Imaging plane is oriented along the center line of the coronary arteries
and superimposed with a 4.5-mm maximum-intensity projection. Arrowhead indicates
ostial calcified plaque.
A 74-year-old woman referred for multislice computed tomography (MSCT)
3 years after percutaneous coronary intervention with stent placement in the
proximal left anterior descending artery. The stent segment was primarily
excluded from further analysis and does not appear here. A, Curved multiplanar
reformation image along the right coronary artery (RCA). Ostial calcified
plaque (arrowhead) does not induce lumen narrowing. B, Conventional invasive
coronary angiogram confirms that no high-grade lesions are discernible. The
angiogram shows more side branches compared with tomography, due to both higher
in-plane spatial resolution and a more comprehensive projection. LAO indicates
left anterior oblique.
A, Multislice computed tomography (MSCT) in a 62-year-old man referred
for MSCT for suspected coronary artery disease. The MSCT image renders corresponding
lesion sites discernible (arrowheads correspond to locations in panel B).
In addition, the MSCT image shows soft plaques (ie, dark, hypodense areas
reflecting lipid or fibrous composition) causing both the indentation and
the stenotic lumen narrowing. B, Conventional invasive coronary angiogram
showing high-grade stenosis (yellow arrowhead) in the descending portion of
the right coronary artery (RCA), preceded by an indentation (black arrowhead)
that supposedly is plaque-related. C, MSCT in a 61-year-old man referred for
MSCT imaging for suspected coronary artery disease. The MSCT image shows that
the lumen obstruction in the left anterior descending (LAD) artery is caused
by fibrocalcific plaque (black arrowhead) with an inner fibrotic (hypodense)
and an outer calcific (hyperdense) layer. The indentation as shown in panel
D is caused by calcified plaque (yellow arrowhead). D, Conventional invasive
coronary angiogram showing high-grade lumen narrowing in the proximal LAD
(black arrowhead). After the branching point of the first septal perforator,
another indentation (yellow arrowhead) is discernible. LAO indicates left
A, Multislice computed tomography (MSCT) in a 68-year-old man referred
for MSCT imaging for suspected coronary artery disease. The MSCT findings
represent a typical false-positive reading. Specifically, the MSCT image shows
plaque located on the main left circumflex artery (LCX; arrowhead) in the
atrioventricular groove. Subjective and objective assessment identified significant
lumen narrowing. B, Conventional invasive coronary angiogram showing the lumen
indentation caused by plaque impingement (arrowhead). However, quantitative
coronary angiography did not identify significant (>50%) lumen narrowing.
AP indicates anterior-posterior.
Dashed lines indicate 95% confidence limits; bold line, bias.
Hoffmann MHK, Shi H, Schmitz BL, Schmid FT, Lieberknecht M, Schulze R, Ludwig B, Kroschel U, Jahnke N, Haerer W, Brambs H, Aschoff AJ. Noninvasive Coronary Angiography With Multislice Computed Tomography. JAMA. 2005;293(20):2471-2478. doi:10.1001/jama.293.20.2471
Author Affiliations: Department of Diagnostic
Radiology, University Hospital, Ulm, Germany (Drs Hoffmann, Shi, Schmitz,
Schmid, Brambs, and Aschoff); and Department of Cardiology, Heart-Center,
Ulm (Drs Lieberknecht, Schulze, Ludwig, Kroschel, Jahnke, and Haerer).
Context Multislice computed tomography (MSCT) has recently evolved as a modality
for noninvasive coronary imaging.
Objective To assess the accuracy and robustness of MSCT vs the criterion standard
of invasive coronary angiography for detection of obstructive coronary artery
Design, Setting, and Patients Prospective, single-center study conducted in a referral center setting
in Germany and enrolling 103 consecutive patients (mean age, 61.5 [SD, 9.7]
years) from November 2003–August 2004 who were undergoing both invasive
coronary angiography and MSCT using a scanner with 16 detector rows.
Main Outcome Measures Blinded results for both modalities compared using the patient as the
primary unit of analysis, with supplementary segment- and vessel-based analyses.
Results One thousand three hundred eighty-four segments (≥1.5 mm diameter)
were identified by invasive coronary angiography; nondiagnostic image quality
of MSCT was identified for only 88 (6.4%) of these segments, mainly due to
faster heart rates. Compared with invasive coronary angiography for detection
of significant lesions (>50% stenosis), segment-based sensitivity, specificity,
and positive and negative predictive values of MSCT were 95%, 98%, 87%, and
99%, respectively. Quantitative comparison of MSCT and invasive coronary angiography
showed good correlation (r = 0.87, P<.001), with MSCT systematically measuring greater-percentage
stenoses (bias, +12%). In the patient-based analysis, the area under the receiver
operating characteristic curve was 0.97 (95% confidence interval, 0.90-1.00),
indicating high discriminative power to identify patients who might be candidates
for revascularization (>50% left main artery stenosis and/or >70% stenosis
in any other epicardial vessel). Threshold optimization allowed either detection
of these patients with 100% sensitivity at a reasonable false-positive rate
(specificity, 76.5%; MSCT stenosis, >66%) or optimization of both the sensitivity
and specificity (>90%; MSCT stenosis, >76%).
Conclusions Multislice computed tomography provides high accuracy for noninvasive
detection of suspected obstructive coronary artery disease. This promising
technology has potential to complement diagnostic invasive coronary angiography
in routine clinical care.
Conventional invasive coronary angiography is currently the diagnostic
criterion standard for clinical evaluation of known or suspected coronary
artery disease (CAD). The risk of adverse events is small, but serious and
potentially life-threatening sequelae may occur, including arrhythmia, stroke,
coronary artery dissection, and access site bleeding (total complication rate,
1.8%; mortality rate, 0.1%).1,2 Furthermore,
catheterization induces some discomfort and mandates routine follow-up care.
Therefore, conventional invasive diagnostic angiography should be restricted
to stringent clinical indications.1 This situation
constitutes the basis of the demand for a reliable gatekeeper or even noninvasive
One recently developed modality that may potentially complement invasive
coronary angiography is multislice computed tomography (MSCT), which may achieve
a high level of reliability and accuracy in the visualization of the coronary
tree.3- 6 This
modality obviates much of the risk and discomfort associated with catheterization,
although it retains the risks inherent in radiation exposure and use of contrast
Past studies have tested the sensitivity and specificity of MSCT vs
invasive coronary angiography based on vessel segments and have suggested
that MSCT is highly accurate.3- 6 However,
before routine clinical application can be advocated, it is important to evaluate
predictive measures on a patient-based level rather than simply on vessel-
or segment-based levels.
One shortcoming of current cardiac computed tomography (CT) is limited
temporal resolution. Recent evolutions of the scanner technology for MSCT
imaging have made scanners with 16 detector rows widely available.7 These scanners allow noninvasive coverage of the coronary
tree within a single breath-hold of less than 25 seconds.8 Coronary
tree images free of motion artifacts are available only in quiescent low-motion
phases of the cardiac cycle.6,9 The
duration of these phases is inversely related to heart rate, and all studies
performed to date rely on heart rate reduction induced by β-blockers.3- 5,10 For
this study we used a commercially available scanner platform that offers increased
temporal resolution incorporated in a 3-dimensional volume-oriented reconstruction
resolution is enhanced by combining the projection data from consecutive heart
cycles,6,11 which may overcome
the need to lower heart rate to below 65/min.13
We therefore sought to assess the diagnostic accuracy of 16-slice MSCT
scanning in a large cohort of patients with known or suspected CAD. In addition,
we investigated how the newer MSCT technology performs in the setting of faster
From November 2003–August 2004, we enrolled 103 consecutive patients
primarily with suspected CAD who were referred for conventional invasive coronary
angiography. All were in sinus rhythm and able to sustain a 25-second breath-hold
(tested during rehearsal on a gurney). Exclusion criteria included contraindications
to iodinated contrast (ie, known allergy), renal dysfunction (serum creatinine
level >1.36 mg/dL [120 μmol/L]), hyperthyroidism (thyrotropin level <0.44
mIU/L), prior surgical revascularization, and acute coronary syndrome. The
pretest probability for CAD was assessed according to American College of
Cardiology/American Heart Association guidelines based on age, sex, and symptoms.14 The institutional review board of the University
of Ulm approved the study, and written informed consent was obtained from
Patients were connected to an electrocardiographic monitor prior to
scan initiation, and their resting heart rate was monitored for 1 minute.
If the resting heart rate during that period was 75/min or greater, intravenous
metoprolol was administered up to a maximum dose of 20 mg.
A qualitative evaluation was performed to assess the accuracy of MSCT
to detect significant lumen narrowing (defined as >50% diameter stenosis).
In addition, quantitative coronary angiography (QCA) percentage measurements
were compared with stenosis measurements generated by MSCT for culprit lesions
in each patient. A supplementary segment- and vessel-based evaluation was
conducted for comparison with previous work. The primary unit of analysis
was the patient for both qualitative and quantitative approaches. Our secondary
objective was to test the dependence of coronary segment image quality on
heart rate during image acquisition.
Imaging data were processed with observers encoding one modality blinded
to the results of the other. Conventional invasive coronary angiography and
MSCT images were evaluated for the occurrence of greater than 50% lumen obstruction
and encoded on a segmental basis. Deviating segment assignments were settled
by adjudication of a reader uninvolved in the blinded analysis. After side-by-side
comparison of the modalities, this reader was allowed to reassign MSCT segment
measurements to the next adjacent neighbor without crossing vessel borders
(one exception was defined for the intermediate branch, which could be reclassified
as both the first diagonal or the obtuse marginal branch). However, applying
changes to actual stenosis readings was not permitted. Stent-bearing segments
were excluded because beam-hardening artifacts and partial volume effects
impede reliable visualization of the coronary lumen. Segments with a diameter
of 1.5 mm or greater, as defined on conventional invasive angiograms by QCA,
For vessel-based analyses, the segments of 1 vessel branch were combined.
The coronary tree was separated into the left main artery, left anterior descending
artery, left circumflex artery (LCX), and right coronary artery (RCA). Vessels
with single segment exclusions were marked as excluded for vessel-based analysis.
Vessels with 1 or more obstructed segments were encoded as stenotic for comparison.
Patient-based analyses were conducted in 2 ways: including all patients
regardless of segment or vessel exclusions, and excluding patients with partial
coronary tree coverage due to 1 or more segments with low image quality.
For both approaches, true negative was defined as correct identification
by MSCT of patients without disease. True-positive readings included all patients
with at least 1 matched reading in any vessel regardless of correct classification
as single-vessel or multivessel disease. False-positive and false-negative
classifications were defined correspondingly with stenosis detection occurring
in only one modality and unmatched readings in the other. The underlying concept
to be tested was that a single positive MSCT reading would require referral
to invasive coronary angiography, whereas a single false-negative reading
on MSCT spoiled the accuracy potential.
In addition to the qualitative analysis, a culprit lesion was defined
for each patient (highest percentage obstruction on QCA). Quantitative percentage
stenosis estimates of the culprit lesion generated by QCA and quantitative
CT measurements were compared.
Patients were placed in a supine position for MSCT examinations using
a scanner with 16 detector rows (Brilliance 16, Philips Medical Systems, Cleveland,
Ohio). Studies were preceded by scout acquisition. Test-bolus tracking was
applied for precise timing of contrast injection. For acquisition of the helical
scan, 1.2 mL per kg of body weight of iodinated contrast agent was administered
followed by a 50-mL saline flush. The contrast flow rate was adapted according
to the test-bolus acquisition (mean flow rate, 4 mL/s). An electrocardiogram
was recorded during the continuous acquisition of CT data.
A 16 × 0.75–mm collimation scan protocol was applied
at variable pitch settings of 0.2 to 0.3 (rotation time, 420 ms). Pitch settings
defined the table feed that transported patients through the gantry during
helical image acquisition.15,16 Settings
were modified according to mean heart rate over at least 10 beats directly
prior to scan initiation. A pitch value of 0.2 was used for heart rate less
than 65/min, 0.24 for heart rate 65/min through 74/min, and 0.3 for heart
rate of 75/min or more. A tube voltage of 120 to 140 kV and a current of 190
to 300 mA were applied according to the patient’s body weight. The average
radiation dose applied for a typical patient was 8.1 mSv (tube current modulation
off; 120 kV; 240 mA; patient weight, 75 kg; pitch, 0.2; scan length, 12 cm).
Prospectively triggered x-ray tube current modulation centered around mid-diastolic
cardiac cycle phases (75% of the R-R interval) was applied for all patients
with a heart rate less than 65/min, resulting in a dose exposure of approximately
4.9 mSv (reduction dependent on heart rate). Depending on cardiac dimensions
and pitch, the scan time varied between 16.6 and 24.5 seconds.
To obtain motion-free images, standard reconstruction windows were centered
around mid-diastole (70%-80%, in 5% steps) for low heart rates (<65/min).
For patients with higher heart rates (≥65/min), additional reconstruction
windows were centered in end-systole (45%-60%, in 5% steps). A reconstruction
algorithm encompassed 3-dimensional cone-corrected back-projection in combination
with adaptive multicycle enhancements of temporal resolution, as described
images were reconstructed using a smooth-tissue filter kernel. The best cardiac
phase reconstruction for further comparative analysis was determined in a
side-by-side comparison of all phases.6 Phase
selection was performed by 2 observers in consensus attempting continuous
coronary vessel delineation without any stair-step artifacts and no blurring
of vessel border definition.
Each individual coronary segment was assessed for appropriate diagnostic
image quality. Three types of artifacts were identified: residual motion (caused
by both respiratory and cardiac motion); partial-volume averaging of high-density
objects, eg, calcified coronary plaques; and faint contrast opacification.
Both beam hardening and partial-volume averaging resulted in oversizing of
the artifact-producing object,8 which may obstruct
the adjacent coronary lumen and compromise assessment of lumen patency.8 Residual motion became apparent either as an artificial
lumen obstruction, which tended to be assessed as a false-positive reading,
or as blurring of the vessel borders, which may prevent plaque detection,
thereby resulting in false-negative readings.
Reading of MSCT images was conducted on maximum-intensity projections
oriented in multiple viewing directions. They were supplemented by volume
renderings and curved multiplanar reformation images with a center line threaded
through the coronary arteries (Figure 1).
Electronic calipers were used to measure coronary lumen diameter, which allowed
percentage quantification of obstructive lesions according to the same standards
as those applied in QCA.19
Conventional selective invasive coronary angiography images were acquired
using standard techniques. The mean (SD) interval between the MSCT scan and
conventional coronary angiography was 16.3 (15.1) days. Coronary arteries
were divided into segments according to American Heart Association classifications.20 Angiograms were evaluated by 2 readers blinded to
the results of MSCT imaging. The percentage of lumen reduction of stenotic
lesion sites was quantified using standard QCAPlus version 03.10.30 (Sanders
Data Systems, Palo Alto, Calif).
Sample size was determined by power analysis for a single proportion.21 We hypothesized that MSCT should detect greater than
50% lumen narrowing, with a sensitivity of 80% or greater. The sample size
was calculated for a power level of greater than 90%, an α error of
.05, and an expected sensitivity of 92% or greater based on previous reports.
Accuracy parameters are presented with 95% confidence intervals (CIs)
based on binomial distributions. Quantitative percentage stenosis gradings
were compared using Pearson correlation and Bland-Altman plots.22 The
area under the receiver operating characteristic (ROC) curve (AUC) was calculated
for MSCT to detect obstructive lesions.23 Calculation
was conducted at various thresholds defined by QCA (50%, 60%, and 70%). A
QCA threshold that might indicate need for revascularization was defined as
left main artery stenosis greater than 50%, lesions greater than 70% of any
other epicardial vessel, or both. The corresponding ROC analysis was conducted
for the whole group as well as for the subgroup of patients who were primarily
evaluated for suspected CAD. The AUC values for both analyses were compared
to rule out substantial confounding effects induced by the inclusion of patients
who had undergone percutaneous coronary intervention. The ROC curves were
used to optimize the CT thresholds for highest sensitivity and optimal values
of both accuracy parameters.
The association between heart rate and image quality was evaluated by
comparing segment inclusion rates after stratification over increasing heart
rate in 4 different groups. The segment inclusion rate within the 4 groups
was compared using a 2-tailed χ2 test. Statistics were computed
using SAS version 9.1 (SAS Institute Inc, Cary, NC) and Excel-based ROC tools
(Acomed, Leipzig, Germany).
A total of 128 patients were evaluated for enrollment; patients with
a postsurgical revascularization status (n = 17), multiple premature
ventricular contractions (n = 2), inability to sustain a 25-second
breath-hold (n = 2), known allergy to iodinated contrast agents
(n = 3), and hyperthyroidism (n = 1) were excluded. For
the final sample size (N = 103), the achieved power was 93.2%. Characteristics
of enrolled patients are summarized in Table 1.
The mean (SD) heart rate during scanning was 68.7 (11.6)/min (range,
45-111/min). Prospectively triggered tube current modulation was applied in
46 patients (44.7%).
Segment adjudication was applied for 23 (22%) of the patients (descending
RCA, n = 9; intermediate branch, n = 7; LCX branches,
n = 5; left anterior descending branches, n = 2). Unresolved
cases were either counted in the appropriate false-positive or false-negative
categories (following sections), prospectively excluded due to low image quality
on MSCT analysis, or excluded due to failing standard of reference for patients
with coronary anomalies (n = 3). For the latter, insufficient contrast
opacification due to failed selective cannulation was apparent on invasive
coronary angiography films (RCA, n = 2; LCX, n = 1). Disease
prevalence identified by invasive coronary angiography (stenosis >50%) was
One thousand three hundred eighty-four segments, each with a diameter
of 1.5 mm or greater, were identified, resulting in 13.4 (SD, 2.2) segments
for analysis per patient. Nondiagnostic image quality was identified in 88
(6.4%) of these segments, with image quality compromised by residual motion
artifacts in the majority of cases (60 [68%]). Extensive coronary wall calcifications
(17 [19%]) and low-vessel lumen opacifications (11 [13%]) were less apparent
in this group. Motion artifacts were most frequently located in the mid RCA
(n = 34) and increased significantly at higher heart rates (Table 2). Five segments deemed not assessable
by MSCT (severe calcifications [n = 4] or motion artifacts [n = 1,
proximal RCA]) showed significant obstructions on invasive coronary angiography
films. These segments were prospectively judged not assessable and hence these
patients were excluded without corruption of the potential accuracy of MSCT.
Parameters calculated on a segmental basis are shown in Table 3. A sample case without stenosis is presented in Figure 2. Cases with matched positive readings
are presented in Figure 3.
Eight segments were classified as false-negative. They were located
in the LCX (n = 5) or its side branches (n = 2). A false-negative
reading located in the posterior descending artery (n = 1) was related
to insufficient contrast opacification.
A total of 22 false-positive classifications occurred. They were related
to severe vessel wall calcifications (n = 7) and residual motion
(n = 15 [mid-RCA, n = 12; LCX, n = 3]). For
the lesions with vessel wall calcifications, conventional invasive angiography
revealed only minor wall irregularities or insignificant indentations (Figure 4).
The accuracy parameters for vessel-based evaluation are summarized in Table 3. All significant left main coronary artery
obstructions (n = 4) were correctly identified by MSCT. All vessel
occlusions (n = 21) were correctly detected on MSCT scans. Fifty-eight
of the 403 assessable vessels (14.4%) had partial segments excluded due to
artifacts (Table 2 and Table 3).
The accuracy parameters for patient-based evaluation are summarized
in Table 3. Excluding the 28 patients
(27%) with partial coronary tree coverage improved specificity. Multislice
CT correctly identified 38 of the 45 patients (84%) without significant stenoses
demonstrated by conventional invasive angiography. Two of 58 patients with
CAD (3.4%) were not detected by MSCT. One proximal lesion in the posterior
descending artery and 1 diagonal branch lesion were missed by MSCT due to
inadequate opacification. Patients with single-vessel disease demonstrated
by invasive coronary angiography (n = 22) were either correctly
classified (15 [68%]) by MSCT or were misclassified as having multivessel
disease (5 [23%]). Thirty patients with multivessel disease were correctly
classified by MSCT, while the remaining 6 were classified as having single-vessel
Quantitative comparison of stenosis grading using MSCT and invasive
coronary angiography showed good correlation (r = 0.87, P<.001). Bland-Altman analysis revealed that CT measured
a greater percentage of stenoses (bias, +12%; limits of agreement, −19%
to +43%) (Figure 5). The AUC for identification
of patients with stenoses eligible for revascularization was 0.97 (95% CI,
0.91-1.00; complete study cohort). Conducting the same analysis after exclusion
of patients who had undergone percutaneous coronary intervention rendered
the same AUC value of 0.97, with minimal widening of the confidence bounds
(95% CI, 0.90-1.00). Applying QCA stenosis thresholds of greater than 50%,
greater than 60%, and greater than 70% resulted in AUC values of 0.97 (95%
CI, 0.91-0.99), 0.92 (95% CI, 0.84-0.96), and 0.97 (95% CI, 0.92-1.00), respectively.
Threshold optimization for identifying patients appropriate for revascularization
occurred at greater than 66% of MSCT stenosis quantification (100% sensitivity,
76.5% specificity). Optimization of both parameters occurred at greater than
76% MSCT stenosis grading (91.4% sensitivity, 91.2% specificity).
We found that, compared with invasive coronary angiography, MSCT has
a high discriminative power to detect obstructive CAD. This is not only shown
for the detection of the standard definition of significant disease, defined
as greater than 50% lumen narrowing of the coronary artery,2 but
also at other thresholds. The discriminative power of MSCT is high for identification
of patients who are appropriate candidates for revascularization, ie, those
with greater than 50% left main artery disease, greater than 70% stenosis
in other epicardial vessels, or both. Threshold optimization showed that MSCT
could detect these patients either with 100% sensitivity, at a false-positive
rate still within reasonable limits, or that both sensitivity and specificity
could be optimized beyond 90%.
Correlation of the percentage of lumen quantification for MSCT and QCA
was high, with MSCT systematically suggesting higher values. While the limits
of agreement for this comparison appeared high at first consideration (−20%
to 40%), they must be seen in perspective with the intramodality variability
of invasive coronary angiography (−15% to 21%).19
Because ROC analysis is independent of disease prevalence,23 results
generated for our study cohort with an intermediate to high prevalence of
disease may well be applicable to lower-risk populations. Therefore, MSCT
using scanners with 16 detector rows has the potential to be routinely applied
for identifying patients who, while suspect, are unlikely to have clinically
significant disease. Our findings are consistent with multiple single-center
studies showing consistently high accuracy and negative predictive values.3- 5,10,24 The
indication is limited by false-positive rates that consecutively reduce specificity
and positive predictive value.
Multislice CT has the potential to become a valuable complement to invasive
diagnostic angiography, but ideally a reliable visualization of the complete
coronary tree is required. While only 6.4% of the coronary segments showed
low diagnostic image quality, consistent with findings from other studies
segmental exclusion rates are based on clustered evaluations.25 Segment-based
exclusions due to low image quality correlated with 14% and 27% exclusion
rates on vessel- and patient-based levels. Arguably only the patient-based
level is clinically relevant. Because diagnostic decisions based on MSCT were
derived from incomplete coronary tree coverage in 27% of our patients, this
technology is not yet ready to challenge invasive coronary angiography as
a true alternative. However, if the results generated with prior generations
of CT scanners (4 detector rows, 32% exclusion rate26)
are extrapolated beyond the current generation (16 detector rows, 7% exclusion
rate) to the scanner generation that is currently being introduced for clinical
evaluation (up to 64 detector rows), reliability may increase very rapidly
in the near future. The striking relationship of the number of detector rows
to the reliability of image quality conveys a simplification that does not
account for very important technical aspects of cardiac CT imaging.
Clinical data show that the standard currently available temporal resolution
is not sufficient to cover the normal range of resting heart rates.6,13,27 This deficiency is
corrected with β-blocker–induced heart rate reduction,13,27 which prolongs diastole and extends
the phases of low cardiac and subsequent coronary motion to allow artifact-free
imaging.6,28 Two strategies have
emerged to increase temporal resolution. The first strategy is based on faster
gantry rotation. The reconstruction of 1 CT frame depends on a 180° turn
of the gantry; thus, temporal resolution increases linearly with shortening
of the gantry rotation times.29 The second
strategy, supported by our current data, is based on shortening the reconstruction
window within a single heart cycle by segmenting the acquisition of image
data over multiple heartbeats.12 An adaptive
multicycle reconstruction approach combines data from consecutive cardiac
cycles and enhances temporal resolution to an average of 140 ms.6,11
Spatial resolution of MSCT is now in the submillimeter range but still
does not match that of invasive coronary angiography.30 This
study shows a reasonable correlation of quantitative measures acquired with
the 2 modalities. Further improvements are needed for accurate delineation
of the coronary lumen adjacent to high-density objects such as calcified plaque
or stent struts.26 Such high-density objects
extend beyond their true size into neighboring volume voxels on MSCT images.
This problem may be alleviated by decreasing voxel size or increasing spatial
resolution. However, with detector technology currently available, spatial
resolution is dose-limited. Increasing spatial resolution requires multiplication
of the radiation dose by a power of 4 to keep image noise constant.31
In conclusion, we found that MSCT shows reasonably high accuracy for
detecting significant obstructive CAD when assessed at a patient level. At
its current stage of development, it may therefore be used to substantially
reduce likelihood of clinically important CAD in patients with suspected disease.
The appeal of MSCT compared with conventional coronary angiography is that
it is noninvasive, avoiding most catheter-associated risks and discomforts
with the exception of exposure to iodinated contrast agents and radiation.
With rapidly improving technology, MSCT may well evolve from a useful complement
to invasive angiography to a clinically viable alternative.32
Corresponding Author: Martin H. K. Hoffmann,
MD, Department of Diagnostic Radiology, University Hospital, Safranberg, Steinhoevelstrasse
9, D 89070 Ulm, Germany (email@example.com).
Author Contributions: Dr Hoffmann had full
access to all of the data in the study and takes responsibility for the integrity
of the data and the accuracy of the data analysis.
Study concept and design: Hoffman, Schmitz,
Acquisition of data: Hoffman, Shi, Schmid,
Lieberknecht, Schulze, Ludwig, Kroschel, Jahnke, Haerer.
Analysis and interpretation of data: Hoffman,
Shi, Lieberknecht, Schulze, Ludwig, Kroschel, Jahnke, Haerer, Aschoff.
Drafting of the manuscript: Hoffman, Shi, Schmid,
Critical revision of the manuscript for important
intellectual content: Hoffman, Schmitz, Lieberknecht, Schulze, Ludwig,
Kroschel, Jahnke, Haerer, Brambs.
Statistical analysis: Hoffman, Shi, Lieberknecht.
Obtained funding: Brambs.
Administrative, technical, or material support:
Hoffman, Schmid, Lieberknecht, Haerer, Aschoff.
Study supervision: Hoffman, Lieberknecht, Aschoff.
Financial Disclosures: None reported.
Funding/Support: This study was funded by the
State Government of Baden-Wuerttemberg, Germany. The computed tomography equipment
was partially provided by Philips Medical Systems, Best, the Netherlands,
on the basis of a beta-site contract.
Role of Sponsor: Neither the State Government
of Baden-Wuerttemberg nor Philips Medical Systems had any involvement in the
design or conduct of this study; data management and analysis; or manuscript
preparation and review or authorization for submission.
Acknowledgment: We thank Bonnie Hami, MA, of
the Department of Radiology, University Hospitals of Cleveland, Cleveland,
Ohio, for her editorial assistance in the preparation of the manuscript.