First In-Human Results of Computed Tomography Angiography for Coronary Stent Assessment With a Spectral Photon Counting Computed Tomography.

OBJECTIVES: The aim of this study is to compare the image quality of in vivo coronary stents between an energy integrating detectors dual-layer computed tomography (EID-DLCT) and a clinical prototype of spectral photon counting computed tomography (SPCCT). MATERIALS AND METHODS: In January to June 2021, consecutive patients with coronary stents were prospectively enrolled to undergo a coronary computed tomography (CT) with an EID-DLCT (IQon, Philips) and an SPCCT (Philips). The study was approved by the local ethical committee and patients signed an informed consent. A retrospectively electrocardiogram-gated acquisition was performed with optimized matching parameters on the 2 scanners (EID-DLCT: collimation, 64 × 0.625 mm; kVp, 120, automatic exposure control with target current at 255 mAs; rotation time, 0.27 seconds; SPCCT: collimation, 64 × 0.275 mm; kVp, 120; mAs, 255; rotation time, 0.33 seconds). The injection protocol was the same on both scanners: 65 to 75 mL of Iomeron (Bracco) at 5 mL/s. Images were reconstructed with slice thickness of 0.67 mm, 512 matrix, XCB (Xres cardiac standard) and XCD (Xres cardiac detailed) kernel, iDose 3 for EID-DLCT and 0.25-mm slice thickness, 1024 matrix, Detailed 2 and Sharp kernel, and iDose 6 for SPCCT. Two experienced observers measured the proximal and distal external and internal diameters of the stents to quantify blooming artifacts. Regions of interest were drawn in the lumen of the stent and of the upstream coronary artery. The difference (Δ S-C) between the respective attenuation values was calculated as a quantification of stent-induced artifacts on intrastent image quality. For subjective image quality, 3 experienced observers graded with a 4-point scale the image quality of different parameters: coronary wall before the stent, stent lumen, stent structure, calcifications surrounding the stent, and beam-hardening artifacts. RESULTS: Eight patients (age, 68 years [interquartile range, 8]; all men; body mass index, 26.2 kg/m2 [interquartile range, 4.2]) with 16 stents were scanned. Five stents were not evaluable owing to motion artifacts on the SPCCT. Of the remaining, all were drug eluting stents, of which 6 were platinum-chromium, 3 were cobalt-platinum-iridium, and 1 was stainless steel. For 1 stent, no information could be retrieved. Radiation dose was lower with the SPCCT (fixed CT dose index of 25.7 mGy for SPCCT vs median CT dose index of 35.7 [IQ = 13.6] mGy; P = 0.02). For 1 stent, the internal diameter was not assessable on EID-DLCT. External diameters were smaller and internal diameters were larger with SPCCT (all P < 0.05). Consequently, blooming artifacts were reduced on SPCCT (P < 0.05). Whereas Hounsfield unit values within the coronary arteries on the 2 scanners were similar, the Δ S-C was lower for SPCCT-Sharp as compared with EID-DLCT-XCD and SPCCT-Detailed 2 (P < 0.05). The SPCCT received higher subjective scores than EID-DLCT for stent lumen, stent structure, surrounding calcifications and beam-hardening for both Detailed 2 and Sharp (all P ≤ 0.05). The SPCCT-Sharp was judged better for stent structure and beam-hardening assessment as compared with SPCCT-Detailed 2. CONCLUSION: Spectral photon counting CT demonstrated improved objective and subjective image quality as compared with EID-DLCT for the evaluation of coronary stents even with a reduced radiation dose.

Impact of Arterial Blood Pressure on Ultrasound Hemodynamic Assessment of Aortic Valve Stenosis Severity.

BACKGROUND: Aortic stenosis (AS) severity assessment is based on several indices. Aortic valve area (AVA) is subject to inaccuracies inherent to the measurement method, while velocities and gradients depend on hemodynamic status. There is controversy as to whether blood pressure directly affects common indices of AS severity. OBJECTIVES: The study objective was to assess the effect of systolic blood pressure (SBP) variation on AS indices, in a clinical setting. METHODS: A prospective, single-center study included 100 patients with at least moderately severe AS with preserved left ventricle ejection fraction. Patients underwent ultrasound examination during which AS severity indices were collected, with three hemodynamic conditions: (1) low SBP: <120 mm Hg; (2) intermediate SBP: between 120 and 150 mm Hg; (3) high SBP: ≥150 mm Hg. For each patient, SBP profiles were obtained by injection of isosorbide dinitrate or phenylephrine. RESULTS: At baseline state, 59% presented a mean gradient (Gmean) ≥ 40 mm Hg, 44% a peak aortic jet velocity (Vpeak) ≥4 m/sec, 66% a dimensionless index (DI) ≤0.25, and 87% an indexed AVA (AVAi) ≤ 0.6 cm2/m2. Compared with intermediate and low SBP, high SBP induced a significant decrease in Gmean (39 ± 12 vs 43 ± 12 and 47 ± 12 mm Hg, respectively; P < .05) and in Vpeak (3.8 ± 0.6 vs 4.0 ± 0.6 and 4.2 ± 0.6 mm Hg; P < .05). Compared with the baseline measures, in 16% of patients with an initial Gmean< 40 mm Hg, gradient rose above 40 mm Hg after optimization of the afterload (low SBP; P < .05). Conversely, DI and AVAi did not vary with changes in hemodynamic conditions. Flow rate, not stroke volume was found to impact Gmean and Vpeak but not AVA and DI (P < .05). CONCLUSIONS: Hemodynamic conditions may affect the AS ultrasound assessment. High SBP, or afterload, leads to an underestimation of AS severity when based on gradients and velocities. Systolic blood pressure monitoring and control are crucial during AS ultrasound assessment.

Assessment of Inter-Expert Variability and of an Automated Segmentation Method of 40 and 60 MHz IVUS Images of Coronary Arteries.

The objectives were to compare the performance of a segmentation algorithm, based on the minimization of an uncertainty function, to delineate contours of external elastic membrane and lumen of human coronary arteries imaged with 40 and 60 MHz IVUS, and to use values of this function to delineate portions of contours with highest uncertainty. For 8 patients, 40 and 60 MHz IVUS coronary data acquired pre- and post-interventions were used, for a total of 68,516 images. Manual segmentations of contours (on 2312 images) performed by experts at three core laboratories were the gold-standards. Inter-expert variability was highest on contour points with largest values of the uncertainty function (p < 0.001). Inter-expert variability was lower at 60 than 40 MHz for external elastic membrane (p = 0.013) and lumen (p = 0.024). Average differences in plaque (and atheroma) burden between algorithmic contours and experts' contours were within inter-expert variability (p < 0.001).

close: Closure of patent foramen ovale, oral anticoagulants or antiplatelet therapy to prevent stroke recurrence: Study design.

RATIONALE: Currently available data do not provide definitive evidence on the comparative benefits of closure of patent foramen ovale, oral anticoagulants and antiplatelet therapy in patients with patent foramen ovale-associated cryptogenic stroke AIM: To assess whether transcatheter patent foramen ovale closure plus antiplatelet therapy is superior to antiplatelet therapy alone and whether oral anticoagulant therapy is superior to antiplatelet therapy, for secondary stroke prevention in patients aged 16 to 60 years with a large patent foramen ovale or a patent foramen ovale associated with an atrial septal aneurysm, and an otherwise unexplained ischaemic stroke or retinal ischaemia. SAMPLE SIZE: Six hundred and sixty-four patients were included in the study. METHODS AND DESIGN: CLOSE is an academic-driven, multicentre, randomized, open-label, three-group, superiority trial with blinded adjudication of outcome events. The trial has been registered with Clinical Trials Register (Clinicaltrials.gov, NCT00562289). Patient recruitment started in December 2007. Patient follow-up will continue until December 2016. Expected mean follow-up = 5.6 years. STUDY OUTCOMES: The primary efficacy outcome is the occurrence of fatal or nonfatal stroke. Safety outcomes include fatal, life-threatening or major procedure- or device-related complications and fatal, life-threatening or major haemorrhagic complications. DISCUSSION: CLOSE is the first specifically designed trial to assess the superiority of patent foramen ovale closure over antiplatelet therapy alone and the superiority of oral anticoagulants over antiplatelet therapy to prevent stroke recurrence in patients with patent foramen ovale-associated cryptogenic stroke.

150 microgram intracoronary adenosine bolus for accurate fractional flow reserve assessment of angiographically intermediate coronary stenosis.

AIMS: Fractional flow reserve measurement is based upon achieving maximum hyperemia. A 40 microg intracoronary (IC) adenosine bolus sometimes seems insufficient, and we therefore sought to assess the possible role of 100-150 microg boli in routine. METHODS AND RESULTS: 108 intermediate (49+/-16%) stenoses were consecutively studied with 6F catheters. A history of myocardial infarction in the territory of the explored artery or myocardial hypertrophy were the exclusion criteria. Mean FFR was 0.82+/-0.12 with a 40 microg adenosine bolus and decreased to 0.80+/-0.12 and 0.80+/-13 respectively with 100microg and 150 microg boli (P<0.001 vs 40microg in both cases; 100 vs 150 microg, NS). The 40 microg bolus failed to diagnose 8 out of 30 (27%) significant stenoses (i.e., final FFR <0.75). The large boli led to 12 (11%) transient asymptomatic and spontaneously resolving AV blocks without other side-effects. CONCLUSION: FFR underestimated a quarter of intermediate stenoses with the currently used 40microg IC adenosine bolus. A large bolus up to 150 microg appears to be accurate and safe for routine FFR measurement.

Noninvasive assessment of left main coronary stent patency with 16-slice computed tomography.

We investigated the ability of 16-slice computer tomography (CT) to discriminate any restenosis after left main coronary artery stenting in 29 consecutive patients. CT was able to detect all stents and analyze the lumen properly in 27 of 29 cases. With the exception of arrhythmic or heavily calcified segments, multislice CT provides a noninvasive alternative to conventional coronary angiography in the follow-up of left main angioplasty with stenting.