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.

Assessing probability of malignancy in solid solitary pulmonary nodules with a new Bayesian calculator: improving diagnostic accuracy by means of expanded and updated features.

OBJECTIVES: A crucial point in the work-up of a solitary pulmonary nodule (SPN) is to accurately characterise the lesion on the basis of imaging and clinical data available. We introduce a new Bayesian calculator as a tool to assess and grade SPN risk of malignancy. METHODS: A set of 343 consecutive biopsy or interval proven SPNs was used to develop a calculator to predict SPN probability of malignancy. The model was validated on the study population in a "round-robin" fashion and compared with results obtained from current models described in literature. RESULTS: In our case series, receiver operating characteristic (ROC) analysis showed an area under the curve (AUC) of 0.893 for the proposed model and 0.795 for its best competitor, which was the Gurney calculator. Using observational thresholds of 5% and 10% our model returned fewer false-negative results, while showing constant superiority in avoiding false-positive results for each surgical threshold tested. The main downside of the proposed calculator was a slightly higher proportion of indeterminate SPNs. CONCLUSIONS: We believe the proposed model to be an important update of current Bayesian analysis of SPNs, and to allow for better discrimination between malignancies and benign entities on the basis of clinical and imaging data. KEY POINTS: • Bayesian analysis can help characterise solitary pulmonary nodules • Volume doubling time (VDT) is a good predictor of malignancy • A VDT of between 25 and 400 days is highly suggestive of malignancy • Nodule size, enhancement, morphology and VDT are the best predictors of malignancy.

Limited value of logistic regression analysis in solid solitary pulmonary nodules characterization: a single-center experience on 288 consecutive cases.

BACKGROUND AND OBJECTIVES: Preoperative characterization of the solitary pulmonary nodule is a delicate task faced by surgeons, radiologists, and clinicians. Mathematical models have been developed to overcome subjectivity. The Mayo Clinic model was suggested in the latest ACCP evidence-based clinical practice guidelines for the preoperative risk assessment of solitary pulmonary nodule malignancy. The aim of the study is to assess the validity of the Mayo Clinic model in a current continuous case series of biopsy-proven nodules. METHODS: The Mayo Clinic model was applied to estimate probability of malignancy in 288 consecutive cases in this single-center retrospective study. RESULTS: ROC curve analysis returned an AUC of 0.767, while analysis performed on 158 malignant nodules showed a mean predicted risk value of 38.15%. In our clinical setting, using a risk observational threshold set at 5% and a risk surgical threshold set at 60%, there would have been 4 cases of unnecessary surgery (false positives) at the cost of 13 cases of cancer progression (false negatives), while 68.75% of all nodules would have received non-decisional values. CONCLUSIONS: Surgeons should be aware that current data shows how the Mayo Clinic model is of little use in preoperative nodule characterization.

MR imaging and MR cholangiopancreatography of multifocal intraductal papillary mucinous neoplasms of the side branches: MR pattern and its evolution.

PURPOSE: This paper describes the magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) pattern of multifocal intraductal papillary mucinous tumours (IPMT) of the pancreatic side branches and its evolution during followup. MATERIALS AND METHODS: Twenty-six patients with multifocal IPMT of the side branches were included in this retrospective study. Inclusion criteria were > or =2 ectasic side branches, presence of communication with the main pancreatic duct, and > or =2 MRI/MRCP examinations after > or = 6-12 months. Exclusion criteria were IPMT involving both the main pancreatic duct and its branch ducts, previous surgery and lack of follow-up MRI examinations. Median follow-up was 27 (range 6-59) months. Images were assessed qualitatively and quantitatively. Qualitative assessment considered: the number of cystic lesions of the branch ducts, morphology of the communication between the cystic lesion and the main duct (direct or neck), presence of intraluminal filling defects within the cystic lesions, presence of mural nodules and mural enhancement of the cystic lesion. quantitative assessment considered mean maximal diameter of the cystic lesions and mean length of the communication neck. RESULTS: At diagnosis, the mean number of cystic lesions of the side branches was 7.5. a communication neck was detected in 16/26 patients (60%). Intraluminal filling defects in the side branches were present in 6/26 patients (23%). Mural nodules were seen in 1/26 patients (4%). The mean diameter of the cystic lesions was 18.8 mm. The mean length of the communication neck was 6.9 mm. At follow-up, the mean number of cystic lesions of the side branches was 8.4. A communication neck was detected in 20/26 patients (77%). Intraluminal filling defects in the side branches were detected in 7/26 patients (27%); mural nodules were seen in 2/26 patients (8%). Mural enhancement of the branch duct was detected in 2/26 patients (8%). The mean diameter of the cystic lesions increased to 22.3 mm (p < 0.05), and the mean length of the communication neck was 8.6 mm. CONCLUSIONS: MultifocaL IPMT of the side branches shows a constant but very slow progression over time. In our series, only 2/26 patients showed mural nodules.