Biomedical subjects

M Salvatore

Publications and source records attributed to M Salvatore.

At least 163 records · Page 9Linked to original sources

PubMed1995

Effect of adenosine on cerebral blood flow as evaluated by single-photon emission computed tomography in normal subjects and in patients with occlusive carotid disease. A comparison with acetazolamide.

BACKGROUND AND PURPOSE: Acetazolamide is commonly used with single-photon CT to assess the cerebrovascular reserve in patients with internal carotid artery stenosis or occlusion. In this study we wanted to evaluate the effects of adenosine, a well-known vasodilatatory compound with a short biological half-life, on brain circulation in humans and compare the results with those of acetazolamide. METHODS: Acetazolamide (1 g) and adenosine (140 micrograms/kg per minute) were injected intravenously on different days in 6 normal subjects and 6 patients: 4 with unilateral stenosis, 1 with bilateral stenosis, and 1 with complete occlusion of the internal carotid artery. Changes in regional cerebral blood flow relative to that of the cerebellum (cortico/cerebellar ratios) from resting conditions were evaluated by 99mTc-hexamethylpropyleneamine oxime and single-photon emission CT. RESULTS: The measured blood flow ratios increased significantly in the normal group 20 minutes after acetazolamide injection in several cortical and subcortical regions, as well as at the 4th minute of a 6-minute adenosine infusion. Regional cerebral blood flow ratio values were higher after adenosine than after acetazolamide in both cortical (frontal and parietal) and subcortical (thalamus and basal ganglia) regions. In 4 of the 6 patients the side-to-side asymmetry increased from the basal resting condition after the injection of acetazolamide and even more so after the injection of adenosine. CONCLUSIONS: Adenosine infusion causes vasodilation of cerebral arteries and can be used for the investigation of cerebrovascular perfusion capacity in patients with carotid occlusive disease. One advantage in the use of adenosine over acetazolamide is the possibility of interrupting the test with reversal of clinical symptoms or patient discomfort within a few minutes.

Acetazolamide↗

PubMed1995

Technetium-99m pentavalent dimercaptosuccinic acid imaging in patients with pituitary adenomas.

We studied the tumor-seeking agent technetium-99m-labeled pentavalent dimercaptosuccinic acid ([99mTc](V)DMSA) to visualize 21 growth hormone (GH)-, nine prolactin (PRL)-, two mixed GH/PRL-, six adrenocorticotrophin (ACTH)-secreting and 15 clinically non-functioning pituitary adenomas, three craniopharyngiomas and one dysgerminoma of the sella. All non-adenomas and 31 out of 53 adenomas were studied before treatment: 22 after surgery and/or radiotherapy. Eight cases of acromegaly were studied before and after chronic treatment with octreotide, whereas three cases of acromegaly, one of prolactinoma and two of non-functioning adenoma were imaged before and after adenomectomy. As a control group, 27 patients without any clinical evidence of pituitary adenoma were studied: 10 of them were operated on previously and treated with iodine-131 for metastatic thyroid carcinoma, 10 had brain tumors and the remaining seven patients had functional pituitary hypersecretion (four Klinefelter's syndrome, two primary hypothyroidism and one Addison's disease). The scintigraphy was repeated after testosterone in Klinefelter's syndrome, L-thyroxine in primary hypothyroidism and cortisone administration in Addison's disease. Seventeen GH-secreting (81%), seven PRL-secreting (78%), three ACTH-secreting (50%), 15 non-functioning (100%) and one (50%) mixed adenoma significantly concentrated [99mTc](V)DMSA, showing elevated tumor-to-background (T/B) ratios. The T/B ratios were similar in untreated and surgically treated adenomas (11.2 +/- 5.6 vs 11.8 +/- 6.2). Radiotherapy significantly lowered the [99mTc](V)DMSA uptake to 5.1 +/- 2.8 (p < 0.1 vs untreated patients). Non-adenomatous lesions of the sella turcica did not concentrate [99mTc](V)DMSA in the pituitary as well as brain tumors and 8 out of 10 metastatic thyroid cancers. The treatment with octreotide normalized GH and insulin-like growth factor I levels and reduced [99mTc](V)DMSA from 15.7 +/- 4.8 to 13.5 +/- 3.9 (p < 0.05). Conversely, adequate substitutive therapy completely inhibited the uptake of the radiotracer in Klinefelter's syndrome, in primary hypothyroidism and in Addison's disease. The [99mTc](V)DMSA scintigraphy showed an overall sensitivity of 81% (43/53) in detecting pituitary adenomas, which was increased to 95% for lesions greater than 10 mm in size. High-quality images with minimal total body radiation were obtained, enabling a good in vivo characterization of viable adenomatous tissue as well as an accurate monitoring of the effects of different therapeutic regimens.

Addison Disease↗

PubMed1995

Enhanced detection of viable myocardium by technetium-99m-MIBI imaging after nitrate administration in chronic coronary artery disease.

UNLABELLED: The aim of this study was to assess whether nitrate administration improves the imaging capabilities of 99mTc-MIBI tomography in detecting viable myocardium in coronary artery disease (CAD). METHODS: Thirty-one patients with angiographically proven CAD and chronic LV dysfunction (ejection fraction 39% +/- 9%) underwent two 99mTc-MIBI studies on separate days: one under rest conditions and the other after nitroglycerine (0.005 mg/kg per os) administration. Within 1 wk, all patients also underwent rest-redistribution 201Tl imaging. Eight patients were also studied by echocardiography before and 5 +/- 3 mo after coronary revascularization. RESULTS: On resting 99mTc-MIBI images, 302 segments had normal uptake, 183 segments had moderately reduced uptake and 197 had severely reduced uptake. Of the segments with severely reduced uptake, 54 (27%) had increased uptake after nitroglycerine and were viable on 201Tl images. Of the 143 (73%) segments with severely reduced 99mTc-MIBI uptake and no change after nitroglycerine, 81% were nonviable on 201Tl images. In the eight patients studied before and after revascularization, 87% of segments with reversible 99mTc-MIBI defects and abnormal LV function demonstrated functional recovery after revascularization, whereas 89% of segments with irreversible 99mTc-MIBI defects did not. CONCLUSION: In patients with chronic ischemic LV dysfunction, nitrate administration improved the detection of severely hypoperfused but still viable myocardium on 99mTc-MIBI images.

Coronary Circulation↗

PubMed1995

Myocardial viability index in chronic coronary artery disease: technetium-99m-methoxy isobutyl isonitrile redistribution.

UNLABELLED: The purpose of this study was to evaluate whether an additional redistribution image after a rest 99mTc-MIBI injection enhances detection of viable myocardium and predicts functional recovery after coronary revascularization in patients with chronic coronary artery disease (CAD). METHODS: Thirty-one patients (29 men, mean age 55 +/- 10 yr) with proven CAD and left ventricular (LV) dysfunction (ejection fraction 39% +/- 9%) underwent resting 99mTc-MIBI tomography with initial (1 hr) and delayed (5 hr) images. Within 1 wk of MIBI imaging, all patients underwent rest-distribution 201Tl imaging. Eight patients also underwent two-dimensional echocardiography before and 5 +/- 3 mo after coronary revascularization. RESULTS: On the initial 99mTc-MIBI images, 302 myocardial segments were normal, 183 showed moderate and 197 severe reduction of tracer uptake. Of these 197 segments, 47 (24%) demonstrated increased tracer uptake (> or = 10% versus initial) on delayed images (from 43% +/- 8% to 60% +/- 8%, p < 0.001) and were considered as showing 99mTc-MIBI redistribution. These 47 segments were observed in 20 (65%) patients in whom 201Tl images detected viable myocardium in the same segments. In the eight patients studied before and after revascularization, 83% of segments with 99mTc-MIBI redistribution and abnormal LV function showed functional recovery after revascularization, while 96% of segments without 99mTc-MIBI redistribution did not show functional recovery. CONCLUSION: Resting 99mTc-MIBI redistribution frequently occurs in patients with chronic CAD. Acquisition of 99mTc-MIBI redistribution images enhances detection of viable myocardium and predicts functional recovery after revascularization.

Coronary Disease↗

PubMed1995

Reverse redistribution in resting thallium-201 myocardial scintigraphy in chronic coronary artery disease: an index of myocardial viability.

UNLABELLED: The aim of this study was to evaluate whether segments with reverse redistribution on rest-redistribution 201Tl scintigraphy represent viable tissue or scar. METHODS: Nineteen patients (17 men, 2 women; mean age 53 +/- 8 yr) with coronary artery disease underwent rest-redistribution 201Tl study before coronary revascularization. Regional 201Tl uptake was analyzed quantitatively. Regional left ventricular wall motion was assessed before and after coronary revascularization using two-dimensional echocardiography and a three-point scale (1 = normal, 2 = hypokinetic, 3 = akinetic/dyskinetic). Two patterns of reverse redistribution were identified: pattern with normal 201Tl uptake in rest and abnormal in redistribution images and pattern with abnormal 201Tl uptake in rest and a significant decrease in redistribution images. RESULTS: Of the 247 segments analyzed, 85 were classified as normal, 37 as reversible defects, 83 as fixed defects and 42 as reverse redistribution (19 RR-A, 23 RR-B). Segments with RR-A differed from those with RR-B in wall motion score (1.4 +/- 0.7 versus 2.0 +/- 1.0). Electrocardiographic Q-waves were present in 26% of segments with RR-A and in 57% of segments with pattern B. After revascularization, all dyssynergic segments with pattern A showed improved wall motion, while only 40% of segments with pattern B and abnormal wall motion had such improvement. CONCLUSION: Our results suggest that dyssynergic segments with pattern A should be considered viable, while more caution should be used in classifying those with pattern B.

Coronary Angiography↗

PubMed1995

Correlative morphologic and functional imaging for diagnosis, staging and follow up in AIDS: an overview.

The immunocompromised patient can be affected by different opportunistic infections and tumors, that can involve all organ systems, and particularly, the central nervous system, the respiratory system, the gastrointestinal tract. The extreme variability of AIDS presentations requires a specific preparation and cooperation between the different diagnostic imaging specialists and a close collaboration with the clinicians. With AIDS, different morphologic and functional imaging techniques can be used for detection of disease sites, assessment of the extent of the disease and monitoring of disease changes over time and response to treatment. The complexity of AIDS presentations is such that full integration of the complementary information obtained with different techniques could be most useful. Image registration (coregistration, fusion) indicates approaches where precise spatial cross-references are obtained, in order to combine the information acquired with different imaging modalities, in particular by blending morphologic CT/MRI data with functional SPET/PET data. In this paper, an overview of the developments in the field of "image fusion" follows some comments on the results of morphologic and functional assessment of brain, chest and abdominal diseases in the course of AIDS, as illustrative examples of the potential benefits of multimodality image correlation.

AIDS-Related Opportunistic Infections↗

PubMed1995

Detecting deep venous thrombosis with technetium-99m-labeled synthetic peptide P280.

UNLABELLED: Scintigraphy, using small, thrombus-avid, synthetic peptides labeled with gamma-emitting nuclides is an innovative approach to the noninvasive detection of acute deep venous thrombosis (DVT). The goal of this study was to evaluate clinically 99mTc-P280 for imaging DVT. The peptide P280 is a 26 amino acid dimer that binds with high affinity to the GPIIb/IIIa receptor expressed on activated platelets and can be labeled with 99mTc. METHODS: Scintigraphy with 99mTc-P280 (10-22 mCi) was performed in nine patients with clinical suspicion and diagnostic evidence of DVT. Planar and tomographic images of the legs, abdomen/pelvis, chest and head were obtained immediately, 1, 2, 4 and 24 hr after injection. RESULTS: No adverse effects were noted after 99mTc-P280 administration in any patient. Positive visualization of thrombi occurred in eight of nine cases with confirmed DVT within 1 hr of tracer injection. The majority of the patients had recent onset of DVT symptoms (less than 3 wk), while the only negative case was diagnosed 42 days earlier and was likely related to an accident 7 mo earlier. Thrombi-to-background ratios were essentially constant over the study. Technetium-99m-P280 accumulation was also discernible in two patients with pulmonary embolism, while in a third patient the radiotracer concentrated in a cerebellar hemangioblastoma. CONCLUSION: These human studies indicate that 99mTc-P280 is a potentially safe and sensitive procedure for diagnosing DVT and pulmonary embolism. It also may have substantial utility in monitoring active venous thrombosis.

Adult↗

PubMed1995

[Morpho-functional diagnostic imaging in the assessment of viable myocardium in patients with ischemic heart disease. Correlations between myocardial perfusion and regional function of the left ventricle].

Forty patients (38 men and 2 women, mean age 56 +/- 9 years) with angiographic evidence of coronary artery disease underwent 201Thallium myocardial scintigraphy and two-dimensional echocardiography. 201Thallium uptake and echocardiographic regional ventricular function were studied in corresponding myocardial segments. On exercise-redistribution 201Thallium imaging, 308 segments (51% of the total) had normal Thallium uptake, 48 (8%) exhibited reversible defects and 244 (41%) irreversible defects. Of the latter 244 segments with irreversible defects, 114 (47%) exhibited increased tracer uptake (Re+) and 130 (53%) remained unchanged (Re-) after 201Thallium reinjection at rest. Regional ventricular function was significantly better in the segments with normal Thallium uptake than in the segments with reversible or irreversible defects (p < 0.001). Furthermore, the segments with irreversible defects Re- had impaired regional function compared to the segments with irreversible defects Re+ (p < 0.001). Coronary artery stenosis was significantly more severe in the segments with irreversible defects Re- (93 +/- 16%) than in those with reversible defects (81 +/- 20%) and with irreversible Re+ defects (80 +/- 20%) (both p < 0.001). In conclusion, in coronary artery disease patients, exercise-redistribution 201Thallium cardiac imaging with reinjection at rest can identify severely ischemic but still viable myocardium and may be particularly useful in the prognosis of such patients.

Adult↗

PubMed1995

Ambulatory monitoring of left ventricular function during cardiopulmonary exercise tests in normal sedentary subjects.

UNLABELLED: Ambulatory monitoring (VEST) of left ventricular (LV) function is a useful and accurate method to measure cardiac function during exercise and rest. The aim of this study was to evaluate LV response to exercise in normal sedentary subjects. METHODS: Ten normal sedentary subjects underwent continuous ambulatory monitoring of LV function by VEST during upright bicycle exercise associated with combined analysis of pulmonary gas exchange. All parameters of LV function were measured in control conditions at rest, at the anaerobic threshold (point of nonlinear increase in ventilation relative to oxygen uptake) and at peak oxygen uptake (peak VO2). RESULTS: Heart rate and cardiac output significantly increased from control conditions to anaerobic threshold (p < 0.001) and from anaerobic threshold to peak VO2 (p < 0.001). Ejection fraction, end diastolic volume and stroke volume significantly increased from control conditions to anaerobic threshold (p < 0.001), showing no significant change from anaerobic threshold to peak VO2. Finally, end-systolic volume significantly decreased from control conditions to anaerobic threshold (p < 0.001), showing no significant change from anaerobic threshold to peak VO2. CONCLUSION: VEST is particularly useful in the evaluation of cardiac response to exercise in normal sedentary subjects, providing a better understanding of the spectrum of the normal LVEF response to exercise. Our data demonstrate that ejection fraction response to exercise is variable after anaerobic threshold, and a uniform increase is not necessarily expected in normal sedentary subjects.

Adult↗

PubMed1995

Technetium-99m-methylene diphosphonate scintimammography to image primary breast cancer.

UNLABELLED: Technetium-99m-methylene diphosphonate (MDP) uptake within breast lesions was investigated during routine presurgical bone scintigraphy in a cohort of women at high risk for cancer who were candidates for surgery or excisional biopsy. The aim was twofold: (a) to demonstrate positive 99mTc-MDP uptake in primary breast cancer and (b) to differentiate malignant from benign lesions. METHODS: Anterior and oblique lateral views of the breasts were acquired 0-4 min, 10-20 min and 2 hr after intravenous injection of 740 MBq of 99mTc-MDP in 200 women with elevated suspicion or proven diagnosis of breast cancer (Group 1) and in 80 women with other solid tumor types (Group 2). RESULTS: Physical examination and mammography revealed breast abnormalities in all Group 1 subjects. The mammographic findings were definitely positive for carcinoma in 120 patients, highly suspicious in 27 and indeterminate in 53. Breast cancer was later histologically diagnosed in 172 women (86%) and benign disease found in 28 women (14%). Of these patients, 158 (92%) showed focal uptake of 99mTc-MDP in the images collected 10-20 min after injection. This was found to be the best timing for imaging, with tumor-to-background ratios as high as 4.3 (mean +/- s.d. = 3.8 +/- 0.4). Two hr after injection, only 61 of the 158 (38%) malignant lesions were clearly detectable. CONCLUSION: Technetium-99m-MDP is concentrated by primary breast carcinoma 10-20 min after injection, enabling successful external gamma imaging. Scintimammography with 99mTc-MDP is an accurate test that differentiates malignant from benign breast lesions, particularly in patients with indeterminate mammograms.

Adult↗

PubMed1995

Technetium-99m-tetrofosmin regional myocardial uptake at rest: relation to severity of coronary artery stenosis in previous myocardial infarction.

UNLABELLED: The aim of this study was to assess the potential role of 99mTc-tetrofosmin cardiac tomography in detecting totally occluded or severely stenosed coronary arteries. METHODS: Thirty-three patients (32 men, 1 woman; mean age, 52 +/- 9 yr) with chronic coronary artery disease (CAD) and left ventricular dysfunction (ejection fraction 40% +/- 12%) underwent resting 99mTc-tetrofosmin SPECT and coronary arteriography within 2 wk. Regional distribution of 99mTc-tetrofosmin activity was compared with the coronary anatomy. Tracer uptake was quantitatively analyzed in 22 segments for each patient. The activity in each segment was expressed as a percent of the peak activity. RESULTS: A significant relationship between the degree of coronary artery stenosis and 99mTc-tetrofosmin uptake was observed (p = -0.64, p < 0.001). Technetium-99m-tetrofosmin uptake was lower (p < 0.001) in segments with 100% coronary occlusion with poor collateral flow (53% +/- 17%) compared to segments supplied by a vessel with 50%-99% coronary stenosis (75% +/- 20%) or a normal noncritically stenosed artery (85% +/- 10%). Furthermore, 99mTc-tetrofosmin uptake was lower (p < 0.01) in segments with 100% coronary occlusion with poor (53% +/- 17%) compared to those with good collateral flow (70% +/- 20%). CONCLUSION: These results demonstrate that quantitative analysis of resting 99mTc-tetrofosmin regional uptake detects the majority of segments supplied by occluded coronary arteries with poor collateral flow and suggest that this tracer may be helpful in the diagnosis of acute myocardial infarction.

Adult↗

PubMed1995

Impaired left ventricular diastolic filling in patients with acromegaly: assessment with radionuclide angiography.

UNLABELLED: Acromegaly is associated with increased cardiac morbidity and mortality, but it is not clear whether this is the result of a specific disease of heart muscle or of increased incidence of hypertension. METHODS: Twenty-six patients with acromegaly (11 male and 15 female, mean age 45 +/- 13 yr) and 15 and 12 age- and sex-matched normal controls underwent high temporal resolution radionuclide angiography and two-dimensional echocardiography at rest. RESULTS: Normal controls and patients with acromegaly did not differ with respect to heart rate, ejection fraction, time to end systole, peak ejection rate (PER) and time to PER. In contrast, peak filling rate (PFR), normalized to end diastolic volume (EDV), or stroke volume (SV), or expressed as the ratio of PFR-to-PER was reduced (p < 0.01), time to PFR (TPFR) was prolonged (p < 0.01), and echocardiographic left ventricular mass index was higher (p < 0.001) in patients with acromegaly compared to normals. Patients with acromegaly were divided in normotensives (group 1, n = 17) and hypertensives (group 2, n = 9). Although left ventricular mass index was significantly (p < 0.01) higher in group 2 compared to group 1, PFR and time to PFR were not different between the two groups of acromegalic patients. In the entire group of patients with acromegaly significant relationships between left ventricular mass index and EDV/s (r = -0.56, p < 0.01), SV/s (r = -0.73, p < 0.001), and PFR/PER (r = -0.61, p < 0.001) were observed. CONCLUSION: Patients with acromegaly have impaired left ventricular diastolic filling at rest related to greater left ventricular mass index even in the absence of systemic hypertension.

Acromegaly↗

PubMed1995

Technetium-99m-tetrofosmin imaging of differentiated mixed thyroid cancer.

This report describes the accurate localization of metastatic lesions in a patient with differentiated mixed thyroid cancer using 99mTc-tetrofosmin imaging. A 66-yr-old women with a cytological diagnosis of follicular thyroid cancer associated with a large amount of goiter changes was studied by 99mTc-tetrofosmin total-body scintigraphy. No significant tetrofosmin uptake was observed in the thyroid nodules, which mainly showed goiter abnormalities. Abnormal increased tetrofosmin uptake, however, was found in metastatic tumor lesions located in the cervical and dorsal spine as well as in the left lower chest wall and lungs. In conclusion, 99mTc-tetrofosmin, a new radiopharmaceutical proposed for myocardial perfusion imaging, may be useful in patients with thyroid cancer.

Aged↗

PubMed1995

[The short- and medium-term ambulatory radionuclide study of left ventricular function (VEST) after aortocoronary bypass].

The aim of the present study was to evaluate the variation in left ventricular function at 15 and 120 days after bypass surgery. Ten male patients (mean age 59.6 +/- 7 years) with previous myocardial infarction and coronary stenosis of at least two main vessels, underwent a radionuclide ambulatory monitoring of left ventricular function (VEST) during: handgrip test, mental stress test, walking, climbing stairs. These tests were carried out 8 +/- 2 days before (T0), 15 +/- 3 days (T1) and 120 +/- 11 days after coronary bypass; heart rate (HR), ejection fraction (EF), stroke volume (SV), and cardiac output (CO) were evaluated beat by beat before and during the test until the maximal HR was reached. Handgrip and mental stress tests did not induce significant variations in cardiac indices both before and after cardiac surgery. No variation in HR was observed before and after the test. During walking, at T0, HR increased from rest to maximal effort (p < 0.01) with a significant decrease in EF (p < 0.05); at T1 HR, EF, SV and CO increased with respect to rest (p < 0.01); AT T2 HR, EF (p < 0.05) and CO (p < 0.01) increased with respect to rest. Climbing stairs, at T0, HR increased (p < 0.01) and EF decreased (p < 0.05); at T1 HR, EF, CO (p < 0.05) and SV (p < 0.01) increased with respect to rest. At T2 an increase in HR (p < 0.01) and CO (p < 0.05) was observed at maximal effort with respect to rest. The statistical analysis on the percentage variations between baseline and maximal effort (climbing stairs) showed a significant increase in SV at T2 compared to T0 (p < 0.01). In conclusion, VEST during daily normal activities 15 days and 4 months after bypass surgery showed a significant increase in cardiac function indices. The best results obtained at T1 can be explained with the transient increase in adrenergic tone at the time of early postoperative period.

Aged↗

PubMed1995

[Scintigraphic characterization of expansive lesions located in the adrenals. Comparison with magnetic resonance imaging].

In this study, 35 patients (11 men and 24 women, mean age 47 +/- 16 years) with unilateral adrenal masses underwent nor-cholesterol (nor-Chol) (n = 11), metaiodobenzylguanidine (MIBG) (n = 15) or nor-Chol and MIBG (n = 9) radionuclide studies. In all patients Magnetic Resonance (MR) adrenal imaging was also performed. In 19 (54%) patients, no laboratory abnormalities of adrenal function were observed. In the other 16 (46%) patients, adrenal hyperfunction was found. In 21 lesions, histology showed 10 pheochromocytomas (Pheos), 6 adenomas, 3 metastases, 1 cyst and 1 nodular focal liver hyperplasia. In the remaining 14 lesions, increased cortisol (n = 4) or aldosterone (n = 2) levels and/or intense nor-Chol uptake (n = 14) were considered suggestive of adenoma. Diagnostic accuracy of both nor-Chol and MIBG radionuclide studies in correctly identifying adenoma or Pheos was 100%. Conversely, qualitative MR signal intensity (SI) analysis on T2-weighted images did not allow to accurately distinguish lesions of different nature. In particular, 10 Pheos, 8 adenomas, 3 mestastasis and 1 cyst clearly showed on T2-weighted images higher SI than the liver; 5 adenomas had a slight higher SI; the remaining lesions (7 adenomas and 1 liver hyperplasia) exhibited low SI. In conclusion, adrenal scintigraphy using nor-Chol or MIBG allows to identify adenomas and Pheos, respectively. Conversely, qualitative MR SI analysis cannot differentiate different adrenal lesion (Pheos, adenoma, metastasis and cyst) and yields heterogeneous results in adenomas.

3-Iodobenzylguanidine↗

PubMed1995

[Imaging of thromboembolism by scintigraphy with the 99m-technetium-labelled synthetic peptide P280].

P280, a synthetic peptide composed of 26 aminoacids, has high affinity (Kd = 100 nM) and specificity for the glycoprotein IIb/IIIa (GPIIb/IIIa) receptor expressed on activated platelets. In this study we investigated the potential usefulness of imaging deep vein thrombosis (DVT) and pulmonary embolism (PE) in humans with 99mTc-P280. In 15 patients (9 men and 6 women; mean age +/- s.d.: 49.2 +/- 14.1) with known DVT and/or PE, serial images were acquired within 24 hours of the injection of approximately 200 micrograms of P280 radiolabelled with 10-23 mCi of 99mTc. P280 was labelled with the ligand exchange method using 99mTc-glucoheptonate. Rapid blood clearance (< or = 5% ID was still circulating in 1 hour) enabled identification of thrombi as early as 60 minutes after the injection, with significant thrombi-to-background ratios (range: 2-4) in 11/15 patients (73%), in 7/9 with DVT, in 2/3 with PE and in 2/3 patients with both DVT and PE. Radiotracer uptake was clearly detectable also in late scans, which confirms that 99mTc-P280 specifically binds to the thrombi through a receptor-mediated mechanism. PE localizations were detectable 3-4 hours after peptide injection, and in 2 cases SPECT enabled the detection of thrombi missed on planar views. Conversely, the test was negative in 4 patients who had the onset of clinical symptoms and the diagnosis of DVT and/or PE more than 40 days before scintigraphy. The lack of 99mTc-P280 uptake in the latter patients suggested that the peptide does not bind to thrombi when thrombogenesis is not active. These preliminary results clearly indicate scintigraphy with 99mTc-P280 to be a suitable, noninvasive and highly specific tool to image fresh clots causing DVT and/or PE. Thus, this technique might overcome the limitations of the imaging procedures currently in use.

Adult↗

PubMed1995

111In-pentetreotide scintigraphy in the post-thyroidectomy follow-up of patients with medullary thyroid carcinoma.

Local and lymphnodal recurrences of medullary thyroid carcinoma (MTC) in thyroidectomy patients with elevated plasma levels of calcitonin and/or CEA can be detected using 111In-pentetreotide (Octreoscan: OCT) scintigraphy, although the sensitivity of this technique in localizing an intrathyroid recurrence of tumor is affected by the low target/non-target uptake ratio. The survival rate of patients with MTC, who have undergone thyroidectomy and who show evidence of a rise in plasma levels of calcitonin and/or CEA is closely linked to the number and localization of the metastases. However the role of conventional imaging techniques (X-rays, US, CT, and MR) in the follow-up after thyroidectomy is controversial. Numerous radiocompounds are currently being used to detect local and distant recurrences of MTC. The present study evaluated OCT and pentavalent 99mTc-dimercapto-succinic-acid (99mTc-DMSA-V) scintigraphy performed in 13 patients with a histologic diagnosis of MTC and in one with MEN 2A, all of whom had undergone thyroidectomy between 3 months and 15 years before. The patients also underwent 123I (NaCI) scintigraphy to evaluate the sites and extension of thyroidal remnants. 111In-pentetreotide scintigraphy was positive in 9/14 patients (64%); the 99mTc-DMSA-V was positive in 5/14 patients (35%). 111In-pentetreotide scintigraphy recognized 18 sites of abnormal uptake (12 in the neck); 9mmTc-DMSA-V detected 9 MTC recurrences in the same patients. In conclusion, 111In-OCT scintigraphy represents, in the authors' experience, a useful method, more sensitive than 9mmTc-DMSA-V, to detect MTC recurrences in patient follow-up post-thyroidectomy.

Adult↗

PubMed1995

Comparison of labeled MIBG and somatostatin analogs in imaging neuroendocrine tumors.

In 10 patients with histologically proven neuroendocrine tumors (4 carcinoids, 4 pheochromocytomas, 1 medullary thyroid cancer and 1 Merkel tumor) the results of radiolabeled metaiodobenzylguanidine (MIBG) and somatostatin analogs were compared. A total of 24 tumor lesions was detected on standard imaging studies. MIBG scintigraphy correctly localized 12 (50%) of these lesions which were observed in 5 patients (4 with pheochromocytoma and 1 with carcinoid tumor). Scintigraphy using labeled somatostatin analogs correctly localized 21 (87%) lesions which occurred in 8 patients (4 with carcinoid, 2 with pheochromocytoma, 1 with medullary thyroid cancer and 1 with Merkel tumor). Concordant scintigraphic results were obtained in 1 patient with carcinoid and 2 with pheochromocytoma. In conclusion, although this series was limited, our results suggest that MIBG is more accurate than somatostatin analogs in imaging pheochromocytoma. Conversely, somatostatin analogs are more accurate than MIBG in detecting other neuroendocrine tumors such as carcinoids.

3-Iodobenzylguanidine↗