RESUMO
Modification of the Bücherer-Strecker amino acid synthesis facilitated the production of DL-[11C]tryptophan and DL-[11C]valine for clinical trials in patients with proven or suspected pancreatic disease. Examples of rectilinear scans and tomographic images of the pancreas are presented in this initial paper. Positron computed tomography was done with the ORTEC ECAT system. Rapid localization of these C-11-labeled amino acids and fast clearance from the plasma permit almost immediate examination following i.v. injection. Illustrative images include the normal pancreas, pancreatitis, and pancreatic carcinoma. The use of positron tomobraphy with C-11-labeled DL-tryptophan and DL-valine appears to offer a new and promising diagnostic modality for the detection and study of pancreatic diseases.
Assuntos
Pâncreas/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Pancreatite/diagnóstico por imagem , Tomografia Computadorizada de Emissão/métodos , Triptofano/metabolismo , Valina/metabolismo , Radioisótopos de Carbono , Humanos , Injeções Intravenosas , Pâncreas/metabolismo , Selenometionina , Fatores de TempoRESUMO
High specific activity [11C] Carboxyl-labeled 1-aminocyclopentane-carboxylic acid ([11C] ACPC) was tested as a tumor-scanning agent in thirty-eight patients. This artificial amino acid clears the blood to a level of less than 12% within 45 min; thus, imaging is possible within the useful life of C-11. [11C] ACPC can be produced in amounts adequate for clinical scanning. Doses between 12 and 45 mCi were given by i.v. injection, and scans obtained only in the single-photon mode gave clinical information on the sites of tumors. There was no evidence of any toxic effects from [11C] ACPC, and the radiation doses as extrapolated from animal data are approximately 0.01 rad per mCi for the whole body and less than 0.06 rad per mCi for the pancreas. In all but five of the 38 patients [11C] ACPC scans were compared with those obtained with Ga-67 citrate. There were 19 positive [11C] ACPC scans and 24 positive Ga-67 scans. The results indicate that [11C] ACPC is likely to be of diagnostic value for cancer patients if used in conjunction with positron tomography instrumentation.
Assuntos
Aminoácidos , Radioisótopos de Carbono , Cicloleucina , Neoplasias/diagnóstico por imagem , Cicloleucina/efeitos adversos , Cicloleucina/metabolismo , Partículas Elementares , Feminino , Humanos , Marcação por Isótopo , Masculino , Neoplasias/metabolismo , Doses de Radiação , Cintilografia , Fatores de TempoRESUMO
Eight patients with proven or suspected neoplastic lesions were examined with 1-aminocyclobutane C-11-carboxylic acid and 1-aminocyclopentane C-11-carboxylic acid using positron emission computed tomography. The results of this comparative study have shown that both of these unnatural amino acids have a high affinity for malignant tumors. The potential of nonmetabolizable C-11-labeled amino acids as noninvasive indicators of metabolic tumor activity is demonstrated and discussed.