Correlation between quantitative angiographic and intravascular ultrasound parameters in patients treated with sirolimus analogous-eluting stents

Despite the undeniable contribution of intravascular ultrasound (IVUS) and quantitative coronary angiography (QCA) to assess drug-eluting stent (DES) effectiveness, the way these image modalities correlate to each other and to target-lesion revascularization (TLR) after PCI, is yet to be established. Thus we sought to evaluate whether there is an acceptable correlation between QCA and IVUS after DES implantation. We analyzed 204 pts treated with DES: Zotarolimus- (126), Sirolimus- (57), and Biolimus (31) with baseline and follow-up QCA and IVUS. The correlation between QCA lumen loss (LL) and intimal hyperplasia (IH) volume obstruction by IVUS was assessed by multiple regression analysis. Two QCA parameters (in-segment diameter stenosis and in-segment LL) and one IVUS variable (in-stent volume of IH) were evaluated as quantitative surrogates of 6 month TLR. The receiver operating characteristic method with c-statistics was used to assess the ability of each surrogate endpoint to predict TLR. QCA LL correlated positively with IVUS IH volume of obstruction (r = 0.69; CI95% 0.61–0.75: P < 0.0001), independent of DES type. The 2 QCA parameters were superior to the IVUS parameter as surrogates for TLR. Of note, QCA LL (c = 0.99) correlated best with TLR, even better than percent DS. In the DES era there is a good correlation between QCA measured LL and IVUS IH volume and therefore can be used as a surrogate of DES efficacy.     

Evaluation of in-stent restenosis in the APPROACH trial (assessment on the prevention of progression by Rosiglitazone on atherosclerosis in diabetes patients with cardiovascular history)

To determine (1) the medium-term effect of rosiglitazone and glipizide on intra-stent neointima hyperplasia, (2) restenosis pattern as assessed by intra-vascular ultrasound (IVUS) and quantitative coronary angiography (QCA) in patients with T2DM and coronary artery disease. A total of 462 patients with T2DM were randomized to rosiglitazone or glipizide for up to 18?months in the APPROACH trial, and had evaluable baseline and follow-up IVUS examinations. There was no significant difference in the size of plaque behind stent between the rosiglitazone and glipizide groups at 18?months among those treated with a bare metal stent (?5.6 mm³ vs. 1.9?mm³; P?=?0.61) or with a drug-eluting stent (12.1 mm³ vs. 5.5?mm³; P?=?0.09). Similarly, there was no significant difference in percentage intimal hyperplasia volume between the rosiglitazone and glipizide groups at 18?months among those treated with a bare metal stent (24.1% vs. 19.8%; P?=?0.38) or with a drug-eluting stent (9.8% vs. 8.3%; P?=?0.57). QCA data (intra-stent late loss, intra-stent diameter stenosis or binary restenosis) were not different between the rosiglitazone and glipizide groups. This study suggests that both rosiglitazone and glipizide have a similar effect on neointimal growth at medium term follow-up, a finding that warrants investigation in dedicated randomized trials.     

Fusion of 3D QCA and IVUS/OCT

The combination/fusion of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS)/optical coherence tomography (OCT) depends to a great extend on the co-registration of X-ray angiography (XA) and IVUS/OCT. In this work a new and robust three-dimensional (3D) segmentation and registration approach is presented and validated. The approach starts with standard QCA of the vessel of interest in the two angiographic views (either biplane or two monoplane views). Next, the vessel of interest is reconstructed in 3D and registered with the corresponding IVUS/OCT pullback series by a distance mapping algorithm. The accuracy of the registration was retrospectively evaluated on 12 silicone phantoms with coronary stents implanted, and on 24 patients who underwent both coronary angiography and IVUS examinations of the left anterior descending artery. Stent borders or sidebranches were used as markers for the validation. While the most proximal marker was set as the baseline position for the distance mapping algorithm, the subsequent markers were used to evaluate the registration error. The correlation between the registration error and the distance from the evaluated marker to the baseline position was analyzed. The XA-IVUS registration error for the 12 phantoms was 0.03 ± 0.32 mm (P = 0.75). One OCT pullback series was excluded from the phantom study, since it did not cover the distal stent border. The XA-OCT registration error for the remaining 11 phantoms was 0.05 ± 0.25 mm (P = 0.49). For the in vivo validation, two patients were excluded due to insufficient image quality for the analysis. In total 78 sidebranches were identified from the remaining 22 patients and the registration error was evaluated on 56 markers. The registration error was 0.03 ± 0.45 mm (P = 0.67). The error was not correlated to the distance between the evaluated marker and the baseline position (P = 0.73). In conclusion, the new XA-IVUS/OCT co-registration approach is a straightforward and reliable solution to combine X-ray angiography and IVUS/OCT imaging for the assessment of the extent of coronary artery disease. It provides the interventional cardiologist with detailed information about vessel size and plaque size at every position along the vessel of interest, making this a suitable tool during the actual intervention.     

Angiographically uncertain left main coronary artery narrowings: correlation with multidetector computed tomography and intravascular ultrasound

Background Angiographic assessment of left main coronary artery (LMCA) stenosis is often difficult and unreliable. To date, intravascular ultrasound (IVUS) is used to determine the significance of lesions in patients with LMCA stenosis of uncertain significance. We aimed to prospectively show the ability of multidetector computed tomography (MDCT) to assess LMCA luminal and plaque dimensions, and to characterize atherosclerotic plaque, as compared to IVUS and quantitative coronary angiography (QCA), in patients with angiographically uncertain LMCA stenosis. Methods Twenty patients, with angiographically uncertain LMCA stenosis, underwent coronary evaluation with IVUS, QCA and 16-slice MDCT. Minimal lumen diameter (MLD), minimal lumen area (MLA), lumen area stenosis (LAS) and plaque burden (PB) were assessed. Results The MLD (median [interquartile range]) was 3.2 mm (2.5–3.7) by IVUS, 2.8 mm (2.3–3.3) by QCA (r = 0.52, P < 0.05), and 2.8 mm (2.5–3.8) by MDCT (r = 0.77, P < 0.01). MDCT estimated MLA as 10.7 mm² (7.1–12.6) Vs. 9.9 mm² (6.5–13.5) by IVUS (r = 0.93, P < 0.01). Very high correlations were observed between MDCT and IVUS in assessing LAS (mean ± SD) (25.8 ± 19.1% and 29.0 ± 24.9% respectively, r = 0.83, P < 0.01), and PB (49.2 ± 15.8% and 49.2 ± 19.7% respectively, r = 0.94, P < 0.01). MDCT assigned plaque as being non-calcified with a sensitivity of 100%, while calcified plaques with a sensitivity of 75%. Conclusion A high degree of correlation was found between MDCT and IVUS regarding the assessment of minimal lumen diameter and area, lumen area stenosis and plaque burden as well as plaque characterization in patients with angiographically borderline LMCA stenosis. Therefore, in patients selected for non-invasive coronary tree evaluation, MDCT may provide a valuable tool for the assessment, decision-making and follow-up of patients with uncertain LMCA disease.     

Accuracy of Stent Measurements Using ECG-Gated Greyscale Intravascular Ultrasound Images: A Validation Study

Greyscale intravascular ultrasound (IVUS) is an accurate tool for measuring stent dimensions and residual disease at the stent edge. Electrocardiographically (ECG)-gated IVUS is used in evolving second-generation IVUS systems, but this modality provides fewer greyscale cross-sectional images, and its accuracy to measure stent dimensions has not been assessed. This study was designed to validate the use of ECG-gated greyscale IVUS in measuring minimum stent area (MSA), stent length and reference dimensions compared to standard greyscale IVUS data. IVUS imaging was performed after drug-eluting stent implantation in 53 target lesions in 48 patients with acute coronary syndrome. The IVUS catheter was mechanically withdrawn at 0.5 mm/s, standard greyscale images were collected at 10 frames/s, and ECG-gated greyscale images were constructed from R-wave gated images. The MSA measured 6.20 ± 1.75 mm²vs. 5.98 ± 1.55 mm² on standard greyscale and ECG-gated greyscale IVUS, respectively (R² = 0.91, p = 0.005). The MSA position (R² = 0.66, p = 0.179) and stent length (R² = 0.99, p = 0.435) measurements were similar between modalities. Proximal reference vessel area was larger by ECG-gated IVUS, but proximal reference lumen and distal reference measurements were similar. Bland-Altman plots demonstrated good agreement between modalities. In conclusion, ECG-gated greyscale IVUS provides accurate and reliable measurements of stent length, area and reference segment plaque burden after stent implantation and is not inferior to standard greyscale IVUS. (E-mail: gsm18439@aol.com or gmintz@crf.org).     

Serial changes of minimal stent malapposition not detected by intravascular ultrasound: follow-up optical coherence tomography study

Morphologic changes of small-sized post-stent malapposition have not been sufficiently evaluated. We investigated serial changes of minimal post-stent malapposition with a follow-up optical coherence tomography (OCT) study. Post-stent OCT and intravascular ultrasound (IVUS) and follow-up OCT were performed in 26 patients with minimal post-stent malapposition. Serial changes of number and percent of malapposition struts, and mean extra-stent malapposition area were measured in OCT analysis. Zotarolimus-eluting stent (ZES), sirolimus-eluting stent (SES), and paclitaxel-eluting stent (PES) were deployed in 17, 7 and 2 patients, respectively. Mean durations of the follow-up OCT study were 5.7 ± 3.0 months. The minimal post-stent malapposition cannot be detected by the IVUS, but be visualized with an OCT examination. According to different drug-eluting stents, malapposed stent struts were defined as the struts with detachment from the vessel wall ≥160 μm for SES, ≥130 μm for PES, and ≥110 μm for ZES. The percent of malapposition struts significantly decreased from 12.2 ± 11.0% post-stent to 1.0 ± 2.2% follow-up (P < 0.001). There was a significant decrease in the mean extra-stent malapposition area from 0.35 ± 0.16 mm² post-stent to 0.04 ± 0.11 mm² follow-up (P < 0.001). Complete disappearance of stent malapposition was also observed in 22 (85%) patients. In conclusion, minimal stent malapposition which is not detectable by IVUS may disappear or decrease in follow-up OCT evaluation.     

Interstudy reproducibility of the second generation, Fourier domain optical coherence tomography in patients with coronary artery disease and comparison with intravascular ultrasound: a study applying automated contour detection

Recently, Fourier domain OCT (FD-OCT) has been introduced for clinical use. This approach allows in vivo, high resolution (15 micron) imaging with very fast data acquisition, however, it requires brief flushing of the lumen during imaging. The reproducibility of such fast data acquisition under intracoronary flush application is poorly understood. To assess the inter-study variability of FD-OCT and to compare lumen morphometry to the established invasive imaging method, IVUS. 18 consecutive patients with coronary artery disease scheduled for PCI were included. In each target vessel a FD-OCT pullback (MGH system, light source 1,310 nm, 105 fps, pullback speed 20 mm/s) was acquired during brief (3 s) injection of X-ray contrast (flow 3 ml/s) through the guiding catheter. A second pullback was repeated under the same conditions after re-introduction of the FD OCT catheter into the coronary artery. IVUS and OCT imaging was performed in random order. FD-OCT and IVUS pullback data were analyzed using a recently developed software employing semi automated lumen contour and stent strut detection algorithms. Corresponding ROI were matched based on anatomical landmarks such as side branches and/or stent edges. Inter-study variability is presented as the absolute difference between the two pullbacks. FD-OCT showed remarkably good reproducibility. Inter-study variability in native vessels (cohort A) was very low for mean and minimal luminal area (0.10 ± 0.38, 0.19 ± 0.57 mm², respectively). Likewise inter-study variability was very low in stented coronary segments (cohort B) for mean lumen, mean stent, minimal luminal and minimal stent area (0.06 ± 0.08, 0.07 ± 0.10, 0.04 ± 0.09, 0.04 ± 0.10 mm², respectively). Comparison to IVUS morphometry revealed no significant differences. The differences between both imaging methods, OCT and IVUS, were very low for mean lumen, mean stent, minimal luminal and minimal stent area (0.10 ± 0.45, 0.10 ± 0.36, 0.26 ± 0.54, 0.05 ± 0.47 mm², respectively). FD-OCT shows excellent reproducibility and very low inter-study variability in both, native and stented coronary segments. No significant differences in quantitative lumen morphometry were observed between FD-OCT and IVUS. Evaluating these results suggest that FD-OCT is a reliable imaging tool to apply in longitudinal coronary artery disease studies.     

In vivo volumetric analysis of coronary stent using optical coherence tomography with a novel balloon occlusion-flushing catheter: a comparison with intravascular ultrasound

Optical coherence tomography (OCT) is limited as an intravascular imaging tool because of interference with blood. This study tested a new balloon occlusion-flushing catheter for OCT scanning of stented coronary arteries and compared stent measurements between OCT and intravascular ultrasound (IVUS). Motorized pullback with OCT and IVUS was examined in coronary stents deployed in swine. Quantitative measurements were obtained and compared between both groups. In addition, stent strut thickness was compared among OCT, IVUS and actual measurement. The occlusion catheter successfully provided motorized pullback OCT images in the stented coronary arteries without any complications. There were no differences in calculated lumen volume. However, stent volumes were significantly smaller with OCT than with IVUS (p < 0.05). OCT significantly underestimated the stent strut thickness compared with the actual measurement. Although OCT underestimates the stent strut thickness, motorized pullback OCT imaging with the occlusion catheter can provide appropriate in-stent images in the porcine coronary arteries.     

Intra- and interobserver variability in detection and assessment of calcified and noncalcified coronary artery plaques using 64-slice computed tomography

Objective Multislice computed tomography (MSCT) is an emerging noninvasive technique for detecting coronary plaques. The present study investigated agreement in the detection and characterization of coronary plaques and reproducibility of volumetric analysis. Methods A total of 20 patients underwent MSCT coronary angiography using 64 * 0.5 mm detector collimation. Two readers independently visually evaluated all MSCT datasets for the presence of coronary plaques (n = 82 in 262 coronary segments) and then classified them as calcified, mixed and noncalcified. In addition, one of the readers also manually determined total volumes as well as calcified and noncalcified volumes of each plaque. After a period of at least 4 weeks the complete volumetric analysis was repeated. Results Interobserver agreement was good for detection of coronary plaques on the segment level (weighted κ = 0.88, 95% CI [0.76, 0.95]). However, there was only moderate interobserver agreement for plaques classification (unweighted κ = 0.45, 95% CI [0.35, 0.61]). Intraobserver agreement was good for plaque detection on segment level (weighted κ = 0.90, 95% CI [0.77, 0.96]), while it was moderate with respect to their characterization (unweighted κ = 0.65, 95% CI [0.55, 0.80]). There was moderate reproducibility for total plaque volume (limits of agreement = ±6 mm³ at a mean measured volume of 10 mm³ and = ±28 mm³ at a mean measured volume of 100 mm³). Variation of relative differences significantly decreased for total volume and noncalcified volume with increasing mean volume. Conclusions Detection and volumetry of plaques by means of MSCT shows good to moderate reproducibility. Agreement of volume measurements depends on plaque size. Variation of relative differences decrease with increasing mean plaque volume.     

Stent implant follow-up in intravascular optical coherence tomography images

The objectives of this article are (i) to utilize computer methods in detection of stent struts imaged in vivo by optical coherence tomography (OCT) during percutaneous coronary interventions (PCI); (ii) to provide measurements for the assessment and monitoring of in-stent restenosis by OCT post PCI. Thirty-nine OCT cross-sections from seven pullbacks from seven patients presenting varying degrees of neointimal hyperplasia (NIH) are selected, and stent struts are detected. Stent and lumen boundaries are reconstructed and one experienced observer analyzed the strut detection, the lumen and stent area measurements, as well as the NIH thickness in comparison to manual tracing using the reviewing software provided by the OCT manufacturer (LightLab Imaging, MA, USA). Very good agreements were found between the computer methods and the expert evaluations for lumen cross-section area (mean difference = 0.11 ± 0.70 mm²; r ² = 0.98, P < 0.0001) and the stent cross-section area (mean difference = 0.10 ± 1.28 mm²; r ² = 0.85, P value <  0.0001). The average number of detected struts was 10.4 ± 2.9 per cross-section when the expert identified 10.5 ± 2.8 (r ² = 0.78, P value < 0.0001). For the given patient dataset: lumen cross-sectional area was on the average (6.05 ± 1.87 mm²), stent cross-sectional area was (6.26 ± 1.63 mm²), maximum angle between struts was on the average (85.96 ± 54.23°), maximum, average, and minimum distance between the stent and the lumen were (0.18 ± 0.13 mm), (0.08 ± 0.06 mm), and (0.01 ± 0.02 mm), respectively, and stent eccentricity was (0.80 ± 0.08). Low variability between the expert and automatic method was observed in the computations of the most important parameters assessing the degree of neointimal tissue growth in stents imaged by OCT pullbacks. After further extensive validation, the presented methods might offer a robust automated tool that will improve the evaluation and follow-up monitoring of in-stent restenosis in patients.     

Comparative assessment of “plaque/media” change on three modalities of IVUS immediately after implantation of either everolimus-eluting bioresorbable vascular scaffold or everolimus-eluting metallic stent in Absorb II study

The purpose of the study to assess the comparability of immediate changes in plaque/media volume (PV) on three modalities of intravascular ultrasound (IVUS) after implantation of either bioresorbable vascular scaffold (BVS) or everolimus-eluting metallic stent (EES) in Absorb II Study. The two devices have different device volume and ultrasound backscattering that may interfere with the “plaque/media” assessed by three modalities on IVUS: grayscale, backscattering of radiofrequency and brightness function. In a multicenter randomized controlled trial, 501 patients with stable or unstable angina underwent documentary IVUS pre- and post- implantation. The change in plaque/media volume (PV) was categorized into three groups according to the relative PV change in device segment: PV “increased” >+5% (PVI), PV unchanged ±5% (PVU), and PV decreased <?5% (PVD). The change in PV was re-evaluated three times: after subtraction of theoretical device volume, after analysis of echogenicity based on brightness function. In 449 patients, 483 lesions were analyzed pre- and post-implantation. “PVI” was more frequently observed in BVS (53.8%) than EES group (39.4%), p?=?0.006. After subtraction of the theoretical device volume, the frequency of “PVI” decreased in both BVS (36.2%) and EES (32.1%) groups and became comparable (p?=?0.581). In addition, the percentage of “PVI” was further reduced in both device groups after correction for either radiofrequency backscattering (BVS 34.4% vs. EES 22.6%) or echogenicity (BVS 25.2% vs. EES 9.7%). PV change in device segment was differently affected by BVS and EES devices implantation due to their differences in device volume and ultrasound backscattering. It implies that the lumen volume was also artifactually affected by the type of device implanted. Comparative IVUS assessment of lumen and plaque/media volume changes following implantation of BVS and EES requires specific methodological adjustment.     

Diffusion-weighted imaging in normal prostate and differential diagnosis of prostate diseases

Background  During the past several years, the morbidities of prostate diseases have increased sharply all over the world. Diffusion-weighted imaging (DWI) is an MR-based technique that probes the function of tissues. We attempt to investigate the diagnostic value of DWI and apparent diffusion coefficient (ADC) in normal prostate gland and prostate diseases. Materials and methods  A total of 16 healthy volunteers, 9 prostate cysts, 29 benign prostatic hyperplasia (BPH), and 21 prostatic carcinoma (Pca) underwent DWI, respectively. Their DWI and ADC characteristics were analyzed, and the diagnositic and differential diagnositic values of DWI and ADC were summarized. All of the BPH and Pca received a histological diagnosis. Results  In DWI, the signal intensity of BPH nodule was nonhomogeneous and lower than that of the peripheral zone (PZ). Pca showed high signal intensity while the prostate cyst showed low intensity. The mean ADCs for the normal central gland, PZ, prostate cyst, BPH nodules, and Pca foci were (1.352 ± 0.052) × 10⁻³ mm²/s, (1.829 ± 0.071) × 10⁻³ mm²/s, (2.557 ± 0.084) × 10⁻³ mm²/s, (1.576 ± 0.101) × 10⁻³ mm²/s, and (0.934 ± 0.166) × 10⁻³ mm²/s, respectively (P = 0.000). Conclusions  Diffusion-weighted imaging and ADCs for the normal central gland, PZ, prostate cyst, BPH nodules, and Pca demonstrate significant differences, and those can be used in the diagnosis and differential diagnosis of the diseases of prostate.     

Optical Coherence Tomography Imaging: Novel Insights into the Vascular Response After Coronary Stent Implantation

Optical coherence tomography (OCT) is a high-resolution imaging technique that is increasingly used for intracoronary imaging to characterize coronary atherosclerotic plaques and vascular responses after coronary stent implantation. Introduction of optical frequency-domain imaging (OFDI; second generation OCT) has simplified practical use of this novel imaging modality resulting in a more widespread availability in interventional cardiology. Here we highlight recent insights into the acute and chronic vascular response after coronary stent implantation by OCT imaging. OCT provides cross-sectional images with approximately 10-fold higher resolution as compared to intravascular-ultrasound (IVUS), allowing for precise evaluation of tissue coverage and malapposition of coronary stent struts. More than 30 studies using OCT to compare vascular responses to different stents have now been reported. Recent studies have examined the relation between OCT-image characteristics and tissue composition around stent struts. OCT is used for evaluation of novel stent concepts, such as bioengineered stents and bioabsorbable stents, where it provides more accurate information than IVUS. While intracoronary OCT imaging is further developed, including faster 3D-OCT-image-reconstruction, larger OCT studies/registries with standardized analysis will provide more insights into clinical implications of observations from OCT-imaging after coronary stent implantation.     

In vivo comparison of lumen dimensions measured by time domain-, and frequency domain-optical coherence tomography, and intravascular ultrasound

Lumen dimensions measured by time-domain optical coherence tomography (TD-OCT) may be influenced by the hemodynamic effect of proximal balloon occlusion. Frequency-domain OCT (FD-OCT) does not require the interruption of blood flow. Therefore, we compared the coronary lumen dimensions measured by TD-OCT, FD-OCT, and intravascular ultrasound (IVUS) in both stented and non-stented segments. Twenty patients who underwent both IVUS and OCT imaging (10 for TD- and 10 for FD-OCT) after stent implantation were included. The maximum, minimum, and mean diameters and areas were measured at the proximal and distal stent edges, as well as 3 mm inside and 5 mm outside of both edges. The measurements inside stent showed no significant differences between IVUS and TD- or FD-OCT. The lumen mean diameters and areas measured by IVUS at 5 mm outside stent were similar to those measured by FD-OCT (Distal; 3.07 ± 0.7 vs 3.03 ± 0.7 mm, p = 0.08 and 7.80 ± 4.0 vs 7.72 ± 4.1 mm², p = 0.07, respectively. Proximal; 3.25 ± 0.7 vs 3.23 ± 0.7 mm, p = 0.09 and 8.78 ± 3.8 vs 8.65 ± 3.7 mm², p = 0.08, respectively), but were greater than those measured by TD-OCT (Distal; 2.75 ± 0.5 vs 2.29 ± 0.5 mm, p = 0.0001 and 6.15 ± 2.6 vs 4.38 ± 1.9 mm², p = 0.0002, respectively. Proximal; 3.27 ± 0.6 vs 2.69 ± 0.6 mm, p = 0.0001 and 8.64 ± 3.4 vs 6.12 ± 2.7 mm², p = 0.0001 respectively). The interaction between TD- and FD-OCT for lumen dimension measurements at 5 mm outside stent was statistically significant. Vessel dimension measurements were similar between IVUS and FD-OCT in native vessel unlike with TD-OCT. Therefore, we might adapt the IVUS criteria of lesion severity for percutaneous coronary intervention to FD-OCT.     

Comparative assessment of three drug eluting stents with different platforms but with the same biodegradable polymer and the drug based on quantitative coronary angiography and optical coherence tomography at 12-month follow-up

The aim of this study was to compare neointima proliferation in three drug-eluting stents (DES) produced by the same company (Balton, Poland) which are covered with a biodegradable polymer and elute sirolimus (concentration: 1.0 and 1.2 µg/mm²), but have different stent platforms and strut thickness: stainless steel Prolim^® (115 µm) and BiOSS LIM^® (120 µm) and cobalt-chromium Alex^® (70 µm). We analyzed data of patients with quantitative coronary angiography (QCA) and optical coherence tomography (OCT) at 12 months from BiOSS LIM Registry, Prolim Registry and Alex OCT clinical trial. There were 56 patients enrolled, in whom 29 Prolim^® stents were deployed, in 11—BiOSS LIM^® and in 16—Alex stents. The late lumen loss was the smallest in Prolim^® subgroup (0.26?±?0.17 mm) and did not differ from Alex^® subgroup (0.28?±?0.47 mm). This parameter was significantly bigger in BiOSS^® subgroup (0.38?±?0.19 mm; p?<?0.05). In OCT analysis there was no statistically significant difference between Prolim^® and Alex^® subgroups in terms of mean neointima burden (24.6?±?8.6 vs. 19.27?±?8.11%) and neointima volume (28.16?±?15.10 vs. 24.51?±?17.64 mm³). In BiOSS^® group mean neointima burden (30.9?±?6.2%) and mean neointima volume (44.9?±?4.9 mm³) were significantly larger. The morphological analysis revealed that in most cases in all groups the neointima was homogenous with plaque presence only around stent struts. In the QCA and OCT analysis regular DES (Prolim^® and Alex^®) obtained similar results, whereas more pronounced response from the vessel wall was found in the BiOSS^® subgroup.     

Optical coherence tomography criteria for defining functional severity of intermediate lesions: a comparative study with FFR

Fractional flow reserve (FFR) is the gold standard in the assessment of severity of the coronary stenosis. The aim of the study was to compare optical coherence tomography (OCT) obtained intermediate coronary lesions lumen areas measurements with FFR assessments, with the goal to develop an OCT threshold to identify significant coronary stenosis. 48 patients (mean age 65 ± 10 years) was enrolled for the study. Within this population, 71 intermediate coronary lesions were investigated using both FFR and OCT. High dose bolus of Adenosine (120 μg) was used to obtain coronary hyperemia. OCT imaging was performed using non-occlusive technique to assess minimal lumen area (MLA) and diameter. The OCT cut-off value that showed the best correlation with the FFR cut-off of 0.80 was the MLA less than 2.05 mm² (accuracy 87 %, sensitivity 75 %, specificity 90 %, p < 0.001). The study did not disclose any relationship between FFR value and the lesion length. Vessel size influenced the OCT cut-off values, with greater values being found in presence of arteries with a reference diameter greater than 3.0 mm. OCT derived minimal lumen area might be complementary to FFR measurement in identifying ischemia related lesions. Further studies are warranted to assess threshold values in relation to vessel size and location.     

Combined optical coherence tomography and intravascular ultrasound radio frequency data analysis for plaque characterization. Classification accuracy of human coronary plaques in vitro

This study was performed to characterize coronary plaque types by optical coherence tomography (OCT) and intravascular ultrasound (IVUS) radiofrequency (RF) data analysis, and to investigate the possibility of error reduction by combining these techniques. Intracoronary imaging methods have greatly enhanced the diagnostic capabilities for the detection of high-risk atherosclerotic plaques. IVUS RF data analysis and OCT are two techniques focusing on plaque morphology and composition. Regions of interest were selected and imaged with OCT and IVUS in 50 sections, from 14 human coronary arteries, sectioned post-mortem from 14 hearts of patients dying of non-cardiovascular causes. Plaques were classified based on IVUS RF data analysis (VH-IVUS^TM), OCT and the combination of those. Histology was the benchmark. Imaging with both modalities and coregistered histology was successful in 36 sections. OCT correctly classified 24; VH-IVUS 25, and VH-IVUS/OCT combined, 27 out of 36 cross-sections. Systematic misclassifications in OCT were intimal thickening classified as fibroatheroma in 8 cross-sections. Misclassifications in VH-IVUS were mainly fibroatheroma as intimal thickening in 5 cross-sections. Typical image artifacts were found to affect the interpretation of OCT data, misclassifying intimal thickening as fibroatheroma or thin-cap fibroatheroma. Adding VH-IVUS to OCT reduced the error rate in this study.     

Serial angiographic and intravascular ultrasound evaluation to interrogate the presence of late ��catch-up�� phenomenon after cypher? sirolimus-eluting stent implantation

Despite the expressive reduction in the intimal hyperplasia (IH) formation after DES implantation at the mid-term, late restenosis has been recently noticed. Our objective was to determine, by means of serial angiography (QCA) and intravascular ultrasound (IVUS) at two different time points, whether the occurrence of the "late catch-up" phenomenon occurs after sirolimus-eluting stent (SES) implantation. Thirty-eight non-complex patients treated with a single 18-mm SES who had systematic serial QCA and IVUS analyses at mean 8 and 20?months were enrolled. Primary endpoint is to evaluate the temporal course of IH formation after SES implantation, by comparing QCA in-stent late loss and IVUS percent IH obstruction between the invasive follow-ups. Mean cohort age was 59.3?years and 31.6% were diabetics. Baseline reference vessel diameter was 2.8 ± 0.4?mm and lesion length was 11.5 ± 3.5?mm. Left anterior descending artery was the most frequent target vessel (55.3%). Between 8 and 20?months, a non-significant increase in in-stent late loss from 0.10 ± 0.18 to 0.15 ± 0.30?mm (P?=?0.38) was observed. By IVUS, a slight increase in the percent IH obstruction (1.03 ± 2.13 to 1.76 ± 1.87%, P?=?0.12) was detected between the two evaluations. Interestingly, all the neoformed tissue accrued from 8 to 20?months accumulated in the distal portion of the stent. In the non-complex scenario, SES implantation was associated with a minimal, non-significant increase in the IH volume between 8 and 20?months.     

Evaluation with in vivo optical coherence tomography and histology of the vascular effects of the everolimus-eluting bioresorbable vascular scaffold at two years following implantation in a healthy porcine coronary artery model: implications of pilot results for future pre-clinical studies

To quantify with in vivo OCT and histology, the device/vessel interaction after implantation of the bioresorbable vascular scaffold (BVS). We evaluated the area and thickness of the strut voids previously occupied by the polymeric struts, and the neointimal hyperplasia (NIH) area covering the endoluminal surface of the strut voids (NIH_EV), as well as the NIH area occupying the space between the strut voids (NIH_BV), in healthy porcine coronary arteries at 2, 3 and 4?years after implantation of the device. Twenty-two polymeric BVS were implanted in the coronary arteries of 11 healthy Yucatan minipigs that underwent OCT at 2, 3 and 4?years after implantation, immediately followed by euthanasia. The areas and thicknesses of 60 corresponding strut voids previously occupied by the polymeric struts and the size of 60 corresponding NIH_EV and 49 NIH_BV were evaluated with both OCT and histology by 2 independent observers, using a single quantitative analysis software for both techniques. At 3 and 4?years after implantation, the strut voids were no longer detectable by OCT or histology due to complete polymer resorption. However, analysis performed at 2?years still provided clear delineation of these structures, by both techniques. The median [ranges] areas of these strut voids were 0.04 [0.03?C0.16] and 0.02 [0.01?C0.07] mm² by histology and OCT, respectively. The mean (±SD) thickness by histology and OCT was 220?±?40?and 120?±?20???m, respectively. The median [ranges] NIH_EV by histology and OCT was 0.07 [0.04?C0.20] and 0.03 [0.01?C0.08] mm², while the mean (±SD) NIH_BV by histology and OCT was 0.13?±?0.07?and 0.10?±?0.06?mm². Our study indicates that in vivo OCT of the BVS provides correlated measurements of the same order of magnitude as histomorphometry, and is reproducible for the evaluation of certain vascular and device-related characteristics. However, histology systematically gives larger values for all the measured structures compared to OCT, at 2?years post implantation.     

IVUS- Versus OCT-Guided Coronary Stent Implantation: a Comparison of Intravascular Imaging for Stent Optimization

Purpose of Review

Intravascular imaging provides improved diagnostic accuracy and optimization of percutaneous coronary interventions (PCI) compared with angiography alone. We review the latest literature on the predominant intravascular imaging modalities, intravascular ultrasound (IVUS), and optical coherence tomography (OCT).

Recent Findings

A number of recently published clinical studies evaluating OCT and IVUS use have demonstrated improved procedural and clinical outcomes over angiography. Recent literature also reports on novel potential applications of these technologies.

Summary

Intravascular imaging is an important diagnostic tool that augments angiography. IVUS has been the primary adjunctive intravascular imaging modality in interventional cardiology over the past three decades, while OCT is a newer modality of growing clinical importance. Both modalities augment angiography alone while having their own specific advantages and disadvantages.