18F-FDG PET/CT in pancreatic adenocarcinoma: A role at initial imaging staging?

Pancreatic ductal adenocarcinoma represents 90% of all pancreatic tumors. The only hope for prolonged survival in patients with this condition still remains surgery with complete R0 resection. Initial imaging has a pivotal role to identify patients who are eligible to curative surgery and those who may benefit of neoadjuvant chemotherapy. This review provides an analysis of the recent literature on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in pancreatic adenocarcinoma. Performances of FDG PET in the detection of lymph node involvement and metastatic spread at initial staging and those in the assessment of response to treatment are described.

Relationship between lymphoscintigraphy and clinical findings in lower limb lymphedema (LO): toward a comprehensive staging.

Although radionuclide lymphoscintigraphy (RNL) is widely used diagnostically for patients with lymphedema (LE), it has not been utilized for LE staging, which is still based upon clinical findings. The aim of this work is to establish whether the results of both conventional RNL and fusion imaging obtained from hybrid detectors may be used for a comprehensive clinicoimaging staging in LE. Radiolabeled nanocolloids (0.2 ml) were subcutaneously injected in 4,328 patients (23-78 years) with clinical lower limb LE and without venous disease. Patients were classified according to the ISL classification and had a minimal follow-up of 2 years. Images were taken 60 minutes after the injection as a whole body scanning and fusion images of functional SPET and anatomical CT. Clinical and RNL results were not in accordance, and a specific RNL staging was established. The association of clinical and functional staging yields a new method to grade LE patients, and this staging correlated with treatment efficacy. RNL is an important tool in lymphology, and its association with the clinical evaluation offers a new grading system which may be able to delineate patients with good prognosis, patients at risk for a complex decongestive physiotherapy (CDP) failure, and patients who may benefit from other therapeutic protocols.

[Anomalies in myocardial contrast uptake revealed by multislice cardiac CT during acute myocarditis]. / Anomalies de la prise de contraste myocardique mises en évidence par le scanner cardiaque multicoupes au cours de myocardites aiguës. A propos de 2 cas.

Acute myocarditis can display many various clinical appearances. Endomyocardial biopsy is an invasive investigation for which the sensibility is insufficient in mild cases and when it is performed too early. Multislice cardiac CT with ECG synchronisation and injection of contrast medium allows visualisation of the coronary arteries and the study of myocardial contrast uptake. We report the cases of two patients with a mild myocarditis where multislice CT performed early showed multiple areas of increased myocardial contrast uptake consistent with a diffuse inflammatory disorder. Coronary angiography was normal in these two patients. Multislice cardiac CT could be a useful non-invasive investigation for the early diagnosis of this disease.

Incomplete recovery of lung perfusion after 3 months in patients with acute pulmonary embolism treated with antithrombotic agents. THESEE Study Group. Tinzaparin ou Heparin Standard: Evaluation dans l'Embolie Pulmonaire Study.

UNLABELLED: We assessed the time course of lung perfusion after 3 mo of anticoagulant therapy for acute pulmonary embolism (APE) on the basis of perfusion lung scan (PLS) findings for 157 patients included in the Tinzaparin ou Heparin Standard: Evaluation dans l'Embolie Pulmonaire Study (THESEE), a multicenter, randomized, nonmasked trial comparing standard, continuous, adjusted-dose intravenous heparin with once-daily, subcutaneous, low-molecular-weight heparin in patients with APE. METHODS: We calculated the percentage-of-vascular-obstruction score (PVOs) on PLSs on the day of diagnosis of APE (PVOsD1), on day 8 (PVOsD8), and after 3 mo (PVOsM3) and the mean relative changes in PVOs on day 8 versus the day of diagnosis and after 3 mo versus the day of diagnosis. RESULTS: Mean PVOsD1 +/- SD was 49% +/- 20%, PVOsD8 was 29% +/- 18%, and PVOsM3 was 19% +/- 18%. PVOsD1 was at least 50% in 49% of patients. Reperfusion did not correlate with age, importance of initial obstruction, or clinical severity of disease at inclusion in THESEE. Relative change after 3 mo versus at diagnosis was lower in the 87 patients with associated prior cardiopulmonary disease than in those without. In the 43 patients with a history of thromboembolic disease, neither mean PVOsD1 nor the time course of PVOs was different from those in patients without a history of thromboembolic disease. Residual defects after 3 mo were observed in 104 patients (66%), including 13 with a PVOs of at least 50%. CONCLUSION: These results emphasize the need for a control PLS at completion of anticoagulant therapy for APE, even in patients with full resolution of symptoms.

Reverse ventilation-perfusion mismatch in lung cancer suggests intrapulmonary functional shunting.

We report on a patient with squamous cell cancer of the left lung who was first considered ineligible for surgery because of severe hypoxemia. A ventilation-perfusion scan showed "reverse" ventilation-perfusion mismatch, with 20% of the total lung perfusion going to the left lung, which showed no ventilation with radioactive aerosols. This pattern suggested that the hypoxemia was due to intrapulmonary functional shunting and could therefore be improved by surgical resection of the tumor. Balloon occlusion of the left pulmonary artery resulted in an immediate rise in PaO2, indicating a right-to-left intrapulmonary shunt. After left pneumonectomy, PaO2 levels were normal. This patient provides an example of dysregulation of the pulmonary hypoxic vasoconstriction response in a non-small cell lung cancer. Lung cancer patients with severe hypoxemia should undergo ventilation-perfusion scanning to look for reverse ventilation-perfusion mismatch suggestive of intrapulmonary functional shunting.

Lung reperfusion injury after chronic or acute unilateral pulmonary artery occlusion.

Because the lungs receive their blood supply from both the pulmonary and bronchial systems, chronic pulmonary artery obstruction does not necessarily result in severe ischemia. Ischemia-reperfusion (IR) lung injury may therefore be attenuated after long-term pulmonary artery obstruction. To test this hypothesis, isolated left lungs of pigs were reperfused two days (acute IR group) or 5 wk (chronic IR group) after left pulmonary artery ligation and compared to those of sham-operated animals. The severity of IR-lung injury after 60 min ex vivo reperfusion of the left lung was assessed based on lung histology and measurements of filtration coefficient (Kfc), pulmonary arterial resistance (Rpa), and lung myeloperoxidase (MPO) activity. Marked bronchial circulation hypertrophy was seen in the chronic IR group. Hemorrhagic alveolar edema was found in all acute IR lungs but not in sham or chronic IR lungs. Compared with the sham-operated controls, Kfc and Rpa increased two-fold and threefold, and MPO 1.5-fold and twofold in the chronic and acute IR groups, respectively. In conclusion, IR-induced lung injury was markedly reduced when it occurred 5 wk after pulmonary artery ligation, probably because the systemic blood supply to the lung had time to develop, limiting ischemia.

Lung perfusion scans and hemodynamics in acute and chronic pulmonary embolism.

UNLABELLED: To assess the relationship between pulmonary vascular obstruction and hemodynamic status in acute pulmonary embolism (APE) and in chronic thromboembolic pulmonary hypertension (CTEPH), perfusion lung scan and hemodynamic measurements were obtained in 31 consecutive patients with APE and in 45 with CTEPH. METHODS: Lung scans were scored independently by two experience observers who determined the percentage of vascular obstruction (PVOs). Mean pulmonary artery pressure (PAP) and total pulmonary resistance (TPR) were obtained during right heart catheterization. In patients with APE, measurements were recorded within a 1-hr interval before and 12 hours after thrombolysis. This yielded 62 paired PVOs values with concomitant PAP and TPR measurements. In patients with CTEPH, data were recorded within a 3-day interval. RESULTS: Mean PVOs (%) values were similar in APE and CTEPH patients (59 +/- 13 vs. 58 +/- 15), whereas PAP and TPR were significantly higher in CTEPH patients (51 +/- 17 mmHg and 23 +/- 11 U/m2, respectively) than in APE patients (23 +/- 8 mmHg and 9 +/- 5 U/m2, respectively, p < 0.001). In APE patients, significant hyperbolic correlations were found linking PVOs with PAP and TPR (r = 0.75, p < 0.01 for PAP; r = 0.71, p < 0.01 for TPR). In CTEPH, there were no significant correlations between PVOs and PAP or TPR. For the same level of PVOs, patients with CTEPH had higher PAP and TPR value than patients with APE. CONCLUSION: In APE without prior cardiopulmonary disease, increases in PAP and TPR are correlated in a nonlinear fashion with the degree of pulmonary vascular obstruction as assessed by lung scanning. In CTEPH patients, the higher PAP and TPR values as compared to APE patients with comparable degrees of PVOs are consistent with previous reports that pulmonary hypertension in CTEPH is due not only to the obstruction of proximal pulmonary arteries but also to remodeling of small distal arteries in nonoccluded areas.

Correction of attenuation in SPECT with an attenuation coefficient map: a new method.

Attenuation coefficient (mu) maps, measured from transmission scan, are now becoming available. A simple method of attenuation correction is needed for routine implementation, however. Significant attenuation compensation can be mathematically obtained by dividing each actual pixel value of emission projections by the average of all the attenuation factors [exp (-sigma mu)] of all voxels along the same projection ray. This simple method, compatible with filtered back projection algorithms, was tested on simulations of cardiac and cerebral transaxial images on a Vax computer using the RECLBL library. In the models, the different structures received different activity and mu values. Three types of emission projections were generated: the ideal projections obtained by summation of the activity along each projection ray, the corresponding attenuated projections, and the projections corrected for attenuation. Comparison of projections on a pixel by pixel basis showed differences of less than 20% between the corrected and ideal projections. After reconstruction, both absolute and relative quantification were greatly improved by the correction of attenuation. Further validation of the method is in progress with actual patient data.

In vivo high-resolution MR imaging of the skin in a whole-body system at 1.5 T.

High-resolution magnetic resonance (MR) images of the skin were acquired with a whole-body MR system at 1.5 T by adding a specific imaging module: A saddle-shaped surface gradient coil was connected in place of one of the gradient coils of the system, and a surface radio-frequency coil with a 1.5-cm radius was placed at the center of the gradient coil. The images, acquired in 3 minutes 25 seconds, represent a field of view of 18 x 50 mm2, which corresponds to a pixel size of 70 x 390 micro2; the section thickness was 1.2 mm. With this spatial resolution, the different layers of the skin are clearly delineated: Epidermis appears as a high-signal-intensity layer, while dermis appears hypointense due to its very short T2. Pilosebaceous units appear as inclusions of epidermis inside dermis. The high quality of the images obtained enables in vivo MR characterization of skin.