Comparison of radiation exposure from dual- and single-energy CT imaging protocols resulting in equivalent contrast-to-noise ratio of lesions for adults and children: a phantom study.

Objectives: To compare the radiation exposure from single-energy CT (SECT) against rapid kV-switching dual-energy CT (DECT) imaging in both adults and children when resulting image data offer equivalent lesion identification power.

Materials And Methods: Lesions in an adult and a 10-year-old-child body phantom were imitated using iodine solutions of different concentrations. Phantoms were subjected to several SECT and DECT thoracic and abdominal scans using a rapid kV-switching DECT scanner.

Is deep learning-enabled real-time personalized CT dosimetry feasible using only patient images as input?

Purpose: To propose a novel deep-learning based dosimetry method that allows quick and accurate estimation of organ doses for individual patients, using only their computed tomography (CT) images as input.

Methods: Despite recent advances in medical dosimetry, personalized CT dosimetry remains a labour-intensive process. Current state-of-the-art methods utilize time-consuming Monte Carlo (MC) based simulations for individual organ dose estimation in CT.

Dual-Energy Computed Tomography as an Adjunct in the Evaluation of Peripheral Chronic Total Occlusions: A Feasibility Study.

This study investigated the role of dual-energy computed tomography (CT) for lesion characterization in patients with peripheral arterial disease manifesting with chronic total occlusions (CTOs). Forty-one symptomatic patients with CTOs underwent dual-energy CT angiography before endovascular treatment. The lesions were subsequently analyzed in a dedicated workstation, and 2 indexes-dual-energy index (DEI) and effective Z (Z)-were calculated, ranging from 0.

Individualized dosimetry in Ru-106 ophthalmic brachytherapy based on MRI-derived ocular anatomical parameters.

Purpose: To estimate ocular geometry-related inaccuracies of the dosimetric plan in Ru-106 ophthalmic brachytherapy.

Methods And Materials: Thirty patients with intraocular lesions were treated with brachytherapy using a Ru-106 plaque-shell of inner radius of 12 mm. Magnetic resonance imaging was employed to determine the external scleral radius at tumor site and the tumor margins.

Dual-energy CT angiography in imaging surveillance of endovascular aneurysm repair - Preliminary study results.

Purpose: To investigate the value of dual-energy CT imaging to discriminate low- from high- risk type II endoleaks (T2EL) after endovascular aneurysm repair (EVAR).

Method: Study participants were consecutive patients referred for CT at 1-month post-EVAR. CT imaging acquisition included a dual-energy CT angiography (DECTA) and a delayed single-energy CT (SECT) imaging.

Radiomics and machine learning to predict aggressive type 2 endoleaks after endovascular aneurysm repair: a proof of concept.

Background: Persistent type 2 endoleaks (T2EL) require lifelong surveillance to avoid potentially life-threatening complications.

Purpose: To evaluate the performance of radiomic features (RF) derived from computed tomography angiography (CTA), for differentiating aggressive from benign T2ELs after endovascular aneurysm repair (EVAR).

Material And Methods: A prospective study was performed on patients who underwent EVAR from January 2018 to January 2020.

Cerebral CT Perfusion in Acute Stroke: The Effect of Lowering the Tube Load and Sampling Rate on the Reproducibility of Parametric Maps.

The aim of this study was to define lower dose parameters (tube load and temporal sampling) for CT perfusion that still preserve the diagnostic efficiency of the derived parametric maps. Ninety stroke CT examinations from four clinical sites with 1 s temporal sampling and a range of tube loads (mAs) (100-180) were studied. Realistic CT noise was retrospectively added to simulate a CT perfusion protocol, with a maximum reduction of 40% tube load (mAs) combined with increased sampling intervals (up to 3 s).

Radiation exposure to infants undergoing voiding cystourethrography: The importance of the digital imaging technology.

Purpose: To determine the radiation burden to infants undergoing voiding cystourethrography (VCUG) in a single institution and investigate the effect of shifting from analogue to digital imaging that allowed the use of a radiography-free examination protocol.

Methods: Anthropometric and exposure data were prospectively collected for 35 consecutive infants undergoing VCUG on a digital system with a standardized examination protocol not including radiographs. Thermoluminescent dosimeters were used to determine entrance-skin dose.

MRI and dual-energy CT fusion anatomic imaging in Ru-106 ophthalmic brachytherapy.

Purpose: Brachytherapy with Ru-106 is widely used for the treatment of intraocular tumors, and its efficacy depends on the accuracy of radioactive plaque placement. Ru-106 plaques are MRI incompatible and create severe metal artifacts on conventional CT scans. Dual-energy CT scans (DECT) may be used to suppress such artifacts.

Discrimination of High-Risk Type-2 Endoleak after Endovascular Aneurysm Repair through CT Perfusion: A Feasibility Study.

A type-2 endoleak after an endovascular aneurysm repair is the most prevalent type of endoleak, but as the clinical consequence of its diagnosis is uncertain, at present, management decisions are solely based on aneurysm sac growth. The aim of this study was to investigate the potential of various computed tomography perfusion parameters for their ability to distinguish high-risk type-2 endoleaks from low-risk type-2 endoleaks after an endovascular aneurysm repair.

A novel personalized dosimetry method for endovascular aneurysm repair (EVAR) procedures.

Objective: To estimate radiation doses for the primarily irradiated organs/tissues of patients subjected to standard endovascular aneurysm repair (EVAR) procedures using a novel personalized dosimetry method.

Methods: Dosimetric and anthropometric data were collected prospectively for eight patients who underwent standard EVAR procedures. Patient-specific Monte Carlo simulations were performed to estimate organ/tissue doses from each of the fluoroscopic and digital subtraction angiography acquisitions involved in EVAR.

CT liver perfusion in patients with hepatocellular carcinoma: can we modify acquisition protocol to reduce patient exposure?

Objectives: To investigate the potential of decreasing the number of scans and associated radiation exposure involved in CT liver perfusion (CTLP) dynamic studies for hepatocellular carcinoma (HCC) assessment.

Methods: Twenty-four CTLP image datasets of patients with HCC were retrospectively analyzed. All examinations were performed on a modern CT system using a standard acquisition protocol involving 35 scans with 1.

Effect of scan projection radiography coverage on tube current modulation in pediatric and adult chest CT.

Purpose: To investigate the effect of scan projection radiography (SPR) coverage on tube current modulation in pediatric and adult thoracic CT examinations.

Methods: Sixty pediatric and 60 adult chest CT examinations were retrospectively studied to determine the incidence rate of examinations involving SPRs that did not include the entire image volume (IV) or the entire primarily exposed body volume (PEBV). The routine chest CT acquisition procedure on a modern 64-slice CT system was imitated on five anthropomorphic phantoms of different size.

CT coronary angiography in asymptomatic male patients with high atherosclerosis risk: Is it justified?

Purpose: To study the necessity of coronary artery screening with computerized tomography coronary angiography (CTCA) in asymptomatic male patients.

Material And Methods: A total of 226 asymptomatic male patients aged over 50 years were included in this prospective study, according to a clinical protocol approved by the Heraklion University Hospital's Ethics Committee. All participants had at least 3 or more known atherosclerosis risk factors.

Dual-energy CT imaging of orbits during episcleral brachytherapy with Ru-106 plaques: A phantom study on its potential for plaque position verification.

Purpose: To investigate the potential of dual energy CT (DECT) to suppress metal artifacts and accurately depict episcleral brachytherapy Ru-106 plaques after surgical placement.

Methods: An anthropomorphic phantom simulating the adult head after surgical placement of a Ru-106 plaque was employed. Nine DECT acquisition protocols for orbital imaging were applied.

Dynamic CT perfusion imaging for type 2 endoleak assessment after endograft placement.

Endovascular repair of abdominal aortic aneurysm is a widely performed treatment method due to its minimal invasiveness, reduced need for intensive care unit (ICU), shorter hospitalization and lower 30-day morbidity and mortality compared to open surgery. Endoleak is the drawback of this procedure and is considered the main culprit for re-interventions due to the risk of late aneurysm sac growth and rupture. Type 2 endoleak (T2EL) is the most common type of endoleak which is also the most controversial regarding its management.

The effect of heart rate, vessel angulation and acquisition protocol on the estimation accuracy of calcified artery stenosis in dual energy cardiac CT: A phantom study.

Purpose: To investigate the effects of heart beat rate (bpm), vessel angulation and acquisition protocol on the estimation accuracy of calcified stenosis using a dual-energy CT scanner.

Methods: A thorax semi-anthropomorphic phantom coupled with a motion simulator and a vessel phantom representing a 50% coronary artery calcified stenosis, were used. Electrocardiograph (ECG)-synchronized acquisitions were performed at different bpms.

PET/CT and PET/MRI in ophthalmic oncology (Review).

Orbital and ocular anatomy is quite complex, consisting of several tissues, which can give rise to both benign and malignant tumors, while several primary neoplasms can metastasize to the orbital and ocular space. Early detection, accurate staging and re‑staging, efficient monitoring of treatment response, non‑invasive differentiation between benign and malignant lesions, and accurate planning of external radiation treatment, are of utmost importance for the optimal and individualized management of ophthalmic oncology patients. Addressing these challenges requires the employment of several diagnostic imaging techniques, such as high‑definition digital fundus photography, ultrasound imaging, optical coherence tomography, optical coherence tomography (OCT)‑angiography, computed tomography (CT) and magnetic resonance imaging (MRI).

Are obesity indices derived by dual-energy x-ray absorptiometry capable of identifying postmenopausal females with high risk for coronary heart disease?

Objective: The aim of the study was to evaluate the predictive ability of obesity indices derived by dual-energy x-ray absorptiometry (DXA) regarding coronary heart disease (CHD).

Methods: DXA total body scans were performed on 71 consecutive postmenopausal women who were referred for myocardial perfusion imaging (MPI). Twenty-four women with CHD diagnosed by MPI were considered as cases, whereas the remaining 47 women with normal MPI results were considered as controls.

CT Foot Perfusion Examination for Evaluation of Percutaneous Transluminal Angioplasty Outcome in Patients with Critical Limb Ischemia: A Feasibility Study.

Purpose: To evaluate foot perfusion in patients with critical limb ischemia (CLI) using quantitative perfusion multi-detector-row CT and estimate perfusion parameter changes before and after percutaneous transluminal angioplasty (PTA).

Materials And Methods: This prospective study investigated 13 patients (10 men; median age, 72 y; range, 51-84 y) with CLI who underwent CT foot perfusion examinations with a 128-slice dual-energy CT scanner 1 day before and 1 week after PTA. Key parameters such as permeability surface (PS), blood volume (BV), and blood flow (BF) were analyzed and compared statistically.

Comparison of patient dose from routine multi-phase and dynamic liver perfusion CT studies taking into account the effect of iodinated contrast administration.

Objectives: To accurately determine and compare patient radiation burden from routine multi-phase CT (MPCT) and dynamic CT liver perfusion (CTLP) studies taking into account the effect of iodine uptake of exposed tissues/organs.

Materials And Methods: 40 consecutive MPCT of upper abdomen and 40 consecutive CTLP studies performed on a modern CT scanner were retrospectively studied. Iodine uptake of radiosensitive tissues at the time of acquisition was calculated through the difference of tissues' CT numbers between NECT and CECT images.

Does lung perfusion scintigraphy continue to have a role in the clinical management of patients suspected of pulmonary embolism in the CT pulmonary angiography era?

Objective: Acute pulmonary embolism (PE) is a life-threatening disorder with high mortality. A prompt diagnosis and treatment is essential for reducing the mortality rate. The purpose of the study is to evaluate if lung perfusion scintigraphy (LPS) continues to have a role in the clinical management of patients suspected of pulmonary embolism in the CT pulmonary angiography (CTPA) era.

A correlative study between diffusion and perfusion MR imaging parameters on peripheral arterial disease data.

Purpose: The purpose of this study was to correlate diffusion and perfusion quantitative and semi-quantitative MR parameters, on patients with peripheral arterial disease. In addition, we investigated which perfusion model better describes the behavior of the dynamic contrast-enhanced (DCE) MR data signal on ischemic regions of the lower limb.

Methods: Linear and nonlinear least squares algorithms, were incorporated for the quantification of the parameters through a variety of widely used models, able to extract physiological information from each imaging technique.

Perfusion-CT analysis for assessment of hepatocellular carcinoma lesions: diagnostic value of different perfusion maps.

Background: Computed tomography liver perfusion (CTLP) has been improved in recent years, offering a variety of perfusion-parametric maps. A map that better discriminates hepatocellular carcinoma (HCC) is still to be found.

Purpose: To compare different CTLP maps, regarding their ability to differentiate cirrhotic or non-cirrhotic parenchyma from malignant HCC.

What is the underestimation of radiation dose to the pediatric thyroid gland from contrast enhanced CT, if contrast medium uptake is not taken into account?

Purpose: To assess the underestimation of radiation dose to the thyroid of children undergoing contrast enhanced CT if contrast medium uptake is not taken into account.

Methods: 161 pediatric head, head & neck and chest CT examinations were retrospectively studied to identify those involving pre- and post-contrast imaging and thyroid inclusion in imaged volume. CT density of thyroid tissue in HU was measured in non-enhanced (NECT) and corresponding contrast-enhanced CT (CECT) images.