Planar Reformation Research Articles

The Use of Closure Devices for Aortic Stent-Graft Insertion: Outcomes Following a Paradigm Shift to Percutaneous Access in a Tertiary Vascular Center.

This retrospective case series aims to evaluate the efficacy of the Perclose ProGlide system for postoperative hemostasis following aortic stent-graft insertion. A prospectively maintained database of patients with a minimum follow-up of 12 months following percutaneous aortic procedures was interrogated. Preprocedural computed tomography (CT) scans were reviewed to assess existing stenosis in the common femoral artery (CFA). Arteries with an estimated stenosis of greater than 25% on visual inspection underwent quantification using multiplanar and curved planar reformation. The preoperative and 1-year follow-up CTs of these patients were assessed for change in stenosis. Analysis was performed by 2 independent reviewers, with senior authors reviewing any discrepancies. One hundred forty-two endovascular aortic aneurysm repairs (EVARs) were performed. The ProGlide system was used in 235 arteries, yielding a high success rate in obtaining postprocedural hemostasis (94%). There were 13 postprocedural access-related complications, including 5 patients requiring surgical closure due to inadequate seal. Two patients required thrombectomy due to distal embolization. One patient required CFA endarterectomy at 6 months for the treatment of preexisting short distance claudication. Vessel analysis was performed in 31 arteries. Mean preoperative stenosis was 32% (range: 20%-57%). Mean postoperative stenosis was 32% (21%-57%). No significant change in degree of stenosis was detected (defined as a 5% change). The ProGlide system yielded a high success rate in obtaining postoperative hemostasis with low rate of conversion to surgical closure and low complication rates. There was no evidence of worsening vessel stenosis in arteries with preprocedural stenotic disease. Level 4, Case Series.

Aortic and Internal Carotid Atherosclerosis in Patients with Carotid Stenosis: Semiautomatic Volumetric Analysis of Low-Attenuation Plaque on Curved Planar Reformations Using MDCT Angiographic Data.

This retrospective study included 65 patients who underwent multidetector computed tomography (MDCT) carotid angiography; 28 patients were <70 years old (group 1), and 37 were ≥70 years old (group 2). Each low-attenuation (<30 Hounsfield units [HU]) plaque volume (LPV) and total uncalcified plaque volume ([TUPV] ≤150 HU) were semiautomatically measured on each aortic arch and internal carotid artery (ICA) curved planar reformations (CPR), using MDCT angiographic data. Correlation coefficients were employed to assess the impact of each plaque volume on various factors including ICA stenosis. The correlations (r > 0.5) were observed between aortic LPV and each ICA stenosis ratio and >30% stenosis in group 1, between aortic TUPV and male gender in group 1, and between ICA-TUPV and each aortic TUPV or the largest plaque thickness in group 2. Marginal correlations were observed between hyperlipidemia and aortic LPV and ICA-TUPV in group 1. There was no association between cerebral infarction and the aortic and ICA plaques. Both the aortic arch and ICA plaque volumes can be measured clinically. The increasing aortic LPV may be a significant factor associated with the development of ICA stenosis in patients younger than 70 years old.

Association Between Flat-Panel Computed Tomographic Imaging–Guided Place-Pitch Mapping and Speech and Pitch Perception in Cochlear Implant Users

Cochlear implant users generally display poor pitch perception. Flat-panel computed tomography (FPCT) has recently emerged as a modality capable of localizing individual electrode contacts within the cochlea in vivo. Significant place-pitch mismatch between the clinical implant processing settings given to patients and the theoretical maps based on FPCT imaging has previously been noted. To assess whether place-pitch mismatch is associated with poor cochlear implant-mediated pitch perception through evaluation of an individualized, image-guided approach toward cochlear implant programming on speech and music perception among cochlear implant users. A prospective cohort study of 17 cochlear implant users with MED-EL electrode arrays was performed at a tertiary referral center. The study was conducted from June 2016 to July 2017. Theoretical place-pitch maps using FPCT secondary reconstructions and 3-dimensional curved planar re-formation software were developed. The clinical map settings (eg, strategy, rate, volume, frequency band range) were modified to keep factors constant between the 2 maps and minimize confounding. The acclimation period to the maps was 30 minutes. Participants performed speech perception tasks (eg, consonant-nucleus-consonant, Bamford-Kowal-Bench Speech-in-Noise, vowel identification) and a pitch-scaling task while using the image-guided place-pitch map (intervention) and the modified clinical map (control). Performance scores between the 2 interventions were measured. Of the 17 participants, 10 (58.8%) were women; mean (SD) was 59 (11.3) years. A significant median increase in pitch scaling accuracy was noted when using the experimental map compared with the control map (4 more correct answers; 95% CI, 0-8). Specifically, the number of pitch-scaling reversals for notes spaced at 1.65 semitones or greater decreased when an image-based approach to cochlear implant programming was used vs the modified clinical map (4 mistakes; 95% CI, 0.5-7). Although there was no observable median improvement in speech perception during use of an image-based map, the acute changes in frequency allocation and electrode channel deactivations used with the image-guided maps did not worsen consonant-nucleus-consonant (-1% correct phonemes, 95% CI, -2.5% to 6%) and Bamford-Kowal-Bench Speech-in-Noise (0.5-dB difference; 95% CI, -0.75 to 2.25 dB) median performance results relative to the clinical maps used by the patients. An image-based approach toward ochlear implant mapping may improve pitch perception outcomes by reducing place-pitch mismatch. Studies using a longer acclimation period with chronic stimulation over months may help assess the full range of the benefits associated with personalized image-guided cochlear implant mapping.

Automated Curved and Multiplanar Reformation for Screening of the Proximal Coronary Arteries in MR Angiography

Congenital anomalies of the coronary ostia can lead to sudden death. A screening solution would be useful to prevent adverse outcomes for the affected individuals. To be considered for integration into clinical routine, such a procedure must meet strict constraints in terms of invasiveness, time and user interaction. Imaging must be fast and seamlessly integrable into the clinical process. Non-contrast enhanced coronary magnetic resonance angiography (MRA) is well suited for this. Furthermore, planar reformations proved effective to reduce the acquired volumetric datasets to 2D images. These usually require time consuming user interaction, though. To fulfill the aforementioned challenges, we present a fully automated solution for imaging and reformatting of the proximal coronary arteries which enables rapid screening of these. The proposed pipeline consists of: (I) highly accelerated single breath-hold MRA data acquisition, (II) coronary ostia detection and vessel centerline extraction, and (III) curved planar reformation of the proximal coronary arteries, as well as multiplanar reformation of the coronary ostia. The procedure proved robust and effective in ten volunteer data sets. Imaging of the proximal coronary arteries took 24 ± 5 s and was successful within one breath-hold for all patients. The extracted centerlines achieve an overlap of 0.76 ± 0.18 compared to the reference standard and the average distance of the centerline points from the spherical surface for reformation was 1.1 ± 0.51 mm. The promising results encourage further experiments on patient data, particularly in coronary ostia anomaly screening.

Automated determination of cardiac rest period on whole-heart coronary magnetic resonance angiography by extracting high-speed motion of coronary arteries

PurposeThe aim of the present study was to develop an automated system for determining the cardiac rest period during whole-heart coronary magnetic resonance angiography (CMRA) examination. Materials and methodsTen healthy male volunteers (25–51 years old, 50–77 beats/min heart rate) were enrolled in this prospective study. A motion area map was generated from a cine image set by extracting high-speed component of cardiac motion, and it was used to specify the rest period in the proposed CMRA. In conventional CMRA, the rest period was determined based on the visual inspection of cine images. Agreement of the start time, end time, and trigger time between the two methods was assessed by the Bland-Altman plot analysis. Two observers visually evaluated the quality of the curved planar reformation (CPR) image of the coronary arteries. ResultsThe proposed method significantly prolonged the start time (mean systematic difference 37.7 ms, P < 0.05) compared with the conventional method. Good agreement was observed for the end time (mean systematic difference 8.9 ms) and trigger time (mean systematic difference −28.8 ms) between the two methods. A significantly higher image quality (P < 0.05) was provided for the left circumflex artery in the proposed CMRA (mean grading score 3.88) than in conventional CMRA (mean grading score 3.68). ConclusionOur system enabled detection of the rest period automatically without operator intervention and demonstrated somewhat higher image quality compared with conventional CMRA. Its use may be useful to improve the imaging workflow for CMRA in clinical practice.

Comparison of Image Enlargement according to 3D Reconstruction in a CT Scan: Using an Aneurysm Phantom

The purpose of this study was to evaluate the magnification of an aneurysm size according to the type of reconstruction of a 3-dimensional Computed tomography (CT) scan. The aneurysm was prepared by mixing angiografin and saline in a rubber balloon of 51 mm in width and 77 mm in length. The balloon was placed in a plastic barrel and fixed with paraffin. CT scans were used to obtain scan data of the balloons, and the multi planar reformation (MPR), maximum intensity projection (MIP), shaded surface display (SSD), and volume rendering technique (VRT) were obtained by using 3D reconstruction. The size of the measurement points was measured and compared with the measured values of the actual aneurysm phantom. As a result of the comparison between measured and actual values in the 3D reconstruction images, all of them were enlarged. The VRT method displayed the smallest enlargement. On the other hand, the sagittal images that were obtained using the MPR method displayed an average difference of about 5.32 mm in transverse length and an average transverse length of about 2.72 mm. In conclusion, the reconstruction technique that produced an aneurysm size similar to the actual size was the VRT, and the reconstruction of the aneurysm using the VRT could be performed three-dimensionally and compared with other techniques. Therefore, observation of the anatomical site is excellent. In addition, the size determined from the enlargement of the reconstructed image was similar to the actual size; therefore, it can be helpful for establishing an effective treatment plan.

CT cholangiography in dogs with gallbladder mucocoele.

To summarise CT cholangiography findings in dogs with gallbladder mucocoele. Each of 10 dogs with gallbladder mucocoele underwent CT cholangiography using meglumine iotroxate before cholecystectomy. The following structures of the biliary system were evaluated: the right and left hepatic ducts, common hepatic duct, cystic duct, common bile duct and gallbladder. The hepatic duct, cystic duct, common bile duct and gallbladder were imaged by contrast-enhanced CT cholangiography. The passage of the contrast medium through the bile duct into the duodenum was visible in nine dogs. The curved planar reformation images of two dogs showed they had filling defects in the bile duct system. In one dog with hyperbilirubinaemia due to chronic hepatitis, the bile duct system was not completely contrast-enhanced. Surgical exploration revealed no evidence of common bile duct obstruction in any dog. CT cholangiography delineates the structural characteristics of the biliary system and partially estimates its patency in dogs with gallbladder mucocoele. Therefore this procedure may be useful as a preoperative screen of the bile duct system in dogs with gallbladder mucocoele.

Role of MDCT renal angiography in determining the anatomical eligibility for renal sympathetic denervation in resistant hypertensive patients

ObjectiveAim of this study was to assess role of Multidetector computed tomography (MDCT) Renal Angiography in determining the anatomical eligibility for renal sympathetic denervation in resistant hypertensive patients. Subjects and methodsThis study included 30 patients, referred from hypertension unit in Zagazig University Hospital, with refractory systemic hypertension [an office blood pressure (BP) >140/90 mmHg despite treatment with at least three drugs, including a diuretic in adequate doses]. All cases were performed using a 128-slice MDCT scanner. All data were transferred to an imaging workstation for reconstruction and analysis. Axial source images were post-processed to produce multiplanar reformation, curved planar reformation, maximum intensity projection and volume rendering images. ResultsMost patients (46.7%) had an A1/A1 type renal artery (RA). 66.7% were completely eligible (CE), 23.3% were partially eligible (PE), and 10% were non eligible (NE). Regarding intraobserver agreement; concordance between two readings by the same radiologist was in 96.7%, while discordance was in 3.3%. Regarding interobserver agreement; concordance between two radiologists was in 93.3% while discordance was in 6.7%. ConclusionMDCT renal angiography gives valuable knowledge to the interventional radiologist and cardiologist before renal artery denervation (RDN) to increase the success rate.

Prediction of pancreatic cancer surgical outcomes and prognosis based on an objective resectability scoring system.

446 Background: There is no consensus on the best radiographic criteria to define pancreatic cancer (PCA) resectability. We undertook this study to objectively assess the probability of tumor resection based on quantitative measures of tumor abutment from the main peripancreatic vessels. Methods: Measurements of the circumferential degree and length of solid tumor contact with the superior mesenteric artery, the celiac artery/common hepatic artery, and superior mesenteric vein/portal vein were obtained through curved planar reformations from diagnostic CT images of PCA patients treated at our institution between 2001 and 2015. Results: A total of 399 patients were identified, of which 294 were used for the analysis. Of them, 113 (38.4%) were resected, 71 (62.8%) with negative margins (R0). Based on the individual measurements of vascular involvement, a resectability scoring system (RSS) was created (table), and used in a classification and regression tree model that correlated strongly with resection (p &lt; 0.0001) and R0 resection (p &lt; 0.0001) probabilities. The RSS demonstrated a higher PPV, NPV and accuracy (94.3%; 98.6%; 97%) to predict resection compared to the NCCN (90.8%; 96.7%; 94.5%) and MDACC resectability criteria (87.1%; 97.9%; 93.5%). Moreover, the RSS correlated with overall survival (OS) (p &lt; 0.0001) and metastasis-free survival (p &lt; 0.0001). Conclusions: We developed a PCA resectability scoring system that is objective, reproducible, and highly correlated with surgical outcomes and prognosis. External validation is warranted. [Table: see text]

Curved Planar Reformation for the Evaluation of Hydromyelia in Patients With Scoliosis Associated With Spinal Dysraphism.

A retrospective cohort study. Scoliosis and hydromyelia have frequently been observed in patients with spinal dysraphism. We investigated the applicability of curved planar reformation (CPR) for evaluating hydromyelia in patients with scoliosis associated with spinal dysraphism. It is quite difficult to evaluate scoliosis and hydromyelia in patients with spinal dysraphism. We identified 11 patients with scoliosis and a Cobb angle of >20° among 107 spinal dysraphism patients. In addition to routine T1- and T2-weighted axial and sagittal MRI, we obtained three-dimensional constructive interference in steady-state magnetic resonance imaging (MRI) as sagittal cross-section volume images. The spinal cord and hydromyelia were rendered into a single-plane, two-dimensional image using the straightened CPR technique. In cases of scoliosis with hydromyelia, the sagittal length and maximal diameters of hydromyelia and the spinal cord were measured by three examiners. Measurement errors among examiners were evaluated using standard deviation (SD) and coefficient of variation (CV). Each series of image sets provided a straightened CPR image that clearly delineated the entire length of the linearized spinal cord in a single plane. The straightened CPR image also demonstrated the accurate lengths and estimated volume of hydromyelia. Given that three of the 11 patients underwent serial MRI during this period, we were able to accurately compare volume changes. In the sagittal length of the hydromyelia, SD and CV were smaller with the straightened CPR technique than with the conventional T2 WI sagittal section in all cases, showing a statistically significant difference between both techniques (SD: P = 0.014, CV: P = 0.013). Even in the measurements, the difference in CV between both techniques was close to statistical significance. The straightened CPR technique is useful for accurately identifying volume changes in hydromyelia, even in patients with severe scoliosis. 1.

Semiautomatic Volumetry of Low Attenuation of Thoracic Aortic Plaques on Curved Planar Reformations Using MDCT Angiographic Data with 0.5 mm Collimation.

To evaluate the relationship of aortic low attenuation plaque volume (LAPV) on multidetector computed tomography (MDCT) with the abdominal aortic aneurysm (AAA), the coronary arterial disease (CAD, ≥50% stenosis), severe (≥90% stenosis) CAD, hypertension, and long-term (≥10 years) hypertension. Curved planar reformations (CPR) of three segments (the ascending, the arch, and the upper descending aorta) of the thoracic aorta were generated with attenuation-dependent color codes to measure LAPV with 0~29 HU and total noncalcified plaque volume (TNPV) with 0~150 HU in 95 patients. Correlation coefficients were employed to assess the impact of each LAPV and TNPV on AAA, CAD, severe CAD, hypertension, and long-term hypertension. Each Mean LAPV/cm and TNPV/cm was statistically greater in the aortic arch than the ascending (p < 0.001 on each) or the proximal descending segment (p < 0.001 on each). LAPV in the aortic arch has moderate correlations with AAA, severe CAD, and long-term hypertension (r = 0.643, 0.639, 0.662, resp.). Plaque volumes in each aortic segment can be measured clinically and the increasing LAPV in the arch may be a significant factor associated with the development of severe atherosclerosis underlying AAA, severe CAD, and long-term hypertension.

Semi-Supervised Cerebrovascular Segmentation by Hierarchical Convolutional Neural Network

Due to the tortuosity and the complexity of cerebral vasculature and the similar intensity distribution with the background, it remains challenging to accurately segment cerebral vessels from magnetic resonance angiography (MRA). The previous rule-based methods have limitations when applied to accurate clinical diagnosis, such as the under-segmentation on complex vessels, the dependence on domain knowledge, and the lack of quantification estimation. In this paper, we proposed a semi-supervised cerebrovascular segmentation method with a hierarchical convolutional neural network (H-CNN) that transfers the exquisite model/feature design in rule-based methods to solve the mapping from MRA images to cerebral vessels. First, we generated the tube-level labels of cerebral vessels with centerlines and estimated radii. Second, we constructed and trained an H-CNN with the MRA images and corresponding tube-level labels. Third, the stopping criterion of the proposed H-CNN was determined by the comprehensive index (CI) that was defined based on partially annotated voxel-level ground truth. The comparison of our H-CNN with the vesselness, bi-Gaussian, optimally oriented flux, vessel enhancing diffusion, hybrid diffusion with continuous switch, Mimics software, convolutional neutral network2D (CNN)2D, and CNN3D were conducted on six testing images. The mean sensitivity, accuracy, and the CI of our H-CNN are 94.69%, 97.85%, and 2.99%, respectively, outperforming the other methods. The curved planar reformation also visualized the performance of H-CNN for cerebrovascular segmentation. Given only the tube-level labels, the proposed H-CNN method accomplished the voxel-level vessel segmentation via the hierarchical update of CNN. The H-CNN can potentially to be applied for the accurate diagnosis of cerebrovascular diseases and other medical image segmentation with only partially correct labels.

Semi-Automated Extraction of Crohns Disease MR Imaging Markers using a 3D Residual CNN with Distance Prior.

We propose a 3D residual convolutional neural network (CNN) algorithm with an integrated distance prior for segmenting the small bowel lumen and wall to enable extraction of pediatric Crohns disease (pCD) imaging markers from T1-weighted contrast-enhanced MR images. Our proposed segmentation framework enables, for the first time, to quantitatively assess luminal narrowing and dilation in CD aimed at optimizing surgical decisions as well as analyzing bowel wall thickness and tissue enhancement for assessment of response to therapy. Given seed points along the bowel lumen, the proposed algorithm automatically extracts 3D image patches centered on these points and a distance map from the interpolated centerline. These 3D patches and corresponding distance map are jointly used by the proposed residual CNN architecture to segment the lumen and the wall, and to extract imaging markers. Due to lack of available training data, we also propose a novel and efficient semi-automated segmentation algorithm based on graph-cuts technique as well as a software tool for quickly editing labeled data that was used to train our proposed CNN model. The method which is based on curved planar reformation of the small bowel is also useful for visualizing, manually refining, and measuring pCD imaging markers. In preliminary experiments, our CNN network obtained Dice coefficients of 75 ± 18%, 81 ± 8% and 97 ± 2% for the lumen, wall and background, respectively.

Multipath Curved Planar Reformations of Peripheral CT Angiography: Diagnostic Accuracy and Time Efficiency

ObjectivesTo compare diagnostic performance and time efficiency between 3D multipath curved planar reformations (mpCPRs) and axial images of CT angiography for the pre-interventional assessment of peripheral arterial disease (PAD), with digital subtraction angiography as the standard of reference.MethodsForty patients (10 females, mean age 72 years), referred to CTA prior to endovascular treatment of PAD, were prospectively included and underwent peripheral CT angiography. A semiautomated toolbox was used to render mpCPRs. Twenty-one arterial segments were defined in each leg; for each segment, the presence of stenosis > 70% was assessed on mpCPRs and axial images by two readers, independently, with digital subtraction angiography as gold standard.ResultsBoth readers reached lower sensitivity (Reader 1: 91 vs. 94%, p = 0.08; Reader 2: 89 vs. 93%, p = 0.03) but significantly higher specificity (Reader 1: 94 vs. 89%, p < 0.01; Reader 2: 96 vs. 95%, p = 0.01) with mpCPRs than with axial images. Reader 1 achieved significantly higher accuracy with mpCPRs (93 vs. 91%, p = 0.02), and Reader 2 had similar overall accuracy in both evaluations (94 vs. 94%, p = 0.96). Both readers read mpCPRs significantly faster than axial images (Reader 1: 5′45″ based on mpCPRs vs. 7′40″ based on axial images; Reader 2: 4′41″ based on mpCPRs vs. 6′57″ based on axial images; p < 0.01).ConclusionsmpCPRs are a promising 3D reformation technique that facilitates a fast assessment of PAD with high diagnostic accuracy.

Research on gradual change of ascending aorta diameter

Objective To study the changes in the diameter of the ascending aorta at different levels. Methods A total of 287 patients were enrolled in this study from November 2016 to January 2017 at the Chinese People′s Liberation Army General Hospital in Beijing. Each patient had undergone enhanced computerized tomography scanning, and the systolic and diastolic images were reconstructed for each patient. Ten times distance accounts for percentage was calculated per 10% unit of ascending aorta. The maximal diameters of each level were measured by 3 mensio Vascular 8.1 software with curved planar reformation. Generalized additive mixed model with smoothing function and threshold saturation effect analysis with generalized estimating equations were used to analysis the changing regularity of ascending aortic diameters and its consistency using stratified analysis. Furthermore, stratified analyses were conducted aauording to sex, age, BMI, smoking status and history of chronic diseases. Results A nonlinear relationship between the maximal diameters and distance was observed. With the increase of distance, the maximal diameters of ascending aorta presented an inverted U shape. In the first half, the ascending aortic maximal diameter increased 1.16 mm while the distance increased ten percent of the ascending aortic length (P<0.001). In the second half, the ascending aortic maximal diameter reduced 0.47 mm while the distance increased ten percent of the ascending aortic length (P<0.001). The results showed that the changing regularity of ascending aortic diameter has no significant difference between systolic and diastolic periods. Conclusions With the increase of distance, the maximal diameters of ascending aorta increase and then decrease. The regularity of ascending aortic diameter between systole and diastole is consistent. In each subgroup, the regularity of ascending aortic diameter is not completely consistent, but the difference has not clinical significance. Key words: Aorta; Blood vessels; Periodicity, heart; Computer tomography

Quantitative assessment on coronary computed tomography angiography (CCTA) image quality: comparisons between genders and different tube voltage settings.

This study was carried out to quantify and compare the quantitative image quality of coronary computed tomography angiography (CCTA) between genders as well as between different tube voltages scan protocols. Fifty-five cases of CCTA were collected retrospectively and all images including reformatted axial images at systolic and diastolic phases as well as images with curved multi planar reformation (cMPR) were obtained. Quantitative image quality including signal intensity, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of right coronary artery (RCA), left anterior descending artery (LAD), left circumflex artery (LCx) and left main artery (LM) were quantified using Analyze 12.0 software. Six hundred and fifty-seven coronary arteries were evaluated. There were no significant differences in any quantitative image quality parameters between genders. 100 kilovoltage peak (kVp) scanning protocol produced images with significantly higher signal intensity compared to 120 kVp scanning protocol (P<0.001) in all coronary arteries in all types of images. Higher SNR was also observed in 100 kVp scan protocol in all coronary arteries except in LCx where 120 kVp showed better SNR than 100 kVp. There were no significant differences in image quality of CCTA between genders and different tube voltages. Lower tube voltage (100 kVp) scanning protocol is recommended in clinical practice to reduce the radiation dose to patient.

Coronary artery analysis: Computer-assisted selection of best-quality segments in multiple-phase coronary CT angiography.

The authors are developing an automated method to identify the best-quality coronary arterial segment from multiple-phase coronary CT angiography (cCTA) acquisitions, which may be used by either interpreting physicians or computer-aided detection systems to optimally and efficiently utilize the diagnostic information available in multiple-phase cCTA for the detection of coronary artery disease. After initialization with a manually identified seed point, each coronary artery tree is automatically extracted from multiple cCTA phases using our multiscale coronary artery response enhancement and 3D rolling balloon region growing vessel segmentation and tracking method. The coronary artery trees from multiple phases are then aligned by a global registration using an affine transformation with quadratic terms and nonlinear simplex optimization, followed by a local registration using a cubic B-spline method with fast localized optimization. The corresponding coronary arteries among the available phases are identified using a recursive coronary segment matching method. Each of the identified vessel segments is transformed by the curved planar reformation (CPR) method. Four features are extracted from each corresponding segment as quality indicators in the original computed tomography volume and the straightened CPR volume, and each quality indicator is used as a voting classifier for the arterial segment. A weighted voting ensemble (WVE) classifier is designed to combine the votes of the four voting classifiers for each corresponding segment. The segment with the highest WVE vote is then selected as the best-quality segment. In this study, the training and test sets consisted of 6 and 20 cCTA cases, respectively, each with 6 phases, containing a total of 156 cCTA volumes and 312 coronary artery trees. An observer preference study was also conducted with one expert cardiothoracic radiologist and four nonradiologist readers to visually rank vessel segment quality. The performance of our automated method was evaluated by comparing the automatically identified best-quality segments identified by the computer to those selected by the observers. For the 20 test cases, 254 groups of corresponding vessel segments were identified after multiple phase registration and recursive matching. The AI-BQ segments agreed with the radiologist's top 2 ranked segments in 78.3% of the 254 groups (Cohen's kappa 0.60), and with the 4 nonradiologist observers in 76.8%, 84.3%, 83.9%, and 85.8% of the 254 groups. In addition, 89.4% of the AI-BQ segments agreed with at least two observers' top 2 rankings, and 96.5% agreed with at least one observer's top 2 rankings. In comparison, agreement between the four observers' top ranked segment and the radiologist's top 2 ranked segments were 79.9%, 80.7%, 82.3%, and 76.8%, respectively, with kappa values ranging from 0.56 to 0.68. The performance of our automated method for selecting the best-quality coronary segments from a multiple-phase cCTA acquisition was comparable to the selection made by human observers. This study demonstrates the potential usefulness of the automated method in clinical practice, enabling interpreting physicians to fully utilize the best available information in cCTA for diagnosis of coronary disease, without requiring manual search through the multiple phases and minimizing the variability in image phase selection for evaluation of coronary artery segments across the diversity of human readers with variations in expertise.

Graft Bending Angle at the Intra-articular Femoral Tunnel Aperture After Single-Bundle Posterior Cruciate Ligament Reconstruction

Background: To date, no in vivo 3-dimensional computed tomography (3D-CT) studies have compared graft bending angles at the femoral tunnel aperture and femoral tunnel length in patients who underwent posterior cruciate ligament (PCL) reconstruction with outside-in (OI) and inside-out (IO) techniques. Purpose/Hypothesis: This study used in vivo 3D-CT analysis to compare graft bending angles at the femoral tunnel aperture and femoral tunnel lengths after OI and IO femoral drilling techniques in single-bundle PCL reconstruction. It was hypothesized that the graft bending angle at the femoral tunnel aperture would be less acute with the OI compared with the IO technique, with no difference in femoral tunnel lengths. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Immediate postoperative in vivo 3D-CT and curved planar reformation were used to assess the graft bending angles and femoral tunnel lengths in the sagittal, axial, and coronal planes in 67 patients who underwent single-bundle PCL reconstruction with the OI (n = 37) and IO (n = 30) techniques. Results: The mean graft bending angles on the sagittal and axial planes were 8.2° more acute (23.5° vs 15.3°, P = .011) and 5.3° more acute (49.0° vs 43.7°, P = .013), respectively, with the IO compared with the OI technique, but the difference in the coronal plane was not statistically significant (25.3° vs 24.8°, P = .623). Femoral tunnel length was similar in the 2 groups. Conclusion: The graft bending angles in single-bundle PCL reconstruction were more acute in the sagittal and axial planes with the IO compared with the OI technique, but there was no difference in the coronal plane. In addition, femoral tunnel lengths did not differ significantly in patients who underwent OI and IO single-bundle PCL reconstructions. Although further biomechanical studies are needed to evaluate the effect on graft failure of a <10° difference in graft bending angle, the small magnitude of this difference would likely have little adverse effect on graft survival.

New hybrid reformations of peripheral CT angiography: do we still need axial images?

PurposeTo quantify the detectability of peripheral artery stenosis on hybrid CT angiography (CTA) reformations. MethodsHybrid reformations were developed by combining multipath curved planar reformations (mpCPR) and maximum intensity projections (MIP). Fifty peripheral CTAs were evaluated twice: either with MIP, mpCPR and axial images or with hybrid reformations only. Digital subtraction angiography served as gold standard. ResultsUsing hybrid reformations, two independent readers detected 88.0% and 81.3% of significant stenosis, respectively. However, CTA including axial images detected statistically significant more lesions (98%). ConclusionPeripheral CTA reading including axial images is still recommended. Further improvement of these hybrid reformations is necessary.

ADR--Anatomy-Driven Reformation.

Dedicated visualization methods are among the most important tools of modern computer-aided medical applications. Reformation methods such as Multiplanar Reformation or Curved Planar Reformation have evolved as useful tools that facilitate diagnostic and therapeutic work. In this paper, we present a novel approach that can be seen as a generalization of Multiplanar Reformation to curved surfaces. The main concept is to generate reformatted medical volumes driven by the individual anatomical geometry of a specific patient. This process generates flat views of anatomical structures that facilitate many tasks such as diagnosis, navigation and annotation. Our reformation framework is based on a non-linear as-rigid-as-possible volumetric deformation scheme that uses generic triangular surface meshes as input. To manage inevitable distortions during reformation, we introduce importance maps which allow controlling the error distribution and improving the overall visual quality in areas of elevated interest. Our method seamlessly integrates with well-established concepts such as the slice-based inspection of medical datasets and we believe it can improve the overall efficiency of many medical workflows. To demonstrate this, we additionally present an integrated visualization system and discuss several use cases that substantiate its benefits.