Deep Learning-Based Stenosis Quantification From Coronary CT Angiography

Background: Coronary computed tomography angiography (CTA) allows quantification of stenosis. However, such quantitative analysis is not part of clinical routine. We evaluated the feasibility of utilizing deep learning for quantifying coronary artery disease from CTA. Methods: A total of 716 diseased segments in 156 patients (66 ± 10 years) who underwent CTA were analyzed. Minimal luminal area (MLA), percent diameter stenosis (DS), and percent contrast density difference (CDD) were measured using semi-automated software (Autoplaque) by an expert reader. Using the expert annotations, deep learning was performed with convolutional neural networks using 10-fold cross-validation to segment CTA lumen and calcified plaque. MLA, DS and CDD computed using deep-learning-based approach was compared to expert reader measurements. Results: There was excellent correlation between the expert reader and deep learning for all quantitative measures (r=0.984 for MLA; r=0.957 for DS; and r=0.975 for CDD, p<0.001 for all). The expert reader and deep learning method was not significantly different for MLA (median 4.3 mm2 for both, p=0.68) and CDD (11.6 vs 11.1%, p=0.30), and was significantly different for DS (26.0 vs 26.6%, p<0.05); however, the ranges of all the quantitative measures were within inter-observer variability between 2 expert readers. Conclusions: Our deep learning-based method allows quantitative measurement of coronary artery disease segments accurately from CTA and may enhance clinical reporting.ope

Diagnostic Accuracy of a Novel On-site Virtual Fractional Flow Reserve Parallel Computing System

PURPOSE: To evaluate the diagnostic accuracy of a novel on-site virtual fractional flow reserve (vFFR) derived from coronary computed tomography angiography (CTA). MATERIALS AND METHODS: We analyzed 100 vessels from 57 patients who had undergone CTA followed by invasive FFR during coronary angiography. Coronary lumen segmentation and three-dimensional reconstruction were conducted using a completely automated algorithm, and parallel computing based vFFR prediction was performed. Lesion-specific ischemia based on FFR was defined as significant at ≤0.8, as well as ≤0.75, and obstructive CTA stenosis was defined that ≥50%. The diagnostic performance of vFFR was compared to invasive FFR at both ≤0.8 and ≤0.75. RESULTS: The average computation time was 12 minutes per patient. The correlation coefficient (r) between vFFR and invasive FFR was 0.75 [95% confidence interval (CI) 0.65 to 0.83], and Bland-Altman analysis showed a mean bias of 0.005 (95% CI -0.011 to 0.021) with 95% limits of agreement of -0.16 to 0.17 between vFFR and FFR. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 78.0%, 87.1%, 72.5%, 58.7%, and 92.6%, respectively, using the FFR cutoff of 0.80. They were 87.0%, 95.0%, 80.0%, 54.3%, and 98.5%, respectively, with the FFR cutoff of 0.75. The area under the receiver-operating characteristics curve of vFFR versus obstructive CTA stenosis was 0.88 versus 0.61 for the FFR cutoff of 0.80, respectively; it was 0.94 versus 0.62 for the FFR cutoff of 0.75. CONCLUSION: Our novel, fully automated, on-site vFFR technology showed excellent diagnostic performance for the detection of lesion-specific ischemia.ope

Generative adversarial network with radiomic feature reproducibility analysis for computed tomography denoising

Background: Most computed tomography (CT) denoising algorithms have been evaluated using image quality analysis (IQA) methods developed for natural image, which do not adequately capture the texture details in medical imaging. Radiomics is an emerging image analysis technique that extracts texture information to provide a more objective basis for medical imaging diagnostics, overcoming the subjective nature of traditional methods. By utilizing the difficulty of reproducing radiomics features under different imaging protocols, we can more accurately evaluate the performance of CT denoising algorithms. Method: We introduced radiomic feature reproducibility analysis as an evaluation metric for a denoising algorithm. Also, we proposed a low-dose CT denoising method based on a generative adversarial network (GAN), which outperformed well-known CT denoising methods. Results: Although the proposed model produced excellent results visually, the traditional image assessment metrics such as peak signal-to-noise ratio and structural similarity failed to show distinctive performance differences between the proposed method and the conventional ones. However, radiomic feature reproducibility analysis provided a distinctive assessment of the CT denoising performance. Furthermore, radiomic feature reproducibility analysis allowed fine-tuning of the hyper-parameters of the GAN. Conclusion: We demonstrated that the well-tuned GAN architecture outperforms the well-known CT denoising methods. Our study is the first to introduce radiomics reproducibility analysis as an evaluation metric for CT denoising. We look forward that the study may bridge the gap between traditional objective and subjective evaluations in the clinical medical imaging field. © 2023 The Author(s)ope

관상동맥 질환 평가를 위한 새로운 방법론 : 새로운 영상 획득 기법부터 심층학습기반 자동 정량화까지

의과학Cardiovascular disease remains the leading cause of mortality in the world. Coronary computed tomographic angiography (CTA) has emerged as a reliable noninvasive modality for the diagnosis of coronary artery disease (CAD). However, on-site evaluation of CAD is still a challenging problem. To solve this problem, this dissertation covers methods ranging from a new imaging acquisition technique to deep learning based automatic quantification. To obtain quality CTA, catheter-directed selective CTA (S-CTA) was developed in the preclinical model, and the clinical feasibility of S-CTA was validated in patients who had diagnosed CAD. S-CTA successfully produced an optimal luminal enhancement with an extremely low-dose of iodine. Automatic quantification was developed using convolutional neural networks (CNN). We successfully measured vascular minimal lumen area, diameter stenosis, and plaque volume with the proposed CNN model. When S-CTA was used for automatic quantification, the proposed CNN successfully captured intrinsic features of the contrast-enhanced lumen and calcified plaque better than C-CTA. S-CTA can be understood as an intraprocedural CTA modality under the combined-system that incorporates the coronary angiography system and a 320-detector row CT scanner. S-CTA enables a strategic stepwise approach for coronary catheterization and on-site evaluation for coronary stenosis.open박

In vivo detection of acute ischemic damages in retinal arterial occlusion with optical coherence tomography: A "prominent middle limiting membrane sign"

PURPOSE: To describe characteristic findings of acute retinal ischemic damage in optical coherence tomography. METHODS: Eighteen cases of acute retinal arterial occlusion with available fundus photography, optical coherence tomography, and/or fluorescein angiography in the early phase (<1 month) with more than 2 months follow-up were reviewed. A site-to-site analysis between optical coherence tomography morphology and correlating fundus images were done on each visit. RESULTS: Retinal opacities at first presentation were vague to mild opacity in four eyes, moderate (affecting visibility of underlying choroidal vessels) in seven, severe (yellow to whitish) in five, and very severe (chalky white) in two. These changes eventually disappear within 1 month (8 of 9 eyes). Inner retinal hyperreflectivity and a "prominent middle limiting membrane" in optical coherence tomography were consistently noticed up to 1 month showing regional correlation with the retinal opaque areas and was readily identified even in areas with vague or disappeared retinal opacities. Later, inner retinal atrophic changes replace these ischemic optical coherence tomography signs. CONCLUSION: A prominent middle limiting membrane sign is a useful indicator of acute ischemic retinal damage, especially in cases showing subtle or resolved retinal opacities before the onset of atrophic changes.ope

Contrast sensitivity measurement with 2 contrast sensitivity tests in normal eyes and eyes with cataract.

PURPOSE: To assess the reliability of and correlation between 2 contrast sensitivity tests in normal eyes and eyes with cataract. SETTING: Department of Ophthalmology, Yonsei University Hospital, Seoul, Korea. METHODS: The Vision Contrast Test System (wall-chart test) and Optec 6500 system (view-in test) were used to measure contrast sensitivity in normal eyes at 2 visits separated by 2 weeks and in eyes with cataract before and 2 months after cataract surgery. The test-retest reliability and correlation were calculated by the intraclass correlation coefficient (ICC), coefficient of repeatability (COR), and 95% range of difference using the Bland-Altman method. RESULTS: The study evaluated 40 normal eyes of 20 subjects and 44 eyes of 38 cataract patients. The repeatability of the 2 test methods was generally acceptable. The view-in test performed better than the wall-chart test in the ICC analysis (0.85 versus 0.65) but not in the COR analysis (+/-0.20 log versus +/-0.27 log). Correlation between the 2 tests was poor in both groups of eyes. The ceiling effect was greater with the wall-chart test. The floor effect occurred mainly in patients with cataract, in which it was greater preoperatively than postoperatively; at high frequency; and with the view-in test. CONCLUSION: Based on the ceiling and floor effect, the view-in test is better for detecting subtle contrast sensitivity changes in normal or near-normal eyes and the wall-chart test is useful in eyes with compromised vision. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentionedope

Clinical feasibility of catheter-directed selective intracoronary computed tomography angiography using an extremely low dose of iodine in patients with coronary artery disease

OBJECTIVE: This study aimed to evaluate the clinical feasibility of catheter-directed selective computed tomography angiography (S-CTA) in patients with coronary artery disease (CAD). METHODS: We prospectively enrolled 65 patients diagnosed with CAD who underwent conventional computed tomography angiography (C-CTA). C-CTA was performed with 60-90 mL of contrast medium (370 mg iodine/mL), whereas S-CTA was performed with 15 mL of contrast medium and 17.19 mg iodine/mL. Luminal enhancement range, homogeneity of luminal enhancement, image quality, plaque volume (PV), and percent aggregate plaque volume (%APV) were measured. Paired Student's t test, Wilcoxon rank-sum test, and Pearson's correlation coefficient were used to compare two methods. RESULTS: Luminal enhancement was significantly higher on S-CTA than on C-CTA (324.4 ± 8.0 Hounsfield unit (HU) vs. 312.0 ± 8.0 HU, p < 0.0001 in the per-vessel analysis). Transluminal attenuation gradient showed a significantly slower reduction pattern on S-CTA than on C-CTA (-0.65 HU/10 mm vs. -0.89 HU/10 mm, p < 0.0001 in the per-vessel analysis). Image noise was significantly lower on S-CTA than on C-CTA (39.6 ± 10.0 HU vs. 43.9 ± 9.4 HU, p < 0.0001). There was excellent correlation between S-CTA and C-CTA with respect to PV and %APV (r = 0.99, r = 0.98, respectively). CONCLUSIONS: S-CTA might be useful in facilitating atherosclerotic plaque analysis and providing guidance for complex lesions such as chronic total occlusion, particularly in cases in which on-site procedure planning is required. KEY POINTS: • Selective computed tomography angiography (S-CTA) can serve as an intraprocedural computed tomography angiography protocol. • S-CTA was performed with low dose of iodine compared with conventional computed tomography angiography. • S-CTA enables on-site atherosclerotic plaque analysis.restrictio

A fast seed detection using local geometrical feature for automatic tracking of coronary arteries in CTA.

We propose a fast seed detection for automatic tracking of coronary arteries in coronary computed tomographic angiography (CCTA). To detect vessel regions, Hessian-based filtering is combined with a new local geometric feature that is based on the similarity of the consecutive cross-sections perpendicular to the vessel direction. It is in turn founded on the prior knowledge that a vessel segment is shaped like a cylinder in axial slices. To improve computational efficiency, an axial slice, which contains part of three main coronary arteries, is selected and regions of interest (ROIs) are extracted in the slice. Only for the voxels belonging to the ROIs, the proposed geometric feature is calculated. With the seed points, which are the centroids of the detected vessel regions, and their vessel directions, vessel tracking method can be used for artery extraction. Here a particle filtering-based tracking algorithm is tested. Using 19 clinical CCTA datasets, it is demonstrated that the proposed method detects seed points and can be used for full automatic coronary artery extraction. ROC (receiver operating characteristic) curve analysis shows the advantages of the proposed method.ope

New insights into the pathoanatomy of diabetic macular edema: angiographic patterns and optical coherence tomography

PURPOSE: To describe the pathoanatomy of diabetic macular edema in optical coherence tomography and its correlation with fluorescein angiography patterns. METHODS: Sixty eyes of 56 patients were analyzed. Diabetic macular edema was classified into typical focal leakage (from microaneurysm), typical diffuse leakage (the capillary plexus), or combined/questionable leakage using fluorescein angiography and retinal thickness profiles. The leakage and pooling patterns in fluorescein angiography were matched to the corresponding optical coherence tomography images and analyzed. RESULTS: Focal leakage shows swelling predominantly in the outer plexiform layer (OPL). Deeply located microaneurysms directly leak into the loose fiber portion of OPL (Henle layer) through the "fluid conductivity barrier" (synaptic portion of OPL). Diffuse leakage caused swelling predominantly in the inner nuclear layer and secondarily in the OPL. The deep capillary plexus is located between the two "fluid barriers" (inner plexiform layer and OPL); thus, diffuse leakage is primarily related with swelling in the inner nuclear layer. In the combined/questionable leakage, partial sections consisting of inner nuclear layer swelling and much larger areas of OPL/outer nuclear layer swelling are noticed. CONCLUSION: Based on the concept of the fluid conductivity barrier, we revealed a correlation between the intraretinal location of the leakage source and where the fluid accumulated within the retinal layers.ope

Determination of macular hole size in relation to individual variabilities of fovea morphology

PURPOSE: To determine the preoperative anatomic factors in macular holes and their correlation to hole closure. METHODS: Forty-six eyes with consecutive unilateral macular hole who had undergone surgery and followed up for at least 6 months were enrolled. Optical coherence tomography images and best-corrected visual acuity (BCVA) within 2 weeks prior to operation and 6 months after surgery were analyzed. The maximal hole dimension, foveal degeneration factors (inner nuclear layer cysts, outer segment (OS) shortening) and the widest foveolar floor size of the fellow eyes were measured. For overcoming preoperative individual variability of foveal morphology, an 'adjusted' hole size parameter (the ratio between the hole size and the fellow eye foveolar floor size) was used based on the fact that both eyes were morphologically symmetrical. RESULTS: Mean preoperative BCVA (logMAR) was 1.03±0.43 and the mean postoperative BCVA was 0.50±0.38 at 6 months. Preoperative BCVA is significantly associated with postoperative BCVA (P=0.0002). The average hole diameter was 448.9±196.8 μm and the average fellow eye foveolar floor size was 461.3±128.4 μm. There was a correlation between hole diameter and the size of the fellow eye foveolar floor (Pearson's coefficient=0.608, P<0.0001). The adjusted hole size parameter was 0.979±0.358 (0.761-2.336), which was a strong predictor for both anatomic (P=0.0281) and visual (P=0.0016) outcome. CONCLUSION: When determining the extent of preoperative hole size, we have to take into consideration the foveal morphologic variations among individuals. Hole size may be related to the original foveal shape, especially in relation to the centrifugal retraction of the foveal tissues.ope