Scout Images Research Articles

Development of the Sphenoid Sinus in Japanese Children: A Retrospective Longitudinal Study Using Three-Dimensional Computed Tomography.

The sphenoid sinus (SS) is located close to vital structures, such as the pituitary gland, and it has significant clinical relevance. This study aimed to clarify the growth pattern of the SS in Japanese children using three-dimensional computed tomography (CT). Seventy-eight participants with congenital, acquired, or external auditory canal cholesteatoma were recruited and underwent CT more than twice during their treatment. Using the volume-rendered images, the size and volume of the SS were measured. Furthermore, on the scout image, the morphological measurements of the cranial base were determined. The size and volume of the SS increased with age, and peaked at the mean age of 15 years. For males, the volume of the SS was smaller than that of females aged <5 years. The growth rate of the SS was significantly higher in males than in females. The maximum growth rate was detected at the age of 12 years for males and 10 years for females. For females, the increase in the length of the anterior cranial base ceased at approximately 10 years of age and remained constant thereafter. In contrast, for males, the length of the anterior cranial base increased gradually until 15 years of age. Considering the similarity of the periods between the adolescent growth spurt and the maximum growth rate of the SS, changes in the size of the SS may be used as an indicator of the physical growth spurt.

Cardiac magnetic resonance imaging in patients with left bundle branch block: Patterns of dyssynchrony and implications for late gadolinium enhancement imaging.

Left bundle branch block (LBBB) is a ventricular conduction delay with high prevalence. Aim of our study is to identify possible recurring patterns of artefacts in late gadolinium enhancement (LGE) imaging in patients with LBBB who undergo cardiac magnetic resonance imaging (MRI) and to define parameters of mechanical dyssynchrony associated with artefacts in LGE images. Fifty-five patients with LBBB and 62 controls were retrospectively included. Inversion time (TI) scout and LGE images were reviewed for artefacts. Dyssynchrony was identified using cardiac MRI by determining left ventricular systolic dyssynchrony indices (global, septal segments, and free wall segments) derived from strain analysis and features of mechanical dyssynchrony (apical rocking and septal flash). Thirty-seven patients (67%) with LBBB exhibited inhomogeneous myocardial nulling in TI scout images. Among them 25 (68%) patients also showed recurring artefact patterns in the septum or free wall on LGE images and artefacts also persisted in 18 (72%) of those cases when utilising phase sensitive inversion recovery. Only the systolic dyssynchrony index of septal segments allowed differentiation of patient subgroups (artefact/no artefact) and healthy controls (given as median, median ± interquartile range); LBBB with artefact: 10.44% (0.44-20.44%); LBBB without artefact: 6.82% (-2.18-15.83%); controls: 4.38% (1.38-7.38%); p < 0.05 with an area under the curve of 0.863 (81% sensitivity, 89% specificity). Septal flash and apical rocking were more frequent in the LBBB with artefact group than in the LBBB without artefact group (70 and 62% versus 33 and 17%; p < 0.05). Patients with LBBB show recurring artefact patterns in LGE imaging. Use of strain analysis and evaluation of mechanical dyssynchrony may predict the occurrence of such artefacts already during the examination and counteract misinterpretation.

Biological fingerprint for patient verification using trunk scout views at various scan ranges in computed tomography.

Immediate verification of whether a patient being examined is correct is desirable, even if the scan ranges change during different examinations for the same patient. This study proposes an advanced biological fingerprint technique for the rapid and reliable verification of various scan ranges in computed tomography (CT) scans of the torso of the same patient. The method comprises the following steps: geometric correction of different scans, local feature extraction, mismatch elimination, and similarity evaluation. The geometric magnification correction was aligned at the scanner table height in the first two steps, and the local maxima were calculated as the local features. In the third step, local features from the follow-up scout image are matched to those in the corresponding baseline scout image via template matching and outlier elimination via a robust estimator. We evaluated the correspondence rate based on the inlier ratio between corresponding scout images. The ratio of inliers between the baseline and follow-up scout images was assessed as the similarity score. The clinical dataset, including chest, abdomen-pelvis, and chest-abdomen-pelvis scans, included 600 patients (372 men, 68 ± 12years) who underwent two routine torso CT examinations. The highest area under the receiver operating characteristic curve (AUC) was 0.996, which was sufficient for patient verification. Moreover, the verification results were comparable to the conventional method, which uses scout images in the same scan range. Patient identity verification was achieved before the main scan, even in follow-up torso CT, under different scan ranges.

LRR-CED: low-resolution reconstruction-aware convolutional encoder–decoder network for direct sparse-view CT image reconstruction

Objective. Sparse-view computed tomography (CT) reconstruction has been at the forefront of research in medical imaging. Reducing the total x-ray radiation dose to the patient while preserving the reconstruction accuracy is a big challenge. The sparse-view approach is based on reducing the number of rotation angles, which leads to poor quality reconstructed images as it introduces several artifacts. These artifacts are more clearly visible in traditional reconstruction methods like the filtered-backprojection (FBP) algorithm. Approach. Over the years, several model-based iterative and more recently deep learning-based methods have been proposed to improve sparse-view CT reconstruction. Many deep learning-based methods improve FBP-reconstructed images as a post-processing step. In this work, we propose a direct deep learning-based reconstruction that exploits the information from low-dimensional scout images, to learn the projection-to-image mapping. This is done by concatenating FBP scout images at multiple resolutions in the decoder part of a convolutional encoder–decoder (CED). Main results. This approach is investigated on two different networks, based on Dense Blocks and U-Net to show that a direct mapping can be learned from a sinogram to an image. The results are compared to two post-processing deep learning methods (FBP-ConvNet and DD-Net) and an iterative method that uses a total variation (TV) regularization. Significance. This work presents a novel method that uses information from both sinogram and low-resolution scout images for sparse-view CT image reconstruction. We also generalize this idea by demonstrating results with two different neural networks. This work is in the direction of exploring deep learning across the various stages of the image reconstruction pipeline involving data correction, domain transfer and image improvement.

Comparison of automatic liver volumetry performance using different types of magnetic resonance images

Measurements of liver volume from MR images can be valuable for both clinical and research applications. Automated methods using convolutional neural networks have been used successfully for this using a variety of different MR image types as input. In this work, we sought to determine which types of magnetic resonance images give the best performance when used to train convolutional neural networks for liver segmentation and volumetry.Abdominal MRI scans were performed at 3 Tesla on 42 adolescents with obesity. Scans included Dixon imaging (giving water, fat, and T2* images) and low-resolution T2-weighted scout images. Multiple convolutional neural network models using a 3D U-Net architecture were trained with different input images. Whole-liver manual segmentations were used for reference. Segmentation performance was measured using the Dice similarity coefficient (DSC) and 95% Hausdorff distance. Liver volume accuracy was evaluated using bias, precision, intraclass correlation coefficient, normalized root mean square error (NRMSE), and Bland-Altman analyses.The models trained using both water and fat images performed best, giving DSC = 0.94 and NRMSE = 4.2%. Models trained without the water image as input all performed worse, including in participants with elevated liver fat. Models using the T2-weighted scout images underperformed the Dixon-based models, but provided acceptable performance (DSC ≥ 0.92, NMRSE ≤6.6%) for use in longitudinal pediatric obesity interventions. The model using Dixon water and fat images as input gave the best performance, with results comparable to inter-reader variability and state-of-the-art methods.

Computed tomography myelography technique and spinal morphometry in healthy Yucatan pigs.

Porcine models of spinal cord injury (SCI) have an irreplaceable role in the development of experimental therapies. There is little literature regarding CT myelogram (CTM) techniques in swine and morphometry in miniature swine has not been established. A CT-guided method for performing myelography as well as reference values for spinal morphometry in healthy Yucatan miniature swine is lacking. The goal of this study is to describe a CT-guided method of performing CTM in a porcine model of SCI and to establish spinal morphometric reference values in mature Yucatan pigs. Six healthy, Yucatan sows, 9 months of age, weighing between 39–57.7kg, with no history of spinal disease, spinal injury, or neurologic deficits on physical exam were used in this study. CT myelography was performed in each sow under general anesthesia. CT scout images were used to guide needle placement at the L3-L4 intervertebral site. Once correct needle placement was confirmed using a 1ml test injection, a full dose of iodinated contrast (0.3ml/kg) was injected slowly over a 2-minute time period. Morphometry was performed using area measurements of the spinal cord (SC), vertebral body (VB), dural sac (DS), and vertebral canal (VC) at the mid-body and the intervertebral disc space of each spinal segment. Of the quantitative measurements, the spinal cord surface area had the widest range of values and the greatest coefficient of variance (CV) while those parameters for the vertebral canal had a low CV. Of the morphometric ratios, the DS:VC, had the lowest CV while the spinal cord ratios to DS and VC had the highest (>30). The vertebral canal surface area and the dural space: vertebral canal ratio may serve as reference values in future studies using this animal model.

PHANTOM STUDY OF THE ENTRANCE SURFACE DOSE OF A NEW CT SCOUT ACQUISITION THAT ALSO SERVES AS A TUBE WARM-UP.

We determined the effect of a new scout image acquisition technique ('smart scout'), which also serves as a tube warm-up, on radiation dose and automatic exposure control (AEC) mA settings. The entrance surface dose (ESD) of a chest phantom with and without the smart scout was measured. A conical AEC phantom was scanned in the setting for abdominal CT, and AEC curves were generated. ESD when the smart scout was not used was 0.75mGy at 120kV, 50mA. ESD when using the smart scout was 0.24mGy for a body habitus setting of 'Less', 0.54mGy for 'Moderate' and 0.95mGy for 'More'. When the diameter of the subject was ≥32cm, the mA setting became lower in 'Less'. The smart scout reduced exposure at the 'Less' and Moderate' settings compared to the conventional scout scan.

Reliability of coeliac and superior mesenteric artery origin level in lumbosacral transitional vertebrae detection and vertebral numbering

Objective: To evaluate the value of coeliac artery (CA) and superior mesenteric artery (SMA) origin levels as an anatomic marker in the detection of lumbosacral transitional vertebrae (LSTV) and vertebral enumeration. Patients and Methods: Institutional review board approval was obtained. Routine lumbar magnetic resonance (MR) imaging that included sagittal cervicothoracic scout images in 972 cases were evaluated retrospectively. Six segments were created in the vertebral column with 7 lines. CA and SMA ostiums were localized in these segments. Results: Coeliac artery and SMA levels were detected more caudally in lumbarized S1 and more cranially in sacralized L5 cases compared to non-LSTV cases. Conclusion: Coeliac artery and SMA origin levels are not confidential in consequence of wide variability.

Reconstruction of three-dimensional tomographic patient models for radiation dose modulation in CT from two scout views using deep learning.

A tomographic patient model is essential for radiation dose modulation in x-ray computed tomography (CT). Currently, two-view scout images (also known as topograms) are used to estimate patient models with relatively uniform attenuation coefficients. These patient models do not account for the detailed anatomical variations of human subjects, and thus, may limit the accuracy of intraview or organ-specific dose modulations in emerging CT technologies. The purpose of this work was to show that 3D tomographic patient models can be generated from two-view scout images using deep learning strategies, and the reconstructed 3D patient models indeed enable accurate prescriptions of fluence-field modulated or organ-specific dose delivery in the subsequent CTscans. CT images and the corresponding two-view scout images were retrospectively collected from 4214 individual CT exams. The collected data were curated for the training of a deep neural network architecture termed ScoutCT-NET to generate 3D tomographic attenuation models from two-view scout images. The trained network was validated using a cohort of 55136 images from 212 individual patients. To evaluate the accuracy of the reconstructed 3D patient models, radiation delivery plans were generated using ScoutCT-NET 3D patient models and compared with plans prescribed based on true CT images (gold standard) for both fluence-field-modulated CT and organ-specific CT. Radiation dose distributions were estimated using Monte Carlo simulations and were quantitatively evaluated using the Gamma analysis method. Modulated dose profiles were compared against state-of-the-art tube current modulation schemes. Impacts of ScoutCT-NET patient model-based dose modulation schemes on universal-purpose CT acquisitions and organ-specific acquisitions were also compared in terms of overall image appearance, noise magnitude, and noiseuniformity. The results demonstrate that (1) The end-to-end trained ScoutCT-NET can be used to generate 3D patient attenuation models and demonstrate empirical generalizability. (2) The 3D patient models can be used to accurately estimate the spatial distribution of radiation dose delivered by standard helical CTs prior to the actual CT acquisition; compared to the gold-standard dose distribution, 95.0% of the voxels in the ScoutCT-NET based dose maps have acceptable gamma values for 5 mm distance-to-agreement and 10% dose difference. (3) The 3D patient models also enabled accurate prescription of fluence-field modulated CT to generate a more uniform noise distribution across the patient body compared to tube current-modulated CT. (4) ScoutCT-NET 3D patient models enabled accurate prescription of organ-specific CT to boost image quality for a given body region-of-interest under a given radiation doseconstraint. 3D tomographic attenuation models generated by ScoutCT-NET from two-view scout images can be used to prescribe fluence-field-modulated or organ-specific CT scans with high accuracy for the overall objective of radiation dose reduction or image quality improvement for a given imagingtask.

A prospective study to determine and compare the sizes of the frontal sinus by age and gender

Introduction: Determination of gender and estimation of stature from the skeleton is vital to medicolegal inquiries. CT scan measurements of maxillary and frontal sinuses are thought to be useful for gender determination. The aim of this study is to compare the frontal sinus dimensions and to assess their reliability and accuracy for gender determination using a CT scan. Materials and Methods: A comparative study included cranial Computerized tomography (CT) of 40 patients aged between 18 and 65 years who underwent CT examination of the head and neck for other medical problems that are not related to the frontal sinus. The measurements of the frontal sinus were done in axial and scout images. Results: Our study showed that the maximum depth of frontal sinus in males and females was 10.76 ± 2.12 and 9.23 ± 1.85, respectively, which showed a statistically significant P value (<0.05). The thickness of the anterior wall for males and females was 5.27 ± 1.46 and 5.62 ± 1.60, respectively. There was no statistical significance with respect to the thickness of the anterior wall of the frontal sinus. The maximal anteroposterior length of frontal sinus measured from scout image for males and females were 12.35 ± 3.11 and 10.52 ± 2.15, respectively, which showed a statistically significant P < 0.05. The frontal sinus dimensions were correlated with age subgroups, and there is no statistical significance. Conclusion: We concluded that the dimensions of the frontal sinus could be used for gender dimorphism. This study also proposes the reliability and accuracy of frontal sinus; hence the study proves vital in identifying the gender of a person in forensic anthropology.

Recording Natural Head Position Using Cone Beam Computerized Tomography.

The purpose of this study was to develop a technique to record the natural head position (NHP) of a subject using the scout images of cone beam computerized tomography (CBCT) scans. The first step was to align a hanging mirror with the vertical (XY) plane of the CBCT field-of-view (FOV) volume. Then, two scout CBCT images, at frontal and at sagittal planes, were taken when the subject exhibited a NHP. A normal CBCT scan on the subject was then taken separately. These scout images were used to correct the orientation of the normal CBCT scan. A phantom head was used for validation and performance analysis of the proposed method. It was found that the orientation detection error was within 0.88°. This enables easy and economic NHP recording for CBCT without additional hardware.

Scout it out! Wake-Up Stroke Protocol to Expedite MRI in Stroke Patients

In wake-up stroke patients, magnetic resonance imaging (MRI) is useful to identify patients that would benefit from thrombolytic therapy. Our multidisciplinary stroke team developed and implemented a workflow to rapidly identify patients that are able to safely undergo an MRI exam, thus decreasing time to treatment. We employ a full-body CT scout image in our CT head protocol for acute stroke in order to identify implantable devices and foreign bodies. This protocol highlights the importance of radiology playing an active role on the multidisciplinary stroke team in order to effectively and promptly treat patients.

Comparison of Radiation Dose of Abdomen Pelvis CT with Automatic Exposure Control according to Different Scout Image Acquisition: Standard and Obese Phantom Study

자동노출조절장치를 사용한 복부 CT 검사에서 scout 영상을 획득 시 관전압, 관전류를 변화시켰을 때 실제 검사의 선량 측면에 어떤 영향이 있는지 보고자 하였다. 연구는 G사, S사 두 사의 장비와 standard body phantom, obese body phantom을 사용하여 진행이 되었다. Scout 영상을 획득 시 관전압은 80, 100, 120 kVp, 관전류는 10 ~ 80 mA를 이용하여 적용하였다. 선량 분석은 먼저 복부 CT검사에 AEC 기능이 잘 적용되는지 알아보았고, 팬텀의 단면에 흡수된 선량을 mAs 값으로 그리고 전체 CT 선량 수치도 비교하였다. 그 결과 G사, S사 장비를 이용하여 scout 영상의 획득 시 관전류의 변화는 실제 CT 검사에서 크게 영향을 미치지 않았다. 반면에, 관전압을 변화시킬 때에는 scout 획득 관전압이 낮을수록 실제 CT 검사 시 선량이 증가되는 것을 확인할 수 있었다. 장비를 사용할 때 전체 CT검사의 선량을 줄이기 위해 scout 획득 관전압을 무조건 낮게 설정하여 영상을 획득한다면 실제 CT검사에서 더 많은 선량이 발생하는 것을 초래할 가능성이 있다. 결과적으로 scout 영상 획득 시 관전압의 사용은 실제 CT 검사의 관전압과 가능한 일치시켜야 한다.

Magnetic Resonance Imaging in Cardiac Amyloidosis: Unraveling the Stealth Entity.

Amyloidosis is a systemic disease involving many organs. Cardiac involvement is a significant cause of morbidity and mortality in these patients. Diagnosis of cardiac amyloidosis is based on endomyocardial biopsy which however is invasive and associated with complications. Noninvasive methods of diagnosis include magnetic resonance imaging (MRI) with various methods and sequences involved. Our study aims at describing MRI features of cardiac amyloidosis including new imaging sequences and to prognosticate the patients based on imaging features. We included 35 patients with suspected cardiac amyloidosis who underwent MRI at our center over 4 years. All images were retrieved from our archive and assessed by an experienced radiologist. Common morphological features in our patients included increased wall thickness of left ventricle (LV) (16. 1 ± 4.1 mm), right ventricle (RV) (6.3 ± 1.1 mm), and interatrial septum (6.2 ± 0.8 mm). Global late gadolinium enhancement (LGE) ( n = 21 [65%]) including subendocardial or transmural was the most common pattern followed by patchy enhancement. Global transmural LGE was associated with worse prognosis. Four types of myocardial nulling patterns were observed on postcontrast time to invert (TI) scout imaging: normal nulling pattern (myocardium nulls after blood and coincident with spleen) and abnormal nulling pattern (ANP) which is further divided into three types: Type 1-myocardium nulls before blood pool but coincident with spleen, Type 2-myocardium nulling coincident with blood but not coincident with spleen, and Type 3-features of both Type 1 and Type 2. Type 3 ANP was the most common ( n = 23) nulling pattern in our patients. Cardiac MRI is an essential in noninvasive diagnosis of cardiac amyloidosis. Transmural global LGE serves as a poor prognosticator in these patients. "Three-tier" TI scout imaging is essential to avoid false-negative enhancement results. Type 3 ANP is the most specific nulling pattern in cardiac amyloidosis.

The different failure modes of the connecting elements of the modular hip arthroplasty revision stem Revitan

IntroductionFracture of the femoral stem is the cause of ~1 % of revisions after total hip arthroplasty. The risk increases intrinsically with modularity, whereby modularity is particularly useful in revision arthroplasty. We present 7 cases of failure of a specific modular, tapered, fluted, titanium alloy Revitan stem and analyse the different failure modes. MethodsRetrospective review of all Revitan stems revised at our institutions due to implant failure and analysis of clinical presentation, diagnostic workup, and failure mode. The retrieved components were analyzed by optical and scanning electron microscopy. ResultsA total of 7 cases were included. There was a significant time lag between symptom onset and correct diagnosis. Conventional radiographs and low-dose CT scans (CT scout imaging) were decisive for diagnosis. All failures occurred at the level of the connection between the proximal component and the distal part of the stem. Three different failure modes were identified: loosening of the proximal component, fatigue fracture of the connection pin, and distal loosening of the connection pin. No alterations of the microstructure or deviation from manufacturing specifications regarding dimensions were observed. Failure was caused by mechanical overload. ConclusionConventional radiographs are the mainstay in identifying failed modular stems. Repeated radiographs and low-dose CT scans may be helpful additions. No single modification of the connection will address all possible failure modes. Modularity of revision stems offers advantages up until insertion of the definitive stem. Monoblock definitive stems might overcome the potential mechanical weaknesses of modularity and should be considered in relatively young, heavy and active patients.

Gallstone Ileus in an Adult Male Patient: Computed Tomographic Findings and Case Report

Gallstone ileus is a mechanical intestinal obstruction due to gallstone impaction within the gastrointestinal tract, and responsible for less than 1% of cases of intestinal obstruction. This is a case of a 50-year-old male who was referred for computed tomography of the abdomen on account of abdominal pain, abdominal swelling and discomfort, restlessness, vomiting, constipation, easy fatigability, excess sweating and restlessness. The scout image of the computed tomography (CT) demonstrated linear streaks and foci of radiolucency beneath and around the 10th and 11th anterior ribs on the right most likely pneumobilia. Air distended bowel loops were also demonstrated. Serial axial slides demonstrated an impacted calculus measuring about 30mm in widest transverse diameter in the right iliac region most probably the ileocecal valve region extending in to the cecum with associated dilated bowel loops showing multiple air-fluid levels raising a suspicion of mechanical bowel obstruction. The gall bladder measures about 50mm x 30mm in cranio-caudal and mediolateral diameter, with turbid contents and thickened walls of about 4mm most likely from cholecystitis. A diagnosis of mechanical bowel obstruction following an impacted calculus at the ileocecal valve was entertained; Gallstone ileus in a 50-year-old man. The patient had surgical treatment, this comprised of exploratory laparotomy with entero-lithotomy, fistula repair and cholecystectomy. The patient did well post-operatively and was discharged home subsequently and advised on follow-up visits. We present a case of mechanical bowel obstruction following an impacted gall stone at the ileocecal valve in a 50-year-old male patient.

A deep-learning method using computed tomography scout images for estimating patient body weight

Body weight is an indispensable parameter for determination of contrast medium dose, appropriate drug dosing, or management of radiation dose. However, we cannot always determine the accurate patient body weight at the time of computed tomography (CT) scanning, especially in emergency care. Time-efficient methods to estimate body weight with high accuracy before diagnostic CT scans currently do not exist. In this study, on the basis of 1831 chest and 519 abdominal CT scout images with the corresponding body weights, we developed and evaluated deep-learning models capable of automatically predicting body weight from CT scout images. In the model performance assessment, there were strong correlations between the actual and predicted body weights in both chest (ρ = 0.947, p < 0.001) and abdominal datasets (ρ = 0.869, p < 0.001). The mean absolute errors were 2.75 kg and 4.77 kg for the chest and abdominal datasets, respectively. Our proposed method with deep learning is useful for estimating body weights from CT scout images with clinically acceptable accuracy and potentially could be useful for determining the contrast medium dose and CT dose management in adult patients with unknown body weight.

A pilot study: Quantify lung volume and emphysema extent directly from two-dimensional scout images.

The potential to compute volume metrics of emphysema from planar scout images was investigated in this study. The successful implementation of this concept will have a wide impact in different fields, and specifically, maximize the diagnostic potential of the planar medical images. We investigated our premise using a well-characterized chronic obstructive pulmonary disease (COPD) cohort. In this cohort, planar scout images from computed tomography (CT) scans were used to compute lung volume and percentage of emphysema. Lung volume and percentage of emphysema were quantified on the volumetric CT images and used as the "ground truth" for developing the models to compute the variables from the corresponding scout images. We trained two classical convolutional neural networks (CNNs), including VGG19 and InceptionV3, to compute lung volume and the percentage of emphysema from the scout images. The scout images (n=1,446) were split into three subgroups: (1) training (n=1,235), (2) internal validation (n=99), and (3) independent test (n=112) at the subject level in a ratio of 8:1:1. The mean absolute difference (MAD) and R-square (R2) were the performance metrics to evaluate the prediction performance of the developed models. The lung volumes and percentages of emphysema computed from a single planar scout image were significantly linear correlated with the measures quantified using volumetric CT images (VGG19: R2=0.934 for lung volume and R2=0.751 for emphysema percentage, and InceptionV3: R2=0.977 for lung volume and R2=0.775 for emphysema percentage). The mean absolute differences (MADs) for lung volume and percentage of emphysema were 0.302±0.247L and 2.89±2.58%, respectively, for VGG19, and 0.366±0.287L and 3.19±2.14, respectively, for InceptionV3. Our promising results demonstrated the feasibility of inferring volume metrics from planar images using CNNs.

Bismuth breast-shield use in chest computed tomography for efficient dose reduction and sufficient image quality.

Background:Radiosensitivity in the breasts increases the risk of carcinogenesis from exposure to the ionizing radiation of computed tomography (CT) administered in the course of medical attention. Bismuth shielding techniques have been used to reduce radiation, but image noise increased, degrading image quality.Purpose:The aim of this study was to investigate how the use of iterative reconstruction (IR) combined with bismuth shielding influences image quality.Materials and Methods:Women aged at least 20 years with body mass indexes <28 were recruited and randomly assigned to 1 of 3 CT scanning protocols without shielding, with a bismuth breast shield before the scout view, or with a bismuth breast shield after the scout view. All obtained images were reconstructed using an IR algorithm. To evaluate radiation dose, 2 Gafchromic films were placed over the clothes, 1 near each nipple.Results:Average dose reduction was significant (27.99%, P < .05) when bismuth shielding was applied after the scout view. Using the contrast-to-noise ratio, the image quality was found to be superior when the IR algorithm was applied. Using quantitative evaluations by 2 radiologists applying a 4-point Likert scale, significant differences in image quality were not found among the 3 protocols.Conclusion:Bismuth breast shields, particularly when used after acquiring scout images, are effective at reducing radiation dose without undermining the diagnostic value of the images when the IR technique is applied.

The CT scout view: complementary value added to abdominal CT interpretation.

Computed tomography (CT) scout images, also known as CT localizer radiographs, topograms, or scanograms, are an important, albeit often overlooked part of the CT examination. Scout images may contain important findings outside of the scanned field of view on CT examinations of the abdomen and pelvis, such as unsuspected lung cancer at the lung bases. Alternatively, scout images can provide complementary information to findings within the scanned field of view, such as characterization of retained surgical foreign bodies. Assessment of scout images adds value and provides a complementary "opportunistic" review for interpretation of abdominopelvic CT examinations. Scout image review is a useful modern application of conventional abdominal radiograph interpretation that can help establish a diagnosis or narrow a differential diagnosis. This review discusses the primary purpose and intent of the CT scout images, addresses standard of care and bias related to scout image review, and presents a general systematic approach to assessing scout images with multiple illustrative examples, including potential pitfalls in interpreting scout images.