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N Pocock

Publications and source records attributed to N Pocock.

14 recordsLinked to original sources
PubMed2005

Direct comparison of 18F-fluorodeoxyglucose coincidence gamma camera tomography with gallium scanning for the staging of lymphoma.

BACKGROUND: The present study compared the performance of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) using a coincidence dual-head gamma camera (FDG Co-PET) with 67gallium scinti graphy (GS) in pretreatment staging of lymphoma. METHODS: A total of 46 patients underwent FDG Co-PET, computed tomography (CT) scanning and GS for pretreatment staging of lymphoma (40 newly diagnosed and recurrence) between November 1997 and December 1999. RESULTS: Histological subgroups comprised low grade (8 patients), intermediate grade (25) high-grade (3) non-Hodgkin's lymphoma and Hodgkin's disease (10). Based on clinical assessment, CT scan findings and biopsy, 100 nodal sites and 15 extra-nodal sites were deemed positive. FDG Co-PET was superior to GS in nodal site positivity rate (97%vs 79%, P < 0.0001). Compared with GS, FDG Co-PET detected 39 more abnormal sites in 22 patients (48%), of which 28 sites were validated by biopsy, CT and/or progress FDG Co-PET scanning. There was only one proven false negative FDG site in the spleen. CT + FDG Co-PET led to upstaging in 2 patients (4%), compared to CT + GS. CONCLUSION: FDG Co-PET shows potential for providing an accurate means for pretreatment staging of lymphoma and can detect extra sites of disease activity compared to GS.

Adult↗
PubMed2001

Discordant normal ranges for proximal femur bone density in Australia.

The aim of the study was to investigate the reference ranges currently in use for femoral neck bone mineral density (BMD) in Australia. Representative scans were obtained of the proximal femur from 78 dual-energy X-ray absorptiometry centers across Australia. Femoral neck BMD was standardized using published conversion equations and corresponding T-scores calculated using an Australian reference range (ARR) and using the NHANES-III reference range (NH3RR). Reported T-scores (TR) from the DXA centers were compared with T-scores derived from the NH3RR (TNH) and from the ARR (TA). Examination of the regression lines comparing TR with TNH, and TR with TA, demonstrated that the reference ranges used by centers with Lunar, and some of the Norland and Hologic instruments, differed only slightly from both the NH3RR and the ARR. A number of centers, however, with Norland or Hologic scanners, were using reference ranges which differed from both the NH3RR and ARR. The reference ranges used with these latter Hologic or Norland scanners could result in T-score differences of up to I standard deviation in the clinically relevant T-score range. The NH3RR was compared with the ARR using a set of BMD values covering the clinical range. There was close agreement between TNH and corresponding TA, confirming close agreement between the NH3RR and ARR. There are thus clinically important differences in the reference ranges currently used within Australia for interpretation of femoral neck BMD. For consistency, and in view of its validation, the NH3RR is recommended as the most appropriate Caucasian normal range in Australia. The ARR for femoral neck BMD does not differ significantly from the NH3RR and is also acceptable. Problems relating to the use of discordant BMD reference ranges potentially may exist in other countries.

Absorptiometry, Photon↗
PubMed2001

Future methods in the assessment of bone mass and structure.

There have been major advances in the diagnosis of osteoporosis over the last few decades not only in the definitions that are now used but also in the technology that is available. The future will see further development of the techniques currently in common clinical use, such us dual energy X-ray absorptiometry and quantitative ultrasound. In addition new techniques for assessing bone structure, including MRI and fractal analysis of X-rays, may add significantly to our understanding of the pathophysiology of osteoporosis and to the prediction of fracture risk.

Absorptiometry, Photon↗
PubMed2000

Fluorine-18 FDG dual-head gamma camera coincidence imaging of radiation pneumonitis.

A 69-year-old man with inoperable stage I squamous cell carcinoma of the lung underwent a radical course of radiotherapy combined with platinum-based chemotherapy. Fluorine-18 fluorodeoxyglucose (FDG) imaging with a dual-head coincidence gamma camera system (Co-PET) diagnosed radiation pneumonitis 1 month after completion of radiotherapy, when the clinical and radiographic signs were atypical and more suggestive of carcinomatous lymphangitis. Treatment with oral steroids was begun based on FDG scan findings, with prompt clinical benefit as would be expected for radiation pneumonitis.

Aged↗
PubMed2000

Interpretation of bone mineral density measurement and its change.

Bone mineral density (BMD), an important measurable predictor of osteoporotic fractures, is used as a surrogate definition of osteoporosis, and often as an end point in clinical trials. However, BMD is measured with random error and random fluctuation within individuals. This study addresses two specific questions: Given an observed level of BMD for an individual, what is the individual's likely "true" level? To what extent does an observed BMD change reflect a real change? A Bayesian model was formulated to address these questions, using data from the Dubbo Osteoporosis Epidemiology Study, past clinical trials, and a short-term reliability study in individuals ages 60 yr and older. Measurements of lumbar spine and femoral neck BMD by dual X-ray absorptiometry are highly reliable, with coefficients of reliability ranging from 0.90 to 0.99. Consequently, for an individual, there is good agreement between observed and "true" BMD values. However, the 90% confidence interval for the true level in elderly people and those with low measured BMD values is particularly wide. Using the cutoff of 2.5 standard deviations below the young normal mean as a definition of osteoporosis, the rates of false positives and false negatives can be as high as 20% among individuals ages 80 yr and older. In a typical clinical trial with an overall average increase in BMD of 2%, for a subject whose baseline femoral neck BMD is 0.80 g/cm(2), no conclusion of significant change could be drawn until an observed increase of at least 5.5% or an observed decrease of at least 7.5%. If two measurements were taken at baseline and follow-up, the true change could be detected with an observed increase of 3.5% or an observed decrease of 5%. On the other hand, there needs to be an observed increase of 6.2 and 8.5% before one can be 90% certain that a true increase of 2 and 5%, respectively, has occurred in an individual. This analysis suggests that the diagnosis of osteoporosis based on a single measurement of BMD and point estimates of changes in BMD may be inappropriate and unreliable. We propose that the current practice of informing individuals who have BMD measurements about their actual T- and Z-scores be replaced with a system of reporting in which their osteoporosis probability risk category is conveyed. Also, assessment of change in an individual should take into account the overall change in a population.

Absorptiometry, Photon↗
PubMed1993

Prevention of corticosteroid osteoporosis. A comparison of calcium, calcitriol, and calcitonin.

BACKGROUND: Prolonged corticosteroid therapy increases the risk of osteoporosis and fracture. We studied whether corticosteroid-induced osteoporosis could be prevented by treatment with calcium, calcitriol (1,25-dihydroxyvitamin D3), and calcitonin. METHODS: One hundred three patients starting long-term corticosteroid therapy were randomly assigned to receive 1000 mg of calcium per day orally and either calcitriol (0.5 to 1.0 microgram per day orally) plus salmon calcitonin (400 IU per day intranasally), calcitriol plus a placebo nasal spray, or double placebo for one year. Data on treatment efficacy were available for 92 of these patients. Bone density was measured every four months for two years by photon absorptiometry. There were no significant differences between groups with respect to age, underlying disease, initial bone density, or corticosteroid dose during the first year. RESULTS: Calcitriol (mean dose, 0.6 microgram per day), with or without calcitonin, prevented more bone loss from the lumbar spine (mean rates of change, -0.2 and -1.3 percent per year, respectively) than calcium alone (-4.3 percent per year, P = 0.0035). Bone loss at the femoral neck and distal radius was not significantly affected by any treatment. In the second year, lumbar bone loss did not occur in the group previously treated with calcitonin plus calcitriol (+0.7 percent per year), but it did occur in the group given calcium alone (-2.3 percent per year). The calcitriol group also lost lumbar bone (-3.6 percent per year) but received more corticosteroid in the second year than the other two groups. CONCLUSIONS: Calcitriol and calcium, used prophylactically with or without calcitonin, prevent corticosteroid-induced bone loss in the lumbar spine.

Adolescent↗
PubMed1993

Changes in axial bone density with age: a twin study.

Bone mineral density in adult life, which is an important determinant of fracture risk, is determined by peak adult bone density, achieved in early adulthood and subsequent rates of change during adult life. Cross-sectional twin and family studies indicate that the majority of population variation in bone density may be explained by genetic factors. Although there is evidence for a genetic effect on peak bone mass, it is unknown whether there is a genetic effect on rates of changes in bone density with age. Changes in lumbar spine and femoral neck bone density determined by dual-photon absorptiometry (Lunar DP3) were examined in a cohort of monozygotic (MZ, n = 21, 3 male and 18 female pairs, median age, range, 46; 24-75 years) and dizygotic twins (DZ, n = 19; 43, 25-65 years). The median follow-up was 3 years (range 1.1-5.5 years), with each subject having at least two and up to four bone density assessments. In these twins, genetic factors determine variation in rates of change (% change/year) in lumbar spine bone density, rMZ = 0.93 and rDZ = 0.51, p < 0.02 (one tailed), and Ward's triangle, rMZ = 0.60, rDZ = 0.11, p < 0.05 (one tailed). Model-fitting analysis was also consistent with a genetic effect on rates of change in bone density at the trochanteric site, although such an effect was not shown at the femoral neck. These data demonstrate, for the first time, the possible existence of genetic determinants of rates of change in bone mineral density in adults.

Absorptiometry, Photon↗
PubMed1993

Prevention of corticosteroid bone loss.

Prolonged corticosteroid therapy is known to result in an increased risk of osteoporotic fracture, probably as a consequence of enhanced bone resorption and depressed bone formation. We examined the effects of prophylactic treatment with 1,25-dihydroxyvitamin D3 (calcitonin) and nasal salmon calcitonin on corticosteroid-induced bone loss in 103 patients being treated with long-term corticosteroids for the first time in a randomized, double-masked prospective study. Patients were randomly allocated to one of three groups receiving either calcium supplementation alone, calcium plus calcitriol, or calcium plus calcitriol and nasal salmon calcitonin. Treatment was given for 12 months. Bone mineral density (BMD) was measured every 4 months by dual-photon absorptiometry in the lumbar spine and femoral neck. Calcium supplementation alone did not prevent bone loss at either site. In the lumbar spine calcitriol, with or without nasal calcitonin, significantly reduced bone loss (p < 0.0001). Neither calcitriol alone nor calcitriol with calcitonin prevented bone loss at the femoral neck. These data suggest that treatment with calcium and calcitriol, or with calcium and intranasal calcitonin, greatly reduced or prevented corticosteroid-induced bone loss in the lumbar spine.

Adrenal Cortex Hormones↗
PubMed1993

Radionuclide hepatobiliary scanning in patients with AIDS-related sclerosing cholangitis.

Biliary disease, primarily manifesting as papillary stenosis or sclerosing cholangitis, is being increasingly recognized as a problem in the acquired immunodeficiency syndrome (AIDS) and may be amenable to specific treatment. Ultrasound, followed by endoscopic retrograde cholangiopancreatography (ERCP) for definitive diagnosis, is currently the prime mode of investigation of suspected hepatobiliary diseases in AIDS. There are few published reports of the use of radionuclide cholescintigraphy in the assessment of these patients. This report presents Tc-99m DISIDA cholescintigraphy data from three patients with AIDS-related hepatobiliary disease confirmed by ERCP. Radionuclide cholescintigraphy was abnormal in all three patients. In two of the subjects, there was focal duct dilation with strictures in the biliary tree. The third patient demonstrated diffuse hepatic parenchymal retention with marked delay in tracer washout. Two of the subjects, treated with specific anticryptosporidial therapy, subsequently underwent progress cholescintigraphy. In one of these patients with initial diffuse parenchymal retention, there was marked improvement in scan appearances. The second patient with initial duct dilation had no significant change in scan appearances, but quantitative analysis did demonstrate improvement in hepatobiliary tracer clearance rate. In conclusion, although ERCP remains the gold standard in the diagnosis of AIDS-related biliary disease, radionuclide cholescintigraphy may be a useful modality in these patients as a screening test before proceeding to more expensive and invasive techniques. In addition, quantitative analysis of cholescintigraphy may allow assessment of patient response to specific antimicrobial or surgical intervention.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Corticosteroid effects on proximal femur bone loss.

Prolonged high-dose corticosteroid therapy is known to result in an increased risk of osteoporotic fracture. Reductions in bone density have been demonstrated at the distal radius and lumbar spine in patients receiving corticosteroids; however there have been few studies of bone density in the hip (the most important site of osteoporotic fracture) in this context. To examine the effect of corticosteroids on the hip we measured bone mineral density (BMD) by dual-photon absorptiometry at three sites in the proximal femur as well as the lumbar spine in 32 patients aged 18-77 years who had been treated with corticosteroids (mean daily prednisone dose 12.7 mg) for up to 23 years. BMD was compared with the expected values using age regressions in normal subjects. BMD was significantly reduced in the femoral neck, Ward's triangle, and the trochanteric region (p less than 0.001 all sites). In the lumbar spine BMD was also significantly reduced (p less than 0.001). We also measured BMD serially in 29 patients receiving corticosteroids. BMD measurements were made in 12 patients who had already been treated with long-term corticosteroids at the time of first BMD measurement (chronic group) and from the commencement of corticosteroid therapy in 17 patients (acute group). The mean (+/- SEM) change in BMD (g/cm2 per year) in the lumbar spine and femoral neck were 0.006 +/- 0.006 and -0.021 +/- 0.007, respectively, for the chronic group and -0.02 +/- 0.005 and -0.039 +/- 0.006 for the acute group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Muscle strength, physical fitness, and weight but not age predict femoral neck bone mass.

Hip fractures are the most serious complication of osteoporosis. Although low proximal femoral bone mineral density (BMD) does not cause hip fractures directly, it is clearly a prerequisite for the increased risk associated with aging. To investigate the mechanism of the age-related decline in proximal femoral bone mineral density, we have examined the relative importance of muscle strength, physical fitness, and body mass index (BMI) in addition to age in the determination of proximal femoral BMD in 73 healthy female volunteers age 20-75 years. Muscle strength was an independent predictor of BMD at all three sites in the proximal femur as well as in the lumbar spine and forearm; proximal femur BMD was also predicted by physical fitness. BMI was a positive predictor of bone mass at all sites. In the proximal femur, age was not an independent predictor of BMD at any site. In postmenopausal women muscle strength was a significant predictor of bone mass in the femur and forearm, but not in the spine. However, BMI remained predictive of bone mineral at all sites. Muscle strength, physical fitness, and weight appear to exert independent effects upon bone mass. Age effects may be mediated indirectly through associated changes in these factors. The integrated physical load on the skeleton may be a final common pathway.

Adult↗