Development of the UK food samples surveillance system.

OBJECTIVES: To describe the UK Food Surveillance System (FSS UK) currently in operation in Scotland and Northern Ireland, and being introduced UK-wide, particularly in relation to the development, scope and roll-out of the system. STUDY DESIGN: Pilot questionnaire, followed by pilot information technology (IT)-based study and subsequent roll-out. METHODS: A paper-based trial of data collection was introduced, followed by an IT-based pilot and the subsequent development of an IT-based system and an Internet-based resource. A project working group and specific user groups were formed to assist the dedicated project team to progress the project. The groups' compositions reflect the interests of the various partner organizations, including the involvement of the Food Standards Agency. RESULTS: Following the successful pilot study, Health Protection Scotland was commissioned by the Food Standards Agency to develop and roll-out FSS UK to councils and their partner laboratories throughout the UK within a 3-year period. CONCLUSION: The development of FSS UK provides the opportunity to compare and contrast national food sample data, highlight emerging food-related trends and provide an early warning system for food-related issues.

Indicator dilution measurements of lung volumes and alveolar air exchange during breathing.

A new triple tracer indicator dilution technique has been used to measure alveolar ventilation as well as air and tissue volumes in the lungs of experimental animals and man. The tracers indocyanine green, [(121)I]antipyrine and xenon-133 were rapidly injected into the right atrium, while sampling was carried out from a peripheral artery. Blood flow and tissue volumes were obtained by classical analysis of the indocyanine green and antipyrine concentration-time curves. A double exit-port, constant air flow model was used to analyze the xenon curves, because ventilatory loss led to incomplete recovery of the gas tracer in effluent blood. Uniform ventilation and perfusion were assumed. This analysis permitted calculation of alveolar ventilation (VA(Xe)) and functional residual capacity (FRC(Xe)) during normal breathing. In control studies, VA(Xe) was similar to VA(co2), obtained with the steady-state CO(2) method (r = 0.87), while in critically ill patients the xenon measurement was significantly lower, averaging 54% of VA(co2). In theory, underestimates in VA(Xe) and decrease in the ratio VA(Xe)/VA(co2) relate to nonuniformity in regional ventilation and perfusion. The effect is greatest for the slightly soluble gas, xenon. The significant inverse correlation between VA(Xe)/VA(co2) and the physiologic shunt is consistent with this postulate.FRC(Xe) was similar to the predicted FRC in animals but was 76% of the helium measured FRC in patients. FRC(Xe) was significantly lower than the xenon measured air volumes during breath-holding when nonuniformity of ventilation was not operative. Lung tissue volumes in animals were 83% of gravimetric lung weights, while in patients the volumes were much lower than predicted. Nonhomogeneous lung function, including failure to perfuse the entire capillary bed, with resultant incomplete penetration of tracers into all segments of lung air and tissue, may explain these findings. The resultant errors can be significant in sick patients, and may themselves be used to study nonhomogeneities in the distribution of ventilation and volume.

A new tumor model for angiographic investigations: feline sarcoma virus tumor induction in adult cats.

This article describes the first successful virus induction of sarcomas in adult immunosuppressed cats. The method of tumor induction, the immunosuppression regimen, and the gross, histologic, and angiographic findings in these induced sarcomas are described. The simplicity of the model, the rapid and reliable growth of the tumors, and the size of the animals permit repeated angiography. The model is well suited to studies of angiographically directed therapy with embolic agents, radioactive implants, or chemotherapeutic drugs. The use of a feline model permits repeated selective angiography, which is not the case with small laboratory animals, in which such studies are difficult. In this investigation, tumors were induced into the right hepatic lobe because of the relative homogeneity of peripheral hepatic vascularity and the ease with which early neoplastic changes can be detected. There is good evidence to indicate that virus induction sites in other organs would also be successful.

Noninvasive blood flow measurements by Doppler ultrasound with application to renal artery flow determination.

A description of a new Doppler ultrasound flow measuring instrument is given along with representative measurements of blood flow in the canine renal artery and the human aortic arch, renal artery, and transplanted kidney renal artery. The instrument is briefly described, and a discussion of the limitations of the technique is presented.

New videodensitometric method for measuring renal artery blood flow at routine arteriography: validation in the canine model.

A contrast medium was injected in the aortic arch and selectively in a renal artery to estimate the renal blood flow as a percentage of the cardiac output by the videodensitometric (VD) method. Twenty-six paired VD measurements in four mongrel dogs were obtained and the results compared to electromagnetic (EM) flow readings from the aortic arch and a renal artery. The relative renal blood flow estimated by the VD method averaged 9.1% and correlated with the EM flow average of 9.6% with r = 0.96. Previous in vitro investigations of relative flow in a model have now been validated in vivo. These results suggest that videodensitometry could be a clinical tool for measuring renal blood flow in conjunction with routine arteriography.

Quantitative stereology and radiologic image analysis. Part I: Computerized tomography and ultrasound.

The interpretation of two-dimensional radiographs or computerized tomography (CT) or ultrasound (US) sections with inferences made about three-dimensional anatomy is the foundation of diagnostic radiology. A large variety of estimation methods which can be applied to two-dimensional CT/US sections to estimate their three-dimensional properties is presented. The techniques are easily utilized in a research or clinical setting, do not require computerization, and can provide statistically accurate three-dimensional information based on two-dimensional sampling with a minimum of effort. Although the examples are directed at diagnostic radiology, the estimation procedures may be employed in analogous fields such as microscopy or section anatomy.

Magnetic resonance imaging of the brain in dogs with recently diagnosed but untreated pituitary-dependent hyperadrenocorticism.

Magnetic resonance imaging was used to determine the prevalence of visible pituitary masses in 21 dogs with recently diagnosed and untreated pituitary-dependent hyperadrenocorticism. All dogs had clinical signs and routine database values (CBC, serum biochemical panel, and urinalysis) consistent with a diagnosis of hyperadrenocorticism, and none had clinical signs suggestive of an intracranial mass. Each dog had plasma cortisol concentrations after adrenocorticotropic hormone administration or low-dose dexamethasone administration consistent with hyperadrenocorticism. Pituitary-dependent hyperadrenocorticism was confirmed by the finding of 2 equal-size adrenal glands on abdominal ultrasonography and by results of plasma endogenous adrenocorticotropic hormone concentration and high-dose dexamethasone suppression testing. Sagittal and transverse T1-weighted magnetic resonance images of the brain were obtained before and after IV administration of gadopentenate dimeglumine. Eleven dogs had visible masses, ranging in size from 4 to 12 mm at greatest vertical height. Mean age and body weight of dogs with a visible pituitary mass was not significantly different from dogs without a visible mass. There was no significant difference in endocrine test results when comparing dogs with a visible pituitary mass to dogs without. The prevalence of visible pituitary masses in dogs with pituitary-dependent hyperadrenocorticism was greater than suggested by the prevalence of clinical neurologic signs.

Magnetic resonance imaging for diagnosis of pituitary macrotumors in dogs.

The value of magnetic resonance imaging (MRI) for the evaluation of dogs with pituitary-dependent hyperadrenocorticism (PDH) and CNS signs was assessed. Magnetic resonance imaging of the brain was performed in 13 dogs with PDH and neurologic signs. The diagnosis of PDH was made on the basis of results of adrenocortical function tests and abdominal ultrasonography, in conjunction with appropriate history, clinical signs, and clinicopathologic alterations. Eight dogs had been treated with the adrenocorticolytic agent, mitotane, for 1 to 30 months before the development of neurologic signs. Prior to MRI, each dog had progressive neurologic signs that could not be attributed to hypocortisolism or mitotane toxicosis. The neurologic signs most frequently detected were disorientation and ataxia. Mean age of dogs at the time neurologic signs developed was 9.5 years. Sex predilection was not detected; however, most were large-breed dogs, with 11 of the 13 dogs weighing more than 20 kg. A large mass in the pituitary gland, suprasellar region, or both was easily identified on the magnetic resonance images of each dog. The masses ranged from 8 to 24 mm in size. Expansion of tumors into the suprasellar region and compression of structures adjacent to the pituitary gland were readily detected by MRI. Contrast enhancement did not improve tumor identification, but did enable better delineation between tumor and surrounding structures. After the diagnosis of a macrotumor was made by MRI, radiotherapy was initiated in 9 dogs and was successfully completed in 6. Three dogs had a relapse of neurologic signs 8, 11, and 26 months after radiotherapy was completed.(ABSTRACT TRUNCATED AT 250 WORDS)

One-year follow-up evaluation of magnetic resonance imaging of the brain in dogs with pituitary-dependent hyperadrenocorticism.

OBJECTIVE: To evaluate magnetic resonance imaging (MRI) brain scans of dogs with pituitary-dependent hyperadrenocorticism (PDH) and no signs of CNS dysfunction 1 year after diagnosis and initial MRI. DESIGN: Prospective study of surviving dogs from a previous study. ANIMALS: 13 dogs underwent MRI of the brain at the time that PDH was diagnosed and prior to treatment. At that time, none of the dogs had clinical signs suggestive of an intracranial mass. Approximately 1 year after diagnosis and MRI, the brain was again evaluated by MRI. RESULTS: On the initial MRI scan, 5 of the 13 dogs had normal findings, and 8 had evidence of a mass (tumor) in the area of the pituitary gland. Of the 5 dogs that had no visible pituitary mass on the initial MRI scan, 3 had a normal MRI brain scan 1 year later. Of the 5 dogs that had no visible pituitary mass on initial MRI scan, 2 had a visible pituitary mass at 1 year. The 8 dogs that had a visible mass on the initial MRI brain scan had easily identified pituitary masses on the second MRI scan. Of these 8 dogs, 4 had no apparent change in pituitary mass size, and 4 had obvious increase in vertical height of the pituitary mass. Of the 4 dogs, 2 developed signs of neurologic dysfunction within 1 year after diagnosis of PDH, presumably attributable to that mass. Of the 13 dogs, 12 were treated with mitotane soon after completion of the initial MRI scan. Sensitivity to mitotane and initial pituitary mass size or growth were not correlated. Of the 13 dogs evaluated initially and 1 year after diagnosis, 10 had pituitary masses identified on MRI brain scans. CLINICAL IMPLICATIONS: The incidence of visible pituitary masses among dogs with PDH at the time of or within a year of diagnosis was > 75%. In 2 dogs, signs of CNS dysfunction developed within 1 year of PDH diagnosis when pituitary masses were > or = 10 mm.

Mammography- misunderstood and underutilized.

A mammography screening program for breast cancer carried out in Sacramento by the University of California Davis School of Medicine, Davis, was canceled because of negative public reaction to sensationalized reports in the lay press on the potential carcinogenic risks of the radiation exposure, along with passivity on the part of the medical community in defending the procedure and the program. Disappointment in this occurrence spurred us to explore physician's knowledge of and attitudes toward breast cancer and mammography. The results confirmed our suspicions that a significant number of physicians lack accurate knowledge of breast cancer and of the extremely high benefit-to-risk ratio of mammography as a means of early detection.

Laryngeal carcinoma: high-resolution computed tomography and thick anatomic sections.

High-resolution 2-mm thick sequential CT scans of 23 patients with primary laryngeal carcinoma were reviewed to judge the value of CT in early tumor detection and the ability of CT to establish tumor extent reliably, particularly early cartilage invasion. False-negative results were likely when superficial lesions were confined to the true vocal cord mucosa. False-positive examinations occurred with vocal cord polyps and with acute and chronic granulomatous reaction of the vocal cords. In tumors large enough to be imaged, there were no false negatives. False-positive results for clearly identified tumors were related to the interpretation of tumor on CT where only edema was present at surgery. Both early and gross cartilage invasion were well correlated with surgically resected specimen sections. Early cartilage involvement by tumor can be detected by the development of a fenestrated chondral margin. Other benign expansive cartilage processes, such as occur with chondromas, have calcified cartilage fragment distributions that are out of proportion to any soft-tissue mass present.

Improved ultrasound image detail using wide aperture, focused transducers.

Image resolution of anatomic parts located 3--4 cm below the skin surface can be improved with current digital B-scanners and a large aperture, high frequency, focused transducer. Such a transducer that has a very sharp focus over a limited depth of focus is described. The width of the field of view is unlimited, and image detail approaches that obtained with specialized real time scanners, although performance of the examination may not be as convenient or rapid. Examples of improved resolution are given for the thyroid, carotid artery, infant pancreas, ovary, and placenta.

Visualization of the bile ducts using focused ultrasound.

The feasibility of using focused ultrasound for studying structures as small as biliary ducts and correlative radiological and ultrasonic studies of the common and larger hepatic ducts are presented. Patients whose bile ducts were visualized on intravenous or T-tube cholangiography or oral cholecystography underwent radiography with a metallic skin marker along the right anterior lower costal margin. The marker was then correlated with ultrasonic observations of multiple oblique scans parallel to the lower costal margin. The common duct could be identified in 15 of 21 patients. Ultrasonic visualization circumvents the problems of elevated serum bilirubin, iodine contrast media sensitivity, and pregnancy.

Organ and lesion volume measurements with computed tomography.

Useful clinical information will often result from determinations of organ and lesion tissue volumes from measurements of computed tomographic (CT) cross sections. This paper discusses simple applications of stereology to volume estimations of organs and disease processes. The method is applied to CT sections and, for equivalent accuracy, is less time consuming than planimeter or CT scanner region of interest outlining and measurements.

Outpatient low-dose computed tomography metrizamide myelography and evaluation of lumbar disk disease.

Outpatient low-dose computed tomography metrizamide myelography (CTMM) for the evaluation of lumbar disk disease is described in 55 patients. Ten individuals (group 1) were studied using 3.5 ml of 150 mg I/ml (525 mg I total) of metrizamide. Forty-five additional patients (group 2) were examined with 5 ml of 110 mg I/ml (550 mg I total) concentration of metrizamide. Group 2 experienced less post-procedure headache (6.6%) and nausea (2.2%) than did group 1 (30% and 10%, respectively). Group 2 demonstrated a lowered rate of headache (p less than .01) and showed a trend to less nausea (p less than .09) than a recently published study describing full-dose lumbar myelography. In addition, CTMM in group 2 produced more uniform mixing of metrizamide than in group 1. Overall, low-dose CTMM increased accuracy and reduced morbidity, patient cost, and inconvenience as compared with routine full-dose lumbar myelography.

Statistical detection of nonvisible isodense subdural fluid collections.

An analytic method for detecting isodense subdural fluid collections from computed tomography (CT) scan pixel attenuation data is presented. Analysis of 44 CT scan levels from 8 patients with isodense subdural hematomas (ISDH) and 50 CT scan levels from 15 patients without ISDH indicates 6% false positive and 3% false negative errors if the analysis is restricted to noncontrast CT scans that demonstrate subcalvarial bilateral cortical attenuation symmetry in the pictorial display.

Design for an ultrasound-based instrument for measurement of tissue blood flow.

Quantitative measurement of tissue blood flow is of importance for many reasons: detection of capillary flow disturbances, evaluating indications for amputation, investigating vasospastic conditions, and evaluating vasoactive drugs or the effect of sympathectomy. Methods of investigating tissue blood flows include skin thermometry, thermal conductance or clearance, transcutaneous PO2, laser doppler flux, and photoplethysmographic techniques. A major reason that ultrasound has not previously been applied to this problem is that at the very low blood velocities in the capillaries (0.1 to 1 mm/sec) the Doppler shift is small (on the order of 1 Hz/MHz of carrier signal). Advantages of ultrasound are a noninvasive procedure and penetration depths greater than that possible with optical techniques. This paper discusses the development of a Doppler ultrasound instrument which allows spectral resolution of the velocities in tissue blood flow. Briefly, a low phase noise oscillator at 7.5 Mhz is used with two transducers to obtain the shifted signal. After mixing with the fundamental, the resulting low frequency signal is fed into a high resolution spectrum analyzer for analysis.