Computed Tomography Pulmonary Angiography Research Articles

Spectral analysis of non-contrast fluoroscopy for evaluation of pulmonary perfusion: Feasibility and sensitivity testing with a phantom.

Oscillating x-ray attenuation in the lungs provides an opportunity to evaluate pulmonary perfusion without contrast. Recent intensity-based methods have been compared to pulmonary scintigraphy and CT angiography but lack rigorous phantom studies. A new method to quantify the periodic signal amplitude was employed using spectral analysis. Performance was characterized using a water phantom capable of creating an oscillating x-ray attenuation at physiologic amplitudes. Feasibility in detecting abnormal perfusion was performed on a volunteer with pulmonary vascular disease and compared to pulmonary angiography, the clinical gold standard. For each fluoroscopic acquisition, the normalized temporal signal from each pixel was decomposed into its frequency components using Fourier transformation, and the spectral amplitude, defined as the x-ray pulsatility index (XPI), was determined at the desired frequency using a band-pass filter. XPI was displayed as a pixel-wise parametric colormap. Based on XPI maps generated using two human volunteers, a water bath phantom was constructed with a fluctuating fluid height and a 1cm diameter pulsatility defect. Contrast-to-noise (CNR) of the defect was measured using fluoroscopy images acquired at variable fluid height fluctuation (0.1-1.9mm) and oscillation frequency (30-60bpm). Various sampling frame rates (3-30 fps) and acquisition durations (1.8-8s) using truncated datasets were reconstructed from full datasets. Fluoroscopic images were obtained in a patient just prior to pulmonary angiography in the same projection. XPI maps in human subjects showed high signal to background contrast with high central XPI measuring up to 0.5. Phantom experiments revealed CNR was linearly correlated to fluid height change (r2 =0.998). CNR is proportional to increasing sampling frame rate and increasing acquisition duration as expected with Fourier analysis. XPI map displayed multifocal perfusion defects in good agreement with pulmonary angiography. Spectral analysis is an accurate and sensitive method to detect small changes in periodic x-ray attenuation using a short fluoroscopic acquisition. This method demonstrated good agreement to pulmonary angiography and shows promise for clinical imaging of pulmonary perfusion using standard fluoroscopic methods.

Multimodality Fusion Method Based on Multiview Subspace Clustering for Pulmonary Embolism Diagnosis.

Pulmonary embolism (PE) is an important clinical disorder that will result in lung tissue damage or low blood oxygen levels, which need early diagnosis and timely treatment. While computed tomographic pulmonary angiography (CTPA) is the gold standard to diagnose PE, previous studies have verified the effectiveness of combing CTPA and EMR data in computer-aided PE detection or diagnosis. In this paper, we proposed a multimodality fusion method based on multi-view subspace clustering guided feature selection (MSCUFS). The extracted high-dimensional image and EMR features are firstly selected and fused by the MSCUFS, and then are feed into different machine learning models with different fusion strategy to construct the PE classifier. The experiment results showed that the joint fusion strategy with MSCUFS achieved best AUROC of 0.947, surpassing other early fusion and late fusion models. The comparison between single modality and multimodality also illustrated the effectiveness of the proposed method.

Video assisted thorascopic assisted correction of left partial anomalous pulmonary venous connection: one case report

IntroductionThe left partial anomalous pulmonary vein connection is a rare congenital heart disease, especially with intact atrial septum. Now we reported a case of the left superior pulmonary vein drainage to left innominate vein through a vertical vein, and corrected with video assisted thoracoscopy.Case presentationA-59-years old man diagnosed left anomalous partial pulmonary vein connection with presentation of short breathiness and palpation, and diagnosed with computer tomography pulmonary angiography. The operation was carried out under video assisted thoracoscopy with one manipulation incision and one observational incision, the vertical vein was dissected and anastomosis with left atrial appendage. The patients recovered smoothly and postoperative CTPA showed anastomosis ostium was unobstructed.ConclusionThe left lateral thoracotomy and video assisted thoracoscopic surgery is a feasible for correction of left PAPVC with intact interatrial septum without using CPB.

Overuse of Computed Tomography Pulmonary Angiography and Low Utilization of Clinical Prediction Rules in Suspected Pulmonary Embolism Patients at a Regional Australian Hospital.

A pulmonary embolism (PE) is an obstruction in the pulmonary arterial system and may include non-specific signs and symptoms. Clinical prediction rules (CPRs) assess the pretest probability (PTP) of a PE to prevent the overuse of computed tomography pulmonary angiography (CTPA). CTPA overuse results in patient harm and health system waste. This study aimed to evaluate CTPA usage in an Australian regional hospital through analyzing CTPA encounters. A retrospective chart analysis was undertaken of 100 CTPAs conducted at an Australian regional hospital from April to May 2023. Analysis was undertaken for parameters including risk factors, signs and symptoms, investigations, and the use of CPRs. Overall, 86% of patients had signs and/or symptoms of a PE within a week of examination, and 6% of the population had signs of deep vein thrombosis. More than half of the population had no risk factors, while the most prevalent risk factors were a recent history of immobilization/trauma and/or having surgery that required general anesthesia in the last 4 weeks. The most common co-morbidity was chronic lung disease (11%). For the pre-test diagnostic workup, the ECG was the most ordered investigation. The Wells' score was used at 10%, while most patients did not have any CPRs applied. The prevalence of PEs discovered on CTPAs was 9%. CPRs were under-utilized in this Australian regional hospital. The D-dimers for ruling out subjects with low PTP derived from CPRs were also underused. This led to the inappropriate overordering of CTPAs, resulting in negative implications for patients and unnecessary costs to the health system.

Pediatric pulmonary thromboembolism: a 3-year Canadian Pediatric Surveillance Program study

BackgroundPediatric pulmonary embolism (PE) is a rare event associated with significant morbidity and mortality. Awareness of clinical presentation and practices unique to children may aid clinicians in prompt identification and treatment. ObjectivesTo describe the incidence, risk factors, clinical presentation, diagnostic and therapeutic practices, and short-term outcomes of pediatric PE. MethodsWe conducted a 3-year national surveillance study through the Canadian Pediatric Surveillance Program. Over 2800 pediatric specialists and subspecialists were contacted monthly from 2020 to 2022 and requested to report all new cases of PE in patients up to 18 years of age. Case-specific data were obtained through voluntary completion of a detailed questionnaire. ResultsFifty-eight cases (78% female, n = 45) were reported (2.4 cases per million children), with rates highest in adolescents 15 to 18 years (6.6 cases per million). Detailed information, available for 31 (53%) cases, documented at least 1 risk factor in 28 (90%) cases; 24 (77%) patients presented with 2 or more symptoms. Computed tomography pulmonary angiography was used for diagnostic confirmation in 25 (81%) cases. Anticoagulation was initiated in 24 (77%) of 31 cases; fewer than 5 patients underwent thrombolysis or surgical interventions. Of 28 patients who received therapeutic interventions, 8 (29%) experienced treatment-related complications. Fewer than 5 mortalities were reported. ConclusionPediatric PE is a rare event, with female adolescents at the highest risk. Although the presentation is often nonspecific, clinicians should maintain a high index of suspicion, particularly in patients with risk factors and when other diagnoses that may explain symptoms have been excluded.

Efficacy of pulse oximetry for early diagnosis of pulmonary embolism after total knee arthroplasty

IntroductionEarly diagnosis and aggressive treatment of pulmonary embolism (PE) are crucial for preventing severe complications after total knee arthroplasty (TKA). This study aimed to examine the efficacy of measuring oxygen saturation (SpO2) using a pulse oximeter for early diagnosis of PE after total knee arthroplasty (TKA).Materials and methodsWe consecutively examined 1645 patients who underwent TKA between January 2015 and November 2019. Postoperative SpO2 was measured with a pulse oximeter, which was stopped if SpO2 was maintained at ≥ 95% until postoperative day 2 (POD2). To diagnose PE, computed tomographic pulmonary angiography (CTPA) was performed for specific indications, including persistently low SpO2 < 95% (group 1), sudden decrease in SpO2 (group 2), and decrease in SpO2 after POD3 with presenting symptoms (group 3). Also, we divided the patients into unilateral, simultaneous and sequential TKA groups and compared the results with specific statistical techniques.ResultsOf the 1645 patients who underwent TKA, there were 20 patients with PE (1.2%), and symptomatic PE was observed in only 4 patients (0.24%). CTPA was performed in 58 (3.5%) patients, of whom 20 were diagnosed with PE. In groups 1 (n = 34), 2 (n = 21), and 3 (n = 3), CTPA was performed 2.4, 2.6, and 8.3 days after TKA, respectively, and 12, 8, and 0 patients were diagnosed with PE, respectively. Of the 782, 416, and 447 unilateral, simultaneous, and sequential (done in same admission with interval 1 or 2 weeks) patients with TKA, 38, 18, and 2 received CTPA, and 13, 6, and 1 were diagnosed with PE, respectively. All patients diagnosed with PE have persistently low SpO2 < 95% (group 1), or sudden decrease in SpO2 (group 2) until POD2. Of the patients diagnosed with PE, SpO2 decreased without the presentation of symptoms in 16 patients (11 and 5 from groups 1 and 2, respectively) and with the presentation of symptoms, such as mild dyspnea and chest discomfort, in 4 patients (1 and 3 from groups 1 and 2, respectively).ConclusionsMeasuring SpO2 using a pulse oximeter until POD2 was an effective method for early diagnosis of PE after TKA. No case of morbidity or mortality was observed after early diagnosis with early stage CTPA and management of PE. We recommend measuring SpO2 with a pulse oximeter for early diagnosing of PE in TKA.

Optimizing emergency department imaging utilization for pulmonary emboli: A study on the effects of IV contrast rationing

PurposeTo study the impact of a contrast mitigation protocol on imaging utilization for pulmonary embolism (PE) in the emergency department (ED). Material and methodsMedical records of ED patients with suspected PE who underwent CT pulmonary angiography (CTPA) or ventilation-perfusion (VQ) scans were analyzed in control (3/15/22–4/15/22) and test (5/15/22–6/15/22) periods. The test period included a contrast mitigation protocol due to a global iodinated contrast shortage (05/2022–06/2022). Out of 610 scans, 28 were excluded for non-PE indications. Patient demographics, time metrics, and imaging reports were recorded. ResultsAmong 11,019 ED visits, there were 582 imaging events for suspected PE. The test period exhibited a significantly lower imaging rate of 4.16 % compared to 6.54 % in the control period (p < 0.001). CTPA usage decreased by 47.73 %, while VQ scan usage increased by 775.00 % during the test period. Test period positivity rate was 0.82 %, with CTPA at 0.58 % (1/173) and VQ scan at 1.43 % (1/70). In the control period, the positivity rate was 0.29 %, with CTPA at 0.30 % (1/331) and VQ scan at 0.00 % (0/8). Previous hospitalization history was significantly higher in the test period (70/243 vs. 39/339, p < 0.001). The positivity rates between the two periods showed no significant difference (p = 0.57). There were no significant differences in ED length of stay and image acquisition times. ConclusionThe contrast mitigation protocol reduced CTPA use, increased VQ scans, and maintained positivity rates and image acquisition times. However, concerns persist about unnecessary imaging and low positivity rates, necessitating further research to optimize PE diagnostic algorithms.

Chronic thromboembolic pulmonary hypertension in a patient with myxoma of the heart and thrombophilia of mixed genesis

Objective. To describe the clinical case of a young patient with chronic thromboembolic pulmonary hypertension (CTEPH) with heart myxoma and thrombophilia of mixed origin, who underwent surgical treatment.Materials and methods. Patient Z., 24 years old, was admitted to the cardiology department with cough with sputum production that occurs during physical activity, including streaks of blood, shortness of breath with slight physical exertion, legs and feets edema, weakness and dizziness. The examination was carried out: electrocardiography; multislice computed tomography pulmonary angiography; echocardiography (EchoCG); transesophageal EchoCG; magnetic resonance imaging of the heart with contrast; screening for coagulopathy.Results. Based on clinical data, medical history, laboratory, instrumental diagnostic, we have put the diagnosis: Myxoma of the right atrium. Patent foramen ovale. Thrombophilia of mixed origin: hereditary – heterozygous mutation of the prothrombin gene (factor 2), acquired – hyperhomocysteinemia. Postthrombotic deep vein disease of the left lower limb. Recurrent pulmonary embolism (last relapse dated October 19, 2022). CTEPH functional class III (World Health Organization), moderate risk. Congestive heart failure with reduced right ventricular ejection fraction, functional class III (by the New York Heart Association). Relative tricuspid valve regurgitation grade 3. The patient underwent surgery: thromboendarterectomy from the right pulmonary artery under conditions of circulatory arrest and deep hypothermia, removal of a right atrium myxoma under conditions of artificial circulation and blood cold cardioplegia: tricuspid valve plasty according to De Vega. After surgery patient’s condition was significantly improved.Conclusion. The features of diagnosis and treatment of a patient suffering from CTEPH and cardiac myxoma are outlined. Surgery: Pulmonary thrombectomy and cardiac myxoma removal may improve the patient’s condition with CTEPH and left atrial myxoma.

Pulmonary vascular stenosis scoring in fibrosing mediastinitis.

This study aims to develop a scoring system for evaluating the degree of pulmonary vascular stenosis in fibrosing mediastinitis (FM). A retrospective single-centre study was conducted on 56 patients with FM in China between April 2014 and August 2021. The involvement of pulmonary vessels in patients with FM was assessed using dual-phase computed tomography pulmonary angiography, and we found that 85.7% of the patients had both pulmonary artery (PA) and vein (PV) involvement. PA involvement was mainly located proximal to both the upper PA and the bilateral basal trunk levels in the lower lungs. The involvement of the superior PV was more common than that of the inferior PV, and the right inferior PV was the least involved. Most of these lesions exhibited moderate or severe stenosis. Additionally, a scoring system for evaluating the degree of pulmonary vascular stenosis was developed. A correlation analysis revealed a negative correlation between the final pulmonary vascular score and the pulmonary arterial pressure, pulmonary vascular resistance, and maximum tricuspid regurgitation velocity. The calculated score of 17.1 was the best cut-off value for the diagnosis of mild and severe pulmonary hypertension (PH). We successfully developed a scoring system for pulmonary vascular stenosis that can be used to evaluate the severity of pulmonary vessel involvement and PH. This scoring system may be relevant in the future development of target-based strategies for percutaneous interventions.

Clinical prediction tool to identify children at risk of pulmonary embolism

IntroductionThe diagnosis of pediatric pulmonary embolism (PE) is often delayed due to non-specific symptoms, and clinical prediction tools designed for adults are unsuitable for children. This study aimed to create a PE predictive model and to evaluate the reported tools in the Thai pediatric population. Materials and methodsA multi-center retrospective study from 4 university hospitals included children ≤18 years of age undergoing computed tomography pulmonary angiogram from 2000 to 2020 with the suspicion of PE. Patients' clinical presentations and risk factors of venous thromboembolism (VTE) were compared between the PE-positive and PE-negative groups. Significant risk factors from univariate and multivariate logistic regression were included to create a clinical prediction tool. The performance of the model was demonstrated by sensitivity, specificity, area under the curve (AUC), Hosmer Lemeshow test, ratio of observed and expected outcomes and bootstrapping. ResultsOf the 104 patients included, 43 (41.3 %) were grouped as PE-positive and 61 (58.7 %) as PE-negative. Five parameters, including congenital heart disease/pulmonary surgery, known thrombophilia, previous VTE, nephrotic syndrome and chest pain showed significant differences between the two groups. Score ≥ 2 yielded a 74.4 % sensitivity and a 75.4 % specificity with an AUC of the model of 0.809. The model performance and validation results were within satisfactory ranges. ConclusionThe study created a clinical prediction tool indicating the likelihood of PE among Thai children. A score ≥2 was suggestive of PE.

Pregnancy-adapted YEARS Algorithm: A Retrospective Analysis.

Pulmonary embolism (PE) is an imperative diagnosis to make given its associated morbidity. There is no current consensus in the initial workup of pregnant patients suspected of a PE. Prospective studies have been conducted in Europe using a pregnancy-adapted YEARS algorithm, which showed safe reductions in computed tomography pulmonary angiography (CTPA) imaging in pregnant patients suspected of PE. Our objective in this study was 1)to measure the potential avoidance of CTPA use in pregnant patients if the pregnancy-adapted YEARS algorithm had been applied and 2)to serve as an external validation study of the use of this algorithm in the United States. This study was a single-system retrospective chart analysis. Criteria for inclusion in the cohort consisted of keywords: pregnant; older than 18; chief complaints of shortness of breath, chest pain, tachycardia, hemoptysis, deep vein thromboembolism (DVT), and D-dimer-from January 1, 2019- May 31,2022. We then analyzed this cohort retrospectively using the pregnancy-adapted YEARS algorithm, which includes clinical signs of a DVT, hemoptysis, and PE as the most likely diagnosis with a D-dimer assay. Patients within the cohort were then subdivided into two categories: aligned with the YEARS algorithm, or not aligned with the YEARS algorithm. Patients who did not receive a CTPA were analyzed for a subsequent diagnosis of a PE or DVT within 30 days. A total of 74 pregnant patients were included in this study. There was a PE prevalence of 2.7% (two patients). Of the 36 patients who did not require imaging by the algorithm, seven CTPA were performed. Of the patients who did not receive an initial CTPA, zero were diagnosed with PE or DVT within a 30-day follow-up. In total, 85.1% of all the patients in this study were treated in concordance with the pregnancy-adapted YEARS algorithm. The use of the pregnancy-adapted YEARS algorithm could have resulted in decreased utilization of CTPA in the workup of PE in pregnant patients, and the algorithm showed similar reductions compared to prospective studies done in Europe. The pregnancy-adapted YEARS algorithm was also shown to be similar to the clinical rationale used by clinicians in the evaluation of pregnant patients, which indicates its potential for widespread acceptance into clinical practice.

Deep learning in computed tomography pulmonary angiography imaging: A dual-pronged approach for pulmonary embolism detection

The increasing reliance on Computed Tomography Pulmonary Angiography (CTPA) for Pulmonary Embolism (PE) diagnosis presents challenges and a pressing need for improved diagnostic solutions. The primary objective of this study is to leverage deep learning techniques to enhance the Computer Assisted Diagnosis (CAD) of PE. With this aim, we propose a classifier-guided detection approach that effectively leverages the classifier’s probabilistic inference to direct the detection predictions, marking a novel contribution in the domain of automated PE diagnosis. Our classification system includes an Attention-Guided Convolutional Neural Network (AG-CNN) that uses local context by employing an attention mechanism. This approach emulates a human expert's attention by looking at both global appearances and local lesion regions before making a decision. The classifier demonstrates robust performance on the FUMPE dataset, achieving an AUROC of 0.927, sensitivity of 0.862, specificity of 0.879, and an F1-score of 0.805 with the Inception-v3 backbone architecture. Moreover, AG-CNN outperforms the baseline DenseNet-121 model, achieving an 8.1% AUROC gain. While previous research has mostly focused on finding PE in the main arteries, our use of cutting-edge object detection models and ensembling techniques greatly improves the accuracy of detecting small embolisms in the peripheral arteries. Finally, our proposed classifier-guided detection approach further refines the detection metrics, contributing new state-of-the-art to the community: mAP50, sensitivity, and F1-score of 0.846, 0.901, and 0.779, respectively, outperforming the former benchmark with a significant 3.7% improvement in mAP50. Our research aims to elevate PE patient care by integrating AI solutions into clinical workflows, highlighting the potential of human-AI collaboration in medical diagnostics.

Case Report: The importance of initial assessment in acute pulmonary embolism

Background: Pulmonary embolism (PE) remains the third most frequent cardiovascular disease worldwide and is associated with high mortality rates. We presented a case of PE with a history of tibial surgery and showed the role of Computed Tomography Pulmonary Angiography (CTPA) in early diagnosis and management of PE. Case presentation: A 23-year-old man was referred to our hospital with sudden dyspnea followed by sharp chest pain, haemoptysis, pre-syncope, diaphoresis, and weaknesses. He had a history of tibial surgery and immobilization one month before admission. His vital sign was unstable, with blood pressure of 110/60 mmHg (supported by Norepinefrin 0.5 mcg/kg/minutes), heart rate of 120 beats/minute, respiratory rate of 24 times/minute, and oxygen saturation of 99% (oxygen mask 6 lpm). An electrocardiogram showed sinus tachycardia with McGinn-White sign. A chest X-ray showed Palla sign. An echocardiogram showed reduced right ventricular systolic function with McConneal sign. CTPA was performed due to the moderate-high risk PE with the presence of hyperattenuating and partial filling defect. Streptokinase was then administered, followed by adequate anticoagulation using rivaroxaban for three months. The clinical and CTPA evaluation showed a good result. Conclusions: Initial assessment using PE’s scoring system will help clinicians determine the needs of CTPA. CTPA has a sensitivity of 53-100% and a specificity of 83-100% for the diagnosis of PE. This makes CTPA mandatory in high-risk PE, thus speeding up the initial treatment, which correlates with clinical outcomes.

The diagnostic yield for computed tomography pulmonary angiography in patients with anticoagulation.

Patients who present to the emergency department (ED) for suspected pulmonary embolism (PE) are often on active oral anticoagulation (AC). However, the diagnostic yield of computed tomography pulmonary angiography (CTPA) in screening for PE in patients who present on AC has not been well characterized. We aim to investigate the diagnostic yield of CTPA in diagnosing PE depending on AC status. We reviewed and analyzed the electronic medical records of patients who underwent CTPA for PE at a university hospital ED from June 1, 2019, to March 25, 2022. Primary outcome was the incidence of PE on CTPA depending on baseline AC status and indication for AC. Of 2,846 patients, 242 were on AC for a history of venous thromboembolism (VTE), 210 were on AC for other indications, and 2,394 were not on AC. The incidence of PE on CTPA was significantly lower in patients on AC for other indications (5.7%) when compared to patients on AC for prior VTE (24.3%) and patients not on AC at presentation (9.8%) (P<0.001). In multivariable analysis among the whole cohort, AC was associated with a positive CTPA (odds ratio [OR] 0.26, 95% confidence interval [CI]: 0.15-0.45, P<0.001). The incidence of PE among patients undergoing CTPA in the ED is lower in patients previously on AC for indications other than VTE when compared to those not on AC or those on AC for history of VTE. AC status and indication for AC may affect pre-test probability of a positive CTPA, and AC status therefore warrants consideration as part of future diagnostic algorithms among patients with suspected PE.

Trends in the utilization of computed tomography chest for acute pulmonary embolism in the emergency department and the yield in treatment

Background: Acute pulmonary embolism (PE) is a life-threatening condition with high mortality rates. Prompt and accurate diagnosis is crucial to prevent morbidity and mortality. Overutilizing computed tomography pulmonary angiography (CTPA) in low-risk patients can lead to unnecessary health-care costs and radiation exposure. Proper pretest probability assessment is recommended to guide the use of CTPA. Aim: This study aimed to evaluate the utilization of CTPA in the diagnosis of acute PE in the emergency department, with a focus on the application of pretest probability assessment (modified Wells score [MWS] and D-dimer). The primary objectives were to assess the extent of CTPA usage in low-risk patients, determine the effectiveness of D-dimer levels and the MWS in predicting PE, and identify areas for potential improvement in CTPA utilization to reduce unnecessary imaging and enhance patient care. In addition, the study aimed to evaluate the appropriateness of anticoagulant treatment in patients diagnosed with acute PE, particularly in cases of segmental/subsegmental PE. Settings and Design: A retrospective analysis was done on all suspected PE patients in the emergency room at our facility who underwent CTPA over 5 years. Patient demographic information, presenting complaints, physical examination findings, laboratory test results, and imaging findings were all included in the data collection. Materials and Methods: A retrospective review of 758 patient records at a tertiary hospital was conducted over 5 years. Data included demographics, presenting symptoms, test results, and imaging findings. D-dimer levels and the MWS were used for pretest probability evaluation. Anticoagulant treatment and appropriateness were also assessed. Statistical Analysis: Statistical analysis was carried out using RStudio (R version 4.3.0). Numerical variables were expressed as median (interquartile range), and frequencies and percentages were used to present categorical variables. A Fisher’s exact test was applied to assess the differences between patients who received anticoagulants and those who did not, as well as patients with PE statuses across D-dimer levels, Wells score categories, and receiving anticoagulants. A Kruskal–Wallis test explored the time to read reports between PE categories. P &lt;0.05 indicated statistical significance. Results: Among 758 patients, 18.8% had acute PE, with 6.2% being segmental/subsegmental PE. The majority of cases (79.8%) were negative for PE. A high rate of CTPA utilization was observed, especially in low-risk patients. Sixty-eight percent of low-risk patients had negative PE results. Among patients with acute PE, lobar PE (36.4%) and segmental/subsegmental PE (32.9%) were the most common locations. D-dimer and MWS were underutilized. Conclusions: By identifying low-risk patients who might not need CTPA, compliance with pretest probability evaluation using the MWS and D-dimer levels can help minimize unnecessary imaging and its associated risks. The results showed that efforts should be made to adhere to guidelines and recommendations, especially if the patients were categorized as low risk based on MWS or normal D-dimer levels. This will eventually improve patient outcomes and lower health-care costs.

Comparison of Radiation Doses of Computed Tomography Brain and Pulmonary Angiography with International Commission on Radiological Protection Guidelines: A Descriptive Study

Introduction: Computed Tomography Angiography (CTA) is useful for evaluating and diagnosing conditions related to blood vessels, such as aneurysms, stenosis (narrowing of vessels), vascular malformations, and blockages. It provides valuable information for planning and guiding interventions or surgeries. It is also important to measure patient doses during CTA operations to evaluate and optimise the technique and balance the benefits compared to radiation hazards. Aim: To calculate the CT Dose Index (CTDI), Dose Length Product (DLP), and effective dose for CT brain angiography and CT pulmonary angiography, and also to compare whether the measured values are within the International Commission on Radiological Protection (ICRP) recommended levels. Materials and Methods: A retrospective descriptive study was conducted in the Department of Radiodiagnosis at Yenepoya Medical College Hospital Mangaluru, Karnataka, India, from September 2022 to September 2023. A total of 52 data points were collected for CT brain and CT pulmonary angiography examinations, which were acquired before October 2022. Information on CTDI and DLP was collected, and the effective dose was calculated using the conversion factor. The values were then compared with the ICRP reference level. Descriptive statistics, mean, and standard deviation for continuous variables, and frequency and percentage for categorical variables were used. Results: There was a significantly lower value of CTDI, DLP, and effective dose for CT brain angiography and CT pulmonary angiography compared to the ICRP recommended reference levels. The mean CTDI and DLP for CT brain angiography were 111.56 mGy and 1153.31 mGy·cm, and the mean CTDI and DLP for CT pulmonary angiography were 24.56 mGy and 713.74 mGy·cm, respectively. The mean effective dose for CT brain and CT pulmonary angiography was 2.46 mSv and 9.94 mSv, respectively. Conclusion: The measured values were within the recommended values of ICRP regulations. It is recommended that CT brain angiography and CT pulmonary angiography examinations are safer for diagnostic purposes. Optimising scanning protocols, utilising low-dose techniques, and implementing dose monitoring and control are important clinical aspects. Compliance with the guidelines helps to enhance patient care and reduce the risk of radiation-related complications.

Usefulness of Delay Time Setting in Computed Tomography Pulmonary Angiography

During computed tomography pulmonary angiography (CTPA), a decrease in the CT value of the pulmonary artery may be observed due to poor contrast enhancement, even though the imaging is performed at the optimum timing while continuously injecting a contrast medium. This study focused on the increase in blood flow in the superior and inferior vena cava during inspiration that affects the decrease in the CT value of the pulmonary artery and investigated a radiography method in which a delay time was set after inspiration in clinical cases. A total of 50 patients who underwent CTPA for suspected pulmonary thromboembolism were included. Using the bolus tracking method, we monitored the pulmonary arteries before and after inspiration, and investigated the CT value changes. A decrease in the CT value of the pulmonary artery after inspiration was observed in approximately 30% of cases. By setting the delay time, the contrast enhancement effect before and after inspiration became equivalent. As a result of this study, avoiding a decrease in the CT value of the pulmonary artery is possible by setting a delay time after inspiration, which is considered useful during CTPA.

Deep Learning based Pulmonary Embolism Detection using Convolutional Feature Maps of CT Pulmonary Angiography Images

Pulmonary Embolism (PE) is a blood clot in the pulmonary arteries of the lungs. Currently, Computerized Tomography Pulmonary Angiography (CTPA) scans are used to diagnose this condition. However, to manually locate the presence of a PE in the scan is laborious. In this paper, the detection of PE and prediction of its features like location, Right Ventricle to Left Ventricle (RV/LV) ratio, and chronicity are automated. First, for the detection of the embolisms, image features from the RSNA Pulmonary Embolism CT (RSPECT) dataset - containing over 12,000 CTPA studies, are extracted by several pre-trained Convolutional Neural Networks (CNN) - AlexNet, Inception V3, ResNet-18, and ResNet-50. Then, various Machine Learning (ML) classifiers are trained on these features and their performances are compared. Second, for the prediction of labels, multi-label classification is performed by training these networks with Binary Cross Entropy Logits (BCE Logits) loss. The results showed that for the detection task, k-NN classifier trained on ResNet-50 features achieved the highest sensitivity of 0.98 with 1.7 false positives per scan and an AUROC score of 97.4%. This system also improved on the state-of-the-art sensitivity score by 0.0975 and AUROC score by 3.4%. For multi-label classification, ResNet-18 performed comparatively better with the best validation loss of 0.07 and weighted macro-average ROC AUC score of 0.61.

Clot ratio, new clot burden score with deep learning, correlates with the risk stratification of patients with acute pulmonary embolism.

Risk stratification for patients with acute pulmonary embolism (APE) is significantly important for treatment and prognosis evaluation. We aimed to develop a novel clot burden score on computed tomography pulmonary angiography (CTPA) based on deep learning (DL) algorithm for risk stratification of APE. The study retrospectively enrolled patients newly diagnosed with APE in China-Japan Friendship Hospital consecutively. We collected baseline data and CTPA parameters, and calculated four different clot burden scores, including Qanadli score, Mastora score, clot volume and clot ratio. The former two were calculated by two radiologists separately, while clot volume and clot ratio were based on the DL algorithm. The area under the curve (AUC) of four clot burden scores were analyzed. Seventy patients were enrolled, including 17 in high-/intermediate-high risk and 53 in low-/intermediate-low risk. Clot burden was related to the risk stratification of APE. Among four clot burden scores, clot ratio had the highest AUC (0.719, 95% CI: 0.569-0.868) to predict patients with higher risk. In the patients with hemodynamically stable APE, only clot ratio presented statistical difference (P=0.046). Clot ratio is a new imaging marker of clot burden which correlates with the risk stratification of patients with APE. Higher clot ratio may indicate higher risk and acute right ventricular dysfunction in patients with hemodynamically stable status.

Predictive Value of Pulmonary Artery Distensibility for Short-Term Adverse Clinical Outcomes in Patients with Acute Pulmonary Embolism.

We aimed to explore the relationship between pulmonary artery distensibility obtained from computed tomography pulmonary angiography (CTPA) and short-term adverse clinical outcomes in patients with acute pulmonary embolism (APE). We included patients who underwent retrospective electrocardiogram-gated CTPA and were subsequently diagnosed with APE. Patients were categorized into good and poor outcome groups based on short-term clinical outcomes. Pulmonary artery distensibility (AD), right ventricle/left ventricle (RV/LV) ratio, and pulmonary artery obstruction index (PAOI) were measured, and the receiver operating characteristic curves were constructed. Sixty-four patients with APE (good outcome, 46; poor outcome, 18) were enrolled. AD, RV/LV ratio, and PAOI differed significantly between groups (P < 0.05). Pulmonary artery AD in the good outcome group was greater than that in the poor outcome group (P < 0.001). The poor outcome group exhibited a higher RV/LV ratio and PAOI than the good outcome group (P < 0.05). AD and PAOI were independent predictors of adverse clinical outcomes. Areas under the curve for AD and PAOI were 0.860 (95% confidence interval [CI]: 0.750-0.934) and 0.675 (95%CI: 0.546-0.786), and the combined curve of the AD and RV/LV ratio was 0.906 (95%CI: 0.806-0.965). The calibration curve showed a combined curve superior to the other curves. The decision curve showed high clinical application value of the combined curve. Retrospective electrocardiogram-gated CTPA-derived AD could serve as an indicator for predicting short-term adverse clinical outcomes in APE. Combining AD and PAOI has a high predictive value for short-term adverse clinical outcomes.