CT angiography in highly calcified arteries: 2D manual vs. modified automated 3D approach to identify coronary stenoses

Traumatic brain injury, coronary atherosclerosis and cardiovascular mortality

BACKGROUND

Traumatic-brain-injury (TBI) is a devastating-condition resulting in cerebral edema and ischemia. This study investigates the association of mild-TBI (mTBI) to sub-clinical atherosclerosis and cardiovascular (CV) mortality.

METHODS

Five hundred and forty-three veterans without known coronary artery disease or diagnosed mental disorder, who underwent coronary artery calcium (CAC) scanning for clinical indications, were followed for a median of 4-years. Veterans' medical diagnoses and neuropsychiatric health status (mTBI vs non-mTBI) were evaluated using VA electronic medical records. CAC was defined as 0, 1-100, 101-400 and 400+.

RESULTS

CAC was higher in mTBI, compared to without-mTBI (p < 0.05). TBI was more prevalent with the-severity of CAC (p < 0.05). Regression-analyses revealed that mTBI is an independent-predictor of CAC (p < 0.01). The CV mortality rate was 25% in mTBI and 10.5% in without-mTBI (p = 0.0001). Multivariable survival regression analyses revealed a significant-association between mTBI and CAC, with increased-risk of CV mortality (p < 0.05). The hazard-ratio of CV mortality was 5.25 in mTBI & CAC > 0, compared to without-mTBI & CAC = 0 (p < 0.05). The risk of CV-mortality was 2.25 for mTBI & CAC = 1-100, 4.93 for mTBI & CAC = 101-400 and 7.06 for mTBI & CAC ≥ 400, compared to matched CAC-categories without-mTBI (p < 0.05). The area under ROC curve to predict CV mortality was 0.64 for mTBI, 0.69 for mTBI & PTSD, 0.85 for mTBI & CAC > 0 and 0.92 for the combination. The prognostication of mTBI to predict CV mortality is superior to the Framingham risk score. Also the combination of mTBI & PTSD provided incremental prognostic values to predict CV mortality (p < 0.05).

CONCLUSIONS

mTBI is associated with the severity of sub-clinical coronary atherosclerosis and independently predicts CV mortality.

Accuracy and predictive value of coronary computed tomography angiography for the detection of obstructive coronary heart disease in patients with an Agatston calcium score above 400

PURPOSE

We assessed the accuracy of coronary computed tomography angiography (CTA) in patients with an Agatston calcium score (ACS) of greater than 400 by comparing it with invasive coronary angiography (ICA), and we evaluated the predictive value of CTA for obstructive coronary heart disease (CHD) compared with traditional clinical risk assessment.

METHODS

A total of 253 patients who had an ACS of greater than 400 were enrolled in this study. The degree of coronary stenosis was visually and quantitatively estimated by postprocessing imaging using 15-segment coronary models. All patients underwent ICA after a mean (SD) of 34 (24) days, and the degree of coronary stenosis was compared with the results of CTA.

RESULTS

Computed tomography angiography accurately diagnosed significant stenosis in 204 (99.0%) of 206 patients and in 649 (83.5%) of 777 segments. When the patients were considered based on their ACS (group A, 400 < ACS ≤ 1000, vs group B, ACS > 1000), group B showed lower specificity (9.1% vs 41.7%) and poorer agreement (k = 0.149 vs 0.495) than for ICA. By segment-based analysis, the agreement between CTA and ICA was good (k = 0.729), and there was no significant difference between groups A (k = 0.728) and B (k = 0.727). Computed tomography angiography was the most powerful predictor (odds ratio = 52.645, P < 0.001), whereas the 10-year CHD risk and pretest probability were not significantly correlated with obstructive CHD.

CONCLUSIONS

Despite good overall diagnostic accuracy, coronary CTA in this group of patients was limited by low specificity. However, CTA was a better predictor of obstructive CHD compared with clinical predictors, and it avoided unnecessary ICA, even in patients with extensive coronary artery calcification.

Coronary CTA: stenosis classification and quantification, including automated measures

The development of larger multidetector computed tomography (CT) systems has allowed increased accuracy in quantifying obstructive lesions involving the coronary arteries. This article reviews the accuracy of coronary CT angiography (CTA) in quantifying obstructive lesions, evaluating the extent of coronary artery disease, and classifying the composition of coronary plaques. In addition, several outcomes studies and some promising automated techniques for quantifying coronary CTA are reviewed.

Intraindividual comparison of 3D coronary MR angiography and coronary CT angiography

RATIONALE AND OBJECTIVES

To compare the diagnostic value of magnetic resonance (MR) and computed tomography (CT) for the detection of coronary artery disease (CAD) with special regard to calcifications.

MATERIALS AND METHODS

Twenty-seven patients with known CAD were examined with a targeted, navigator-gated, free-breathing, steady-state free precession MR angiography sequence (repetition time = 5.6 milliseconds, echo time = 2.8 milliseconds, flip angle 110 degrees ) and 16-slice coronary CT angiography. Segment-based sensitivity, specificity, and accuracy for the detection of stenoses larger than 50% were determined as defined by the gold standard catheter coronary angiography along with the subjective image quality (Grade 1-4). The degree of calcifications in each segment was quantified using a standard calcium scoring tool.

RESULTS

Of 115 possible segments, 7% had to be excluded in MR imaging because of poor image quality. In CT, 3% were nondiagnostic because of image quality and 15% were not evaluable because of calcifications. Values for the detection of relevant coronary artery stenoses in the evaluated segments were: sensitivity: MR imaging 85% versus CT 96%; specificity: 88% versus 96%; accuracy: 87% versus. 96%. Average subjective image quality was 1.8 for MR imaging and 1.6 for CT. Of the 15% of segments that had to be excluded from CT evaluation because of calcifications, MR imaging provided the correct diagnosis segments in 67%.

CONCLUSIONS

CT provided a better image quality with superior accuracy for the detection of CAD. Despite its overall inferiority, MR imaging proved to be helpful method in interpreting coronary stenosis in severely calcified segments.

Accuracy and rate of coronary artery segment visualization with CT angiography for the non-invasive detection of coronary artery stenoses

OBJECTIVES

To evaluate CT coronary angiography (CTA) when compared with catheter coronary angiography (CCA), for the detection of coronary artery stenoses and rate of optimal coronary artery segment visualization.

METHOD

Retrospective, two-center study enrolling 26 patients who underwent CCA and ECG-gated 16-detector CTA (slice thickness 0.6 mm; rotation 500 ms).

RESULTS AND CONCLUSION

283 segments were available for postprocessing. Sensitivity, specificity, and positive predictive value were, respectively, 80, 100, and 100%, for detecting more than 50% luminal stenoses, when optimally visualized segments were considered, in comparison to CCA. Negative predictive value was excellent (98%). Rate of non-optimally visualized coronary segments was 26%. Most clinical benefits of coronary CT angiography should probably be obtained when it is performed to exclude significant stenoses on selected populations of patients with a low pre-test probability of severe coronary artery disease, and under optimal conditions of controlled heart rate and minimal presence of calcium.

Atherosclerotic Plaque Characterization by Multidetector Row Computed Tomography Angiography

Multidetector row computed tomography angiography (MDCTA) is seen as a potential alternative to current imaging methods for the assessment of vessel anatomy and atherosclerotic plaque composition/morphology in a great variety of arterial beds. Recent advances represented by the increase in gantry speed to <500 ms per rotation and in the number of detector rows from 4 to 64, in addition to the decrease in slice thickness to submillimetric levels, brought significant improvement in diagnostic accuracy by coronary MDCTA. In general, it has a good correlation with both intravascular ultrasound (IVUS) and histopathology for discrimination between soft, intermediate, and calcified plaques. Plaque area and volume tend to be underestimated by 12-detector row MDCTA and overestimated by 16-detector row MDCTA, but the number of patients studied so far is relatively small. However, it seems that 64-detector row MDCTA can measure plaque area and volume with greater accuracy. Plaque remodeling is overestimated in small vessels by 12-detector row MDCTA, whereas 16- and 64-detector row MDCTA show a good correlation with IVUS. Although still under development, the potential of MDCTA to characterize atherosclerotic plaque composition as well as to precisely determine plaque area, volume, and remodeling in the future is quite promising.

Non-invasive half millimetre 32 detector row computed tomography angiography accurately excludes significant stenoses in patients with advanced coronary artery disease and high calcium scores

OBJECTIVE

To show an overall diagnostic accuracy > or = 90% for detection of > or = 50% stenoses by coronary half millimetre 32 detector row computed tomography angiography (32 x 0.5-MDCTA) in patients with advanced coronary artery disease (CAD) and a high likelihood of raised calcium scores.

METHODS

ECG gated 32 x 0.5-MDCTA (32 x 0.5 mm cross sections, 0.35 x 0.35 x 0.35 mm3 isotropic voxels, 400 ms rotation) was performed after injection of iodixanol (120 ml, 320 mg/ml) in 30 consecutive patients (25 men, mean (SD) age 59 (13) years, body mass index 26.2 (4.9) kg/m2). Native arteries, including > or = 1.5 mm branches, and bypass grafts were screened for > or = 50% stenoses. Stents were excluded. Conventional coronary angiography (performed 18 (12) days before 32 x 0.5-MDCTA) was analysed by quantitative coronary angiography.

RESULTS

Median Agatston calcium score was 510 (range 3-5066). Sensitivity, specificity, and positive and negative predictive values for detection of > or = 50% stenoses in native arteries were 76% (29 of 38), 94% (190 of 202), 71% (29 of 41), and 96% (190 of 199), respectively. Overall diagnostic accuracy was 91% (219 of 240). Due to the following artefacts 20% (69 of 352) of the vessels were excluded: motion, noise, and low contrast enhancement isolated or in combination (45 of 69 (65%)); image distortion by implantable cardioverter-defibrillator or pacemaker leads (18 of 69 (26%)); and blooming secondary to severe calcification (6 of 69 (9%)).

CONCLUSIONS

Coronary 32 x 0.5-MDCTA accurately excludes > or = 50% stenoses in patients with advanced CAD and high calcium scores with an overall diagnostic accuracy of 91%.