon dilatation.

Adolescent↗
PubMed1998

Pneumosinus dilatans: a discussion of four cases and the possible aetiology.

Pneumosinus dilatans is an abnormal dilatation of the paranasal sinuses, which contains only air and is lined by normal mucosa. It is a rare condition, the aetiology of which is unclear. We describe four patients who presented to our department with pneumosinus dilatans. The aetiology was either developmental hydrocephalus (n = 1), post-traumatic (n = 1) or idiopathic (n = 2). Two patients underwent surgery, and follow-up is at least 12 months to date. The radiological aspects of this rare condition and the possible aetiologies are discussed.

Adolescent↗
PubMed1997

Temporary balloon occlusion of the inferior vena cava as an alternative to cardiopulmonary bypass in resection of Wilms' tumour with vena cava extension.

Up to 10% of patients undergoing nephrectomy for Wilms' tumour have tumour thrombus involving the vena cava. A new radiological technique is described utilising a temporary occlusion balloon inserted via an open venotomy of the left internal jugular vein into the retro-hepatic cava to create a bloodless field to facilitate surgery.

Cardiopulmonary Bypass↗
PubMed1997

CT assessment of jugular foramen dominance and its association with hand preference.

Three hundred and seven normal CT scans of the head were prospectively analysed to assess jugular foramen dominance. After assessment, hand preference was elicited. Of these, 276 were right-handed and 31 were left-handed. Of the right-handed patients: 180 had a larger jugular foramen on the right; 63 had a larger jugular foramen on the left; and in 33 no difference could be discerned. Of the left-handed patients: 11 had a larger jugular foramen on the right; 16 had a larger jugular foramen on the left; and in four no difference could be discerned. The results suggested a significant association between jugular foramen dominance and hand preference.

Chi-Square Distribution↗
PubMed1997

Dysbaric osteonecrosis in divers and caisson workers. An animal model.

Dysbaric osteonecrosis was induced successfully in adult sheep after 12 to 13, 24-hour exposures to compressed air (2.6-2.9 atmospheres absolute) during a 2-month period. All exposed sheep had decompression sickness and extensive bone and marrow necrosis in their long bones. Radiographic analysis of these progressive lesions showed mottled to distinct medullary opacities and endosteal thickening characteristic of dysbaric osteonecrosis. Six months after the last hyperbaric exposure, neovascularization of once ischemic fatty marrow was centripetal from the diaphyseal cortex. Proliferating endosteal new bone, fatty marrow calcification, and appositional new bone formation were widespread. Juxtaarticular osteonecrosis involved marrow fibrosis and loss of osteocytes in subchondral cortical bone. Tidemark reduplication in juxtaarticular bone and cartilage thinning suggested possible early osteoarthritis induction by recurrent episodes of transient ischemia after multiple hyperbaric exposures. Dysbaric osteonecrosis appears to involve a bone compartment syndrome of elevated intramedullary pressure initiated by decompression induced N2 bubble formation in the fatty marrow of the long bones. An animal model that can be used to investigate the pathogenesis, diagnosis, and treatment of dysbaric osteonecrosis is discussed.

Animals↗
PubMed1988

Thermal dosimetry of normal porcine tissue.

The response of normal porcine fat and muscle to graduated doses of hyperthermia provided by an annularly focused acoustic source was measured. Temperatures and exposure times were varied between 43 degrees C (20-90 min), 45 and 47 degrees C (20-60 min), and 49 degrees C (20 min). Response, based on histologic grading of the treated sites 30 days after exposure, was found to correlate well when mapped against several methods of estimating thermal energy deposition. The threshold for damage production was at or near 43 degrees C. For a given temperature, a nearly exponential increase in relative tissue damage as a function of increased exposure time was found. A twofold increase in tissue damage was produced in fat relative to muscle at any given thermal dose.

Adipose Tissue↗
PubMed1987

Radiotherapy of malignant nasal tumors in 67 dogs.

The nasal cavity of 67 dogs with malignant nasal neoplasia was treated with radiation. Preirradiation surgical cytoreduction of the tumor was done in 41 dogs. Fifty dogs were irradiated by use of 10 fractions over 22 days, and 17 dogs were given a similar total dose in 5 fractions over 35 days. The range of survival times (0.5 to 42 months), median survival time (8.5 months), and 1- and 2-year survival rates (38% and 30%, respectively) were better than those expected for other methods of treatment. Serious complications were few (4%). Survival times for dogs were determined on the basis of histologic tumor type and on the basis of megavoltage (cobalt or linear accelerator) vs softer deep radiation (cesium or orthovoltage) treatment, with or without cytoreductive surgery. Survival times of 10 dogs given softer radiation without surgery were shorter than those of 14 dogs that were given softer radiation and had cytoreductive surgery. Survival times of dogs that were given softer radiation and had surgery were similar to those of dogs that were given megavoltage radiation only. Cytoreductive surgery did not improve survival times for dogs that were given megavoltage radiation. Median survival time for 38 dogs with adenocarcinoma was 12 months, compared with 6 months for 14 dogs with squamous cell or undifferentiated carcinoma. Median survival time for 16 dogs with a variety of sarcomas was 11.2 months. Survival times of dogs with adenocarcinoma or sarcoma were significantly better (P less than 0.02 or 0.03) than for dogs with squamous cell or undifferentiated carcinoma. Necropsies were performed on 27 of 58 dogs that died or were euthanatized.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗