Posttreatment surveillance for the recurrence of head and neck squamous cell carcinoma (HNSCC) is a diagnostic challenge. Tissue distortion from radiation and surgery can obscure early detection of recurrence by conventional follow-up approaches such as physical examination, CT, and MRI. Several studies have shown that ¹⁸F-FDG PET may be an effective technique for the detection of persistent, recurrent, and distant metastatic HNSCC after treatment. The aim of this prospective study was to determine the benefits of hybrid ¹⁸F-FDG PET/CT in detecting a subclinical locoregional recurrence of HNSCC and distant metastases. The study patients were considered cured of HNSCC on the basis of 12 mo of negative findings on conventional follow-up. We also assessed the diagnostic accuracy of ¹⁸F-FDG PET/CT in these patients. Methods: Ninety-one patients cured of HNSCC without any clinical evidence of recurrence were included. Whole-body ¹⁸F-FDG PET/CT examination was performed 11.6 ± 4.4 mo after the end of the treatment. The gold standard was histopathology or 6 mo of imaging follow-up. Results: The whole-body ¹⁸F-FDG PET/CT examinations had negative results in 52 patients and positive results in 39. Nine of these patients who exhibited abnormal ¹⁸F-FDG uptake in the head and neck area did not have recurrent HNSCC (false-positive). Thirty had proven recurrence. The sensitivity and specificity of ¹⁸F-FDG PET/CT in this study for the diagnosis of HNSCC recurrence were 100% (30/30) and 85% (52/61), respectively. The positive predictive value was 77% (30/39). The negative predictive value was 100% (52/52). The overall accuracy was 90% (82/91). Conclusion: The results of our study confirm the high effectiveness of ¹⁸F-FDG PET/CT in the assessment of HNSCC recurrence and suggest that ¹⁸F-FDG PET/CT is more accurate than conventional follow-up physical examination alone in the assessment of recurrence after previous curative treatment for HNSCC and could be proposed systematically at 12 mo of the usual follow-up.

Point-spread function (PSF) or PSF + time-of-flight (TOF) reconstruction may improve lesion detection in oncologic PET, but can alter quantitation resulting in variable standardized uptake values (SUVs) between different PET systems. This study aims to validate a proprietary software tool (EQ.PET) to harmonize SUVs across different PET systems independent of the reconstruction algorithm used.

Differences of computed tomography pulmonary angiography versus ventilation-perfusion lung scan in pregnant patients with suspected acute pulmonary embolism are not well-known, leading to ongoing debate on which test to choose. We searched in PUBMED, EMBASE, Web of science and Cochrane library databases and identified all relevant articles and abstracts published up to October1st 2017. We assessed diagnostic efficiency, frequency of non-diagnostic results and radiation exposure for patient and fetus. We included 13 studies for the diagnostic efficiency analysis, 30 for non-diagnostic results analysis and 22 for radiation exposure analysis. Pooled rate of false negative test results was 0% for both imaging strategies with overlapping confidence intervals. The pooled rate of non-diagnostic results with computed tomography pulmonary angiography and ventilation-perfusion lung scan were 12% (95%CI 8-17) and 14% (95%CI 10-18), respectively. Reported maternal and fetal radiation exposure doses were well below the safety threshold, but could not be compared between computed tomography pulmonary angiography and ventilation-perfusion lung scan given the lack of high quality data. Both imaging tests seem equally safe to rule out PE in pregnancy. We found no significant differences in efficiency and radiation exposures between computed tomography pulmonary angiography and ventilation-perfusion lung scan although direct comparisons were not possible.