Dual-head Coincidence Gamma Camera Research Articles

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.

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.

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.

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

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)

The clinical application of a dual head gamma camera with coincidence detection in 20 women with suspected ovarian cancer.

To assess the effectiveness of a dual head coincidence gamma camera in identifying ovarian cancer as a less expensive alternative to the traditional 2-[18F] fluoro-2-deoxy-D-glucose (18FDG) system using positron emission tomography. Prospective study. Twenty consecutive women suspected of having ovarian carcinoma. Inclusion was based on abnormal serum CA125 (reference range is 0-35 units/L), ultrasound, computerised tomography or clinical findings. Women underwent assessment before staging laparotomy. Two nuclear medicine physicians, who were blinded to the pre-operative assessment, reported on 18FDG- dual head coincidence gamma camera imaging. The histology and operative staging were compared with the 18FDG- dual head coincidence gamma camera findings. Twelve women had pelvic malignancies (nine primary and three recurrences), seven women had benign pathology and one patient had a borderline malignancy. We were able to image accurately all malignant pelvic masses with dual head coincidence gamma camera, as well as accurately demonstrate disease spread. Two of the benign pelvic masses localised 18FDG. The positive predictive value for detecting malignancy was 86%. Dual head coincidence gamma camera offers accurate and affordable imaging in suspected ovarian masses, with improved specificity over CA125, ultrasound and computerised tomography. These results are similar to those obtained on more expensive dedicated PET systems. We report on a series of patients believed to have primary or recurrent carcinoma and recognise the need to include patients more likely to have benign lesions to assess false positive results. However, we believe that dual head coincidence gamma camera is useful in the pre-operative assessment of women with suspected ovarian cancer.

The clinical application of a dual head gamma camera with coincidence detection in 20 women with suspected ovarian cancer

Objective To assess the effectiveness of a dual head coincidence gamma camera in identifying ovarian cancer as a less expensive alternative to the traditional 2-[ 18F] fluoro-2-deoxy-D-glucose ( 18FDG) system using positron emission tomography. Design Prospective study. Population Twenty consecutive women suspected of having ovarian carcinoma. Inclusion was based on abnormal serum CA125 (reference range is 0–35 units/L), ultrasound, computerised tomography or clinical findings. Methods Women underwent assessment before staging laparotomy. Two nuclear medicine physicians, who were blinded to the pre-operative assessment, reported on 18FDG- dual head coincidence gamma camera imaging. Main outcome measures The histology and operative staging were compared with the 18FDG- dual head coincidence gamma camera findings. Results Twelve women had pelvic malignancies (nine primary and three recurrences), seven women had benign pathology and one patient had a borderline malignancy. We were able to image accurately all malignant pelvic masses with dual head coincidence gamma camera, as well as accurately demonstrate disease spread. Two of the benign pelvic masses localised 18FDG. The positive predictive value for detecting malignancy was 86%. Conclusions Dual head coincidence gamma camera offers accurate and affordable imaging in suspected ovarian masses, with improved specificity over CA125, ultrasound and computerised tomography. These results are similar to those obtained on more expensive dedicated PET systems. We report on a series of patients believed to have primary or recurrent carcinoma and recognise the need to include patients more likely to have benign lesions to assess false positive results. However, we believe that dual head coincidence gamma camera is useful in the pre-operative assessment of women with suspected ovarian cancer.

Usefulness of dual-head coincidence gamma camera with thick nal crystals for nuclear oncology: Comparison with dedicated PET camera and conventional gamma camera with thin NaI crystals

A comparative study of the images obtained with a dual-head coincidence gamma camera with thick NaI crystals (19 mm), a dedicated PET camera with BGO crystals and a conventional gamma camera with thin NaI crystals (9.5 mm) was conducted to clarify the clinical feasibility of a dual-head coincidence gamma camera with thick NaI crystals. FDG images of 27 patients with malignant tumors were obtained by means of a dual-head coincidence gamma camera with thick NaI crystal and a dedicated PET camera with BGO crystals. The images of bone scintigraphy in 10 cancer patients obtained with the dual-head coincidence gamma camera were compared with those taken by a conventional dual-head gamma camera with thin NaI crystals. Patient-basis sensitivity in 27 patients with neoplasms and lesion-basis sensitivity of the dual-head coincidence gamma camera and the dedicated PET camera were 74.1% and 85.2% (n.s.), 66.7% and 72.2% (n.s.), respectively. The tumor to background FDG uptake ratio derived from the coincidence gamma camera was significantly lower than that derived from the dedicated PET camera (mean +/- s.d.; 3.48 +/- 3.77 vs. 8.12 +/- 8.92, p < 0.0001), but the tumor to background FDG uptake ratio obtained with both methods correlated well (r = 0.84, p < 0.001). Similar whole body bone scans were obtained with the dual-head coincidence gamma camera and the conventional dual-head gamma camera in all 10 patients. These results suggest that the dual-head coincidence gamma camera with thick NaI crystals has potentially high clinical applicability for community hospitals.

Coincidence camera FDG imaging for the diagnosis of chronic orthopedic infections: a feasibility study.

Results of dedicated [(18)F]fluoro-2-deoxy-d-glucose (FDG) PET imaging in patients with suspected orthopedic infections are promising. This study evaluates the feasibility of dual-head gamma-camera coincidence (DHC) imaging in this population. Twenty-four patients, referred for the confirmation or exclusion of orthopedic infection, were prospectively studied with consecutive FDG-dedicated PET and FDG DHC imaging. Images were read by two blinded readers experienced with FDG PET and compared with the final diagnosis, obtained by microbiologic proof in 11 patients and clinical follow-up of at least 9 months in 13 patients. Nine patients had osseous infection on final diagnosis. Sensitivity, specificity, and accuracy in this limited series were (Reader 1/Reader 2), respectively, 100/100, 86/86, and 92/92% for FDG-dedicated PET and 89/89, 100/93, and 96/92% for FDG DHC imaging. Despite lower image quality for FDG DHC imaging, results in this limited series were comparable with the results of FDG-dedicated PET. Further studies are needed to confirm the utility of FDG DHC imaging in suspected chronic orthopedic infections in larger patient groups.

Value of Iterative Reconstruction, Attenuation Correction, and Image Fusion in the Interpretation of FDG PET Images with an Integrated Dual-Head Coincidence Camera and X-Ray-based Attenuation Maps

To compare lesion detectability on 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomographic (PET) images obtained with a dual-head coincidence (DHC) gamma camera equipped with an integrated x-ray tube-based transmission system (a) with images reconstructed with filtered back projection (FBP) and those reconstructed with an iterative reconstruction algorithm based on coincidence-ordered subsets expectation maximization (COSEM), (b) with images reconstructed without and with attenuation correction (AC), and (c) with images reconstructed without and with image fusion for anatomic mapping. Thirty-five patients known or suspected to have malignancy underwent initial imaging with a dedicated positron emission tomography (PET) unit after injection of 10 mCi (370 MBq) of FDG. Transmission computed tomographic (CT) scans and FDG emission images were then obtained with the DHC camera. The proportion of lesions detected on the various sets of FDG DHC images was determined by using FDG PET as the standard of reference. Imaging findings were correlated with those from histologic examination and clinical follow-up, in consultation with the respective referring physicians. FDG PET depicted 78 lesions, 29 of which were equal to or less than 1.5 cm in diameter. FDG DHC depicted 52 of the 78 (67%), 59 of 78 (76%), and 61 of the 78 (78%) lesions, respectively, when image reconstruction was performed with FBP without AC, COSEM without AC, and both COSEM and AC. The detection rate of lesions 1.5 cm or smaller was better with COSEM and AC than with FBP (55% vs 34%, respectively). In addition, COSEM and AC allowed more confidence in the interpretation. None of these differences, however, were significant. Fusion of CT scans and FDG DHC images obtained with COSEM and AC allowed localization of lesions to the skeleton in three patients and to the liver versus adjacent bowel in three patients. Image fusion was especially helpful for localizing lesions in the neck in five patients. Anatomic mapping on fusion images was clinically relevant in 11 patients (31%). The COSEM reconstruction algorithm should replace FBP when available. Functional anatomic mapping improved lesion localization in one-third of the patients studied.

Attenuation-Correction Induced Artifact in F-18 FDG PET Imaging Following Total Knee Replacement

Purpose: The clinical use of PET FDG in the work-up of patients with bone and soft tissue malignant tumors is rapidly increasing. The recognition of any source of artifact, therefore, is important to avoid interpretation pitfalls. Procedures: Two patients with complete knee joint replacement by metallic prosthesis in the course of their treatment for malignant bone and soft tissue sarcoma were evaluated by PET F-18 FDG imaging using a dual head coincidence gamma camera. Results: Both studies demonstrated in the attenuation-corrected images intense increase activity at the joint space between the metallic prosthetic surfaces at the level of the knee joint. No uptake, however, was noted in the same location on the non-attenuation-corrected images. Subsequent bone and thallium-201 scans confirmed the absence of tumor recurrence in the first patient. The second patient had multiple follow up F-18 FDG scans over a period of 16 months that show no changes from the baseline study. Conclusion: In the F-18 FDG PET images of patients with total knee metallic prosthesis, an intense activity tends to be seen in the joint space, only in the attenuation-corrected images. Such pattern of uptake is considered artifactual and should always be verified in the non-attenuated images.

15. Sensitivity of FDG CDET (2D Dual-Head Coincidence Gamma Camera) for the Detection of Occult or Doubtful Recurrences of Colorectal Cancer: Histopathological Correlation

Purpose: The aim of this study was to evaluate the efficacy of FDG-CDET for the detection of recurrences of colorectal cancer, in occult disease or in doubtful cases at conventional imaging (CI). In all the evaluated cases, the result of FDG-CDET was compared with post surgical histology both on patient and on site bases.Methods and patients: After fasting for 6h or more, 150-250 MBq of 18F-FDG were injected i.v. and 2D imaging (whole-body scan and at least a tomoscintigram) was started 45 min. later, using a PICKER CDET gamma camera. Among the 214 examinations (ex) performed for detection of recurrences of colorectal cancer between Jul 1997 and Feb 2000, we only considered the 58 cases with negative or questionable CI and a post surgical histologic proof.Results: Patients were referred in three different contexts:1. suspicion of recurrence (SR) due to raising CEA levels with normal CI i.e. occult disease (18 ex: 13 TP, 3 FN, 2 FP on patient basis, 17 TP, 9 FN, 4 FP on site basis)2. SR due to equivocal image(s) at follow-up CI (25 ex: 18 TP, 5 FN, 2 TN on patient basis, 21 TP, 10 FN, 2 TN on site basis)3. SR due to both raising CEA levels and equivocal CI (15 ex: 13 TP, 2 FN on patient basis, 16 TP, 8 FN, 3 TN, 1 FP on site basis).4. The overall sensitivity was 44/54 = 81% on patient basis and 54/81 = 67% on site basis. Specificity could not be evaluated because of the very small number of patients re-operated in case of negative FDG-CDET.5. Conclusion: When conventional imaging could not contribute, i.e. a sensitivity of zero by definition, FDG-CDET accurately diagnosed a recurrence in 81% of the patients and located 67% of all recurrent lesions. These results confirm, with post surgical histology as the only gold standard, that FDG-CDET is a powerful tool for diagnosis of recurrent colorectal cancer in difficult cases. It could be used as the first line examination as soon as a recurrence is suspected, in order to avoid less contributive imaging procedures.

14. FDG CDET (2D Dual-Head Coincidence Gamma Camera) in the Primary Staging of Oesophageal Cancer: Histopathological Correlation

Purpose: The aim of this study was to evaluate the role of FDG-CDET for the detection of primary oesophageal tumour, lymph node involvement and distant extension before surgery.Methods and patients: In patients fasting for 6h or more, 150-250 MBq of 18F-FDG were injected i.v. and 2D imaging (whole-body scan and at least a tomoscintigram) was started 45 min. later, using a PICKER gamma camera. We studied 14 patients (pts). All of them were operated on (mean time between FDG and surgery: 5.4 ± 3.8 days) and staging results were correlated with post surgical histology.Results: The primary lesion took up FDG in all cases but one (FN in a 5 mm lesion). The primary NM staging of these 14 pts was negative with FDG-CDET in 7 cases (4 TN and 3 FN corresponding to an invasion of satellite lymph nodes in 2 cases and to a metastatic infracentimetric subdiaphragmatic lymph node in one case) and positive in 7 cases (7 TP corresponding to 10 foci), revealing in 4 cases a sub-diaphragmatic lymph node extension unknown prior to FDG-CDET. One pt referred for characterisation of an oesophageal lesion (failure of multiple biopsies) had an intense focus of FDG uptake in this area (TP confirmed by surgery). The overall sensitivity was 13/14 = 93% on a per patient basis and 21/25 = 84% on a per lesion basis. Specificity on a per lesion basis was 5/5 = 100%.Conclusion: These first results, obtained in an indication of FDG not frequently evaluated even with dedicated PET systems, seem very promising, the oesophageal neoplastic lesions appearing to take up FDG with a high intensity.

Dual-head coincidence gamma camera FDG PET in patients with colorectal and anal cancer

Dual-head coincidence gamma camera FDG PET in patients with colorectal and anal cancer

Dual-head gamma camera 2-[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography in oncological patients: effects of non-uniform attenuation correction on lesion detection.

The purpose of this study was to evaluate a dual head coincidence gamma camera (DH-PET) equipped with single-photon transmission for 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) imaging in oncological patients. Forty-five patients with known or suspected malignancies, scheduled for a positron emission tomography (PET) scan, were first studied with a dedicated ring PET and subsequently with DH-PET. All patients underwent measured attenuation correction using germanium-68 rod sources for ring PET and caesium-137 sources for DH-PET. Ring PET emission scan was started 64+/-17 min after intravenous administration of 235+/-42 MBq FDG. DH-PET emission followed 160+/-32 min after i.v. FDG. Attenuation-corrected and non-attenuation-corrected images were reconstructed for ring PET and DH-PET. The image sets were evaluated independently by three observers blinded to clinical data and to results of conventional imaging. Attenuation-corrected ring PET as the standard of reference depicted 118 lesions, non-attenuation-corrected ring PET 113 (96%) lesions, and attenuation-corrected DH-PET and non-attenuation-corrected DH-PET, 101 (86%) and 84 (71%) lesions, respectively (P<0.05). The lesion detection rate of attenuation-corrected and non-attenuation-corrected DH-PET was almost similar for lesions >20 mm, whereas attenuation correction increased the detection rate from 60% to 80% for lesions </=20 mm (P<0.01). A patient-based analysis revealed concordant results relative to attenuation-corrected ring PET for non-attenuation-corrected ring PET, attenuation-corrected DH-PET and non-attenuation-corrected DH-PET in 42 (93%), 36 (80%) and 31 (69%) patients, respectively. Differences might have influenced patient management in two (4%), six (13%) and ten (22%) patients, respectively. In conclusion, measured attenuation correction markedly improves the lesion detection capability of DH-PET. With measured attenuation correction the diagnostic performance of DH-PET is closer to that of dedicated ring PET.