Radiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Published online before print June 13, 2005, 10.1148/radiol.2361040923
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
2361040923v1
236/1/112    most recent
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mahnken, A. H.
Right arrow Articles by Buecker, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mahnken, A. H.
Right arrow Articles by Buecker, A.
(Radiology 2005;236:112-117.)
© RSNA, 2005

Experimental Studies

Acute Myocardial Infarction: Assessment of Left Ventricular Function with 16–Detector Row Spiral CT versus MR Imaging—Study in Pigs1

Andreas H. Mahnken, MD, Marcus Katoh, MD, Philipp Bruners, Elmar Spuentrup, MD, Joachim E. Wildberger, MD, Rolf W. Günther, MD and Arno Buecker, MD

1 From the Department of Diagnostic Radiology, Aachen University of Technology, Pauwelsstrasse 30, D-52074 Aachen, Germany. Received May 25, 2004; revision requested August 9; revision received August 21; accepted October 5. Address correspondence to A.H.M. (e-mail: mahnken{at}rad.rwth-aachen.de).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
PURPOSE: To assess global left ventricular (LV) function and regional wall motion with retrospective electrocardiographically gated 16–detector row computed tomography (CT) in comparison with magnetic resonance (MR) imaging.

MATERIALS AND METHODS: In 15 pigs (mean weight, 53.9 kg ± 9.5 [standard deviation]), acute myocardial infarction was induced with balloon occlusion of the left anterior descending coronary artery after approval was obtained from the committee on animal affairs. Thereafter, multi–detector row CT and MR imaging were performed with standardized examination protocols. From manually drawn endocardial and epicardial contours, LV volumes, including mean ejection fraction, peak filling rate (PFR), peak ejection rate (PER), time to PER, and time from end systole to PFR, were calculated. Regional wall motion was assessed from cine loops with a 16-segment model of the left ventricle. LV function was analyzed by using Bland-Altman plots, Student t test, and Pearson correlation coefficient. Regional wall motion scores were compared with weighted {kappa} statistic.

RESULTS: LV volumes determined with multi–detector row CT correlated well with MR imaging results, with an ejection fraction of 46.1% ± 6.5 for multi–detector row CT and 46.8% ± 5.9 for MR imaging (r = 0.97). PER, PFR, time to PER, and time from end systole to PFR showed a wide range of scattering and significant differences between multi–detector row CT and MR imaging for PER and time from end systole to PFR (P < .05). Regional wall motion scores showed a very high level of agreement with a {kappa} value of 0.88.

CONCLUSION: Although 16–detector row CT allows reliable assessment of LV volumes and regional wall motion at rest, it is not suited for assessment of all functional parameters.

© RSNA, 2005


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 
Morphologic information about the coronary arteries and about left ventricular (LV) function are of substantial value for the treatment of patients with coronary artery disease. For efficient patient treatment, a comprehensive noninvasive examination is desirable to assess both coronary arteries and LV function. The capability of retrospective electrocardiographically gated multi–detector row spiral computed tomography (CT) in the acquisition of thin-section coronary angiograms has been proved, with good sensitivity and specificity for the detection of coronary artery stenosis (1,2). Assessment of LV volumes also proved feasible (3). There are no data, however, about cardiac function assessed with 16–detector row spiral CT. To the best of our knowledge, all of the published data were acquired with four–detector row spiral CT scanners. Limitations of these data are caused by a temporal resolution limited to 125–250 msec and long breath-hold periods of approximately 35 seconds (4). Although global LV function could be assessed with good correlation to results with biplane ventriculography, echocardiography, and magnetic resonance (MR) imaging (3,5,6), the capability of the latter exceeds the capability of multi–detector row CT. Thus, there is a need for improved temporal resolution and shorter scanning times for multi–detector row CT. Furthermore, there are only very limited multi–detector row CT data in regard to regional wall motion analysis, and these data suggest that multi–detector row CT wall motion analysis is limited by the temporal resolution (7).

Thus, the aim of this study was to assess global LV function and regional wall motion by using retrospective electrocardiographically gated 16–detector row CT in comparison with MR imaging.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 References
 
Animal Preparation
Fifteen domestic pigs that weighed 50 to 63 kg (mean, 53.9 kg ± 9.5 [standard deviation]) were included in this study after approval from the official committee on animal affairs. All animal experiments and imaging studies were performed by the authors (A.B., A.H.M., E.S., M.K., P.B.). The animals were premedicated with intramuscular injection of 0.5 mL atropine (Atropinum sulfuricum solution 1%; WDT, Garbsen, Germany), 0.2 mL azaperone (Stresnil; Janssen-Cilag, Neuss, Germany), and 0.1 mL ketamine (Ketamin 10%; Ceva Tiergesundheit, Düsseldorf, Germany) per kilogram body weight. Subsequently, pentobarbital solution diluted with saline in a ratio of 1:3 was administered as needed via an 18-gauge venous access catheter placed in an ear vein. No additional medication was applied to reduce the heart rate of the animals. The animals were intubated and mechanically ventilated. With fluoroscopic guidance, a 7-F guidance catheter (Vista Brite Tip; Cordis, Miami Lakes, Fla) was placed at the origin of the left coronary artery. First, a coronary angiogram was obtained to visualize the anatomy of the left coronary artery. Afterward, balloon occlusion of the left anterior descending branch of the artery was performed for 45 minutes at the midsection. The size of the balloon catheter (Hayate; Terumo, Tokyo, Japan) was individually adapted to the vessel size and ranged from 2 to 3 mm. Total occlusion was controlled by using repeated coronary angiograms. The entire procedure was performed during electrocardiographic monitoring. In case of LV fibrillation, direct current defibrillation was performed (n = 7).

Multi–Detector Row CT Examination
All CT examinations were performed with a 16–detector row CT scanner (Sensation 16, release VA 50; Siemens, Forchheim, Germany) during suspended mechanical ventilation in end expiration lasting a mean of 17.8 seconds ± 3.1. A standardized examination protocol, with 12 detector rows and 0.75-mm section thickness, 2.8-mm table feed per rotation, and a tube rotation time of 420 msec, was used. Tube voltage was 120 kV with an effective tube current–time product of 500 mAs. All multi–detector row CT scans were obtained in the craniocaudal direction. Contrast material was administered via an 18-gauge catheter in an ear vein. The scanning delay was determined with the injection of a 20-mL test bolus of the contrast agent (Ultravist 370; Schering, Berlin, Germany), with a flow rate of 4 mL/sec and repeated scanning every 2 seconds at the level of the ascending aorta. The time to peak enhancement in the ascending aorta plus 5 seconds was chosen as the delay time. For ventricular enhancement, a biphasic injection protocol with injection of 50 mL at a flow rate of 4 mL/sec, followed by injection of 30 mL at a flow rate of 3 mL/sec, was used to achieve a more homogeneous and more prolonged enhancement (8). Both injections were followed by a 30-mL saline chaser bolus injected at flow rates of 4 mL/sec and 3 mL/sec, respectively.

For image reconstruction, a bisegmental algorithm with a temporal resolution that ranged from 105 to 210 msec, depending on the heart rate, was used (9). From raw data, 20 series of transverse images were reconstructed, with one at every 5% (0%–95%) of the R-R interval, with an effective section thickness of 1.0 mm and a reconstruction increment of 0.6 mm. For each image series, a field of view of 180 x 180 mm2, a reconstruction matrix of 512 x 512, and a medium-smooth convolution kernel (B30f) were chosen. Window settings were individually adapted by using the half-contour principle as described elsewhere (10); as a result, average window center was 179 HU ± 27 and window width was 358 HU ± 39. For further analysis, 8-mm multiplanar reformations without an intersection gap were calculated along the short axis, as well as in the two-, three-, and four-chamber orientations. Multiplanar reformations were analyzed with software (Argus; Siemens) implemented on an external workstation (Leonardo; Siemens).

MR Imaging
MR imaging was performed with a 1.5-T whole-body MR imaging unit (Gyroscan Intera; Philips Medical Systems, Best, the Netherlands) by using a five-element cardiac synergy coil. All animals were examined in the supine position. A segmented-k-space steady-state free precession (also called true fast imaging with steady-state precession or balanced fast field-echo) sequence was performed by using a prospective electrocardiographic trigger technique with retrospective adjustment of the heart phases for acquisition of 25 heart phases during suspended ventilation. Imaging parameters were as follows: repetition time msec/echo time msec, 3.1/1.6; flip angle, 60°; field of view, 350 mm x 270 mm; and matrix, 256 x 152. Ten phase-encoding steps were used per time frame (views per segment); a temporal resolution of 32 msec for a heart rate of 89 beats per minute resulted. Images with a section thickness of 8 mm without an intersection gap were acquired in standardized short-axis and two-, three-, and four-chamber orientations. On average, the heart was imaged with 10 (range, nine to 11) short-axis sections. Window settings were visually adapted, depending on the individual image contrast. For analysis, the image data were transferred to an external workstation equipped with a dedicated cardiac software package (MRI-Mass; Medis, Leiden, the Netherlands).

Data Analysis
All animals underwent complete multi–detector row CT and MR imaging examinations. Multi–detector row CT and MR images were each assessed by a different reader, who was blinded to the results of the other modality. Multi–detector row CT images were evaluated by one author (A.H.M., with 5 years of experience with cardiac CT), and MR images were reviewed by another (P.B., with 2 years of experience with cardiac MR imaging). Sections from the apex to the base of the heart were obtained for quantitative assessment. The first section of the left ventricle with a visible lumen during the entire cardiac cycle was defined as the left ventricular apex, whereas the base of the left ventricle was defined as the most basal section surrounded by at least 50% myocardium in all heart phases. Papillary muscles were included with the ventricular lumen. Endocardial and epicardial borders of the left ventricle were traced manually for all cardiac phases. Motion artifacts such as stepping were thoroughly considered during manual drawing of the contours, with the contours following the outline of the artifacts. End systole was defined as maximum contraction, and end diastole, as maximum dilatation of the left ventricle (Fig 1). End-diastolic volume, end-systolic volume, stroke volume, ejection fraction, peak filling rate (PFR), peak ejection rate (PER), time to PER, and time from end systole to PFR, as well as myocardial mass, were calculated by using the Simpson method.



View larger version (89K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1a. Short-axis multiplanar reformations calculated from multi–detector row CT data of left ventricle allowed differentiation between (a) systole and (b) diastole. LV volumes were determined from manually drawn endocardial and epicardial contours by using the Simpson method. Black contour line indicates the endocardial margin, and white contour line marks the epicardial border.

 


View larger version (104K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1b. Short-axis multiplanar reformations calculated from multi–detector row CT data of left ventricle allowed differentiation between (a) systole and (b) diastole. LV volumes were determined from manually drawn endocardial and epicardial contours by using the Simpson method. Black contour line indicates the endocardial margin, and white contour line marks the epicardial border.

 
For wall motion analysis, cine loops in the short axis, as well as in the two-, three-, and four-chamber orientations were evaluated. Segmental wall motion was assessed by using a 16-segment model of the left ventricle (11). Regional wall motion of each segment was scored separately as follows: normal, hypokinetic (decreased endocardial excursion and systolic wall thickening), akinetic (absence of endocardial excursion and systolic wall thickening), and dyskinetic (paradoxical outward movement in systole).

Statistical Analysis
Continuous data were expressed as the mean ± standard deviation and were compared by using the two-tailed paired Student t test. Regional wall motion scores are expressed in a cross table. Agreement of the wall motion scores obtained with both multi–detector row CT and MR imaging was analyzed by using the weighted {kappa} statistic. According to Landis and Koch (12), the {kappa} statistic was valued as follows: 0–0.20, low; 0.21–0.40, moderate; 0.41–0.60, good; 0.61–0.80, substantial; and greater than 0.80, perfect agreement. Agreement for global LV function was determined with the Pearson correlation coefficient and Bland-Altman analysis. For all statistical testing, a P value less than .05 was considered significant. All statistics were computed by using software (MedCalc, version 7.1; MedCalc Software, Mariakerke, Belgium).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 References
 
Mean heart rate during multi–detector row CT was 88.9 beats per minute ± 12.0 (range, 72–106 beats per minute); mean temporal resolution was 152.3 msec ± 40.4. All multi–detector row CT and MR images were suitable for analysis, but multiplanar reformations from multi–detector row CT data during systole usually showed substantial motion artifacts.

Mean LV ejection fraction determined by means of multi–detector row CT was 46.1% ± 6.5, whereas MR imaging resulted in a mean ejection fraction of 46.8% ± 5.6, and these values demonstrated that there was good correlation between both techniques (r = 0.97). Comparable results were found for end-diastolic volume, end-systolic volume, stroke volume, and myocardial mass. In regard to these parameters, no significant differences were found between multi–detector row CT and MR imaging. Agreement with respect to PER, PFR, time to PER, and time from end systole to PFR was markedly worse, with significant differences between multi–detector row CT and MR imaging for PER (P = .04) and time from end systole to PFR (P = .03). The results are summarized in detail in Table 1. Bland-Altman plots that show comparisons of the different parameters of LV function are shown in Figure 2. LV time-volume curves illustrate the differences between multi–detector row CT and MR imaging for the quantitative analysis of the LV function (Fig 3).


View this table:
[in this window]
[in a new window]

  		TABLE 1. Parameters of Global LV Function Determined with Multi–Detector Row CT and MR Imaging

 


View larger version (23K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2a. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (29K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2b. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (22K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2c. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (23K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2d. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (24K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2e. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (26K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2f. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (26K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2g. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (25K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2h. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (28K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2i. Bland-Altman plots show the agreement between multi–detector row CT and MR imaging for (a) end-diastolic volume (EDV), (b) end-systolic volume (ESV), (c) stroke volume (SV), (d) ejection fraction (EF), (e) myocardial mass, (f) PER, (g) PFR, (h) time to PER (TPER), and (i) time from end systole to PFR (TPFR). Solid lines represent the mean difference, whereas the dotted lines represent the upper and lower limits of agreement. There is good agreement for end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, and myocardial mass, with mean values close to zero and clinically acceptable upper and lower limits of agreement. Results for PER, PFR, time to PER, and time from end systole to PFR were disappointing; the relevant mean difference, when compared with the reference standard, had clinically unacceptable limits of agreement.

 


View larger version (18K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 3a. Graphs show LV time-volume curves for (a) multi–detector row CT and (b) MR imaging. Although there is good agreement with respect to LV volumes, time-dependent change of LV volume differs markedly because of the limited temporal resolution of multi–detector row CT, and this finding resulted in different PER, PFR, time to PER, and time from end systole to PFR.

 


View larger version (15K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 3b. Graphs show LV time-volume curves for (a) multi–detector row CT and (b) MR imaging. Although there is good agreement with respect to LV volumes, time-dependent change of LV volume differs markedly because of the limited temporal resolution of multi–detector row CT, and this finding resulted in different PER, PFR, time to PER, and time from end systole to PFR.

 
Assessment of regional wall motion revealed that there was overall agreement in results for 217 of 240 myocardial segments (90.4%). The corresponding weighted {kappa} value of 0.88 indicated perfect agreement. Wall motion assessment results are presented in Table 2.


View this table:
[in this window]
[in a new window]

  		TABLE 2. Agreement between Multi–Detector Row CT and MR Imaging for Assessment of Regional Wall Motion

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
References
 
Ventricular function reflects the hemodynamics and the prognosis of a variety of cardiovascular diseases, especially in patients with dilated or poorly functioning ventricles (13,14). Although ventricular volumes and myocardial mass are independent predictors of morbidity and mortality in patients with coronary artery disease (15), changes in the time-volume relationship allow the early detection of filling or ejection dysfunction (16). Parameters such as PER and PFR can be used to detect progression of disease or response to therapy. Abnormalities of ventricular wall motion are important markers of myocardial ischemia (17). Different invasive and noninvasive imaging modalities for quantitative and qualitative assessment of LV performance are available, including x-ray angiography, two- and three-dimensional echocardiography, MR imaging, electron-beam CT, and electrocardiographically gated single photon emission CT (18). In the past few years, four–detector row CT was introduced for the evaluation of cardiac function (3,5,6); however, data about the new generation of 16–detector row CT scanners are lacking. Over the past decade, MR imaging became the reference standard for quantification of LV function, and its value for the measurement of regional LV wall motion was proved (19,20). Therefore, in the present study, retrospective electrocardiographically gated 16–detector row CT was compared with MR imaging for quantification of global LV function and assessment of regional wall motion.

Multi–detector row CT with a subsecond gantry rotation time has been successfully introduced for depiction of the coronary arteries, as well as for the assessment of functional parameters such as end-diastolic volume, end-systolic volume, or ejection fraction. There are no data available, however, in regard to more sophisticated time-dependent parameters such as PER and PFR. Moreover, assessment of regional wall motion was feasible with application of standard image reconstruction algorithms but limited because of temporal resolution. By using dedicated image reconstruction algorithms with optimized temporal resolution—algorithms that are used to calculate data from several gantry rotations—assessment of regional wall motion was markedly improved, whereas spatial resolution was reduced (7). Thus, these image reconstruction algorithms are not suited for evaluation of the coronary arteries, as both high spatial resolution and high temporal resolution are required. With introduction of the next generation of multi–detector row CT scanners with gantry rotation times of 420 msec or shorter and with section thickness decreased to 0.5 mm, these problems might be overcome. Although results of multi–detector row CT coronary angiography were distinctly improved with introduction of this new generation of multi–detector row CT scanners, to our knowledge, there are no data available in regard to the evaluation of LV function.

Improved spatial resolution of 16–detector row CT does not come into effect with 8-mm multiplanar reformations for the assessment of cardiac function. Nevertheless, an improvement in the evaluation of cardiac function can be expected, because temporal resolution is known to be more important than spatial resolution for the assessment of LV function (21). As was expected, results for the assessment of the LV volumes were slightly better, when compared with the data obtained at lower temporal resolution (6). Notably, these results were achieved at a relatively high heart rate, proving multi–detector row CT robust for the assessment of LV volumes. In contrast, results for the directly time-dependent parameters of PER, PFR, time to PER, and time from end systole to PFR were disappointing. These parameters show a clinically unacceptable scattering and a relevant mean difference when compared with the reference standard. Although mean temporal resolution in our study was about 152 msec and was, therefore, shorter than electromechanical systole, with about 300 msec, this finding is likely because of the limited temporal resolution. As is known from the literature, minimal LV volume is maintained for only 80–200 msec. Thus, motion-free imaging of the heart requires a temporal resolution decreased to 20 msec (22). As a consequence, there is an obvious discrepancy between cardiac motion and temporal resolution of the multi–detector row CT scanner. Hence, the latter has to become markedly improved before all of these parameters can reliably be determined with multi–detector row CT.

In the analysis of regional wall motion, our results were promising, with an excellent agreement between MR imaging and multi–detector row CT. To detect early ischemia by means of regional wall motion abnormalities, however, stress testing is required. Stress testing results in a higher heart rate and, therefore, an improved temporal resolution is required to keep motion artifacts within an acceptable range. Although regional wall motion at rest can reliably be assessed at a temporal resolution of 80–90 msec, stress testing requires a temporal resolution decreased to 40 msec (23). Functional analysis, however, usually is performed as a by-product of coronary multi–detector row CT angiography. In this respect, wall motion analysis at rest will be sufficient. Besides, multi–detector row CT stress testing would require a second exposure to radiation and a second delivery of contrast material, and these additions to the procedure are not justified, whereas noninvasive imaging techniques such as echocardiography and MR imaging are readily available. Moreover, repeated application of contrast material may be troublesome, not only with respect to renal function but also with respect to its effects on the electrocardiogram and hemodynamics (24,25). On the other hand, in patients with unfavorable conditions for echocardiography and contraindications to MR imaging because of metal implants, such as pacemakers, multi–detector row CT is an alternative.

There were several limitations of this study. Most of the animals had an elevated heart rate, which is considered unsuitable for coronary multi–detector row CT. The good results, however, even with unfavorable conditions, proved this technique reliable for the assessment of cardiac function. Because temporal resolution was limited to 105–210 msec, motion artifacts were present on systolic images. These artifacts, however, did not affect the results, as they were considered during manual drawing of the contours. None of the myocardial segments had to be excluded from analysis, but motion artifacts are likely to hamper automated contour tracing. When one interprets the data, one must consider that in all of the animals the left anterior descending branch of the left coronary artery was occluded. Furthermore, none of the infarcted segments were dyskinetic. Results are expected to get better at lower heart rates, as has been shown for coronary multi–detector row CT. Even at heart rates less than 70 beats per minute, the minimal LV volume does not last long enough to be visualized without motion artifacts, due to the limited temporal resolution of multi–detector row CT. Thus, only minor improvements will be expected at decreased heart rates.

In conclusion, 16–detector row CT allows reliable assessment of LV volumes and regional wall motion at rest but is not yet suited for the assessment of parameters that directly depend on a high temporal resolution. Further technical developments, such as shorter gantry rotation times and resultant improved temporal resolution, are likely to help overcome the present limitations of multi–detector row CT in the analysis of cardiac function.

Practical application: Clinically, the ability to accurately evaluate LV function, which includes wall motion, is important, because the prediction of morbidity and mortality in patients with coronary artery disease will be improved. Thus, retrospective electrocardiographically gated multi–detector row CT has the potential to improve the efficiency of patient treatment with the combined assessment of the coronary arteries and LV function in a single comprehensive examination.


   FOOTNOTES
 

Abbreviations: LV = left ventricular • PER = peak ejection rate • PFR = peak filling rate

See also Science to Practice in this issue

Authors stated no financial relationship to disclose.

Author contributions: Guarantor of integrity of entire study, A.H.M.; study concepts, A.H.M., A.B.; study design, A.H.M., E.S.; literature research, A.H.M.; experimental studies, A.H.M., A.B., E.S., P.B., M.K.; data acquisition, P.B., M.K.; data analysis/interpretation, P.B., E.S., A.H.M.; statistical analysis, A.H.M., A.B.; manuscript preparation, A.H.M., J.E.W.; manuscript definition of intellectual content, A.H.M., R.W.G., J.E.W.; manuscript editing, A.B., R.W.G., E.S.; manuscript revision/review, A.H.M., J.E.W., P.B.; manuscript final version approval, A.H.M., R.W.G.


   References
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 References
 

  1. Ropers D, Baum U, Pohle K, et al. Detection of coronary artery stenoses with thin-slice multi-detector row spiral computed tomography and multiplanar reconstruction. Circulation 2003; 107:664–666.[Abstract/Free Full Text]
  2. Nieman K, Cademartiri F, Lemos PA, Raaijmakers R, Pattynama PM, de Feyter PJ. Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography. Circulation 2002; 106:2051–2054.[Abstract/Free Full Text]
  3. Juergens KU, Grude M, Fallenberg EM, et al. Using ECG-gated multidetector CT to evaluate global left ventricular myocardial function in patients with coronary artery disease. AJR Am J Roentgenol 2002; 179:1545–1550.[Abstract/Free Full Text]
  4. Flohr T, Ohnesorge B. Heart rate adaptive optimization of spatial and temporal resolution for electrocardiogram-gated multislice spiral CT of the heart. J Comput Assist Tomogr 2001; 25:907–923.[CrossRef][Medline]
  5. Dirksen MS, Bax JJ, de Roos A, et al. Usefulness of dynamic multislice computed tomography of left ventricular function in unstable angina pectoris and comparison with echocardiography. Am J Cardiol 2002; 90:1157–1160.[CrossRef][Medline]
  6. Juergens KU, Grude M, Maintz D, et al. Multi–detector row CT of left ventricular function with dedicated analysis software versus MR imaging: initial experience. Radiology 2004; 230:403–410.[Abstract/Free Full Text]
  7. Mahnken AH, Spuentrup E, Niethammer M, et al. Quantitative and qualitative assessment of left ventricular volume with ECG-gated multislice spiral CT: value of different image reconstruction algorithms in comparison to MRI. Acta Radiol 2003; 44:604–611.[CrossRef][Medline]
  8. Cademartiri F, van der Lugt A, Luccichenti G, Pavone P, Krestin GP. Parameters affecting bolus geometry in CTA: a review. J Comput Assist Tomogr 2002; 26:598–607.[CrossRef][Medline]
  9. Flohr T, Bruder H, Stierstorfer K, Simon J, Schaller S, Ohnesorge B. New technical developments in multislice CT. II. Sub-millimeter 16-slice scanning and increased gantry rotation speed for cardiac imaging. Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 2002; 174:1022–1027.[Medline]
  10. Thompson BH, Stanford W. Evaluation of cardiac function with ultrafast computed tomography. Radiol Clin North Am 1994; 32:537–551.[Medline]
  11. Cerqueira MD, Weissman NJ, Dilsizian V, et al. Standardized myocardial segmentation and nomenclature for tomographic imaging of the heart: a statement for healthcare professionals from the Cardiac Imaging Committee of the Council on Clinical Cardiology of the American Heart Association. Circulation 2002; 105:539–542.[Free Full Text]
  12. Landis J, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977; 33:159–174.[CrossRef][Medline]
  13. Emond M, Mock MB, Davis KB, et al. Long-term survival of medically treated patients in the Coronary Artery Surgery Study (CASS) Registry. Circulation 1994; 90:2645–2657.[Abstract/Free Full Text]
  14. Hofmann T, Meinertz T, Kasper W, et al. Mode of death in idiopathic dilated cardiomyopathy: a multivariate analysis of prognostic determinants. Am Heart J 1988; 116:1455–1463.[CrossRef][Medline]
  15. White HD, Norris RM, Brown MA, et al. Left ventricular end-systolic volume as the major determinant of survival after recovery from myocardial infarction. Circulation 1987; 76:44–51.[Abstract/Free Full Text]
  16. Soldo SJ, Norris SL, Gober JR, Haywood LJ, Colletti PM, Terk M. MRI-derived ventricular volume curves for the assessment of left vetricular function. Magn Reson Imaging 1994; 12:711–717.[CrossRef][Medline]
  17. Lieberman AN, Weiss JL, Jugdutt BI, et al. Two-dimensional echocardiography and infarct size: relationship of regional wall motion and wall thickening to the extent of myocardial infarction in the dog. Circulation 1981; 63:739–746.[Free Full Text]
  18. Greenberg SB, Sandhu SK. Ventricular function. Radiol Clin North Am 1999; 37:341–359.[CrossRef][Medline]
  19. Peshock RM, Willett DL, Sayad DE, et al. Quantitative MR imaging of the heart. Magn Reson Imaging Clin N Am 1996; 4:287–305.[Medline]
  20. Sechtem U, Pflugfelder P, Higgins CB. Quantification of cardiac function by conventional and cine magnetic resonance imaging. Cardiovasc Intervent Radiol 1987; 10:365–373.[Medline]
  21. Miller S, Simonetti OP, Carr J, Kramer U, Finn JP. MR imaging of the heart with cine true fast imaging with steady-state precession: influence of spatial and temporal resolutions on left ventricular functional parameters. Radiology 2002; 223:263–269.[Abstract/Free Full Text]
  22. Ritchie CJ, Godwin JD, Crawford CR, et al. Minimum scan speeds for suppression of motion artifacts in CT. Radiology 1992; 185:37–42.[Abstract/Free Full Text]
  23. Setser RM, Fischer SE, Lorenz CH. Quantification of left ventricular function with magnetic resonance images acquired in real time. J Magn Reson Imaging 2000; 12:430–438.[CrossRef][Medline]
  24. Mancini GB, Bloomquist JN, Bhargava V, et al. Hemodynamic and electrocardiographic effects in man of a new nonionic contrast agent (iohexol): advantages over standard ionic agents. Am J Cardiol 1983; 51:1218–1222.[CrossRef][Medline]
  25. Bettmann MA, Higgins CB. Comparison of an ionic with a nonionic contrast agent for cardiac angiography: results of a multicenter trial. Invest Radiol 1985; 20(suppl 1):S70–S74.[Medline]



This article has been cited by other articles:


Home page
 CirculationHome page
D. A. Bluemke, S. Achenbach, M. Budoff, T. C. Gerber, B. Gersh, L. D. Hillis, W. G. Hundley, W. J. Manning, B. F. Printz, M. Stuber, et al.
Noninvasive Coronary Artery Imaging: Magnetic Resonance Angiography and Multidetector Computed Tomography Angiography: A Scientific Statement From the American Heart Association Committee on Cardiovascular Imaging and Intervention of the Council on Cardiovascular Radiology and Intervention, and the Councils on Clinical Cardiology and Cardiovascular Disease in the Young
Circulation, July 29, 2008; 118(5): 586 - 606.
[Full Text] [PDF]

Home page
 Br. J. Radiol.Home page
H DOGAN, W J H VELDKAMP, P DIBBETS-SCHNEIDER, A M SPIJKERBOER, B J A MERTENS, L J M KROFT, A DE ROOS, and J GELEIJNS
Effects of heart rate, filling and slice thickness on the accuracy of left ventricular volume measurements in a dynamic cardiac phantom using ECG-gated MDCT
Br. J. Radiol., July 1, 2008; 81(967): 577 - 582.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Roentgenol.Home page
C. Plumhans, G. Muhlenbruch, A. Rapaee, K.-H. Sim, T. Seyfarth, R. W. Gunther, and A. H. Mahnken
Assessment of Global Right Ventricular Function on 64-MDCT Compared with MRI
Am. J. Roentgenol., May 1, 2008; 190(5): 1358 - 1361.
[Abstract] [Full Text] [PDF]

Home page
 RadiologyHome page
K. Nieman, M. D. Shapiro, M. Ferencik, C. H. Nomura, S. Abbara, U. Hoffmann, H. K. Gold, I.-K. Jang, T. J. Brady, and R. C. Cury
Reperfused Myocardial Infarction: Contrast-enhanced 64-Section CT in Comparison to MR Imaging
Radiology, April 1, 2008; 247(1): 49 - 56.
[Abstract] [Full Text] [PDF]

Home page
 RadiologyHome page
H. Wen, K. A. Marsolo, E. E. Bennett, K. S. Kutten, R. P. Lewis, D. B. Lipps, N. D. Epstein, J. F. Plehn, and P. Croisille
Adaptive Postprocessing Techniques for Myocardial Tissue Tracking with Displacement-encoded MR Imaging
Radiology, January 1, 2008; 246(1): 229 - 240.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Roentgenol.Home page
H. Brodoefel, U. Kramer, A. Reimann, C. Burgstahler, S. Schroeder, A. Kopp, and M. Heuschmid
Dual-Source CT with Improved Temporal Resolution in Assessment of Left Ventricular Function: A Pilot Study
Am. J. Roentgenol., November 1, 2007; 189(5): 1064 - 1070.
[Abstract] [Full Text] [PDF]

Home page
 CirculationHome page
L. Sugeng, V. Mor-Avi, L. Weinert, J. Niel, C. Ebner, R. Steringer-Mascherbauer, F. Schmidt, C. Galuschky, G. Schummers, R. M. Lang, et al.
Quantitative Assessment of Left Ventricular Size and Function: Side-by-Side Comparison of Real-Time Three-Dimensional Echocardiography and Computed Tomography With Magnetic Resonance Reference
Circulation, August 15, 2006; 114(7): 654 - 661.
[Abstract] [Full Text] [PDF]

Home page
 RadiologyHome page
P. K. Woodard
Can Multi-Detector Row Spiral CT Be Used to Assess Left Ventricular Function?
Radiology, July 1, 2005; 236(1): 1 - 2.
[Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
2361040923v1
236/1/112    most recent
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mahnken, A. H.
Right arrow Articles by Buecker, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mahnken, A. H.
Right arrow Articles by Buecker, A.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
RADIOLOGY RADIOGRAPHICS RSNA JOURNALS ONLINE