Pancreatic cancer detection with a non-contrast MR protocol: is it reliable?

PURPOSE: The pancreatic cancer (PC) is the 4th leading cancer-related death, becoming the second one by 2030, with a 5 year survival rate of 8%. Considering its increased incidence in high-risk categories compared to the general population, we aimed to validate a non-contrast MR protocol, to detect PC in its earliest phase, which could be suitable as a screening tool in high-risk patients. MATERIALS AND METHODS: In this retrospective study, we selected 200 patients (> 40 years) from our radiological database, which performed upper abdominal MRI between 2012 and 2017. 100 were negative for pancreatic lesions and 100 positive for pancreatic lesion (< 30 mm). The latter group included: 40 PDAC (pancreatic adenocarcinoma), 42 BD-IPMN (Branch Duct- Intraductal Papillary Mucinous Neoplasm), 10 PNET(pancreatic neuroendocrine tumor), 4 SCN(serous cystic neoplasm), 3 IPS(intrapancreatic spleen), 1 MCN(mucinous cystic neoplasm). Three readers (R1, R2 and R3) with a high, medium and low experience, respectively, analysed, first, the non-contrast MR sequences (single-shot T2w breath-hold, GE T1w FS, DWI and 2D/3D MRCP), and then the standard MR protocol, independently, randomly and anonymously. Readers identified or excluded the presence of pancreatic lesion, in both reading sessions. These results were compared with the histopathological diagnosis, and then divided into 3 different classes of lesions: all lesions, pancreatic adenocarcinoma and solid lesion. Mcnemar's test was used to compare the results. The inter-observer agreement was determined according to the kappa statistic in both protocols, and then the inter-protocol agreement was calculated. RESULTS: The non-contrast MR protocol has reached statistical parameters values ranging between 83% in SE (sensitivity) by R3 and 99% in NPV (negative predictive value) by R1. The standard MR protocol has reported slight increasing statistical parameters compared to those of the proposed one. However, there are not significant statistical differences between the both protocols. The proposed non-contrast MR protocol has reported the highest NPVs in the PDAC group detection (R1: 99%, R2: 99%, R3: 98%). In all groups of lesions, the agreement between the two protocols was excellent for each Reader ranging from 96 to 98%. CONCLUSION: The proposed non-contrast MR protocol showed high PC detection values and a time execution ≤ 20 min. Therefore, it can be proposed as a screening tool in high-risk patients.

An intriguing intracardiac mass in a woman with atrial fibrillation. Left atrial appendage (LAA) thrombus.

CLINICAL INTRODUCTION: A 74-year-old hypertensive woman presented with shortness of breath. There was no associated coughing, chest pain or fever. ECG identified atrial fibrillation with rapid ventricular response. A transoesophageal echocardiogram was scheduled to exclude thrombus before cardioversion (Figure 1A); however, an echogenic structure was seen (Figure 1B arrow, see online supplementary video 1) between the left atrium, the pulmonary artery and the aortic root. QUESTION: Which of the following is the most likely diagnosis? A. Aortic valve endocarditis with annular abscess. B. Left atrial appendage thrombus. C. Left atrial myxoma. D. Pulmonary embolism.

Use of contrast agents in oncological imaging: magnetic resonance imaging.

Magnetic resonance plays a leading role in the management of oncology patients, providing superior contrast resolution and greater sensitivity compared with other techniques, which enables more accurate tumor identification, characterization and staging. Contrast agents are widely used in clinical magnetic resonance imaging; approximately 40-50% of clinical scans are contrast enhanced. Most contrast agents are based on the paramagnetic gadolinium ion Gd3+, which is chelated to avoid the toxic effects of free gadolinium. Multiple factors such as molecule structure, molecule concentration, dose, field strength and temperature determine the longitudinal and transverse relaxation rates (R1 and R2, respectively) and thus the T1- and T2-relaxivities of these chelates. These T1- and T2-relaxivities, together with their pharmacokinetic properties (i.e. distribution and concentration in the area of interest), determine the radiologic efficacy of the gadolinium-based contrast agents.

Imaging for oncologic staging and follow-up: review of current methods and novel approaches.

PURPOSE: To review the current radiological methodologies and guidelines for staging and followup in oncology, and to give a perspective based on the available new technologies in oncologic radiology. MATERIALS AND METHODS: The literature on cancer radiologic quantification in diagnostic phase and follow-up has been reviewed. The main concepts and guidelines (official and non-official) have been extracted taking into account the period of publication and the available technology. The current World Health Organization (WHO) and Response Evaluation Criteria In Solid Tumors (RECIST) guidelines have been critically evaluated on the basis of technical literature on quantitative radiology applied to oncology. Pitfalls of previous and current guidelines have been exploited on the basis of currently available techniques for quantification. RESULTS: Errors due to operator, scanner, software, and measurement technique inconsistency are all together far more relevant than the recognized thresholds applied for detecting therapeutic response. For this reason the volumetric assessment of cancer disease should be introduced. CONCLUSION: Even though the technical constraints are still prominent in the clinical practice, the design of clinical trials should be planned taking into account these new volumetric quantitative techniques.