1
|
Kim JH, Park JE, Lee JM. Post-processing calcium subtraction method to minimize stenosis-overestimation by blooming artifact. Technol Health Care 2022; 30:3-10. [PMID: 35124579 PMCID: PMC9028751 DOI: 10.3233/thc-228001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: CT images are often affected by blooming artifacts during the diagnosis that facilitate an overestimation of the expression of calcification stenosis, thereby impeding the accurate diagnosis of this condition. OBJECTIVE: Arterial calcification can act as a blooming artifact in computed tomography (CT) images, leading to overestimations of the blood vessel and the size of calcified plaque. This study proposes an improved CT post-processing method that accurately measures calcium and lumen size in blood vessels. METHODS: Six hundred and thirty calcium datasets were obtained from 63 patients diagnosed with a vascular disease. Patients were grouped into three sets corresponding to each image acquisition method used: G1, for the invasive coronary angiography (ICA); G2, for multiplanar reconstruction (MPR) imaging and post-processing; and G3, for the novel method of mixed Gaussian filter and K-mean clustering (GK). Results of GK were generated by adding Gaussian and k-mean clustering algorithms to the MPR post-processing procedure. The analysis of variance (ANOVA), linear regression, and intraclass correlation coefficient (ICC) were used to compare the accuracy and sensitivity of the different methods. All measurements were performed multiple times to mitigate human error. RESULTS: The ANOVA test revealed no significant differences between the G1 and G3 groups. Hence, linear regression was used to analyze the correlation between the G1 and G3 groups (p< 0.05, R2 = 0.885), and a higher correlation than G1 and G2 was reported (p> 0.05, R2 = 0.432). ICC was performed for reproducibility, wherein high correlation was identified among all groups. CONCLUSIONS: Results of the study indicate that the GK method yields images that are very similar to ICA image measurements. This suggests that the GK can be used as a more effective post-processing method over the inaccurate MPR while remaining non-intrusive when determining the arterial stenosis degree, unlike the ICA.
Collapse
Affiliation(s)
- Jung-Hun Kim
- Bio-Medical Research institute, Kyungpook National University Hospital, Korea
- Bio-Medical Research institute, Kyungpook National University Hospital, Korea
| | - Ji-Eun Park
- Nonlinear Dynamics Laboratory, Kyungpook National University, Sangyeok-dong, Buk-gu, Daegu, Korea
- Department of Biomedical Engineering, Kyungpook National University, Sangyeok-dong, Buk-gu, Daegu, Korea
- Bio-Medical Research institute, Kyungpook National University Hospital, Korea
| | - Jong-Min Lee
- Department of Radiology, School of Medicine, Kyungpook National University, Sangyeok-dong, Buk-gu, Daegu, Korea
| |
Collapse
|
2
|
Oh LCW, Lau KKP, Devapalasundaram A, Buchan K, Kuganesan A, Huynh M. Efficacy of fine focal spot technique in CT angiography of neck. Br J Radiol 2019; 92:20190083. [PMID: 31112401 DOI: 10.1259/bjr.20190083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVES Focal spot size partially defines spatial resolution of a CT system. Many CT tubes have two focal spot sizes, with the finer one allowing more detailed imaging at the cost of photon intensity and increased heat production. Improved X-ray technology and advancement of various generations of iterative reconstruction allow the use of fine focal spot technique in CT angiography. CT neck angiography (CTNA) has been commonly performed as part of stroke imaging or in the trauma setting. This prospective study aimed to assess the efficacy of fine focal spot scanning in vessel clarity improvement, vessel calcification and arterial pulsation artefact reduction on CTNA. METHODS AND MATERIALS Consecutive adult patients of all ages and genders who presented for CTNA were included. All CTNA were scanned with standard focal spot size (SFSS) of 1 × 1 mm in first 4 months while the CTNA in the following 4 months with fine focal spot size (FFSS) of 0.5 × 1 mm. Vessel clarity, calcification and arterial pulsation artefact of arch of aorta, brachiocephalic, subclavian, common carotid, carotid bifurcation, internal carotid, external carotid and vertebral arteries were assessed randomly using a 5-point scale by two blinded radiologists. Results were compared. RESULTS There were 43 patients (mean age 60) with 97 calcified arterial segments in SFSS and 48 patients (mean age 62) with 113 calcified arterial segments in FFSS. 30 % of patients had > 50% carotid artery stenosis. No occlusion or dissection was found in the remaining arteries. Mann-Whitney test showed FFSS performed significantly better for vessel clarity (U: 48238.50, p < .001,r: 0.556) and calcification artefact reduction (U: 2040.50, p < .001,r: 0.564). There was no significant reduction for arterial pulsation artefact. CONCLUSION Fine focal spot technique improves vessel clarity and reduces calcification blooming artefact in CTNA. These benefits may potentially improve the assessment of arterial luminal stenosis and vessel wall pathology, including plaque morphology. ADVANCES IN KNOWLEDGE Beam hardening artefact from calcification particularly in the vessel wall can often reduce the clarity of vessel lumen thus affect accurate assessment of luminal stenosis. Fine focal spot technique has the advantages of reducing beam-hardening artefact of vessel wall calcifications and improving vessel wall clarity, thus it may potentially improve the assessment of arterial luminal stenosis and vessel wall pathology, including plaque morphology. It may become an important CT imaging technique in near future.
Collapse
Affiliation(s)
| | - Kenneth Kwok-Pan Lau
- 2 Department of Diagnostic Imaging, Monash Health, Clayton, Victoria, Australia.,3 Department of Medicine, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | | | - Kevin Buchan
- 5 Clinical Science, Philips Healthcare, Mont Albert, Victoria, Australia
| | - Ahilan Kuganesan
- 6 Department of Diagnostic Imaging, Monash Health, Clayton, Victoria, Australia
| | - Minh Huynh
- 7 Department of Statistics Data Science and Epidemiology, Swinburne University of Technology, Hawthorn, Victoria, Australia
| |
Collapse
|
3
|
Oh LCW, Lau KK, Devapalasundaram A, Buchan K, Ardley N, Huynh M. Efficacy of 'fine' focal spot imaging in CT abdominal angiography. Eur Radiol 2014; 24:3010-6. [PMID: 25097134 DOI: 10.1007/s00330-014-3368-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/26/2014] [Accepted: 07/21/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To assess the efficacy of fine focal spot imaging in calcification beam-hardening artefact reduction and vessel clarity on CT abdominal angiography (CTAA). METHODS Adult patients of any age and gender who presented for CTAA were included. Thirty-nine patients were examined with a standard focal spot size (SFSS) of 1 × 1 mm in the first 3 months while 31 consecutive patients were examined with a fine focal spot size (FFSS) of 1 × 0.5 mm in the following 3 months. Vessel clarity and calcification beam-hardening artefacts of the abdominal aorta, celiac axis, superior mesenteric artery, inferior mesenteric artery, renal arteries, and iliac arteries were assessed using a 5-point grading scale by two blinded radiologists randomly. RESULTS Cohen's Kappa test indicated that on average, there was substantial agreement among reviewers for vessel wall clarity and calcification artefact grading. Mann-Whitney test showed that there was a significant difference between the two groups, with FFSS performing significantly better for vessel clarity (U, 6481.50; p < 0.001; r, 0.73) and calcification artefact reduction (U, 1916; p < 0.001; r, 0.77). CONCLUSION Fine focus CT angiography produces images with better vessel wall clarity and less vessel calcification beam-hardening artefact. KEY POINTS Focal spot size affects the spatial resolution of a CT system. Fine focus CTAA produces images with improved vessel wall clarity. Fine focus CTAA is associated with fewer calcification beam-hardening artefacts. Fine focus CTAA may improve accuracy in assessment of luminal stenosis.
Collapse
Affiliation(s)
- Lawrence Chia Wei Oh
- Department of Diagnostic Imaging, Monash Health, 246 Clayton Road, Clayton, 3168, Victoria, Australia,
| | | | | | | | | | | |
Collapse
|
4
|
van den Boom R, Manniesing R, Oei MTH, van der Woude WJ, Smit EJ, Laue HOA, van Ginneken B, Prokop M. A 4D digital phantom for patient-specific simulation of brain CT perfusion protocols. Med Phys 2014; 41:071907. [DOI: 10.1118/1.4881520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
|
5
|
Huang A, Lee CW, Yang CY, Liu MY, Liu HM. Using Standard Nonenhanced Axial Scans for Cerebral CT Angiography Bone Elimination. Invest Radiol 2010; 45:225-32. [DOI: 10.1097/rli.0b013e3181d4a010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
6
|
Cranial computed tomography angiography with automated bone subtraction: a feasibility study. Invest Radiol 2009; 44:38-43. [PMID: 18836384 DOI: 10.1097/rli.0b013e31818c3d6b] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Computed tomography angiography (CTA) is becoming an increasingly accepted noninvasive alternative to catheter angiography. To display continuous vessel contours without superimposed bone in a similar manner, postprocessing of the CTA data is necessary. Threshold-based techniques often fail in regions of close vessel-bone contact, which frequently requires user interaction to optimize the results. This may be laborious and time consuming. The aim of this study was to assess the feasibility of a fully automated algorithm for bone subtraction in cranial CT angiography. MATERIALS AND METHODS Forty-nine patients underwent cranial CT angiography on 64 slice CT systems. Two scans were performed, one before (mask) and one after (CTA) contrast agent administration. Images were processed with commercially available subtraction software. Two examiners rated the success of overall bone removal and image quality of different vessel segments (n = 34) with a 4-point scale (1 = poor; 4 = excellent); original CTA data served as the reference. RESULTS Subtraction was performed successfully in all cases, overall subtraction quality was high (82% of cases were rated good or excellent). Only 50 of 1666 arterial segments (3%) were rated nondiagnostic. No relevant artificial stenoses of the internal carotid artery (ICA) or vertebral artery along their way through the skull base were detected when comparing CTA source images to bone subtraction computed tomography angiography (BSCTA) images. CONCLUSIONS Automatic subtraction provides diagnostic image quality for 3D visualization of intracranial vessels, free from over projecting bone in a fully automatic way. Aneurysms can be evaluated from all angles, and ICA stenoses at the skull base were easily visualized.
Collapse
|
7
|
Yim PJ, Nosher JL, Burgos A, Haddadin I. Subtraction computed tomographic angiography of calcified arteries: preliminary phantom and clinical studies. Acad Radiol 2009; 16:257-65. [PMID: 19201354 DOI: 10.1016/j.acra.2008.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 06/18/2008] [Accepted: 07/10/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE AND OBJECTIVES The technique of subtraction computed tomographic angiography (sCTA) has been proposed for the evaluation of atherosclerotic disease to address limitations in CTA in highly calcified arteries. However, sCTA has not gained acceptance in clinical practice, in part, due to image artifacts caused by patient motion that occur between the acquisition of the two component images. The purpose of this study was to evaluate the effectiveness of computational image co-registration to obtain sCTA. MATERIALS AND METHODS The study was conducted using a semi-automated implementation of the mutual information (MI) registration algorithm. The results of sCTA were evaluated quantitatively in a phantom representing a calcified artery. Technical success of sCTA was evaluated in 14 calcified arterial segments in two patients. An observer study was carried out to determine interobserver agreement in the interpretation of sCTA. Qualitative observations were made between sCTA and CTA. RESULTS Computation time for performing the co-registration for each 2-cm calcification is less than 1 second. The necessary user interaction required minimal expertise. Measurements of the degree of stenosis in the calcified artery phantom agreed to within 8 +/- 4% of gold-standard measurements. Technical success was demonstrated in all calcifications. Strong interobserver agreement was obtained for the detection of hemodynamically significant stenoses (kappa = 0.86). Several apparent pitfalls in the interpretation of CTA in calcified arteries were noted that could potentially be obviated by sCTA. CONCLUSIONS The study supports the use of a straight-forward implementation of the MI algorithm and provides preliminary evidence validating the use of sCTA in the setting of atherosclerotic disease of the lower extremities.
Collapse
|
8
|
Cervical CT Angiography Comparing Routine Noncontrast and a Late Venous Scan as Masks for Automated Bone Subtraction. Invest Radiol 2008; 43:27-32. [DOI: 10.1097/rli.0b013e31815597ac] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
9
|
Kock MCJM, Dijkshoorn ML, Pattynama PMT, Myriam Hunink MG. Multi-detector row computed tomography angiography of peripheral arterial disease. Eur Radiol 2007; 17:3208-22. [PMID: 17882427 PMCID: PMC2077918 DOI: 10.1007/s00330-007-0729-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2006] [Revised: 07/04/2007] [Accepted: 07/10/2007] [Indexed: 11/28/2022]
Abstract
With the introduction of multi-detector row computed tomography (MDCT), scan speed and image quality has improved considerably. Since the longitudinal coverage is no longer a limitation, multi-detector row computed tomography angiography (MDCTA) is increasingly used to depict the peripheral arterial runoff. Hence, it is important to know the advantages and limitations of this new non-invasive alternative for the reference test, digital subtraction angiography. Optimization of the acquisition parameters and the contrast delivery is important to achieve a reliable enhancement of the entire arterial runoff in patients with peripheral arterial disease (PAD) using fast CT scanners. The purpose of this review is to discuss the different scanning and injection protocols using 4-, 16-, and 64-detector row CT scanners, to propose effective methods to evaluate and to present large data sets, to discuss its clinical value and major limitations, and to review the literature on the validity, reliability, and cost-effectiveness of multi-detector row CT in the evaluation of PAD.
Collapse
Affiliation(s)
- Marc C J M Kock
- Department of Radiology, Room HS 210K, Erasmus MC, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands.
| | | | | | | |
Collapse
|
10
|
Scherl H, Hornegger J, Prümmer M, Lell M. Semi-automatic level-set based segmentation and stenosis quantification of the internal carotid artery in 3D CTA data sets. Med Image Anal 2007; 11:21-34. [PMID: 17126064 DOI: 10.1016/j.media.2006.09.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Revised: 09/25/2006] [Accepted: 09/28/2006] [Indexed: 10/23/2022]
Abstract
We present a new level-set based method to segment and quantify stenosed internal carotid arteries (ICAs) in 3D contrast-enhanced computed tomography angiography (CTA). Within these data sets it is a difficult task to evaluate the degree of stenoses deterministically even for the experienced physician because the actual vessel lumen is hardly distinguishable from calcified plaque and there is no sharp border between lumen and arterial wall. According to our knowledge no commercially available software package allows the detection of the boundary between lumen and plaque components. Therefore in the clinical environment physicians have to perform the evaluation manually. This approach suffers from both intra- and inter-observer variability. The limitation of the manual approach requires the development of a semi-automatic method that is able to achieve deterministic segmentation results of the internal carotid artery via level-set techniques. With the new method different kinds of plaques were almost completely excluded from the segmented regions. For an objective evaluation we also studied the method's performance with four different phantom data sets for which the ground truth of the degree of stenosis was known a priori. Finally, we applied the method to 10 ICAs and compared the obtained segmentations with manual measurements of three physicians.
Collapse
Affiliation(s)
- Holger Scherl
- Institute of Pattern Recognition, Department of Computer Sciences, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstrasse 3, D-91058 Erlangen, Germany.
| | | | | | | |
Collapse
|
11
|
Lell MM, Anders K, Uder M, Klotz E, Ditt H, Vega-Higuera F, Boskamp T, Bautz WA, Tomandl BF. New Techniques in CT Angiography. Radiographics 2006; 26 Suppl 1:S45-62. [PMID: 17050518 DOI: 10.1148/rg.26si065508] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Computed tomographic (CT) angiography has been improved significantly with the introduction of four- to 64-section spiral CT scanners, which offer rapid acquisition of isotropic data sets. A variety of techniques have been proposed for postprocessing of the resulting images. The most widely used techniques are multiplanar reformation (MPR), thin-slab maximum intensity projection, and volume rendering. Sophisticated segmentation algorithms, vessel analysis tools based on a centerline approach, and automatic lumen boundary definition are emerging techniques; bone removal with thresholding or subtraction algorithms has been introduced. These techniques increasingly provide a quality of vessel analysis comparable to that achieved with intraarterial three-dimensional rotational angiography. Neurovascular applications for these various image postprocessing methods include steno-occlusive disease, dural sinus thrombosis, vascular malformations, and cerebral aneurysms. However, one should keep in mind the potential pitfalls of these techniques and always double-check the final results with source or MPR imaging.
Collapse
Affiliation(s)
- Michael M Lell
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Wolters BJBM, Rutten MCM, Schurink GWH, Kose U, de Hart J, van de Vosse FN. A patient-specific computational model of fluid–structure interaction in abdominal aortic aneurysms. Med Eng Phys 2005; 27:871-83. [PMID: 16157501 DOI: 10.1016/j.medengphy.2005.06.008] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Revised: 05/31/2005] [Accepted: 06/22/2005] [Indexed: 10/25/2022]
Abstract
It is generally believed that knowledge of the wall stress distribution could help to find better rupture risk predictors of abdominal aortic aneurysms (AAAs). Although AAA wall stress results from combined action between blood, wall and intraluminal thrombus, previously published models for patient-specific assessment of the wall stress predominantly did not include fluid-dynamic effects. In order to facilitate the incorporation of fluid-structure interaction in the assessment of AAA wall stress, in this paper, a method for generating patient-specific hexahedral finite element meshes of the AAA lumen and wall is presented. The applicability of the meshes is illustrated by simulations of the wall stress, blood velocity distribution and wall shear stress in a characteristic AAA. The presented method yields a flexible, semi-automated approach for generating patient-specific hexahedral meshes of the AAA lumen and wall with predefined element distributions. The combined fluid/solid mesh allows for simulations of AAA blood dynamics and AAA wall mechanics and the interaction between the two. The mechanical quantities computed in these simulations need to be validated in a clinical setting, after which they could be included in clinical trials in search of risk factors for AAA rupture.
Collapse
MESH Headings
- Aortic Aneurysm, Abdominal/pathology
- Biomechanical Phenomena
- Biophysical Phenomena
- Biophysics
- Blood Vessels/pathology
- Clinical Trials as Topic
- Computer Simulation
- Diastole
- Endothelium, Vascular/pathology
- Finite Element Analysis
- Hemorheology
- Humans
- Image Processing, Computer-Assisted
- Imaging, Three-Dimensional
- Models, Anatomic
- Models, Biological
- Models, Cardiovascular
- Models, Statistical
- Models, Theoretical
- Risk Factors
- Software
- Stress, Mechanical
- Systole
Collapse
Affiliation(s)
- B J B M Wolters
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | | | | | | | | | | |
Collapse
|
13
|
Gratama van Andel HAF, Meijering E, van der Lugt A, Vrooman HA, de Monyé C, Stokking R. Evaluation of an improved technique for automated center lumen line definition in cardiovascular image data. Eur Radiol 2005; 16:391-8. [PMID: 16170556 DOI: 10.1007/s00330-005-2854-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 06/15/2005] [Accepted: 06/28/2005] [Indexed: 10/25/2022]
Abstract
The aim of the study was to evaluate a new method for automated definition of a center lumen line in vessels in cardiovascular image data. This method, called VAMPIRE, is based on improved detection of vessel-like structures. A multiobserver evaluation study was conducted involving 40 tracings in clinical CTA data of carotid arteries to compare VAMPIRE with an established technique. This comparison showed that VAMPIRE yields considerably more successful tracings and improved handling of stenosis, calcifications, multiple vessels, and nearby bone structures. We conclude that VAMPIRE is highly suitable for automated definition of center lumen lines in vessels in cardiovascular image data.
Collapse
Affiliation(s)
- Hugo A F Gratama van Andel
- Department of Medical Informatics, Erasmus MC-University Medical Center Rotterdam, Dr. Molewaterplein 50, Room Ee 2167, 3015 GE, Rotterdam, The Netherlands
| | | | | | | | | | | |
Collapse
|
14
|
Hyde DE, Fox AJ, Gulka I, Kalapos P, Lee DH, Pelz DM, Holdsworth DW. Internal Carotid Artery Stenosis Measurement. Stroke 2004; 35:2776-81. [PMID: 15514196 DOI: 10.1161/01.str.0000147037.12223.d5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose—
Clinical trials have shown that carotid endarterectomy reduces stroke risk in symptomatic individuals with severe internal carotid artery (ICA) stenosis. As a result of these trials, digital subtraction angiography (DSA) became a standard of reference for ICA stenosis diagnosis. Newer 3D techniques provide a larger number of views than DSA, which may influence the estimated degree of stenosis. We evaluate this possibility by directly comparing stenosis grades from 3D computed rotational angiography (CRA) and DSA.
Methods—
As a prospective diagnostic study, we performed CRA and DSA on 26 consecutive symptomatic patients. Only 1 angiographic procedure was performed on normal asymptomatic arteries, yielding 42 arteries for comparison. Four neuroradiologists graded the CRA maximum intensity projections (MIPs) and DSA images, according to the North American Symptomatic Carotid Endarterectomy Trial guidelines. CRA studies included a search for the narrowest view by evaluating 60 MIPs generated at 3° intervals and measurement of actual artery diameters. Artery diameters and stenosis grades were analyzed graphically; statistical significance was determined using a paired
t
test.
Results—
The mean difference of 1.2% (CI, −18%, 21%) between CRA and DSA stenosis grades was not statistically significant (
P
=0.55). Agreement of the optimal CRA viewing angle was limited, with an interobserver variability of 24±13°. The interobserver variability of DSA and CRA stenosis grades, 9.1% (CI, 0%, 21%) and 9.4% (CI, 0%, 22%), respectively, was not significantly different (
P
=0.79).
Conclusion—
CRA provides stenosis grades equivalent to DSA, as well as absolute measurements, providing a comparison for newer 3D techniques.
Collapse
Affiliation(s)
- Derek E Hyde
- Robarts Research Institute, Imaging Research Laboratories, London, Ontario, Canada
| | | | | | | | | | | | | |
Collapse
|
15
|
van Straten M, Venema HW, Streekstra GJ, Majoie CBLM, den Heeten GJ, Grimbergen CA. Removal of bone in CT angiography of the cervical arteries by piecewise matched mask bone elimination. Med Phys 2004; 31:2924-33. [PMID: 15543801 DOI: 10.1118/1.1797511] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In maximum intensity projection (MIP) images of CT angiography (CTA) scans, the arteries are often obscured by bone. A bone removal method is presented that uses an additional, nonenhanced scan to create a mask of the bone by thresholding and dilation. After registration of the CTA scan and the additional scan, the bone in the CTA scan is masked. As the cervical area contains bones that can move with respect to each other, these bones are separated first using a watershed algorithm, and then registered individually. A phantom study was performed to evaluate and quantify the tradeoff between the removal of the bone and the preservation of the arteries contiguous to the bone. The influence of algorithm parameters and scan parameters was studied. The method was clinically evaluated with data sets of 35 patients. Best results were obtained with a threshold of 150 HU and a dilation of 8 in-plane voxels and two out-of-plane voxels. The mean width of the soft tissue layer, which is also masked, was approximately 1 mm. The mAs value of the nonenhanced scan could be reduced from 250 mAs to 65 mAs without a loss of quality. In 32 cases the bones were registered correctly and removed completely. In three cases the bone separation was not completely successful, and consequently the bone was not completely removed. The piecewise matched mask bone elimination method proved to be able to obtain MIP images of the cervical arteries free from overprojecting bone in a fully automatic way and with only a slight increase of radiation dose.
Collapse
Affiliation(s)
- Marcel van Straten
- Department of Medical Physics, Academic Medical Center, Amsterdam, The Netherlands.
| | | | | | | | | | | |
Collapse
|
16
|
van Straten M, Venema HW, Hartman J, den Heeten GJ, Grimbergen CA. Reproducibility of multi-slice spiral computed tomography scans:An experimental study. Med Phys 2004; 31:2785-6. [PMID: 15543784 DOI: 10.1118/1.1796131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In multi-slice spiral computed tomography (CT) images interpolation artifacts are present. The relationship between the x-ray tube rotation angle and these artifacts is demonstrated. A head phantom was repeatedly scanned with a four-slice CT scanner at different pitch values. Two scans, made with identical scan parameters, nearly always have different x-ray tube starting angles. Consequently, artifacts appeared differently and residual artifacts appeared when subtractions were made. We conclude that only if the x-ray tube starting angle is equal for both scans or if a very low pitch is used, images are highly reproducible.
Collapse
Affiliation(s)
- Marcel van Straten
- Department of Medical Physics, Academic Medical Center, Amsterdam, The Netherlands.
| | | | | | | | | |
Collapse
|
17
|
Chu Q, Li Z, Zhang SM, Hu DY, Xiao M. Relationship between encephalopathy and portal vein-vena cava shunt: Value of computed tomography during arterial portography. World J Gastroenterol 2004; 10:1939-42. [PMID: 15222041 PMCID: PMC4572235 DOI: 10.3748/wjg.v10.i13.1939] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To assess the value of computed tomography during arterial portography (CTAP) in portal vein-vena cava shunt, and analysis of the episode risk in encephalopathy.
METHODS: Twenty-nine patients with portal-systemic encephalopathy due to portal hypertension were classified by West Haven method into grade I (29 cases), grade II (16 cases), grade III (10 cases), grade IV ( 4 cases). All the patients were scanned by spiral-CT. Plane scans, artery phase and portal vein phase enhancement scans were performed, and the source images were thinly reconstructed to 1.25 mm. We reconstructed the celiac trunk, portal vein, inferior vena cava and their branches and subjected them to three-dimensional vessel analysis by volume rendering (VR) technique and multiplanar volume reconstruction (MPVR) technique. The blood vessel reconstruction technique was used to evaluate the scope and extent of portal vein-vena cava shunt, portal vein emboli and the fistula of hepatic artery-portal vein. The relationship between the episode risk of portal-systemic encephalopathy and the scope and extent of portal vein-vena cava shunt, portal vein emboli and fistula of hepatic artery-portal vein was studied.
RESULTS: The three-dimensional vessel reconstruction technique of spiral-CT could display celiac trunk, portal vein, inferior vena cava and their branches at any planes and angles and the scope and extent of portal vein-vena cava shunt, portal vein emboli and the fistula of hepatic artery-portal vein. In twenty-nine patients with portal-systemic encephalopathy, grade I accounted for 89.7% esophageal varices, 86.2% paragastric varices; grade II accounted for 68.75% cirsomphalos, 56.25% paraesophageal varices, 62.5% retroperitoneal varices and 81.25% dilated azygos vein; grade III accounted for 80% cirsomphalos, 60% paraesophageal varices, 70% retroperitoneal varices, 90% dilated azygos vein, and part of the patients in grades II and III had portal vein emboli and fistula of hepatic artery-portal vein; grade IV accounted for 75% dilated left renal vein, 50% paragallbladder varices, all the patients had fistula of hepatic artery-portal vein.
CONCLUSION: The three-dimensional vessel reconstruction technique of spiral-CT can clearly display celiac trunk, portal vein, inferior vena cava and their branches at any planes and angles and the scope and extent of portal vein-vena cava shunt. The technique is valuable for evaluating the episode risk in portal-systemic encephalopathy.
Collapse
Affiliation(s)
- Qian Chu
- Department of Neurology, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China.
| | | | | | | | | |
Collapse
|