Developing nuclear medicine in developing countries: IAEA's possible mission.
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Developing Countries↗
Biomedical subjects
Maurizio Dondi
Publications and source records attributed to Maurizio Dondi.
Significance of posture and workload in exercise renography.
BACKGROUND: Exercise-induced alteration in renal function has been described in patients with essential hypertension. The aim of our study was to assess the significance of adopting a supine posture and the degree of workload required to induce these changes in patients with essential hypertension. The second aim was to assess whether the severity of hypertension had any influence on the development of exercise related renal dysfunction. MATERIAL AND METHODS: Fifteen patients were studied (nine patients with mild and untreated hypertension and six patients with drug resistant hypertension). Exercise renography was carried out using a cycloergometer with the patient lying in supine posture and a target exercise rate of 20 bpm over baseline rate. Each patient was injected with 100 MBq of 99mTc-MAG3 and renography was carried out for 20 minutes. Renography was repeated in rest condition only when an abnormality was observed in exercise scans. RESULTS: Exercise renography was normal in 12 patients, while in 3 patients minor abnormalities were observed during exercise related to a minimal degree of pelvic dilatation. These changes remained substantially unmodified at rest. In none of the 15 patients did we find positive studies (i.e. reversible exercise induced prolongation of tracer transit caused by cortical retention). There was no difference in the results between patients with mild or severe hypertension. CONCLUSIONS: Our results are different from previous reports on exercise renography since different groups have demonstrated exercise-induced renal dysfunction in the majority of patients with essential hypertension. The main differences between our protocol and that adopted in the literature relate to posture during exercise (upright vs. supine) and degree of workload (minor in supine exercise with less workload). These differences may have contributed to our results but further and larger studies are required to address the pathophysiological basis of exercise-induced alteration in renal function in association with essential hypertension.
Adult↗
Noninvasive dynamic assessment with transthoracic echocardiography of a composite arterial Y-graft achieving complete myocardial revascularization.
BACKGROUND: Composite arterial grafts are increasingly used in coronary artery bypass surgery. We assessed with transthoracic echocardiography the composite radial artery and in situ left internal thoracic artery Y-graft. METHODS: In 53 of 60 consecutive patients who underwent complete myocardial revascularization using only this composite arterial graft, good transthoracic echocardiographic images and pulsed Doppler signals of the Y-graft main stem were obtained at rest and early after standard exercise. Stress/rest 99mTc-sestamibi myocardial perfusion single-photon emission computed tomography (SPECT) was the gold standard for residual myocardial ischemia. The patients with negative SPECT were divided into groups according to the number of coronary artery systems grafted, and history of preoperative myocardial infarction. RESULTS: Diastolic peak velocity, diastolic velocity-time integral, the diastolic-to-systolic ratio of the peak velocities and velocity-time integrals, and the stress-to-rest ratio of the diastolic peak velocities and diastolic velocity-time integrals in the negative-SPECT patients were significantly greater than in the 6 positive-SPECT patients. Sensitivity and specificity for ischemia of the stress-to-rest ratio of the diastolic peak velocities less than 1.5 were 100%. The stress-to-rest ratio of the diastolic velocity-time integrals in the patients with three coronary systems grafted, and in those without preoperative myocardial infarction, were respectively greater than in the patients with two systems grafted (p < 0.0001), and in those with preoperative myocardial infarction (p = 0.0048). CONCLUSIONS: Noninvasive dynamic assessment with transthoracic echocardiography of a composite arterial graft, including in situ left internal thoracic artery, is feasible and correlates with myocardial perfusion SPECT. The Y-graft used was able to regulate its flow capacity to myocardial demand.
Adult↗
Assessing dopaminergic function in Parkinson's disease: levodopa kinetic-dynamic modeling and SPECT.
Levodopa pharmacokinetic-phamacodynamic (PK-PD) modeling may be able to test the functional integrity of the nigrostriatal dopaminergic system in Parkinson's disease (PD). [(123)I]-FP-CIT SPECT imaging of striatal dopamine transporters has also been introduced for the evaluation of presynaptic dopaminergic homeostasis. We aimed to assess the intrapatient relation between levodopa PK-PD and SPECT measures of dopaminergic function in PD. Thirty-five PD patients, 1 to 4 on the Hoehn and Yahr (H&Y) scale, enrolled in the study. Each patient was examined by levodopa PK-PD modeling and SPECT imaging. Primary measure outcomes were the levodopa half-life in the effect compartment (t1/2(eq)) for PKPD modeling and the ratio of specific to non specific (SP/NSP) tracer striatal uptake for SPECT. Levodopa t1/2(eq) was highly significantly correlated with H&Y scale (r = -0.815, p < 0.0001), Unified Parkinson's disease Rating Scale (UPDRS) (r = -0.691, p < 0.0001) and PD symptom duration (r = -0.647, p < 0.0001). SPECT contralateral putamen SP/NSP ratio showed the most significant correlations with clinical indicators of disease severity: H&Y, r = -0.526, p < 0.002; UPDRS, r = -0.523, p < 0.002; symptom duration, r = -0.513, p < 0.002. Significant correlations were observed between levodopa t1/2(eq) and putamen SP/NSP ratios, yielding the closest correlation for the contralateral region (r = 0.522, p < 0.002). An indirect PK-PD dopaminergic functional variable and direct SPECT measures of presynaptic dopaminergic system homeostasis were in close agreement with clinical data and correlated to each other. Levodopa PK-PD modeling can be a practical clinical tool indirectly assessing the functional integrity of the nigrostriatal dopaminergic system in PD patients.
Antiparkinson Agents↗
Somatostatin receptor (SSTR) scintigraphy in patients with osteosarcoma.
To investigate somatostatin receptors (SSTRs) in primary or metastatic high-grade osteosarcoma, 18 patients (12 without metastases, 4 with synchronous lung, and 2 with metachronous bone metastases) underwent SSTR scintigraphy. After intravenous (i.v.) injection of 200-250 MPq of 111In-pentreotide, images were recorded at 4 and 24 hours. All patients underwent 99mTc-methylene diphosphonate (MDP) bone scan (BS). Scans were interpreted both with qualitative evaluation and with semiquantitative image processing, by means of tumor-to-background ratio modification over time. Primary tumor: SSTR scintigraphy was positive in 12 (75%) patients: 10 (83%) of the 12 nonmetastatic patients, and 2 (50%) of those with synchronous metastases. Metastases: SSTR scintigraphy was positive only in one (17%) of the six patients with metastatic disease. No relation was found between SSTR scintigraphy results and gender, histologic subtype, site, and size of the tumor. After primary chemotherapy, 15 patients underwent surgery of primary tumor; a good histologic response was found in 7 (64%) of the 11 patients with positive SSTR scintigraphy versus 1 (25%) of the 4 patients with negative SSTR scintigraphy. High-grade osteosarcoma exhibits somatostatin receptors, usually detectable in the primary tumor, but not in the metastatic lesions. The different expression of somatostatin receptors observed in primary and metastatic lesions, and in patients with tumors having different chemosensitivity, could indicate a possible relation between somatostatin receptors and biological behavior of the tumor.
Adolescent↗
Non-invasive assessment of the composite radial artery and in situ left internal thoracic artery Y-graft for myocardial revascularization.
BACKGROUND: It is controversial whether composite arterial grafts can provide adequate blood flow for myocardial revascularization. We assessed at transthoracic echography and myocardial scintigraphy the composite radial artery-in situ left internal thoracic artery Y-graft. METHODS: In 32 of 36 consecutive patients who underwent myocardial revascularization using this composite arterial graft, successful postoperative transthoracic images of the main stem of the Y-graft were obtained at rest and early after standard exercise. The main stem diameter, cross-sectional area and blood flow velocity and volume were measured. The coronary flow reserve (CFR) was calculated. The patients were divided into three groups according to the number of coronary artery systems bypassed with the Y-graft: group I included 11 patients with one coronary system bypassed, group II 18 patients with two, and group III 3 patients with three coronary systems bypassed. In 14 patients myocardial scintigraphy was performed at rest and after stress. RESULTS: After exercise, the diameter, cross-sectional area, and blood flow velocity and volume increased. The mean CFR in group III was greater than in group I (p = 0.00045) and in group II (p = 0.049). In 2 patients, the nuclear stress test was positive (reversible ischemia in the distribution area of the Y-graft) and the mean CFR was lower than in the patients with a negative nuclear stress test (p = 0.046). CONCLUSIONS: This composite arterial graft is a compliant conduit, able to regulate its flow capacity to myocardial demand. Non-invasive assessment of this Y-graft using transthoracic echography is possible, and correlates with the results of myocardial scintigraphy.
Adult↗
Exercise renal scintigraphy shows renal ischemia in a transplanted kidney.
Exercise renography is essentially a research method to investigate hypertension and has very limited clinical application. Captopril renography has long been used to study renal artery stenosis causing hypertension with good results. The authors describe a patient with a transplanted kidney supplied by reversal of flow via the external iliac artery. A "steal phenomenon" of the kidney related to ambulation was considered likely. Ischemia of the transplanted kidney was revealed by exercise renography, which showed parenchymal trapping of radiotracer as a result of exercise.
Exercise Test↗
Dopamine transporter gene polymorphism, spect imaging, and levodopa response in patients with Parkinson disease.
OBJECTIVES: To assess the potential association between dopamine transporter (DAT) genotype, single photon emission CT (SPECT) measures using [123I]-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodophenyl)nortropane ([123I]-FP-CIT) of striatal dopaminergic function, and oral levodopa response pattern in a cohort of patients with Parkinson disease. METHODS: Thirty-six patients at different disease stages enrolled in the study. Each patient was examined by [123I]-FP-CIT SPECT and a standardized oral levodopa test on 2 separate days in a randomized order within 3 weeks. The main outcome variables were the specific-to-nonspecific tracer uptake ratio in the contralateral putamen for SPECT analysis; latency, duration, and magnitude of the motor effect; and presence of dyskinesias for the levodopa test. The variable number of tandem repeat (VNTR) polymorphisms of the gene coding for DAT were detected for each patient by standard methods. RESULTS: Contralateral putamen [123I]-FP-CIT uptake ratios were similar in the patients carrying the 9-copy allele (n=20) of the DAT VNTR compared with 10-repeat homozygotes (n=16). No significant difference was found in levodopa main outcome variables and dyskinesia incidence between the two groups of patients stratified by DAT VNTR polymorphism. CONCLUSIONS: The study did not identify clinically relevant in vivo DAT neurochemical function phenotypes or levodopa response patterns associated with the DAT polymorphism.
Aged↗