Compared vulnerabilities to small cardiac motions between different cameras used for myocardial perfusion imaging.

This phantom-based study was aimed to determine whether cardiac CZT-cameras, which provide an enhanced spatial resolution and image contrast compared to Anger cameras, are similarly affected by small cardiac motions. Translations of a left ventricular (LV) insert at half-SPECT acquisitions through six possible orthogonal directions and with 5- or 10-mm amplitude were simulated on the Discovery NM-530c and DSPECT CZT-cameras and on an Anger Symbia T2 camera equipped with an astigmatic (IQ.SPECT) or conventional parallel-hole collimator (Conv.SPECT). SPECT images were initially reconstructed as currently recommended for clinical routine. The heterogeneity in recorded activity from the 17 LV segments gradually increased between baseline and motions simulated at 5- and 10-mm amplitudes with all cameras, although being higher for Anger- than CZT-cameras at each step and resulting in a higher mean number of artifactual abnormal segments (at 10-mm amplitude, Conv.SPECT: 3.7; IQ.SPECT: 1.8, Discovery: 0.7, DSPECT: 0). However, this vulnerability to motion was markedly (1) decreased for Conv.SPECT reconstructed without the recommended Resolution Recovery algorithm and (2) increased for DSPECT reconstructed without the recommended cardiac model. CZT-cameras and especially the DSPECT appear less vulnerable to small cardiac motions than Anger-cameras although these differences are strongly dependent on reconstruction parameters.

Mapping of failures after radiochemotherapy in patients with non-metastatic esophageal cancer: A posteriori analysis of the dose distribution in the sites of loco-regional relapse.

BACKGROUND AND PURPOSE: We aimed to evaluate the patterns of loco-regional failure (LRF) after exclusive chemoradiotherapy (eCRT) for esophageal cancer with respect to planned dose and/or the incidental (unplanned) dose outside target volumes. MATERIALS AND METHODS: Co-image registration of CT or (18)F-FDG PET-CT at the time of failure (tf) and at the time of CRT (t0) was performed in 34 patients with LRF. Dosimetric parameters with regard to local failure (LF), nodal failure (NF) and involved nodal stations (NS) were derived. RESULTS: Twenty-two patients (64.7%) had LF, the majority of which (95.5%) were located at the epicenter of the GTV of the primary tumor. The mean doses recalculated to the NS at tf were more likely to be lower than the planned dose delivered to the PTV at t0: Dmean=33.9 ± 20.8 Gy vs 52.2 ± 8.5 Gy (p=0.0009), D95%=27.5 ± 21 Gy vs 46.1 ± 4.8 Gy (p=0.004). Among the 12 patients with NF outside the elective nodal irradiation (ENI) volume, Dmean of NS outside the ENI was significantly lower (19.4 ± 21.4 Gy) than the Dmean of NS with failure within the ENI (45.1 ± 6.1 Gy, p=0.01). CONCLUSION: Loco-regional failure after exclusive chemoradiotherapy for esophageal cancer may be due to an inadequately low dose.

Early 18F-FDG PET for prediction of prognosis in patients with diffuse large B-cell lymphoma: SUV-based assessment versus visual analysis.

UNLABELLED: The purpose of this study was to assess the prognostic value of early (18)F-FDG PET using standardized uptake value (SUV) compared with visual analysis in patients with diffuse large B-cell lymphoma (DLBCL). METHODS: Ninety-two patients with newly diagnosed DLBCL underwent (18)F-FDG PET prospectively before and after 2 cycles of chemotherapy (at midtherapy). Maximum SUV (SUVmax) and mean SUV (SUVmean) normalized to body weight and body surface area, as well as tumor-to-normal ratios, were computed on the most intense uptake areas. The SUVs, tumor-to-normal ratios, and their changes over time were compared with visual analysis for predicting event-free survival (EFS) and overall survival, using receiver-operating-characteristic (ROC) analysis. Survival curves were estimated with Kaplan-Meier analysis and compared using the log-rank test. RESULTS: With visual analysis, the accuracy of early PET to predict EFS was 65.2%. The 2-y estimate for EFS was 51% (95% confidence interval [CI], 34%-68%) in the PET-positive group compared with 79% (95% CI, 68%-90%) in the PET-negative group (P = 0.009). An optimal cutoff value of 65.7% SUVmax reduction from baseline to midtherapy obtained from ROC analysis yielded an accuracy of 76.1% to predict EFS. The 2-y estimate for EFS was 21% (95% CI, 0%-42%) in patients with SUVmax reduction 65.7% (P < 0.0001). Fourteen patients considered as positive on visual analysis could have been reclassified as good responders. CONCLUSION: SUV-based assessment of therapeutic response during first-line chemotherapy improves the prognostic value of early (18)F-FDG PET compared with visual analysis in DLBCL.

[F-18]-Fluoro-2-deoxy-D: -glucose positron emission tomography as a tool for early detection of immunotherapy response in a murine B cell lymphoma model.

[F-18]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is a non-invasive imaging technique which has recently been validated for the assessment of therapy response in patients with aggressive non-Hodgkin's lymphoma. Our objective was to determine its value for the evaluation of immunotherapy efficacy in immunocompetent Balb/c mice injected with the A20 syngeneic B lymphoma cell line. The high level of in vitro FDG uptake by A20 cells validated the model for further imaging studies. When injected intravenously, the tumour developed as nodular lesions mostly in liver and spleen, thus mimicking the natural course of an aggressive human lymphoma. FDG-PET provided three-dimensional images of tumour extension including non-palpable lesions, in good correlation with ex vivo macroscopic examination. When mice were pre-immunized with an A20 cell lysate in adjuvant before tumour challenge, their significantly longer survival, compared to control mice, were associated with a lower incidence of lymphoma visualized by PET at different time points. Estimation of tumour growth and metabolism using the calculated tumour volumes and maximum standardized uptake values, respectively, also demonstrated delayed lymphoma development and lower activity in the vaccinated mice. Thus, FDG-PET is a sensitive tool relevant for early detection and follow-up of internal tumours, allowing discrimination between treated and non-treated small animal cohorts without invasive intervention.

[Basics of PET and PET/CT imaging: instrumentation and radiopharmaceuticals for clinical diagnosis]. / Bases de la TEP et de la TEP/TDM: machines et médicaments radiopharmaceutiques pour le diagnostic clinique.

Positron emission tomography (PET), like scintigraphy, is a type of functional and molecular imaging. Image resolution is better than with scintigraphy, and tomographic slices are obtained, as with CT and MRI. Modern PET machines are coupled with CT (PET/CT) and yield fused images that combine metabolic and anatomic approaches. Fludeoxyglucose (FDG), a radiolabeled glucose analog, is the most widely used radiopharmaceutical for clinical PET, but several other molecules are proposed for routine use. Clinical trials will determine which are of clinical interest. FDG imaging necessarily involves PET but clinical PET is not only FDG imaging.

Impact of CT and 18F-deoxyglucose positron emission tomography image fusion for conformal radiotherapy in esophageal carcinoma.

PURPOSE: To study the impact of fused (18)F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on conformal radiotherapy planning for esophageal carcinoma patients. METHODS AND MATERIALS: Thirty-four esophageal carcinoma patients were referred for concomitant radiotherapy and chemotherapy with radical intent. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same treatment position. PET images were coregistered using five fiducial markers. Target delineation was initially performed on CT images, and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume. RESULTS: (18)F-fluorodeoxy-D-glucose-PET identified previously undetected distant metastatic disease in 2 patients, making them ineligible for curative conformal radiotherapy. The gross tumor volume (GTV) was decreased by CT and FDG image fusion in 12 patients (35%) and increased in 7 patients (21%). The GTV reduction was > or =25% in 4 patients owing to a reduction in the length of the esophageal tumor. The GTV increase was > or =25% with FDG-PET in 2 patients owing to the detection of occult mediastinal lymph node involvement in 1 patient and an increased length of the esophageal tumor in 1 patient. Modifications of the GTV affected the planning treatment volume in 18 patients. Modifications of the delineation of the GTV and displacement of the isocenter of the planning treatment volume by FDG-PET also affected the percentage of total lung volume receiving >20 Gy in 25 patients (74%), with a dose reduction in 12 patients and dose increase in 13. CONCLUSION: In our study, CT and FDG-PET image fusion appeared to have an impact on treatment planning and management of esophageal carcinoma. The affect on treatment outcome remains to be demonstrated.

Impact of computed tomography and 18F-deoxyglucose coincidence detection emission tomography image fusion for optimization of conformal radiotherapy in non-small-cell lung cancer.

PURPOSE: To report a retrospective study concerning the impact of fused 18F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and CT images on three-dimensional conformal radiotherapy planning for patients with non-small-cell lung cancer. METHODS AND MATERIALS: A total of 101 patients consecutively treated for Stage I-III non-small-cell lung cancer were studied. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same treatment position. Images were coregistered using five fiducial markers. Target volume delineation was initially performed on the CT images, and the corresponding FDG-PET data were subsequently used as an overlay to the CT data to define the target volume. RESULTS: 18F-fluoro-deoxy-D-glucose-PET identified previously undetected distant metastatic disease in 8 patients, making them ineligible for curative conformal radiotherapy (1 patient presented with some positive uptake corresponding to concomitant pulmonary tuberculosis). Another patient was ineligible for curative treatment because the fused PET-CT images demonstrated excessively extensive intrathoracic disease. The gross tumor volume (GTV) was decreased by CT-PET image fusion in 21 patients (23%) and was increased in 24 patients (26%). The GTV reduction was > or = 25% in 7 patients because CT-PET image fusion reduced the pulmonary GTV in 6 patients (3 patients with atelectasis) and the mediastinal nodal GTV in 1 patient. The GTV increase was > or = 25% in 14 patients owing to an increase in the pulmonary GTV in 11 patients (4 patients with atelectasis) and detection of occult mediastinal lymph node involvement in 3 patients. Of 81 patients receiving a total dose of > or = 60 Gy at the International Commission on Radiation Units and Measurements point, after CT-PET image fusion, the percentage of total lung volume receiving >20 Gy increased in 15 cases and decreased in 22. The percentage of total heart volume receiving >36 Gy increased in 8 patients and decreased in 14. The spinal cord volume receiving at least 45 Gy (2 patients) decreased. Multivariate analysis showed that tumor with atelectasis was the single independent factor that resulted in a significant effect on the modification of the size of the GTV by FDG-PET: tumor with atelectasis (with vs. without atelectasis, p = 0.0001). CONCLUSION: The results of our study have confirmed that integrated hybrid PET/CT in the treatment position and coregistered images have an impact on treatment planning and management of non-small-cell lung cancer. However, FDG images using dedicated PET scanners and respiration-gated acquisition protocols could improve the PET-CT image coregistration. Furthermore, the impact on treatment outcome remains to be demonstrated.

In vivo follow-up of rat tumor models with 2-deoxy-2-[F-18]fluoro-D-glucose/dual-head coincidence gamma camera imaging.

UNLABELLED: 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. METHODS: 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). RESULTS: 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. CONCLUSION: 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.

Laparoscopic resection of occult metastasis using the combination of FDG-positron emission tomography/computed tomography image fusion with intraoperative probe guidance in a woman with recurrent ovarian cancer.

BACKGROUND: Positron emission tomography and computed tomography (PET/CT) have a potential role in detecting and locating recurrent ovarian cancer. Precise tumor location during surgical treatment is often difficult, owing to limited tumor size and post-surgical anatomic modifications. The surgical gamma probe, which has become increasing popular in recent years with the development of sentinel node mapping, may improve tumor detection and facilitate resection of occult metastases. CASE REPORT: We describe the first case of laparoscopic resection of occult metastasis using the combination of FDG-PET/CT image fusion with intraoperative FDG-sensitive probing in a patient with recurrent ovarian cancer. CONCLUSION: FDG-sensitive probe combined with preoperative PET/CT image fusion can help to detect occult metastasis and guide laparoscopic excision.

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

OBJECTIVES: 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. METHODS: 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). RESULTS: 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. CONCLUSION: 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.

Activity and diffusion of tigecycline (GAR-936) in experimental enterococcal endocarditis.

The activity of tigecycline (GAR-936), a novel glycylcycline, was investigated in vitro and in experimental endocarditis due to the susceptible Enterococcus faecalis JH2-2 strain, its VanA type transconjugant BM4316, and a clinical VanA type strain, E. faecium HB217 resistant to tetracycline. MICs of GAR-936 were 0.06 micro g/ml for the three strains. In vitro pharmacodynamic studies demonstrated a bacteriostatic effect of GAR-936 that was not enhanced by increasing concentrations to more than 1 micro g/ml and a postantibiotic effect ranging from 1 to 4.5 h for concentrations of 1- to 20-fold the MIC. Intravenous injection of [(14)C]GAR-936 to five rabbits with enterococcal endocarditis sacrificed 30 min, 4 h, or 12 h after the end of the infusion evidenced a lower clearance of GAR-936 from aortic vegetations than from serum and a homogeneous diffusion of GAR-936 into the vegetations. In rabbits with endocarditis, GAR-936 (14 mg/kg of body weight twice a day [b.i.d.]) given intravenously for 5 days was bacteriostatic against both strains of E. faecalis. Against E. faecium HB217, bacterial counts in vegetations significantly decreased during therapy (P < 0.01), and the effect was similar with GAR-936 at 14 mg/kg b.i.d., 14 mg/kg once a day (o.d.), and 7 mg/kg o.d., which provided concentrations in serum constantly above the MIC. Mean serum elimination half-life ranged from 3.3 to 3.6 h. No GAR-936-resistant mutants were selected in vivo with any regimen. We concluded that the combination of prolonged half-life, significant postantibiotic effect, and good and homogeneous diffusion into the vegetations may account for the in vivo activity of GAR-936 against enterococci susceptible or resistant to glycopeptides and tetracyclines, even when using a o.d. regimen in rabbits.