1
|
Guedes Pinto E, Penha D, Ravara S, Monaghan C, Hochhegger B, Marchiori E, Taborda-Barata L, Irion K. Factors influencing the outcome of volumetry tools for pulmonary nodule analysis: a systematic review and attempted meta-analysis. Insights Imaging 2023; 14:152. [PMID: 37741928 PMCID: PMC10517915 DOI: 10.1186/s13244-023-01480-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 07/08/2023] [Indexed: 09/25/2023] Open
Abstract
Health systems worldwide are implementing lung cancer screening programmes to identify early-stage lung cancer and maximise patient survival. Volumetry is recommended for follow-up of pulmonary nodules and outperforms other measurement methods. However, volumetry is known to be influenced by multiple factors. The objectives of this systematic review (PROSPERO CRD42022370233) are to summarise the current knowledge regarding factors that influence volumetry tools used in the analysis of pulmonary nodules, assess for significant clinical impact, identify gaps in current knowledge and suggest future research. Five databases (Medline, Scopus, Journals@Ovid, Embase and Emcare) were searched on the 21st of September, 2022, and 137 original research studies were included, explicitly testing the potential impact of influencing factors on the outcome of volumetry tools. The summary of these studies is tabulated, and a narrative review is provided. A subset of studies (n = 16) reporting clinical significance were selected, and their results were combined, if appropriate, using meta-analysis. Factors with clinical significance include the segmentation algorithm, quality of the segmentation, slice thickness, the level of inspiration for solid nodules, and the reconstruction algorithm and kernel in subsolid nodules. Although there is a large body of evidence in this field, it is unclear how to apply the results from these studies in clinical practice as most studies do not test for clinical relevance. The meta-analysis did not improve our understanding due to the small number and heterogeneity of studies testing for clinical significance. CRITICAL RELEVANCE STATEMENT: Many studies have investigated the influencing factors of pulmonary nodule volumetry, but only 11% of these questioned their clinical relevance in their management. The heterogeneity among these studies presents a challenge in consolidating results and clinical application of the evidence. KEY POINTS: • Factors influencing the volumetry of pulmonary nodules have been extensively investigated. • Just 11% of studies test clinical significance (wrongly diagnosing growth). • Nodule size interacts with most other influencing factors (especially for smaller nodules). • Heterogeneity among studies makes comparison and consolidation of results challenging. • Future research should focus on clinical applicability, screening, and updated technology.
Collapse
Affiliation(s)
- Erique Guedes Pinto
- R. Marquês de Ávila E Bolama, Universidade da Beira Interior Faculdade de Ciências da Saúde, 6201-001, Covilhã, Portugal.
| | - Diana Penha
- R. Marquês de Ávila E Bolama, Universidade da Beira Interior Faculdade de Ciências da Saúde, 6201-001, Covilhã, Portugal
- Liverpool Heart and Chest Hospital NHS Foundation Trust, Thomas Dr, Liverpool, L14 3PE, UK
| | - Sofia Ravara
- R. Marquês de Ávila E Bolama, Universidade da Beira Interior Faculdade de Ciências da Saúde, 6201-001, Covilhã, Portugal
| | - Colin Monaghan
- Liverpool Heart and Chest Hospital NHS Foundation Trust, Thomas Dr, Liverpool, L14 3PE, UK
| | | | - Edson Marchiori
- Faculdade de Medicina, Universidade Federal Do Rio de Janeiro, Bloco K - Av. Carlos Chagas Filho, 373 - 2º Andar, Sala 49 - Cidade Universitária da Universidade Federal Do Rio de Janeiro, Rio de Janeiro - RJ, 21044-020, Brasil
- Faculdade de Medicina, Universidade Federal Fluminense, Av. Marquês Do Paraná, 303 - Centro, Niterói - RJ, 24220-000, Brasil
| | - Luís Taborda-Barata
- R. Marquês de Ávila E Bolama, Universidade da Beira Interior Faculdade de Ciências da Saúde, 6201-001, Covilhã, Portugal
| | - Klaus Irion
- Manchester University NHS Foundation Trust, Manchester Royal Infirmary, Oxford Rd, Manchester, M13 9WL, UK
| |
Collapse
|
2
|
Nageh M, Ibrahim LA, AbuNaeem FM, Salam E. Management of internal inflammatory root resorption using injectable platelet-rich fibrin revascularization technique: a clinical study with cone-beam computed tomography evaluation. Clin Oral Investig 2021; 26:1505-1516. [PMID: 34387731 DOI: 10.1007/s00784-021-04123-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 07/30/2021] [Indexed: 12/13/2022]
Abstract
OBJECTIVES The current study evaluated clinically and radiographically the management of internal inflammatory root resorption (IIRR) in permanent anterior teeth with or without periapical lesions using injectable platelet-rich fibrin (i-PRF) regenerative approach. METHODS Ten systemically healthy patients, with thirteen anterior mature teeth diagnosed with IIRR were selected for the study. At the first visit, the tooth was anesthetized, access cavity opened, root canals were mechanically prepared then medicated with calcium hydroxide and temporarily sealed. After 2-4 weeks, regenerative endodontic procedures were performed by preparing and applying i-PRF inside the canal, then a freshly prepared PRF membrane was placed over it. White mineral trioxide aggregate was placed over the PRF matrix, and the tooth was restored with a glass ionomer cement base and resin composite restoration. The patients were recalled for clinical and radiographic evaluation and follow-up every 3 months for 12 months. Cone-beam computed tomography (CBCT) imaging was performed preoperatively and after 12 months. RESULTS Clinical evaluation results showed resolution of signs and symptoms through the follow-up period in all of the cases. Both CBCT imaging readings of IIRR lesions and periapical lesions revealed a volumetric significant difference (p = 0.00) between the preoperative and the 12-month follow-up period. CONCLUSIONS Usage of i-PRF could arrest and allow for healing of IIRR in permanent mature teeth and allow for periapical healing with successful clinical results. CLINICAL RELEVANCE i-PRF revascularization technique proved to be a successful REP in the treatment of the IIRR, reducing the number of appointments and increasing patient compliance.
Collapse
Affiliation(s)
- Mohamed Nageh
- Department of Endodontics, Faculty of Dentistry, Fayoum University, Batal Al-Salam Street, Al bahary, Fayoum, Egypt.
| | - Lamiaa A Ibrahim
- Department of Endodontics, Faculty of Dentistry, Fayoum University, Batal Al-Salam Street, Al bahary, Fayoum, Egypt
| | - Fatma M AbuNaeem
- Department of Endodontics, Faculty of Dentistry, Cairo University, 11 Sarya el Manyal Street, Manyal, Cairo, Egypt
| | - Engy Salam
- Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Fayoum University, Batal Al-Salam Street, Al bahary, Fayoum, Egypt
| |
Collapse
|
3
|
Individual Optimization of the Insertion of a Preformed Cochlear Implant Electrode Array. Int J Otolaryngol 2015; 2015:724703. [PMID: 26448764 PMCID: PMC4581552 DOI: 10.1155/2015/724703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 08/06/2015] [Indexed: 11/21/2022] Open
Abstract
Purpose. The aim of this study was to show that individual adjustment of the curling behaviour of a preformed cochlear implant (CI) electrode array to the patient-specific shape of the cochlea can improve the insertion process in terms of reduced risk of insertion trauma. Methods. Geometry and curling behaviour of preformed, commercially available electrode arrays were modelled. Additionally, the anatomy of each small, medium-sized, and large human cochlea was modelled to consider anatomical variations. Finally, using a custom-made simulation tool, three different insertion strategies (conventional Advanced Off-Stylet (AOS) insertion technique, an automated implementation of the AOS technique, and a manually optimized insertion process) were simulated and compared with respect to the risk of insertion-related trauma. The risk of trauma was evaluated using a newly developed “trauma risk” rating scale. Results. Using this simulation-based approach, it was shown that an individually optimized insertion procedure is advantageous compared with the AOS insertion technique. Conclusion. This finding leads to the conclusion that, in general, consideration of the specific curling behaviour of a CI electrode array is beneficial in terms of less traumatic insertion. Therefore, these results highlight an entirely novel aspect of clinical application of preformed perimodiolar electrode arrays in general.
Collapse
|
4
|
Barfett J, Velauthapillai N, Kloeters C, Mikulis DJ, Jaskolka JD. An en bloc approach to CT perfusion for the evaluation of limb ischemia. Int J Cardiovasc Imaging 2013; 28:2073-83. [PMID: 22286394 DOI: 10.1007/s10554-011-9978-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Accepted: 11/03/2011] [Indexed: 01/01/2023]
Abstract
We examine volumetric CT perfusion in soft tissues of the entire foot with an en bloc technique to provide a meaningful measure of differentiation between mild and major vascular impairment. With Institutional Review Board approval, 22 healthy male subjects between the ages of 21 and 50 (mean 37) were enrolled. Volumetric computed tomography using an en bloc technique was conducted on 14 subjects for validation while unilateral vascular obstruction was simulated in the calves of the remaining 8 subjects. Perfusion estimates were made using in-house software and differences in perfusion estimates between feet were evaluated with Student's t-test at 95% confidence. Subjects with simulated major vascular obstruction (calf blood pressure cuff inflated to 200 mmHg) showed significantly higher ratios of perfusion estimates between the unobstructed and obstructed foot compared to subjects with simulated mild vascular obstruction (cuff inflated to 120 mmHg), mean 4.6, SD 2.6 vs. mean 1.3, SD 0.2; P = 0.05. CT perfusion using an en bloc technique shows promise for the future evaluation of patients with critical limb ischemia and particularly for re-characterization post medical, surgical or endovascular intervention.
Collapse
Affiliation(s)
- Joe Barfett
- Medical Imaging, University Health Network, 399 Bathurst St., McLaughlin Pavilion, 3rd Floor Rm 431, Toronto, ON, M5T 2S8, Canada.
| | | | | | | | | |
Collapse
|
5
|
Ahlowalia MS, Patel S, Anwar HMS, Cama G, Austin RS, Wilson R, Mannocci F. Accuracy of CBCT for volumetric measurement of simulated periapical lesions. Int Endod J 2012; 46:538-46. [DOI: 10.1111/iej.12023] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 10/07/2012] [Indexed: 12/12/2022]
Affiliation(s)
- M. S. Ahlowalia
- Department of Conservative Dentistry; Dental Institute; King's College London; London; UK
| | - S. Patel
- Department of Conservative Dentistry; Dental Institute; King's College London; London; UK
| | - H. M. S. Anwar
- Department of Conservative Dentistry; Dental Institute; King's College London; London; UK
| | - G. Cama
- Department of Conservative Dentistry; Dental Institute; King's College London; London; UK
| | - R. S. Austin
- Department of Conservative Dentistry; Dental Institute; King's College London; London; UK
| | - R. Wilson
- Department of Conservative Dentistry; Dental Institute; King's College London; London; UK
| | - F. Mannocci
- Department of Conservative Dentistry; Dental Institute; King's College London; London; UK
| |
Collapse
|
6
|
Mulder L, van Rietbergen B, Noordhoek NJ, Ito K. Determination of vertebral and femoral trabecular morphology and stiffness using a flat-panel C-arm-based CT approach. Bone 2012; 50:200-8. [PMID: 22057082 DOI: 10.1016/j.bone.2011.10.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/22/2011] [Accepted: 10/19/2011] [Indexed: 01/04/2023]
Abstract
The importance of assessing trabecular architecture together with bone mineral density to determine bone stiffness and fracture risk in osteoporosis has been well established. However, no imaging modalities are available to assess trabecular architecture at clinically relevant sites in the axial skeleton. Recently developed flat-panel CT devices, however, offer resolutions that are potentially good enough to resolve bone architecture at these sites. The goal of the present study was to investigate how accurate trabecular architecture and stiffness can be determined based on images from such a device (XperCT, Philips Healthcare). Ten cadaver human C3 vertebrae, twelve T12 vertebrae and 12 proximal femora were scanned with XperCT while mimicking in-vivo scanning conditions and compared to scans of the same bones with microCT. Standard segmentation and morphology quantification algorithms were applied as well as finite element (FE) simulation based on segmented and gray value images. Results showed that mean trabecular separation (Tb.Sp) and number (Tb.N) can be accurately determined at all sites. The accuracy of other parameters, however, depended on the site. For T12 no other structural parameters could be accurately quantified and no FE-results could be obtained from segmented images. When using gray-level images, however, accurate determination of cancellous bone stiffness was possible. For the C3 vertebrae and proximal femora, mean bone volume fraction (BV/TV), Tb.Sp, Tb.N, and anisotropy (C3 only) could be determined accurately. For Tb.Th, structure model index (SMI, femur only), and anisotropy good correlations were obtained but the values were not determined accurately. FE simulations based on segmented images were accurate for the C3 vertebrae, but severely underestimated bone stiffness for the femur. Here also, this was improved by using the gray value models. In conclusion, XperCT does provide a resolution that is good enough to determine trabecular architecture, but the signal to noise ratio is key to the accuracy of the morphology measurement. When the trabeculae are thick e.g. in the femur or the noise is low, e.g. cervical spine, architecture and stiffness could be determined accurately, but when the trabeculae are thin and the noise is high, e.g. thoracic spine, architecture could not be determined accurately and the connectivity was lost and hence no mechanical properties could be calculated directly.
Collapse
Affiliation(s)
- Lars Mulder
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | | | | | | |
Collapse
|
7
|
Fricke-Zech S, Gruber RM, Dullin C, Zapf A, Kramer FJ, Kubein-Meesenburg D, Hahn W. Measurement of the midpalatal suture width. Angle Orthod 2011; 82:145-50. [PMID: 21812573 DOI: 10.2319/040311-238.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE To conduct a pilot study to investigate the potentiality to determine the midpalatal sutural width radiographically with a flat-panel volume computed tomography (fpVCT) in a porcine model. MATERIALS AND METHODS Bone samples from the midpalatal suture of five young (16 weeks) and five old (200 weeks) sus scrofa domestica were gathered. The midpalatal suture width was measured via fpVCT and compared to respective histological preparations. Results with P < .05 were considered significant. RESULTS The data obtained by fpVCT and by histomorphometric analysis reveal a highly significant age dependency of the measured suture width (both P < .0001), with lower suture width values in older subjects compared to the younger group. The averaged suture widths measured in the fpVCT images shows a distinctively higher mean compared to the histomorphometric data with high statistical significance (P < .0001). The evaluated difference between both methods was almost constant. CONCLUSION fpVCT is a powerful tool for determining midpalatal sutural width.
Collapse
Affiliation(s)
- Susanne Fricke-Zech
- Department of Orthodontics, Georg-August-University of Goettingen, Goettingen, Germany.
| | | | | | | | | | | | | |
Collapse
|
8
|
Ionescu M, Metcalfe RW, Cody D, Alvarado MVY, Hipp J, Benndorf G. Spatial resolution limits of multislice computed tomography (MS-CT), C-arm-CT, and flat panel-CT (FP-CT) compared to MicroCT for visualization of a small metallic stent. Acad Radiol 2011; 18:866-75. [PMID: 21669352 DOI: 10.1016/j.acra.2011.02.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Revised: 02/04/2011] [Accepted: 02/04/2011] [Indexed: 11/26/2022]
Abstract
RATIONALE AND OBJECTIVES Small metallic stents are increasingly used in the treatment of cerebral aneurysms and for revascularization in ischemic strokes. Realistic three-dimensional datasets of a stent were obtained by using three x-ray-based imaging methods in current clinical use. Multislice-CT (MS-CT), C-arm flat detector-CT (C-arm CT, ACT), and flat panel-CT (FP-CT) were compared with high-resolution laboratory MicroCT scans that served as a reference standard. The purpose was to assess and compare the quality and accuracy of current clinical three-dimensional reconstructions of a vascular stents. MATERIAL & METHODS A 3 × 20 mm Cypher stent was deployed in a straight polytetrafluoroethylene tube and filled with nondiluted iodine contrast and BaSO(4). MS-CT images of the static tube phantom and stent were acquired using GE LightSpeed VCT Series, C-arm CT images were obtained using Artis (DynaCT, Siemens), FP-CT were obtained using a preclinical research CT (GE), and MicroCT images were obtained using eXplore Locus SP (GE). DICOM datasets were analyzed using Amira and Matlab. RESULTS Because of blooming effects, the maximum intensity projections (MIPs) and volume renderings generated from MS-CT showed significantly increased strut dimensions with no distinction between the regular struts and connector struts while the lumen diameter is artificially reduced. The shape of the reconstructed stent surface differed remarkably from the real stent. C-arm CT and FP-CT volume renderings more accurately represented the struts. Consistently capturing the structure of the connectors and the strut shape definition was highly threshold dependent. The stent lumen was about 30% underestimated by MS-CT when compared to MicroCT. CONCLUSION The spatial resolution of current clinical CT for imaging of small metallic stents is insufficient to visualize fine geometrical details. Further improvement in the spatial resolution of clinical imaging technologies combined with better software and hardware for image postprocessing will be necessary for detailed structural analysis, evaluation of the stent lumen in vivo, and to permit accurate assessment of stent patency and early detection potential in-stent stenosis.
Collapse
|
9
|
|
10
|
Barfett JJ, Fierstra J, Willems PWA, Mikulis DJ, Krings T. Intravascular functional maps of common neurovascular lesions derived from volumetric 4D CT data. Invest Radiol 2010; 45:370-7. [PMID: 20479649 DOI: 10.1097/rli.0b013e3181e1939d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE Current computed tomography angiography (CTA) postprocessing tools do not support quantitative assessment of intravascular physiology. Dynamic volumetric CT, acquired at a sufficiently high temporal resolution, is ideal for such analysis. Following preliminary experiments in flow phantoms, we examine the segmentation of blood vessels from 4D CT angiography by curve fit and encoding of functional blood flow information into the resulting functional intravascular maps. MATERIALS AND METHODS Flow phantoms were constructed consisting of a single pipe input and 4 simultaneous outputs of varying flow rates. Two outflow pipe diameters were tested. Bolus transit time (TT), time to peak (TTP), and time of arrival (TOA) were analyzed using contrast bolus profiles generated from 4D volumetric CT examinations on a 320 detector scanner in regions of interest placed 10 cm apart in all outflow pipes. Six subjects with various neurovascular lesions were next examined using a volumetric contrast-enhanced 4D CT angiography protocol. Segmentation was performed by quadratic curve fit after comparative analysis and optimization of the segmentation technique using quadratic curves, the gamma variate function, and a simplified formulation of the gamma variate function. After segmentation, quantitative analysis of spatially congruent intravascular voxels including TTP, rise, TT, and slope of the contrast upstroke was employed to encode physiologic information into the segmentations and produce intravascular functional maps. Comparison was made in each case to the patient's routine imaging. RESULTS Increasing volumetric flow rates correspond to reduction of bolus TT in flow phantoms. TT elongation was observed as the contrast bolus moved distally in all pipes, with greater elongation seen at slower flow rates and larger pipe diameters. A greater difference was observed between TTP proximally and distally in pipes compared with TOA, an effect most prominent at slower flow rates and larger pipe lumens, and thus TTP was chosen for functional encoding into segmentations of the clinical series. In vivo, the quadratic function demonstrated the lowest coefficient of variation when fit to intravascular time density series and outperformed 2 formulations of the gamma variate function. After segmentation with quadratic curves, Gaussian distributions were chosen over gamma variate functions to characterize contrast bolus profiles while neglecting recirculation and to calculate functional parameters for spatial encoding. Intravascular functional maps free of bone artifacts were created in every case that demonstrated all appropriate vessels and showed agreement with conventional imaging modalities in terms of vessel delineation and the diagnosis of vascular pathology. The most useful and interesting functional maps are discussed in each case. CONCLUSIONS The above approach to quantitative CT angiography provides a method of evaluating dynamic CTA data by means of intravascular functional maps. The techniques are broadly applicable in the clinical assessment of a variety of vascular diseases.
Collapse
Affiliation(s)
- Joe J Barfett
- Division of Neuroradiology, Department of Medical Imaging, University Health Network, Toronto Western Hospital, Toronto, ON, Canada
| | | | | | | | | |
Collapse
|
11
|
MARTEN K, DULLIN C, MACHANN W, SCHMID JS, DAS M, HERMANN KP, ENGELKE C. Comparison of flat-panel-detector-based CT and multidetector-row CT in automated volumetry of pulmonary nodules using an anthropomorphic chest phantom. Br J Radiol 2009; 82:716-23. [DOI: 10.1259/bjr/40733553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
|
12
|
|
13
|
Granton PV, Pollmann SI, Ford NL, Drangova M, Holdsworth DW. Implementation of dual- and triple-energy cone-beam micro-CT for postreconstruction material decomposition. Med Phys 2009; 35:5030-42. [PMID: 19070237 DOI: 10.1118/1.2987668] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Micro-CT has become a powerful tool for small animal research, having the ability to obtain high-resolution in vivo and ex vivo images for analyzing bone mineral content, organ vasculature, and bone microarchitecture extraction. The use of exogenous contrast agents further extends the use of micro-CT techniques, but despite advancements in contrast agents, single-energy micro-CT is still limited in cases where two different materials share similar grey-scale intensity values. This study specifically addresses the development of multiple-energy cone-beam micro-CT, for applications where bone must be separated from blood vessels filled with a Pb-based contrast material (Microfil) in ex vivo studies of rodents and tissue specimens. The authors report the implementation of dual- and triple-energy CT algorithms for material-specific imaging using postreconstruction decomposition of micro-CT data; the algorithms were implemented on a volumetric cone-beam micro-CT scanner (GE Locus Ultra). For the dual-energy approach, extrinsic filtration was applied to the x-ray beam to produce spectra with different proportions of x rays above the K edge of Pb. The optimum x-ray tube energies (140 kVp filtered with 1.45 mm Cu and 96 kVp filtered with 0.3 mm Pb) that maximize the contrast between bone and Microfil were determined through numerical simulation. For the triple-energy decomposition, an additional low-energy spectrum (70 kVp, no added filtration) was used. The accuracy of decomposition was evaluated through simulations and experimental verification of a phantom containing a cortical bone simulating material (SB3), Microfil, and acrylic. Using simulations and phantom experiments, an accuracy greater than 95% was achieved in decompositions of bone and Microfil (for noise levels lower than 11 HU), while soft tissue was separated with accuracy better than 99%. The triple-energy technique demonstrated a slightly higher, but not significantly different, decomposition accuracy than the dual-energy technique for the same achieved noise level in the micro-CT images acquired at the multiple energies. The dual-energy technique was applied to the decomposition of an ex vivo rat specimen perfused with Microfil; successful decomposition of the bone and Microfil was achieved, enabling the visualization and characterization of the vasculature both in areas where the vessels traverse soft tissue and when they are surrounded by bone. In comparison, in single energy micro-CT, vessels surrounded by bone could not be distinguished from the cortical bone, based on grey-scale intensity alone. This work represents the first postreconstruction application of material-specific decomposition that directly takes advantage of the K edge characteristics of a contrast material injected into an animal specimen; the application of the technique resulted in automatic, accurate segmentation of 3D micro-CT images into bone, vessel, and tissue components. The algorithm uses only reconstructed images, rather than projection data, and is calibrated by an operator with signal values in regions identified as being comprised entirely of either cortical bone, contrast-enhanced vessel, or soft tissue; these required calibration values are observed directly within reconstructed CT images acquired at the multiple energies. These features facilitate future implementation on existing research micro-CT systems.
Collapse
Affiliation(s)
- P V Granton
- Department of Physics and Astronomy, University of Western Ontario, London Ontario N6A 3K7, Canada
| | | | | | | | | |
Collapse
|
14
|
Kau T, Rabitsch E, Celedin S, Jeschofnig B, Illiasch H, Eicher W, Uhl E, Honl M, Hausegger KA. Feasibility and potential value of flat-panel detector–based computed tomography in myelography after spinal surgery. J Neurosurg Spine 2009; 10:66-72. [DOI: 10.3171/2008.10.spi08627] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
The purpose of this study was to assess the value of myelography using flat-panel detector–based computed tomography (fpCT) in 5 patients in whom the image quality of multislice CT (MSCT) or MR imaging was limited by metal artifacts.
Methods
The application of fpCT to myelographic imaging of the lumbar spine and cervicothoracic junction after surgery was feasible. Multiplanar, preferably sagittal, and 3D reconstructions adequately depicted disc space implants and provided high resolution images of osseous structures.
Results
The images obtained with fpCT allowed evaluation of anatomical details such as single nerve roots and proved especially valuable in a patient with impaired MR imaging results caused by metal artifacts from an intraoperative abrasion. In a case of recurrent disc herniation, imaging results of myelographic fpCT and MSCT scanning were in good agreement.
Conclusions
The novel imaging technique the authors describe yielded adequate results in patients with a history of spinal surgery, may be superior to MSCT scanning in depicting osseous structures and metallic implants, and has the potential to provide multilevel spinal images. Myelographic fpCT scanning may be the preferred modality in patients with expected or known metal artifacts on myelographic MSCT scans and/or MR images.
Collapse
Affiliation(s)
- Thomas Kau
- 1Institute of Diagnostic and Interventional Radiology; and
| | - Egon Rabitsch
- 1Institute of Diagnostic and Interventional Radiology; and
| | - Stefan Celedin
- 1Institute of Diagnostic and Interventional Radiology; and
| | | | | | | | | | - Matthias Honl
- 3Orthopedic Surgery, General Hospital of Klagenfurt, Austria
| | | |
Collapse
|
15
|
Four Dimensional Intravenous Cone-Beam Computed Tomographic Subtraction Angiography. Invest Radiol 2008; 43:753-61. [DOI: 10.1097/rli.0b013e3181812c4c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|
16
|
Badea CT, Drangova M, Holdsworth DW, Johnson GA. In vivo small-animal imaging using micro-CT and digital subtraction angiography. Phys Med Biol 2008; 53:R319-50. [PMID: 18758005 DOI: 10.1088/0031-9155/53/19/r01] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Small-animal imaging has a critical role in phenotyping, drug discovery and in providing a basic understanding of mechanisms of disease. Translating imaging methods from humans to small animals is not an easy task. The purpose of this work is to review in vivo x-ray based small-animal imaging, with a focus on in vivo micro-computed tomography (micro-CT) and digital subtraction angiography (DSA). We present the principles, technologies, image quality parameters and types of applications. We show that both methods can be used not only to provide morphological, but also functional information, such as cardiac function estimation or perfusion. Compared to other modalities, x-ray based imaging is usually regarded as being able to provide higher throughput at lower cost and adequate resolution. The limitations are usually associated with the relatively poor contrast mechanisms and potential radiation damage due to ionizing radiation, although the use of contrast agents and careful design of studies can address these limitations. We hope that the information will effectively address how x-ray based imaging can be exploited for successful in vivo preclinical imaging.
Collapse
Affiliation(s)
- C T Badea
- Center for In Vivo Microscopy, Department of Radiology, Duke University, Durham, NC 27710, USA
| | | | | | | |
Collapse
|
17
|
Schnapauff D, Zimmermann E, Dewey M. Technical and Clinical Aspects of Coronary Computed Tomography Angiography. Semin Ultrasound CT MR 2008; 29:167-75. [DOI: 10.1053/j.sult.2008.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
18
|
Heuser M, Hemmerlein B, Püsken M, Koskinas N, Dullin C, Gross AJ, Zöller GM, Obenauer S. [Determination of renal carcinoma progression in small animals by means of flat-panel volumetric computer tomography]. Urologe A 2007; 46:1710-4. [PMID: 17932642 DOI: 10.1007/s00120-007-1568-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE We investigated the feasibility of using flat panel volumetric computer tomography (fpVCT) for the detection of orthotopically implanted renal carcinomas in nude mice. MATERIALS AND METHODS One million renal cell carcinoma cells [A-498 line (Braunschweig, Germany), in 0.2 ml phosphate-buffered solution (PBS), pH 7.4] were injected into the left kidney of each of the eight nude mice. Each mouse was imaged twice (12 and 16 weeks after implantation) with fpVCT (GE prototype with circular gantry with two 1024 x 1024, 200 microm pixel size, aSi/CsI flat panel detector) after injection of 200 microl contrast medium to check for tumour spread. After 16 weeks the mice were killed and dissected, and the imaging findings in liver, kidneys and lung were compared with the macroscopic findings. RESULTS No local evidence of tumour or of metastatic spread was seen on fpVCT after 12 weeks in any of the mice. After 16 weeks fpVCT revealed tumour growth in 6 of the 16 kidneys. Two mice had each developed a multifocal renal cell carcinoma and one mouse, a bilateral renal tumour manifestation. In one mouse liver metastases were seen. The fpVCT findings correlated well with the observations recorded in the pathological examination. CONCLUSION fpVCT is an innovative and noninvasive imaging procedure that can be used for longitudinal investigation of tumour progression following orthotopic implantation of renal cell carcinoma to small animals. The use of a system of this kind will make a decisive contribution to reducing the number of animals used in experimental test projects.
Collapse
Affiliation(s)
- M Heuser
- Abteilung für Urologie, Asklepios Stadtklinik, Brunnenallee 19, Bad Wildungen, Germany.
| | | | | | | | | | | | | | | |
Collapse
|