Biomedical subjects

A S Hambye

Publications and source records attributed to A S Hambye.

11 recordsLinked to original sources

PubMed1999

Influence of methodology on the presence and extent of mismatching between 99mTc-MIBI and 123I-BMIPP in myocardial viability studies.

UNLABELLED: Discordant uptake (mismatching) of 123I-labeled beta-methyl-piodophenyl-pentadecanoic acid (BMIPP) less than 99mTc-labeled methoxyisobutyl isonitrile (MIBI) is a good predictor of myocardial viability. However, methodological factors can influence assessment of the presence of mismatching because of differences in background activity between the tracers. In this study, we investigated the influence of methodological parameters on the mismatching between BMIPP and MIBI in patients with chronic ischemic heart disease. METHODS: Polar maps were created to quantify the extent of mismatched tissue measured in 10 patients with myocardial infarction according to three methods for data processing: no correction, subtraction of background activity measured in the left ventricle cavity and dual-window scatter correction. Mismatching was expressed as a percentage of the surface of the left ventricle globally as well as for each arterial territory using a BMIPP uptake of at least 10% less than MIBI as the threshold. The results of dobutamine stress echocardiography and the evolution of the regional contractility at 6-mo follow-up were used as references. RESULTS: Mean background activity in the ventricle cavity was 9.3% of the maximum activity for MIBI and 21.4% for BMIPP before, and 2.8% and 8.3% after scatter correction. Fourteen arterial vascular territories demonstrated baseline wall-motion abnormalities; 9 territories showed contractile reserve with dobutamine stress echocardiography. Significant mismatching was found in 5 of 14 regions without correction, 9 of 14 after scatter correction and 13 of 14 after background subtraction. Compared with the evolution of resting regional contractility at follow-up, optimal results were found when using the scatter-corrected data. Without correction, mismatching between BMIPP and MIBI was partially disguised because of the higher noise level in the iodine images. On the contrary, subtraction of background measured by means of a single region of interest overestimated the magnitude of mismatching due to the heterogeneous background distribution in the ventricular cavity. CONCLUSION: In quantifying the presence and extent of mismatching between MIBI and BMIPP in chronic ischemic heart disease, significant differences in the detection of viability are noted according to the acquisition and processing methods used. Scatter correction of the acquisition data is the most accurate and reliable method for identifying viable myocardium.

Fatty Acids↗

PubMed1999

Nuclear cardiology, Part IV: Viability.

After reading Part IV of this series of nuclear cardiology articles, the reader should be able to describe: (a) the differences between SPECT and PET techniques; (b) the various radiopharmaceuticals and imaging protocols used for detecting viability with SPECT; (c) the different radiopharmaceuticals and imaging protocols used for detecting viability with PET; and (d) the imaging patterns observed after reconstructing myocardial images.

Coronary Disease↗

PubMed1999

Quantification of 99Tcm-sestamibi and 123I-BMIPP uptake for predicting functional outcome in chronically ischaemic dysfunctional myocardium.

Little is known about the usefulness of free fatty acid scintigraphy for assessing viability in chronic ischaemic heart disease. To investigate this, we quantified the uptake of 99Tcm-sestamibi and 123I-BMIPP at rest twice within 6 months in 20 patients with chronic ischaemic left ventricular dysfunction and infarction. Four patterns of the relative distribution of both tracers were observed and classified as normal, mismatched, matched and scar. The proportion of the left ventricular surface corresponding to each pattern was expressed as the percentage of the total surface using a polar map. Between the two studies, the patients either underwent revascularization or were treated conservatively. The quantitative results were compared with those of dobutamine stress echocardiography (DSE) in arterial territories with resting contractile dysfunction and correlated with the evolution of regional and global function at follow-up. At baseline, 25 arterial territories were analysed. Using sestamibi, on average one-third of their surface was considered to be normally perfused. No clear association was found between the percent normally perfused surface and the DSE findings. Adding BMIPP and using a value of > 7% of the arterial surface with BMIPP lower than sestamibi (mismatch) as the cut-off for the significance of viability, 14 of 18 mismatched regions were considered viable by DSE, and six of seven with < 7% mismatched surface or matching were not. Fifteen patients were viable, of whom 13 were revascularized (16 territories). At follow-up, global function improved in 11 of the 15 viable patients, all in the revascularized group. Regional improvement was noted in 11 of 16 revascularized territories, and was associated with a significant increase in sestamibi and BMIPP uptake and in the percent normally perfused myocardial surface. In the five patients without significant viability, no functional deterioration or changes in the quantitative parameters were observed during treatment. The results suggest that quantitative analysis of the uptake of sestamibi and BMIPP is a reliable method to objectively assess the presence of myocardial viability in chronic ischaemic heart disease and to predict functional improvement after revascularization.

Aged↗

PubMed1999

BMIPP imaging to improve the value of sestamibi scintigraphy for predicting functional outcome in severe chronic ischemic left ventricular dysfunction.

UNLABELLED: Mismatching between beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) and perfusion accurately predicts functional outcome after acute myocardial infarction. The current investigation was aimed at evaluating the value of this method to predict the evolution of global function according to the applied treatment in patients with chronic ischemic heart disease. METHODS: Twenty patients with infarction and chronic left ventricular dysfunction were studied (median infarction age 12 wk, range 2 wk-15 y). Radionuclide angiography, two-dimensional echocardiography and BMIPP and gated sestamibi scintigraphy were performed with the patient at rest before and >6 mo after treatment (revascularization in 13 patients and conservative therapy in 7 patients). In 7 patients, radionuclide angiography was repeated after 1 y. RESULTS: On a patient basis, mismatching with BMIPP less than sestamibi was noted in 15 patients at baseline. Of these 15 patients, 11 had significant functional improvement at follow-up versus only 1 of the 5 patients with a matched decreased uptake. Hence, the combined sestamibi/BMIPP was 73% positive and 80% negative in predicting functional outcome, with a global accuracy of 75%. On a segmental basis, using an optimal threshold of uptake defined by receiver operating characteristic curve analysis, sestamibi was only 63% accurate in predicting regional outcome. Adding BMIPP improved the accuracy to 80% (P = 0.001). At follow-up, significant mismatching was still noted in 7 patients in the revascularized group and 1 in the medically treated group. The mismatch was associated with a further increase in ejection fraction at 1-y follow-up in only the revascularized group. CONCLUSION: In patients with chronic left ventricular dysfunction after infarction, a mismatching with BMIPP less than sestamibi reliably identifies jeopardized but viable myocardium and predicts functional recovery with an accuracy similar to that reported in the acute and subacute phases of the infarction.

Aged↗

PubMed1998

Nuclear cardiology, Part III: Scintigraphic evaluation of cardiac perfusion.

OBJECTIVE: After reading Part III of this series of nuclear cardiology articles, the technologist should be able to: (a) compare and contrast radiopharmaceuticals used for myocardial perfusion imaging; (b) describe imaging protocols used for detecting coronary artery disease; and (c) describe imaging patterns seen following reconstruction of myocardial images.

Coronary Circulation↗

PubMed1996

Diagnostic value of Tc-99m sestamibi gated SPECT to assess viability in a patient after acute myocardial infarction.

The case of a 56-year-old woman who was admitted with an acute anteroseptal myocardial infarction showed severely decreased left ventricular function and regional wall motion abnormalities on planar Tc-99m gated blood pool imaging. Tc-99m sestamibi stress SPECT imaging demonstrated residual peri-infarct ischemia. At angiography, a solitary severe proximal left anterior descending stenosis was successfully dilated. Later, because of recurrent chest pain, a second Tc-99m sestamibi stress-rest SPECT was performed to exclude restenosis. Because the question of viability within the infarct region had also been asked, a gated protocol was applied and compared to TI-201 rest-redistribution SPECT. Both tests pointed to the existence of tissue viability in the septal region, without evidence for stress ischemia. The patient was then medically treated. One year later, because of angina, Tc-99m gated SPECT blood pool imaging showed a spectacular increase in left ventricular function and a dramatic improvement in regional wall motion. Angiographic data confirmed these findings and there was no significant restenosis. Thus, Tc-99m sestamibi gated SPECT may be helpful in predicting viability and recovery of function in patients with severely impaired left ventricular regional wall motion after acute myocardial infarction.

Female↗

PubMed1996

240 degrees: why not?

Single photon emission tomographic imaging of myocardial perfusion with 99Tcm-labelled agents is usually performed with single-detector gamma camera systems and 180 degrees anterior data collection. With multi-detector systems, reconstruction over 180 degrees and 360 degrees has been reported. We used a data set of normal subjects to compare both reconstruction methods. In addition, we tested an alternative approach, reconstructing data from 240 degrees acquisitions, excluding the right posterior views, which provide little myocardial information and which are responsible for a reduced signal-to-noise ratio. On the transverse slices, the known apical distortion with the 180 degrees reconstruction was not noted with the 360 degrees or 240 degrees reconstructions. Using semi-quantitative analysis of apical, mid-ventricular and basal short-axis slices, almost complete overlap was observed between the 240 degrees and 360 degrees circumferential profiles of our 20 normal volunteers, except in the inferior wall where a reduction in activity was noted. However, this finding was less pronounced with the 240 degrees than with the 180 degrees reconstruction. The frequent reduction in activity in the anterior wall was more prominent with the 180 degrees than with the 240 degrees and 360 degrees reconstructions. A 240 degrees acquisition represents a useful compromise between 180 degrees and 360 degrees imaging protocols when a single-detector device is used, allowing more homogeneous tracer distribution and a reduction in the apical distortion without material change of contrast or doubling of the acquisition time.

Adult↗

PubMed1995

Failure to label red blood cells adequately in daily practice using an in vivo method: methodological and clinical considerations.

This study was conducted to evaluate the frequency and possible causes of poor red blood cell (RBC) labelling when performing equilibrium gated blood pool (GBP) radionuclide angiography at rest with an in vivo method. The influence of the mode of administration on tagging efficiency was studied by investigating the image quality in 160 patients referred for evaluation of left ventricular (LV) function prior to or after coronary angiography, while using a roughly standardized administration protocol. The patients were subclassified into four groups according to the way both molecules involved in the tagging procedure were administered. When poor image quality was found (in 9.4% of the patients), the labelling efficiency was quantified and the frequency of failed tagging in each group was calculated. A significant association was found between poor labelling and the use of a Teflon catheter or butterfly needle for the injection of the stannous agent. In another 737 patients, in order to avoid the problems observed in the first group, a strict administration protocol was applied to analyse the frequency of poor tagging and its possible causes. Suboptimal image quality was present in 88 patients (11.9%). Quantitatively confirmed poor tagging was present in 36 of the 88 (40.9%, or 4.9% of the whole group); the remaining 52 patients showed borderline normal labelling (> 80% bound fraction). Drug interference was studied by comparing the medications used by the 36 patients showing poor binding with those used by 44 control patients. A significant relationship was found between the use of heparin or chemotherapy and the tagging. The influence of several clinical factors on the labelling was also investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1993

[Determination of thyroid peroxidase antibodies in common thyroid pathology. Methodological and clinical approach].

Thyroid peroxidase antibody levels were measured in 409 patients who came to the thyroid pathology consultation of our Institution between September, 1990, and November, 1991, and were compared with a reference population. In the first 231 patients, we compared the results obtained with two commercial kits. The correlation coefficient between both populations of results was assessed to be 0.919. Only one of the kits was selected later ("Immutest anti-TPOR", Henning, Germany) because normal and pathological values overlapped to a lesser extent. In a population of controls (reference population). 4 cases out of 82 (4.8%) had values exceeding 100 U/ml (arbitrary units), this value being regarded as the boundary of normal conditions. Out of the 409 assays made in patients examined during the thyroid pathology consultation, 137 (33.5%) had pathological values ranging from 100 to 5000 U/ml and even more. Peroxidase antibodies are mainly found in patients with primary hypothyroidism (positive in 82% of cases) and graves' hyperthyroidism (positive in 81%). We have also observed the highest levels in these two conditions. In addition, we have demonstrated a group of patients with normal thyroid conditions who were positive for peroxidase antibodies, sometimes in a family with a history of thyroid pathology. These may be at higher risks to develop hypothyroidism in the future than the general population. A TRH test in some subjects and the clinical evolution of these patients lead us to advocating TPO antibody assay for screening on the first consultation. Endocrine surveillance is advisable in case of positive results.

Antibodies↗

PubMed1992

Kidney depth measured by using 99Tcm-DMSA. Comparison with CAT scan: review of 50 measurements.

Measurement of kidney depths using computed axial tomographic (CAT) scans, considered as the gold standard, has been compared in 25 patients with depth measured using an isotopic method (99Tcm-DMSA). 99Tcm-DMSA underestimates renal depth in 78% of the cases (mean underestimation: 0.78 cm). The correlation coefficient between the two methods is 0.82. As a comparison, kidney depths calculated using Tonnesen's formula are also given and related to CAT scan results. The presence of renal morphological abnormalities in 18% of the studied kidneys allowed the authors to study their potential influence on 99TcmDMSA measurements. They do not seem to be very different from those obtained in morphologically normal kidneys. The different methods for kidney depth measurement described in the literature are briefly reviewed.

Adult↗

PubMed1989

[Bourneville's disease of the bones or metastasis? Apropos of a case].

Tuberous sclerosis or Bourneville's disease is a phakomatosis with common but paucisymptomatic bone localisations. Some osseous lesions, of osteosclerotic type, can be radiologically diagnosed as primary or secondary malignant disorders. We describe a case of Bourneville's disease with bone involvement, radiologically characterized by osteosclerosis areas of the spine and the pelvis. Interestingly, bone scintiscan was normal. The absence of primary malignancy, the stability of control bone X-ray films, the clinical status and the family history, together with the pathognomonic radiological feature of the hands support the diagnosis of tuberous sclerosis with bone involvement.

Aged↗