Accuracy of 64-slice CT angiography for the detection of functionally relevant coronary stenoses as assessed with myocardial perfusion SPECT

Purpose: CT angiography (CTA) offers a valuable alternative for the diagnosis of CAD but its value in the detection of functionally relevant coronary stenoses remains uncertain. We prospectively compared the accuracy of 64-slice CTA with that of myocardial perfusion imaging (MPI) using 99mTc-tetrofosmin-SPECT as the gold standard for the detection of functionally relevant coronary artery disease (CAD). Methods: MPI and 64-slice CT were performed in 100 consecutive patients. CTA lesions were analysed quantitatively and area stenoses ≥50% and ≥75% were compared with the MPI findings. Results: In 23 patients, MPI perfusion defects were found (12 reversible, 13 fixed). A total of 399 coronary arteries and 1,386 segments was analysed. Eighty-four segments (6.1%) in 23 coronary arteries (5.8%) of nine patients (9.0%) were excluded owing to insufficient image quality. In the remaining 1,302 segments, quantitative CTA revealed stenoses ≥50% in 57 of 376 coronary arteries (15.2%) and stenoses ≥75% in 32 (8.5%) coronary arteries. Using a cut-off at ≥75% area stenosis, CTA yielded the following sensitivity, specificity, negative (NPV) and positive predictive value (PPV), and accuracy for the detection of any (fixed and reversible) MPI defect: by patient, 75%, 90%, 93%, 68% and 87%, respectively; by artery, 76%, 95%, 99%, 50% and 94%, respectively. Conclusion: Sixty-four-slice CTA is a reliable tool to rule out functionally relevant CAD in a non-selected population with an intermediate pretest likelihood of disease. However, an abnormal CTA is a poor predictor of ischaemi

Coronary CT angiography in calcified coronary plaques: Comparison of diagnostic accuracy between bifurcation angle measurement and coronary lumen assessment for diagnosing significant coronary stenosis.

BACKGROUND: To investigate the diagnostic value of coronary CT angiography (CCTA) by bifurcation angle measurement in the assessment of calcified plaques compared to conventional coronary lumen analysis. METHODS: Fifty-three patients with calcified plaques identified on CCTA in the left coronary artery were included in the study. Minimal lumen diameter (MLD) and bifurcation angle between the left anterior descending (LAD) and left circumflex (LCx) arteries were measured and compared between CCTA and invasive coronary angiography (ICA), while the areas under the curves (AUCs) by receiver-operating characteristic curve analysis (ROC) were compared between CCTA and ICA with regard to the diagnostic value of using bifurcation angle as a criterion. RESULTS: On a per-vessel assessment, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) and 95% confidence interval (CI) with the use of bifurcation angle for determining coronary stenosis were 100% (86%, 100%), 79% (59%, 92%), 81% (62%, 92%), and 100% (85%, 100%) for CCTA, and 100% (86%, 100%), 82% (63%, 94%), 83% (65%, 94%), and 100% (85%, 100%) for ICA, respectively. While the sensitivity and NPV remained unchanged, the specificity and PPV of CCTA by MLD were 33% (21%, 47%) and 43% (31%, 56%). The AUCs by ROC curve analysis for CCTA and ICA bifurcation angle measurements demonstrated no significant difference (p>0.05, 0.79 vs 0.86, and 0.70 vs 0.68 at the LAD and LCx assessment, respectively). CONCLUSION: Coronary CT angiography by bifurcation angle measurement shows significant improvement in the diagnosis of calcified plaques with diagnostic value comparable to invasive coronary angiography

Hybrid Imaging for the Detection of Obstructive Coronary Artery Disease

ABSTRACT Coronary artery disease (CAD) is globally one of the leading causes of morbidity and mortality. CAD develops over decades when coronary arteries obstruct, typically causing chest pain symptoms and, in the worst case, death. Nowadays, obstructive CAD can be prevented and treated with modern and potent therapies; hence, accurate diagnostic tools have become more important. The aim of this thesis was to evaluate hybrid imaging techniques, i.e., combinations of two imaging techniques, for use in the detection of obstructive CAD. We evaluated the feasibility and accuracy of combined coronary computed tomography angiography (CTA) and either positron emission tomography (PET) myocardial perfusion imaging or coronary Doppler ultrasound to detect obstructive CAD in 107 symptomatic patents with an intermediate (30–70%) pretest probability of disease. Techniques were compared with invasive coronary angiography combined with physiological evaluation by fractional flow reserve. Our results showed that hybrid PET-CTA was highly accurate for detecting obstructive CAD and more accurate than either technique alone. Furthermore, measurement of myocardial blood flow by PET during vasodilator stress only was sufficient to evaluate the hemodynamic significance of coronary stenosis. We found that assessment of the coronary flow velocity profile at rest by Doppler ultrasound provides information on the hemodynamic significance of coronary stenosis identified by coronary CTA and may aid in detecting obstructive CAD. These results show the feasibility of hybrid imaging and demonstrate that it provides improved accuracy in detecting obstructive CAD as compared with standalone coronary CTA.TIIVISTELMÄ Sepelvaltimotauti on yksi yleisimmista kuolemaan johtavista sairauksista maailmassa. Tauti kehittyy vuosikymmenten aikana, jolloin sepelvaltimot ahtautuvat aiheuttaen taudille tyypilliset oireet. Nykyisilla, tehokkailla hoitomuodoilla tautia voidaan ennaltaehkaista ja hoitaa, minka vuoksi sairauden tasmallinen diagnostiikka on muodostunut entista tarkeammaksi. Taman vaitoskirjan tavoite oli tutkia hybridikuvantamisen, eli kahden eri kuvantamistutkimuksen yhdistelman diagnostista osuvuutta ahtauttavan sepelvaltimotaudin toteamisessa oireisilla potilailla, joilla taudin todennakoisyys oli keskisuuri. Tutkimme sepelvaltimoiden tietokonetomografian (TT) ja joko positroniemissiotomografia (PET) -menetelmalla mitatun sydanlihaksen verenvirtauksen tai ultraaanella mitatun sepelvaltimovirtausprofiilin yhdistelmaa 107 potilaan aineistossa. Kuvantamismenetelmia verrattiin perinteiseen katetriangiografiaan, jota taydennettiin tarvittaessa sepelvaltimon sisaisella painemittauksella. Tulokset osoittavat, etta sepelvaltimoiden TT:n ja PET-kuvauksen yhdistelma on tarkka menetelma ahtauttavan sepelvaltimotaudin toteamisessa ja yhdistelma on tarkempi kuin kumpikaan menetelma yksin. Sydanlihaksen verenvirtauksen mittaaminen PET kameralla pelkan adenosiinirasituksen aikana ilman levossa tehtavaa mittausta riittaa ahtauttavan sepelvaltimotaudin toteamiseen. Lisaksi havaitsimme, etta sepelvaltimon virtausprofiilin mittaaminen levossa Dopplerultraaanella auttaa sepelvaltimoiden TT -kuvauksessa todetun ahtauman vaikeusasteen arvioinnissa ja voi auttaa taudin diagnostiikassa. Hybridikuvantaminen parantaa ahtauttavan sepelvaltimotaudin diagnostiikkaa verrattuna pelkkaan sepelvaltimoiden TT-kuvaukseen. Hybridikuvantaminen on toteutettavissa kliinisessa diagnostiikassa

Cardiovascular Magnetic Resonance Myocardial Perfusion Mapping for the Assessment of Coronary Artery Disease

Pixelwise myocardial perfusion mapping is a novel cardiovascular magnetic resonance (CMR) technique enables quantitative measurement of myocardial blood flow (MBF) at a pixel level. This could improve the accuracy of detection of obstructive coronary artery disease (CAD) and may also have a role in the diagnosis and assessment of coronary microvascular dysfunction (CMD). In this thesis, I explore the use of this novel technique in cohorts of clinical patients and controls with suspected CAD or CMD. Firstly, I demonstrate that stress MBF measured using perfusion mapping is accurate for the detection of CAD using invasive fractional flow reserve (FFR) as the reference standard, and that global stress MBF can be used as a marker of CMD using invasive index of microcirculatory resistance (IMR) as the reference standard. One limitation of adenosine stress testing is the confirmation of adequate hyperaemia with lack of gold standard non-invasive marker. Here, I demonstrate that regional stress MBF can be utilised as a non-invasive marker of adequate stress response. Another limitation of stress MBF is the relatively poor performance for the detection of multivessel disease. In a cohort of patients with confirmed two- and three-vessel disease I demonstrate that perfusion mapping is superior to visual analysis for the correct identification of disease severity. Perfusion mapping provides a host of options for quantitative image analysis. I show that the most reliable method for detection of coronary disease at a patient level is the presence of reduced MBF in two adjacent myocardial segments. In summary, in this thesis I performed a series of studies investigating the clinical utilisation of CMR perfusion mapping that can be translated to clinical practice to enhance the performance of stress perfusion CMR

Insight from imaging on plaque vulnerability: similarities and differences between coronary and carotid arteries—implications for systemic therapies

Nowadays it is widely accepted that the rupture of the atherosclerotic plaque in coronary and carotid arteries plays a fundamental role in the development of acute myocardial infarctions or cerebrovascular events. In recent years, imaging techniques have explored, with a new level of detail, the atherosclerotic disease generating new evidences that some plaque characteristics are significantly associated to the risk of rupture and subsequent thrombosis or embolization. Moreover, the recent evidence of the anti-atherosclerotic effects determined by lipid-lowering and anti-inflammatory therapies poses a challenge for the choice of therapeutic approaches (best/optimal medical therapy vs. revascularization), maximized by the evidence that coronary and carotid atherosclerosis share common patterns but also differ regarding some important features. In this Review, we discuss the similarities and differences between coronary and carotid artery vulnerable plaque from the imaging point of view and the potential implications for systemic therapies according to the emerging evidence

Coronary Angiography

In the intervening 10 years tremendous advances in the field of cardiac computed tomography have occurred. We now can legitimately claim that computed tomography angiography (CTA) of the coronary arteries is available. In the evaluation of patients with suspected coronary artery disease (CAD), many guidelines today consider CTA an alternative to stress testing. The use of CTA in primary prevention patients is more controversial in considering diagnostic test interpretation in populations with a low prevalence to disease. However the nuclear technique most frequently used by cardiologists is myocardial perfusion imaging (MPI). The combination of a nuclear camera with CTA allows for the attainment of coronary anatomic, cardiac function and MPI from one piece of equipment. PET/SPECT cameras can now assess perfusion, function, and metabolism. Assessing cardiac viability is now fairly routine with these enhancements to cardiac imaging. This issue is full of important information that every cardiologist needs to now

Non-invasive detection and assessment of coronary stenosis from blood mean residence times.

Coronary artery stenosis is an abnormal narrowing of a coronary artery caused by an atherosclerotic lesion that reduces lumen space. Fractional flow reserve (FFR) is the gold standard method to determine the severity of coronary stenosis based on the determination of rest and hyperemic pressure fields, but requires an invasive medical procedure. Normal FFR is 1.0 and FFR RT, to account for varying volume and flow rate of individual segments. BloodRT was computed in 100 patients who had undergone the pressure-wire FFR procedure, and a threshold for BloodRT was determined to assess the physiological significance of a stenosis, analogous to the diagnostic threshold for FFR. The threshold exhibited excellent discrimination in detecting significant from non-significant stenosis compared to the gold standard pressure-wire FFR, with sensitivity of 98% and specificity of 96%. When applied to clinical practice, this could potentially allow practicing cardiologists to accurately assess and quantify the severity of coronary stenosis without resorting to invasive catheter-based techniques. The first 100 patient study required a clinically determined blood flow rate as a key model input. To create a more non-invasive process, a multiple linear regression approach was employed to determine blood flow rate entering a given artery segment. To validate this method, BloodRT was computed for a new set of 100 patients using the regression derived blood flow rate. The sensitivity and specificity were 95% and 97%, respectively, indicating similar discrimination compared to the clinically derived flow rate. The method was also applied to a succession of stenosis in series. When BloodRT of each individual stenosis was well above the threshold for significance, the cumulative effect of all stenoses led to an overall BloodRT below the threshold of hemodynamic significance