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Biomedical subjects

H Ham

Publications and source records attributed to H Ham.

At least 37 records · Page 2Linked to original sources
PubMed2000

NORA: a simple and reliable parameter for estimating renal output with or without frusemide challenge.

The aim of this study was to evaluate a simple parameter describing renal output, namely NORA (normalized residual activity). We first compared, in a simulated model, different parameters of transit to an ideal standard; we then compared, in a clinical study, NORA and output efficiency. 123I-hippurate, 99Tcm-DTPA and 99Tcm-MAG3 plasma curves, each with two levels of renal clearance, were convoluted by means of different types of simulated retention functions, with different mean transit times. On the reconstructed renograms, several parameters reflecting renal transit were determined and compared with mean transit time. In a second step, in 33 patients, we compared output efficiency and NORA (i.e. the residual renal activity), normalized by the renal activity at 2 min. These two parameters were calculated at the end of the renogram, at the end of the frusemide test and after the micturition phase. In the simulated model, both output efficiency and NORA were only slightly influenced by the level of overall renal function. In the clinical study, a good correlation was found between output efficiency and NORA, whatever part of the study considered (renogram, frusemide test, post-voiding image). NORA is a simple and reliable parameter that allows quantification of renal output; it is almost independent of the level of renal function and can be used whatever the timing of the frusemide injection.

Adolescent↗
PubMed2000

Inter-observer reproducibility of relative 99Tcm-DMSA uptake.

99Tcm-DMSA planar images of 49 randomly selected patients (10 adults, 39 children) were sent to 15 physicians at various centres in Belgium. They were asked to calculate, using their own routine program, the relative uptake (expressed as a percentage) of each kidney. The data were sent on disks formatted so that they could be read by all participants, using their own computer systems. For each scan, the inter-observer variability was expressed using the maximum difference and the standard deviation of left renal uptake. Left renal uptake measured by the 15 observers in the 49 patients was 29.0-72.0% (mean +/- s = 49.8 +/- 6.4%). The maximum differences in left renal uptake ranged between 1.7% and 12.0% (4.5 +/- 2.6%); however, the maximum difference did not exceed 8% in about 90% of the patients. The standard deviations of the individual left renal uptake were between 0.6 and 3.9 (1.3 +/- 0.8). The standard deviations were significantly higher in adults (mean standard deviation = 2.05) than in children (mean standard deviation = 1.12) (P < 0.001); this was probably related to the high background observed in three adults with severe renal impairment. Indeed there was a significant correlation (P < 0.001) between the standard deviation and both the signal-to-noise ratio and the degree of asymmetry between the right and left kidneys. The differences between right and left kidney uptake were systematically lower for some observers, suggesting an influence of the calculation programs.

Belgium↗
PubMed2000

Should nuclear medicine physicians give the results of radioisotope examinations directly to patients?

Patients often ask for the results after a radioisotope procedure, which can make nuclear medicine physicians feel uncomfortable. In Belgium, nuclear medicine physicians are not supposed to disclose results directly to patients, but to send them to the referring physician. We undertook this work to determine the official rules and practical attitudes in other countries. An introductory letter and a questionnaire were sent to 103 eminent nuclear medicine specialists from 37 countries. Seventy responses (32 countries) were received. Official rules seemed to exist in only seven countries. Most of the respondents indicated that their attitude depended on the clinical situation and the results of the test. Many respondents emphasized that, while in some situations the results should be communicated directly to patients in order to initiate treatment rapidly, in other situations, such as cancer, the referring physician was better suited to disclose the results. The advantages and drawbacks of different attitudes are discussed. Practically and universally applicable rules are difficult to establish, but choosing one solution remains preferable to no standardized attitude at all. An official body, including the medical community, representatives of the population and legal experts, should define an official rule which should be widely communicated, stressing its advantages and drawbacks. In practice, all nuclear medicine physicians would have to do would be to stick to the rule.

Ethics, Medical↗
PubMed2000

Factors influencing the accuracy of renal output efficiency.

Output efficiency (OE) has been proposed as an objective tool for the estimation of renal emptying. The aim of this paper was to evaluate some factors that may affect the value of this parameter obtained by a 99Tcm MAG3 renogram. In 22 patients, the effect of different types of renal background correction was calculated. In 10 patients, simultaneous gamma camera renography and multiple blood sampling allowed the error of using a heart curve instead of a plasma curve to be evaluated. Finally, an evaluation was carried out on the effect of neglecting the change of plasma activity between the end of the furosemide acquisition and the post-micturition view obtained after repositioning of the patient on the gamma camera: 142 patients who had had multiple blood sampling were retrospectively selected for that purpose. It has been shown that all these factors may significantly affect the value of OE, particularly in cases with poor renal drainage. Unless standardization of the procedure is introduced for some of these factors, the cut-off levels for good, fair and poor drainage may vary between centres.

Algorithms↗
PubMed2000

A multicenter trial on interobserver reproducibility in reporting on 99mTc-DMSA planar scintigraphy: a Belgian survey.

UNLABELLED: Conflicting opinions have been expressed regarding reproducibility in 99mTc-dimercaptosuccinic acid (DMSA) planar renal image interpretation. The purpose of this investigation was to determine the level of interobserver variability among a large group of Belgian nuclear medicine physicians who evaluated a randomly selected series of DMSA planar scintigraphic examinations performed on children and adults. METHODS: All Belgian nuclear medicine centers (n = 82) were invited to participate in a reproducibility study on 99mTc-DMSA scintigraphy. 99mTc-DMSA scans obtained on 10 adults and 40 children were randomly selected from the databases of 2 hospitals. Those participating in this investigation (65 centers = 79%) received a series of computer disks containing 50 99mTc-DMSA studies. To avoid potential problems related to unfamiliar display, the disks were formatted to be interpretable using the participants' own computer systems. Each participant was then free to use his or her usual display (hard copies, contrast enhancement, color scale, gray scale, and so forth). For each kidney, the observers had to choose between the following answers: normal, abnormal, equivocal, and lack of quality. RESULTS: Forty-two responses were obtained from a wide variety of institutions and from observers with different levels of experience in interpreting 99mTc-DMSA scintigraphy. Altogether, the following data were obtained: 60.8% normal, 25.2% abnormal, 7.0% equivocal, and 3.2% lack of quality. The median percentage of agreement (overall reproducibility) for the 42 observers was 92%. When the results of all 42 observers were compared, the median agreements on normality and abnormality were 93.5% and 90.5%, respectively. In a small number (n = 4) of kidneys, reproducibility was poor and ranged from 51% to 70%. Except for 2 outliers, all observers had almost the same level of performance. CONCLUSION: A large number of Belgian nuclear medicine physicians participated in evaluating a large randomly selected sample of 99mTc-DMSA studies, and excellent interobserver agreement was found.

Adolescent↗
PubMed2000

[Should we give the examination results to the patients?].

Immediately after medical imaging procedures, patients often ask for the results of their examination. Such a request is very uncomfortable for the physician performing the examination, who usually does not know the whole medical file, the psychological status of the patient, how he is informed about his illness, etc. By the means of a questionnaire we asked belgian nuclear medicine physicians about the frequency of such situations and about their practical attitude. 204 questionnaires were sent; we received 119 answers (58%) after a 6 weeks delay. In more than 85% of the cases, this situation occurs regularly, and more than 50% of the participating physicians encounter the problem in more than 20% of the cases. Less than 10% of the participating physicians never give any result to the patient asking for it, while more than 20% always give it. Most of the physicians takes into account the clinical situation of the patient. Unfortunately, the official guidelines do not help to clarify the situation. This work confirms that physicians who perform diagnostic procedures frequently encounter difficulties in patients information. It would be necessary that all people who are concerned by this problem collaborate in order to define a clear and accurate attitude which would be easily applicable in our daily clinical practice.

Attitude of Health Personnel↗
PubMed1999

Prescription attitudes among gynecologists towards two particular risk factors of osteoporosis: the patient's age and her bone mineral density.

OBJECTIVE: The present report assesses, among Belgian gynecologists, the effect of age and bone mineral density on osteoporosis prescription strategy in postmenopausal women. METHODS: Charts of postmenopausal women were summarized. We constructed cases by modifying some parameters. Ten years of age were added or subtracted to the real age of the patient. The bone mineral density (BMD) result was also modified (three levels: normal BMD, osteopenia, osteoporosis). A total of 612 cases were constructed. Twelve cases were sent out of these 612 files to every Belgian gynecologist (n = 1010). For each chart the gynecologists were asked whether they would treat the patient with HRT. They were also asked whether they would prescribe other therapies than HRT and if so, which ones. RESULTS: The chance to have an osteoporosis prevention or treatment prescribed increased when BMD decreased (respectively 57.4% for normal BMD, 73.1% for osteopenia cases and 89.4% for osteoporosis cases; P < 0.001). HRT was the most frequently prescribed medication (67% of the cases), but its prescription rate does not reflect only osteoporosis prevention. Nevertheless, for similar cases with osteopenia, the HRT prescription rate increased by a factor 1.25 and for similar cases with osteoporosis, HRT prescription rate increased by a factor 1.39. Calcium was the 2nd most frequent prescribed regimen. It was prescribed in 17% of the cases. A 3.4-fold increase for osteopenia cases and 7.6-fold increase for osteoporosis cases was observed, compared to women with normal BMD. When calcium was prescribed, it was in association with HRT in 64% of the osteopenia cases and in 76% of osteoporosis cases. Other drugs were less often prescribed. For the "younger age group", that is, with a mean age of 55 years, a prescription rate of 82.9% for any osteoporosis regimen was reached, whereas in the age group that was 10 years older a 20% lower prescription rate was reached (62.6%, P < 0.001). This was mostly due to a decrease in HRT prescription. CONCLUSIONS: Prescription of medication known to reduce osteoporosis occurred more often in cases with low BMD. In the older patients with osteoporosis, gynecologists prescribed HRT less frequently. This was not compensated by a higher prescription rate of other medication.

Adult↗
PubMed1999

Perception of osteoporosis by Belgian women who work in a university hospital.

Campaigns to increase 'awareness' of osteoporosis have been organized. The aim of this study was to assess how Belgian women who benefit from superior conditions favoring 'awareness' perceive osteoporosis as being an important disease. A survey sent to the private home of all the women working in a university hospital in Brussels (n = 1154). From a list of 13 diseases the women were asked to rank, by order of importance, the five which they found to be the most important for a woman of their age. They were also asked about visits to physicians, and screening procedures. The response rate was 55.4%. A high uptake of medical visits and screening procedures was reported: 89% of the women had seen a general practitioner or a gynecologist and 81.6% had undergone at least one gynecologic examination during the previous year. Three times more women had ever undergone mammography than a bone mineral density (BMD) measurement. Overall, 18.1% reported having had a BMD measurement in the past. In women over 50 years, 61% reported having had a BMD measurement and 92.7% having had a mammogram. Osteoporosis was ranked among the five most important diseases by 19.4% of women before the age of 50 years and by 39.3% after that age, far behind breast cancer (respectively 86.3% and 77.7%) and uterine cancer (respectively 74.2% and 58.0%). Thus even among a population of women who benefit from superior conditions for information and screening, the perception of osteoporosis remains low, as does the uptake of osteoporosis screening.

Absorptiometry, Photon↗
PubMed1999

Relative 99mTc-MAG3 renal uptake: reproducibility and accuracy.

UNLABELLED: The aim of this study was to estimate the reproducibility and accuracy of 99mTc-mercaptoacetyltriglycine (MAG3) relative percentage uptake. METHODS: Reproducibility was evaluated on healthy volunteers who were submitted twice to a 99mTc-MAG3 renographic study, which used different uptake algorithms, different background corrections and different time intervals. Accuracy was evaluated in a group of patients with symmetrical or asymmetrical relative renal function, who underwent both 99mTc-dimercaptosuccinic acid (DMSA) and 99mTc-MAG3 studies, using the DMSA relative percentage uptake as a reference. RESULTS AND CONCLUSION: The methods that combined the best reproducibility and accuracy for estimating 99mTc-MAG3 left-to-right uptake ratio were the integral method, with subrenal or perirenal background correction, and the Patlak-Rutland plot. The use of the integral method without background correction introduced a systematic bias, whereas the slope method resulted in high variability. Therefore these methods cannot be recommended.

Adult↗
PubMed1997

Factors influencing the prescription of hormone replacement therapy.

OBJECTIVE: To assess the effects of age, bone mineral density, risk of cardiovascular disease, and of breast cancer on the prevalence of hormone replacement therapy (HRT) prescriptions. METHODS: Seventeen charts of postmenopausal women were summarized. For each chart, we constructed 36 different cases by modifying the age (two levels), the bone mineral density (three levels), the cardiovascular risk (three levels), and the breast cancer risk (two levels). Twelve cases of these 612 files were sent to each Belgian gynecologist (n = 1010). RESULTS: Overall, HRT was prescribed in 67% of the cases. It was prescribed in 54.6% of women who had a normal bone mass, 67.9% of women with a low bone mass, and 79.0% of those with osteoporosis (P < .001). The prescription rate was higher in younger women (mean +/- standard deviation 55 +/- 4 years) than in their peers who were 10 years older (79.3% versus 55.2%; p < .001). No significant variation was observed in relation to the cardiovascular risk profile or to breast cancer risk. CONCLUSION: Osteoporosis is associated with an increased rate and older age with a decreased rate of HRT prescription, whereas no difference is observed in association with cardiovascular or breast cancer risk.

Age Factors↗