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.

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.

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.

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.

Beneficial effects of rapid introduction of adaptive servo-ventilation in the emergency room in patients with acute cardiogenic pulmonary edema.

BACKGROUND: Adaptive servo-ventilation (ASV) at home has been used for patients with chronic heart failure. However, its effect on acute cardiogenic pulmonary edema (ACPE) is not clear. The aim of this study was to elucidate the effect of ASV use in the emergency room in patients with ACPE. METHODS: We enrolled 198 consecutive patients with ACPE. Eighty patients received standard therapies, such as oxygen inhalation and vasodilators (conventional therapy group), and 118 received ASV in addition to standard therapy (ASV therapy group). ASV was initiated in the emergency room immediately after diagnosis. The procedure was switched over from ASV to endotracheal intubation (ETI) when oxygenation was insufficient. RESULTS: The ETI rate in the ASV therapy group was significantly lower than that in the conventional therapy group (3% vs. 21%, p<0.01). The intensive care unit and/or high care unit length of stay in the ASV therapy group was also significantly shorter than that in the conventional therapy group (1.9±2.1 days vs. 5.3±6.8 days, p<0.01). Consequently, the hospitalization period in the ASV therapy group was shorter than that in the conventional therapy group (19.3±11.0 days vs. 26.3±16.6 days, p<0.01). CONCLUSION: In patients with ACPE, rapid introduction of ASV in the emergency room reduces the need for ETI and decreases the hospitalization period.

Contrast-enhanced ultrasound for the evaluation of acute renal infarction.

A 65-year-old male in the dilated phase of hypertrophic cardiomyopathy and with persistent atrial fibrillation was admitted to our hospital because of an episode of ventricular fibrillation following an appropriate shock from an implantable cardiac defibrillator (ICD). At admission, electrocardiography showed a normal sinus rhythm. He had complained of back pain 7 days after the ICD shock. Renal infarction was suspected, although computed tomography and magnetic resonance imaging could not be performed because of chronic renal failure and the presence of his ICD. We, therefore, used contrast-enhanced ultrasonography with a contrast agent to evaluate his acute kidney injury. This showed the left kidney contained a wedge-shaped area that was not enhanced by the contrast agent, indicating an area of infarction.

A calcified amorphous tumor that developed on both sides of the atrioventricular valve annulus.

We report a rare case of a hemodialysis patient with a calcified amorphous tumor (CAT) on both sides of the atrioventricular valve annulus. A 70-year-old female who had received hemodialysis for 23 years because of chronic glomerulonephritis presented to our hospital with acute heart failure. Echocardiography indicated the presence of mobile cardiac masses on the mitral valve and tricuspid valve annulus. We suspected the presence of a cardiac tumor or vegetation. The patient received 3 g/day sulbactam-ampicillin and 60 mg/day gentamicin. Surgery was performed on the 14th day after hospital admission. The patient underwent mitral valve replacement, tricuspid annuloplasty, and tumor resection. Based on the pathological findings, the cardiac tumor was diagnosed as a CAT.

Decreased Intrathoracic Impedance Associated With OptiVol Alert Can Diagnose Increased B-Type Natriuretic Peptide - MOMOTARO (Monitoring and Management of OptiVol Alert to Reduce Heart Failure Hospitalization) Study - .

BACKGROUND: Ambulatory measurement of intrathoracic impedance (ITI) with an implanted device may detect increases in pulmonary fluid retention early, but the clinical utility of this method is not well established. The goal of this study was to test whether conventional ITI-derived parameters can diagnose fluid retention that may cause early stage heart failure (HF). METHODS AND RESULTS: HF patients implanted with high-energy devices with OptiVol (Medtronic) monitoring were enrolled in this study. Patients were monitored remotely. At both baseline and OptiVol alert, patients were assessed on standard examinations, including analysis of serum brain natriuretic peptide (BNP). From April 2010 to August 2011, 195 patients from 12 institutes were enrolled. There were 154 primary OptiVol alert events. BNP level at the alerts was not significantly different from that at baseline. Given that ITI was inversely correlated with log BNP, we added a criterion specifying that the OptiVol alert is triggered only when ITI decreases by ≥4% from baseline. This change improved the diagnostic potential of increase in BNP at OptiVol alert (sensitivity, 75%; specificity, 88%). CONCLUSIONS: BNP increase could not be identified based on OptiVol alert. Decrease in ITI ≥4% compared with baseline, in addition to the alert, however, may be a useful marker for the likelihood of HF (Clinical trial info: UMIN000003351).

[Factors of the successful radiofrequency catheter ablation to the slow pathway in patients with uncommon atrioventricular nodal reentrant tachycardia].

We studied the clinical features and factors of successful catheter ablation for common and uncommon atrioventricular nodal reentrant tachycardia(AVNRT). The study population consisted of 41 consecutive patients, 33 with common type AVNRT (16 males mean age of 57.8 years), and 8 patients with uncommon type AVNRT (4 males, mean age of 57.1 years). In all patients with common type AVNRT, the earliest atrial activation during tachycardia was recorded at the His bundle region. The effective ablation sites were located in the medial septal area and all cases were successfully ablated without complication. In patients with uncommon type AVNRT, dual pathway was observed in 5 patients(63%) and triple pathway in 3 patients(38%). The earliest atrial activation during tachycardias was recorded at the ostium of the coronary sinus. Radiofrequency ablation therapy was performed during sinus rhythm in 5 patients, and during tachycardia in 3 others. The effective ablation sites were located at the posterior septal area around the coronary sinus ostium. All cases were successfully ablated without any major complication, but one case had second-grade atrioventricular block after ablation. There were no significant differences between the common and uncommon type AVNRT cases with regard to the therapeutic success rate, the mean application number or the total energy applied. However, the successful ablation sites were different between the two groups. We concluded that radiofrequency catheter ablation would be effective in patients with both common and uncommon types AVNRT. Selective ablation at the site of the retrograde slow pathway exit was the most important factor for successful catheter ablation for uncommon type AVNRT. However, it should be performed only after careful analysis, taking into account the complex mechanism of uncommon type AVNRT.