Multicentric characterization of organ-based tube current modulation in head computed tomography: A dosimetric and image quality study.

Purpose: To evaluate the efficiency of organ-based tube current modulation (OBTCM) in head Computed Tomography (CT) for different radiology departments and manufacturers.

Materials And Methods: Five CT scanners from four radiology departments were evaluated in this study. All scans were performed using a standard and a routine head protocol.

Validation of a New Scintillating Fiber Dosimeter for Radiation Dose Quality Control in Computed Tomography.

(1) Background: The IVIscan is a commercially available scintillating fiber detector designed for quality assurance and in vivo dosimetry in computed tomography (CT). In this work, we investigated the performance of the IVIscan scintillator and associated method in a wide range of beam width from three CT manufacturers and compared it to a CT chamber designed for Computed Tomography Dose Index (CTDI) measurements. (2) Methods: We measured weighted CTDI (CTDIw) with each detector in accordance with the requirements of regulatory tests and international recommendations for the minimum, maximum and the most used beam width in clinic and investigated the accuracy of the IVIscan system based on the assessment of the CTDIw deviation from the CT chamber.

COVID-19 and vaccination impact on radiology departments provided by Dose Archiving and Communication System.

Objectives: To study the impact of COVID-19 on chest CT practice during the different waves using Dose Archiving and Communication System (DACS).

Methods: Retrospective study including data from 86,136 chest CT acquisitions from 27 radiology centers (15 private; 12 public) between January 1, 2020, and October 13, 2021, using a centralized DACS. Daily chest CT activity and dosimetry information such as dose length product (DLP), computed tomography dose index (CTDI), and acquisition parameters were collected.

Accelerated sequences of 4D flow MRI using GRAPPA and compressed sensing: A comparison against conventional MRI and computational fluid dynamics.

Purpose: To evaluate hemodynamic markers obtained by accelerated GRAPPA (R = 2, 3, 4) and compressed sensing (R = 7.6) 4D flow MRI sequences under complex flow conditions.

Methods: The accelerated 4D flow MRI scans were performed on a pulsatile flow phantom, along with a nonaccelerated fully sampled k-space acquisition.

Numerical simulation of time-resolved 3D phase-contrast magnetic resonance imaging.

A numerical approach is presented to efficiently simulate time-resolved 3D phase-contrast Magnetic resonance Imaging (or 4D Flow MRI) acquisitions under realistic flow conditions. The Navier-Stokes and Bloch equations are simultaneously solved with an Eulerian-Lagrangian formalism. A semi-analytic solution for the Bloch equations as well as a periodic particle seeding strategy are developed to reduce the computational cost.

Impact of Thoracic Endografting on the Hemodynamics of the Native Aorta: Pre- and Postoperative Assessments of Wall Shear Stress and Vorticity Using Computational Fluid Dynamics.

Purpose: To quantify the hemodynamic consequences of thoracic endovascular aortic repair (TEVAR) by comparing the preoperative and postoperative wall shear stress (WSS) and vorticity profiles on computational fluid dynamics (CFD) simulations.

Materials And Methods: The pre- and postoperative computed tomography (CT) scans from 20 consecutive patients (median age 69 years, range 20-87) treated for different thoracic aortic pathologies (11 aneurysms, 5 false aneurysms, 3 penetrating ulcers, and 1 traumatic aortic rupture) were segmented to construct patient-specific CFD models using a meshless code. The simulations were run over the cardiac cycle, and the WSS and vorticity values measured at the proximal and distal landing zones were compared.

Combining Volumetric and Wall Shear Stress Analysis from CT to Assess Risk of Abdominal Aortic Aneurysm Progression.

Background Despite known limitations, the decision to operate on abdominal aortic aneurysm (AAA) is primarily on the basis of measurement of maximal aneurysm diameter. Purpose To identify volumetric and computational fluid dynamics parameters to predict AAAs that are likely to progress in size. Materials and Methods This study, part of a multicenter prospective registry (NCT01599533), included 126 patients with AAA.

Reconciling PC-MRI and CFD: An in-vitro study.

Several well-resolved 4D Flow MRI acquisitions of an idealized rigid flow phantom featuring an aneurysm, a curved channel as well as a bifurcation were performed under pulsatile regime. The resulting hemodynamics were processed to remove MRI artifacts. Subsequently, they were compared with CFD predictions computed on the same flow domain, using an in-house high-order low dissipative flow solver.

Low-dose biplanar radiography can be used in children and adolescents to accurately assess femoral and tibial torsion and greatly reduce irradiation.

Purpose: To evaluate in children the agreement between femoral and tibial torsion measurements obtained with low-dose biplanar radiography (LDBR) and CT, and to study dose reduction ratio between these two techniques both in vitro and in vivo.

Materials And Methods: Thirty children with lower limb torsion abnormalities were included in a prospective study. Biplanar radiographs and CTs were performed for measurements of lower limb torsion on each patient.

Impact of endografting on the thoracic aortic anatomy: comparative analysis of the aortic geometry before and after the endograft implantation.

Purpose: Although the widespread acceptance of thoracic endovascular aortic repair (TEVAR) as a first-line treatment option for a multitude of thoracic aortic diseases, little is known about the consequences of the device implantation on the native aortic anatomy. We propose a comparative analysis of the pre- and postoperative geometry on a clinical series of patients and discuss the potential clinical implications

Methods: CT pre- and postoperative acquisitions of 30 consecutive patients treated by TEVAR for different pathologies (20 thoracic aortic aneurysms, 6 false aneurysms, 3 penetrating ulcers, 1 traumatic rupture) were used to model the vascular geometry. Pre- and postoperative geometries were compared for each patient by pairing and matching the 3D models.

Haemodynamic imaging of thoracic stent-grafts by computational fluid dynamics (CFD): presentation of a patient-specific method combining magnetic resonance imaging and numerical simulations.

Objectives: In the last decade, there was been increasing interest in finding imaging techniques able to provide a functional vascular imaging of the thoracic aorta. The purpose of this paper is to present an imaging method combining magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) to obtain a patient-specific haemodynamic analysis of patients treated by thoracic endovascular aortic repair (TEVAR).

Methods: MRI was used to obtain boundary conditions.

The role of stent-grafts in the management of aortic trauma.

Stent graft has resulted in major advances in the treatment of trauma patients with blunt traumatic aortic injury (TAI) and has become the preferred method of treatment at many trauma centers. In this review, we provide an overview of the place of stent grafts for the management of this disease. As a whole, TEVAR repair of TAIs offers a survival advantage and reduction in major morbidity, including paraplegia, compared with open surgery.

Implementation and evaluation of a national external quality control program for cervical cytology in Mexico.

Objective: To evaluate cytology laboratories and the performance of cytotechnologists for establishing efficient external quality control for Mexico's National Program for the Prevention and Control of Cervical Cancer.

Material And Methods: During January and February 1998, an onsite evaluation of all cytology laboratories of the Ministry of Health found that only 70% of the microscopes were in adequate working conditions, reagents were out of date, and working conditions were sub-optimal. A program for external quality control based on proficiency testing was established for cytotechnologists.