A major disadvantage of 18 F-FDG PET involves poor detection of small lesions and lesions with low metabolism, caused by limited spatial resolution and relatively large image voxel size. As spatial resolution and sensitivity are better in new PET systems, it is expected that small-lesion detection could be improved using smaller voxels. The aim of this study was to test this hypothesis using a state-of-the-art time-of-flight PET/CT device. Methods: 18 F-FDG PET scans of 2 image-quality phantoms (sphere sizes, 4-37 mm) and 39 consecutive patients with lung cancer were analyzed on a time-of-flight PET/CT system. Images were iteratively reconstructed with standard 4 · 4 · 4 mm voxels and smaller 2 · 2 · 2 mm voxels. For the phantom study, we determined contrast-recovery coefficients and signal-to-noise ratios (SNRs). For the patient study, 18 F-FDG PET-positive lesions in the chest and upper abdomen with a volume less than 3.0 mL (diameter, ,18 mm) were included. Lesion mean and maximum standardized uptake values (SUV mean and SUV max , respectively) were determined in both image sets. SNRs were determined by comparing SUV max and SUV mean with background noise levels. A subanalysis was performed for lesions less than 0.75 mL (diameter, ,11 mm). For qualitative analysis of patient data, 3 experienced nuclear medicine physicians gave their preference after visual side-by-side analysis. Results: For phantom spheres 13 mm or less, we found higher contrast-recovery coefficients and SNRs using small-voxel reconstructions. For 66 included 18 F-FDG PET-positive lesions, the average increase in SUV mean and SUV max using the small-voxel images was 17% and 32%, respectively (P , 0.01). For lesions less than 0.75 mL (21 in total), the average increase was 21% and 44%, respectively. Moreover, averaged over all lesions, the mean and maximum SNR increased by 20% and 27%, respectively (P , 0.01). For lesions less than 0.75 mL, these values increased up to 23% and 46%, respectively. The physicians preferred the small-voxel reconstructions in 76% of cases. Conclusion: Supported by a phantom study, there was a visual preference toward 18 F-FDG PET images reconstructed with 2 · 2 · 2 mm voxels and a profound increase in standardized uptake value and SNR for small lesions. Hence, it is expected that small-lesion detection improves using smallvoxel reconstructions. Whole-body 18 F-FDG PET integrated with CT is widely used for primary tumor analysis and mediastinal lymph node staging in patients with non-small cell and small cell lung cancer (1,2). For these patients, accurate lymph node staging is of high importance because both prognosis and therapeutic management depend on the tumor stage (3). A major disadvantage of 18 F-FDG PET involves poor detection of small lesions and lesions with low metabolism. With a sensitivity of 76% and specificity of 88% (4), PET/ CT is less sensitive for nodal involvement of small nodes (diameter, ,10 mm) (3,5). This poor detection is caused by limited spatial resolution and sensitivity (3,6). To impro...

PurposeNew X-ray technology providing new image processing techniques may reduce radiation exposure. The aim of this study was to quantify this radiation exposure reduction for patients during pacemaker and implantable cardioverter defibrillator (ICD) implantation.MethodsIn this retrospective study, 1185 consecutive patients who had undergone de novo pacemaker or ICD implantation during a 2-year period were included. All implantations in the first year were performed using the reference technology (Allura Xper), whereas in the second year, the new X-ray technology (AlluraClarity) was used. Radiation exposure, expressed as the dose area product (DAP), was compared between the two time periods to determine the radiation exposure reduction for pacemaker and ICD implantations without cardiac resynchronization therapy (CRT) and with CRT. Procedure duration and contrast volume were used as measures to compare complexity and image quality.ResultsThe study population consisted of 591 patients who had undergone an implantation using the reference technology, and 594 patients with the new X-ray technology. The two groups did not differ in age, gender, or body mass index. The DAP decreased with 69 % from 16.4 ± 18.5 to 5.2 ± 6.6 Gy cm2 for the non-CRT implantations (p < 0.001). The DAP decreased with 75 % from 72.1 ± 60.0 to 17.8 ± 17.4 Gy cm2 for the CRT implantations (p < 0.001). Nevertheless, procedure duration and contrast volume did not differ when using the new technology (p = 0.09 and p = 0.20, respectively).ConclusionsIntroduction of new X-ray technology resulted in a radiation exposure reduction of more than 69 % for patients during pacemaker and ICD implantation while image quality was unaffected.