Standard operating procedure (SOP) for cervical ultrasound cine loop video sequences in the follow-up of differentiated thyroid carcinoma (DTC)

Abstract Rationale and objectives Cervical ultrasound (US) is crucial in the follow-up of differentiated thyroid cancer (DTC). However, there are no guidelines for its acquisition and documentation, particularly concerning the role of additional video sequences, known as US cine loops (UCL). The aim of this study is to examine the clinical relevance (CR) of a new Standard Operating Procedure (SOP) for cervical UCL in DTC follow-up. Materials and methods A retrospective analysis was conducted on all UCL examinations of DTC follow-up patients at a tertiary care center between January 2010 and February 2018 to determine their clinical significance. The patients were divided into two groups: those with no documented CR (UCL-nCR) and those with documented CR (UCL-CR). The study reviewed the respective written medical US reports that were validated by experienced residents. The UCL-CR were categorized in: confirmation of a suspicious finding that was identified during conventional live US (UCL-CRcon), identification of a suspicious finding that was not identified during conventional live US (UCL-CRide), and invalidation of a suspicious finding that was identified during conventional live US (UCL-CRinv). Results A total of 5512 UCLs in 652 DTC patients were analyzed, with 71.5% women and a mean age of 50 years. More than 90% of the tumors were low-risk at initial staging. The mean number of UCLs per patient was 8.5 ± 4.6. Overall, 95 cases of UCL-CR were identified in 82 patients (12.6%), with a patient-based number needed to scan of 8. UCL-CRinv was the most common type of UCL-CR, accounting for 77 (81.1%) of cases. The occurrences of 12 UCL-CRcon (12.6%) and 6 UCL-CRide (6.3%) were correspondingly less frequent. The diagnosis of UCL-CR was confirmed in 91.6% of cases during the clinical course. Conclusions In 12.6% of the patients, the additional acquisition and archiving of cervical UCL revealed clinical relevance in the course of DTC disease. The invalidation of suspicious findings through the retrospective analysis of former UCL occurred as the most significant benefit of this method. The UCL SOP can be easily and quickly integrated into the US workflow.