Ultra-short time imaging of total-body PET/CT for cancer pain-induced untenable body position

Abstract

A 55-year-old male patient diagnosed with advanced stage breast cancer was scheduled PET/CT examination for pretreatment disease evaluation. However, because of primary and metastatic lesions-induced severe cancer pain, motionless body position cannot be maintained for a relatively long time to complete PET signal acquisition. Then, the patient was transferred to total-body PET/CT for tentative imaging, in which the entire body is scanned in a single shot using a 194-cm axial PET scanner. Motionless body position was maintained for 2 min, and reconstruction of PET images was conducted based on the signal data of the first 2 min. The reconstructed PET images clearly presented the extensive primary tumor that invaded skin, adjacent ribs, and intercostal muscles, and wide-spread distant metastatic lesions including intracranial, pulmonary, pleura, liver, multiple lymphnode, and bone metastases. The image quality and detectability for small lesions were also satisfied with sufficient signalto-noise ratio (SNR) and contrast-to-noise ratio (CNR) that could be easily distinguished by visual. Overall, the diagnostic performance of the ultra-short time imaging were sufficient for accurate disease evaluation. Although there are several recent studies evaluating the total-body PET/CT’s imaging and detection capabilities in standard models [1, 2], to our knowledge, this is the first case report on the actual practice of clinical management of patients who have contraindications for conventional PET examination. The total-body PET has a 194-cm long axial fieldof-view, which allows simultaneous detection of the coincidence events from the entire body, and due to the wide acceptance angle, the sensitivity of the PET scanner is substantially improved [3]. In addition, the fact that the total-body PET only needs one bed acquisition instead of 6 to 8 bed times in conventional PET scanner could also enable the conduction of ultra-short time imaging. It needs to mention that, in this case, it is also feasible to conduct one bed site imaging of breast and chest by conventional PET/CT in 2 min, which can make diagnosis of metastases and acquire images of the most important region. In addition, bone metastases could be diagnosed by chest and abdomen CT alone. The alternative management method is full of application value for the patient if the PET imaging is indispensable with only conventional PET/CT that could be used. Meanwhile, it also has some disadvantages, as PET imaging of other sites and accurate diagnosis of numerous small lesions in these regions would be sacrificed, or else, the suffering of the patient would be largely increased if sectional PET scans were conducted for the rest body parts which required the maintainance of tenable body position for another 5 to 7 independent 2 min. Untenable body position due to cancer pain or other pathological conditions such as claustrophobia or cardiopulmonary insufficiency is often encountered by nuclear medicine physicians, and generally, the patients have to quit PET examination because of unqualified images. Children is another group of patients with difficulties in maintaining motionless body position. The application of ultra-short time imaging in children patients could reduce the frequency of tranquilizer and improve the examination experience. Although uncommon, patients with compulsive movements due to psychological disorders or brain metastases could also need PET imaging, and total-body PET/CT could assist them with relief in completing the examination or at least reduce the constraint This article is part of the Topical Collection on Image of the month.