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J G Murray

Publications and source records attributed to J G Murray.

At least 19 recordsLinked to original sources
PubMed2006

Diagnosis of pulmonary emboli and image quality at CT pulmonary angiography: influence of imaging direction with multidetector CT.

AIM: To determine whether there was a significant difference in the prevalence of emboli detected when patients underwent computed tomography pulmonary angiography (CTPA) in a craniocaudal direction versus a caudocranial direction. MATERIALS AND METHODS: This was a prospective study of 203 consecutive patients attending for CTPA for suspected pulmonary embolus. Imaging was performed on a multisection Siemens Volume Zoom CT machine, with bolus tracking centred on the main pulmonary artery after intravenous administration of contrast at 3 ml/s. Patients were examined in a single breath-hold, from the top of the aortic arch to the highest point of the diaphragm, in a randomly assigned cranio-caudal (group A), or caudo-cranial (group B) direction. Images were reviewed on a workstation in a cranio-caudal direction jointly by two radiologists unaware of the original imaging direction. The presence, number and position of arterial emboli were noted, and a subjective assessment of overall image quality and opacification of upper and lower lobe vessels (grade 1, 2, 3, or 4) was made. RESULTS: Emboli were detected in 46 patients. There was no significant difference in the prevalence of emboli detected in the two groups [group A craniocaudal direction n=22, group B caudocranial direction n=24 (p=0.76)]. Imaging direction did not significantly influence overall image quality (p=0.07), however, there was a significantly greater proportion of patients in group A with grade 1 opacification of the upper lobe arteries (p=0.02). CONCLUSION: Imaging direction does not significantly influence the diagnosis of pulmonary emboli but it does significantly improve the upper lobe pulmonary arterial enhancement with fewer non-diagnostic images, and on that basis we recommend that craniocaudal direction be used for CTPA studies.

Adolescent↗
PubMed2006

Meeting the requirements of importing countries: practice and policy for on-farm approaches to food safety.

In light of the increasing consumer demand for safe, high-quality food and recent public health concerns about food-borne illness, governments and agricultural industries are under pressure to provide comprehensive food safety policies and programmes consistent with international best practice. Countries that export food commodities derived from livestock must meet both the requirements of the importing country and domestic standards. It is internationally accepted that end-product quality control, and similar methods aimed at ensuring food safety, cannot adequately ensure the safety of the final product. To achieve an acceptable level of food safety, governments and the agricultural industry must work collaboratively to provide quality assurance systems, based on sound risk management principles, throughout the food supply chain. Quality assurance systems on livestock farms, as in other parts of the food supply chain, should address food safety using hazard analysis critical control point principles. These systems should target areas including biosecurity, disease monitoring and reporting, feedstuff safety, the safe use of agricultural and veterinary chemicals, the control of potential food-borne pathogens and traceability. They should also be supported by accredited training programmes, which award certification on completion, and auditing programmes to ensure that both local and internationally recognised guidelines and standards continue to be met. This paper discusses the development of policies for on-farm food safety measures and their practical implementation in the context of quality assurance programmes, using the Australian beef industry as a case study.

Animal Husbandry↗
PubMed2004

Risk of pulmonary embolism after negative MDCT pulmonary angiography findings.

OBJECTIVE: The purpose of our study was to determine the risk of pulmonary embolism in patients who have negative MDCT pulmonary angiography findings. SUBJECTS AND METHODS: In this prospective study, one hundred two consecutive patients with suspected pulmonary embolism underwent MDCT pulmonary angiography. Scans were reviewed jointly by two observers and findings recorded by consensus. Observers noted whether pulmonary embolism or other disease was present. No pulmonary embolism was seen in 85 patients (52 men and 33 women; age range, 20-94 years; mean age, 60 years) who were followed up for a mean of 9 months (range, 4-13 months) for evidence of subsequent pulmonary embolism. RESULTS: One patient had a diagnosis of pulmonary embolism made within 3 weeks of undergoing CT pulmonary angiography. MDCT pulmonary angiography showed additional potentially significant findings in 76% of patients; 47% of these findings were not suspected on chest radiography. CONCLUSION: The risk of pulmonary embolism at a mean of 9 months after negative MDCT pulmonary angiography findings is 1%. In our study of patients without pulmonary embolism, MDCT pulmonary angiography revealed other causes for individual patients' signs or symptoms in most cases.

Adolescent↗
PubMed2003

Quality assurance and meat inspection in Australia.

The aim of meat inspection in Australia is to contribute to the production of safe and wholesome food, comply with the requirements of importing countries, and support national animal health objectives. An analysis of the role of quality assurance (QA) in the meat inspection systems at federally inspected establishments shows that the position of Australia as a leading meat exporter is aided by a co-regulatory, QA-based approach to meat inspection, which is equally applicable to all species at slaughter. Technical developments in meat inspection at the national and international level during the 1990s led to significant enhancements in QA systems. Quality assurance is implemented through nationally uniform documented systems, which are designed to achieve consistent standards of meat safety. These systems are complemented by hazard analysis critical control point-based QA programmes which meet the quality-standards of the International Organization for Standardization. Quality assurance programmes aim for a 'whole of chain' approach, so that the system is implemented 'from the paddock to the plate', or from pre-harvest through to post-harvest, i.e., from on-farm practices to the refrigeration, storage and transportation stages. The QA elements of meat inspection employed in production systems in Australia have significantly contributed to the consistent achievement of meat safety objectives that are appropriate to contemporary risks.

Animal Husbandry↗
PubMed2002

Direct modulation of the effective sensitivity of a CCD detector: a new approach to time-resolved fluorescence imaging.

In this paper a novel approach to frequency-domain fluorescence lifetime imaging (FLIM) is described. In a CCD camera a single pixel is defined by a charge pattern on a group of electrodes. By modulation of the pattern of voltages defining the pixel structure it is possible to modulate the sensitivity of the CCD at radio frequency. The modulation enhances the noise performance of the CCD, in contrast to the deterioration in performance seen when an intensifier stage is similarly modulated. The new technology has potential applications to a wide range of assays as well as in conventional FLIM applications. Unlike intensifier-based systems, the directly modulated CCD is physically small, inexpensive, robust and offers superior resolution and noise performance.

Journal Article↗
PubMed2002

Measurement of nanosecond time-resolved fluorescence with a directly gated interline CCD camera.

CCD cameras coupled optically to gated image intensifiers have been used for fast time-resolved measurements for some years. Image intensifiers have disadvantages, however, and for some applications it would be better if the image sensor could be gated directly at high speed. Control of the 'charge drain' function on an interline-transfer CCD allows the sensor to be switched rapidly from an insensitive state. The temporal and spatial properties of the charge drain are explored in the present paper and it is shown that nanosecond time resolution with acceptable spatial uniformity can be achieved for a small commercial sensor. A fluorescence lifetime imaging system is demonstrated, based on a repetitively pulsed laser excitation source synchronized to the CCD control circuitry via a programmable delay unit.

Journal Article↗
PubMed2002

Economic aspects of foot and mouth disease: perspectives of a free country, Australia.

Australia is a significant livestock producer and a major exporter of livestock, livestock products and livestock genetic material. An outbreak of foot and mouth disease (FMD) would have severe economic consequences on the economy. A recent study found that in an outbreak lasting six months, real gross domestic product in Australia would fall by an estimated 0.6% (AUS$3.5 billion), employment by 0.8%, and a depreciation of 3% would be recorded in the exchange rate in the first year. Much of this impact would be due to the loss of export markets. Given the significant consequences of an outbreak of FMD, Australia invests considerable resources in prevention and planning. These measures can be viewed at three levels, namely: pre-border, border and post-border. Australia recently further enhanced quarantine at the border to minimise the risk of entry of FMD. However, no matter how much is invested, there is no guarantee that FMD will not enter the country. Accordingly, it is important to ensure that comprehensive contingency plans are also in place. Recent outbreaks in previously free countries have shown that a large outbreak of FMD poses major problems for the animal health services of a country and a combined government and industry response is required.

Animal Husbandry↗
PubMed2001

Liver biopsy.

Explore the source record for details and available documents.

Biopsy↗
PubMed2001

Value of subtraction technique in Gd-DTPA-enhanced magnetic resonance angiography of the thoracic aorta.

AIM: To assess routine image subtraction in 3D gadopentate dimeglumine (Gd-DTPA)-enhanced magnetic resonance (MR) angiography of the thoracic aorta. MATERIALS AND METHODS: This was a prospective study of 22 consecutive patients referred for magnetic resonance imaging (MRI) of the thoracic aorta. All patients had 3D MR aortography (TR/TE/FA; 5/2 ms/25 degrees ) performed before and after bolus intravenous injection of Gd-DTPA. The Gd-DTPA enhanced and unenhanced data sets were subtracted and maximum intensity projections (MIP) projections of the thoracic aorta were performed. The standard unsubtracted MIP images were initially evaluated. These were then reviewed together with the subtracted images to assess for additional diagnostic information. Signal to noise ratios (SNR) and contrast to noise ratios (CNR) were measured. RESULTS: In four cases there was mild image degradation due to patient movement. In no case did subtraction alter the diagnosis. The mean SNR in the unsubtracted MIP images was 10.8 +/- 4.0 (median 11.1) and on the subtracted images was 21.2 +/- 9.9 (median 20.7;P < 0.0001). The mean aorta-to-mediastinal fat CNR was 3.9 +/- 2.8 (median 3.9) on the unsubtracted images and 15.0 +/- 10.6 (median 13) on the subtracted images (P < 0.0001). The mean aorta-to-vertebral body CNR was 5.2 +/- 3.1 (median 4.4) on the unsubtracted images and 15.1 +/- 9.3 on the subtracted images (P < 0.0001). CONCLUSION: Image subtraction significantly improved both the SNR and CNR, but did not alter the final diagnosis, and does not appear warranted in routine practice.

Adolescent↗
PubMed2001

The "dependent viscera" sign in CT diagnosis of blunt traumatic diaphragmatic rupture.

OBJECTIVE: The objective of our study was to describe the "dependent viscera" sign and determine its usefulness at CT in the diagnosis of diaphragmatic rupture after blunt abdominal trauma. MATERIALS AND METHODS: The study sample consisted of 28 consecutive patients (19 men, nine women) between 17 and 74 years old (mean age, 31 years) who had undergone abdominal CT and subsequent emergency laparotomy after a blunt trauma. Ten patients had a diaphragmatic rupture (six, right-sided; four, left-sided) at laparotomy. An experienced radiologist unaware of the surgical findings retrospectively reviewed the CT scans, and then a second radiologist reviewed the scans to provide interobserver agreement. Note was made of discontinuity of the diaphragm, intrathoracic herniation of abdominal contents, and waistlike constriction of bowel (the collar sign). Also noted was whether the upper one third of the liver abutted the posterior right ribs or whether the bowel or stomach lay in contact with the posterior left ribs. Either of these findings was termed the "dependent viscera" sign. The radiologists' detection rate of diaphragmatic rupture on the CT scans via observance of the dependent viscera sign was determined. Interobserver agreement was assessed using Cohen's kappa statistic. RESULTS: The dependent viscera sign was observed on the CT scans of 100% of the patients with a left-sided diaphragmatic rupture and of 83% of the patients with right-sided diaphragmatic rupture. Both observers missed one case of right-sided diaphragmatic rupture. The radiologists' overall rate of detecting diaphragmatic rupture was 90% using the dependent viscera sign. We found excellent interobserver agreement (kappa = 1) for detection of the dependent viscera sign and for the diagnosis of diaphragmatic tear on CT scans. CONCLUSION: The dependent viscera sign increases the detection at CT of acute diaphragmatic rupture after blunt trauma.

Adolescent↗
PubMed2000

Giant distal humeral geode.

We describe the imaging features of a giant geode of the distal humerus in a patient with rheumatoid arthritis, which presented initially as a pathological fracture. The value of magnetic resonance imaging in establishing this diagnosis is emphasized.

Arthritis, Rheumatoid↗
PubMed2000

MR cholangiopancreatography of pancreaticobiliary diseases: comparison of single-shot RARE and multislice HASTE sequences.

AIMS: We prospectively compared two breath-hold magnetic resonance cholangiopancreatography (MRCP) sequences: single-shot rapid acquisition with relaxation enhancement (RARE) and multislice half-Fourier acquisition single-shot turbo spin echo (HASTE) in imaging the pancreaticobiliary system. PATIENTS AND METHODS: The diagnostic accuracy of single-shot RARE and multislice HASTE was studied in 34 subjects who had undergone conventional cholangiopancreatography. Overall image quality, duct conspicuity, image artifact, signal intensity and contrast-to-noise ratios were assessed independently by two radiologists who were unaware of the underlying diagnosis. RESULTS: Both sequences had comparable diagnostic accuracy regarding a normal biliary system, choledocholithiasis, extra-hepatic and intra-hepatic strictures. Single-shot RARE was superior to multislice HASTE in diagnosing a normal pancreatic system, pancreatic and intrahepatic duct strictures, while providing significantly better image quality (mean +/- SE 3.7 +/- 0.07 vs 3.3 +/- 0.08: P = 0.02) and significantly less image artifact (mean +/- SE 3.6 +/- 0.07 vs 3.2 +/- 0.08: P = 0.01). Single-shot RARE provided significantly better duct conspicuity regarding the pancreatic duct within the body (2.7 +/- 0.2 vs 2.1 +/- 0.2: P = 0.003) and tail (2.4 +/- 0.2 vs 1.6 +/- 0.2;P = 0.0001), as well as the intrahepatic ducts (3.0 +/- 0.1 vs 2.6 +/- 0.1: P = 0.004) but there was no significant difference regarding the remainder of the biliary tree. CONCLUSION: Single-shot RARE provides superior image quality, duct conspicuity with the added advantage of less image artifact and shorter acquisition time. However, volume averaging can cause common bile duct stones to be missed. Therefore, multislice HASTE sequences should still be acquired if choledocholithiasis is suspected. Larger studies are required to assess the diagnostic efficacy of single-shot RARE sequences in pancreatic duct and intra-hepatic duct disease.Morrin, M. M. (2000). Clinical Radiology55, 866-873.

Adolescent↗
PubMed2000

Spinal dysraphism at MR urography: initial experience.

PURPOSE: To prospectively evaluate the role of magnetic resonance (MR) urography in the radiologic assessment of patients with spinal dysraphism. MATERIALS AND METHODS: Fourteen patients with spinal dysraphism were referred for MR urography with half-Fourier rapid acquisition with relaxation enhancement (RARE) (repetition time msec/echo time msec = 11.9/95) and RARE (2,800/1,100) sequences on a 1.5-T MR machine. Six patients did not tolerate MR urography owing to claustrophobia (n = 4) or flexion deformities (n = 2), giving a final success rate of 57% (eight patients). Two patients had a single kidney (one after nephrectomy, one with a crossed-fused ectopic kidney). Images were jointly assessed by two radiologists and compared with excretory urographic studies. The signal intensity ratio and contrast-to-noise ratio were also calculated. RESULTS: Visualization of the kidneys, pelvicaliceal system, and ureters was better with half-Fourier RARE than with RARE imaging, whereas visualization of the bladder was comparable with both sequences. The mean signal intensity ratios for half-Fourier RARE and RARE sequences, respectively, were 16.2 +/- 3.65 and 19.2 +/- 3.65 (P =. 58, factorial analysis of variance model), whereas the mean contrast-to-noise ratios were 55.4 +/- 5.16 and 47.8 +/- 5.16 (P =. 34). Cortical scarring was depicted more clearly at MR urography than at excretory urography, whereas a renal calculus seen at excretory urography was not detected at MR urography. CONCLUSION: MR urography was feasible in 57% of patients with spinal dysraphism and is a safe, accurate method of evaluating the upper urinary tract.

Adolescent↗
PubMed1998

Tone burst auditory brain stem response latency estimates of cochlear travel time in Meniere's disease, cochlear hearing loss, and normal ears.

OBJECTIVE: The current study sought to determine whether tone burst auditory brain stem response (ABR) latencies could be used to detect an increase in the cochlear traveling wave velocity in patients with Meniere's disease. BACKGROUND: It has been proposed that the derived band ABR technique can be used to show an increase in cochlear traveling wave velocity in patients with Meniere's disease. The current study sought to replicate these findings using tone burst ABR at frequencies of 0.5, 1, 2, 4, and 8 kHz and intensities from 40-100 dB hearing loss (HL) in 10-dB steps. METHODS: Wave V latency differences between adjacent frequencies were taken to represent the time it takes the traveling wave to travel between the "place" on the basilar membrane where these two frequencies are represented. Thirty-two subjects participated in the project consisting of 10 with normal hearing, 10 with cochlear HL (not caused by Meniere's disease), and 12 with Meniere's disease. RESULTS: There were no significant differences in absolute wave V latencies or in wave V latency differences (travel time estimates) between the groups (repeated measures analysis of variance, p > 0.05). CONCLUSION: These results suggest that wave V latencies and estimates of cochlear travel time cannot be used to distinguish Meniere's disease from other forms of cochlear HL or from normal-hearing ears. The results of this study differ from those using the derived band ABR technique. This difference may be because of the disease state of the authors' subjects or differences in stimulus paradigm.

Adult↗
PubMed1997

Telescoping bronchial anastomoses for unilateral or bilateral sequential lung transplantation: CT appearance.

PURPOSE: To determine the computed tomographic (CT) appearance of telescoping bronchial anastomoses. MATERIALS AND METHODS: CT scans obtained in 36 adult patients with 54 telescoping anastomoses (30 right bronchus, 24 left bronchus) were retrospectively reviewed. Seventeen scans were obtained with 10-mm collimation, one with 5-mm collimation, and 18 with 3-mm collimation. Multiplanar volume reconstruction images were retrospectively generated in 19 patients. CT findings were correlated with fiberoptic bronchoscopic findings and clinical records. RESULTS: Smooth, spherical air collections caused by diverticula of redundant mucosa were seen at the inferior or medial aspect of 22 anastomoses (41%). Endoluminal flaps and linear air collections caused by separation of the invaginated bronchus from the recipient bronchus were seen in 16 anastomoses (30%). Flaps and linear air collections were seen only at the anterior, superior, or inferior aspects of the anastomosis. Flaps and diverticula were more common at right anastomoses than at left anastomoses. No patient with an endoluminal flap or diverticulum at CT had dehiscence at bronchoscopy. Irregular air collections or posterior wall defects were suggestive of dehiscence at four anastomoses (7%). Dehiscence was confirmed bronchoscopically at two of these four anastomoses. CONCLUSION: Endoluminal flaps and linear or spherical air collections can be a normal feature of the telescoping anastomosis and should not necessarily be interpreted as dehiscence.

Adult↗
PubMed1997

Intramural hematoma of the thoracic aorta: MR image findings and their prognostic implications.

PURPOSE: To evaluate magnetic resonance (MR) imaging findings of intramural hematoma of the thoracic aorta and their relationship to prognosis. MATERIALS AND METHODS: MR images of 22 patients with intramural hematoma of the thoracic aorta were reviewed retrospectively. Site, thickness, degree of mural involvement, and signal intensity on spin-echo (SE) and cine gradient-echo (GRE) images of the hematoma were noted. MR findings of patients who did and those who did not develop complications were compared. RESULTS: Hematoma site was the only MR finding that correlated significantly with patient outcome. Complication frequencies in four (80%) of five patients with hematoma of the ascending aorta (type A) and in two (12%) of 17 patients with hematoma of the descending aorta (type B) were significantly different (P = .009). There were moderately strong correlations between days after symptom onset and signal intensity of the hematoma on SE (r = 0.78) and GRE (r = 0.72) images. MR images of two of three patients who developed early-subacute complications showed signal intensity changes of the hematoma that were consistent with recurrent bleeding. CONCLUSION: Patients with MR findings consistent with type A intramural hematoma of the thoracic aorta should undergo surgery. In cases of type B intramural hematoma of the thoracic aorta, MR imaging can be useful for detecting complete resolution or impending complications of the hematoma.

Aged↗