[Contribution of lymphoscintigraphy in the exploration of lymphedema in children]

OBJECTIVES

The objectives of this work were a) to assess the feasibility of lymphoscintigraphy in very young children, and b) to assess its usefulness in understanding the underlying pathophysiology.

PATIENTS AND METHODS

Forty-one children (age range 3 months-16 years) with primary lymphedema of the lower and/or upper limbs underwent lymphosinctigraphy using 99mTC-labeled colloid (Nanocis or Nanocol) injected subcutaneous at the foot and/or hand level. Recording time, which depended on the child's age, included at least static images during the thirty minutes following injection and four hours later.

RESULTS

Abnormal activity of the lymph collectors, nodes, and interstitial space were analyzed according to age (> or < 2 years). Abnormal findings were classed as simple hypoplasia (n=18) or other type of lymph disease: diffuse lymphatic dysplasia (n=6), mixed vascular dysmorphism (n=5), amniotic bride disease (n=1), and hypoplasia revealed by occurrence of a minor factor (n=11). These observations demonstrate the role of lymphoscintigraphy in the diagnosis and prognostic evaluation of lymphedema in children.

CONCLUSION

Lymphoscintigraphy is a useful technique for very young children with lymphedema providing further information contributing to overall exploration.

The value of immunoscintigraphy in the detection of recurrent colorectal cancer

The aim of this prospective study was to determine whether anti-carcinoembryonic antigen (anti-CEA) scintigraphy is a useful additional technique in the diagnosis recurrence of colorectal cancer. Forty patients with suspected recurrence of colorectal cancer, underwent immunoscintigraphy (IS) and helical computed tomography (CT) in the 2 weeks before surgery. Surgical findings were used to evaluate the performance of the imaging techniques. Suspected areas on IS and CT were systematically explored. Helical CT was found to be superior to IS for the liver, the sensitivity and specificity of CT being 100% and 90%, respectively, vs 53% and 100% for IS. However, IS was better than CT for the detection of extra-hepatic abdominal recurrence: sensitivity and specificity of IS were 100 and 82% respectively vs 33 and 82% for CT. Seven cases of peritoneal carcinomatosis were overlooked by helical CT. Our results indicate that IS improves detection of extra-hepatic abdominal recurrence of colorectal cancer. Immunoscintigraphy is valuable as a guide to the treatment strategy and operative procedures.

Quantitative analysis of striatal dopamine D2 receptors with 123 I-iodolisuride SPECT in degenerative extrapyramidal diseases

123I-Iodolisuride has high specific affinity for binding on dopamine D2 receptors in the striatum and has been used in a few single photon emission computed tomography (SPECT) studies of extrapyramidal disorders. The diagnosis of Parkinson's disease (PD) is very difficult in the first 5 years of evolution, with 15-25% false positive diagnoses. The aim of this study was therefore to determine the value of iodolisuride SPECT in discriminating Parkinson's from the most frequent Parkinson-plus syndromes (PPS). Seventeen patients with an extrapyramidal syndrome had a SPECT examination 1 h after injection of 180-185 MBq of 123I-iodolisuride. They were followed under dopaminergic treatment for at least 2 years. After 2 years, they were separated in two groups according to specific clinical criteria and sensitivity to dopaminergic treatment: nine patients had PD (age = 59.8+/-8.8 years; Hoehn and Yahr = 1.8+/-0.7; evolution = 4.3+/-3 years) and eight had PPS (age = 71.6+/-7.3 years; Hoehn and Yahr = 2.9+/-2.0; evolution = 4.1+/-1.5 years). The binding potential of iodolisuride in the striatum was assessed by considering the striatum (S)/occipital lobe (O) ratio at the pseudo-equilibrium 1 h after injection. The S/O ratio was statistically different between PD and PPS (1.97+/-0.3 vs. 1.65+/-0.2 (P<0.02)). Iodolisuride SPECT could differentiate both groups with a sensitivity of 88.8% and a specificity of 75%. Iodolisuride is a good specific D2 receptor ligand for SPECT and complements specific clinical criteria for the diagnosis of Parkinson's disease and differentiation between different extrapyramidal disorders.

Characterization of 99mTc-DTPA aerosols for lung permeability studies

BACKGROUND

The interpretation of 99mTc diethylenetriamine pentaacetate (99mTc DTPA) aerosol clearance is based on the hypothesis that the 99mTc-DTPA complex is not altered by the nebulization process.

OBJECTIVES

To characterize (1) the radiochemical purity (RCP) of 99mTc-DTPA and the stability of labeling after jet nebulization, and (2) the particle size distribution of the aerosol.

METHODS

RCP and stability--the aerosol was driven by oxygen, captured on filters which were eluted and RCP was checked by thin layer chromatography. Particle size distribution--the aerosol was generated using dry air (50 psi) at three different flow rates, i.e. 3 (1 run), 6 (4 runs) and 9 l x min(-1) (4 runs). The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (sigma(g)) were determined using a cascade impactor from the radioactivity counted on each stage.

RESULTS

The RCP was more than 95% in all cases. Mean MMAD (+/-SD) was 0.70 microm (+/-0.07) at 9 l x min(-1), 0.93 microm (+/-0.05) at 6 l x min(-1) (p < 0.05) and 1.50 microm at 3 l x min(-1). Mean sigma(g) (+/-SD) was 2.02 (+/-0.08) at 9 l x min(-1), 2.00 (+/-0.16) at 6 l x min(-1) and 1.90 at 3 l x min(-1).

CONCLUSION

This study demonstrates (1) that the high RCP of 99mTc-DTPA is not affected by jet nebulization, even when using oxygen at a high flow rate, and (2) that when using a flow rate between 6 and 9 l x min(-1), the MMAD remains optimal for peripheral lung deposition.

Technetium-99m ECD single photon emission computed tomography in brain trauma: comparison of early scintigraphic findings with long-term neuropsychological outcome

OBJECTIVE

The aim of this study was to assess the prognostic value of early brain scintigraphy in head injury in relation to long-term neuropsychological behavior. Twenty-four patients underwent technetium-99m (Tc-99m) ethyl cysteinate dimer single photon emission computed tomography (SPECT) within 1 month of the trauma. Scintigraphic abnormalities were evaluated both visually and semiquantitatively using the brain-to-cerebellum ratio method. The clinical neuropsychological investigation was conducted to evaluate abnormalities related to motor deficit, frontal behavior, and memory and language disorders. All patients had abnormalities on SPECT scan. One year after trauma, 14 patients (58%) had neuropsychological sequelae. The brain-to-cerebellum ratios in the left basal ganglia and brain stem were significantly decreased in patients with memory disorders (P = .03 and P = .02, respectively). Moreover, SPECT visual analysis indicated that low uptake in the basal ganglia, thalamus, and brain stem was associated with subsequent motor deficit, frontal behavior, and language and memory disorders. The authors conclude that brain SPECT can be valuable in predicting the neuropsychological behavior of survivors of severe head injury.

D2 receptor imaging in neonates using I-123 iodobenzamide brain SPECT

PURPOSE

Hypoxic-ischemic injury induces early changes in cerebral energy that later lead to the presence and extension of brain damage and subsequently to severe neurodevelopmental impairments such as the dyskinetic form of cerebral palsy, which is associated with damage to the striatum. The purpose of the current study was to evaluate the viability of D2 receptors in the perinatal period using I-123 iodobenzamide brain SPECT and to correlate this with early neurologic status.

METHODS

After obtaining informed parental consent, 12 full-term neonates with hypoxic-ischemic events were included. I-123 iodobenzamide brain SPECT was performed 1 week after birth, corresponding to a gestational age of 39.2+/-1.7 weeks. Images were acquired using a brain-dedicated gamma camera 1 hour after intravenous injection of 30 MBq (0.8 mCi) I-123 iodobenzamide. Magnetic resonance images (T2 weighted sequence: repetition time/echo time: 2,000/30 to 150) of the brains of the same neonates were acquired on the same day.

RESULTS

The right and left striatum:cerebellum activity ratios were between 1.28 and 2.25, with the greatest concentration of I-123 iodobenzamide occurring in the striatum area. A tendency of the striatum:cerebellum ratio to decrease was observed as the severity of the perinatal hypoxic-ischemic event increased despite striatal hypersignal on magnetic resonance imaging in only two neonates.

CONCLUSIONS

This study, which confirms that I-123 iodobenzamide could be used in the neonatal period, shows the biochemical maturation of D2 receptors as early as 1 week after birth and also suggests the deleterious effect of perinatal hypoxic-ischemic events on D2 receptors.

[Amyotrophic lateral sclerosis manifesting as cognitive disorders. Value of brain perfusion scintigraphic tomography in intensive care]

BACKGROUND

Cognitive disorders have been described in amyotrophic lateral sclerosis, but usually after the diagnosis has ben established.

CASE REPORT

A 57-year-old man was intubated for acute respiratory distress subsequent to pneumonia and diaphragm palsy. He had a 2-year history of drug-resistant depression and deterioration of cognitive functions. A pyramidal syndrome associated with biopsy-proven chronic neurogenic atrophy led to the diagnosis of amyotrophic lateral sclerosis. The electromyogram did not contribute to diagnosis. Brain MRI only evidenced moderate bilateral frontal-temporal atrophy. Brain SPECT demonstrated major perfusion defects in the frontal lobes.

DISCUSSION

This patient had amyotrophic lateral sclerosis and frontal-temporal dementia with an unusually late onset clinical presentation: cognitive disorder was the inaugural sign. Brain SPECT and muscle biopsy enabled us to identify the cortical and peripheral motor neurone involvement in this uncooperative intensive care patient totally dependent on mechanical ventilation.

Effects of the method of drawing regions of interest on the differential diagnosis of extrapyramidal syndromes using 123I-iodolisuride SPET

Various parameters are currently used for the semi-quantitative assessment of dopamine D2 receptors and differ according to the delineation of the striatal region of interest (ROI) and the choice of the reference ROI. The aim of this study was to assess the value of different ROI approaches in differentiating patients with normal or increased numbers of D2 dopamine receptors (group 1 = Parkinson's disease, n = 8) from patients with decreased dopamine D2 receptors (group 2 = other extrapyramidal syndromes, n = 9) using 123I-iodolisuride SPET (ILIS-SPET). 123I-iodolisuride (190 +/- 31 MBq) and 99Tcm-ethyl cysteinate dimer (99Tcm-ECD) perfusion SPET were performed in the same position, with a dual-headed gamera camera equipped with fan beam collimators. Both a geometric approach (ellipse, circle or rectangle) and an anatomical approach using the CT scan and perfusion SPET as anatomical guides were used to draw striatal and reference ROIs. A total of 33 different parameters were calculated for each patient, indicating the ratio of counts between the striatal and reference ROIs (frontal, occipital cortex or cerebellum) and the asymmetry between the right and left striatum. More significant differences between group 1 and group 2 were found by using geometric ROIs than by using anatomical ROIs. The most discriminant ratios were the caudate/occipital, caudate/frontal and striatum/occipital ratios (P = 0.001, P = 0.002, P = 0.003 respectively). A close correlation was found between the striatum/caudate and striatum/occipital ratios, but not between the striatum/frontal and striatum/occipital ratios or between the striatum/frontal and striatum/caudate ratios. We conclude that the occipital cortex is the best reference for the semi-quantitative evaluation of dopamine D2 receptors as the frontal cortex could include some dopamine D2 receptor-bound radioligand, and that the caudate/occipital ratio is an appropriate parameter for differentiating Parkinson's disease from non-Parkinson extrapyramidal syndrome by 123I-iodolisuride SPET.

[Scintigraphic imaging of stage III non-small-cell bronchial cancer]

Scintigraphic imagery is a functional image based on the difference of the in vivo concentration of injected radio-active traces as a function-of the metabolic characteristics of the tissues. A positive emission tomography (TEP) relies on an injection of substances which reflect the metabolic activity of the tissues and consist of protein renewal with 11C-methionine or glucose metabolism with F18-fluorodeoxyglucose (FTG). The imagery by TEP enables 85-90% of solitary pulmonary nodules to be detected. The degree of capture of the tracer enables some differentiation of a malignant lesion from a benign lesion which fixes less. In the assessment of the degree of extension in the mediastinal nodes of non-small cell Stage III cancers imagery by TEP has a sensitivity ads specificity which appears superior to those of computed tomography (TEM). The interpretation of the image is simplified by carrying out fusion images between TEM and TEP. The application of TEP in the research into thoracic recurrence has shown a cumulated specificity of 81% and a reliability of 91%. The imagery by TEP is only practised in a few centres. It should be developed in pulmonary pathology if the cost of the apparatus diminishes and if FTG is available. Radioscintigraphy is losing ground in the precise domain of non-small cell carcinoma although it shows up well as a technique in neuro-endocrine tumours. Few studies have shown a decisive value in the radioimmunoscintigraphic evaluation of the extension of mediastinal nodes. A gallium 67 scintigraphy has weak specificity and on account of this has been abandoned for the staging of tumours. Another approach has been isotopic imagery of macrophages but is major inconvenience is a lack of specificity. Scintigraphic studies coupled with ventilation/perfusion remains a useful pre-operative test above all in patients with chronic airflow obstruction with gross tumours at the borderline of operability.

Exploration of the dopamine transporter: in vitro and in vivo characterization of a high-affinity and high-specificity iodinated tropane derivative (E)-N-(3-iodoprop-2-enyl)-2beta-carbomethoxy-3beta-(4'-m ethylph enyl)nortropane (PE2I)

For the diagnosis and follow-up of neurodegenerative diseases, many cocaine derivatives have been proposed as radioligands to explore the dopamine transporter. As none of them have all the criteria of specificity and kinetics for human use, we have developed a new derivative, (E)-N-(3-iodoprop-2-enyl)-2beta-carbomethoxy-3beta-(4'-methy lphenyl)nortropane (PE2I), which displays promising properties. We report the characterization of PE2I in vitro on rat striatal membranes and in vivo in rats and in monkeys. PE2I had a high affinity (Kd = 0.09 +/- 0.01 nM) and high specificity for the dopamine transporter. In rats we observed a high accumulation in the striatum; by contrast, a very low fixation was measured in the cortex. Moreover, a preinjection of a saturating dose of GBR 12909 prevented the striatal accumulation of PE2I by 74%. These results confirmed the specificity of PE2I for the dopamine transporter. In vivo in monkeys, SPECT studies showed a high accumulation in striatum. Moreover, an equilibrium state was obtained 1 h after injection. PE2I seemed to be the most promising ligand for the dopamine transporter exploration by SPECT using a single-day protocol.

Pharmacokinetics and dosimetry of iodine-123 labelled PE2I in humans, a radioligand for dopamine transporter imaging

The iodine-123 labelled selective ligand N-(3-iodoprop-2E-enyl)-2-beta-carbomethoxy-3beta-(4-methylphenyl) nortropane ([123I]PE2I) was evaluated as a probe for in vivo dopamine transporter imaging in the human brain. Six healthy subjects were imaged with a high-resolution single-photon emission tomography scanner. Striatal radioactivity peaked at 1 h after injection. The background radioactivity was low. The volume of distribution in the striatum was 94+/-24 ml/ml. The results were compared with those of [123I]beta-CIT imaging. There was no significant uptake of [123I]PE2I in serotonin-rich regions such as the midbrain, hypothalamus and anterior gingulus, suggesting that in vivo binding is specific for the dopamine transporter. One main polar metabolite of [123I]PE2I was found in plasma, and the parent plasma concentration decayed rapidly. Radiation exposure to the study subject is 0.022+/-0.004 mSv/MBq (effective dose). The preliminary results suggest that [123I]PE2I is a selective SPET ligand for imaging striatal dopamine transporter density.

A new iodinated tropane derivative (beta-CDIT) for in vivo dopamine transporter exploration: comparison with beta-CIT

SPECT exploration of the dopamine transporter with tropane derivatives such as beta-CIT has already produced very valuable information in humans. However, the high affinity of this tracer for both dopamine and serotonin transporters and its slow in vivo kinetics provide the best images in humans more than 20 h after injection. In order to improve those properties, we performed structural changes in the tropane structure in the phenyl and nitrogen substituents for higher affinity and specificity and obtained a promising ligand, 2 beta-carbomethoxy-3 beta-(3',4' diclorophenyl)-8-(3-iodoprop-2E-enyl) nortropane (beta-CDIT). This iodinated ligand was characterized in vitro and in vivo in the rat in comparison with beta-CIT. In vitro competition studies revealed that beta-CIT and beta-CDIT similarly inhibited the binding of [3H]GBR 12935 (Ki = 27.5 and 29.0 nM, respectively). In contrast, competition studies with [3H]paroxetine and [3H]nisoxetine showed that beta-CDIT had a lower affinity for the serotonin transporter than beta-CIT (Ki = 50 and 3 nM, respectively) and also a lower affinity for the noradrenaline transporter than beta-CIT (Ki = 500 and 80 nM, respectively). In vivo studies in the rat showed that there was high and rapid uptake of [125I] beta-CDIT in the striatum. In addition, preinjection of GBR 12909 prevented accumulation of this ligand in the striatum by 80%, whereas only a 30% decrease was obtained for [125I] beta-CIT. It seems, therefore, that the combination of aromatic and nitrogen substitution improves the properties of tropane derivatives to provide an exclusive dopamine transporter ligand potentially usable in SPECT.

Iodolisuride and iodobenzamide, two ligands for SPECT exploration of the dopaminergic D2 receptors: a comparative study

Iodobenzamide (IBZM) and iodolisuride (ILIS), which belong to different chemical families, are two radioligands used for SPECT imaging of dopamine D2 receptors. We have compared their cerebral biodistribution in control rats and their ability to detect quantitative modifications of D2 receptors in experimental models. IBZM and ILIS have a similar cerebral distribution in vivo in control rats and permitted the detection of upregulation of striatal dopamine D2 receptors in a model of chronic haloperidol treatment. Moreover, we observed that 1 h after injection of a saturating dose of haloperidol, IBZM uptake was 72% displaced from the striatum, while ILIS uptake was 50% displaced. In an experimental model of excitotoxic striatal lesion, the in vivo accumulation of IBZM was 30% decreased on the lesioned side, in agreement with a decrease in dopamine D2 receptor density. By contrast, the accumulation of ILIS was identical in the lesioned and in the intact striatum. From the results, it appears that IBZM and ILIS, which are both used to image dopamine D2 receptors in vivo, behave differently in pathological experimental models. The ligand for human exploration should then be chosen according to the suspected pathology.

Iododerivative of pargyline: a potential tracer for the exploration of monoamine oxidase sites by SPECT

Monoamine oxidases are important in the regulation of monoaminergic neurotransmission. An increase in monoamine oxidase B (MAO B) has been observed in some neurodegenerative diseases, and therefore quantification of cerebral MAO B activity by SPECT would be useful for the diagnosis and therapeutic follow-up of these disorders. We have developed an iodinated derivative of pargyline, a selective inhibitor of MAO B, in order to explore this enzyme by SPECT. Stable bromo and iodo derivatives of pargyline were synthesized and chemically characterized. The radioiodinated ligand [125I]-2-iodopargyline was obtained with high specific activity from the bromo precursor by nucleophilic exchange. Affinity and selectivity of 2-iodopargyline were tested in vitro. Biodistribution study of [125I]-2-iodopargyline was performed in rats. Radioiodinated ligand were obtained in a no-carrier-added form. 2-iodopargyline has a higher in vitro affinity for MAO B than pargyline. However, the in vitro selectivity for MAO B was better for pargyline than for 2-iodopargyline. Ex vivo autoradiographic studies and in vivo saturation studies with selective inhibitors of MAO showed that the cerebral biodistribution of [125I]-2-iodopargyline in the rat is consistent with high level binding to MAO B sites in the pineal gland and in the thalamus. In conclusion, 2-iodopargyline preferentially binds in vivo to MAO B sites with high affinity. However, its selectivity for MAO B in rats is not very high, whereas this ligand binds to a lesser extent to MAO A. It will be then of great value to evaluate the specificity of 2-iodopargyline in humans. This new ligand labeled with 123I should therefore be a suitable tool for SPECT exploration of MAO B in the human brain.

[Tracheal carcinoma infiltrating the thyroid gland and mimicking subacute thyroiditis. Contribution of Doppler to differential diagnosis]

In the present case Color Coded Doppler showed a marked increase in vascularization in the right lobe of the thyroid with high systolic velocities (1 m/s). This sign was only doubtful compared with clinical, biological and isotopic data. Because of dramatic laryngeal dyspnea, surgery was conducted which allowed the final diagnosis of thyroid invasion by tracheal epidermoid carcinoma. This demonstrates the particular role of Color Coded Doppler in the management of inflammatory thyroid diseases.

[Progressive supranuclear paralysis. Quantification of dopamine D2 receptors using radionuclide tomography]

Progressive supranuclear palsy (PSP) may sometimes be misdiagnosed as Parkinson's disease in its early stages, hence an early positive diagnosis of PSP based on dopamine D2 receptor density could be extremely valuable. In the present case report, the absence of dopamine D2 receptors was clearly demonstrated in the striatum using 123I-iodobenzamide (IBZM) tomoscintigraphy. This illustrates the potential use of IBZM tomoscintigraphy to identify Parkinson-like's disease presenting with decreased dopamine D2 receptor density; and hence to predict L-Dopa effectiveness. Further studies are needed to evaluate the vaue of IBZM tomoscintigraphy in the different Parkinson's like diseases.

Imaging of pulmonary disease in scleroderma with J001X scintigraphy

BACKGROUND

J001X is an acylated poly-galactoside isolated from the membrane of Klebsiella and able to interact with macrophages, mainly in their activated state. The aim of the present study was to determine the ability of 99m-labelled technetium (99mTc)-J001X scintigraphy to image pulmonary disease, defined by high resolution computed tomographic scanning and pulmonary function tests, in patients suffering from scleroderma.

METHODS

Patients were considered to have pulmonary disease when they had at least two positive signs on high resolution computed tomography, or a decrease in lung volume and single breath carbon monoxide transfer, or both, with no disease process other than scleroderma in their medical history. Positive J001X scintigraphic imaging was defined by symmetrical bilateral pulmonary fixation three and five hours after inhalation of 99mTc-J001X. J001X scintigraphic results were compared with disease activity as indicated by bronchoalveolar lavage (BAL) fluid lymphocytosis.

RESULTS

Seventeen patients were studied, in 12 of whom J001X scintigraphy was positive. There was no correlation between BAL lymphocytosis and J001X scintigraphic findings, nor between BAL and pulmonary scleroderma. This was not surprising because of the high specificity of macrophage targeting by J001X.

CONCLUSIONS

Follow up of a larger population over a longer period is needed to establish whether there is a prognostic value for positive J001X scintigraphic findings in scleroderma.

Reliability of low-frequency auditory stimulation studies associated with technetium-99m hexamethylpropylene amine oxime single-photon emission tomography

Development of auditory stimulation tests associated with single-photon emission tomography (SPET) shows evidence of variations in perfusion related to the stimuli. Three brain SPET examinations with technetium-99m hexamethylpropylene amine oxime were performed on eight right-handed adults with normal hearing, the first one without stimulation and the other two associated with a 500-Hz/30-dB stimulation of the right ear. Temporal regions of interest covering auditory areas, as well as parietal ones (internal control), were drawn on three successive coronal slices. A cortico-cerebellar index R was calculated, and the variation in activity was defined for each subject using the ratio R poststimulation--R prestimulation/R prestimulation. A significant increase in the temporal cortex count occurred in all subjects. This increase was bilateral, except for one subject in whom it was not significant on the right side. This result recurred during the second stimulation study. Overall the response of the left temporal cortex was stronger, although the asymmetry was not significant. The asymmetry repeated itself after each stimulation. The perfusion response is globally reliable in our study. We must ascertain how sensitive this test is with regard to deaf adults and adults with normal hearing before extending its use to children.

Perfusion response during electrical stimulation of the auditory nerve in profoundly deaf patients: study with single photon emission computed tomography

Brain activation procedures associated with single photon emission computed tomography (SPECT) recently have been developed in healthy controls and in diseased patients to help in their diagnosis and treatment. We investigated the effects of an electrical stimulation of the auditory nerve on the cerebral distribution of 99mTc-HMPAO in seven profoundly deaf adults. The promontory test was positive (PT+) in six patients and negative (PT-) in one. A count increment of the temporal cortex was observed in all patients, and was higher in all patients with PT+ (right 20%, left 19%) than in the patient with PT- (right 9%, left 3%). These results led us to consider 99mTc-HMPAO brain SPECT imaging as a potential preoperative test for cochlear implant. It might be helpful for the evaluation of cortical perfusion response to an electrical stimulation. Sensitivity tests for the method are requested before this clinical application.

Comparison of two radioiodinated ligands of dopamine D2 receptors in animal models: iodobenzamide and iodoethylspiperone

Several iodinated compounds have been developed for in vivo exploration of dopamine D2 receptors by SPECT. It is of great value to understand if the same information could be obtained with different radioligands. For this purpose, we compared in vivo properties of two iodinated ligands, iodoethylspiperone (IES) and iodobenzamide (IBZM), using different pharmacological and lesioning treatments in rats. Cerebral biodistribution performed by ex vivo autoradiograms and dissection of brain areas showed that IES and IBZM bound specifically to D2 receptors since a pre-injection of haloperidol prevented accumulation of both ligands. In contrast, when haloperidol was injected after IES or IBZM, only IBZM was displaced from its binding sites. This could be explained partly by a process of dopamine-dependent internalization with IES. The response to striatal quinolinic acid infusion for lesioning post-synaptic neurons was very different for IES and IBZM. In this model a decrease in IBZM accumulation occurred, corresponding to the loss of D2 receptors located on post-synaptic neurons. In contrast, a unexpected increase in IES accumulation was observed on the lesioned side. From these results we concluded that IES and IBZM, two iodinated ligands belonging to different pharmacological families, bound specifically to dopamine D2 receptors. However they have different properties in animal models. Therefore, it appears that IBZM is a more suitable ligand than IES to detect modifications of D2 receptors by in vivo exploration.

Postoperative assessment of cerebral blood flow in subarachnoid haemorrhage by means of 99mTc-HMPAO tomography

Regional hypoperfusion is a very frequent complication of subarachnoid haemorrhage (SAH), being related to vasospasm in the majority of cases. Twenty-six patients who were admitted for SAH underwent follow-up with technetium-99m hexamethylpropylene amine oxime single photon emission tomography (SPECT) 3 and 8 days after surgery. Fifteen patients of these had one more examination 15 days after surgery. The degree of hypoperfusion was quantified using an index of asymmetry which allow the comparison of two symmetrical regions of interest (ROIs) on the transaxial slice which presented the greatest perfusion defect. Comparison of CT data, transcranial Doppler data and clinical signs with the perfusion as quantified by 99mTc-HMPAO SPECT indicates that a difference in counts of less than 10% between the two symmetrical ROIs is of no diagnostic value. Follow-up of the brain perfusion clearly shows that the most pronounced hypoperfusion was observed just after surgery, with progressive normalization at 8 and 15 days after surgery. 99mTc-HMPAO SPECT performed 8 days after surgery allows prediction of the clinical outcome. For these reasons, 99mTc-HMPAO SPECT, which is the only method for follow-up of cerebral perfusion in routine clinical practice, should be the first examination to be performed after surgery in patients with SAH.

Scintigraphy with J001 macrophage targeting glycolipopeptide. A new approach for sarcoidosis imaging

Scintigraphy with radiolabeled J001 as a ligand for macrophage targeting is a new approach for sarcoidosis imaging. J001 is a fully characterized acylated peptido-poly (1,3) galactoside isolated from Klebsiella membrane proteoglycans and able to bind electively recruited macrophages. Its physiochemical properties allow rapid absorption by the respiratory tract when this agent, labeled by 99m technetium, is administered as an aerosol. Images are obtained within 3 to 5 h after inhalation. In the present study, we determined the ability of J001 scintigraphy to localize areas of sarcoidosis involvement in 22 patients compared with gallium scanning in ten of them. Nineteen patients underwent bronchoalveolar lavage (BAL) and serum angiotensin-converting enzyme (ACE) assay. J001 scintigraphy was also performed on a control group of six patients with extrathoracic melanoma, in whom J001 scintigraphy was used to evaluate the cutaneous extent of the tumor and the lymph node involvement. In this control group, no fixation appeared in the thoracic area. In the sarcoidosis group, 18 positive results were observed. One stage 0 patient had a mediastinal fixation. Five of the six stage 1 patients had a fixation located in the mediastinum, the lungs, and the wrists. Five of the six stage 2 patients had positive foci located in the mediastinum or the lung areas and in the myocardium in one of them. Six of the nine stage 3 patients had positive J001 scintigraphy occurring in the lungs and/or the mediastinum. One patient had a fixation on the main bronchi. J001 scintigraphy and gallium scanning, performed in ten patients, were positive in seven of them. There were discrepancies between the BAL results and J001 scintigraphy, as well as between the ACE results and J001 scintigraphy. In conclusion, 99mTc-J001 scintigraphy appears to be a sensitive and rapid technique for the imaging of thoracic sarcoidosis at the three stages of the disease.

Synthesis and in vitro binding properties of halogenated analogues of GBR as new dopamine uptake carrier ligands

We present the original synthesis of two halogenated analogues of the diphenyl piperazine GBR, bromo-GBR and iodo-GBR, as new dopamine uptake carrier ligands. The derivatives were purified by HPLC and chemically characterized. Bromo-GBR and iodo-GBR and iodo-GBR are potent inhibitors of [3H]GBR 12935 binding to rat striatal membrane, with Ki values of 116 and 113 nM, respectively. We prepared iodo-GBR labeled with iodide-125 from the brominated derivative and concluded that [123I]iodo-GBR could be a potential tool to explore the in vivo dopamine uptake carrier.

Estrogen receptor imaging with 17 alpha-[123I]iodovinyl-11 beta-methoxyestradiol (MIVE2)--Part II. Preliminary results in patients with breast carcinoma

17 alpha-[123I]Iodovinyl-11 beta-methoxyestradiol was injected into 19 women: group 1 (n = 8), initial evaluation of breast cancer; group 2, (n = 11) postoperative follow-up including 9 patients with bone metastases. The primary tumor (size: 8-10 mm) was visualized by breast tomoscintigraphy in 2/4 patients of group 1 with high estrogen receptor concentration (162-445 fmol/mg) and was not detectable in 4 patients with low estrogen receptor concentration (6-32 fmol/mg). Axillary lymph node metastases were detected in 1 patient of group 1 and in 1 patient of group 2. In 4 patients of group 2 with previous primary tumor containing estrogen receptors, MIVE2 uptake in bone metastases was demonstrated. MIVE2 scintigraphy is an original, specific and non-invasive method for breast cancer estrogen receptor imaging in primary and in metastatic tumors.

Cortical perfusion response to an electrical stimulation of the auditory nerve in profoundly deaf patients: study with technetium-99m hexamethylpropylene amine oxime single photon emission tomography

Brain activation procedures associated with single photon emission tomography (SPET) have recently been developed in healthy controls and diseased patients in order to help in their diagnosis and treatment. We investigated the effects of a promontory test (PT) on the cerebral distribution of technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) in 7 profoundly deaf patients, 6 PT+ and one PT-. The count variation in the temporal lobe was calculated on 6 coronal slices using the ratio (Rstimulation-Rdeprivation)/Rdeprivation where R = counts in the temporal lobe/whole-brain count. A count increase in the temporal lobe was observed in all patients and was higher in all patients with PT+ than in the patient with PT-. The problems of head positioning and resolution of the system were taken into account, and we considered that the maximal count increment was related to the auditory cortex response to the stimulus. Further clinical investigations with high-resolution systems have to be performed in order to validate this presurgery test in cochlear implant assessment.

Estrogen receptor imaging with 17 alpha-[123I]iodovinyl-11 beta-methoxyestradiol (MIVE2)--Part I. Radiotracer preparation and characterization

It is important to know the estrogen receptor rate in breast carcinoma management. Thus, an in vivo and atraumatic method would be very useful. Different ligands have been proposed for this. We present here the specific synthesis of 20E- and 20Z-17 alpha-iodovinyl-11 beta-methoxyestradiols and their biological characterization as estrogen receptor ligands. The two isomers were analysed by current chemical methods (NMR) and purified by HPLC. We carried out an in vivo study with 21-day-old Swiss mice to compare properties of the two ligands. The 20E-MIVE2 showed the best affinity for estrogen receptors, the uterus-to-blood ratio was 15-fold higher for the trans derivative. We enhanced the in vivo and in vitro properties of the 20E-MIVE2: the affinity constant was determined by Scatchard analysis, Kd = 16 x 10(-10) M, and biodistributions were performed with unlabelled estradiol pre-injection. We concluded that 20E-MIVE2 can be used for a feasibility study in patients with breast carcinoma.

Increment of brain temporal perfusion during auditory stimulation. Preliminary study with technetium-99m HMPAO SPET

A study on the dynamic exploration of the auditory pathway is presented, in which technetium-99m hexamethylpropylene amine oxime single-photon emission computed tomography (SPET) was used in volunteers with normal hearing. Changes in 99mTc-HMPAO distribution were calculated using a region of interest/whole-brain count ratio. The results showed a temporal perfusion increment of 17% (right) and 19% (left) during tonal supraliminar stimulation, which was significantly different from the control ROI. Sensitivity tests for the method were requested before any clinical application.

[131I]metaiodobenzylguanidine treatment of a malignant paraganglioma

The bone metastases of a malignant, non-secreting paraganglioma were treated with [131I]metaiodobenzylguanidine (131I-MIBG) over a 10-year period. Initial treatment (131I-MIBG: 9.6 GBq) resulted in a decrease in the number of bone metastases from 16 to 2. At three years, a relapse with primary tumor regrowth and liver metastasis was again treated with 131I-MIBG (22.2 GBq). A decrease in the number of bone metastases and MIBG uptake was again observed.

Diagnosis of medullary carcinoma of the thyroid (MCT) by calcitonin assay using monoclonal antibodies: criteria for the pentagastrin stimulation test in hereditary MCT

A new calcitonin (CT) immunoradiometric assay, using anti-11-7 and anti-24-32 CT fragment monoclonal antibodies was evaluated and compared to classical RIA. The sensitivity was 2.5 ng/L, the normal basal level (n = 83) was lower than 10 ng/L, the response to pentagastrin stimulation in control subjects was absent in nine and between 10-30 ng/L in nine others. (mean, 15.4). In patients with renal failure the basal level was increased between 10-52 ng/L. In patients with medullary thyroid carcinoma (MTC; n = 28), the basal level was between 189-28,900 ng/L. A pentagastrin test was performed as screening for familial MTC in eight patients with confirmed MTC at subsequent surgery; the calcitonin peak was equal or greater than 38 ng/L. Large differences exist between CT levels measured by RIA and immunoradiometric assay. The latter method provides a greater sensitivity to pentagastrin test and allows a better identification of microcarcinoma in hereditary cases of MTC.

The potential usefulness of condensed image processing of sequential lymphoscintigrams in patients with lymphedema

Condensed image processing (CIP), a computerized technique of scintiscans that generates a vertical distribution of activity as a function of time in a single image, was applied to isotopic lymphoscintigrams of four patients with leg lymphedema. By "condensing" information gained from multiple images into a single image, CIP better evaluates ascending progression of radiolabeled colloid in peripheral lymph and better localizes stagnant areas. In "high lymph flow failure," CIP also depicts radioactive "bursts" suggestive of increased lymphatic truncal contractility. This data processing method improves interpretation of dynamic scintiscan recordings and seems ideally suited for evaluation of peripheral lymph kinetics.

Iodobenzamide for in vivo exploration of central dopamine receptors: evaluation in animal models of supersensitivity

Iodobenzamide is a promising agent to investigate D2 receptors by SPECT in living human brain. In this work, we have evaluated this radiolabeled compound in two animal models of D2 receptors supersensitivity. In the first model, rats were treated chronically with haloperidol during three weeks (S.C. injection of 0.5 mg/kg/day). One week after the last day of treatment, they were I.V. injected with 125I-IBZM. In vivo specific binding study showed a 45 percent increase of 125I-IBZM fixation in the striatum of treated rats. In a second step of experiments, animals were unilaterally lesioned by a stereotaxic injection of 6-OHDA in the substantia nigra, 23 days before receiving 125I-IBZM. Autoradiographic analysis of coronal brain sections showed a 38 percent enhancement of 125I-IBZM in vivo binding in the striatum on the lesioned side as compared to the contralateral intact side; this increase occurred in striatal lateral area. These data demonstrate that 125I-IBZM is convenient to detect alterations of dopamine D2 receptors in vivo in the rat. Thus IBZM labelled with 123I can be a very useful imaging agent for the exploration of D2 receptors in pathological situations.

Iodoethylspiperone, a new potential agent for exploration of central dopamine D2 receptors: synthesis and preliminary in vivo study

We synthesized a new spiperone derivative: iodoethylspiperone (IES) to perform dopamine D2 receptor exploration by SPECT. IES was prepared from a precursor: tosylethylspiperone, and characterized by i.r. and 1H-NMR analyses. [125I]IES was obtained with 80% yield. In vivo biodistribution in rats showed a high and specific uptake in the striatum. The uptake ratio between the striatum and the cerebellum reached a maximum value 4 h after injection (10.05 +/- 2.81). IES labeled with 123I should be a promising new agent to investigate D2 receptors in the living human brain.

[125I]MIBG uptake and release in different regions of the rat brain

Radioiodinated m-iodobenzylguanidine [( 125I]MIBG) and tritiated norepinephrine [( 3H]NE]) uptake and release were compared, in different regions of the brain of the rat. The classification of the regions according to uptake was the same for both tracers:striatum greater than hypothalamus greater than hippocampus greater than cortex greater than brainstem. Tetrabenazine (TBZ), a granular monoamine uptake inhibitor reduced the uptake in the different regions. The inhibition rate was higher for [3H]NE uptake than for [125I]MIBG. The spontaneous release was the same for [125I]MIBG and [3H]NE and was the lowest in the striatum. The K+ stimulated release of [3H]NE was more complete than the release of [125I]MIBG and was the most important in the striatum. From these results, it is inferred that MIBG enters the brain tissue via NE uptake mechanisms. It appears that MIBG is stored in the chromaffin granules, as NE, but also in the cytoplasm. A modified molecule derived from MIBG which would cross the blood-brain barrier, would then appear as a potential scintigraphic marker of monoamine uptake, storage and release.

Factorial analysis in radionuclide lymphography: assessment of the effects of sequential pneumatic compression

The effects of intermittent pneumatic compression (IPC) in 12 patients with lower or upper limb lymphedema were studied using a computer-based technique (factorial analysis) of dynamic lymphoscintigraphy. After subcutaneous injection of radiocolloid into the first interdigital web space of the arm or leg, scintigraphic recordings consisted of 40 consecutive one-minute frames of both lower extremities or an edematous upper extremity. Pneumatic compression by Euroduc (6 patients) or by Lymphapress (6 patients) was applied during the final 20 minutes of the recording. A three factors factorial analysis (FA) was performed successively for each extremity. FA allowed "uncontaminated" curves to be displayed distinct from neighboring structures and corresponded to dynamic tracer activity in the interstitium, at the injection site, and within lymphatic vessels. Based on the results of lymphatic vascular factorial analysis, a beneficial effect of IPC was detected in 18 of 22 limbs examined. FA processing suggested that IPC facilitated radiocolloid transport in the proximal portion of the limb and also propelled tracer from the injection site toward the lymphatics. The effect of IPC was evident as soon as external compression therapy began and was similar with either mechanical unit. Residual tracer activity in peripheral lymphatics 20 minutes after application of IPC was higher in the edematous as compared with the normal limbs. FA processing is a new and potentially valuable method to evaluate the effects of external pneumatic compression in the management of peripheral lymphedema.

Linkage analysis of hereditary thyroid carcinoma with and without pheochromocytoma

The use of polymorphic DNA segments as markers for the gene for the multiple endocrine neoplasia (MEN) syndrome, type 2a, allows the identification of family members at high risk for developing medullary carcinoma of the thyroid and other tumors, especially pheochromocytoma. Several families have also been identified in which medullary thyroid carcinoma is inherited, but pheochromocytoma is not seen. We have analysed 18 families, 9 with MEN 2A and 9 with medullary carcinoma of the thyroid without pheochromocytoma, with probes specific for the pericentromeric region of chromosome 10 and conclude that the mutations for the two presentations are closely situated. Genetic heterogeneity of the susceptibility locus was not seen among this sample of 18 families. The genetic mutation for medullary carcinoma was in disequilibrium with the marker alleles of the two closely linked probes, IRBPH4 and MCK2. These data suggest that different mutant alleles of the same gene or closely linked mutations account for the variation in penetrance of pheochromocytoma in families with hereditary medullary thyroid carcinoma.

Factorial analysis of dynamic lymphoscintigraphy in lower limb lymphoedema

The purpose of this work is to assess the contribution of factor analysis to the interpretation of dynamic lymphoscintigraphy. Twenty six adult patients with a lower limb lymphoedema and five control patients were studied. The technique involved a 3 mCi lymphovectoscint* 99Tcm-labelled ammonium sulphur colloid, bilateral pedal subcutaneous injection. Recording consisted of 40 consecutive 1-min frames of both legs followed by static pictures of each leg and pelvis at 40 min and 4 h after injection. The analysis of static pictures allowed a classification of patients into three groups: enhanced pattern, hypoplasia and dermic reflux. To evaluate better the different kinetic components of the sequential pictures, a factorial analysis (FA) software package was used. FA processing enabled the extraction from the dynamic series of different dynamic components, factorial curves and their associated factorial images which represent the anatomic structures with the same temporal behaviour. In each pattern the results of dynamic recording and of three FA factors were compared. FA provides an analytical temporal and spatial description of the dynamic sequence by extracting the different kinetic components; it yields a better differentiation of vessel and interstitium activity. It also provides some clues towards the understanding of oedema physiopathology and is of potential interest for the management of lymphoedema.

Therapeutic effectiveness of iodine-131 MIBG metastases of a nonsecreting paraganglioma

This case report describes the treatment of the bone metastases of a nonfunctioning sympathetic paraganglioma, with [131I]MIBG. After primary tumor excision and unsuccessful external radiotherapy, the patient received three therapeutic doses of [131I]MIBG, resulting in a reduction of the number and volume of metastases, and an improvement of the general condition. At 3 yr following [131I]MIBG therapy, the patient remained in remission. [131I]MIBG appears to be an efficient and safe agent for treating malignant sympathetic paraganglioma.

Comparison of MIBG and monoamines uptake mechanisms: pharmacological animal and blood platelets studies

The uptake of MIBG, a scintigraphic agent widely used in the detection of APUD tumours, was studied with a pharmacological approach on an in vitro and an in vivo models. MIBG as well as norepinephrine (NE) was taken up by human blood platelets, a model for presynaptic nerve endings amine uptake, with a thermodependant mechanism. MIBG and NE uptake was inhibited by desimipramine and reserpine. However, MIBG but not NE uptake was inhibited by fluvoxamine, a serotonin (5HT) uptake inhibitor. This suggests that MIBG is a NE and also a 5HT uptake tracer which involves uptake one and vesicular storage mechanisms. In rats treated with 6-hydroxydopamine to induce a chemical sympathectomy, we observed an inhibition of uptake similar for MIBG and NE in the heart, the salivary glands and the spleen, but no effect was observed in the liver. Some clinical inferences to best investigate specific monoamine uptake are drawn from these results.

[Thyroid ectopia and Basedow's disease]

Graves' disease was diagnosed in a 35-year old woman with a history of myxoedema in childhood. Clinical data, ultrasonography and radioisotope scanning showed that the disease had developed in an ectopic subhyoid thyroid gland. Although numerous thyroid diseases associated with an ectopic thyroid have been described, Graves' disease does not seem to be frequent since only one case has been published so far.

[Limitations of scintigraphy using metaiodobenzylguanidine for locating pheochromocytomas. Apropos of 2 cases]

Two cases of MIBG (metaiodobenzylguanidine) scintigraphy are reported: the first case concerns a female patient hospitalized for high blood pressure (HBP) with symptoms evocative of pheochromocytoma. Urinary titration of catecholamines metabolites, which are usually abnormally high, and tomodensitometry permit the visualization of a left adrenal tumor. On the contrary, the MIBG scintigraphy does not show any abnormal fixation. After resection, the pathological examination confirms the diagnosis of pheochromocytoma. The second case concerns a female patient hospitalized for HBP with, on the chest X-Ray, a left postero-inferior density. Serum and urinary catecholamine levels are normal. Tomodensitometry confirms the tumor of the posterior mediastinum and the MIBG scintigraphy demonstrates a focus of thoracic opposite the tumor. After resection, the pathological examination shows an ectopic supernumerary bronchial bud. These two cases illustrate the limitations of MIBG scintigraphy to locate pheochromocytomas. There are false negative (10%) which may be explained by an insufficient uptake of the tracer by the tumor, by an insufficient image formation or by medication interferences. On the contrary, there may be false positives because of histochemical similarities between the chromaffin tissues and certain glandular or neural tumors. Nevertheless, in spite of serious limitations, which we must be aware of, MIBG scintigraphy remains the best primary examination for the location of pheochromocytomas.

MIBG and catecholamine storage in the brain: an in-vitro study

The uptake and release of mIBG, a tracer of the monoamine uptake and storage function, were studied on superfused rat cerebral cortex sections. mIBG was taken up and released by a mechanism comparable to that of norepinephrine (NE), but this storage appeared to be less specific for mIBG than for NE. This implies that when mIBG is used as a scintigraphic tracer of monoaminergic synaptic vesicles, imaging should be delayed long enough to ensure release of the molecule from its nonspecific binding sites.

Radioiodinated meta-iodobenzylguanidine uptake in medullary thyroid cancer. A French cooperative study

Fifty meta-iodobenzylguanidine (MIBG) scintiscans were performed in three groups of medullary thyroid cancer (MTC) patients. Group 1 (n = 11) included treated patients with normal calcitonin levels; Group 2 (n = 24) included patients with elevated calcitonin levels due to sporadic and isolated MTC; Group 3 (n = 15) included patients with elevated calcitonin levels due to familial MTC or multiple endocrine neoplasia Type IIA syndrome (MEN). In Group 1 three pheochromocytoma were depicted by MIBG scintiscan. In Group 2 MTC was seen in a small number of patients (3 of 24). In Group 3, besides adrenal hyperplasia and pheochromocytoma four patients, MIBG scintigraphy showed where MTC had localized and spread in almost half of patients (7 of 15). MIBG uptake occurred in patients with relatively high calcitonin level (greater than 0.6 nmol/l). These data indicate that in patients with familial MTC or MEN syndrome, MIBG scintiscan can be useful not only in detecting associated pheochromocytoma, but also in showing MTC.

Visualization of the thoracic duct by lymphoscintigraphy

Imaging of the thoracic duct is usually performed by radiological lymphography. However, this procedure, which uses an oil based dye injected directly into the lymph channels, has some adverse effects. In this paper we note that lymphoscintigraphy, a physiological and non invasive method, may visualize thoracic duct abnormalities, and might be particularly useful when radiological lymphography is contraindicated.

Use of lymphscintigraphy in traumatic chylous ascites

This report describes the use of lymphscintigraphy in a patient with traumatic chylous ascites. Radioactivity "leakage" near the origin of the thoracic duct and accumulation into the peritoneal cavity were delineated.

Scintigraphy in duodeno-gastric reflux: a new method of quantification

A prospective study is undertaken in order to demonstrate the ability of scintigraphy with a non compartmental analysis to quantitate the duodeno-gastric reflux. 24 patients have been examined, sitting in front of a gamma camera: 12 with an endoscopically proved reflux and 12 normal subjects or volunteers. About 15 min after an injection of 148 to 222 MBq 99Tcm-IDA they were given a meal labelled with 37 MBq 113Inm-DTPA. Images were recorded for 2 h. Equal size gastric and duodenal ROIs were selected over the duodenum and stomach, avoiding overlap with neighbouring organs. The reflux index based upon the occupancy principle is calculated from the gastric and duodenal curves. It is the ratio between the gastric and duodenal ROI IDA fluxes. The value of the reflux index is 3 +/- 1.8% in normal subjects and 45 +/- 33% in pathological cases. Our method, which does not require intubation, quantitatively evaluates biliary reflux independently of injected dose and hepatic or gallbladder function.