Assessment of Response to Neoadjuvant Chemoradiotherapy by 18F-FDG PET/CT in Patients With Locally Advanced Esophagogastric Junction Adenocarcinoma.

PURPOSE: The outcome of locally advanced adenocarcinoma of the esophagogastric junction (AEG) treated with preoperative chemoradiotherapy is heterogeneous, and favorable response to this treatment is a key factor in the patient's prognosis. The aim of this study was to evaluate F-FDG PET/CT in assessing metabolic response in patients with AEG. MATERIALS AND METHODS: This prospective study evaluated all consecutive patients with potentially operable locally advanced AEG who were candidates for neoadjuvant chemoradiotherapy. PET/CT and contrast-enhanced thoracoabdominal CT were performed at baseline and 2 weeks after completion of chemoradiotherapy for response evaluation. The response rate was assessed using Response Evaluation Criteria in Solid Tumors criteria for contrast-enhanced thoracoabdominal CT and Positron Emission Tomography Response Criteria in Solid Tumors criteria for PET/CT. The regression rate was assessed using a 5-grade histopathology scoring system of the surgically resected tumor. Metastatic lesions were confirmed by histopathology examination or imaging and clinical follow-up at 6 months. RESULTS: A total of 40 cases were finally included in the study. Distant metastases were found in the baseline PET/CT in 6 of 40 cases (retroperitoneal [2] or mediastinal/hiliar [1] lymph nodes and liver [2] or bone [1] metastases) and were therefore excluded from surgery. Pathologic response correlated with the ΛSUVmax threshold of ≤45% (P = 0.033). CT response correlated well with both the baseline SUVmax (P = 0.039) and the ΛSUVmax (P = 0.001). Five-year survival curves for AEG correlated with the ΛSUVmax using a threshold of ≤45% for both progression-free and overall survival. CONCLUSIONS: F-FDG PET/CT is useful for diagnosing nonsuspected metastasis before neoadjuvancy in potentially operable AEG. The ΛSUV correlates with pathologic response and is a long-term independent prognostic factor of survival.

AUC/MIC Pharmacodynamic Target Is Not a Good Predictor of Vancomycin Efficacy in Methicillin-Resistant Staphylococcus aureus Experimental Endocarditis.

The aim of this in vivo study was to compare the efficacy of vancomycin at standard doses (VAN-SD) to that of VAN at adjusted doses (VAN-AD) in achieving a VAN area under the curve/MIC ratio (AUC/MIC) of ≥400 against three methicillin-resistant Staphylococcus aureus (MRSA) strains with different microdilution VAN MICs in an experimental endocarditis model. The valve vegetation bacterial counts after 48 h of VAN therapy were compared, and no differences were observed between the two treatment groups for any of the three strains tested. Overall, for VAN-SD and VAN-AD, the rates of sterile vegetations were 15/45 (33.3%) and 21/49 (42.8%) (P = 0.343), while the medians (interquartile ranges [IQRs]) for log10 CFU/g of vegetation were 2 (0 to 6.9) and 2 (0 to 4.5) (P = 0.384), respectively. In conclusion, this VAN AUC/MIC pharmacodynamic target was not a good predictor of vancomycin efficacy in MRSA experimental endocarditis.

Optimum threshold estimation based on cost function in a multistate diagnostic setting.

In the diagnostic area, the usual setting considers two populations: nondiseased and diseased. The use of the standard ROC analysis methodology is well established. Sometimes, however, diagnostic problems inherently include more than two classification states. For example, 'yes, uncertain, no' or 'low, normal, high'. Here we consider a three-normal distribution setting and derive estimators for the optimum thresholds between states based on a cost function. These estimators can be extended for clinical contexts with more than three states. This approach is well known for the two-state setting and its advantage lies in the fact that it accounts for the specific context's properties, such as disease prevalence and classification costs. Here we calculated the variance of the estimators by the use of parametric methods on nonlinear equations and we constructed confidence intervals accounting for possible uncertainty in the threshold estimation. We conducted a simulation study to assess the performance of these estimators and the confidence intervals. Comparisons with the naive threshold estimation method of joining the distributions two-by-two and applying standard ROC techniques proved that the latter method is not reliable for all parameter combinations and should be avoided.

Assessment of radiofrequency ablation of lung metastasis from colorectal cancer using dual time-point PET/CT.

A 70-year-old man with operated colorectal cancer relapsed with a solitary lung metastasis. Dual time-point PET/CT performed at 60' (standard images) and after 2 hours (delayed images) showed focal uptake in the lung nodule. A second uptake in the liver dome was also visualized only in the delayed images. Radiofrequency of the lung metastasis was performed by CT-fluoroscopy guide. A PET/CT 1 month after radiofrequency showed significant reduction of activity in the delayed images, and the uptake at 3 months was virtually normal. A fine-needle biopsy of the liver lesion confirmed the final diagnosis of metastasis from adenocarcinoma.

Technetium 99m-labeled tetrofosmin and iodine 123-labeled metaiodobenzylguanidine scintigraphy in the assessment of transmyocardial laser revascularization.

OBJECTIVE: Transmyocardial laser revascularization is a new technique that improves symptoms in patients with refractory angina not amenable to conventional revascularization. The aim of this study was to assess whether transmyocardial laser revascularization produces changes in innervation, perfusion scintigraphy, or both that could explain the benefit to patients. METHODS: Sixteen patients (12 men and 4 women; mean age, 60 +/- 8 years) with coronary artery disease were studied. Transmyocardial laser revascularization was performed in 39 myocardial areas supplied by a stenotic vessel. A technetium 99m-labeled tetrofosmin stress-rest tomographic scan and iodine 123-labeled metaiodobenzylguanidine planar scans were performed before and after transmyocardial laser revascularization (3 and 12 months later) to evaluate myocardial perfusion and innervation. Stress and rest perfusion images were quantified on a polar map. Ischemia uptake was also defined as the difference between rest and stress uptake for each area. Innervation planar images were visually analyzed and semiquantified. RESULTS: A significant decrease in angina class from baseline was observed at 3, 6, and 12 months after transmyocardial laser revascularization (P <.005). A significant decrease in ischemia uptake was also found between the pre-transmyocardial laser revascularization and the post-transmyocardial laser revascularization studies in treated areas (P <.001). A significant improvement in stress myocardial perfusion at 3 and 12 months after transmyocardial laser revascularization was only found in treated areas that were considered ischemic in the pre-transmyocardial laser revascularization study (P <.05). At 3 months, a significant myocardial innervation worsening was observed in treated areas (P <.001), with partial recovery at 12 months (P <.05). CONCLUSION: The transmyocardial laser revascularization mechanism involves both perfusion improvement and denervation, mainly at 3 months, that partially recovered at 12 months.