ABSTRACT
OBJECTIVES: Gastroenteropancreatic neuroendocrine tumors (NETs) are cancers originating from neuroendocrine organs such as the pancreas, pituitary, thyroid, and adrenal glands and tumors arising from the diffuse neuroendocrine cells that are widely distributed throughout the body. NETs express somatostatin (SS) and contain a high density of SS receptors; therefore, they can be specifically targeted with SS-based radiopharmaceuticals. The aim of this research was to determine the validity in terms of specificity, sensitivity, and the agreement beyond chance with the biopsy (gold standard) of the 99mTc-EDDA-HYNIC-Tyr³octreotide (99mTc-TOC) to image and localize NETs and their metastases. MATERIALS AND METHODS: Freeze-dried kits containing 0.0125 mg HYNIC-octreotide and co-ligands were easily labeled and quality controlled within the hospital radiopharmacy. Fifty-six consecutive Mexican patients with a previous presumptive diagnosis of NETs underwent several clinical and laboratory studies and were referred to the Nuclear Medicine Department for a routine scan with 99mTc-TOC. The patients were injected with 500-600 MBq 99mTc-TOC, and whole-body images were obtained 2 h later with a SPECT or a SPECT/CT camera. Two nuclear medicine physicians observed the images and classified them as 17 negative and 39 positive. After correlating the image of each patient with our 'gold standard' (biopsy, clinical history, morphological images, and tumor marker assays), the 99mTc-TOC images were classified by the same two physicians as 12 true negatives, five false negatives, 38 true positives and one false positive. RESULTS: The validity of 99mTc-TOC in terms of relative frequencies with corresponding 95% confidence intervals were as follows: 92.3% (64-100%) specificity; 88.4% (78-97%) sensitivity; and the agreement beyond chance was 73% (60-84%). The positive predictive value was 97.4% (87-100%); the negative predicted value was 70.6% (48-93%); the accuracy was 89.3% (89-97%); and the prevalence was 76.8% (64-87%). CONCLUSION: Because of these high values, we strongly recommend scintigraphy with the Mexican-produced 99mTc-TOC for the localization of NETs and their metastases, and we conclude that it is a good tool for detecting neuroendocrine disease in a Mexican population.
Subject(s)
Digestive System Neoplasms/diagnostic imaging , Multimodal Imaging/methods , Neuroendocrine Tumors/diagnostic imaging , Organotechnetium Compounds , Positron-Emission Tomography , Radiopharmaceuticals , Tomography, Emission-Computed, Single-Photon/methods , Tomography, X-Ray Computed , Adult , Aged , Aged, 80 and over , Digestive System Neoplasms/secondary , Female , Humans , Male , Middle Aged , Neuroendocrine Tumors/secondary , Reproducibility of Results , Sensitivity and Specificity , Whole Body Imaging , Young AdultABSTRACT
UNLABELLED: Fever of unknown origin (FUO) represents a challenge to clinical medicine, and bacterial cultures have been considered the 'gold standard' in discriminating between fevers resulting from bacterial infection and sterile inflammations. In nuclear medicine, a synthetic radiolabeled antimicrobial peptide (Tc-UBI) is used to image the molecular localization of infectious microorganisms. OBJECTIVE: The aim of this research was to determine the absolute and relative frequencies of Tc-UBI, by molecular imaging, to detect infection foci in patients with fever in study or FUO. METHODS: Images (207) from 196 patients with FUO acquired with Tc-UBI and a Siemens gammacamera were read by two nuclear medicine physicians and classified as positive or negative for infection foci. The diagnostic value was corroborated with our gold standard, which comprises bacterial cultures of biopsies, blood and urine, plus laboratory studies, morphological images (radiographs, nuclear magnetic resonance, computed tomography) and the clinical history of each patient. The absolute and relative frequencies of Tc-UBI were calculated from the molecular images versus the gold standard. RESULTS: The specificity of Tc-UBI for localizing infection foci and for discarding sterile inflammation was 95.35%, the sensitivity was 97.52%, the positive predictive value was 96.72%, the negative predictive value was 96.47%, the accuracy was 96.62%, and the observed agreement between the bacterial culture and the molecular image was 96.62% (P=0.0001). CONCLUSION: Considering that the absolute and relative frequencies are very high, we propose that, in the future, Tc-UBI molecular imaging could be the gold standard to detect infection sites and to discard sterile inflammation.
Subject(s)
Bacterial Infections/complications , Bacterial Infections/diagnosis , Fever of Unknown Origin/complications , Organotechnetium Compounds , Peptide Fragments , Adolescent , Adult , Aged , Bacterial Infections/pathology , Biopsy , Diagnosis, Differential , Female , Humans , Inflammation/complications , Inflammation/diagnosis , Male , Middle Aged , Predictive Value of Tests , Sensitivity and SpecificityABSTRACT
Objetivo. Comparar la calidad de las imágenes de gammagrafía ósea obtenidas con un radiofármaco nuevo, el 99mTc-ABP, con aquéllas obtenidas con el 99mTc-MDP. Material y métodos. Fue un estudio comparativo en un mismo sujeto. Se estudiaron 9 voluntarios sanos (5 mujeres y 4 hombres) de 23 a 39 años de edad. A todos se les inyectaron 740 MBq de los radiofármacos Tc-ABP y Tc-MDP con un intervalo de 72 horas entre uno y otro. Dos horas después de cada inyección se les realizó un gammagrama óseo de cuerpo entero con una cámara de centello MultiSpect 2 y se determinaron los parámetros radiofarmacocinéticos. Tres médicos nucleares evaluaron por separado la calidad de las imágenes mediante el trazado de regiones de interés (RDI) sobre vértebras, costillas, esternón, fémur, articulaciones y cráneo. Se obtuvieron relaciones hueso/músculo con RDI sobre diferentes huesos. Los resultados se compararon etadísticamente con las pruebas de kappa y de Wilcoxon. Resultados. La concordancia sobre la calidad de las imágenes de los dos radiofármacos por los tres observadores fue moderada (kappa 0.4). La relación fémur/músculo mostró una distribución normal y no manifestó diferencias significativas entre radiofármacos. Conclusiones. La calidad de las imágenes con ambas preparaciones fue similar. Recomendamos utilizar al 99mTc-ABP en la gammagrafía ósea debido a la menor exposición a radiación del paciente
Subject(s)
Humans , Male , Female , Adult , Alendronate , Bone and Bones , Organotechnetium Compounds , Organotechnetium Compounds/pharmacokinetics , Technetium Tc 99m Medronate , Technetium Tc 99m Medronate/pharmacokineticsABSTRACT
Describimos el caso de una niña de 8 años de edad con epilepsia parcial continua (EPC) con sacudidas clónicas del hemicuerpo izquierdo y con deterioro neurológico progresivo. Los tratamientos antiepilépticos fracasaron en mejorar el cuadro convulsivo. La paciente fue estudiada con SPECT-99mTc-HMPAO, además de electroencefalograma (EEG), tomografía computada (TCC) y resonancia magnética de cráneo (IRM). Durante el periodo ictal, los estudios de SPECT demostraron un aumento del flujo sanguíneo cerebral en el hemisferio cerebral derecho, y durante el periodo interictal, una disminución del flujo sanguíneo en el mismo hemisferio, particularmente en lóbulo temporal y área rolándica. El EEG mostró descargas epileptógenas continuas caracterizadas por puntas y puntas onda en el hemisferio cerebral. La TCC fue normal y la IRM mostró incremento de la señal en el hemisferio cerebral derecho especialmente en región rolándica y lóbulos temporal y frontal. Se programó para lobectomía temporal y corticectomía frontal derecha. Un estudio histopatológico reveló cambios compatibles con encefalitis viral (síndrome de Rasmussen). La paciente ha continuado sin crisis convulsivasa 10 meses de seguimiento y con programa de rehabilitación intensivo. Regresó a la escuela tres meses después de la cirugía caminando con apoyo de un bastón y su IQ fue normal. Este estudio muestra la utilidad del SPECT en el diagnóstico y manejo de la EPC
