Search

Purpose: Currently, no consistent guidelines for CT scans used within PET/CT examinations are available. This systematic review provides an up-to-date overview of studies to answer the following questions: What are the specific CT protocols used in PET/CT? What are the possible purposes of requiring a CT study within a PET/CT scan? Is the CT protocol obtained from a dosimetric optimisation study? Materials and method: PubMed/MEDLINE, Cochrane Library, Embase and Scopus were systematically searched for relevant studies in accordance with the PRISMA statement. The literature search was conducted from January 2007 until June 2019. Data derived from studies were standardized in order to reduce possible biases, and they were divided into clinically homogeneous subgroups (adult, child or phantom). Subsequently, we divided the CT protocol intents into 3 types (anatomic localization only, attenuation correction only and diagnostic purpose). A narrative approach was used to summarise datasets and to investigate their heterogeneity (due to medical prescription methodology) and their combination in multiseries CT protocols. When weighted computed tomography dose index (CTDIw) was available, we calculated the volumetric computed tomography dose index (CTDIvol) using the pitch value to make the results uniform. Eventually, the correlation between protocol intents and CTDIvol values was obtained using a Kruskal–Wallis one-way ANOVA statistical test. Result: Starting from a total of 1440 retrieved records, twenty-four studies were eligible for inclusion in addition to two large multicentric works that we used to compare the results. We analyzed 87 CT protocols. There was a considerable range of variation in the acquisition parameters: tube current–time product revealed to have the most variable range, which was 10–300 mAs for adults and 10–80 mAs for paediatric patients. Seventy percent of datasets presented scans acquired with tube current modulation, 9% used fixed tube current and in 21% of them, this information was not available. Dependence between mean CTDIvol values and protocol intent was statistically significant (p = 0.002). As expected, in diagnostic protocols, there was a statistically significant difference between CTDIvol values of with and without contrast acquisitions (11.68 mGy vs 7.99 mGy, p = 0.009). In 13 out of 87 studies, the optimisation aim was not reported; in 2 papers, a clinical protocol was used; and in 11 works, a dose optimisation protocol was applied. Conclusions: According to this review, the dose optimisation in PET/CT exams depends heavily on the correct implementation of the CT protocol. In addition to this, considering the latest technology advances (i.e. iterative algorithms development), we suggest a periodic quality control audit to stay updated on new clinical utility modalities and to achieve a shared standardisation of clinical protocols. In conclusion, this study pointed out the necessity to better identify the specific CT protocol use within PET/CT scans, taking into account the continuous development of new technologies. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To profile and correlate KRAS mutations with outcome in stage III colon cancer (CC) patients who underwent adjuvant chemotherapy following curative resection surgery. PATIENTS AND METHODS: In this retrospective study, eligible patients were those with resected stage III CC who underwent 6-months adjuvant chemotherapy, either with fluoropyrimidine monotherapy (FP) or with oxaliplatin-based regimens (O-FP). Disease-free survival (DFS) and overall survival (OS) were analyzed and computed using the Kaplan-Meier method and the log-rank test. RESULTS: The study population included 148 patients (n=65 FP and n=83 O-FP). We identified KRAS mutations in 41/148 (27%) patients, of which 18 (44%) received FP and 23 (56%) O-FP. Five-year DFS and OS were significantly higher in patients with KRAS wild-type vs. mutant [DFS: 78 vs. 56%, HR: 0.47 (95% CI: 0.25; 0.87), p=0.01; OS: 73 vs. 68%, HR: 0.44 (95% CI: 0.21; 0.88), p=0.01]. In patients treated with FP, the 5-year DFS and OS was significantly improved in the KRAS wild-type vs. mutant group, respectively [DFS: 80 vs. 43%, HR: 2.88 (95% CI: 0.67; 3.76), p=0.014; OS: 85 vs. 68%, HR: 0.27 (95% CI: 0.10; 0.73), p=0.005]. Conversely, 5-year DFS and OS were not statistically different for patients with KRAS wild-type vs. mutations treated with O-FP, respectively [DFS: 78 vs. 65%, HR: 1.59 (95% CI: 0.67; 3.76), p=0.281; OS: 80 vs. 75%, HR: 0.73 (95% CI: 0.55; 2.12), p=0.57)]. CONCLUSIONS: O ur r esults s uggest t hat c uratively resected stage III CC patients exhibiting wild-type KRAS status might benefit from FP alone. Conversely, an oxaliplatin-containing regimen should be recommended in KRAS mutated patients. [ABSTRACT FROM AUTHOR]