Vojtěch Kulvait's research while affiliated with Helmholtz-Zentrum Hereon and other places

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Publications (16)

Liver segmentation using Turbolift learning for CT and cone-beam C-arm perfusion imaging
Article
  • Mar 2023
Model-based reconstruction employing the time separation technique (TST) was found to improve dynamic perfusion imaging of the liver using C-arm cone-beam computed tomography (CBCT). To apply TST using prior knowledge extracted from CT perfusion data, the liver should be accurately segmented from the CT scans. Reconstructions of primary and model-b...
Figure 8: Dice scores for 6-fold cross-validation -comparing the...
Quantitative estimation of the segmentation performances of slices with...
Liver Segmentation using Turbolift Learning for CT and Cone-beam C-arm Perfusion Imaging
Preprint
Full-text available
  • Jul 2022
Model-based reconstruction employing the time separation technique (TST) was found to improve dynamic perfusion imaging of the liver using C-arm cone-beam computed tomography (CBCT). To apply TST using prior knowledge extracted from CT perfusion data, the liver should be accurately segmented from the CT scans. Reconstructions of primary and model-b...
Time Separation Technique Using Prior Knowledge for Dynamic Liver Perfusion Imaging
Conference Paper
Full-text available
  • Jun 2022
The perfusion imaging using C-arm CT could be used intraoperatively for liver cancer treatment planning and evaluation. To deal with undersampled data due to slow C-arm CT rotation and pause between the rotations, we applied model-based reconstruction methods. Recent works using the time separation technique with an analytical basis function set ha...
A novel use of time separation technique to improve flat detector CT perfusion imaging in stroke patients
Article
  • Apr 2022
Background: CT perfusion imaging (CTP) is used in the diagnostic workup of acute ischemic stroke (AIS). CTP may be performed within the angio suite using flat detector CT (FDCT) to help reduce patient management time. Purpose: In order to significantly improve FDCT perfusion (FDCTP) imaging, data processing algorithms need to be able to compensa...
Perarson correlation coefficients comparing data without dimension...
Noise and dose reduction in CT brain perfusion acquisition by projecting time attenuation curves onto lower dimensional spaces
Preprint
Full-text available
  • Nov 2021
CT perfusion imaging (CTP) plays an important role in decision making for the treatment of acute ischemic stroke with large vessel occlusion. Since the CT perfusion scan time is approximately one minute, the patient is exposed to a non-negligible dose of ionizing radiation. However, further dose reduction increases the level of noise in the data an...
BF measurements in units of mL/100g/ min. Mean and the standard...
Application of Time Separation Technique to Enhance C-arm CT Dynamic Liver Perfusion Imaging
Preprint
Full-text available
  • Oct 2021
Perfusion imaging is an interesting new modality for evaluation and assessment of the liver cancer treatment. C-Arm CT provides a possibility to perform perfusion imaging scans intra-operatively for even faster evaluation. The slow speed of the C-Arm CT rotation and the presence of the noise, however, have an impact on the reconstruction and theref...
Software Implementation of the Krylov Methods Based Reconstruction for the 3D Cone Beam CT Operator
Preprint
Full-text available
  • Oct 2021
Krylov subspace methods are considered a standard tool to solve large systems of linear algebraic equations in many scientific disciplines such as image restoration or solving partial differential equations in mechanics of continuum. In the context of computer tomography however, the mostly used algebraic reconstruction techniques are based on clas...
Fig. 1. Cutting voxel projector estimates detected extinction at...
Fig. 2. Auxiliary local Euclidean coordinates for a given view that...
Cutting Voxel Projector a New Approach to Construct 3D Cone Beam CT Operator
Preprint
Full-text available
  • Oct 2021
In this paper, we introduce a new class of projectors for 3D cone beam tomographic reconstruction. We find analytical formulas for the relationship between the voxel volume projected onto a given detector pixel and its contribution to the extinction value detected on that pixel. Using this approach, we construct a near-exact projector and backproje...
Figure 1: FDCTP reprojected data, a single view of the 212-th angle of...
Figure 2: Patient 1A. AIF derived from spline interpolation of CTP data...
Figure 3: Perfusion parameters patient 1A, z = 15. A: ground truth CTP...
Time separation technique with the basis of trigonometric functions as an efficient method for flat detector CT brain perfusion imaging
Preprint
Full-text available
  • Oct 2021
Dynamic perfusion imaging is routinely used in the diagnostic workup of acute ischemic stroke (AIS). At present, perfusion imaging can also be performed within the angio suite using flat detector computed tomography (FDCT). However, higher noise level, slower rotation speed and lower frame rate need to be considered in FDCT perfusion (FDCTP) data p...
Optimierung der Organperfusion in einem präklinischen ex-vivo Lungenperfusionsmodell
Poster
Full-text available
  • Oct 2020
PRELIMINARY DATA Ex-vivo Lungenperfusions-Systeme (EVLP) erhalten das Organgewebe strukturell und funktionell außerhalb des Körpers. Neben der klinischen Anwendung in der Transplantationsmedizin werden EVLP-Systeme für translationale Forschungsansätze in der Lungenmedizin benötigt. Kommerziell erhältliche Système sind bei vielen experimentellen Ans...

Citations

... A simplified approach would be to reconstruct every rotation separately, the straightforward approach, which can result in over or underestimation of perfusion parameters (Haseljić et al., 2021). Recent publications have shown that model-based reconstruction and time separation technique (TST) could deal with poor temporal resolution (Montes and Lauritsch, 2009;Neukirchen et al., 2010;Manhart et al., 2013;Bannasch et al., 2018;Kulvait et al., 2022;Haseljić et al., 2021Haseljić et al., , 2022 and provide highly accurate liver perfusion maps. ...
Reference: Liver Segmentation using Turbolift Learning for CT and Cone-beam C-arm Perfusion Imaging
... For the brain reconstruction it is recommended to use either three or five basis functions since more could cause instabilities in projections, see [10], [11]. In [6] five trigonometric functions formed the analytical basis function set. ...
Reference: Time Separation Technique Using Prior Knowledge for Dynamic Liver Perfusion Imaging
... In this context, different CS-based techniques, such as sub-optimal convex relaxation methods 1 , greedy strategies 2 , and thresholding-based methods 3 , have been proposed in the literature. Nevertheless, their optimality proofs rely on very restrictive hypothesis such as the Restricted Isometry Properties conditions (RIP), which are computationally hard to be verified 4 7 for under-sampled image reconstruction. Within this scheme, there is no more need to integrate a regularization term into the reconstruction algorithm. ...
Reference: Nullspace-constrained modifications of under-sampled interventional CT images using instrument-specific prior information