| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Original Research |
1 The Russell H. Morgan Department of Radiology and Radiological Science, Johns
Hopkins Medical Institutions, Baltimore, MD; and Department of Radiology,
Johns Hopkins Outpatient Center, JHOC 3235, 601 N Caroline St., Baltimore, MD
21287.
2 Department of Radiology, New York University Medical Center, New York,
NY.
3 Department of Pathology, Johns Hopkins Medical Institutions, Baltimore,
MD.
Received May 27, 2005;
accepted after revision August 2, 2005.
Supported in part by the National Institutes of Health, grants DA1277 and
DA15020.
Abstract
 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
SUBJECTS AND METHODS. Fifty consecutive CT coronary angiograms obtained on a 64-MDCT scanner were independently reviewed by two reviewers. Segments were scored as showing no motion (score of 1), minimal motion (2), moderate motion (3), respiratory motion (4), or vessel blurring (5). Opacification was graded as good (score of 1) or limited (2). Segments < 2 mm were graded as well seen; or as poorly seen or not seen. The scores for motion artifact, opacification, and visibility were combined for overall vessel assessment. Segments with a motion score of 1 or 2 that had good opacification and were well seen were judged to be assessable.
RESULTS. A total of 714 segments were analyzed in 50 patients. Seven hundred segments were assessed in all patients (segments 1-3, 11-20, 4, or 27), and a ramus intermedius segment was evaluated in 14 patients. Combining the scores for both reviewers, the average motion score was 1 for 619 segments (86.7%), the average motion score for all segments in an individual patient was 1.14 (range, 1-3.35), and the average opacification score for all segments in a patient was 1.02 (range, 1-1.38). A total of 374 segments were less than 2 mm in diameter. Combining the scores for both reviewers, an average of 36 segments (5.0% of 714) could not be identified by the reviewers, 319.5 segments (85.4%) were well seen, and 18.5 segments (4.9%) were poorly seen. Overall, an average of 637 segments (89.2%) were judged assessable by the reviewers. On a perpatient basis, 10 or more vessel segments were judged assessable in 47 patients (94%).
CONCLUSION. On 64-MDCT, 89% of coronary artery segments are assessable. Ten or more vessel segments are assessable in 94% of patients.
Keywords: angiography • cardiac imaging • coronary arteries • CT • MDCT
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
The ability to diagnose noncalcified plaque and stenosis depends on adequate visualization of the coronary arteries without motion artifact. Previously, when evaluating the sensitivity and specificity of CT for the detection of coronary artery disease, segments have been excluded because of suboptimal visualization. For vessels > 2 mm in diameter, 68-90% were judged assessable using a 4-MDCT scanner and approximately 70% were assessable with a 16-MDCT scanner [1]. The purpose of this study was to determine the diagnostic quality of images of coronary artery segments obtained on a 64-MDCT scanner.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
|
|
|
|
|
|
Scanning Protocol
The scans were obtained with retrospective ECG gating, 120 kVp, 850
effective mAs, 0.6-mm detector collimation, 0.33- to 0.37-sec gantry rotation
time, and 0.75-mm-thick slices reconstructed at 0.4-mm intervals. The scan
delay was determined by injecting a test bolus of 20 mL of contrast material,
measuring the time to peak attenuation in the ascending aorta, and adding 6
sec to that delay. Then, 80 mL of nonionic isosmolar contrast material
(Visipaque 320 [iodixanol], GE Healthcare) was injected at 4 mL/sec followed
by a 40-mL flush of saline. Ten sets of images were reconstructed through the
cardiac cycle from 0% to 90% of the R-R interval.
Image Interpretation
The images were independently evaluated by two reviewers on a workstation
to assess for quality. The reviewers were blinded to the indications for the
study. A combination of axial, multiplanar reconstruction,
maximum-intensity-projection, and volume-rendered images was used to assess
the vessels. The image set reconstructed with a relative delay of 70% was
initially viewed by both reviewers. If artifacts were noted in vessel
segments, additional reconstructions were analyzed. The score for a vessel
segment was based on the reconstruction that displayed the vessel with the
least artifact.
Vessel segments were assessed for motion artifact, quality of opacification, and visibility for segments less than 2 mm in diameter. For the assessment of motion artifact, to facilitate comparison with 16-MDCT, vessel segments were scored using the scale provided by Kuettner et al. [1]. A score of 1 indicated no motion artifact (Fig. 1), a score of 2 indicated minimal motion artifact (one stairstep artifact) (Fig. 2), a score of 3 indicated moderate motion artifact (> 1 stairstep artifact or minimal blurring of vessel edge but the vessel was assessable) (Figs. 3A and 3B), and a score of 5 indicated the vessel was blurred and could not be assessed (Figs. 4A and 4B). Respiratory motion artifact was given a score of 4. Opacification of the vessels was graded as good (score of 1) or limited (score of 2) (Figs. 5A and 5B). Vessel segments less than 2 mm were graded as well seen; or as poorly seen (Figs. 6A and 6B) or not seen.
|
|
|
|
Vessel segments were classified using the BARI (Bypass Angioplasty Revascularization Investigation) classification system [2] (Fig. 7). A total of 14 segments were analyzed per patient, with the ramus intermedius being an additional segment, if present. Note was made of vessel segments that were not seen.
|
The reviewers also noted which reconstructions of the percentage of the R-R cycle were reviewed for analyzing each vessel. The optimal reconstruction for each vessel was also recorded.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Motion and Opacification Data
The distributions of motion and opacification scores for each reviewer are
shown in Table 1. The scores
for each vessel segment for both reviewers are presented in
Table 2. For reviewer 1, the
average motion score for all segments in an individual patient was 1.15
± 0.43 (SD) (range, 1-3.35). For reviewer 2, the average motion score
for all segments in a patient was 1.14 ± 0.39 (range, 1-2.78). For
reviewer 1, the average opacification score for all segments in a patient was
1.01 ± 0.03 (range, 1-1.15). For reviewer 2, the average opacification
score for all segments in a patient was 1.04 ± 0.07 (range,
1-1.38).
|
|
Visibility of Small Vessel Segments
A total of 374 segments were less than 2 mm in diameter. Reviewer 1 graded
334 segments (89.3%) as well seen and eight segments (2.1%) as poorly seen and
this receiver could not identify 32 segments (8.5%)
(Table 3). Three hundred five
segments (81.5%) were well seen, 29 segments (7.7%) were poorly seen, and 40
segments (10.7%) could not be identified by reviewer 2.
|
Overall Assessment of Vessel Visualization
Overall assessment of the vessel segments is shown in
Table 4. Segments with a motion
score of 1 or 2 that had good opacification and were well seen were judged to
be assessable. Six hundred fifty segments (91%) were judged assessable by
reviewer 1 and 624 segments (87.3%) by reviewer 2. On a per-patient basis, all
14 segments were judged assessable in 24 patients (48%) by reviewer 1 and in
15 patients (30%) by reviewer 2 (Fig.
8). Thirteen segments were assessable in 15 patients according to
reviewer 1 and in 14 patients for reviewer 2. In these patients, the single
unassessable segment was the posterior descending artery; distal right
coronary artery (RCA); or second diagonal, distal circumflex, or first
diagonal branch. The second diagonal segment was unassessable in 11 patients
for reviewer 1 and in five patients for reviewer 2. Thirteen or more vessel
segments were assessable in 39 patients (78%) for reviewer 1 and in 29
patients (58%) for reviewer 2. Ten or more vessel segments were judged
assessable in 48 patients (96%) by reviewer 1 and in 46 patients (92%) by
reviewer 2. The proximal segments were assessable in 46 patients.
|
|
In one patient, the proximal circumflex segment was < 2 mm and was not well opacified, but the remaining proximal segments were assessable. In three patients, all proximal segments were not assessable because of motion artifact; the heart rate in those patients was 73 or 74 bpm. Of the 50 patients, there were six with a mean heart rate of > 70 bpm and the proximal segments were assessable in the other three patients.
Data on Percentages of the R-R Interval Assessed By Both Reviewers
The 70% reconstruction was judged best for assessing the coronary arteries
for most patients by both reviewers. The data are as follows: 70% was the best
for assessment of the left main coronary artery in 45 patients for both
reviewers, 70% was best for the left anterior descending (LAD) artery in 43
patients for reviewer 1 and 39 patients for reviewer 2, 70% was best for the
circumflex artery in 43 patients for reviewer 1 and 44 patients for reviewer
2, and 70% was best for the RCA in 39 patients for reviewer 1 and 35 patients
for reviewer 2.
The 70% reconstruction alone was sufficient for assessing the vessels in most patients for both reviewers. The data are as follows: the 70% reconstruction alone was used for assessing the left main artery in 40 patients, the LAD artery in 39 patients, the circumflex artery in 39 patients, and the RCA in 34 patients by reviewer 1. The 70% reconstruction alone was used for assessing the left main artery in 44 patients, the LAD artery in 36 patients, the circumflex artery in 43 patients, and the RCA in 30 patients by reviewer 2.
Comparison with 16-MDCT Article
Table 5 compares the
findings of our results with a 16-MDCT study for motion artifacts using a
similar image quality grading scale
[1]. The number of segments
with no, minor, or moderate motion artifacts and the number that appeared
blurred are shown. The blurred (motion score of 5) and poorly seen segments
are combined for comparison. In the study by Kuettner et al.
[1], 6.7% of the segments were
limited by heavy calcium, and these segments are not included in
Table 5.
|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
In other articles about the image quality of coronary 16-MDCT, Nieman et al. [3] reported 69% of vessels were well seen; 23%, adequately seen; and 7%, poorly seen. Vessels 2 mm or larger were evaluated, and the average heart rate of the patients was 56 bpm. Our study included small vessels and showed improved visibility for vessel segments. The results of our study are compared with articles in the literature in Table 6. The number of segments with no or minimal motion artifact is given as assessable, and segments limited by heavy calcification are excluded from the data in Table 6 if this information is available from the literature.
|
Previously, segments with moderate artifacts but in which the lumen could be evaluated were included as assessable; however, in our study we included only segments with no or minimal artifacts as assessable to determine the highest quality achievable with MDCT. Using this criterion, a high percentage of 85-90% of vessel segments were assessable with 64-MDCT, which is greater than the percentages of assessable vessel segments reported for studies of 16-MDCT in which similar information is available. The articles by Maruyama et al. [6] on 10 patients and by Hoffmann et al. [7] reported a high percentage of vessel segments as being assessable. However, the number of segments with no, minimal, or moderate artifacts is not specified in those studies. Our study also included segments smaller than 2 mm in diameter, which were excluded in most prior studies.
Vessel visibility with the 64-MDCT scanner is also higher than with the 4-MDCT scanner (Table 6). On axial analysis of 940 segments using 4-MDCT, Schroeder et al. [12] found that 25.9% segments were incompletely visualized. Approximately 5% of the segments in our series were not visualized. These segments may have been anatomically absent or may have been too small to visualize because of the spatial resolution of the scanner. Anatomic variation is recognized on angiography with vessels being classified as large, medium, small, or absent [2].
On a per-patient basis, all segments were assessable in 30-48% of the patients in our study. This result is similar to those reported in the literature; however, whether similar criteria were used in other studies for judging vessel segments as assessable is not known. Achenbach et al. [11] reported that in 19 (30%) of 64 patients, all arteries were assessable with 4-MDCT [11]. Similarly, Giesler et al. [13] reported all segments were assessable with 4-MDCT in 39% of patients. Ropers et al. [14] found that in 57 (74%) of 77 patients all arteries were assessable with 16-MDCT. We excluded segments with moderate artifacts from the group of segments considered to be assessable, and this may account for the similarity in our results with those obtained by researchers using 4-MDCT and 16-MDCT. Small segments, such as the second diagonal branch, distal RCA, and distal circumflex artery, accounted for most of the cases in which single segments were unassessable in patients. In more than 90% of the patients in our study, 10 or more vessel segments were assessable.
Seventy percent of the R-R interval was found to be the best reconstruction increment for assessing vessels in most patients. This finding is similar to that of a prior report in which 60% of the R-R interval was found to be the best reconstruction window for patients with a heart rate of less than 70 bpm [15].
In conclusion, on 64-MDCT, a high percentage (86-90%) of coronary artery segments are assessable with no or minimal motion artifact. These results are higher than those reported for 16- and 4-MDCT. We found that 10 or more vessel segments are assessable on 64-MDCT in 92-96% of patients.
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  A. B. Meijer, Y. L. O, J. Geleijns, and L. J. M. Kroft Meta-Analysis of 40- and 64-MDCT Angiography for Assessing Coronary Artery Stenosis Am. J. Roentgenol., December 1, 2008; 191(6): 1667 - 1675. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Matsuura, J. Horiguchi, H. Yamamoto, N. Hirai, T. Tonda, N. Kohno, and K. Ito Optimal Cardiac Phase for Coronary Artery Calcium Scoring on Single-Source 64-MDCT Scanner: Least Interscan Variability and Least Motion Artifacts Am. J. Roentgenol., June 1, 2008; 190(6): 1561 - 1568. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Tsampoulas, A. C. Tsili, D. Giannakis, Y. Alamanos, N. Sofikitis, and S. C. Efremidis 16-MDCT Cystoscopy in the Evaluation of Neoplasms of the Urinary Bladder Am. J. Roentgenol., March 1, 2008; 190(3): 729 - 735. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. T. Johnson, J. Eng, H. K. Pannu, and E. K. Fishman 64-MDCT Angiography of the Coronary Arteries: Nationwide Survey of Patient Preparation Practice Am. J. Roentgenol., March 1, 2008; 190(3): 743 - 747. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Matt, H. Scheffel, S. Leschka, T. G. Flohr, B. Marincek, P. A. Kaufmann, and H. Alkadhi Dual-Source CT Coronary Angiography: Image Quality, Mean Heart Rate, and Heart Rate Variability Am. J. Roentgenol., September 1, 2007; 189(3): 567 - 573. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. J. M. Kroft, A. de Roos, and J. Geleijns Artifacts in ECG-Synchronized MDCT Coronary Angiography Am. J. Roentgenol., September 1, 2007; 189(3): 581 - 591. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Mahesh and D. D. Cody AAPM/RSNA Physics Tutorial for Residents: Physics of Cardiac Imaging with Multiple-Row Detector CT RadioGraphics, September 1, 2007; 27(5): 1495 - 1509. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. L. Ehman, W. R. Hendee, M. J. Welch, N. R. Dunnick, L. B. Bresolin, R. L. Arenson, S. Baum, H. Hricak, and J. H. Thrall Blueprint for Imaging in Biomedical Research Radiology, July 1, 2007; 244(1): 12 - 27. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
