To date, 3D spine reconstruction from biplanar radiographs involves intensive user supervision and semi-automated methods that are time-consuming and not effective in clinical routine. This paper ...proposes a new, fast, and automated 3D spine reconstruction method through which a realistic statistical shape model of the spine is fitted to images using convolutional neural networks (CNN). The CNNs automatically detect the anatomical landmarks controlling the spine model deformation through a hierarchical and gradual iterative process. The performance assessment used a set of 68 biplanar radiographs, composed of both asymptomatic subjects and adolescent idiopathic scoliosis patients, in order to compare automated reconstructions with ground truths build using multiple experts-supervised reconstructions. The mean (SD) errors of landmark locations (3D Euclidean distances) were 1.6 (1.3) mm, 1.8 (1.3) mm, and 2.3 (1.4) mm for the vertebral body center, endplate centers, and pedicle centers, respectively. The clinical parameters extracted from the automated 3D reconstruction (reconstruction time is less than one minute) presented an absolute mean error between 2.8° and 4.7° for the main spinal parameters and between 1° and 2.1° for pelvic parameters. Automated and expert's agreement analysis reported that, on average, 89% of automated measurements were inside the expert's confidence intervals. The proposed automated 3D spine reconstruction method provides an important step that should help the dissemination and adoption of 3D measurements in clinical routine.
The robustness and accuracy of the intensity-based 3D/2D registration of a 3D model on planar X-ray image(s) is related to the quality of the image correspondences between the digitally reconstructed ...radiographs (DRR) generated from the 3D models (varying image) and the X-ray images (fixed target). While much effort may be devoted to generating realistic DRR that are similar to real X-rays (using complex X-ray simulation, adding densities information in 3D models, etc.), significant differences still remain between DRR and real X-ray images. Differences such as the presence of adjacent or superimposed soft tissue and bony or foreign structures lead to image matching difficulties and decrease the 3D/2D registration performance. In the proposed method, the X-ray images were converted into DRR images using a GAN-based cross-modality image-to-images translation. With this added prior step of XRAY-to-DRR translation, standard similarity measures become efficient even when using simple and fast DRR projection. For both images to match, they must belong to the same image domain and essentially contain the same kind of information. The XRAY-to-DRR translation also addresses the well-known issue of registering an object in a scene composed of multiple objects by separating the superimposed or/and adjacent objects to avoid mismatching across similar structures. We applied the proposed method to the 3D/2D fine registration of vertebra deformable models to biplanar radiographs of the spine. We showed that the XRAY-to-DRR translation enhances the registration results, by increasing the capture range and decreasing dependence on the similarity measure choice since the multi-modal registration becomes mono-modal.
After 5 y of collecting data on diagnostic reference levels (DRLs), the Nuclear Safety and Radiation Protection French Institute (IRSN) presents the analyses of this data. The analyses of the ...collected data for radiology, computed tomography (CT) and nuclear medicine allow IRSN to estimate the level of regulatory application by health professionals and the representativeness of current DRL in terms of relevant examinations, dosimetric quantities, numerical values and patient morphologies. Since 2004, the involvement of professionals has highly increased, especially in nuclear medicine, followed by CT and then by radiology. Analyses show some discordance between regulatory examinations and clinical practice. Some of the dosimetric quantities used for the DRL setting are insufficient or not relevant enough, and some numerical values should also be reviewed. On the basis of these findings, IRSN formulates recommendations to update regulatory DRL with current and relevant examination lists, dosimetric quantities and numerical values.
Abstract Reconstruction methods from biplanar X-rays provide 3D analysis of spinal deformities for patients in standing position with a low radiation dose. However, such methods require an important ...reconstruction time and there is a clinical need for fast and accurate techniques. This study proposes and evaluates a novel reconstruction method of the spine from biplanar X-rays. The approach uses parametric models based on longitudinal and transversal inferences. A first reconstruction level, dedicated to routine clinical use, allows to get a fast estimate (reconstruction time: 2 min 30 s) of the 3D reconstruction and accurate clinical measurements. The clinical measurements precision (evaluated on asymptomatic subjects, moderate and severe scolioses) was between 1.2° and 5.6°. For a more accurate 3D reconstruction (complex pathologies or research purposes), a second reconstruction level can be obtained within a reduced reconstruction time (10 min) with a fine adjustment of the 3D models. The mean shape accuracy in comparison with CT-scan was 1.0 mm. The 3D reconstruction method precision was 1.8 mm for the vertebrae position and between 2.3° and 3.9° for the orientation. With a reduced reconstruction time, an improved accuracy and precision and a method proposing two reconstruction levels, this approach is efficient for both clinical routine uses and research purposes.
Cross-sectional analysis of longitudinal anatomical magnetic resonance imaging (MRI) data may be suboptimal as each dataset is analyzed independently. In this study, we evaluate how much variability ...can be reduced by analyzing structural volume changes in longitudinal data using longitudinal analysis. We propose a two-part pipeline that consists of longitudinal registration and longitudinal classification. The longitudinal registration step includes the creation of subject-specific linear and nonlinear templates that are then registered to a population template. The longitudinal classification step comprises a four-dimensional expectation-maximization algorithm, using a priori classes computed by averaging the tissue classes of all time points obtained cross-sectionally.
To study the impact of these two steps, we apply the framework completely (“LL method”: Longitudinal registration and Longitudinal classification) and partially (“LC method”: Longitudinal registration and Cross-sectional classification) and compare these with a standard cross-sectional framework (“CC method”: Cross-sectional registration and Cross-sectional classification).
The three methods are applied to (1) a scan–rescan database to analyze reliability and (2) the NIH pediatric population to compare gray matter growth trajectories evaluated with a linear mixed model.
The LL method, and the LC method to a lesser extent, significantly reduced the variability in the measurements in the scan–rescan study and gave the best-fitted gray matter growth model with the NIH pediatric MRI database. The results confirm that both steps of the longitudinal framework reduce variability and improve accuracy in comparison with the cross-sectional framework, with longitudinal classification yielding the greatest impact.
Using the improved method to analyze longitudinal data, we study the growth trajectories of anatomical brain structures in childhood using the NIH pediatric MRI database. We report age- and gender-related growth trajectories of specific regions of the brain during childhood that could be used as a reference in studying the impact of neurological disorders on brain development.
•We propose a new longitudinal method to analyze longitudinal brain MRI datasets.•The method includes longitudinal registration and longitudinal classification steps.•We compare this method with cross-sectional methods.•A scan–rescan study shows that both longitudinal steps reduce variability.•The new method gives the best-fitted GM growth model using the NIH pediatric data.
In clinical routine, lower limb analysis relies on conventional X-ray (2D view) or computerised tomography (CT) Scan (lying position). However, these methods do not allow 3D analysis in standing ...position. The aim of this study is to propose a fast and accurate 3D-reconstruction-method based on parametric models and statistical inferences from biplanar X-rays with clinical measurements' (CM) assessment in standing position for a clinical routine use. For the reproducibility study, the 95% CI was under 2.7° for all lower limbs' angular measurements except for tibial torsion, femoral torsion and tibiofemoral rotation ( < 5°). The 95% CI were under 2.5 mm for lower limbs' lengths and 1.5 to 3° for the pelvis' CM. Comparisons between X-rays and CT-scan based 3D shapes in vitro showed mean differences of 1.0 mm (95% CI = 2.4 mm). Comparisons of 2D lower limbs' and 3D pelvis' CM between standing 'Shifted-Feet' and 'Non-Shifted-Feet' position showed means differences of 0.0 to 1.4°. Significant differences were found only for pelvic obliquity and rotation. The reconstruction time was about 5 min.
Background
Mastectomy with immediate breast reconstruction (IBR) is a surgical strategy in breast cancer when breast‐conserving surgery is not an option. There is a lack of evidence showing an ...advantage of mastectomy plus IBR over mastectomy alone on health‐related quality of life (QoL).
Methods
A large prospective multicentre survey, STIC‐RMI (support of innovative and expensive techniques – immediate breast reconstruction), was undertaken to study the changes in QoL in patients treated by mastectomy with or without IBR. Patients were recruited between 2007 and 2009. European Organisation for Research and Treatment of Cancer QLQ‐C30 and QLQ‐BR23 instruments were used to assess QoL before operation, and at 6 and 12 months after surgery. A propensity score was used to compare QoL between mastectomy alone and mastectomy plus IBR, with limited bias.
Results
A total of 595 patients were included from 22 French academic hospitals, of whom 407 (68·4 per cent) underwent IBR. One‐year data were available for 71·1 per cent of patients. Factors associated with IBR were age, histological tumour type, palpable nodes and an attempt at breast‐conserving surgery. At inclusion, QoL was significantly better in the IBR group (P < 0·001) and there was no significant change in either group during 1 year compared with baseline. Results for the QLQ‐BR23 functional dimension varied according to propensity score quartiles; IBR had no influence in the lowest quartile. In the upper quartiles, QoL increased slightly over the year among patients who had IBR, whereas it decreased among those who had mastectomy alone (P = 0·037). Satisfaction with the cosmetic outcome strongly influenced QoL, especially in upper quartiles (P < 0·001). However, an unsatisfactory outcome after IBR was still considered a better condition than simple mastectomy.
Conclusion
The QoL benefit provided by IBR depends on patients' life status at inclusion; young active women with an in situ tumour are more likely to preserve their QoL after IBR.
Good for the appropriate patient
Sinking of particles is a key mechanism in the transport of organic matter from the ocean’s productive surface layer to the deep sea and sediments, but also constitutes a loss of carbon and ...growth-limiting nutrients to the pelagic food web. Knowledge on export of particulate phosphorus is limited, particularly in high-latitude regions, in spite of its role as a co-limiting factor in many marine systems. We therefore investigated suspended concentrations and vertical export (by means of sediment traps) of particulate organic carbon (POC), nitrogen (PON) and total particulate phosphorus (TPP) at 3 contrasting sites in the Fram Strait and Barents Sea opening and quantified the contribution of zooplankton faecal pellets to POC, PON and TPP export. The TPP fluxes are the first to be reported from this region and probably the first from the entire Arctic Ocean. The suspended and exported C:N ratios were close to the Redfield ratio and did not differ significantly from each other (mean atomic ratios of 6.1 and 6.3, respectively). The mean C:P of suspended particles (91) was below Redfield, whereas the exported mean (117) exceeded Redfield, indicating more efficient retention of phosphorus than of nitrogen in the water column. Copepod faecal pellets had low C:P ratios and contributed a higher proportion to phosphorus export (mean of 17%) than to carbon and nitrogen export (10%). Faecal pellets may therefore be an important loss factor for phosphorus from the water column compared to slower-sinking material, which is retained more efficiently.
Abstract Objectives Complete surgery with no macroscopic residual disease (RD) at primary (PDS) or interval debulking surgery (IDS) is the main objective of surgery in advanced epithelial ovarian ...cancer (EOC). The aim of this work was to evaluate the impact on survival of the number of neoadjuvant chemotherapy (NAC) cycles before IDS in EOC patients. Methods Data from EOC patients (stages IIIC–IV), operated on between 1995 and 2010 were consecutively recorded. NAC/IDS patients were analyzed according to the number of preoperative cycles (< 4 = group B1; > 4 = group B2) and compared with patients receiving PDS (group A). Patients with complete resection were specifically analyzed. Results 367 patients were analyzed, 220 received PDS and 147 had IDS/NAC. In group B, 37 patients received more than 4 NAC cycles (group B2). Group B2 patients presented more frequently stage IV disease at diagnosis (p < 0.01) compared to groups A and B1. The rate of complete cytoreduction was higher in group B (p < 0.001). Patients with no RD after IDS and who had received more than 4 NAC cycles had poor survival (p < 0.001) despite complete removal of their tumor (relative risk of death after multivariate analysis of 3 (p < 0.001)) with an independent impact from disease stage and WHO performance status. Conclusions Patients with advanced EOC receiving complete IDS after more than 4 cycles of NAC have poor prognosis. Despite worse prognostic factors observed in this group of patients, our study reinforces the concept of early and complete removal of all macroscopic tumors in the therapeutic sequence of EOC.
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