Coincidence Gamma Camera Research Articles

Practical assessment of myocardial viability with a positron coincidence gamma camera using 18F-fluorodeoxyglucose in acute myocardial infarction: Comparison with dedicated positron emission tomography and 201Tl single photon emission computed tomography

2-[(18)F] fluoro-2-deoxy-D-glucose ((18)F-FDG) began to be supplied commercially to our hospital, which does not have a cyclotron, in autumn of 2005. The purpose of this study was to compare the utility of a dual-head positron coincidence detection (PCD) gamma camera in the detection of myocardial viability using (18)F-FDG with that of dedicated positron emission tomography (PET) and with that of thallium-201 ((201)Tl) single photon emission computed tomography (SPECT). A total of 15 patients (14 men and 1 woman, mean age: 60+/-7 years, range: 46-73) with a large acute myocardial infarction (AMI) underwent (18)F-FDG PET, (18)F-FDG PCD imaging after oral glucose loading (75 g) and (201)Tl SPECT imaging. We divided the SPECT and PET images into a total of 20 segments, and semiquantitative visual analysis was performed by assessing regional tracer activities on a 4-point scoring system (DS): 0=normal uptake, 1=mildly reduced uptake, 2=severely reduced uptake, and 3=no uptake. We summed the DS in each patient as the total DS (TDS). The TDS of the (18)F-FDG PET image was 14.4+/-7.7. The TDS of the (18)F-FDG PCD image was 18.7+/-7.7. The TDS of the (201)Tl SPECT image was 24.1+/-11.5. The TDS of the (18)F-FDG PET image was significantly smaller than that of the (18)F-FDG PCD image. The TDS of the (18)F-FDG PET image was significantly smaller than that of the (201)Tl SPECT image. The TDS of the (18)F-FDG PCD image was significantly smaller than that of the (201)Tl SPECT image. The findings of the project suggest that (18)F-FDG PCD is a good modality based on its accuracy, convenience, and cost-performance for detecting myocardial viability in hospitals that do not have a PET system.

Negative predictive value of F-18-FDG coincidence PET in patients with Hodgkin's disease and a residual mass after therapy: a retrospective diagnostic test study

Background. The aim of the study was to asses the negative predictive value (NPV) of FDG-PET performed with triple-head coincidence gamma camera after the first-line therapy or salvage therapy in patients with Hodgkin’s disease (HD) compared by a long-term follow-up as a reference standard. Methods. This retrospective diagnostic test study was done at the University Hospital Centre Zagreb between June 2001 and February 2008. The charts of 131 consecutive patients with Hodgkin’s disease were reviewed. Seventy-three consecutive PET-negative patients (median age 28 years; range 12-80 years) with primary or recurrent biopsy confirmed lymphoma after the first-line therapy or salvage therapy were followed-up at least 12 months (median 23 months; range 12-69 months). All already performed 18F-FDG PET scans (using hybrid PET camera with triple head coincidence imaging capability within a few months after the completion of the therapy) were again visually interpreted by two board-certified nuclear medicine physicians who were blinded to any clinical or CT data. The negative predictive value of FDG-PET performed with triple-head coincidence gamma camera (Index test) was compared with a long-term follow-up as a reference standard. Results. Out of 131 patients 73 turned-out to be PET-negative. Of those 73 PET-negative patients, 61 have been scanned after the first-line chemotherapy/radiotherapy, and only 3 of them relapsed in a follow-up (negative predictive value 0.95). Twelve patients with resistant disease have been scanned after the repeated therapy, and 4 of them relapsed in a follow-up period (negative predictive value 0.66). Conclusions. This methodology with a triple-head coincidence gamma camera has a high negative predictive value. A negative PET scan can reassure patients and their doctors that the disease is not active.

Lesion Detectability and Clinical Effectiveness of Dual-head Coincidence Gamma Camera Imaging in Comparison with Dedicated PET Systems in Tumour Patients

The lesion detection capability and clinical effectiveness of dual-head coincidence gamma camera imaging (c-PET) were compared with those of dedicated positron emission tomography (d-PET) in 37 cancer patients who underwent whole-body c-PET and d-PET imaging after administration of 370 - 540 MBq (18)F-fluorodeoxyglucose. Eighty-nine lesions were detected on c-PET whereas 133 lesions were seen with d-PET imaging. The relative sensitivity of c-PET compared with d-PET was 62% and 73% for lesions < 15 and > or = 15 mm, respectively, and the relative concordance rate was 84% when the patients were restaged. Since the lesion detection rate of c-PET imaging was lower than that of d-PET, the detection of small lesions, therefore, requires care. The clinical effectiveness of c-PET, however, was similar to that of d-PET and, therefore, it is concluded that c-PET can be used as an alternative to d-PET, particularly considering the high cost and limited availability of d-PET cameras.

Differential diagnosis of benign and malign pancreatic masses with 18F-fluordeoxyglucose-positron emission tomography recorded with a dual-head coincidence gamma camera

Metabolic imaging using 18F-fluordeoxyglucose and a ring-positron emission tomography camera is an established method in the differential diagnosis of pancreatic masses. Ring-positron emission tomography cameras, however, are expensive and available in only few specialized centres. The aim of this study was to investigate how far 18F-fluordeoxyglucose scan with a conventional dual-head gamma-camera could differentiate between benign and malign pancreatic masses. Forty-one patients (male/female: 25/16; mean age: 64.0 years; range: 41-86 years) with a pancreatic mass detected by ultrasound, computed tomography or MRI were included. In all patients 18F-fluordeoxyglucose scan was performed after overnight fasting and injection of 4 mCi 18F-fluordeoxyglucose using an ADAC Vertex MCD dual head gamma-camera (ADAC; Milpitas, California, USA), equipped with a 5/8-inch NaI-crystal. Images were acquired through a 180 degrees grade rotation in the three dimensional mode. The chosen matrix was 128 x 128 x 16, a Butterworthfilter (ADAC) was used and data were transferred into visible sinograms via Fourier-Rebinning. Coronar, sagittal and transversal slices of 3.9 mm thickness each were acquired. Focal tracer enhancement was suspicious for a malignoma and therefore regarded as positive, diffuse or no tracer uptake was suspicious for a benign process and was regarded as negative for cancer. DEFINITION OF GOLD STANDARDS: A diagnosis of cancer had to be confirmed histologically by specimens obtained by 18G-needle biopsy, surgical resection or at autopsy. A diagnosis of an inflammatory mass was considered proven, if no carcinoma could be found histologically in the surgically resected mass or at autopsy, or if there was no progression of the disease during a follow-up of at least 12 months. In 22 patients carcinoma was diagnosed (pancreatic cancer: n=17; endocrine tumour: n=3; carcinoma of the common bile duct: n=2). 18F-fluordeoxyglucose scan showed a focal tracer enhancement in 19 of these 22 patients (sensitivity: 86.4%). False negative results were acquired in two patients with cancer of the common bile duct and in one patient with poorly controlled insulin-dependent diabetes mellitus. In 19 patients the final diagnosis was an inflammatory pancreatic mass. 18F-fluordeoxyglucose scan showed a diffuse tracer enhancement in 15 of these 19 patients (specificity: 78.9%). False positive results were acquired in three patients whose blood tests showed signs of an acute episode of chronic pancreatitis. Positive and negative predictive values of 18F-fluordeoxyglucose scan were 82.6% and 83.3%, respectively. 18F-fluordeoxyglucose scan with a conventional dual-head gamma-camera is a highly sensitive and specific method in the differential diagnosis of benign and malign pancreatic masses.

Análise comparativa da captação de 18 fluordesoxiglicose por câmara de cintilação e sistema de coincidência e a ecocardiografia de estresse pela dobutamina na detecção de viabilidade miocárdica

To compare Dual-Head coincidence gamma camera (DCD-AC) with dobutamine stress echocardiography (DSE) in viability assessment, using functional recovery as the gold standard. Twenty-one patients were prospectively studied, with coronary artery disease and severe left ventricular dysfunction undergoing DSE and DCD-AC at baseline and DSE three months after revascularization. Of the 290 segments analyzed, 83% were akinetic, 15% hypokinetic and 2% dyskinetic at rest. DSE identified 68% of these segments as non-viable. DCD-AC identified 56% of these segments as normal (dysfunctional segments with preserved metabolism and perfusion), 30% as viable (preserved metabolism and reduced perfusion) and 14% as non-viable (reduced perfusion and metabolism). Of the DSE non-viable segments, DCD-AC identified 80% as normal or viable and 19.9% as non-viable (p<0.001). In hypokinetic segments viability and normal segments were detected in a higher proportion by both methods (p<0.001). DSE sensibility and specificity were 48.3% and 78.1% respectively. DCD-AC sensibility and specificity was 92.2% and 20.0%. DCD-AC identifies a higher incidence of function improvement in normal segments than in viable and non-viable. DCD-AC classified as normal or viable most of the non-viable DSE segments. In assessment of functional recovery segments after three months, DCD-AC showed a high sensibility but low specificity.

Quantitative measurement of cerebral metabolic rate of glucose by means of dual-head coincidence gamma camera and 2-deoxy-2- [18F] fluoro-D-glucose

Quantitative measurement of cerebral metabolic rate of glucose by means of dual-head coincidence gamma camera and 2-deoxy-2- [¹⁸F] fluoro-D-glucose

In Vivo Follow-up of Rat Tumor Models with 2-Deoxy-2-[F-18]fluoro-d-glucose/Dual-Head Coincidence Gamma Camera Imaging

Before studying the impact of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) imaging with a dual-head coincidence gamma camera (DHC) for the follow-up of animal tumor models, we wanted to optimize this technique. Three different animal tumor models (osteosarcoma, melanoma, and breast cancer) were studied after FDG injection. Dynamic and dual time point FDG/DHC imaging were studied from one hour to five hours postinjection. In vitro tumor cell FDG uptake was assessed in eight different tumor cell lines. In one model (osteosarcoma), tumor growth, lung metastasis emergence, and survival were assessed by classical clinical follow-up and compared to FDG imaging in a control group (n = 6) and in a group treated by endostatin liposome complexes (n = 6). Images obtained five hours after injection were more reliable for tumor growth follow-up than standard images (one hour). In vitro tumor cell FDG uptake confirmed in vivo imaging studies. In eight different tumor cell lines the FDG uptake was higher after five hours incubation than after one hour (p < 0.002). With FDG follow-up, we found that FDG uptake was strongly correlated with survival and that lung metastasis larger than 5 mm could be detected. Using the optimization proposed above, DHC/FDG functional imaging seems to be a powerful tool to study rat tumor models and to help develop novel cancer therapies.

Direct comparison of 18F‐fluorodeoxyglucose coincidence gamma camera tomography with gallium scanning for the staging of lymphoma

The present study compared the performance of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) using a coincidence dual-head gamma camera (FDG Co-PET) with 67gallium scinti graphy (GS) in pretreatment staging of lymphoma. A total of 46 patients underwent FDG Co-PET, computed tomography (CT) scanning and GS for pretreatment staging of lymphoma (40 newly diagnosed and recurrence) between November 1997 and December 1999. Histological subgroups comprised low grade (8 patients), intermediate grade (25) high-grade (3) non-Hodgkin's lymphoma and Hodgkin's disease (10). Based on clinical assessment, CT scan findings and biopsy, 100 nodal sites and 15 extra-nodal sites were deemed positive. FDG Co-PET was superior to GS in nodal site positivity rate (97%vs 79%, P < 0.0001). Compared with GS, FDG Co-PET detected 39 more abnormal sites in 22 patients (48%), of which 28 sites were validated by biopsy, CT and/or progress FDG Co-PET scanning. There was only one proven false negative FDG site in the spleen. CT + FDG Co-PET led to upstaging in 2 patients (4%), compared to CT + GS. FDG Co-PET shows potential for providing an accurate means for pretreatment staging of lymphoma and can detect extra sites of disease activity compared to GS.

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.

Detection of recurrent colorectal carcinoma by 18F-FDG: comparison of the clinical performances of FDG PET and FDG CDET

To assess the clinical performance of fluorodeoxyglucose positron emission tomography (FDG PET) using either a coincidence (CDET) gamma camera or PET equipment with Nal crystals for the detection of recurrences of colorectal cancer. From July 1997 to December 1999, 290 examinations were performed in 244 patients using a CDET gamma camera (2-dimensional system with 19 mm thick crystals). Additionally, from January 2000 to July 2002, 354 examinations were performed in 303 patients using PET (3-dimensional system with Nal crystals). Four hundred and seventy-three of the 644 examinations performed were evaluable on the basis of histological data (202 examinations) or more than 6 months of follow-up (273 examinations). The performances of the two systems were equivalent on a patient basis (sensitivity, specificity and accuracy of dedicated PET was 92%, 84% and 90%, respectively; and sensitivity, specificity and accuracy of CDET was 90%, 94% and 91%, respectively). On a site basis, a highly significant reduction in sensitivity was observed for lesions < or = 10 mm vs. > 10 mm with both PET and the CDET gamma camera, but no difference was observed between PET and CDET according to the size of the lesions. For detection of recurrent colorectal carcinoma, a 2-D coincidence gamma camera with 19 mm thick crystals and optimized acquisition and reconstruction parameters provides similar results in terms of accuracy, both per patient and per site, to those of an Nal PET camera.

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.

Comparative impact of standard approach, FDG PET and FDG dual-head coincidence gamma camera imaging in preoperative staging of patients with non-small-cell lung cancer

We prospectively compared the impact of the standard approach, of fluorodeoxyglucose positron emission tomography (FDG PET) and of FDG dual-head coincidence gamma camera imaging (DHC) in preoperative staging of patients with non-small-cell lung cancer (NSCLC). In addition to traditional staging, 42 patients were studied with a PET system and a DHC system. The number of lesions detected on DHC and on PET were compared independently of the proof of a tumoural invasion. Then, for the sub-group of lesions with the proof of a tumoural invasion, the sensitivity of the different imaging modalities was compared. Finally, stagings were compared with final staging established by histopathological findings (n=28), additional imaging modalities (n=4), clinical and traditional imaging follow-up over at least 4 months. DHC detected 105 of the 145 lesions considered as pathological on PET (73%, P=0.01), with a concurrence of 89% (NS) in lesions larger than 1.5 cm, and only 17% (P=0.03) in those smaller or equal to 1 cm. Traditional staging detected 87 of the 114 verified tumoural lesions (76%), PET 110/114 (96%, P=0.01 vs traditional staging), DHC 88/114 (77%, NS vs traditional staging, P=0.01 vs PET). PET correctly predicted the N stage in 39/42 (93%) patients, DHC in 38/42 (90%), and computed tomography in 32/42 (76%). PET correctly predicted the M stage in 42/42 (100%) patients, DHC in 41/42 (98%), and traditional staging in 38/42 (90%). Identical NM staging was obtained with DHC and PET in 38/42 (90%) patients. Compared to traditional NM staging, PET correctly up-staged 9/42 (21%) patients and down-staged 3/42 (7%), with one additional false N up-staging. DHC correctly up-staged 7/42 (17%) patients and down-staged 3/42 (7%), with one additional false N down-staging. PET correctly reclassified 4/42 (9.5%) patients from resectable to unresectable and incorrectly reclassified one. DHC correctly reclassified 3/42 (7%) patients without false therapeutic reclassification. Although DHC detected fewer lesions than PET, DHC is a possible alternative to PET since the impact on staging was high as compared with traditional staging and was very similar to that of PET.

The suitability of gamma camera coincidence systems for nitrogen 13–labeled ammonia myocardial perfusion imaging: a quantitative comparison with full-ring PET

Background The aim of this study was to examine the quality of nitrogen 13–labeled ammonia (NH 3) perfusion data from coincidence-capable gamma camera positron emission tomography (GC-PET) systems compared with that from full-ring positron emission tomography (FR-PET). Methods and results The performance parameters of the GC-PET system were examined and found adequate for imaging at the activity levels used clinically. We studied 15 patients who underwent stress and rest N-13–labeled NH 3 perfusion imaging on FR-PET and GC-PET systems. Quantitative analysis of perfusion values showed that GC-PET uptake was significantly lower than FR-PET uptake in 67.6% of segments. Bland-Altman analysis showed that the mean difference between FR-PET and GC-PET values was from 5.3% to 5.9%. Stress FR-PET identified 49 segments as having impaired perfusion, 46 (93.9%) of which were also identified by GC-PET. Fifty-six additional segments were identified as abnormal by GC-PET. These findings indicated a general overestimation of defect size on GC-PET. Analysis of the degree of perfusion reduction also found that GC-PET tended to overestimate defect contrast. These findings are similar to those previously found by workers examining fluorine 18–fluorodeoxyglucose uptake by both techniques. Conclusions Good concordance was shown between GC-PET and FR-PET systems for N-13–labeled NH 3 perfusion imaging, although further work is required to optimize the technique.

Differentiation between malign and inflammatory pancreatic masses by fluorine-18 fluorodeoxyglucose (18F-FDG) scan using a dual-head coincidence gamma-camera

Differentiation between malign and inflammatory pancreatic masses by fluorine-18 fluorodeoxyglucose (18F-FDG) scan using a dual-head coincidence gamma-camera

Fluorodeoxyglucose imaging using a coincidence gamma camera to detect head and neck squamous cell carcinoma and response to chemotherapy.

This prospective study was performed to evaluate the ability of a dual-head gamma camera with fluorine-18 fluorodeoxyglucose coincidence detection emission tomography (FDG-CDET) to detect primary tumor and cervical lymph nodes in head and neck squamous cell carcinoma (HNSCC), and to show the response of the carcinoma to chemotherapy. The findings were compared with those of physical examination, computed tomography (CT), and histopathology, before treatment in 61 patients, and after induction chemotherapy in 34 of them. Before treatment, the primary was detected in 93%, 79%, and 95% of cases on panendoscopy, CT, and FDG-CDET, respectively. After chemotherapy, 34 patients were evaluable for response of the primary tumor. Surgical resection was performed in 23 of them: agreement with histopathologic results for response to treatment was 74%, 69%, and 78% for panendoscopy, CT, and FDG-CDET, respectively. No surgical resection was performed in 11 of the 34 patients, but biopsies were performed before radiotherapy, and their rates of agreement with histopathologic results for response to treatment were 75%, 75%, and 67% on panendoscopy, CT, and FDG-CDET, respectively. For cervical lymph nodes, 245 sites were resected in 41 patients, and FDG-CDET appeared competitive with CT in detecting metastatic neck disease, especially after neoadjuvant chemotherapy; the accuracy was 93%. These results demonstrated the ability of FDG-CDET to detect primary tumors and cervical lymph nodes in HNSCC and to show its response to chemotherapy, as compared to the ability of CT and panendoscopy. It may be a complementary tool to evaluate residual disease after induction chemotherapy, although higher sensitivity would be required for FDG-CDET to be considered as a staging modality.

PET imaging using a triple-head gamma camera.

Interest in clinical fluorodeoxyglucose (FDG) imaging with multiple-head gamma cameras is growing. To improve sensitivity, triple-head coincidence imaging has been proposed. We report our initial experiences with a triple-head coincidence gamma camera with 19 mm sodium iodide crystal thickness. Several positron emission tomography-image quality parameters were evaluated using a Carlson and line source phantom. The system sensitivity with two-dimensional axial shields was 830 cps kBq-1 ml-1 and maximum noise equivalent count rate 1900 cps for an 18F-activity of 50 MBq. The imaging resolution was in central axial 7.0 mm and in central transaxial 7.6 mm, respectively. The average scatter fraction in scattered media was 29%. Clinical brain, heart and whole body images studies with [18F]FDG were acquired and they show good correlation with the phantom image quality. As a conclusion, triple-head coincidence gamma camera provides relatively high-count rate imaging with good contrast and resolution.

Detection of lung cancer with positron coincidence gamma camera using fluorodeoxyglucose in comparison with dedicated PET

Objective: Dual-head gamma cameras with sodium iodide (NaI) detectors operated in coincidence mode provide a new approach for imaging with positron-labeled tracers. The purpose of this study was to evaluate the feasibility of FDG imaging with positron coincidence detection gamma camera (PCD) in detecting lung tumor in comparison with FDG imaging with the dedicated positron emission tomography (PET). Methods and material: Twenty-six lesions of 13 patients with suspected lung cancer were studied with both FDG PET and FDG PCD on the same day. Pulmonary lesions were analyzed visually and semi-quantitatively using the ratio of target-to-background counts (T/B ratio). Results and conclusions: FDG PCD and FDG PET could detect visually 21 lesions (80.8%) and 23 lesions (88.0%), respectively. The mean T/B ratio and standard deviation (S.D.) of FDG PCD was 4.6±3.9, significantly lower than that of FDG PET (11.4±6.6, P<0.001). When pulmonary lesions were no more than 2.0 cm in diameter, the sensitivity of FDG PCD was 37.5%, significantly inferior to that of FDG PET (62.5%, P<0.001). There was no statistically significant difference of the sensitivity between the FDG PCD and FDG PET in lesions of more than 2.0 cm in diameter. FDG PCD with uniform attenuation correction was clinically available in detecting lung cancer. However, the sensitivity for small lesions less than 2.0 cm was limited. The application of measured attenuation correction and scatter correction may to be needed to improve the detectability of FDG PCD, especially for detecting small lung cancer.

Oncological diagnosis using positron coincidence gamma camera with fluorodeoxyglucose in comparison with dedicated PET

The purpose of this study was to compare the utility of a dual-head positron coincidence detection gamma camera (PCD) with that of dedicated positron emission tomography (PET) in the imaging of various malignancies using (18)F-fluorodeoxyglucose (FDG). 25 patients with known or suspected malignancies at various sites underwent imaging with both methods, and diagnostic performance on a lesion basis was compared. Tumour lesions were analyzed visually and semi-quantitatively using the ratio of tumour-to-background counts (T/B ratio). FDG PCD and FDG PET visually detected 34 (72.3%) lesions and 37 (78.7%) lesions, respectively. The mean T/B ratio and standard deviation (SD) of FDG PCD was 3.5+/-3.3, significantly lower than that of FDG PET (8.4+/-7.1, p<0.001). When tumour lesions were less than 2.0 cm in diameter, the sensitivity of FDG PCD was 37.5%, significantly inferior to that of FDG PET (50.0%, p<0.01). Sensitivity between FDG PCD and FDG PET in lesions of more than 2.0 cm diameter showed no statistically significant difference. This study indicates that FDG imaging with a dual-head coincidence detection gamma camera can provide suitable diagnostic performance for lesions greater than 2.0 cm diameter, but performed significantly worse than dedicated PET for lesions smaller than this.

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)