[1231-FP-CIT (DaTSCAN) scintigraphy in the differential diagnosis of movement disorders]. / Apport de la scintigraphie par 123I-fP-CIT (DaTSCAN) au diagnostic différentiel des troubles du mouvement.

The diagnosis of idiopathic Parkinson's disease (IPD) remains mostly clinical. Nevertheless, differentiating IPD from essential tremor or other parkinsonian syndromes solely by clinical examination can be challenging in some cases, especially in the early stage of the disease. The introduction of new isotopic functional imaging techniques, and more specifically the labelling of dopamine transporter derivatives, has improved the understanding and early detection of some diseases affecting the basal ganglia. Iodine-123-FP-CIT (DaTSCAN), a (presynaptic) dopamine transporter analogue for nuclear medicine imaging, has recently been introduced for the non-invasive differential diagnosis between IPD and essential tremor or secondary (e.g. drug-related) parkinsonian syndromes. DaTSCAN scintigraphy has also demonstrated some usefulness in the evaluation of other neurodegenerative parkinsonian syndromes such as Lewy-body dementia or multiple system atrophy. For this latter however, the DaTSCAN has to be combined with a second scintigraphy, imaging the post-synaptic dopaminergic receptors, such as the D2-ligand 123I-iodobenzamide. Combining DaTSCAN scintigraphy to a functional study of the brain cortical activity using a brain perfusion scintigraphy or to the evaluation of the cardiac adrenergic system by means of a myocardial MIBG scintigraphy (a norepinephrine storage analogue) can also be helpful to refine the diagnosis. Our experience shows that a good collaboration between the neurologist specialized in movement disorders and the nuclear medicine physician is useful, if not mandatory, to optimize the diagnostic performances of DaTSCAN scintigraphy.

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.

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.

Abnormal BMIPP uptake in chronically dysfunctional myocardial segments: correlation with contractile response to low-dose dobutamine.

UNLABELLED: Discordance between 123I-15-(p-iodophenyl)-3-(R,S)-methyl pentadecanoic acid (BMIPP) and sestamibi uptake has been described as a good predictor of functional recovery in patients with a recent myocardial infarction. The current investigation aimed at evaluating BMIPP as a viability tracer in patients with chronic ischemic left ventricular dysfunction. METHODS: Thirty-one studies were obtained in 25 patients with severe left ventricular dysfunction postinfarction (median infarction age 3.6 mo; range 2 wk-15 yr). All patients underwent dobutamine stress echocardiography and a resting 99mTc-sestamibi/123I-BMIPP SPECT study in a 3-day interval. The relative uptake of the two tracers was compared to the evolution of wall motion during dobutamine infusion in 8 matched myocardial segments. RESULTS: Among the 130 segments with abnormal wall motion at rest, 70 improved under dobutamine. Using sestamibi, a normal uptake was 88% predictive of a positive response to dobutamine, and a decreased uptake of 63% predicted negative stress echocardiography response. In the segments with abnormal sestamibi uptake, adding BMIPP significantly increased the accuracy of scintigraphy to detect residual viability; 28 of 48 segments (58%) with a mismatched pattern demonstrating residual inotropic reserve under dobutamine infusion versus only 5 of 40 segments (13%) with a matched defect. Global agreement between the two approaches was 77%, and positive and negative predictive values for scintigraphy were 72% and 88%, respectively. CONCLUSION: In patients with chronic ischemic left ventricular dysfunction, the combined assessment of metabolism and perfusion with 123I-BMIPP and 99mTc-sestamibi correlates well with the response of wall motion to dobutamine during stress echocardiography and is more sensitive than sestamibi alone for differentiating viable from scar segments.

Comparison of modified technetium-99m albumin and technetium-99m red blood cells for equilibrium ventriculography.

UNLABELLED: A newly developed modified form of 99mTc-labeled human serum albumin reconstituted from a kit (99mTc-dimercaptopropionyl-human serum albumin; 99mTc-DMP-HSA) was prospectively compared to 99mTc-labeled red blood cells (RBC) in patients referred for equilibrium radionuclide ventriculography at rest to evaluate its potential use as a blood-pool imaging agent. METHODS: A Paired comparison between 99mTc-DMP-HSA and either in vitro or in vivo 99mTc-labeled RBC was performed within 2 days in 20 patients'. For each study, two sets of images were acquired, starting at 15 min and 180 min postinjection, respectively. Each set consisted of a gated blood-pool cardiac study and a planar static image centered on the patient's thorax. All data were processed by two independent observers. Early and late postinjection parameters were calculated: ejection fraction (EF) value, activity within the main organs surrounding the left ventricle (LV), ratio of activity between the LV and these surrounding organs for each study separately, and temporal (late/early) evolution of the intraorgan activities and of the LV/organ ratios after decay correction. RESULTS: The images and the visual wall-motion analysis were of good quality with both agents in most patients, without significant image degradation at 180 min postinjection. Calculated EF values were highly comparable with the two tracers. Interobserver variability was 0.17% (RBC) and 1.08% (DMP-HSA) for the early EF value (EF1), and 0.62% (RBC) and 0.27% (DMP-HSA) for the late EF (EF2). Mean difference between EF2 and EF1 was 0.74% (Observer 1) and 0.28% (Observer 2) for 99mTc-RBC, and -2.88% (Observer 1) and -2.07% (Observer 2) for 99mTc-DMP-HSA. When comparing 99mTc-DMP-HSA to 99mTc-RBC the mean difference was 1.27% (Observer 1) and 0.36% (Observer 2) for EF1, and -2.35% (Observer 1) and -1.99% (Observer 2) for EF2. Also, the biodistribution and temporal evolution of the organ repartition of both compounds were stable and similar, with values of late/early activity ratios very close to one for all the studied organs [mean intraorgan ratio: 0.946 for 99mTc-RBC (range: 0.881-1.086) and 0.979 for 99mTc-DMP-HSA (range: 0.914-1.141); mean late/early LV/organ ratio: 0.964 for 99mTc-RBC (range: 0.919-1.016) and 0.967 for 99mTc-DMP-HSA (range: 0.912-1.035)]. CONCLUSION: Paired comparison of kit-prepared 99mTc-DMP-HSA to 99mTc-labeled RBC demonstrated that both agents were very closely related regarding as well the calculated EF value as the in vivo stability up to more than 3 hr postinjection. Technetium-99m-DMP-HSA may constitute a practical and useful replacement for 99mTc-labeled RBC.

SPET-generated colour-coded polar maps to quantify 99Tcm-MIBI and 123I-BMIPP uptake in chronically dysfunctional myocardium: comparison with coronary anatomy and wall motion.

The combined use of 123I-BMIPP and 99Tcm-MIBI SPET imaging has been proposed as an alternative to PET for the non-invasive detection of jeopardized myocardium after a myocardial infarction, a mismatch accurately indicating jeopardized but still viable tissue. In this paper, a new quantitative approach is described, expressing the presence and degree of mismatch as the percentage of the left ventricular surface globally as well as for each major epicardial artery by means of clearly identified colour-coded polar maps. With this method, the relative proportion of normal and scar tissue, each characterized by a specific colour, is measured using thresholds of 99Tcm-MIBI uptake of 60% and 30% of the expected mean normal value respectively, whereas the presence and extent of mismatch between 99Tcm-BMIPP and 99Tcm-MIBI are calculated only between these two thresholds, typically corresponding to a reduction in flow associated with a possible but uncertain post-revascularization recovery. Applied to 15 patients with severely impaired left ventricular function after a myocardial infarction, small intra- and inter-observer differences were noted in the assessment of the relative proportion of normal, mismatched and scar tissue. More specifically, analysing the variability in the calculated percent mismatch, good reproducibility was observed, with intra- and inter-observer correlation coefficients of 0.96 and 0.94 respectively, a mean (+/- S.D.) intra-observer difference of 0.25 +/- 2.0% for the left ventricle globally, 1.65 +/- 2.9% for the left anterior descending artery (LAD), -1.56 +/- 3.6% for the left circumflex artery (LCX) and -1.24 +/- 2.8% for the right coronary artery (RCA) territories, and mean inter-observer variability of 0.91 +/- 2.4% for the left ventricle globally, -1.51 +/- 3.0% for the LAD, -0.53 +/- 2.9% for the LCX and -0.34 +/- 3.9% for the RCA territories. Using the second standard deviation of the inter-observer difference as a criterion of significance, a significant mismatch between 99Tcm-BMIPP and 99Tcm-MIBI was noted in 13 arterial territories, corresponding to significant stenoses on coronary angiogram and/or wall motion abnormalities in all cases. These results suggest that this new quantitative method, showing good reproducibility, may constitute a reliable and interesting tool for the non-invasive evaluation of myocardial viability with SPET.

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.

Can we rely on 99Tcm-sestamibi gated tomographic myocardial perfusion imaging to quantify left ventricular function? A comparative study with classical isotopic techniques for the measurement of ejection fraction.

The assessment of left ventricular ejection fraction is an important element in the evaluation of cardiac performance, and one of the most commonly performed tests in nuclear cardiology. The aim of this study was to evaluate the accuracy and reliability of ejection fraction values calculated from ECG-gated myocardial perfusion single photon emission tomography (GSPET) in comparison with standard scintigraphic methods. Eight-frame gated SPET was recorded 60-90 min after the injection of 99Tcm-sestamibi at rest. The ejection fraction was calculated using a semi-automatic edge-detection technique based upon a threshold-searching method and compared with values obtained from first-pass (FPRNA) or equilibrium radionuclide angiography (ERNA) in 60 and 40 patients respectively with a broad range of ejection fraction values. Very good reproducibility was noted, with an inter- and intra-observer variability of -0.2 +/- 3.5% (range -7.6 to 6.9%, r = 0.97) and -0.2 +/- 2.2% (range -5.9 to 3.5%, r = 0.99) respectively. Similarly, a high concordance was found between GSPET and FPRNA and between GSPET and ERNA over the range of ejection fraction values (13 to 77%), the mean (+/-S.D.) difference being 0.8 +/- 3.8% (r = 0.97, P = N.S.) and 0.03 +/- 5.3% (r = 0.94, P = N.S.) respectively. Applying the Bland-Altman plot, no systematic bias of one method related to the other was observed, even at extreme ejection fraction values. Gated myocardial perfusion SPET with a 99Tcm tracer thus offers a unique opportunity to quantify cardiac performance and perfusion simultaneously and non-invasively.

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.

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.

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.

Nuclear cardiology, Part II: Scintigraphic evaluation of cardiac function.

OBJECTIVE: Different methods are currently available to assess cardiac function, especially left ventricular ejection fraction, using either planar or tomographic imaging, first-pass or equilibrium techniques, and blood-pool or myocardial perfusion agents. This is the second article of a four-part series on nuclear cardiology. In this article the authors review the most widely used radiopharmaceuticals and methodologies.

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.

Nuclear cardiology, Part I: Anatomy and function of the normal heart.

This is the first article of a four-part series on nuclear cardiology. This article introduces and reviews the anatomy and function of the normal heart. Future articles will develop the contribution of nuclear medicine techniques in evaluating myocardial perfusion, function and viability. This article describes the external and internal features of the heart and its vascularization, conducting system and physiological function. After reading this article, the reader should understand the anatomy and the function of the normal heart.

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.

Determination of systolic thickening index with gated Tc-99m sestamibi SPECT. A new parameter of myocardial viability?

Myocardial perfusion imaging with Tc-99m MIBI SPECT may underestimate the amount of viable myocardium in patients with coronary artery disease and prior infarction. Electrocardiogram gating could potentially better correlate with the presence of jeopardized myocardium, since it allows the evaluation of systolic contractility parameters in addition to the assessment of perfusion. Using the diastolic and systolic bull's eyes of a rest Tc-99m MIBI-gated SPECT study to generate an index of systolic thickening, we clearly observed an impaired contractility in the anterior and septal walls in a patient with multiple vessel disease and a mild mid-left anterior descending stenosis, despite a normal tracer uptake. Confirmation of the index of systolic thickening findings was obtained by rest/redistribution TI-201 SPECT, showing decreased anteroseptal perfusion on the early images with almost complete perfusion. Gating myocardial perfusion imaging seems helpful to identify myocardium at risk. It can aid in the evaluation of the physiological significance of mild coronary artery disease, sometimes insufficient to result in perceptible flow disturbances but already responsible for contractility abnormalities, especially when a large arterial territory is involved.

[Determination of thyroid peroxidase antibodies in common thyroid pathology. Methodological and clinical approach]. / Dosage des anticorps anti-thyroperoxydase en pathologie thyroïdienne courante. Approche méthodologique et clinique.

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.

[Bourneville's disease of the bones or metastasis? Apropos of a case]. / Maladie de Bourneville osseuse ou métastases? A propos d'un cas.

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.

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)

Diagnostic value and incremental contribution of bicycle exercise, first-pass radionuclide angiography, and 99mTc-labeled sestamibi single-photon emission computed tomography in the identification of coronary artery disease in patients without infarction.

BACKGROUND: The diagnostic value and incremental contribution of different noninvasive tests to the identification of coronary artery disease in 128 patients from a general population with intermediate pretest likelihood (48.0%) were determined by ordered logistic regression analysis and receiver-operating characteristic (ROC) curves. METHODS AND RESULTS: Patients referred for suspicion of coronary heart disease were submitted to bicycle exercise testing under clinical and electrocardiographic control. AT peak exercise, first-pass radionuclide angiography was performed after injection of 99mTc-labeled sestamibi, followed by single-photon emission computed tomographic (SPECT) acquisition. A comparative rest study was obtained within 1 week, and qualitative and quantitative analysis was applied to assess the presence and extent of disease. With coronary angiography and 50% stenosis used as a standard, the discriminative accuracy of each test was calculated. The accuracies to diagnose coronary heart disease were 71.3% +/- 4.7% for the bicycle test, 66.7% +/- 5.3% for radionuclide angiography, and 81.6% +/- 3.9% for the SPECT data. By ROC curves, the optimal criteria for positivity were determined for the visual and quantitative analysis for both presence and extent of coronary artery disease. Results of visual and quantitative SPECT were compared in terms of area under the ROC curves. The diagnostic performances showed no significant difference, ranging from 74.3% to 81.6%. The first-pass radionuclide angiographic and SPECT data were added progressively to the stress testing to evaluate their incremental diagnostic contribution. Only the addition of SPECT results significantly increased the accuracy to 85.6% +/- 3.3% (p < 0.0001). CONCLUSION: Exercise electrocardiography and first-pass radionuclide angiography showed comparable accuracy to detect coronary artery disease. However, the combination of exercise testing and visual SPECT analytic data sufficed to ensure diagnostic accuracy, without significant benefit from the addition of other tests or the application of quantification.