Interobserver variability in the detection of cerebral venous thrombosis using CT venography with matched mask bone elimination

OBJECTIVES: Computed tomography venography (CTV) has proven to be a reliable imaging method in the evaluation of cerebral venous thrombosis with good correlation to magnetic resonance (MR) imaging and digital subtraction angiography (DSA). It is fast and widely accessible, especially in the emergency setting. For better visualization of vascular structures bone is often removed from the images. The purpose of this study was to evaluate the quality of a fully automatic bone removal method, matched mask bone elimination (MMBE), and to assess the interobserver variability of the CTV technique. PATIENTS AND METHODS: Fifty patients with clinical suspicion of cerebral venous thrombosis underwent multislice CTV with MMBE post-processing. Axial source images and maximum intensity projections were retrospectively evaluated by two neuroradiologists for quality of bone removal and for the presence or absence of thrombosis in nine dural sinuses and five deep cerebral veins. A per sinus/vein and a per patient analysis (thrombosis in at least one sinus or vein) was performed and interobserver agreement was assessed. RESULTS: Both observers considered bone removal good in all patients (100%). Interobserver agreement per patient was excellent (kappa=0.83), with a full agreement in 47 of 50 patients (94%). The interobserver agreement per sinus or vein was good (kappa=0.76), with a full agreement in 679 of 700 sinuses or veins (97%). CONCLUSION: CTV aided with MMBE is a robust technique for visualization of the intracranial venous circulation, removing bone effectively. CTV has high interobserver agreement for presence or absence of cerebral venous thrombosi

Patient-specific computational hemodynamics of intracranial aneurysms from 3D rotational angiography and CT angiography: an in vivo reproducibility study

Patient-specific simulations of the hemodynamics in intracranial aneurysms can be constructed by using image-based vascular models and CFD techniques. This work evaluates the impact of the choice of imaging technique on these simulationsThis work was partially supported by the @neurIST Integrated Project (cofinanced by the European Commission through contract no. IST-027703) and the CD-TEAM grant funded by the Spanish Ministry of Science and Innovation. Support from Philips Healthcare B.V. and ANSYS Europe Ltd is also acknowledged

Three-dimensional histologic validation of high-resolution SPECT of antibody distributions within xenografts

Longitudinal imaging of intratumoral distributions of antibodies in vivo in mouse cancer models is of great importance for developing cancer therapies. In this study, multipinhole SPECT with sub-half-millimeter resolution was tested for exploring intratumoral distributions of radiolabeled antibodies directed toward the epidermal growth factor receptor (EGFr) and compared with full 3-dimensional target expression assessed by immunohistochemistry. (111)In-labeled zalutumumab, a human monoclonal human EGFr-targeting antibody, was administered at a nonsaturating dose to 3 mice with xenografted A431 tumors exhibiting high EGFr expression. Total-body and focused in vivo tumor SPECT was performed at 0 and 48 h after injection and compared both visually and quantitatively with full 3-dimensional immunohistochemical staining for EGFr target expression. SPECT at 48 h after injection showed that activity was predominantly concentrated in the tumor (10.5% ± 1.3% of the total-body activity; average concentration, 30.1% ± 4.6% of the injected dose per cubic centimeter). (111)In-labeled EGFr-targeting antibodies were distributed heterogeneously throughout the tumor. Some hot spots were observed near the tumor rim. Immunohistochemistry indicated that the antibody distributions obtained by SPECT were morphologically similar to those obtained for ex vivo EGFr target expression. Regions showing low SPECT activity were necrotic or virtually negative for EGFr target expression. A good correlation (r = 0.86, P <0.0001) was found between the percentage of regions showing low activity on SPECT and the percentage of necrotic tissue on immunohistochemistry. Multipinhole SPECT enables high-resolution visualization and quantification of the heterogeneity of (111)In-zalutumumab concentrations in viv

Automated Segmentation of Cerebral Vasculature with Aneurysms in 3DRA and TOF-MRA using Geodesic Active Regions: an Evaluation Study

Purpose: To evaluate the suitability of an improved version of an automatic segmentation method based on geodesic active regions (GAR) for segmenting cerebral vasculature with aneurysms from 3D X-ray reconstruc-/ntion angiography (3DRA) and time of °ight magnetic resonance angiography (TOF-MRA) images available in the clinical routine./nMethods: Three aspects of the GAR method have been improved: execution time, robustness to variability in imaging protocols and robustness to variability in image spatial resolutions. The improved GAR was retrospectively evaluated on images from patients containing intracranial aneurysms in the area of the Circle of Willis and imaged with two modalities: 3DRA and TOF-MRA. Images were obtained from two clinical centers, each using di®erent imaging equipment. Evaluation included qualitative and quantitative analyses of/nthe segmentation results on 20 images from 10 patients. The gold standard was built from 660 cross-sections (33 per image) of vessels and aneurysms, manually measured by interventional neuroradiologists. GAR has also been compared to an interactive segmentation method: iso-intensity surface extraction (ISE). In addition, since patients had been imaged with the two modalities, we performed an inter-modality agreement analysis with respect to both the manual measurements and each of the two segmentation methods. Results: Both GAR and ISE di®ered from the gold standard within acceptable limits compared to the imaging resolution. GAR (ISE, respectively) had an average accuracy of 0.20 (0.24) mm for 3DRA and 0.27 (0.30) mm for TOF-MRA, and had a repeatability of 0.05 (0.20) mm. Compared to ISE, GAR had a lower qualitative error in the vessel region and a lower quantitative error in the aneurysm region. The repeatability/nof GAR was superior to manual measurements and ISE. The inter-modality agreement was similar between GAR and the manual measurements. Conclusions: The improved GAR method outperformed ISE qualitatively as well as quantitatively and is suitable for segmenting 3DRA and TOF-MRA images from clinical routine.The authors would like to acknowledge J. Schneiders for providing part of the TOF-MRA imaging data. The authors would like to thank also A. G. Radaelli, M. Nieber, and X. Planes for the help in implementing some of the methods. This work was partially supported by the @neurIST Integrated Project (co-financed by the European Commission through Contract No. IST-027703), the CDTI CENIT-CDTEAM grant funded by the Spanish Ministry of Science and Innovation (MICINN-CDTI), the AGAUR-FI fellowship from Generalitat de Catalunya, and Philips Healthcare (Best, The Netherlands)

Automated Segmentation of Cerebral Vasculature with Aneurysms in 3DRA and TOF-MRA using Geodesic Active Regions: an Evaluation Study

Purpose: To evaluate the suitability of an improved version of an automatic segmentation method based on geodesic active regions (GAR) for segmenting cerebral vasculature with aneurysms from 3D X-ray reconstruc-/ntion angiography (3DRA) and time of °ight magnetic resonance angiography (TOF-MRA) images available in the clinical routine./nMethods: Three aspects of the GAR method have been improved: execution time, robustness to variability in imaging protocols and robustness to variability in image spatial resolutions. The improved GAR was retrospectively evaluated on images from patients containing intracranial aneurysms in the area of the Circle of Willis and imaged with two modalities: 3DRA and TOF-MRA. Images were obtained from two clinical centers, each using di®erent imaging equipment. Evaluation included qualitative and quantitative analyses of/nthe segmentation results on 20 images from 10 patients. The gold standard was built from 660 cross-sections (33 per image) of vessels and aneurysms, manually measured by interventional neuroradiologists. GAR has also been compared to an interactive segmentation method: iso-intensity surface extraction (ISE). In addition, since patients had been imaged with the two modalities, we performed an inter-modality agreement analysis with respect to both the manual measurements and each of the two segmentation methods. Results: Both GAR and ISE di®ered from the gold standard within acceptable limits compared to the imaging resolution. GAR (ISE, respectively) had an average accuracy of 0.20 (0.24) mm for 3DRA and 0.27 (0.30) mm for TOF-MRA, and had a repeatability of 0.05 (0.20) mm. Compared to ISE, GAR had a lower qualitative error in the vessel region and a lower quantitative error in the aneurysm region. The repeatability/nof GAR was superior to manual measurements and ISE. The inter-modality agreement was similar between GAR and the manual measurements. Conclusions: The improved GAR method outperformed ISE qualitatively as well as quantitatively and is suitable for segmenting 3DRA and TOF-MRA images from clinical routine.The authors would like to acknowledge J. Schneiders for providing part of the TOF-MRA imaging data. The authors would like to thank also A. G. Radaelli, M. Nieber, and X. Planes for the help in implementing some of the methods. This work was partially supported by the @neurIST Integrated Project (co-financed by the European Commission through Contract No. IST-027703), the CDTI CENIT-CDTEAM grant funded by the Spanish Ministry of Science and Innovation (MICINN-CDTI), the AGAUR-FI fellowship from Generalitat de Catalunya, and Philips Healthcare (Best, The Netherlands)