S. Mazzocchi

Quality assurance multicenter comparison of different MR scanners for quantitative diffusion-weighted imaging

To propose a magnetic resonance imaging (MRI) quality assurance procedure that can be used for multicenter comparison of different MR scanners for quantitative diffusion‐weighted imaging (DWI).

A study of feasibility of dose reduction in paediatric MSCT scanning with a constant image quality.

The aim of the work relies on the adjustment of scanning parameters, kV and mAs, in multislice computed tomography (MSCT) to reduce paediatric patient dose whilst keeping the same reference image quality. Only abdomen examinations are employed in this study. The measurement of noise in a region of interest (ROI) inside the liver in a reference adult man has been chosen as an image quality parameter. Paediatric patients are categorised according to the width and thickness of abdomen trunk. A relationship between patient size, image quality and dose reduction has been obtained. The study has been performed at the Meyer Children Hospital (1300 CT paediatric patient/year).

A comparison study of radiation exposure to patients during EVAR and Dyna CT in an angiosuite vs. an operating theatre

The aim of this study was to assess the patient dosimetric impact of endovascular abdominal aortic aneurysm repair (EVAR), both in an operating theatre (OR) and in an angiosuite (AS), with the facility of Dynamic CT (Dyna CT, Siemens AG, Berlin, Germany). One hundred and forty-six consecutive EVAR procedures dating from May 2011 to March 2013 were analysed. These were performed either in an OR (n = 97) using a mobile C-arm or in an AS (n = 49) equipped with a ceiling-mounted angiography system. Air kerma area product (P(KA)) and total air kerma at reference point (K(a,r)) values were reported for all procedures and Dyna CT. Radiation exposure during EVAR was quite low in the majority of patients but nearly 50 % higher if performed in AS vs. OR. Median Dyna CT K(a,r) was the same as an entire EVAR procedure in OR. The higher patients radiation exposure recorded in the AS should be balanced with the technical advantages given to the EVAR procedure.

Dependence of apparent diffusion coefficient measurement on diffusion gradient direction and spatial position – A quality assurance intercomparison study of forty-four scanners for quantitative diffusion-weighted imaging

PURPOSE To propose an MRI quality assurance procedure that can be used for routine controls and multi-centre comparison of different MR-scanners for quantitative diffusion-weighted imaging (DWI). MATERIALS AND METHODS 44 MR-scanners with different field strengths (1 T, 1.5 T and 3 T) were included in the study. DWI acquisitions (b-value range 0-1000 s/mm2), with three different orthogonal diffusion gradient directions, were performed for each MR-scanner. All DWI acquisitions were performed by using a standard spherical plastic doped water phantom. Phantom solution ADC value and its dependence with temperature was measured using a DOSY sequence on a 600 MHz NMR spectrometer. Apparent diffusion coefficient (ADC) along each diffusion gradient direction and mean ADC were estimated, both at magnet isocentre and in six different position 50 mm away from isocentre, along positive and negative AP, RL and HF directions. RESULTS A good agreement was found between the nominal and measured mean ADC at isocentre: more than 90% of mean ADC measurements were within 5% from the nominal value, and the highest deviation was 11.3%. Away from isocentre, the effect of the diffusion gradient direction on ADC estimation was larger than 5% in 47% of included scanners and a spatial non uniformity larger than 5% was reported in 13% of centres. CONCLUSION ADC accuracy and spatial uniformity can vary appreciably depending on MR scanner model, sequence implementation (i.e. gradient diffusion direction) and hardware characteristics. The DWI quality assurance protocol proposed in this study can be employed in order to assess the accuracy and spatial uniformity of estimated ADC values, in single- as well as multi-centre studies.

IP007. Feasibility of Endovascular Abdominal Aortic Aneurysm Repair Procedure Supported by Very-Low-Dose Stationary Acquisition Protocols∗

population. AD mortality trends were evaluated within sex and race strata and compared with aortic aneurysm mortality using linear regression. Differences in county-specific mortality rates were assessed using the Kruskal-Wallis test. Results: Of the 1,014,039 total deaths that occurred during the study period, 2048 were AD related (60% male, 88% white). In 82% of the cases, AD was noted as the underlying COD (Table). The mean AD-related mortality rate was 1.7 6 0.3 deaths/100,000 compared with 6.3 6 1.7 deaths/ 100,000, the aortic aneurysm-related mortality. There was no change in AD-related mortality over time in comparison to a decline in aortic aneurysm-related mortality during the same period (P < .001; Fig). In ADrelated deaths, the mean age at death was 67.8 6 16.0 years and remained stable over time. Whereas there were no differences in ADrelated mortality rates by sex (P 1⁄4 .9), there was a significant increase in mortality rate among individuals who are nonwhite compared with white (an increase of 0.04 vs 0.0006 death/100,000/year, respectively; P 1⁄4 .01). Mortality rates varied significantly across counties (range, 0.02145.9 deaths/100,000; P < .001), and there was no obvious pattern to this variation. An autopsy was completed in 640 (32%) cases, of which 92% reported AD as underlying COD. Among those, 50.2% had an associated COD of aortic rupture. A higher percentage of hypertensive heart disease was noted among those with rupture (70% vs 47%; P < .001). Conclusions: AD-related mortality did not decline in 21 years in Washington state in contrast to a significant drop in aortic aneurysm-related mortality during the same period. Significant racial and geographic variations were noted. These observations are a first step toward regional population assessments that could potentially change care patterns at the state level.

Multi hospital experiences in the use of RDIM softwares to optimize radiological procedures in computed tomography, mammography and interventional radiology

Introduction Radiation Dose Index Monitoring (RDIM) are useful software tools that allow radiological data collection and patient dose monitoring. However its implementation need a thorough acceptance test. Purpose Aim of this work is to test the consistency of data processed by two RDIM software and use the dose index information archived to optimize radiological procedures in our hospitals. Materials and methods We began in 2012 to monitor dose index data from 7 CTs and 2 angiographic units using CareAnalytics (CA) tool by Siemens. CA processes DICOM RDSR stored in PACS. Moreover within an Italian project, RDM by Medsquare has been tested since Gen 2015. RDM collects and analyzes doses delivered to patients during medical imaging examinations. One mammographic installation, 2 CTs and 1 angiographic unit has been connected to RDM. Results For angiographic procedure we have compared the maximum incident air kerma at the reference point at different times and at different C arm positions with the dose values obtained by softwares. For mammography, data from header DICOM have been positively compared with RDM data. For CT we have compared values obtained from console, CA and RDM. Conclusion In our experiences both the software under test seems to be useful tools to monitor radiation dose index. RDM allows wider applications and custom made options. Disclosure Nothing to declare.