Total-Body PET/CT "Twins" Accelerate Research and Cut Radiation Dose at King's College London
核心洞察
King's College London & Guy's and St Thomas' PET Centre acquired two identical Biograph Vision Quadra (搜索) total-body PET/CT scanners in late 2024 and early 2025, nicknamed the "twins."
The scanners' high sensitivity enables roughly half the radiation dose for patients and staff while scanning patients much faster, improving clinical efficiency.
The TOTEM study, with 1,400 patients recruited, is developing standardized total-body PET/CT protocols and has validated ultra-low-dose CT approaches within about six weeks.
King's College London & Guy's and St Thomas' PET Centre (KCL & GSTT PET Centre) has put into operation two identical Biograph Vision Quadra (搜索) total-body PET/CT scanners—affectionately nicknamed the "twins"—acquired in late 2024 and early 2025. According to Prof. Alexander Hammers, head of the PET Centre, and Gary Cook, professor of molecular imaging at KCL School of Biomedical Engineering & Imaging Sciences, the investment marks a major milestone that has made clinical routine diagnostics "way more efficient" while opening a range of promising research avenues.
One of the two scanners was competitively awarded, in partnership with Imperial College London, through a grant scheme provided by the Medical Research Council National PET Imaging Platform, while the second was financed by KCL. The decision to acquire two identical total-body scanners was strategic, based on experiences at other PET/CT centers.
Clinical Efficiency and Dose Reduction
The Biograph Vision Quadra (搜索)'s high sensitivity means that less tracer and less radiation are needed, and scans can be completed quickly. Hammers explained the dual benefit: "Now we can split the benefit of Biograph Vision Quadra between patients and the Centre. We can scan patients much faster, and they are getting roughly half of the dose they were getting before—which also means our staff are getting less dose."
The economics also favored the investment. Cook co-authored a scientific paper analyzing the overall costs of using one or two total-body PET/CT scanners over a 10-year period, compared to extending the working day with standard short axial field of view PET/CT scanners. "In most situations, the total-body PET/CT turned out to cost less, despite the scanner's initial costs. This is because of increased throughput, and because of savings on staff, radioactivity, and so on."
Efficient Use of Radiopharmaceuticals
Having two total-body PET/CTs also supports more efficient use of GMP-manufactured radiopharmaceuticals, a pressing concern given what Hammers described as "an absolute dearth of radiotracers in the UK." He cited the example of [11C]methionine (搜索) PET/CT: "We have managed to do one Carbon-11 synthesis and scan four dynamic [11C]methionine patients, thanks to the two scanners. That's absolutely astounding. Other centers need [18F]fluoroethyltyrosine ([18F]FET) to achieve the same."
The TOTEM Study
A flagship project is the TOTEM (Total Body PET—Exploring new iMaging protocols for clinical research) study, which has recently reached 1,400 recruited patients. Cook explained that TOTEM was designed to maximize research use of clinical examinations, with the goal of developing and validating standardized protocols for the total-body PET/CT scanner—a process still in its infancy given that long axial field of view (LAFOV) scanning is a recent technology.
TOTEM research is deeply embedded into routine workflows. "For example, we can ask a patient to have a dynamic scan after their injection rather than waiting in the uptake room, so we can develop protocols for kinetic analyses. Or we can do delayed scans with a low-dose CT," Cook said. Currently, eight substudies are running within the TOTEM framework, with at least eight others in preparation.
One substudy tested various ultra-low-dose CT protocols using tin filters to minimize radiation exposure. Hammers noted these projects were "extremely successful," adding: "We could verify, in real patients, the effects we had already predicted together with our colleagues from Siemens Healthineers (搜索), who are our embedded scientists." He emphasized the speed of the work: "But within TOTEM, we have been able to acquire the necessary data within six weeks or so. To my mind, it is the first time that talking about PET pilot studies really makes sense."
Predicting Treatment Resistance with [18F]FSPG
An oncology trial approaching completion uses the cutting-edge imaging tracer [18F]fluoropropyl-L-glutamic acid ([18F]FSPG (搜索)) in patients with head-and-neck cancers (搜索). According to Cook, [18F]FSPG can measure the ability of cancer cells to evade oxidative stress during treatment—the better cancer cells evade oxidative stress, the more likely they are to be treatment resistant. The goal is to use FSPG imaging to predict early which cancers will be resistant.
"We now know that within four weeks of starting the treatment, we can predict what the clinical treatment outcome will look like on a standard FDG-scan after 12 weeks," Cook said. He added that FSPG imaging might, in the longer run, revolutionize therapeutic monitoring in oncology, though more research is needed. The trial examined the kinetics of FSPG uptake into the tumor—"something that had never been done before"—and produced a model of FSPG uptake that "perhaps challenges assumptions we had before from animal work."
Future Directions
The centre is planning further expansions, including the rollout of cardiac PET/CT using rubidium-82 (82Rb) and imaging with Fluorine-18-labeled sodium fluoride ([18F]NaF) for bone lesion detection in oncology, as well as infectious disease and atherosclerosis imaging. Starting in 2027, GSTT will provide a dedicated pediatric oncology service for South London, adding another 300 to 400 scans per year to the 10,000 already being done. "It is really a very exciting time to be in PET," said Hammers.