Biomedical subjects

J Léveillé

Publications and source records attributed to J Léveillé.

At least 19 recordsLinked to original sources

PubMed2001

A severe frontal-parietal lobe syndrome following cerebellar damage.

We report a case study of a frontal and parietal lobe syndrome with memory loss after unilateral left-sided cerebellar damage caused by a stroke in a patient with right cerebellar unusual developmental agenesis. The syndrome consisted of severe deficits in planning an organized sequence of events, in visuo-constructive abilities and inappropriate jocularity. These changes are ascribed in part to cerebellar-pontine lesions with resulting frontal lobe diaschisis as documented by single-photon emission computed tomography in the absence of morphological damage to the neocortex.

Adult↗

PubMed1998

Idiopathic hypovolemia: a self-perpetuating autonomic dysfunction?

Unexplained episodic hypertension, hypotension, or orthostatic intolerance, tachycardia, anxiety, and flushing in 21 patients were investigated for the possibility of hypovolemia by blood volume and individual plasma catecholamines (including autocrine paracrine-born dopamine), determinations baseline, in response to upright posture and catecholamines only during the episodic blood pressure swings. Blood volume was determined by Cr51 fixed to patients' hemoglobin, free norepinephrine, epinephrine, and dopamine with dopamine sulfate following sulfatase hydrolysis, radioenzymatically. The recumbent mean 27.4+/-3% (SE) blood volume decrease from predicted values accentuating to 33.5+/-4% upright was associated with normal baseline plasma free norepinephrine, epinephrine, dopamine, dopamine sulfate, plasma renin activity, and aldosterone with normal mean postural responses from all patients except a hyperresponsive compared to controls (p < 0.04), plasma renin activity increase from 0.657+/-0.1 to 4.47+/-1.8 ng/mL/hr. During the hypertensive, hypotensive, or tachycardic episodes the moderate increase of free norepinephrine and epinephrine (p < 0.04) (but not free dopamine) contrasted with an increase of dopamine sulfate from 2.5+/-0.9 to clearly pathological values of 16.8+/-8.3 ng/mL (p < 0.0003 on % increase of individual values). We conclude that the normal (but to the degree of hypovolemia inappropriately low orthostatism- and episodes-associated sympathetic arousal) is outpaced by considerable episodic dopamine sulfate surges, reflecting extraneuronal dopamine discharge. Whether this increase contributes to the increased natriuresis directly or by inhibiting aldosterone response to renin-angiotensin, perpetuating hypovolemia, remains to be established.

Adolescent↗

PubMed1998

Metastatic axillary lymph node technetium-99m-MIBI imaging in primary breast cancer.

UNLABELLED: Technetium-99m-MIBI scintimammography has been shown to be useful in the detection of primary breast cancer. The purpose of this study was to evaluate the potential role of scintimammography in detecting axillary lymph node involvement in patients undergoing scintimammography to detect primary breast cancer. METHODS: A group of 100 women with breast cancer who were scheduled for a Level I-II axillary dissection were prospectively studied. Scintimammography was performed in all patients before histopathologic confirmation of breast cancer. Two lateral (prone imaging) views and one anterior (supine) planar thoracic view were obtained 10-15 min after the injection of 25-30 mCi 99mTc-MIBI (10 min/view) by using a special breast positioning device (foam cushion) placed over the imaging table. Both of the axilla were included in the field-of-view. Two experienced blinded observers reviewed all cases both from films and from the computer screen with contrast adjustment when needed. The site of intravenous injection of 99mTc-MIBI was known to the interpreters in order to avoid reading any false-positive uptake in the axilla ipsilateral to the injection site. RESULTS: A total of 52 patients had no axillary lymph node involvement (611 negative nodes) while 48 patients had at least one axillary lymph node with metastatic involvement (180/502 positive nodes). The sensitivity of scintimammography in detecting metastatic axillary lymph node involvement was 79.2% (38/48), and the specificity was 84.6% (44/52). The positive and the negative predictive values were 82.6% (38/46) and 81.5% (44/54), respectively. CONCLUSION: This study shows that scintimammography has good diagnostic accuracy for detecting axillary lymph node involvement in patients with breast cancer. This information should be added to the result of standard scintimammography, which requires very minor modifications in order to simultaneously evaluate both of the axilla.

Axilla↗

PubMed1995

Case study: dreamy state and temporal lobe dysfunction in a migrainous adolescent.

Symptoms of migraine can be very atypical during childhood and adolescence. This article describes a case in which the symptoms of migraine were mainly psychiatric: dreamy state, intermittent confusion, partial amnesia, and childlike regressive behavior with depressive features. Although the results from neurological examinations and electroencephalographic recordings were normal when the individual was symptomatic or not, temporal lobe dysfunction, determined by 99mTc-hexamethyl-propyleneamine oxamine single-photon emission computed tomography, was evident during the migraine.

Adolescent↗

PubMed1994

Neuropsychological functioning in unilateral cerebellar damage.

A woman had a left superior cerebellar artery infarct associated with reduced hexamethylpropileneamine oxime uptake on SPECT scan of the basal ganglia and frontoparietal areas of the opposite hemisphere performed poorly in some neuropsychological tests indicating right hemisphere dysfunction. There was a lengthening of reaction and movement times with the hand ipsilateral to the lesion. These deficits were temporary. A unilateral cerebellar lesion can produce neuropsychological deficits, possibly because of hypoperfusion in contralateral frontoparietal regions, but spontaneous neuropsychological remissions may occur.

Cerebellar Diseases↗

PubMed1994

The role of single photon emission computed tomography brain imaging with 99mTc-bicisate in the localization and definition of mechanism of ischemic stroke.

99mTc-bicisate (99mTc-ECD) is a new brain perfusion imaging agent formulated from a radiochemically stable kit (Neurolite). A multicenter trial was conducted to determine the sensitivity and specificity of single photon emission computed tomography (SPECT) imaging with 99mTc-bicisate in the localization of ischemic stroke; 170 subjects were enrolled, 128 patients with stroke and 42 controls. Imaging results from 148 subjects (107 stroke patients and 41 controls) were considered evaluable. In the evaluable subjects, SPECT brain imaging with 99mTc-bicisate (21.0 +/- 2.5 mCi) was interpreted without clinical information and was compared with a final assessment using all clinical, diagnostic, and laboratory procedures except the 99mTc-bicisate SPECT results. 99mTc-bicisate was safe and well-tolerated. SPECT imaging with 99mTc-bicisate demonstrated a specificity of 98% and a sensitivity of 86% for localization of strokes (kappa, 0.75; 95% confidence interval, 0.64-0.86). Results were unchanged over time and were similar for all stroke mechanisms except for lacunar disease (sensitivity, 58%). In a secondary analysis, a normal image or small, deep (e.g., subcortical) perfusion defect was highly predictive of a lacunar mechanism. Defects involving the cortical surface were strongly associated with nonlacunar mechanisms. SPECT imaging with 99mTc-bicisate is a sensitive marker in the localization of perfusion defects associated with ischemic stroke and may assist in the determination of the underlying mechanism of a stroke.

Adult↗

PubMed1992

Comparison between technetium-99m-teboroxime and thallium-201 dipyridamole planar myocardial perfusion imaging in detection of coronary artery disease.

Technetium-99m (TC-99m)-teboroxime is a new myocardial perfusion imaging agent. The purpose of this prospective study was to compare Tc-99m-teboroxime with thallium-201 imaging after the administration of dipyridamole. Thirty patients referred for the evaluation of chest pain were studied with both thallium-201 and Tc-99m-teboroxime dipyridamole scans (mean interval 2 days). Dipyridamole was administered at 0.142 mg/kg/min for 4 minutes. Planar imaging (3 standard views) was obtained at 5 and 240 minutes after the injection of 2.2 mCi of thallium-201. Tc-99m-teboroxime (18 to 25 mCi) was injected after dipyridamole infusion. A second injection, at rest, was repeated 4 hours later. Planar imaging (3 standard views of 1 minute/view for the first 2 views, and 90 seconds for the last view) was obtained 2 minutes after Tc-99m-teboroxime injection. Blinded reading was performed by 3 observers. Thallium-201 showed perfusion defects in 182 myocardial segments corresponding to 33 of 45 (73%) significantly stenosed coronary arteries (greater than or equal to 70% reduction in endoluminal diameter), and Tc-99m-teboroxime detected 160 abnormal segments corresponding to 29 of 45 (64%) stenosed arteries. Thallium-201 and Tc-99m-teboroxime studies were normal in 3 patients. In conclusion, this study shows that there is a good correlation in the imaging results found with thallium-201 and Tc-99m-teboroxime using dipyridamole infusion on both a segmental and a diagnostic comparison.

Adult↗

PubMed1992

In vivo measurement of atrial natriuretic peptide receptors using nuclear imaging.

We have successfully visualized atrial natriuretic peptide (ANP) receptors in vivo using nuclear imaging. 123I-Labelled ANP, injected in green vervet monkeys, was rapidly bound to ANP receptors in the kidneys and lungs. That the observed uptake was receptor mediated was demonstrated with competition studies using simultaneous injection of unlabelled ANP 99-126. It was possible to distinguish between the ANP receptor subtypes by the use of selective antagonists. Thus coinjection of ANP 102-121-des[Gln, Ser, Gly, Leu, Gly] (C-ANP), an ANP analog that selectively binds to the ANP C-receptor, decreased uptake in the kidneys by 50% but increased relative uptake in the lungs and soft tissues. This method permits for the first time, the dynamic in vivo analysis of ANP receptors and their interaction with endogenous ligand. Differences and changes in local ANP receptor concentrations and occupancy could be detected. Since ANP receptor density and affinity are influenced by various physiological and pathological conditions, clinical and diagnostic applications seem possible.

Animals↗

PubMed1992

Comparison between thallium-201, technetium-99m-sestamibi and technetium-99m-teboroxime planar myocardial perfusion imaging in detection of coronary artery disease.

Technetium-99m-sestamibi (MIBI) and 99mTc-teboroxime (TEBO) are two new myocardial perfusion imaging agents. The purpose of this prospective study was to compare MIBI and TEBO to 201TI planar imaging. Eighteen patients with significant coronary artery disease on coronary angiogram were submitted to three treadmill stress tests performed within 3 mo and were imaged with the three radiopharmaceuticals as follows. 1. TI: 2.2 mCi, immediate and delayed views (4 hr later, 8 min/view). 2. TEBO: 15-20 mCi at stress (1 min/view) and a second injection was repeated 4 hr later at rest (20-25 mCi). 3. MIBI: 15-18 mCi at stress (8 min/view) and 1-4 days later, 15-18 mCi at rest. Patients achieved similar levels of exercise. A blinded reading was performed by three observers. The left ventricle was divided into three segments/view and ischemic/normal wall ratios were also determined. Segmental comparison showed an agreement in 85% (138/162) of the segments between TI and TEBO, in 92% (149/162) between TI and MIBI and in 84% (136/162) between MIBI and TEBO. Abnormal TI, MIBI and TEBO studies were seen in 16 (89%), 16 (89%) and 15 (83%) patients, respectively, detecting 77, 75 and 65 abnormal segments. Ischemic-to-normal wall ratios were 0.75 +/- 0.06, 0.73 +/- 0.08 and 0.78 +/- 0.08 for TI, MIBI and TEBO, respectively. In conclusion, although the biologic characteristics of these agents are different, this study showed a good correlation between them in detection of significant coronary artery disease (high pretest likelihood population).

Aged↗

PubMed1992

Intrasubject comparison between technetium-99m-ECD and technetium-99m-HMPAO in healthy human subjects.

The pharmacokinetics and quality of planar and SPECT brain imaging of two 99mTc-labeled brain perfusion agents, d,l-hexamethyl propylene amine oxime (HMPAO) and ethyl cysteinate dimer (ECD), were compared in seven healthy, normal subjects. Both radiopharmaceuticals showed rapid brain uptake and had a net brain washout of less than 5% during the first 20 min after drug administration. However, during the same time period, 99mTc-ECD images of the head showed significantly less background facial uptake and retention when compared to 99mTc-HMPAO images. The brain-to-background contrast ratio of 99mTc-ECD (brain/neck) continued to improve over time and by 5 hr postadministration was 17 to 1 versus 2 to 1 for 99mTc-HMPAO. SPECT brain images of both agents show gray/white matter ratios that were unchanged over time and an intracerebral distribution consistent with blood flow. A blind read of these SPECT images also shows 99mTc-ECD to produce images that were "easier to interpret" with less extracerebral activity as compared to 99mTc-HMPAO. Repeat, whole-body planar spot imaging suggests that 99mTc-ECD was cleared more rapidly from the body than was 99mTc-HMPAO.

Adult↗

PubMed1991

Single photon emission computed tomography (SPECT) in cerebellar disease: cerebello-cerebral diaschisis.

Single photon emission computed tomography assessments were conducted in normal controls (n = 25), patients with unilateral cerebellar infarctions (n = 4), patients with olivopontocerebellar atrophy (OPCA; n = 15) and patients with Friedreich's ataxia (FA; n = 6). In subjects with unilateral cerebellar infarctions, crossed cerebellar-cortical diaschisis was observed: reduced cerebellar hexamethylpropyleneamine oxime (HMPAO) uptake was invariably accompanied by a diminution of HMPAO in the contralateral basal ganglia and frontoparietal cortex. OPCA and FA patients had various degrees of decreased HMPAO uptake in both the cerebellum and cerebral hemispheres.

Adult↗

PubMed1991

Technetium-99m-sestamibi myocardial perfusion imaging in detection of coronary artery disease: comparison between initial (1-hour) and delayed (3-hour) postexercise images.

Technetium-99m-sestamibi, a new myocardial perfusion imaging agent, does not show significant or rapid myocardial redistribution following its intravenous injection at stress. The purpose of this study was to evaluate the myocardial clearance of 99mTc-sestamibi and ischemic/normal wall ratios at 1 hr and at 3 hr after injection at stress in patients with significant coronary artery disease. Twenty-five patients with ischemic defects on 201Tl scans (n = 15) and/or significant disease on coronary angiogram (n = 18) were prospectively studied. Planar images were obtained at 65 and at 190 min after an injection at stress of 20-25 mCi of 99mTc-sestamibi. A rest study was performed 1-6 days later. Ischemic/normal wall ratios were 0.73 +/- 0.10 and 0.83 +/- 0.12 (p less than 0.05) at 1 and 3 hr, respectively (0.98 +/- 0.15 at rest). Myocardial washout was 26% +/- 12% for normal walls and 15% +/- 8% for ischemic walls (p less than 0.001). Segmental analysis showed 48 and 46 ischemic segments at 1 and 3 hr, respectively. In conclusion, although only a few ischemic segments were missed at 3 hr, significantly lower ischemic/normal wall ratios were found at 1 hr. Faster myocardial washout from normal walls is responsible for the partial reduction of this ratio.

Coronary Disease↗

PubMed1989

Same day injections of Tc-99m methoxy isobutyl isonitrile (hexamibi) for myocardial tomographic imaging: comparison between rest-stress and stress-rest injection sequences.

It has been shown that both rest and stress 99mTc-hexamibi myocardial perfusion imaging can be performed on the same day using two different doses injected within few hours (the first one at rest followed by a second at stress). In order to evaluate and compare 2 sequences (rest-stress and stress-rest) of 99mTc-hexamibi injections performed the same day, 18 patients with either abnormal 201Tl myocardial scan or abnormal coronary angiography were studied with 2 99mTc-hexamibi injections protocols. The rest-stress study was performed as follows: 7 mCi 99mTc-hexamibi was injected at rest. Single photon emission computed tomography (SPECT) was performed 60 min later. Immediately after the rest study, patients were injected at peak stress with 25 mCi 99mTc-hexamibi. Tomographic imaging was repeated 1 h later. Patients were submitted to the stress-rest protocol within 3 days. Tomographic imaging was done 1 h after a 7 mCi injection at stress. This study was followed by an injection of 25 mCi 99mTc-hexamibi at rest, a tomographic study was performed 60 min later. Myocardial sections were reconstructed in horizontal long, vertical long, and short axes. Data analysis also included polar map representation. A total of 324 segments were interpreted blind by 3 observers, there was an agreement in 283/324 (87.3%) segments between the 2 protocols. However, 24 segments (7.4%) judged ischemic on rest-stress were called scars on stress-rest.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Clinical comparison between thallium-201 and Tc-99m-methoxy isobutyl isonitrile (hexamibi) myocardial perfusion imaging for detection of coronary artery disease.

99mTc-hexamibi (methoxy isobutyl isonitrile) is a new 99mTc-hexakis analog that can be used as a myocardial perfusion imaging agent. The purposes of this study were to compare 99mTc-hexamibi to 201Tl-thallous chloride myocardial stress scintigraphy in patients referred for investigation of chest pain and to evaluate the sensitivity of 99mTc-hexamibi in detection of coronary artery disease. One hundred patients were prospectively studied with both 201Tl and 99mTc-hexamibi planar imaging. Sixty five patients had a current coronary angiography. There was a total of 97 significantly (less than or equal to 70%) stenosed major coronary arteries. 99mTc-hexamibi (25 mCi) study was done within a week of the 201Tl scan with similar double products upon standard treadmil stress testing. Rest studies with 99mTc-hexamibi were obtained 24-48 h after the stress test using the same acquisition parameters and dose. Analysis was performed blind by three observers. The left ventricle was divided into five segments in each image. Analysis of 201Tl and 99mTc-hexamibi results in 1500 left ventricle segments showed an overall agreement in 1326/1500 (88.4%) segments. Correlation between the patient diagnosis on the 201Tl and 99mTc-hexamibi studies showed an agreement in 89 patients (89%). 201Tl revealed myocardial uptake defects in 526 segments, detecting 72 out of 97 (74.2%) significantly stenosed coronary arteries and 99mTc-hexamibi detected 513 segments corresponding to 68 (70.1%) stenosed arteries (no significant statistical difference). In conclusion, these results show a good correlation between 201Tl and 99mTc-hexamibi myocardial imaging in the detection of significant coronary artery disease.

Adult↗

PubMed1989

Characterization of technetium-99m-L,L-ECD for brain perfusion imaging, Part 2: Biodistribution and brain imaging in humans.

The safety, biodistribution and kinetics of a new perfusion imaging agent [99mTc-L,L]-ethyl cysteinate dimer (ECD) was evaluated in normal volunteers. Technetium-99m-L,L-ECD is a neutral, lipophilic complex, which is radiochemically pure and stable. Twelve healthy adults were injected with 25-30 mCi of 99mTc-L,L-ECD and imaged periodically for up to 24 hr. Planar imaging showed rapid brain uptake with a peak concentration of 4.9% injected dose and very slow brain washout (approximately 6% per hour during the first 6 hr). Repeat or dynamic tomographic imaging of the brain using either a rotating gamma camera or a multidetector system was performed up to 6 hr postinjection. The distribution of 99mTc-L,L-ECD in the brain did not change and was similar to the pattern seen with other perfusion agents. Background facial areas and lungs cleared rapidly. Peak blood activity was below 10% injected dose at all times and 99mTc-L,L-ECD cleared rapidly through the kidneys. Vital signs, blood and urine chemistries were normal in all volunteers and no adverse reactions were noted. These results suggest that 99mTc-L,L-ECD should be useful for routine assessment of cerebral perfusion in humans.

Adult↗

PubMed1988

Myocardial perfusion imaging with 99mTc-methoxy-isobutyl-isonitrile (MIBI): comparison of short and long time intervals between rest and stress injections. Preliminary results.

Unlike 201Tl, 99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI) does not redistribute in the myocardium after injection. Thus, two separate injections of this new myocardial perfusion agent are required to differentiate ischemia from scar. An injection at stress followed by a 2nd injection at rest performed 24 h later, or the inverse, has been proposed. This protocol is not ideal in clinical practice. It would be preferred if both injections were performed on the same day. Fifteen patients with significant coronary artery disease demonstrated by coronary angiography and with at least one ischemic segment on the myocardial 201Tl study were evaluated within two weeks with the following protocol. On the same day (short time interval protocol), 3 images, each of 10 min duration (anterior, 45 degrees LAO and 70 degrees LAO views) were performed between 30 to 60 min after the injection at rest of 7-10 mCi 99mTc-MIBI. On completion of the rest study, the patient received 25-30 mCi 99mTc-MIBI at stress and images were again obtained 30 to 60 min later. Two days later (long time interval protocol) a stress study alone was repeated using 10 mCi 99mTc-MIBI with the same imaging time. Qualitative and quantitative comparisons between the short and the long time interval studies were performed by four experienced observers. Both protocols showed the same number of ischemic segments (52/225) and fixed defects (19/225). The diagnostic information of images was judged similar in nine patients while the short protocol was judged superior to the long protocol in five patients and inferior in 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

A reproducible radionuclide procedure for measurement of cerebrospinal fluid shunt flow.

A radionuclide technique was developed to obtain reproducible measurements of cerebrospinal fluid flow in Rickham-Holter type shunt systems. In attempting to reproduce previously described radionuclide procedures, we found that different flow rate measurements can be obtained simply by changing the radiotracer injection technique or the method of analysis of the time activity curves which are generated. The importance of these technical pitfalls cannot be over-emphasized, since there is no gold standard to evaluate cerebrospinal fluid flow in vivo. An experimental model with a calibrated Harvard pump and a shunt system filled with normal saline was constructed. Aliquots of 500 microCi of pertechnetate in 0.05 ml of saline were injected serially into the center of Rickham reservoir using a size 28 needle. Time-activity curves were obtained after waiting five min to reach equilibrium, and standard curves of radiotracer clearance vs actual flow for each system used clinically in our institution were generated. In addition, a technique to quantify and thus correct for the small but significant leak of radiotracer which occurs at the site of injection in the reservoir is described. Excellent correlation was obtained between our results and the clinical and radiological findings in a preliminary clinical evaluation.

Cerebrospinal Fluid↗

PubMed1986

Thallium-201 myocardial imaging during pharmacologic coronary vasodilation: comparison of oral and intravenous administration of dipyridamole.

Although the diagnostic utility of thallium-201 myocardial imaging after dipyridamole infusion is well established, the intravenous form of the drug is not yet commercially available in North America. Fifty patients referred for coronary angiography were prospectively studied. Within a 2 week period, each patient underwent cardiac catheterization and thallium-201 myocardial imaging after both oral and intravenous dipyridamole administration. For the oral protocol, patients were randomly assigned to treatment with either 200 or 400 mg of dipyridamole in tablet form. Coronary artery stenoses of 70% or greater were considered significant. For the 25 patients who received a 200 mg oral dose of dipyridamole, the scintigraphic study showed perfusion defects in 65% of patients with significant coronary artery disease after the oral dose and in 85% of patients after the intravenous dose. For the 25 patients who received a 400 mg oral dose, the sensitivity of the scintigram was 84% after the oral dose and 79% after the intravenous dose. Except for headache and nausea, side effects were less severe and less frequent with oral (either 200 or 400 mg) than with intravenous dipyridamole. Because of the delayed and variable absorption of dipyridamole tablets, the oral studies required a longer period of medical supervision (45 to 60 minutes), and aminophylline was empirically administered after completion of the first set of thallium-201 images. It is concluded from this study that thallium-201 myocardial imaging after coronary vasodilation with a 400 mg oral dose of dipyridamole is a safe, widely available and reliable alternative for the evaluation of coronary artery disease in patients unable to achieve an adequate exercise level on stress testing.

Administration, Oral↗