Three-dimensional Postprocessing Research Articles

Computed tomography and transthoracic echocardiography for assessment of left ventricle geometry in patients with aortic valve stenosis.

Standard transthoracic echocardiography (TTE) often is not sufficient to properly visualize the geometry of the left ventricle. One of the clinical imaging modalities that can be used for this purpose is contrast-enhanced, electrocardiologically gated cardiac computed tomography (CT). To compare cardiac CT and TTE as tools for assessing geometry and function of the left ventricle in patients with severe aortic stenosis. We analyzed 58 consecutive patients (43.1% males, mean age 81.4 ±6.0 years) with severe aortic stenosis, who underwent both cardiac CT and TTE. Left ventricle major axis length is significantly longer in CT than in TTE (81.5 ±11.7 mm vs. 74.6 ±13.5 mm, p = 0.004). No difference was found in end-systolic left ventricle volume between the two imaging methods, while end-diastolic volume of the left ventricle was significantly larger when measured in CT than in both 2D biplane and 3D triplane TTE. The stroke volume was not different between the 2D biplane TTE and CT. No significant difference was found between CT and TTE in the calculation of ejection fraction and LV mass/indexed LV mass (p > 0.05). The use of three-dimensional postprocessing provides a very accurate image of heart structures in CT, which in some aspects may significantly differ from the values estimated by TTE.

Role of CT in the Pre- and Postoperative Assessment of Conotruncal Anomalies.

Conotruncal anomalies, also referred to as outflow tract anomalies, are congenital heart defects that result from abnormal septation of the great vessels' outflow tracts. The major conotruncal anomalies include tetralogy of Fallot, double-outlet right ventricle, transposition of the great arteries, truncus arteriosus, and interrupted aortic arch. Other defects, which are often components of the major anomalies, include pulmonary atresia with ventricular septal defect, pulmonary valve agenesis, aortopulmonary window, and double-outlet left ventricle. CT has emerged as a robust diagnostic tool in preoperative and postoperative assessment of various congenital heart diseases, including conotruncal anomalies. The data provided with multidetector CT imaging are useful for treatment planning and follow-up monitoring after surgery or intervention. Unlike echocardiography and MRI, CT is not limited by a small acoustic window, metallic devices, and need for sedation or anesthesia. Major advances in CT equipment, including dual-source scanners, wide-detector scanners, high-efficiency detectors, higher x-ray tube power, automatic tube current modulation, and advanced three-dimensional postprocessing, provide a low-risk, high-quality alternative to diagnostic cardiac catheterization and MRI. This review explores the various conotruncal anomalies and elucidates the role of CT imaging in their pre- and postoperative assessment. Keywords: CT, CT Angiography, Stents, Pediatrics © RSNA, 2022.

Three-dimensional perception of cinematic rendering versus conventional volume rendering using CT and CBCT data of the facial skeleton

The aim of this exploratory study is to analyse whether three-dimensional cinematic rendering image reconstructions offer advantages over conventional volume rendering in the visualisation of cone beam computed tomography (CBCT) and computed tomography (CT) images of the facial skeleton. This is of interest, as some information gets lost during the rendering process. This especially applies to structures in the background of the image and some surface information which can be lost. The commonly applied two-dimensional representation of CBCT or CT images in three different axes requires experience for interpretation. Cinematic rendering is a new three-dimensional post processing reconstruction technique, creating photo realistic visualisations, thus possibly enabling an easier interpretation of the images.In this study, ten investigators assessed ten separate patient cases of the orofacial skeleton. For each case, a conventional volume rendering image reconstruction and a cinematic rendering reconstruction of the same area was created. A specially designed questionnaire assessed both objective and subjective criteria of image perception. Objective criteria were assessed by predefined questions on the visual perception of anatomical image characteristics, showing the two reconstruction types of each case randomly to the investigators in two sessions. Subjective criteria were assessed via a visual analogue scale, showing both reconstructions simultaneously in a third session.The results show that cinematic rendering offers advantages especially in the evaluation of depth perception and three-dimensionality. Volume rendering shows advantages in surface sharpness. Cinematic Rendering was subjectively rated higher for almost all reconstructions. The cinematic rendering process however may cause loss of information and blurring of surfaces compared to volume rendering. With respect to the subjective impression, cinematic rendering scored better than volume rendering. The visualisation is perceived as being very close to reality.

Value of radiomic analysis of data from magnetic resonance elastography for diagnosing fibrosis stages in patients with hepatitis B/C

To evaluate the value of radiomic analysis of data from MR elastography (MRE) for diagnosing stages of fibrosis in patients with chronic hepatitis B/C (CHB/CHC). MRE images from 140 CHB/CHC patients with pathologically proven F0–F4 hepatic fibrosis stages were retrospectively analyzed, which is approved by our Institutional Review Board (IRB). A total of 364 radiomic features were extracted from spin-echo echo planar imaging with three-dimensional postprocessing (EPI3D) and gradient recalled echo with two-dimensional postprocessing (GRE2D) MRE data, including histogram parameters (HPs), gray level co-occurrence matrix (GLCM), and gray level run length matrix. Feature selection (significance test and correlation analysis) and classification (logistic regression models) were performed to stage ≥ F1, ≥ F2, ≥ F3 and F4, with a leave-one-out-based cross-validation method. Receiver operating characteristic analysis including areas under the curves (AUCs) was performed. Univariate analysis showed the best-performing features for classifying fibrosis stages were HPs (AUC range 0.798–0.929 for EPI3D and 0.727–0.916 for GRE2D). In multivariate radiomic analysis, AUCs for diagnosing fibrosis of ≥ F1, ≥ F2, ≥ F3 and cirrhosis (F4) were 0.888, 0.934, 0.924 and 0.948 for EPI3D MRE, and 0.887, 0.867, 0.892 and 0.941 for GRE2D MRE, which were slightly higher than that of EPI and GRE stiffness for each fibrosis stage (EPI 0.816, 0.924, 0.870 and 0.918; GRE 0.882, 0.800, 0.865 and 0.911). The AUCs of the EPI3D model were significantly higher than GRE2D model for staging clinically significant fibrosis (0.934 vs 0.867, P = 0.030) and advanced fibrosis (0.924 vs 0.892, P = 0.029). Radiomic analysis of MRE facilitates fibrosis classification in CHB/CHC patients, especially for identifying intermediate fibrosis, with a higher diagnostic performance by the EPI3D MRE.

Establishing and Running a Three-dimensional and Advanced Imaging Laboratory.

Multidetector CT technology has advanced during the past 2 decades from single-digit numbers of sections to 320-section CT scanners. The ability to perform three-dimensional (3D) postprocessing of acquired data has accompanied this technical progress. Multiple considerations are involved in developing and deploying a 3D and advanced imaging laboratory to provide postprocessing for both CT and MRI examinations. Establishing and running a 3D laboratory requires administrators to buy into the process and also requires regular input from radiologists and other stakeholders. Technologists with prior 3D experience are rare, and extensive immersive training is typically required. Laboratory space and equipment must be maintained and updated regularly to continue to meet stakeholders' needs. Postprocessing protocols must be established and reviewed periodically. Quality control is also necessary to ensure that postprocessing outputs adhere to the protocols. Laboratory technologists can also provide postprocessing support for research examinations and can lend their technical expertise to research projects. Regular review of laboratory productivity is essential to ensure longevity and availability of necessary resources (human, environmental, and technical). As the technologies for the imaging equipment, the picture archiving and communication system, and postprocessing continue to advance, the role of the 3D laboratory will also evolve to include other services. This evolution will affect ongoing training of technologists, as well as the requirements when new technologists are hired. The 3D laboratory is often positioned to take on novel technology and augment radiologists' workflow as new modalities and techniques enter the clinical workflow. ©RSNA, 2018.

The birth canal: correlation between the pubic arch angle, the interspinous diameter, and the obstetrical conjugate: a computed tomography biometric study in reproductive age women

Background: Assessment of pelvic configuration is an important factor in the prediction of a successful vaginal birth. However, manual evaluation of the pelvis is practically a vanishing art, and imaging techniques are not available as a real-time bed-side tool. Unlike the obstetrical conjugate diameter (OC) and inter spinous diameter (ISD), the pubic arch angle (PAA) can be easily measured by transperineal ultrasound.Objectives: Three-dimensional computed tomography bone reconstructions were used to measure the three main birth canal diameters, evaluate the correlation between them, and establish the normal reference range for the inlet, mid-, and pelvic outlet.Study design: Measurements of the PAA, obstetric conjugate (OC), and ISD were performed offline using three-dimensional post processing reconstruction in bone algorithm application of the pelvis on examinations performed for suspected renal colic in nonpregnant reproductive age woman. The mean of two measurements was used for statistical analysis which included reproducibility of measurements, regression curve estimation between PAA, OC, and ISD, and calculation of the respective reference range centiles for each PAA degree.Results: Two hundred ninety-eight women comprised the study group. The mean ± SD of the PAA, ISD, and OC were 104.9° (±7.4), 103.8 mm (±7.3), and 129.9 mm (±8.3), respectively. The intra- and interobserver agreement defined by the intraclass correlation coefficient (ICC) was excellent for all parameters (range 0.905–0.993). A significant positive correlation was found between PAA and ISD and between PAA and OCD (Pearson’s correlation = 0.373 (p < .001), and 0.163 (p = .022), respectively). The best regression formula was found with quadratic regression for inter spinous diameter (ISD): 34.122778 + (0.962182*PAA − 0.002830*PAA2), and linear regression for obstetric conjugate (OC): 110.638397 + 0.183156*PAA. Modeled mean, SD, and reference centiles of the ISD and OCD were calculated using the above regression models as function of the PAA.Conclusions: We report significant correlation between the three pelvic landmarks with greatest impact on the prediction of a successful vaginal delivery: the PAA which is easily measured sonographically and the ISD and OC which are not measurable by ultrasound. This correlation may serve as a basis for future studies to assess its utility and prognostic value for a safe vaginal delivery.

A web service system supporting three-dimensional post-processing of medical images based on WADO protocol.

Three-dimensional post-processing operations on the volume data generated by a series of CT or MR images had important significance on image reading and diagnosis. As a part of the DIOCM standard, WADO service defined how to access DICOM objects on the Web, but it didn't involve three-dimensional post-processing operations on the series images. This paper analyzed the technical features of three-dimensional post-processing operations on the volume data, and then designed and implemented a web service system for three-dimensional post-processing operations of medical images based on the WADO protocol. In order to improve the scalability of the proposed system, the business tasks and calculation operations were separated into two modules. As results, it was proved that the proposed system could support three-dimensional post-processing service of medical images for multiple clients at the same moment, which met the demand of accessing three-dimensional post-processing operations on the volume data on the web.

Development of a noise reduction filter algorithm for pediatric body images in multidetector CT.

Recently, several types of post-processing image filter which was designed to reduce noise allowing a corresponding dose reduction in CT images have been proposed and these were reported to be useful for noise reduction of CT images of adult patients. However, these have not been reported on adaptation for pediatric patients. Because they are not very effective with small (<20 cm) display fields of view, they could not be used for pediatric (e.g., premature babies and infants) body CT images. In order to solve this restriction, we have developed a new noise reduction filter algorithm which can be applicable for pediatric body CT images. This algorithm is based on a three-dimensional post processing, in which output pixel values are calculated by multi-directional, one-dimensional median filters on original volumetric datasets. The processed directions were selected except in in-plane (axial plane) direction, and consequently the in-plane spatial resolution was not affected by the filter. Also, in other directions, the spatial resolutions including slice thickness were almost maintained due to a characteristic of non-linear filtering of the median filter. From the results of phantom studies, the proposed algorithm could reduce standard deviation values as a noise index by up to 30% without affecting the spatial resolution of all directions, and therefore, contrast-to-noise ratio was improved by up to 30%. This newly developed filter algorithm will be useful for the diagnosis and radiation dose reduction of pediatric body CT images.

Midterm outcomes of femoral arteries after percutaneous endovascular aortic repair using the Preclose technique

Percutaneous access during endovascular aortic repair has been shown to be feasible and safe using a suture-mediated closure device ("Preclose" technique) for closure of up to 24F introducer sheaths. The purpose of this study is to examine the late outcomes of those femoral arteries repaired in this manner. The Preclose technique has been previously described. Briefly, the technique involves two Perclose Proglide devices deployed in the femoral artery prior to insertion of the large diameter introducer sheath and then closure of the arteriotomy by tying down knots of the Proglide following removal of the sheath. The medical records of all patients who underwent endovascular aortic repairs using the Preclose technique between December 2004 and August 2007 were reviewed. Follow-up protocol consisted of computed tomography (CT) angiograms performed at 1, 6, and 12 months, and annually thereafter. All Preclose patients who had at least a 6-month postoperative scan were included in the study. For each patient, the most recent postoperative scan was compared with the preoperative scan for evidence of any new anatomic abnormalities of the femoral artery such as dissection, stenosis, or pseudoaneurysm. Three-dimensional post processing with multiplanar reconstructions was also performed as necessary to confirm axial scan findings. A total of 292 patients underwent percutaneous endovascular aortic repairs (TEVAR-125, EVAR-167). Four hundred thirty-two femoral arteries were closed with 870 devices. Four hundred eighteen vessels were approximated with two devices, while 30 arteries required three devices for hemostasis and an additional four vessels only required a single device. Two hundred seventy-eight (64.3%) vessels were accessed with sheaths 18 to 24F. Four hundred eight femoral arteries (94.4%) were closed successfully with the Preclose technique. There were 100 patients (TEVAR-35, EVAR-65) who had adequate postoperative CT scan at 6-months or later. The mean follow up was 11.6 +/- 5.0 months. Of the 156 femoral arteries in these 100 patients repaired using the Preclose technique, there were 3 late complications in 3 patients, 1 asymptomatic femoral artery dissection, and 2 femoral artery pseudoaneurysms requiring surgical repair, resulting in a late complication rate of 1.92% (3/156). Percutaneous closure of femoral arteries after large diameter introducer sheaths using the Preclose technique has a low incidence of early and late complications related to the closure site.

Role of MRI in the management of patients with nephroblastoma

Magnetic resonance imaging (MRI) presents the main diagnostic tool for differentiation and staging of renal tumors in childhood. Nephroblastoma is the most common malignant tumor in children. Radiological findings play an important role in therapy study trials of SIOP (International Society of Pediatric Oncology), especially for indicating preoperative chemotherapy. In the past few years MRI has gained great importance in imaging of nephroblastoma and has replaced computed tomography (CT). The aim of this review is to present the diagnostic possibilities of MRI in relation to the requirements of therapy studies. For nephroblastoma, MRI provides important information about tumor extent and distant metastasis. A special focus of MRI in distant staging is venous extent of the tumor into the inferior vena cava. In addition, MRI has an important role in monitoring chemotherapy and in preoperative planning by volume rendering and three-dimensional postprocessing.

Computed Tomography Angiography and Computed Tomography Perfusion in Ischemic Stroke: A Step-by-Step Approach to Image Acquisition and Three-Dimensional Postprocessing

Recent technical advances in both image acquisition and postprocessing have enabled computed tomography angiography (CTA) with computed tomography perfusion to become front-line tools for acute stroke evaluation in many institutions. This article provides a step-by-step approach to utilizing these technologies, particularly in the rapid triage of appropriate stroke patients to reperfusion therapies. The specific contrast injection, image acquisition, and 3D postprocessing protocols for high-quality CTA, currently in use at our institution, are delineated. An important point of emphasis is how preliminary angiographic and cerebral perfusion observations can be made immediately at the scanner to expedite emergent therapy. Also explored is the manner in which a dedicated 3D lab can support a high clinical volume, including a large percentage of emergent studies. An accurate yet time-efficient approach for the neuroradiologist to integrate 3D interpretation with CTA source data review is offered. Several important imaging and interpretive pitfalls in stroke CTA are illustrated.

Volume Rendering versus Maximum Intensity Projection in CT Angiography: What Works Best, When, and Why

The introduction and widespread availability of 16-section multi-detector row computed tomographic (CT) technology and, more recently, 64-section scanners, has greatly advanced the role of CT angiography in clinical practice. CT angiography has become a key component of state-of-the-art imaging, with applications ranging from oncology (eg, staging of pancreatic or renal cancer) to classic vascular imaging (eg, evaluation of aortic aneurysms and renal artery stenoses) as well as newer techniques such as coronary artery imaging and peripheral runoff studies. With an average of 400-1000 images in each volume data set, three-dimensional postprocessing is crucial to volume visualization. Radiologists now have workstations that provide capabilities for evaluation of these data sets by using a range of software programs and processing tools. Although different systems have unique capabilities and functionality, all provide the options of volume rendering and maximum intensity projection for image display and analysis. These two postprocessing techniques have different advantages and disadvantages when used in clinical practice, and it is important that radiologists understand when and how each technique should be used.

“All‐in‐one” imaging protocols for the evaluation of potential living liver donors: Comparison of magnetic resonance imaging and multidetector computed tomography

In order to compare the performance of "all-in-one" magnetic resonance imaging (MRI) and "all-in-one" multidetector computed tomography (MDCT) in the preharvest evaluation 25 potential living donors underwent both MRI and MDCT. MRI was performed on a high-performance 1.5-T scanner, computed tomography (CT) on a 4-row multidetector-scanner. Both scan protocols included angiography of the arterial and venous hepatic systems. CT additionally included infusion of a biliary contrast agent. Data analysis was performed by 4 reviewers, based on source images, multiplanar reformats, and three-dimensional (3D) postprocessing. Determination of image quality was based on a 4-point image quality rating (IQR) scale, ranging from 1 = nondiagnostic to 4 = excellent. Preoperative and intraoperative (n = 13) findings were correlated. Magnetic resonance (MR) examinations were generally well tolerated. Within the CT scan, 2 candidates presented moderate adverse reaction to the biliary contrast agent. MRI and CT showed the same benign parenchymal lesions (IQR MR: 3.7; IQR CT: 3.4). Determination of liver volumes was easier based on CT (IQR MR: 3.3; IQR CT: 3.6). Magnetic resonance angiography (MRA) revealed 10 variants of the arterial liver supply (IQR: 3.0) and computed tomographic angiography (CTA) revealed 13 variants (IQR: 3.5). Magnetic resonance cholangiopancreatography (MRCP) identified 4 biliary variants (IQR: 1.3) and CT cholangiography identified 17 (IQR: 3.5). MRI and CT each showed 4 hepatic and portal venous variants (IQR MR: 3.4, CT: 2.8). CT and MR findings correlated well with intraoperative findings. In conclusion, both techniques proved to be efficient to evaluate potential living liver donors' anatomy in a single diagnostic step. The main advantage of CT lies in the ability to accurately assess the biliary anatomy.

3-D endobronchial ultrasonography—A post mortem study

Endobronchial ultrasonography (EBUS) using balloon-embedded probes may cause airway obstruction and requires a rapid scanning procedure. Three-dimensional (3-D) postprocessing of sequential 2-D images may allow detailed studies on a rapidly acquired image volume. We applied a 3-D reconstruction program on EBUS recordings acquired with a radial-scanning probe during a controlled pullback procedure in water-filled airways in five corpses. The aim was to acquire EBUS images under optimized conditions and to test a 3-D software program for postprocessing. Under post mortem conditions, 3-D images were obtained, allowing any-plane imaging and measurements, application of different rendering and visualization algorithms and merging of overlapping volumes. (E-mail: alf.andreassen@helse-bergen.no)

Coarctation and aorto-aortic bypass: three-dimensional post-processing using multidetector row computed tomography

We present the case of a 61-year-old man with a history of dyspnea and disparity in blood pressure of the arms and legs due to a stenotic biscupid aortic valve and a hemodynamically relevant restenosis of a resected coarctation. The coarctation was treated with an extra-anatomic transdiaphragmal aorto-aortic bypass graft. At the same time, the biscupid aortic valve was replaced. Postoperative follow-up contrast-enhanced multidetector row computed tomography (MDCT) and three-dimensional (3D) postprocessing of the axial data sets using the volume-rendering technique was performed. This case of complex vascular structures demonstrates the potency of MDCT combined with the 3D visualization technique.

Multi-detector row CT evaluation of living renal donors prior to laparoscopic nephrectomy.

Since its introduction in 1995, laparoscopic nephrectomy has become the preferred technique at many medical centers for the harvesting of kidneys from living donors for transplantation. Because the field of view at laparoscopic surgery is limited, preoperative radiologic evaluation of the donor's anatomy---the renal veins and arteries, collecting system, and parenchyma--is critical. Spiral computed tomographic (CT) angiography is a fast, safe, minimally invasive, and generally accepted method for preoperative evaluation of the renal vessels. Multi-detector row CT scanners offer shorter image acquisition time, narrower collimation, better spatial resolution, and less tube heating than do single-detector row CT scanners. Multi-row scanners also provide more complete anatomic coverage, increased contrast enhancement of the arteries, and greater longitudinal spatial resolution--all of which are important both for accurate imaging of the renal vasculature and for three-dimensional postprocessing of image data. Dual-phase multi-detector row CT angiography combined with three-dimensional postprocessing enables minimally invasive and highly accurate depiction of the preoperative donor anatomy. To make the most effective use of this method, radiologists must be familiar with its technical aspects, advantages, and potential pitfalls. They also must be able to identify variations in vasculature and in renal and extrarenal anatomy that are important for laparoscopic donor nephrectomy.

Radiological emergency room management with emphasis on multidetector-row CT

Trauma is the fifth leading cause of death after disease of the cardiovascular system, malignomas and disease of the respiratory and digestive system. The management of severely injured patients, including radiological imaging, is a matter of ongoing development. In particular, as for the imaging modalities, multidetector-row CT represents a substantial refinement in the diagnostic work-up of multitrauma patients. Sufficient therapy within the first hour after trauma increases the patient's chances for survival significantly. Thus, therapeutic procedures and diagnostic evaluation have to be concomitant events, performed by a multidisciplinary team, namely trauma surgeon, anesthesiologist and, last but not least, radiologist. The increased performance of multidetector-row CT leads to increased spatial resolution, which is a prerequisite for sophisticated two- and three-dimensional postprocessing. The increased volume coverage speed allows for comprehensive whole-body CT at still high levels of spatial resolution, resulting in significant spare of time which influences patient's survival. Using this technique conventional imaging such as plane film or angiography may be omitted.

Optimization of volume rendered three-dimensional ultrasound and four-dimensional ultrasound post processing variables to improve conspicuity of targets and devices for interventional applications. a phantom model

Optimization of volume rendered three-dimensional ultrasound and four-dimensional ultrasound post processing variables to improve conspicuity of targets and devices for interventional applications. a phantom model