Fig. 2

Performance evaluation of the total-body PET systems. a PET transverse and maximum intensity projection (MIP) images of a 64-year-old woman diagnosed with hepatocellular carcinoma. Left panels are reconstructed images with the clinical protocol via a conventional PET/CT scanner (uMI 780), and right panel is reconstructed images with 2 iterations and a 45-s acquisition via the uEXPLORER. The protocol with a 45-s scanning duration and 2 iterations using the uEXPLORER can provide equivalent image quality as the uMI 780 [35]. b MIP of the full-dose image and axial view of the serial dose reduction images generated by reduced count. Left: An FDG-avid micro-lesion in the liver of a 7-year-old patient with neuroblastoma, with an SUV_max of 4.35 on the full-dose image. The lesion is identifiable as reduced down to 1/20-dose and is un-diagnosable at 1/30-dose. Right: A micro-lesion in the subcapsular region of the liver in a 3-year-old patient with Burkitt Lymphoma is diagnosable in all dose reduction images [41]. c Dynamic scan is acquired after the injection of 496 MBq of ¹⁸F-FDG on a 60-year-old patient with metastatic colon cancer. Panels are 10-min reconstructions at 2.75- and 4.2-h post-injection using the PennPET scanner, respectively [33]. d Comparison of standard SUV image with parametric images of FDG influx rate K_i, fractional blood volume V_b, FDG delivery rate K₁ and volume of distribution V₀ images of a cancer patient. The images are shown as MIP maps [54]. It is worth mentioning that due to the different window widths, tumors may be more apparent in the parametric map than in the SUV map. In fact, there is no difference in tumor numbers between the two set of images