Coronary CT angiography (CCTA) and advances in CT plaque imaging

Extracranial carotid artery stenting followed by intracranial stent-based thrombectomy for acute tandem occlusive disease

OBJECTIVE

Acute tandem occlusions of the extracranial internal carotid artery (ICA) and a major intracranial artery respond poorly to intravenous tissue plasminogen activator (tPA) and present an endovascular challenge. We describe our experience with emergency stent-assisted ICA angioplasty and intracranial stent-based thrombectomy of tandem occlusions.

METHODS

Procedures were performed from March 2010 to December 2013. National Institutes of Health Stroke Score (NIHSS) and Alberta Stroke Program Early CT Score (ASPECTS), occlusion sites, collateral supply, procedural details, and outcomes were retrospectively reviewed with IRB waiver of informed consent.

RESULTS

24 patients, mean age 66 years, mean admission NIHSS 20.4, and mean ASPECTS 9 were included. Occlusion sites were proximal ICA-middle cerebral artery (MCA) trunk in 17 patients, proximal ICA-ICA terminus in six, and ICA-MCA-anterior cerebral artery in one. Stent-assisted cervical ICA recanalization was achieved in all patients, with unprotected pre-angioplasty in 24/24, unprotected stenting in 16/24 (67%), and protected stenting in 8/24 (33%), followed by stent-thrombectomy in 25 intracranial occlusions. There was complete recanalization/complete perfusion in 19/24 (79%), complete recanalization/partial perfusion in 3/24 (13%), and partial recanalization/partial perfusion in 2/24 (8%) with no procedural morbidity/mortality. Mean time to therapy was 3.8 h (range 2-5.5) and mean time to recanalization was 51 min (range 38-69). At 3-month follow-up, among 17/22 surviving patients (77%), 13/17 (76%) were modified Rankin Scale (mRS) 0-2 and 3/17 (18%) were mRS 3.

CONCLUSIONS

In acute tandem ICA-MCA/distal ICA occlusions, extracranial stenting followed by intracranial stent-based thrombectomy appears feasible, effective, and safe. Further evaluation of this treatment strategy is warranted.

Computed tomographic coronary angiography - is it ready as a screening tool for coronary artery disease?

Currently, there are no formal screening programmes for coronary artery disease (CAD). Computed tomographic coronary angiography (CTCA) has been suggested as a non-invasive and reliable method of atherosclerotic plaque assessment, with the potential for use in screening programmes. In this article, we briefly present the current understanding of atherosclerotic plaque formation, explain key technological aspects of CTCA and critique this method in the light of World Health Organisation (WHO) criteria for devising a screening programme. Current evolving and future insights are also considered. Overall, in our view, there is currently insufficient evidence to support the formal use of CTCA in a screening programme for CAD, although this viewpoint will undoubtedly evolve.

Combined CT angiography and SPECT myocardial perfusion imaging for the detection of functionally relevant coronary stenoses

The present study aimed to discuss and evaluate the diagnostic performances and incremental clinical values of combined computed tomography coronary angiography (CTCA) and single photon myocardial perfusion imaging (MPI) for the detection of functionally relevant coronary stenoses (FRCS). In total, 54 patients underwent CTCA, MPI and coronary angiography (CAG) within 30 days. The diagnostic performances of CTCA and combined CTCA plus MPI for the detection of significant coronary stenoses (≥50%) were calculated on the patient‑ or vessel‑based levels and included the indices of sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV) and accuracy (AC). On the patient‑based level, the SP, PPV, NPV and AC of CTCA alone or combined with MPI in the detection of FRCS were 90.9 and 90.9, 71.9 and 96.9, 69.0 and 95.2, 92.0 and 93.9 and 79.6 and 94.4%, respectively. On the vessel‑based level, the SN, SP, PPV, NPV and AC of CTCA alone or combined with MPI in the detection of FRCS were 90.3 and 90.3, 87.6 and 98.9, 54.9 and 93.3, 98.2 and 98.4 and 88.0 and 97.7%, respectively. The PPV, SP and AC of combined CTCA and MPI in the detection of FRCS were significantly improved compared with CTCA alone (all values, P<0.05). The diagnostic performance of combined CTCA and MPI in the detection of FRCS not only retains a high SN and NPV, but also markedly improves SP, PPV and AC, which should play an incremental and significant role in the decision‑making process for the revascularization therapy of coronary artery disease (CAD).

Comparative Analysis between SPECT Myocardial Perfusion Imaging and CT Coronary Angiography for Diagnosis of Coronary Artery Disease

The study aims to discuss the relationship and difference between myocardial perfusion imaging (MPI) using SPECT and CT coronary angiography (CTCA) for diagnosis of coronary artery disease (CAD). Five hundred and four cases undergoing MPI and CTCA were comparatively analyzed, including fifty six patients undergoing invasive coronary angiography in the same period. Among patients with negative MPI results, negative or positive CTCA occupied 84.7% or 15.3%, respectively. Among patients with positive MPI, positive or negative CTCA occupied 67.2% or 32.8%, respectively. Among patients with negative CTCA, negative or positive MPI occupied 94.4% or 5.6%, respectively. Among patients with positive CTCA, positive or negative MPI occupied 40.2% or 59.8%, respectively. Negative predictive value was relatively higher than the positive predictive value for positive CTCA eliminating or predicting abnormal haemodynamics. And there was no significant difference for sensitivity, specificity, and accuracy of MPI or CTCA in diagnosing CAD. Both MPI and CTCA have good diagnostic performance for CAD. They provide different and complementary information for diagnosis and evaluation of CAD, namely, detection of ischemia versus detection of atherosclerosis, which are quite different but have a definite internal link for each other.

Multispectral optoacoustic tomography of matrix metalloproteinase activity in vulnerable human carotid plaques

AIMS

Elevated expression of cathepsins, integrins and matrix metalloproteinases (MMPs) is typically associated with atherosclerotic plaque instability. While fluorescent tagging of such molecules has been amply demonstrated, no imaging method was so far shown capable of resolving these inflammation-associated tags with high fidelity and resolution beyond microscopic depths. This study is aimed at demonstrating a new method with high potential for noninvasive clinical cardiovascular diagnostics of vulnerable plaques using high-resolution deep-tissue multispectral optoacoustic tomography (MSOT) technology.

METHODS AND RESULTS

MMP-sensitive activatable fluorescent probe (MMPSense™ 680) was applied to human carotid plaques from symptomatic patients. Atherosclerotic activity was detected by tuning MSOT wavelengths to activation-dependent absorption changes of the molecules, structurally modified in the presence of enzymes. MSOT analysis simultaneously provided morphology along with heterogeneous MMP activity with better than 200 micron resolution throughout the intact plaque tissue. The results corresponded well with epi-fluorescence images made from thin cryosections. Elevated MMP activity was further confirmed by in situ zymography, accompanied by increased macrophage influx.

CONCLUSIONS

We demonstrated, for the first time to our knowledge, the ability of MSOT to provide volumetric images of activatable molecular probe distribution deep within optically diffuse tissues. High-resolution mapping of MMP activity was achieved deep in the vulnerable plaque of intact human carotid specimens. This performance directly relates to pre-clinical screening applications in animal models and to clinical decision potential as it might eventually allow for highly specific visualization and staging of plaque vulnerability thus impacting therapeutic clinical decision making.

Endovascular Treatment of Tandem Extracranial/Intracranial Anterior Circulation Occlusions

Background and Purpose—

Acute ischemic stroke due to tandem occlusions of the extracranial internal carotid artery and intracranial arteries has a poor natural history. We aimed to evaluate our single-center experience with endovascular treatment of this unique stroke population.

Methods—

Consecutive patients with tandem occlusions of the internal carotid artery origin and an intracranial artery (ie, internal carotid artery terminus, M1 middle cerebral artery, or M2 middle cerebral artery) were studied retrospectively. Treatment consisted of proximal revascularization with angioplasty and stenting followed by intracranial intervention. Endpoints were recanalization of both extracranial and intracranial vessels (Thrombolysis In Myocardial Ischemia ≥2), parenchymal hematoma, and good clinical outcome (modified Rankin Scale ≤2) at 3 months.

Results—

We identified 77 patients with tandem occlusions. Recanalization occurred in 58 cases (75.3%) and parenchymal hematoma occurred in 8 cases (10.4%). Distal embolization occurred in 3 cases (3.9%). In 18 of 77 patients (23.4%), distal (ie, intracranial) recanalization was observed after proximal recanalization, obviating the need for distal intervention. Good clinical outcomes were achieved in 32 patients (41.6%). In multivariate analysis, Thrombolysis In Myocardial Ischemia ≥2 recanalization, baseline National Institutes of Health Stroke Scale score, baseline Alberta Stroke Programme Early CT score, and age were significantly associated with good outcome.

Conclusions—

Endovascular therapy of tandem occlusions using extracranial internal carotid artery revascularization as the first step is technically feasible, has a high recanalization rate, and results in an acceptable rate of good clinical outcome. Future randomized, prospective studies should clarify the role of this approach.

CT angiography: current technology and clinical use

Since 1958, catheter angiography has assumed the role of gold standard for vascular imaging, despite the invasive nature of the procedure. Less invasive techniques for vascular imaging, such as computed tomographic angiography (CTA), have been developed and have matured in conjunction with developments in catheter arteriography. In a few cases, such as imaging, the aorta and the pulmonary arteries, CTA has supplanted catheter angiography as the gold standard. The expanding role of CTA emphasizes the need for deep, broad-based understanding of physical principles. This review describes CT hardware and associated software for angiography. The fundamentals of CTA physics are complemented with several clinical examples.