Seminars in nuclear medicine
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Head trauma affects thousands of people every year. Neuroimaging techniques provide some of the most important diagnostic, prognostic, and pathophysiological information in the management of brain injury. ⋯ Functional imaging has been shown to be helpful in assessing the areas of the brain affected by the trauma as well as determining long term prognosis and rehabilitation potential. This article will review the current uses of neuroimaging techniques in head trauma and delineate future applications.
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Review Case Reports
Neuroimaging in cerebrovascular disorders: measurement of cerebral physiology after stroke and assessment of stroke recovery.
Nuclear medicine imaging can play an important role in the diagnosis of stroke risk, the differential diagnosis of vascular and parenchymal cerebral abnormalities, and the understanding and management of poststroke recovery. Radionuclide brain-imaging methods can assess hemodynamic, vascular, and metabolic status before and after stroke. Several techniques, including vasodilatory stress imaging with regional cerebral blood flow (rCBF) single-photon emission computed tomography (SPECT), oxygen extraction methods with positron emission tomography (PET), and spectroscopic imaging with magnetic resonance spectroscopic imaging, offer ways to distinguish vascular from parenchymal dysfunction and to determine whether any observed abnormalities in cerebral blood flow are primary or secondary disease manifestations. ⋯ The phosphocreatine-adenosine triphosphate ratio was highly correlated (r = 0.88, P <.05) with increasing (18)F-fluorodeoxyglucose uptake. These results showed that there is a parallel change in glucose metabolism and high-energy phosphate metabolism associated with poststroke recovery that is proposed to be due to cerebral reorganization in the contralateral premotor cortex. The value of these results on rehabilitation strategy, including possible criteria for the use of facilitatory versus compensatory approaches, is analyzed.
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Review
The natural history of venous thromboembolism: impact on ventilation/perfusion scan reporting.
Deep vein thrombosis (DVT) and pulmonary embolism (PE) are separate but related aspects of the same dynamic disease process known as venous thromboembolism (VTE). Recent community studies have shown that VTE is a major health issue for the developed world, with at least 201,000 new cases each year in the United States, comprising 107,000 with DVT and 94,000 with PE. A quarter of PE cases die within 7 days, some so rapidly that treatment or intervention is impossible. ⋯ Diagnostic tools or checklists can be used as an alternative. A general knowledge of the natural history of VTE will encourage the nuclear medicine physician to provide an appropriate clinical signal to complement VQ categorical analysis. Combination of these 2 dynamic elements of the art and science of VQ scan reporting-the clinical pretest probability of PE and lung scan category-will permit an accurate prediction of the absolute risk of PE posttest.
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Review
Somatostatin receptor-targeted radionuclide therapy of tumors: preclinical and clinical findings.
In preclinical studies in rats we evaluated biodistribution and therapeutic effects of different somatostatin analogs, [(111)In-DTPA]octreotide, [(90)Y-DOTA,Tyr(3)]octreotide and [(177)Lu-DOTA,Tyr(3)]octreotate, currently also being applied in clinical radionuclide therapy studies. [Tyr(3)]octreotide and [Tyr(3)]octreotate, chelated with DTPA or DOTA, both showed high affinity binding to somatostatin receptor subtype 2 (sst(2)) in vitro. The radiolabelled compounds all showed high tumor uptake in sst(2)-positive tumors in vivo in rats, the highest uptake being reached with [(177)Lu-DOTA,Tyr(3)]octreotate. In preclinical therapy studies in vivo in rats, excellent, dose dependent, tumor size responses were found, responses appeared to be dependent on tumor size at therapy start. ⋯ Minor CT-assessed tumor shrinkage (25% - 50% reduction) was noticed in 6% of 18 patients and partial remission (50% - 100% reduction, SWOG criteria) in 39%. Eleven percent of patients had tumor progression and in 44% no changes were seen. These data show that radionuclide therapy with radiolabelled somatostatin analogs, like [DOTA, Tyr(3)]octreotide and [DOTA, Tyr(3)octreotate is a most promising new treatment modality for patients who have sst(2)-positive tumors.
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Multicenter Study Clinical Trial
In- and Y-DOTA-lanreotide: results and implications of the MAURITIUS trial.
The high-level expression of somatostatin receptors (SSTR) on various tumor cells has provided the molecular basis for successful use of radiolabeled peptide analogues as tumor tracers in nuclear medicine. The vast majority of human tumors seem to overexpress one or the other of 5 distinct hSSTR subtype receptors. Whereas neuroendocrine tumors frequently overexpress human(h) SSTR2, intestinal adenocarcinomas frequently express hSSTR3 or hSSTR4, or both of these hSSTRs. ⋯ In conclusion, preclinical data and clinical studies confirm the potential usefulness of radiolabeled lanreotide for tumor diagnosis and therapy. However, careful consideration of the type of radiotracer used for receptor-mediated therapy should be made for the individual patient. Whole-body dosimetry should always be performed to predict doses for tumors and the critical organs, which are kidney and bone marrow.