Unexpected detection of an astrocytoma by poorly labeled Tc-99m HMPAO.
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Aged↗
Biomedical subjects
M L Calcagni
Publications and source records attributed to M L Calcagni.
SPET monitoring of perfusion changes in auditory cortex following mono- and multi-frequency stimuli.
AIM: In order to assess the relationship between auditory cortex perfusion and the frequency of acoustic stimuli, twenty normally-hearing subjects underwent cerebral SPET. METHODS: In 10 patients a multi-frequency stimulus (250-4000 Hz at 40 dB SL) was delivered, while 10 subjects were stimulated with a 500 Hz pure tone at 40 dB SL. The prestimulation SPET was subtracted from poststimulation study and auditory cortex activation was expressed as percent increments. RESULTS: Contralateral cortex was the most active area with multi-frequency and monofrequency stimuli as well. A clear demonstration of a tonotopic distribution of acoustic stimuli in the auditory cortex was achieved. In addition, the accessory role played by homolateral acoustic areas was confirmed. CONCLUSION: The results of the present research support the hypothesis that brain SPET may be useful to obtain semi-quantitative reliable information on low frequency auditory level in profoundly deaf patients. This may be achieved comparing the extension of the cortical areas activated by high-intensity multifrequency stimuli.
Acoustic Stimulation↗
Neuropsychological tests and [99mTc]-HM PAO SPECT in the diagnosis of Alzheimer's dementia.
Twenty-three patients with Alzheimer's dementia (AD) in relatively early stages and 40 patients with other cognitive disorders of vascular or degenerative aetiology underwent neuropsychological examination and [99mTc]-HM PAO single photon emission computed tomography (SPECT). In contrast to the commonly accepted notion of a posterior temporoparietal reduction of tracer uptake as the typical SPECT pattern of AD, the most consistent feature found in the SPECT images of our AD patients was a hippocampal uptake deficit, associated with a variable degree of temporal, parietal and frontal deficit (extending from the posterior to the anterior regions), according to the severity of the disease. These results support the theory of AD as a "hippocampal dementia", at least in the early stages. Neuropsychological tests were found to be somewhat more specific and more accurate than SPECT in distinguishing AD from non-AD cases.
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[The scintigraphic prediction of residual lung function after lobectomy in patients with bronchial carcinoma].
The scintigraphic prediction of residual pulmonary function after pneumonectomy has been validated in a number of studies while scintigraphy is not standardized in case of lobectomy. This study was aimed at investigating the accuracy of the scintigraphic prediction of post-lobectomy lung function using Wernly method. We examined 43 patients with bronchial carcinoma: 20 of them underwent pneumonectomy and 23 underwent lobectomy. The pulmonary function data (vital capacity, CV, and forced expiratory volume in one second, VEMS) predicted by quantitative lung scan were compared with those observed in the postoperative follow-up. A good correlation between predicted and observed data was obtained in both the pneumonectomized group (r = 0.77 and 0.78 for CV and VEMS, respectively; p < 0.005) and the lobectomized group (r = 0.74 and 0.79 for CV and VEMS, respectively: p < 0.005). It can be concluded that the method used for the scintigraphy prediction of post-lobectomy pulmonary function is as accurate as the post-pneumonectomy method and can be used reliably in the clinical practice.
Aged↗
Use of [123I]MIBG to assess cardiac adrenergic innervation: experience in hypertensive cardiopathy and left ventricular aneurysms.
[123I]MIBG has been proposed as a suitable tracer of the adrenergic system of the heart. The aims of this study was to investigate the adrenergic functional status of the heart in hypertensive patients with left ventricular hypertrophy (LVH), and to evaluate the distribution of neuroadrenergic terminals in patients with left ventricular aneurysms (LVA) presenting complex arrhythmias. We studied 21 patients (4 normals, 11 with LVH and hypertension, and 6 with previous myocardial infarction, LVA and complex arrhythmias) who underwent series of [123I]MIBG planar scans (from 0.5 to 24 hours p.i.) and SPECT scans using both [123I]MIBG and 201Tl. Data quantification was performed by calculating the heart/mediastinum ratio (planar scan) and the percent uptake in 5 myocardial regions (SPECT scan). No significant differences between normals and hypertensive patients were found either in the heart/mediastinum ratio or in the regional distribution of [123I]MIBG and 201Tl. In hypertensive patients the uptake of [123I]MIBG was significantly higher than that of 201Tl in the septal wall while in the lateral and inferior walls it was significantly lower. In patients with anteroapical myocardial infarction (MI), the size of the [123I]MIBG defect was slightly smaller than the 201Tl defect; moreover a constant, severe [123I]MIBG defect was observed in the inferior walls whereas 201Tl uptake was normal. We conclude that while in hypertensive patients adrenergic innervation seems to be slightly impaired as compared to myocardial perfusion, in patients with MI a large area of functional or anatomical denervation may be detected despite the preserved perfusion and viability; this mismatch may be the trigger of complex arrhythmias.
3-Iodobenzylguanidine↗
Use of metaiodobenzylguanidine (MIBG) in pneumology.
Norepinephrine (NE) is one of the many biologically active substances that are metabolized by the lung. The norepinephrine uptake in the lung has been widely investigated in animal studies in order to detect abnormalities of the endothelial cells. 131I- or 123I-labelled metaiodobenzylguanidine (MIBG) is a radioactive tracer that shares several metabolic pathways with NE; it has been used instead NE or both in animal and in human studies for the same purposes. It has been definitely demonstrated that MIBG lung uptake following intravenous administration is a reliable marker of minimal endothelial cell lesions and it allows one to investigate several conditions involving damage to the lung vasculature such as adult respiratory distress syndrome, post-actinic lung fibrosis or chemotherapic lung toxicity. MIBG could also potentially be used as a tracer of the neuroadrenergic system of the airways, once it has been deposited in the whole branches of the bronchial tree. With this in mind we evaluated the feasibility of the administration of MIBG in radioaerosol form. We first performed a chromatographic study on [123I]MIBG aliquots aerosolized for variable lengths of time (2-30 minutes). Radiochemical purity was always over 96%, thus demonstrating that aerosolization does not significantly modify the stability of the tracer. We then compared both the lung clearance curves and the scintigraphic images in two groups of normal subjects who respectively underwent [123I]MIBG and 99mTc-DTPA radioaerosol dynamic scintigraphy. We found that MIBG clearance to be significantly lower than that of DTPA (135 +/- 32 minutes versus 69 +/- 27 minutes, p < 0.01), probably due to its being trapped in the adrenergic nerve endings of the airways. The pulmonary distribution of both tracers was homogeneous, as demonstrated by the correspondence of the values for the aerosol penetration index in both groups of subjects. Such results warrant further research and pharmacologic tests.
3-Iodobenzylguanidine↗
In vitro and in vivo studies with no-carrier added radioiodinated MIBG.
An important drawback of radioiodinated MIBG prepared by isotopic exchange (maximum specific activity: 100 Ci/mmol) is that a considerable amount of carrier is present in the "ready to use" radiopharmaceutical, thus affecting MIBG uptake in the target cells. To improve the therapeutic utility of MIBG an interesting method was developed for the no-carrier-added (n.c.a.) radioiodination of MIBG via a halodesilylation reaction using 3-trimethylsilybenzylguanidine (TMSBG) as precursor. In order to investigate its possible clinical usefulness, n.c.a. [125I]- and [131I]MIBG was prepared according this procedure. HPLC analysis of the labeling mixture showed that the labeling yield reached values greater than 98% within 20 minutes at 70 degrees C. HPLC fraction containing [131I]MIBG was then recovered and tetrahydrofurane was removed under nitrogen stream. Biodistribution studies were performed in BALB/c normal mice and compared with those obtained using [131I]MIBG prepared by isotopic exchange. Preliminary results showed that at 4 hours myocardial uptake was significantly higher than that of c.a. MIBG (20.3 +/- 0.4 %ID/g). Adrenal uptake gradually increased over time; at 24 hours adrenal uptake was almost twofold that a 1 hour. MIBG uptake was also studied in the human neuroblastoma cell line SH-SY5Y which has a specific uptake system for MIBG. The kinetic parameters for MIBG in this line are: km = 0.27 +/- 0.03 microM, Vmax = 39.5 + 1.8 pmol/10(6) cell/10 min. Preliminary data from in vitro binding studies showed that significantly higher levels of specifically incorporated radioactivity can be achieved using n.c.a. [125I]MIBG instead of c.a. [125I]MIBG.
3-Iodobenzylguanidine↗
Brain SPET and auditory cortex perfusion. Technical notes and preliminary results.
Auditory cortex stimulation was studied by 99Tcm-hexamethylpropyleneamine oxime (HMPAO) single photon emission tomography (SPET) in 11 patients with normal vestibular and auditory tests, as well as computed tomography. Markedly increased temporal and parietal blood flows were found in left brain cortex, contralateral to the stimulus. The right auditory areas showed moderate hyperactivity. The method might be useful for tonotopic mapping of auditory cortex, using various pure tonal stimuli.
Acoustic Stimulation↗
Correlation of Tc-99m-red blood cell phleboscintigraphy with clinical severity of chronic venous disease.
Equilibrium red blood cell phleboscintigraphy of the lower limbs for the diagnostic management of chronic venous disease has been proposed. The aim of this study was to verify the correlation of the phleboscintigraphic assessment of chronic venous disease with the clinical grading of the severity of the disease, since other diagnostic modalities have been recently demonstrated a poor and only partial correlation. Equilibrium Tc-99m-red blood cell phleboscintigraphy was performed in 27 patients with chronic venous disease. Scintigraphic images of 52 limbs were classified according to a four-class qualitative grading of the severity of the venous disease, and a quantitative scintigraphic index (saphena /femoral ratio) was assigned to each limb. The scintigraphic qualitative grading showed a highly significant correlation with the clinical grading (Rs=0.82, p<0.01), a good interobserver and intraobserver agreement (86.5% and 92.3%, respectively) and more than 90% sensitivity and specificity to identify the categories "minimal or no chronic venous disease" or "more significant disease" (assessed according to the Bayes theorem). Sensitivity and specificity results for the quantitative assessment were not as good. Phleboscintigraphy correlates well with the clinical grading of the severity of chronic venous disease of the lower limbs and may have potential as a valuable diagnostic tool for the noninvasive assessment of chronic venous disease.
Chronic Disease↗
Myocardial SPECT in the study of ischemic heart disease detection of hibernating myocardium and evaluation of cost/benefit ratio.
From over ten years, the assessment of myocardial viability in akinetic zones (stunned or hibernating myocardium) is considered fundamental to the correct management of postinfarction patients. The assessment can be performed with myocardial scintigraphy (201Thallium rest-redistribution, dobutamine stress echocardiography, MRI, 18F-fluorodeoxyglucose PET). A number of experiences have shown that scintigraphy is very sensitive but poorly specific in the assessment of myocardial akinetic zones with contractile functional recovery after revascularization. However, most recent reports have highlighted that the recovery of contractile function is not the single purpose of myocardial revascularization; in fact, it is able to prevent or attenuate remodeling, the contractile reserve is maintained or enhanced, the diastolic function is improved, arrhythmias are prevented, symptoms and functional capacity are improved. Therefore, the role of very sensitive procedures as myocardial scintigraphy or MRI of the heart is still of major diagnostic and prognostic significance. The present socioeconomic situation and the most recent advances in cardiology tend to shift the clinician's interest from the diagnosis to the prognosis of patients with ischemic heart disease and consequently, from maximum diagnostic accuracy to the highest prognostic value and maximum cost/effective benefit. Therefore, the nuclear cardiologist must become familiar with this novel terminology and new diagnostic and prognostic end-points.
Adrenergic beta-Agonists↗