Diagnostic value of cardiac 64-slice computed tomography: importance of coronary calcium

Serial fractional flow reserve, coronary flow reserve and index of microcirculatory resistance after percutaneous coronary intervention in patients treated for stable angina pectoris assessed with PET

BACKGROUND

Cardiac 15 O-water PET is a noninvasive method to evaluate epicardial and microvascular dysfunction and further quantitate absolute myocardial blood flow (MBF).

AIM

The aim of this study was to assess the impact of revascularization on MBF and myocardial flow reserve (MFR) assessed with 15 O-water PET and invasive flow and pressure measurements.

METHODS

In 21 patients with single-vessel disease referred for percutaneous coronary intervention (PCI), serial PET perfusion imaging and fractional flow reserve (FFR), coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) were performed during PCI and after 3 months.

RESULTS

In the affected myocardium, stress MBF and MFR increased significantly from before revascularization to 3 months after revascularization: stress MBF 2.4 ± 0.8 vs. 3.2 ± 0.8; P  < 0.001 and MFR 2.5 ± 0.8 vs. 3.4 ± 1.1; P  = 0.004. FFR and CFR increased significantly from baseline to after revascularization and remained stable from after revascularization to 3-month follow-up: FFR 0.64 ± 0.20 vs. 0.91 ± 0.06 vs. 0.91 ± 0.07; P  < 0.001; CFR 2.4 ± 1.2 vs. 3.6 ± 1.9 vs. 3.6 ± 1.9; P  < 0.001, whereas IMR did not change significantly: 30.3 ± 22.9 vs. 30.1 ± 25.3 vs. 31.9 ± 25.2; P  = ns. After revascularization, an increase in stress MBF was associated with an increase in FFR ( r  = 0.732; P  < 0.001) and an increase in MFR ( r  = 0.499; P  = 0.021). IMR measured before PCI was inversely associated with improvement in stress MBF, ( r  = -0.616; P  = 0.004).

CONCLUSION

Recovery of myocardial perfusion after PCI was associated with an increase in FFR 3 months after revascularization. Microcirculatory dysfunction was associated with less improvement in myocardial perfusion.

Photon-counting detector CT reduces the rate of referrals to invasive coronary angiography as compared to CT with whole heart coverage energy-integrating detector

BACKGROUND

We sought to compare the degree of maximal stenosis and the rate of invasive coronary angiography (ICA) recommendations in patients who underwent coronary CT angiography (CCTA) with photon-counting detector CT (PCD-CT) versus those who underwent CCTA with whole heart coverage energy-integrating detector CT (EID-CT).

METHODS

In our retrospective single-center study, we included consecutive patients with suspected CAD who underwent CCTA performed with either PCD-CT or a 280-slice EID-CT. The degree of coronary stenosis was classified as no CAD, minimal (1-24 ​%), mild (25-49 ​%), moderate (50-69 ​%), severe stenosis (70-99 ​%), or occlusion.

RESULTS

A total of 812 consecutive patients were included in the analysis, 401 patients scanned with EID-CT and 411 patients with PCD-CT (mean age: 58.4 ​± ​12.4 years, 45.4 ​% female). Despite the higher total coronary artery calcium score (CACS) in the PCD-CT group (10 [interquartile range (IQR) ​= ​0-152.8] vs 1 [IQR ​= ​0-94], p ​< ​0.001), obstructive CAD was more frequently reported in the EID-CT vs PCD-CT group (no CAD: 28.7 ​% vs 26.0 ​%, minimal: 23.2 ​% vs 30.9 ​%, mild: 19.7 ​% vs 23.4 ​%, moderate: 14.5 ​% vs 9.7 ​%, severe: 11.5 ​% vs 8.5 ​% and occlusion: 2.5 ​% vs 1.5 ​%, respectively, p ​= ​0.025). EID-CT was independently associated with downstream ICA (OR ​= ​2.76 [95%CI ​= ​1.58-4.97] p ​< ​0.001) in the overall patient population, in patients with CACS<400 (OR ​= ​2.18 [95%CI ​= ​1.13-4.39] p ​= ​0.024) and in patients with CACS≥400 (OR ​= ​3.83 [95%CI ​= ​1.42-11.05] p ​= ​0.010).

CONCLUSION

In patients who underwent CCTA with PCD-CT the number of subsequent ICAs was lower as compared to patients who were scanned with EID-CT. This difference was greater in patients with extensive coronary calcification.

Assessing Agreement When Agreement Is Hard to Assess-The Agatston Score for Coronary Calcification

Method comparison studies comprised simple scatterplots of paired measurements, a 45-degree line as benchmark, and correlation coefficients up to the advent of Bland-Altman analysis in the 1980s. The Agatston score for coronary calcification is based on computed tomography of the heart, and it originated in 1990. A peculiarity of the Agatston score is the often-observed skewed distribution in screening populations. As the Agatston score has manifested itself in preventive cardiology, it is of interest to investigate how reproducibility of the Agatston score has been established. This review is based on literature findings indexed in MEDLINE/PubMed before 20 November 2021. Out of 503 identified articles, 49 papers were included in this review. Sample sizes were highly variable (10-9761), the main focus comprised intra- and interrater as well as intra- and interscanner variability assessments. Simple analysis tools such as scatterplots and correlation coefficients were successively supplemented by first difference, later Bland-Altman plots; however, only very few publications were capable of deriving Limits of Agreement that fit the observed data visually in a convincing way. Moreover, several attempts have been made in the recent past to improve the analysis and reporting of method comparison studies. These warrant increased attention in the future.

Computed tomography angiography versus Agatston score for diagnosis of coronary artery disease in patients with stable chest pain: individual patient data meta-analysis of the international COME-CCT Consortium

Objectives

There is conflicting evidence about the comparative diagnostic accuracy of the Agatston score versus computed tomography angiography (CTA) in patients with suspected obstructive coronary artery disease (CAD).

Purpose

To determine whether CTA is superior to the Agatston score in the diagnosis of CAD.

Methods

In total 2452 patients with stable chest pain and a clinical indication for invasive coronary angiography (ICA) for suspected CAD were included by the Collaborative Meta-analysis of Cardiac CT (COME-CCT) Consortium. An Agatston score of > 400 was considered positive, and obstructive CAD defined as at least 50% coronary diameter stenosis on ICA was used as the reference standard.

Results

Obstructive CAD was diagnosed in 44.9% of patients (1100/2452). The median Agatston score was 74. Diagnostic accuracy of CTA for the detection of obstructive CAD (81.1%, 95% confidence interval [CI]: 77.5 to 84.1%) was significantly higher than that of the Agatston score (68.8%, 95% CI: 64.2 to 73.1%, p < 0.001). Among patients with an Agatston score of zero, 17% (101/600) had obstructive CAD. Diagnostic accuracy of CTA was not significantly different in patients with low to intermediate (1 to < 100, 100–400) versus moderate to high Agatston scores (401–1000, > 1000).

Conclusions

Results in our international cohort show CTA to have significantly higher diagnostic accuracy than the Agatston score in patients with stable chest pain, suspected CAD, and a clinical indication for ICA. Diagnostic performance of CTA is not affected by a higher Agatston score while an Agatston score of zero does not reliably exclude obstructive CAD.

Key Points

• CTA showed significantly higher diagnostic accuracy (81.1%, 95% confidence interval [CI]: 77.5 to 84.1%) for diagnosis of coronary artery disease when compared to the Agatston score (68.8%, 95% CI: 64.2 to 73.1%, p < 0.001).

• Diagnostic performance of CTA was not affected by increased amount of calcium and was not significantly different in patients with low to intermediate (1 to <100, 100–400) versus moderate to high Agatston scores (401–1000, > 1000).

• Seventeen percent of patients with an Agatston score of zero showed obstructive coronary artery disease by invasive angiography showing absence of coronary artery calcium cannot reliably exclude coronary artery disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-022-08619-4.

Added Value of Computed Tomography Virtual Intravascular Endoscopy in the Evaluation of Coronary Arteries with Stents or Plaques

Coronary computed tomography angiography (CCTA) is a widely used imaging modality for diagnosing coronary artery disease (CAD) but is limited by a high false positive rate when evaluating coronary arteries with stents and heavy calcifications. Virtual intravascular endoscopy (VIE) images generated from CCTA can be used to qualitatively assess the vascular lumen and might be helpful for overcoming this challenge. In this study, one hundred subjects with coronary stents underwent both CCTA and invasive coronary angiography (ICA). A total of 902 vessel segments were analyzed using CCTA and VIE. The vessel segments were first analyzed on CCTA alone. Then, using VIE, the segments were classified qualitatively as either negative or positive for in-stent restenosis (ISR) or CAD. These results were compared, using ICA as the reference, to determine the added diagnostic value of VIE. Of the 902 analyzed vessel segments, CCTA/VIE had sensitivity, specificity, accuracy, positive predictive value, and negative predictive value (shown in %) of 93.9/90.2, 96.2/98.2, 96.0/97.7, 70.0/83.1, and 99.4/99.0, respectively, in diagnosing ISR or CAD, with significantly improved specificity (p = 0.025), accuracy (p = 0.046), and positive predictive value (p = 0.047). VIE can be a helpful addition to CCTA when evaluating coronary arteries.

Calcium scoring: a personalized probability assessment predicts the need for additional or alternative testing to coronary CT angiography

Objective

To assess whether anthropometrics, clinical risk factors, and coronary artery calcium score (CACS) can predict the need of further testing after coronary CT angiography (CTA) due to non-diagnostic image quality and/or the presence of significant stenosis.

Methods

Consecutive patients who underwent coronary CTA due to suspected coronary artery disease (CAD) were included in our retrospective analysis. We used multivariate logistic regression and receiver operating characteristics analysis containing anthropometric factors: body mass index, heart rate, and rhythm irregularity (model 1); and parameters used for pre-test likelihood estimation: age, sex, and type of angina (model 2); and also added total calcium score (model 3) to predict downstream testing.

Results

We analyzed 4120 (45.7% female, 57.9 ± 12.1 years) patients. Model 3 significantly outperformed models 1 and 2 (area under the curve, 0.84 [95% CI 0.83–0.86] vs. 0.56 [95% CI 0.54–0.58] and 0.72 [95% CI 0.70–0.74], p < 0.001). For patients with sinus rhythm of 50 bpm, in case of non-specific angina, CACS above 435, 756, and 944; in atypical angina CACS above 381, 702, and 890; and in typical angina CACS above 316, 636, and 824 correspond to 50%, 80%, and 90% probability of further testing, respectively. However, higher heart rates and arrhythmias significantly decrease these cutoffs (p < 0.001).

Conclusion

CACS significantly increases the ability to identify patients in whom deferral from coronary CTA may be advised as CTA does not lead to a final decision regarding CAD management. Our results provide individualized cutoff values for given probabilities of the need of additional testing, which may facilitate personalized decision-making to perform or defer coronary CTA.

Key Points

• Anthropometric parameters on their own are insufficient predictors of downstream testing. Adding parameters of the Diamond and Forrester pre-test likelihood test significantly increases the power of prediction.

• Total CACS is the most important independent predictor to identify patients in whom coronary CTA may not be recommended as CTA does not lead to a final decision regarding CAD management.

• We determined specific CACS cutoff values based on the probability of downstream testing by angina-, arrhythmia-, and heart rate–based groups of patients to help individualize patient management.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-06921-7) contains supplementary material, which is available to authorized users.

15O-Water Positron Emission Tomography of Myocardial Ischemia in Patients Referred for Percutaneous Coronary Intervention

The diagnostic accuracy of non-invasive diagnostic methods for detecting coronary artery disease has increased in recent years. This study aimed to assess the diagnostic performance of ¹⁵O-water positron emission tomography (PET) in terms of stress myocardial blood flow (MBF) and myocardial flow reserve (MFR) in patients with single-vessel disease referred for percutaneous coronary intervention (PCI), using fractional flow reserve (FFR) value of ≤0.80 as the reference for a significant stenosis. We also assessed the influence of the index of microcirculatory resistance (IMR) on the diagnostic performance of PET. ¹⁵O-water PET FFR and IMR were measured before PCI in 26 patients with single-vessel disease. Stress MBF < 2.5 ml/min/g (95% confidence interval [CI]) had sensitivity 78% (95% CI: 52%-94%), specificity 50% (95% CI: 16%-84%), positive predictive value (PPV) 78% (95% CI: 63%-88%), negative predictive value (NPV) 50% (95% CI: 25%-75%), and accuracy 69% (95% CI: 48%-86%). MFR < 2.5 had sensitivity 72% (95% CI: 47%-90%), specificity 75% (95% CI: 35%-97%), PPV 87% (95% CI: 65%-96%), NPV 55% (95% CI: 34%-74%), and accuracy 73% (95% CI: 52%-88%). In patients with IMR > 24, stress MBF correlated with FFR (r = 0.651; p = 0.016) whereas stress MBF did not correlate with FFR in patients with IMR < 24. In conclusion, stress MBF and MFR had modest diagnostic performance compared to invasive FFR measurements in patients with single-vessel disease.

Soluble Urokinase Plasminogen Activator Receptor is Associated with Coronary Artery Calcification and Cardiovascular Disease in Patients Undergoing Hemodialysis

BACKGROUND/AIMS

Cardiovascular disease (CVD) is an important cause of morbidity and mortality in hemodialysis patients. Vascular calcification is thought to play an important role in causing CVD. Soluble urokinase plasminogen activator receptor (suPAR) is a biomarker strongly predictive of cardiovascular outcomes in the pathogenesis of diabetic patients with renal disease treated with hemodialysis. We investigated the relationship between suPAR and coronary artery calcification (CAC) in patients undergoing maintenance hemodialysis.

METHODS

A total of 99 adult hemodialysis patients were enrolled in this study. Plasma samples were analyzed for suPAR with an enzyme-linked immunosorbent assay and the CAC score was determined with multidetector computed tomography. The occurrence of cardiovascular events and all-cause mortality during follow-up were recorded from January 1, 2010 to June 1, 2016.

RESULTS

In 99 patients treated with maintenance hemodialysis, 91 (91.9%) had varying degrees of CAC, and suPAR correlated positively with the CAC score in a Spearman analysis. In a mean follow-up period of 33 months, 36 patients (36.4%) experienced at least one cardiovascular event. When the quartiles of suPAR concentrations were used as the cutoff points for a subgroup analysis, the incidence of CVD and all-cause mortality was much higher in the higher quartiles of suPAR. In a univariate Cox regression analysis, high suPAR was a risk factor for CVD and all-cause mortality.

CONCLUSION

suPAR is associated with the CAC score and is a risk factor for new-onset CVD in patients undergoing hemodialysis.

Coronary CT Angiography in Heavily Calcified Coronary Arteries: Improvement of Coronary Lumen Visualization and Coronary Stenosis Assessment With Image Postprocessing Methods

To compare the diagnostic value of coronary CT angiography (CCTA) with use of 2 image postprocessing methods (CCTA_S) and (CCTA_OS) and original data (CCTA_O) for the assessment of heavily calcified plaques. Fifty patients (41 men, 9 women; mean age 61.9 years ± 9.1) with suspected coronary artery disease who underwent CCTA and invasive coronary angiography (ICA) examinations were included in the study. Image data were postprocessed with "sharpen" and smooth reconstruction algorithms in comparison with the original data without undergoing any image postprocessing to determine the effects on suppressing blooming artifacts due to heavy calcification in the coronary arteries. Minimal lumen diameter and degree of stenosis were measured and compared between CCTA_S, CCTA_OS, and CCTA_O with ICA as the reference method. The area under the curve (AUC) by receiver-operating characteristic curve analysis (ROC) was also compared among these 3 CCTA techniques. On a per-vessel assessment, the sensitivity, specificity, positive predictive value and negative predictive value, and 95% confidence interval (CI) were 100% (95% CI: 89%, 100%), 33% (95% CI: 22%, 45%), 41% (95% CI: 30%, 53%), 100% (95% CI: 85%, 100%) for CCTA_O, 94% (95% CI: 79%, 99%), 66% (95% CI: 54%, 77%), 57% (95% CI: 43%, 70%), and 95% (95% CI: 85%, 99%) for CCTA_S, 94% (95% CI: 79%, 99%), 44% (95% CI: 32%, 57%), 44% (95% CI: 32%, 57%), and 97% (95% CI: 79%, 99%) for CCTA_OS, respectively. The AUC by ROC curve analysis for CCTA_S showed significant improvement for detection of >50% coronary stenosis in left anterior descending coronary artery compared to that of CCTA_OS and CCTA_O methods (P < 0.05), with no significance differences for detection of coronary stenosis in the left circumflex and right coronary arteries (P > 0.05).CCTA with "sharpen" reconstruction reduces blooming artifacts from heavy calcification, thus, leading to significant improvement of specificity and positive predictive value of CCTA in patients with heavily calcified plaques. However, specificity is still moderate and additional functional imaging may be needed.

Patients With Suspected Coronary Artery Disease Referred for Examinations in the Era of Coronary Computed Tomography Angiography

Invasive coronary angiography (ICA) is the gold standard in the diagnosis of coronary artery disease (CAD), however, associated with rare but severe complications. Patients with a high pretest risk should be referred directly for ICA, whereas a noninvasive strategy is recommended in the remaining patients. In the setting of a university hospital, we investigated the pattern of diagnostic tests used in daily clinical practice. During a 1-year period, consecutive patients with new symptoms suggestive of CAD and referred for exercise stress test, coronary computed tomography angiography (CCTA), single-photon emission computed tomography (SPECT), or ICA qualified for inclusion. The patients were followed for 1 year, and additional downstream diagnostic tests and need of coronary revascularization were registered. A total of 1,069 patients were included. A noninvasive test was the first examination in 797 patients (75%; exercise stress test in 37, CCTA in 450, and SPECT in 310), whereas 272 (25%) were referred directly to ICA. The ICA group had a significant higher pretest probability for CAD, and the percentage of patients with evidence of significant CAD was 31% (84 of 272 patients), whereas 18% (144 of 797 patients) in the noninvasive group (p <0.0001). In the comparison between CCTA and SPECT, there were no significant differences in downstream testing (16% [72 of 444 patients] vs 17% [53 of 310], p = 0.55), and revascularization rate (20% [14 of 69 patients with positive findings] vs 9% [6 of 67], p = 0.09). In conclusion, a noninvasive diagnostic test was chosen as the first test in 3 of 4 patients. Of the patients referred directly for noninvasive examination, 1/5 had significant CAD, whereas 1/3 of those for invasive examination.

Quantitative myocardial perfusion by O-15-water PET: individualized vs. standardized vascular territories

AIMS

Reporting of quantitative myocardial blood flow (MBF) is typically performed in standard coronary territories. However, coronary anatomy and myocardial vascular territories vary among individuals, and a coronary artery may erroneously be deemed stenosed or not if territorial demarcation is incorrect. So far, the diagnostic consequences of calculating individually vs. standardly assessed MBF values have not been reported. We examined whether individual reassignment of vascular territories would improve the diagnostic accuracy of MBF with regard to the detection of significant coronary artery disease (CAD).

METHODS AND RESULTS

Forty-four patients with suspected CAD were included prospectively and underwent coronary CT-angiography and quantitative MBF assessment with O-15-water PET followed by invasive, quantitative coronary angiography, which served as reference. MBF was calculated in the vascular territories during adenosine stress according to a standardized 17-segment American Heart Association model and an individualized model, using CT-angiography to adjust the coronary territories to their feeding vessels. Individually defined territories deviated from standard territories in 52% of patients. However, MBF in the three coronary territories defined by standard and individualized models did not differ significantly, except in one patient, in whom the MBF of an individualized coronary territory deviated sufficiently as to change the test from a false positive to a true negative result in this particular territory.

CONCLUSION

Disparity between standardized and individualized vascular territories was present in half of the patients, but had little clinical impact. Still, caution should be taken not always to rely on standard territories, as this may at times cause misinterpretation.

Coronary computed tomography angiography - tolerability of β-blockers and contrast media, and temporal changes in radiation dose

OBJECTIVE

To determine the risk in administering β-blockers, contrast-induced nephropathy (CIN) and the trend in X-ray use, during coronary computed tomography angiography (CCTA).

METHODS

A total of 416 patients were referred for elective CCTA. To achieve a resting heart rate below 60 beats per minute, oral and/or intravenous β-blockers were administered. Using questionnaires, information on the adverse effects of β-blockers was collected from the patients. The levels of s-creatinine and estimated GFR (eGFR) were measured before and after contrast enhanced CCTA. Radiation exposure was compared with the exposure 3 years earlier.

RESULTS

There was no significant difference in the symptoms (dizziness, lipothymia and palpitations) between patients with and patients without β-blocker pretreatment. Compared to baseline values, the decrease in s-creatinine was not significant (75.2 vs. 74.6 μmol/L, p = 0.09), while the increase in eGFR was not significant (78 vs. 79 mL/min, p = 0.17). Also, subgroups of patients with hypertension, hypercholesterolemia, diabetes or pre-existing slight impairment in renal function did not develop CIN. The mean radiation exposure decreased from 17.5 to 6.7 mSv, p < 0.0001.

CONCLUSIONS

In terms of the side effects of β-blockers and contrast media, there were no short term complications to CCTA. Furthermore, the radiation dose has been dramatically diminished over the last three years.

Optimizing image contrast display improves quantitative stenosis measurement in heavily calcified coronary arterial segments on coronary CT angiography: A proof-of-concept and comparison to quantitative invasive coronary angiography

RATIONALE AND OBJECTIVES

Blooming artifact from calcified plaques often renders measurement of stenosis impossible on coronary computed tomographic angiography (CTA). We sought to evaluate the impact of modifying window level on reducing blooming artifact, and its impact on stenosis quantification.

MATERIALS AND METHODS

We analyzed 125 calcified segments from 53 patients who underwent CTA and invasive coronary angiography (ICA). Segmental stenosis on CTA was measured using three window settings: width of 1000 Hounsfield units (HU) and level of 200 HU ("default"), 1500/200 HU ("widened"), and width and level based on the mean HU of the calcified plaque and pericoronary fat ("calcium-specific"). Segmental stenosis on ICA was quantified by a blinded experienced reader.

RESULTS

ICA found ≥50% stenosis in 30 segments. Displaying segments with widened and calcium-specific settings improved overall accuracy of detecting ≥50% stenosis (P's < 0.001) by increasing the rate of accurately quantifying <50% stenosis (P's < 0.001), and improved correlation of stenosis quantification to ICA (P's < 0.05). There was no difference in stenosis quantification accuracy between widened and calcium-specific window settings. Limits of agreement between CTA stenosis quantification and ICA narrowed with widened and calcium-specific settings.

CONCLUSIONS

We showed for the first time that in calcified segments, widening display window width significantly improved CTA quantification of stenosis compared to ICA.

Coronary CT angiography: Diagnostic value and clinical challenges

Coronary computed tomography (CT) angiography has been increasingly used in the diagnosis of coronary artery disease due to improved spatial and temporal resolution with high diagnostic value being reported when compared to invasive coronary angiography. Diagnostic performance of coronary CT angiography has been significantly improved with the technological developments in multislice CT scanners from the early generation of 4-slice CT to the latest 320- slice CT scanners. Despite the promising diagnostic value, coronary CT angiography is still limited in some areas, such as inferior temporal resolution, motion-related artifacts and high false positive results due to severe calcification. The aim of this review is to present an overview of the technical developments of multislice CT and diagnostic value of coronary CT angiography in coronary artery disease based on different generations of multislice CT scanners. Prognostic value of coronary CT angiography in coronary artery disease is also discussed, while limitations and challenges of coronary CT angiography are highlighted.

Methodological quality of diagnostic accuracy studies on non-invasive coronary CT angiography: influence of QUADAS (Quality Assessment of Diagnostic Accuracy Studies included in systematic reviews) items on sensitivity and specificity

OBJECTIVES

To evaluate the methodological quality of diagnostic accuracy studies on coronary computed tomography (CT) angiography using the QUADAS (Quality Assessment of Diagnostic Accuracy Studies included in systematic reviews) tool.

METHODS

Each QUADAS item was individually defined to adapt it to the special requirements of studies on coronary CT angiography. Two independent investigators analysed 118 studies using 12 QUADAS items. Meta-regression and pooled analyses were performed to identify possible effects of methodological quality items on estimates of diagnostic accuracy.

RESULTS

The overall methodological quality of coronary CT studies was merely moderate. They fulfilled a median of 7.5 out of 12 items. Only 9 of the 118 studies fulfilled more than 75 % of possible QUADAS items. One QUADAS item ("Uninterpretable Results") showed a significant influence (P = 0.02) on estimates of diagnostic accuracy with "no fulfilment" increasing specificity from 86 to 90 %. Furthermore, pooled analysis revealed that each QUADAS item that is not fulfilled has the potential to change estimates of diagnostic accuracy.

CONCLUSIONS

The methodological quality of studies investigating the diagnostic accuracy of non-invasive coronary CT is only moderate and was found to affect the sensitivity and specificity. An improvement is highly desirable because good methodology is crucial for adequately assessing imaging technologies.

KEY POINTS

• Good methodological quality is a basic requirement in diagnostic accuracy studies. • Most coronary CT angiography studies have only been of moderate design quality. • Weak methodological quality will affect the sensitivity and specificity. • No improvement in methodological quality was observed over time. • Authors should consider the QUADAS checklist when undertaking accuracy studies.

Use of 3x2 tables with an intention to diagnose approach to assess clinical performance of diagnostic tests: meta-analytical evaluation of coronary CT angiography studies

OBJECTIVE

To determine whether a 3 × 2 table, using an intention to diagnose approach, is better than the "classic" 2 × 2 table at handling transparent reporting and non-evaluable results, when assessing the accuracy of a diagnostic test.

DESIGN

Based on a systematic search for diagnostic accuracy studies of coronary computed tomography (CT) angiography, full texts of relevant studies were evaluated to determine whether they could calculate an alternative 3 × 2 table. To quantify an overall effect, we pooled diagnostic accuracy values according to a meta-analytical approach.

DATA SOURCES

Medline (via PubMed), Embase (via Ovid), and ISI Web of Science electronic databases.

ELIGIBILITY CRITERIA

Prospective English or German language studies comparing coronary CT with conventional coronary angiography in all patients and providing sufficient data for a patient level analysis.

RESULTS

120 studies (10,287 patients) were eligible. Studies varied greatly in their approaches to handling non-evaluable findings. We found 26 studies (including 2298 patients) that allowed us to calculate both 2 × 2 tables and 3 × 2 tables. Using a bivariate random effects model, we compared the 2 × 2 table with the 3 × 2 table, and found significant differences for pooled sensitivity (98.2 (95% confidence interval 96.7 to 99.1) v 92.7 (88.5 to 95.3)), area under the curve (0.99 (0.98 to 1.00) v 0.93 (0.91 to 0.95)), positive likelihood ratio (9.1 (6.2 to 13.3) v 4.4 (3.3 to 6.0)), and negative likelihood ratio (0.02 (0.01 to 0.04) v 0.09 (0.06 to 0.15); (P<0.05)).

CONCLUSION

Parameters for diagnostic performance significantly decrease if non-evaluable results are included by a 3 × 2 table for analysis (intention to diagnose approach). This approach provides a more realistic picture of the clinical potential of diagnostic tests.

Arterial stiffness contributes to coronary artery disease risk prediction beyond the traditional risk score (RAMA-EGAT score)

Objectives

The traditional risk score (RAMA-EGAT) has been shown to be an accurate scoring system for predicting coronary artery disease (CAD). Arterial stiffness measured by the cardio–ankle vascular index (CAVI) is known to be a marker of atherosclerotic burden. A study was undertaken to determine whether CAVI improves the prediction of CAD beyond the RAMA-EGAT score.

Design

Cross-sectional study.

Patients

Patients with a moderate to high risk for CAD by the RAMA-EGAT score were enrolled between November 2005 and March 2006. 64-slice multidetector CT coronary angiography was used to evaluate the coronary artery calcium score and coronary stenosis. Arterial stiffness was assessed by CAVI.

Results

1391 patients of median age 59 years (range 31–88) were enrolled in the study, 635 (45.7%) men and 756 (54.3%) women. Of the 1391 patients, 346 (24.87%) had coronary stenosis. There was a correlation between CAVI and the prevalence of coronary stenosis after adjusting for traditional CAD risk factors (OR 3.29). In addition, adding CAVI into the RAMA-EGAT score (modified RAMA-EGAT score) improved the prediction of CAD incidence, increasing C-statistics from 0.72 to 0.85 and resulting in a net reclassification improvement of 27.7% (p<0.0001).

Conclusion

CAVI is an independent risk predictor for CAD. The addition of CAVI to the RAMA-EGAT score significantly improves the diagnostic yield of CAD.

The effect of calcium score on the diagnostic accuracy of coronary computed tomography angiography

The influence of coronary calcification on the diagnostic performance of coronary computed tomography angiography (CTA) remains controversial. This study attempts to assess the effect of coronary calcium score (CS) on the diagnostic accuracy of detecting coronary artery disease (CAD) using 64-row multidetector computed tomography (MDCT). Over a period of 2 years and 9 months, 113 symptomatic patients (37-87 year-old, mean 62.3, 92 males) underwent 64-row MDCT for coronary CS and CTA. All had conventional coronary angiography (CCA) within 90 (mean 9.6) days. Coronary CTA was evaluated with CCA as the gold standard. Of 113 patients, 18 patients had a CS of 0, 18 had scores between 1 and 100, 27 between 101 and 400, and 50 had scores >400. With respect to patient-based analysis, the accuracy of CTA was 90.3%, the sensitivity was 95%, and the specificity was 78.8%. Regarding patients with CS > 400, the accuracy, sensitivity, and specificity were 92, 95.6, and 60%, respectively. On vessel-based analysis, the specificity of CTA in different vessels with CS < [double bond] 400 and CS > 400 was as follows: right coronary artery 87.1% versus 87.5% (P = 0.924); left main artery 94.8% versus 66.7% (P = 0.173); left anterior descending artery 77.1% versus 27.3% (P = 0.001); and left circumflex artery 83.3% versus 42.8% (P = 0.011). A high CS does not significantly affect the diagnostic accuracy and sensitivity of CTA; however, it significantly decreases the specificity, particularly the left anterior descending and left circumflex arteries.

Correlation between carotid bifurcation calcium burden on non-enhanced CT and percentage stenosis, as confirmed by digital subtraction angiography

OBJECTIVES

Previous evidence supports a direct relationship between the calcium burden (volume) on post-contrast CT with the percent internal carotid artery (ICA) stenosis at the carotid bifurcation. We sought to further investigate this relationship by comparing non-enhanced CT (NECT) and digital subtraction angiography (DSA).

METHODS

50 patients (aged 41-82 years) were retrospectively identified who had undergone cervical NECT and DSA. A 64-multidetector array CT (MDCT) scanner was utilised and the images reviewed using preset window widths/levels (30/300) optimised to calcium, with the volumes measured via three-dimensional reconstructive software. Stenosis measurements were performed on DSA and luminal diameter stenoses >40% were considered "significant". Volume thresholds of 0.01, 0.03, 0.06, 0.09 and 0.12 cm(3) were utilised and Pearson'S correlation coefficient (r) was calculated to correlate the calcium volume with percent stenosis.

RESULTS

Of 100 carotid bifurcations, 88 were available and of these 7 were significantly stenotic. The NECT calcium volume moderately correlated with percent stenosis on DSA r=0.53 (p<0.01). A moderate-strong correlation was found between the square root of calcium volume on NECT with percent stenosis on DSA (r=0.60, p<0.01). Via a receiver operating characteristic curve, 0.06 cm(3) was determined to be the best threshold (sensitivity 100%, specificity 90.1%, negative predictive value 100% and positive predictive value 46.7%) for detecting significant stenoses.

CONCLUSION

This preliminary investigation confirms a correlation between carotid bifurcation calcium volume and percent ICA stenosis and is promising for the optimal threshold for stenosis detection. Future studies could utilise calcium volumes to create a "score" that could predict high grade stenosis.