Biomedical subjects

J Darcourt

Publications and source records attributed to J Darcourt.

At least 19 recordsLinked to original sources

PubMed2007

99mTc-HMPAO and 99mTc-ECD brain uptake correlates of verbal memory in Alzheimer's disease.

AIM: Technetium-99m hexamethylpropylene amine oxime ((99m)Tc-HMPAO) and technetium-99m N,N-1,2-ethylene diylbis-Lcysteine diethyl ester dihydrochloride ((99m)Tc-ECD) SPECT are widely used in Dementia Clinics for early and differential diagnosis. They have been shown to perform differently in Alzheimer's disease (AD), but the impact of such differences on both research and clinical work is unknown. We investigated the differences between the 2 compounds in research work by assessing correlation between performance on a verbal memory task and cerebral perfusion in 2 matched groups of AD patients. METHODS: Nineteen pairs of patients with mild to moderate AD undergoing SPECT with either 99mTc-HMPAO or (99m)Tc-ECD were retrospectively selected in a Memory Clinic. Patients were matched for sex, age (+/-3 years) and the Mini-Mental State Examination score (+/-2 points) with a case-control procedure, thus obtaining 2 well-matched groups. The score on the Grober-Buschke selective reminding test (SRT) was correlated with SPECT in each group by means of statistical parametric mapping 99 (height threshold: P<0.01). RESULTS: (99m)Tc-HMPAO SPECT yielded 3 significant correlation clusters involving inferior and middle frontal gyri, para-hippocampal gyrus and putamen in the right hemisphere; the middle and superior temporal gyri, insula and claustrum in the left hemisphere. (99m)Tc-ECD gave a significant cluster of correlation in left postcentral gyrus and inferior parietal lobule. CONCLUSION: (99m)Tc-HMPAO SPECT correlation sites seem more consistent than (99m)Tc-ECD ones with the neurophysiological models of verbal memory, as designed both in normal individuals and in pathological conditions. The demonstration of such relevant differences introduces a source of variability among studies performed with either of the 2 compounds, which must be considered when interpreting results.

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PubMed2006

From the molecular characterization of iodide transporters to the prevention of radioactive iodide exposure.

In the event of a nuclear reactor accident, the major public health risk will likely result from the release and dispersion of volatile radio-iodines. Upon body exposure and food ingestion, these radio-iodines are concentrated in the thyroid, resulting in substantial thyroidal irradiation and accordingly causing thyroid cancers. Stable potassium iodide (KI) effectively blocks thyroid iodine uptake and is thus used in iodide prophylaxis for reactor accidents. The efficiency of KI is directly related to the physiological inhibition of the thyroid function in the presence of high plasma iodide concentrations. This regulation is called the Wolff-Chaikoff effect. However, to be fully effective, KI should be administered shortly before or immediately after radioiodine exposure. If KI is provided only several hours after exposure, it will elicit the opposite effect e.g. lead to an increase in the thyroid irradiation dose. To date, clear evaluation of the benefit and the potential toxicity of KI administration remain difficult, and additional data are needed. We outline in this review the molecular characterization of KI-induced regulation of the thyroid function. Significant advances in the knowledge of the iodide transport mechanisms and thyroid physiology have been made. Recently developed molecular tools should help clarify iodide metabolism and the Wolff-Chaikoff effect. The major goals are clarifying the factors which increase thyroid cancer risk after a reactor accident and improving the KI administration protocol. These will ultimately lead to the development of novel strategies to decrease thyroid irradiation after radio-iodine exposure.

Animals↗

PubMed2006

Lack of initiative and interest in Alzheimer's disease: a single photon emission computed tomography study.

Apathy is defined as a lack of motivation. The aim of this study was to investigate the relation between two major dimensions of apathy (lack of initiative and lack of interest) and brain perfusion. in patients with Alzheimer's disease (AD). Brain perfusion was measured by single photon emission tomography (SPECT). Thirty-one AD patients were included. Lack of initiative and interest were assessed with the Apathy Inventory. Nineteen AD subjects presented a lack of initiative and interest pathological score whereas 12 AD subjects did not. The lack of initiative and interest score correlated significantly with the right frontal and the right inferior temporal lobes. The AD patients with lack of initiative and interest showed a significantly lower perfusion in the right anterior cingulate than the AD patients without lack of initiative and interest. These results derive from rather small subgroups of patients but have the interest to dismantle the complementary aspects of emotion and motivation in apathy and suggest that the latter one is more related to cingulate area.

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PubMed2005

[Role of imaging in the evaluation of axillary nodes and metastatic disease from breast carcinoma].

Disease staging of patients with breast cancer is based on the probability of metastatic disease, the reliability of complementary examinations, and therapeutic possibilities, evaluated on a cost/benefit basis. For regional disease staging, nodal status can be assessed by ultrasound, and the value of this approach can be optimized by imaging-guided biopsies. Ultrasound examination of nodes upstream of the sentinel node allows determination of the utility of this node and the indications for axillary resection. Work-up of metastatic spread is performed only after evaluation of risk factors for metastasis. Prior to therapy, and in the absence of any clinical warning signs for resectable tumors, there are no indications for imaging, which is reserved solely for locally advanced tumors.

Axilla↗

PubMed2004

Brain perfusion correlates of the apathy inventory dimensions of Alzheimer's disease.

BACKGROUND: Apathy is defined as a lack of motivation in behavior, cognition and affect. This syndrome is frequent in various neuropsychiatric diseases but little is known about its pathophysiology. OBJECTIVES: The aim of this study was to investigate the metabolic correlates of the behavioral, cognitive and emotional, aspects of apathy in Alzheimer's disease (AD). METHOD: Thirty AD patients were included. Lack of initiative, lack of interest and of emotional blunting were assessed with the Apathy Inventory (IA), a tool designed to provide a separate assessment of the behavioral, cognitive and emotional, aspects of apathy. Brain perfusion was measured by (99m)Tc-labeled bicisate (ECD) single photon emission tomography. RESULTS: The Statistical Parametric Mapping software provides negative correlation between IA total score and brain perfusion in left and right superior orbito-frontal gyrus, and to a lesser extent in left middle frontal gyrus (BA10). Lack of initiative score was negatively correlated with perfusion in right anterior cingulate cortex. Lack of interest score was negatively correlated with perfusion in right middle orbitofrontal gyrus). Emotional blunting score correlated negatively with in left superior dorsolateral prefrontal cortex activity. CONCLUSION: These results underline that the cognitive, behavioral and affective components of motivation are mediated by different fronto-sub-cortical circuits and are differently lateralized. In particular, left prefrontal hypoperfusion is involved in emotional blunting, as it was often demonstrated in depressive disorders. These distinct components of apathy may be targeted by different therapeutic means, in which dopaminergic enhancement might play a major role.

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PubMed2004

[Neoadjuvant chemotherapy for symptomatic non operable grade II fibrillary astrocytoma in adults].

We collected 6 case-reports of symptomatric non removable low grade fibrillary astrocytoma of adults treated with a procarbazine-CCNU-vincristine chemotherapy regimen. All patients had drug-resistant epilepsy but brain imaging was stable. Total gross resection was rejected because of Volume or tumor location. After 4 to 7 cycles of chemotherapy, 2 patients had partial response and one minor response on brain MRI. All of them were seizure-free. Progression free survival was not reached at 5 Years. Up-front chemotherapy for low-grade astrocytomas may be useful and has to be prospectively evaluated.

Adult↗

PubMed2001

Perfusion brain SPECT and statistical parametric mapping analysis indicate that apathy is a cingulate syndrome: a study in Alzheimer's disease and nondemented patients.

Apathy is the most frequent behavioral symptom in Alzheimer's disease and is also frequently reported in other brain organic disorders occurring in the elderly. Based on the literature, we hypothesized that apathy was related to an anterior cingulate hypofunction. Forty-one subjects were studied. According to ICD 10 diagnostic criteria, 28 patients had Alzheimer dementia (demented: diagnostic group 1), and 13 had organic personality disorders or mild cognitive impairment not attributable to dementia (nondemented: diagnostic group 2). Apathy was evaluated by the Neuro-Psychiatric Inventory. As a result each diagnostic group was divided into two symptomatic subgroups: apathetic or nonapathetic. Brain perfusion was measured by (99m)Tc-labeled bicisate (ECD) brain SPECT and the images were compared using Statistical Parametric Mapping (SPM96). We began by comparing apathetic vs nonapathetic patients, whatever their diagnostic group (whole population), then analyzed them within each group. Twenty-one subjects were apathetic (14 in group 1 and 7 in group 2) and 20 were not (14 in group 1 and 6 in group 2). For the whole population, the Z map showed a significant decrease in ECD uptake for the apathetic patients in the anterior cingulate (P < 0.002) bilaterally. This area was also identified as hypoactive by SPM analysis in the demented (P < 0.035) and in the nondemented (P < 0.02) apathetic patient groups. Finally, conjunction analysis indicated that the anterior cingulate was the common hypoactive structure of the two apathetic subgroups (Z = 4.35, P < 0.0009). These results point to a close relationship between apathy and the anterior cingulate region.

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PubMed2001

Space-time segmentation using level set active contours applied to myocardial gated SPECT.

This paper presents a new variational method for the segmentation of a moving object against a still background, over a sequence of [two-dimensional or three-dimensional (3-D)] image frames. The method is illustrated in application to myocardial gated single photon emission computed tomography (SPECT) data, and incorporates a level set framework to handle topological changes while providing closed boundaries. The key innovation is the introduction of a geometrical constraint into the derivation of the Euler-Lagrange equations, such that the segmentation of each individual frame can be interpreted as a closed boundary of an object (an isolevel of a set of hyper-surfaces) while integrating information over the entire sequence. This results in the definition of an evolution velocity normal to the object boundary. Applying this method to 3-D myocardial gated SPECT sequences, the left ventricle endocardial and epicardial limits can be computed in each frame. This space-time segmentation method was tested on simulated and clinical 3-D myocardial gated SPECT sequences and the corresponding ejection fractions were computed.

Algorithms↗

PubMed1999

Nonconvulsive status epilepticus of frontal origin.

OBJECTIVES: To determine the electroclinical characteristics and causative factors of nonconvulsive status epilepticus (NCSE) of frontal origin. METHODS: The authors conducted a 5-year prospective study. RESULTS: Ten patients were studied (seven men, three women; mean age, 56.4 years). Six patients did not have previous epilepsy. The mean diagnostic delay was 48 hours (range, 3 to 96 hours). Two types of frontal NCSE were identified. In type 1 (n = 7), mood disturbances with affective disinhibition or affective indifference were associated with subtle impairment of cognitive functions without overt confusion. EEG showed a unilateral frontal ictal pattern and normal background activity. In type 2 (n = 3), impaired consciousness was associated with bilateral, asymmetric frontal EEG discharges occurring on an abnormal background. Ictal and postictal 99mTc hexamethyl propylene amine oxime (HMPAO) SPECT was performed in five patients and showed unilateral or bilateral frontal HMPAO uptake that aided localization, especially in type 2 NCSE of frontal origin. Etiologies included a focal frontal lesion in six patients (three of which were tumors), neurosyphilis, and nonketotic hyperglycemia. Eight patients did not respond to initial IV benzodiazepine (BZ), but IV phenytoin controlled six patients successfully. The immediate outcome was favorable in all patients. There was no long-term recurrence of SE in seven patients. CONCLUSIONS: NCSE of frontal origin is a heterogeneous syndrome. Some cases are best described as simple partial NCSE, others as complex partial SE, and there are forms that overlap with absence SE. Emergency EEG and neuropsychological assessment are diagnostic, and SPECT may be useful. Many patients may not respond to IV BZ.

Adult↗

PubMed1999

Impact of attenuation correction by simultaneous emission/transmission tomography on visual assessment of 201Tl myocardial perfusion images.

UNLABELLED: It has been shown in clinical studies that for subjects with a low likelihood of coronary artery disease (CAD), attenuation correction (AC) improves the specificity of defect detection in the inferior wall (right coronary artery [RCA] region). The aim of this study was to investigate the effect of AC on the visual interpretation of the RCA and anteroseptal (corresponding to the left anterior descending artery [LAD]) regions in CAD patients. METHODS: Fifty-six patients with suspected CAD underwent 20Tl stress/4 h-delayed imaging SPECT using a simultaneous 201Tl emission/99mTc transmission imaging protocol. Images were reconstructed using the maximum likelihood-expectation maximum algorithm without and with AC. The stress/4 h-delayed images were interpreted blindly for reversible or fixed defects in the RCA and LAD regions by three experienced physicians. Coronary angiography, electrocardiography and enzyme findings were used to establish diagnoses of ischemia or infarction, and receiver operating characteristic (ROC) analyses were performed. RESULTS: Statistical testing of ROC curve areas showed that defect detection performance improved with AC when compared with performance without AC in the RCA region. This was mainly the result of a systematic increase in specificity of 12% or more (for any observer and any type of defect) for a similar sensitivity (no definite change in sensitivity values). However, defect detection performance significantly decreased in the LAD territory with AC images (P < 0.05) because of a systematic decrease in sensitivity of 20% or more, with no consistent change in specificity. Similar trends were observed when reversible and fixed defects were considered separately. CONCLUSION: AC significantly affects the visual interpretation of 201Tl stress/4 h-delayed SPECT images. This study confirmed the increase in specificity obtained with AC in the RCA territory. However, in the population considered, the studied AC was deleterious for the LAD territory assessment.

Coronary Disease↗

PubMed1998

Combined constraints for efficient algebraic regularized methods in fully 3D reconstruction.

SPECT systems incorporate the use of one or more rotating gamma cameras which can be equipped with cone-beam collimators to improve the trade-off between spatial resolution and sensitivity. The geometry of the cone-beam collimators implies that a specific 3D reconstruction algorithm must be applied. Algebraic methods provide the possibility of including the physical characteristics, such as attenuation, Compton scatter and detector response, in the reconstruction process. However, the reconstruction problem is an ill-posed problem which should be regularized. This paper presents a 3D algebraic method that combines three regularizing constraints. These constraints deal respectively with penalizing negative voxels, local noise smoothing and missing data compensation. The results presented were obtained from imaging simulations, phantom data and from a thyroid clinical study of a normal volunteer.

Algorithms↗

PubMed1995

A single photon emission computed tomography study of cerebral regional perfusion changes induced by a learning task in subjects with mild memory impairment.

Fifteen nondemented subjects with memory complaints underwent serial single photon emission computed tomography (SPECT) studies with technetium-99m-d, l-hexamethyl-propylene amine oxime (HMPAO) as tracer. Scans were carried out under a baseline conditions and during the learning phase of the Memory Efficiency Profile (MEP), a combined visual perception and memory task developed by Rey. Results indicate a positive correlation between activation, as indexed by HMPAO uptake, and neuropsychological assessment. Right temporal activation was correlated with MEP immediate recall. The right cerebellum was correlated with both MEP immediate and delayed recall. This study suggests that SPECT can show cortical activation during cognitive performance in subjects with mild memory impairment.

Aged↗

PubMed1995

Effect of pacing rate on regional left ventricular wall motion. Assessment by quantitative analysis of equilibrium radionuclide angiography.

We evaluated the hemodynamic impact of right ventricular pacing at different stimulation frequencies. Fourteen patients with a right ventricular pacemaker (VVI pacing with retrograde P wave) but without clinical and electrocardiographic evidence of coronary artery disease underwent two equilibrium radionuclide angiographies: one under low heart rate (50/60 beats per minute) and the other under fast heart rate (90/100 beats per minute). Left ventricular global and sectorial ejection fractions, amplitude and phase images of first harmonic, and sectorial phases of left ventricle were analyzed. In twelve patients (84.7%), sectorial ejection fraction abnormalities in the left ventricular apicoseptal and inferoapical regions were observed under low heart rate, and worsened under fast heart rate, while new onset sectorial ejection fraction abnormalities under fast heart rate were observed in the other two patients with normal sectorial ejection fraction under low heart rate. Sectorial ejection fractions of left ventricular apicoseptal and inferoapical regions significantly changed between low and high heart rate (- 14.1 +/- 3.8%, p < 0.005; - 7.5 +/- 2.4%, p < 0.01 respectively). Left ventricular sectorial phases were abnormal in only two patients (14.3%) under low heart rate, and in twelve patients (84.7%) under fast heart rate. Our study confirms that left ventricular regional wall motion abnormalities during VVI pacing significantly worsen under fast heart rate in comparison to those under low heart rate.

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PubMed1995

[Positron-emission tomography: role of 18F-fluorodeoxyglucose (18FDG) imaging in oncology].

There is a renewed interest in positron emission tomography (PET) using 18F-fluorodeoxyglucose (18FDG) since the development of large field of view cameras and the capability of regional distribution of 18FDG. This method may help solve three types of problems in clinical oncology: tumor diagnosis and extension assessment, prediction of treatment response and follow-up (diagnosis of recurrences and complications). The aim of this paper is to review the literature in this field. This technique is mostly used for brain, lung, rectal and breast tumors as well as for sarcomas. It is possible to diagnose an anaplastic transformation of a low grade glioma since 18FDG uptake correlates with the histological grade. 18FDG plays another important role in the evaluation of the brain tumor response to treatment and of the secondary effects or sequelae of this treatment. This technique is also useful in breast carcinomas: diagnosis in the case of a dense breast, detection of lymph nodes or other metastases which could modify the strategy. One of the most established roles of 18FDG PET is the diagnosis of rectal tumor recurrences. Furthermore, future results will probably confirm its usefulness in lung carcinoma, for the diagnosis and for treatment evaluation. Lastly, it plays an important role in soft tissue sarcomas at all stages of diagnosis and treatment. The results of the literature still have to be completed. However, if the capability of predicting tumor response to treatment is confirmed, this method will play an important role in patient management and will modify treatment strategies.

Cell Transformation, Neoplastic↗

PubMed1994

A radiolabelled iodobenzamide for malignant melanoma staging.

123I-N-(di-ethylamino-2-ethyl) 4 iodobenzamide (I-BZA) has been put forward by the Clermont-Ferrand INSERM U71 group (France) as a tracer for malignant melanoma. We report on the clinical results obtained in 56 studies performed on 48 patients. Whole body scans along with spot views were obtained after injection of 185 MBq of I-BZA. The scans were read by three independent observers and correlated to the clinical findings and the other imaging modalities available, taking into account all lesions larger than 1 cm. Patients were classified into two groups on the basis of a post-treatment survey of patients: group I, in complete remission (24 scans); group II: documented metastases (32 scans). In group 1, 21 studies were truly negative. However, three studies showed positive results. Only one turned out to be a false positive (specificity 95%), the other two revealed unknown lesions and modified the patients' management. In group II, 73% of the known metastases were detected with higher sensitivities (> 80%) for eye and orbit, lung and abdomen. One false positive was reported and four new lesions were detected. I-BZA scintigraphy has the same sensitivity as immunoscintigraphy with higher specificity and without the risk of xenoimmunization. It is a useful tool for staging malignant melanoma which can improve patient management.

Aged↗

PubMed1993

Cholescintigraphic study of effect of somatostatin analog, octreotide, on bile secretion and gallbladder emptying in normal subjects.

The objective of the study was to investigate the effects of a single intravenous injection of the somatostatin analog octreotide on hepatic bile secretion and gallbladder emptying with a quantitative scintigraphic technique. Twelve healthy volunteers received, in a double-blind randomized fashion, either octreotide, 100 micrograms intravenously, or placebo. Ten minutes later, [99mTc]PBIDA was administered intravenously (50 microCi/kg) (time = 0) followed, 60 min later, by the ingestion of a standardized fatty meal. In the liver area, the relative decrease per minute of tracer activity from the time of maximal activity to 60 min was significantly lower in the octreotide group (P = 0.02). In the gallbladder area, after the fatty meal, the ratio of tracer activity at 60 and 90 min (A90/A60) was significantly (P = 0.01) higher in the octreotide group. Our study demonstrates that octreotide slows down liver release of the radiopharmaceutical, probably reflecting decreased bile secretion, and inhibits postprandial gallbladder contraction.

Adult↗

PubMed1993

Nitrates improve detection of ischemic but viable myocardium by thallium-201 reinjection SPECT.

Thallium-201 reinjection imaging improves myocardial viability detection when compared to standard 3-4-hr redistribution imaging, however, the extent of ischemic but viable myocardium is still underestimated. We tested whether the sensitivity of reinjection imaging could be increased by giving nitrates postexercise to improve blood flow during the redistribution period. Twenty patients with coronary artery disease were included, 11 of them with a recent myocardial infarction. All patients underwent two exercise/4-hr redistribution 201Tl SPECT protocols: one with reinjection alone and the other with nitrates and reinjection. In the latter case, 20 mg of Isosorbide Dinitrate were given to patients immediately after postexercise imaging. Fifteen patients had reversible defects with reinjection alone, three additional patients were defined as ischemic with nitrates/reinjection protocol. Reinjection alone identified 41 reversible segmental defects, all except one were also evaluated as reversible with nitrates/reinjection. However, among the 54 segments showing fixed defects after reinjection only, 14 (26%) presented as reversible with the nitrates/reinjection protocol. The redistribution extent (segments/patient) was 2.05 +/- 0.41 segments with reinjection alone and 2.75 +/- 0.38 (p < 0.01) with nitrates/reinjection. In 15 patients showing reversible defects with both protocols, the redistribution extent was 2.73 +/- 0.41 segments with reinjection alone and 3.20 +/- 0.40 (p < 0.05) with nitrates/reinjection. Thallium-201 SPECT with nitrates and reinjection improves the detection of ischemic but viable myocardium in comparison to SPECT with reinjection alone.

Coronary Disease↗

PubMed1992

Correlations of left ventricular diastolic parameters and heart rate: assessment through right ventricular pacing.

This study evaluated the correlations between left ventricular (LV) diastolic parameters assessed by equilibrium radionuclide angiography (ERNA) and heart rate (HR) through right ventricular pacing. Twelve patients with a permanent right ventricular apex pace-maker were included. Serial ERNA studies were performed under 6 sets of pacing cycle length (heart rate = 52, 62, 72, 82, 92, 104 beats/min) for each patient. The left ventricular ejection fraction was 49.9% +/- 3.1% under pacing HR of 52 bpm and 43.8% +/- 3.1% under pacing HR of 104 bpm. The peak filling rate (PFR) increased very significantly with HR (r = 0.98, P less than 0.001). When the relative changes of end-diastolic volume were taken into account, the correlation between PFR and HR remained significant (r = 0.94, P less than 0.001). The absolute time to PFR (TPFR) did not significantly change with HR, but the ratio of TPFR to cycle length strongly correlated with HR. Our study clearly demonstrates that the PFR assessed by ERNA increases and the TPFR occupies an increasing proportion of the cycle length as HR increases. Therefore, LV diastolic parameters should be normalized for HR in clinical applications. In particular, HR changes should be considered when LV diastolic parameters are used for the assessment of therapeutic interventions.

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