Multicenter external validation of two malignancy risk prediction models in patients undergoing 18F-FDG-PET for solitary pulmonary nodule evaluation.

OBJECTIVES: To achieve multicentre external validation of the Herder and Bayesian Inference Malignancy Calculator (BIMC) models. METHODS: Two hundred and fifty-nine solitary pulmonary nodules (SPNs) collected from four major hospitals which underwent 18-FDG-PET characterization were included in this multicentre retrospective study. The Herder model was tested on all available lesions (group A). A subgroup of 180 SPNs (group B) was used to provide unbiased comparison between the Herder and BIMC models. Receiver operating characteristic (ROC) area under the curve (AUC) analysis was performed to assess diagnostic accuracy. Decision analysis was performed by adopting the risk threshold stated in British Thoracic Society (BTS) guidelines. RESULTS: Unbiased comparison performed In Group B showed a ROC AUC for the Herder model of 0.807 (95 % CI 0.742-0.862) and for the BIMC model of 0.822 (95 % CI 0.758-0.875). CONCLUSIONS: Both the Herder and the BIMC models were proven to accurately predict the risk of malignancy when tested on a large multicentre external case series. The BIMC model seems advantageous on the basis of a more favourable decision analysis. KEY POINTS: • The Herder model showed a ROC AUC of 0.807 on 180 SPNs. • The BIMC model showed a ROC AUC of 0.822 on 180 SPNs. • Decision analysis is more favourable to the BIMC model.

Diagnostic accuracy of MDCT in the evaluation of patients with peritoneal carcinomatosis from ovarian cancer: is delayed enhanced phase really effective?

OBJECTIVE: To assess the diagnostic accuracy of delayed enhanced phase in addition to portal enhanced phase in MDCT imaging for depicting peritoneal carcinomatosis (PC) implants in patients with ovarian cancer. PATIENTS AND METHODS: We retrospectively reviewed double-phase, portal enhanced phase (PEP) and delayed enhanced phase (DEP), MDCT-examinations of 40 patients with clinical suspicion of recurrent PC from histopathologically-proven ovarian cancer, previously treated with both cytoreductive surgery and adjuvant/neoadjuvant chemotherapy. Image assessment was performed by three independent blinded readers (2 experienced and 1 less-experienced radiologists) in 3 different reading sessions: PEP (set A), DEP (set B), and PVP + DEP (set C). All CT-images were qualitatively assessed on the basis of the location of the lesion (based on Sugarbaker scheme), presence (indicating a confidence level for the diagnosis of PC), size and pattern. Reference standard both for detection and exclusion of PC was the evaluation of double-phase MDCT exams performed by two experienced readers in consensus, knowing clinical and laboratoristic parameters as well as previous and subsequent imaging (follow-up minimum of 12 months). Sensitivity, specificity, PPV, NPV and diagnostic accuracy of each reader for each reading session were calculated and compared. A subgroup analysis based on lesion pattern was also performed. RESULTS: On a total of 507 abdominal-pelvic sites evaluated, PC was found in 182 regions (35.9%). When considering experienced radiologists, no statistically significant differences (p>0.05) were found between the different sets of images. The analysis by less-experienced radiologist showed lower statistical results, which significantly improved when both PEP and DEP were evaluated. In the subgroup analysis, DEP showed significantly higher statistical results in the case of micronodular patterns. CONCLUSIONS: Our results indicate that the CT-acquisition protocol in patients with ovarian cancer for tumor staging should be based on portal phase alone, with a significant radiation dose reduction, whereas the addition of delayed phase images is useful for less-experienced readers.