Gamma Camera Coincidence Imaging Research Articles

Dual-Head gamma camera coincidence imaging in pancreatic cancer

To assess the usefulness of dualhead camera imaging with 2-[fluorine-18]fluoro-2-deoxy- D-glucose (FDG) in the identification of malignant pancreatic lesions. Fifteen (15) patients with pancreatic masses (7 females and 8 males, mean age 52 ± 10 years) have been studied prospectively. After a 12-hour fasting patients received 120 MBq of FDG and were imaged in a dual-head camera equipped with coincidence detection. The final diagnosis was obtained by histology (biopsy or surgery in 13 patients) or follow-up (in 2 patients). Nine patients showed FDG uptake, all had pancreatic cancer proven on histological examination. Six patients had no tracer uptake: two had chronic pancreatitis, 1 had insulinoma, 1 had gastrinoma and two had pancreatic adenocarcinoma. Overall sensitivity was 69 %, specificity was 100 % and accuracy was 73%. Dual-head camera FDG images seem potentially useful in the characterization of the nature of pancreatic lesions. However, a negative study does not rule out malignancy in this patient population. Evaluar la utilidad de la realización de imagen con, 2-flúor-2 desoxi-D-glucosa-18F (FDG) em gammacámara de doble cabezal en la identificación de lesiones pancreáticas malignas. Hemos estudiado en carácter prospectivo 15 pacientes con masas pancreáticas (7 mujeres y 8 hombres, edad promedio 52 ± 10 años). Después de un ayuno de 12 horas los pacientes recibieron 120 MBq de FDG y equipada con detección por coincidencia. El diagnóstico final se obtuvo por histología (biopsia o cirugía en 13 pacientes) o por seguimiento (en 2 pacientes). Nueve pacientes mostraron captación de FDG, todos tuvieron cáncer pancreático probado con base en examen histológico. Seis pacientes no tuvieron captación del radiofármaco: dos pancreatitis crónicas, 1 insulinoma, 1 gastrinoma y dos adenocarcinomas pancreáticos. La sensibilidad global fue del 69 %, la especificidad fue 100 % y la exactitud fue del 73%. Las imágenes realizadas com FDG en cámara de doble cabezal equipada com detección por coincidencia parecen potencialmente útiles en la caracterización de lesiones pancreáticas, mientras que un estudio negativo no descarta totalmente malignidad.

Dual-Head gamma camera coincidence imaging in pancreatic cancer

To assess the usefulness of dual-head camera imaging with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in the identification of malignant pancreatic lesions. Fifteen (15) patients with pancreatic masses (7 females and 8 males, mean age 52 10 years) have been studied prospectively. After a 12-hour fasting patients received 120 MBq of FDG and were imaged in a dual-head camera equipped with coincidence detection. The final diagnosis was obtained by histology (biopsy or surgery in 13 patients) or follow-up (in 2 patients). Nine patients showed FDG uptake, all had pancreatic cancer proven on histological examination. Six patients had no tracer uptake: two had chronic pancreatitis, 1 had insulinoma, 1 had gastrinoma and two had pancreatic adenocarcinoma. Overall sensitivity was 69%, specificity was 100% and accuracy was 73%. Dual-head camera FDG images seem potentially useful in the characterization of the nature of pancreatic lesions. However, a negative study does not rule out malignancy in this patient population.

Gamma camera coincidence imaging in oncology

Imaging positron-emitters, such as 18F-fluorodeoxyglucose (FDG), using a gamma camera in coincidence mode is an exciting development in recent years. The proven clinical utility of FDG positron emission tomography (PET) in oncology and high cost of a PET scanner led to the development of this cheaper alternative. Gamma camera coincidence imaging (GCI) is capable of both positron and single-photon imaging. There are substantial differences in system design and performances between GCI and PET. GCI yields a spatial resolution comparable to that of PET, but the system sensitivity and lesion-detection capability, particularly for smaller lesions, are inferior. Despite these limitations, the clinical experiences with GCI in various oncological patients are so far encouraging. Recent advances in detectors, attenuation correction, and iterative reconstruction algorithms look promising to develop coincidence imaging as an appealing alternative to PET for clinical positron imaging.

The Role of Fluorine-18-fluorodeoxyglucose (FDG) Dual-head Gamma Camera Coincidence Imaging in Patients with Colorectal Cancer and Unexplained Rising Levels of Carcinoembryonic Antigen (CEA)

The Role of Fluorine-18-fluorodeoxyglucose (FDG) Dual-head Gamma Camera Coincidence Imaging in Patients with Colorectal Cancer and Unexplained Rising Levels of Carcinoembryonic Antigen (CEA)

Multiple point sources collimated with transaxial septa for high energy gamma camera transmission scanning

The axial imaging properties of the transmission scanning system for attenuation correction of gamma camera coincidence imaging are evaluated. This system uses multiple Cs-137 point sources collimated by transaxial septa already in place for emission imaging. Both the spacing and the degree of collimation of the sources can be controlled. Axial image quality was evaluated with three levels of collimation (4 mm, 7 mm, and 10 mm slot, all 6 cm deep) and two source spacing distances (1.3 cm and 2.6 cm). A multiple disk phantom with adjustable spacing was imaged, as well as a thorax phantom. The 4 mm collimation and 1.3 cm source spacing provided well-resolved images of the disks with 2.9 cm center-to-center spacing. The best collimation/spacing combinations come with substantial overlap of flux from difference sources in the detector. Axial resolution can be adequately controlled with extra lead collimation of the sources.

Clinical Experience with Dual Head Gamma Camera Coincidence Imaging

The authors report their experience with F-18 FDG coincidence imaging (CI) on a Dual Head Gamma Camera system employed for more than 2 years starting on August 23, 1996 within a community hospital. The latest version of this system included attenuation correction since May 1998. The problems with such systems and approaches in correcting these problems are described. This new technology promises to make F-18 FDG imaging available to community hospitals that may have a limited patient population and cannot afford the costs of a dedicated PET system. We feel that CI is cost effective and provides useful clinical information. We stress that this is our own opinion supported by the satisfaction of referring clinicians in answering clinical questions regarding their patients’ clinical problems. CI with these systems provide imaging of F-18 FDG using three to six mCi. These systems are not suitable for short half-life positron emitters such as Carbon-11 and Oxygen-15.

Attenuation effects in gamma-camera coincidence imaging

Images produced by gamma camera coincidence (GCC) techniques have a much lower count-density than those produced by dedicated PET scanners. The authors examine the effects of attenuation and attenuation correction on GCC images using gamma-camera emission data and PET emission and transmission data from phantom and human studies. The effects studied include contrast, noise, and general image quality. Results show that lung lesion contrast is improved but the signal-to-noise ratio is slightly degraded by the application of attenuation correction. Additionally, the corrected images do not contain the distortions of the uncorrected images and they more accurately show the activity distribution of the imaged object. The noise studies suggest that statistically appropriate transmission data for implementing an attenuation correction can be acquired in a small fraction of the time used for an emission scan.