Content-based image retrieval for the diagnosis of myocardial perfusion imaging using a deep convolutional autoencoder.

BACKGROUND: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) plays a crucial role in the optimal treatment strategy for patients with coronary heart disease. We tested the feasibility of feature extraction from MPI using a deep convolutional autoencoder (CAE) model. METHODS: Eight hundred and forty-three pairs of stress and rest myocardial perfusion images were collected from consecutive patients who underwent cardiac scintigraphy in our hospital between December 2019 and February 2022. We trained a CAE model to reproduce the input paired image data, so as the encoder to output a 256-dimensional feature vector. The extracted feature vectors were further dimensionally reduced via principal component analysis (PCA) for data visualization. Content-based image retrieval (CBIR) was performed based on the cosine similarity of the feature vectors between the query and reference images. The agreement of the radiologist's finding between the query and retrieved MPI was evaluated using binary accuracy, precision, recall, and F1-score. RESULTS: A three-dimensional scatter plot with PCA revealed that feature vectors retained clinical information such as percent summed difference score, presence of ischemia, and the location of scar reported by radiologists. When CBIR was used as a similarity-based diagnostic tool, the binary accuracy was 81.0%. CONCLUSION: The results indicated the utility of unsupervised feature learning for CBIR in MPI.

Using a Visual Turing Test to Evaluate the Realism of Generative Adversarial Network (GAN)-Based Synthesized Myocardial Perfusion Images.

As the quality of image generation by deep learning increases, it is becoming difficult to discern its authenticity from the image alone. Currently, generative models represented by generative adversarial networks (GAN) are increasingly utilized in the research field of cardiology, and their potential risks are also being pointed out. In this context, we assessed whether expert cardiologists can detect synthesized myocardial perfusion images (MPI) generated by GAN as fake. A total of 1448 polar maps collected from consecutive patients who underwent MPI for known or suspected coronary artery disease from January 2020 to December 2021 were used for the analysis. A deep convolutional GAN was trained on the polar maps to synthesize realistic MPI. The realism of the generated images in terms of human perception was evaluated by the visual Turing test (VTT) on our original website. The average correct answer rate of the VTT was only 61.1% with a standard deviation of 21.5, but this improved to 80.0±15.8 (%) in the second trial when given the clue information. In the era of machine intelligence and virtual reality, digital literacy is becoming more necessary for healthcare professionals to identify deepfakes.

Bepridil monotherapy failed to prevent coronary vasospasm in a Brugada syndrome patient.

Coronary vasospasm sometimes coexists with Brugada syndrome (BrS) and is reportedly associated with poor prognosis. Although calcium channel blockers are considered first-line drugs to prevent coronary vasospasm, they also have the potential to induce ST elevation and ventricular fibrillation (VF) in BrS. Therefore, the optimal medication for such a complicated case is still underdetermined. We report a male patient who presented with VF due to BrS, which was later found to have coexisted with coronary vasospasm. He was treated with low-dose bepridil expecting both its anti-arrhythmic and vasodilatory effects, but a later acetylcholine provocation test showed no suppression of vasospasm. Based on these results, we decided to add nitrates to the medication. This case report illustrates that drug selection needs caution in BrS when complicated with vasospastic angina and that bepridil monotherapy may not be sufficient to suppress coronary vasospasm in such cases.

Image similarity-based cardiac rhythm device identification from X-rays using feature point matching.

AIMS: Identifying the manufacturer and the type of cardiac implantable electronic devices (CIEDs) is important in emergent clinical settings. Recent studies have illustrated that artificial neural network models can successfully recognize CIEDs from chest X-ray images. However, all existing methods require a vast amount of medical data to train the classification model. Here, we have proposed a novel method to retrieve an identical CIED image from an image database by employing the feature point matching algorithm. METHODS AND RESULTS: A total of 653 unique X-ray images from 456 patients who visited our pacemaker clinic between April 2012 and August 2020 were collected. The device images were manually square-shaped, and was thereafter resized to 224 × 224 pixels. A scale-invariant feature transform (SIFT) algorithm was used to extract the keypoints from the query image and reference images. Paired feature points were selected via brute-force matching, and the average Euclidean distance was calculated. The image with the shortest average distance was defined as the most similar image. The classification performance was indicated by accuracy, precision, recall, and F1-score for detecting the manufacturers and model groups, respectively. The average accuracy, precision, recall, and F-1 score for the manufacturer classification were 97.0%, 0.97, 0.96, and 0.96, respectively. For the model classification task, the average accuracy, precision, recall, and F-1 score were 93.2%, 0.94, 0.92, and 0.93, respectively, all of which were higher than those of the previously reported machine learning models. CONCLUSION: Feature point matching is useful for identifying CIEDs from X-ray images.

Three-Dimensional Reconstruction of Pacemaker Lead Trajectory From Orthogonal Chest X-Rays: A Proof of Concept.

Understanding the lead trajectory is important in preventing complications after cardiac rhythm device implantation. In this report, we sought to reconstruct the three-dimensional (3D) shape of a pacing lead from radiographs taken at 90-degree angles. All image data were obtained from a 65-year-old male patient, who underwent pacemaker implantation at our hospital due to third-degree atrioventricular block in 2016. Both frontal and lateral chest X-rays were taken just after the device implantation (supine position) and on the post-procedural day 1 (upright position), respectively. Fluorine-18-fluorodeoxyglucose positron emission tomography/CT was performed 75 days after the pacemaker implantation for the diagnosis of cardiac sarcoidosis. Contours of the ventricular leads were manually traced in each X-ray image and saved as Scalable Vector Format (SVG) files using the GNU Image Manipulation Program (GIMP). The 3D reconstruction was performed on Blender 2.93, which is an open-source computer graphics software. The lead trajectory could be reconstructed from bidirectional radiographs, which may allow for further investigation of the 3D shape change of the pacemaker leads.

Control of Emissive Excited States of Silver(I) Halogenido Coordination Polymers by a Solid Solution Approach.

Luminescent silver(I) halogenido coordination polymers [Ag2X2(PPh3)2(bpy)] n (X = I, Br, Cl) have been prepared. The iodido and bromido complexes exhibit strong blue phosphorescence assignable to the 3π-π*-excited-state of bpy, whereas the chlorido complex shows luminescence thermochromism due to the π-π*-state of bpy and charge transfer from the {Ag2Cl2} core to the bpy π*-orbital. Taking advantage of their structural similarities, we prepared a series of mixed-halogenido silver(I) complexes [Ag2(X xX'(1- x))2(PPh3)2(bpy)] n (X, X' = I, Br, Cl) at varying molar fractions as solid solutions. The mixed-halogenido complexes are as strongly luminescent as their parent complexes. The detailed study of their structure and emissive properties revealed smooth energy migration between the luminescent units and modification of the luminescence properties based on the planarity of bpy.

Beneficial effects of adaptive servo-ventilation therapy on readmission and medical costs in patients with chronic heart failure.

Adaptive servo-ventilation (ASV) therapy is a novel modality of noninvasive positive pressure ventilation and is now widely utilized to treat patients with chronic heart failure (CHF). However, there has been no clinical study of the effect of ASV therapy on readmission and cost-effectiveness for the treatment of CHF. The present study was conducted to evaluate the clinical efficacy and cost-effectiveness of home ASV therapy in 45 patients with a history of two or more admissions a year for worsening CHF. Seven patients refused to undergo chronic ASV therapy and three died. Thus, 35 patients were eventually enrolled in the present study. New York Heart Association class (2.8 ± 0.4 versus 2.3 ± 0.5, p < 0.001), log plasma B-type natriuretic peptide level (2.53 ± 0.44 versus 2.29 ± 0.40 pg/mL, p < 0.0001), left atrial dimension (47.5 ± 7.0 versus 44.9 ± 7.6 mm, p = 0.014), and mitral regurgitation area ratio (20.3 ± 12.1 versus 16.9 ± 8.9%, p = 0.007) decreased significantly after 12 months of ASV therapy. The frequency of hospitalization after ASV was significantly lower than before ASV (1.0 ± 1.0 versus 2.3 ± 0.5 times/year/patient, p < 0.0001). ASV also decreased the duration of hospitalization from 64.4 ± 46.5 to 22.8 ± 27.5 days/year/patient (p < 0.0001). Consequently, the total medical costs were reduced by 37% after ASV (1.95 ± 1.37 versus 3.11 ± 1.75 million yen/patient, p = 0.003). ASV therapy reduced readmissions and medical costs in patients with CHF.

Clinical Usefulness of Coronary Flow Reserve Ratio for the Detection of Significant Coronary Artery Disease on 13N-Ammonia Positron Emission Tomography.

BACKGROUND: This study aimed to evaluate the diagnostic performance of coronary flow reserve (CFR), hyperemic myocardial blood flow (hMBF), and CFR ratio for detecting significant coronary artery disease (CAD) on 13N-ammonia positron emission tomography (PET).Methods and Results:We analyzed 63 patients (mean age, 71±9 years; 43 males) with suspected CAD who underwent both pharmacological stress/rest 13N-ammonia PET and coronary angiography. CFR and hMBF for PET were calculated automatically using quantitative PET software, and the CFR ratio was defined as the ratio of per-vessel CFR to maximum CFR in a standard 17-segment model. We compared the diagnostic performance among the 3 quantitative values. In the per-vessel analysis, 55 vessels were diagnosed as significant CAD (≥70% stenosis and/or fraction flow reserve ≤0.8). CFR, hMBF, and CFR ratio of significant CAD were significantly lower than for non-significant CAD (1.85±0.69 vs. 2.38±0.69; P<0.01, 1.67±0.54 vs. 2.19±0.52 mL·min-1·g-1; P<0.01, and 0.66±0.15 vs. 0.82±0.09; P<0.01, respectively). In the receiver-operating characteristic curve analysis, CFR, hMBF, and CFR ratio had areas under the curve of 0.71, 0.75, and 0.85 respectively, and the CFR ratio was significantly higher than CFR and hMBF (P<0.05). The sensitivity, specificity, and accuracy of the CFR ratio with an optimal cutoff value of 0.75 were 75%, 85%, and 82%, respectively. CONCLUSIONS: Clinically, the CFR ratio in 13N-ammonia PET was more effective in detecting significant CAD.

Isolated Left Atrial Infective Mural Endocarditis.

A 52-year-old man presented with a fever and malaise. Transthoracic echocardiogram was performed because of a holosystolic murmur, which showed mitral valve prolapse and a regurgitation jet toward the posterior wall of the left atrium. There was no apparent vegetation at any valves. Blood cultures were positive for Streptococcus mitis/oralis. Transesophageal echocardiogram revealed vegetation only at the posterior wall of the left atrium exposed to the mitral regurgitant jet. We diagnosed this condition as infective mural endocarditis. This case highlighted the need for a detailed observation of the valves and the atrial wall when infective endocarditis is suspected.

Favorable effects of early tolvaptan administration in very elderly patients after repeat hospitalizations for acute decompensated heart failure.

Tolvaptan (TLV) is an oral selective vasopressin 2 receptor antagonist that acts on the distal nephrons, causing a loss of electrolyte-free water. To date, its early administration in very elderly patients after repeat hospitalizations for acute decompensated heart failure (ADHF) despite receiving optimal medical therapy has not been evaluated. Fifty-six ADHF patients who were >80 years old and had been repeatedly hospitalized were retrospectively enrolled in this study. Twenty-five patients (14 men; mean age 86.7 ± 5.3 years; control group) received standard therapy and 31 patients (15 men; mean age 85.5 ± 4.5 years; TLV group) received oral TLV within 24 h of admission. The rate of worsening renal function was significantly lower in the TLV group than in the control group (13 vs. 40%, P < 0.05). The duration of the return to body weight at a steady state was significantly shorter in the TLV group (5.3 ± 2.8 days) than in the control group (13.9 ± 9.2 days, P < 0.01). Consequently, the hospitalization period in the TLV group (13.5 ± 5.9 days) was significantly shorter than that in the control group (24.7 ± 12.3 days, P < 0.01). In conclusion, the early administration of TLV to very elderly patients who underwent repeat hospitalizations for ADHF resulted in immediate decongestion and thus reduced the hospitalization period with a lower incidence of worsening renal function.

Long-Term (>10 Years) clinical outcomes of first-in-human biodegradable poly-l-lactic acid coronary stents: Igaki-Tamai stents.

BACKGROUND: The purpose of this study was to evaluate the long-term safety of the Igaki-Tamai stent, the first-in-human fully biodegradable coronary stent made of poly-l-lactic acid. METHODS AND RESULTS: Between September 1998 and April 2000, 50 patients with 63 lesions were treated electively with 84 Igaki-Tamai stents. Overall clinical follow-up (>10 years) of major adverse cardiac events and rates of scaffold thrombosis was analyzed together with the results of angiography and intravascular ultrasound. Major adverse cardiac events included all-cause death, nonfatal myocardial infarction, and target lesion revascularization/target vessel revascularization. During the overall clinical follow-up period (121 ± 17 months), 2 patients were lost to follow-up. There were 1 cardiac death, 6 noncardiac deaths, and 4 myocardial infarctions. Survival rates free of all-cause death, cardiac death, and major adverse cardiac events at 10 years were 87%, 98%, and 50%, respectively. The cumulative rates of target lesion revascularization (target vessel revascularization) were 16% (16%) at 1 year, 18% (22%) at 5 years, and 28% (38%) at 10 years. Two definite scaffold thromboses (1 subacute, 1 very late) were recorded. The latter case was related to a sirolimus-eluting stent, which was implanted for a lesion proximal to an Igaki-Tamai stent. From the analysis of intravascular ultrasound data, the stent struts mostly disappeared within 3 years. The external elastic membrane area and stent area did not change. CONCLUSION: Acceptable major adverse cardiac events and scaffold thrombosis rates without stent recoil and vessel remodeling suggested the long-term safety of the Igaki-Tamai stent.

[Pulseless arrest in an elderly patient treated with intravenous tissue plasminogen activator for cardioembolic ischemic stroke].

A 77-year-old woman, who had a history of rheumatic mitral stenosis with atrial fibrillation (AF), was referred and admitted to our hospital because of a transient ischemic attack at 4: 55 p.m.. She had taken warfarin for over 10 years, but her condition was not well controlled on admission. At 8: 30 p.m., she had acute ischemic stroke with right facial palsy, right hemiparesis and slurred speech. At 10: 35 p.m., she was treated with intravenous tissue plasminogen activator (t-PA) and her neurological deficits almost fully recovered by 0: 05 a.m. (90 min after t-PA started). At 0: 08 a.m., she collapsed due to sudden pulseless arrest. Using advanced life support, she soon recovered with no complications. After mitral valve replacement and left atrial appendectomy, she was discharged with a modified Rankin scale 0 at day 40. To the best of our knowledge, this is the first case report showing pulseless arrest immediately after treatment with t-PA in an elderly patient with ischemic stroke. Left insular injury seemed to be a crucial mechanism of pulseless arrest in this case.