Digital PET/CT: a new intriguing chance for clinical nuclear medicine and personalized molecular imaging

Abstract

Clinical PET/CT is a well-known useful tool for the in vivo noninvasive quantitative imaging of physiologic and pathologic processes [1]. Actually, the key role of PET/CT in cancer staging and therapeutic responses to personalized treatments is well established; it is an essential imaging modality not only in oncology but also in neuroscience and in all the applications of molecular imaging. In recent years, there have been multiple advances in PET/CT scanners: new hardware, software, and acquisition methods to improve image quality [2]. Nevertheless, till now PET detectors have been mainly based on photomultiplier tubes (PMT), which have well-known advantages but also several limitations that affect, in particular, small lesions detection [3]. The introduction of digital detectors in PET/CT scanners may represent an important improvement in this diagnostic technology [4].In this issue of EJNMMI, Lopez-Mora et al.[5] present a step forward in this field, comparing image quality and lesion detection capability between a digital (d) and an analog (a) PET/CT system in 100 patients with oncologic diseases who were prospectively included in this study. The patients consecutively underwent a single day, dual imaging protocol (d and aPET/CT) after a i.v. injection of either FDG or fluorocholine. The first PET/CT was performed 60 min after the i.v. injection of the radiopharmaceutical, and the second imaging dataset was acquired with a mean time delay of 50 ± 14 min. In the patients referred for an initial assessment (n = 58), the dPET/CT was performed first, while in the patients who were evaluated for therapy monitoring, the aPET/CT was firstly acquired. Three nuclear medicine physicians evaluated image quality using a 4-point scale (−1, poor to 2, excellent) and detection capability by counting the number of lesions with increased uptake of the radiopharmaceutical. In 54% of patients, dPET/CT allowed a better image quality than aPET/ CT; in the remaining 46 patients, image quality did not significantly differ between both devices. Regarding lesion detection capability, dPET/CT was able to visualize lesions in three patients in whom the a system resulted negative; moreover, in 19 out of 80 cases which were positive at aPET/CT imaging, the dPET/CT detected more lesions. In these 22 patients, all the lesions visualized only by means of the dPET/CT were < 1 cm in size: eight were in the lungs, eight in lymph-nodes, six in the liver, four in bones, and one in seminal vesicles, in the breasts and in the skin, respectively. It is worth noting that dPET/CT changed staging in 32% of these patients (7 out of 22).In the same group of 100 oncological patients, another recent study was conducted to assess whether dPET/CT impact on the quantification of SUVmax in target lesions (the most metabolically active in each case) and in reference regions (liver and mediastinal blood pool) in comparison to aPET/CT [6]. The findings of this paper indicate that SUVmax of the target lesions and mediastinal blood pool measured by the d system w...

Digital PET/CT allows for shorter acquisition protocols or reduced radiopharmaceutical dose in [18F]-FDG PET/CT

“…As described in the introduction, digital PET/CT represents a step forward in molecular imaging, with increasing numbers of publications confirming the favourable performance characteristics for such scans in comparison to previous-generation analogue systems [ 1 , 16 ], including increased lesion detection and sensitivity [ 1 , 3 , 4 , 13 , 17 ]. Previous authors have reported head-to-head studies comparing digital and analogue systems, showing both improved image quality and upstaging of individuals [ 10 ], as well as improved recovery (as shown by higher SUV values) and lesion sharpness [ 3 , 6 ].…”

SNMMI Procedure Standard/EANM Practice Guideline on Pediatric18F-FDG PET/CT for Oncology 1.0

“…The administered activity should be the lowest possible dose that will produce diagnostic image quality. This, in part, depends on the acquisition techniques and the sensitivity of the PET/CT scanner (76)(77)(78)(79). The administered activity should follow the 2016 Update of the North American Consensus Guidelines for Pediatric Administered Radiopharmaceutical Activities and the 2016 EANM pediatric Dosage Card (80)(81)(82).…”

Current Perspectives on 89Zr-PET Imaging

“…To reduce the radiation dose, a groundbreaking improvement in PET technology is necessary. Digital PET is a good example of successful dose reduction due to the enhanced sensitivity from using a PET equipped with digital silicon photomultipliers [ 121 ]. The high sensitivity of digital PET makes it possible to acquire images either with a shorter scan time or with a lower radiopharmaceutical dose.…”