BackgroundThe first aim of this study was to evaluate the correlation between clinical and physical-technical image quality applied to different strengths of iterative reconstruction in chest CT images using Thiel cadaver acquisitions and Catphan images. The second aim was to determine the potential dose reduction of iterative reconstruction compared to conventional filtered back projection based on different clinical and physical-technical image quality parameters.MethodsClinical image quality was assessed using three Thiel embalmed human cadavers. A Catphan phantom was used to assess physical-technical image quality parameters such as noise, contrast-detail and contrast-to-noise ratio (CNR).Both Catphan and chest Thiel CT images were acquired on a multislice CT scanner at 120 kVp and 0.9 pitch. Six different refmAs settings were applied (12, 30, 60, 90, 120 and 150refmAs) and each scan was reconstructed using filtered back projection (FBP) and iterative reconstruction (SAFIRE) algorithms (1,3 and 5 strengths) using a sharp kernel, resulting in 24 image series. Four radiologists assessed the clinical image quality, using a visual grading analysis (VGA) technique based on the European Quality Criteria for Chest CT.ResultsCorrelation coefficients between clinical and physical-technical image quality varied from 0.88 to 0.92, depending on the selected physical-technical parameter. Depending on the strength of SAFIRE, the potential dose reduction based on noise, CNR and the inverse image quality figure (IQFinv) varied from 14.0 to 67.8 %, 16.0 to 71.5 % and 22.7 to 50.6 % respectively. Potential dose reduction based on clinical image quality varied from 27 to 37.4 %, depending on the strength of SAFIRE.ConclusionOur results demonstrate that noise assessments in a uniform phantom overestimate the potential dose reduction for the SAFIRE IR algorithm. Since the IQFinv based dose reduction is quite consistent with the clinical based dose reduction, an optimised contrast-detail phantom could improve the use of contrast-detail analysis for image quality assessment in chest CT imaging. In conclusion, one should be cautious to evaluate the performance of CT equipment taking into account only physical-technical parameters as noise and CNR, as this might give an incomplete representation of the actual clinical image quality performance.

Introduction Image-guided biopsy is an important tool in the diagnosis of solid pancreatic masses. This study aims to evaluate the accuracy and complications associated with this procedure. Methods We conducted a retrospective cohort study of all patients referred to interventional radiology for pancreatic biopsy at our institution from July 2004-July 2015. Two radiologists independently reviewed the images, technical aspects, and clinical characteristics. Results A total of 82 patients underwent pancreatic biopsy using a combination of computed tomography (CT) and/or ultrasound guidance. Mean age was 67.8 years with 56% males. Most lesions were located in the head (63.4%), followed by the tail (19.5%), and the body (17.1%). The procedures were performed using the anterior (79.3%), lateral (7.3%), or posterior (13.4%) approach, with direct access in 85.4% of the patients and indirect access (transgastric or transhepatic) in 14.6% of cases. Core biopsies were obtained in 81.7% of cases, and fine needle aspiration was performed in 18.3% of cases. Needle size varied from 18–22 gauge (median 20 gauge). The median number of samples collected was 3 (range 1–8). A conclusive result was obtained in 82.9% of cases. There were 9 (11%) patients with minor complications: minor bleeding, pain, and inadvertent bowel puncture with no clinical repercussion. There were no deaths or major complications. Conclusion Percutaneous image-guided pancreatic mass biopsy can be performed safely with excellent accuracy. Our results are comparable with endoscopic biopsy/aspiration, and percutaneous biopsy may be used as an alternative, particularly at institutions where endoscopy facilities are limited.

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