Influencing factors on the time to CT in suspected pulmonary embolism: an explorative investigation.

Pulmonary embolism is a potentially fatal condition with increased mortality if anticoagulation is delayed. This study aimed to find influencing factors on the duration from requesting a computed tomography (CT) pulmonary angiography (CTPA) to performing a CTPA in suspected acute pulmonary embolism. In 1849 cases, automatically generated time data were extracted from the radiological information system. The impact of the distance to the scanner, case-related features (sector of patient care, triage), and workload (demand for CTs, performed CTs, available staff, hospital occupancy) were investigated retrospectively using multiple regression. The time to CTPA was shorter in cases from the emergency room (ER) than in inpatients and outpatients at distances below 160 m and 240 m, respectively. While requests from the ER were also performed faster than cases from regular wards (< 180 m), no difference was found between the ER and intensive care units. Compared to "not urgent" cases, the workflow was shorter in "urgent" (- 17%) and "life-threatening" (- 67%) situations. The process was prolonged with increasing demand (+ 5%/10 CTs). The presented analysis identified relevant in-hospital influences on the CTPA workflow, including the distance to the CT together with the sector of patient care, the case triage, and the demand for imaging.

Comprehensive analysis of splenic artery variations using computed tomography angiography: development of the IPALGEA classification system.

BACKGROUND: The splenic artery, an essential component of abdominal vascular anatomy, exhibits significant variations with clinical implications in surgical and radiological procedures. The lack of a standardized classification system for these variations hinders comparative studies and surgical planning. This study introduces the IPALGEA classification system, based on computed tomography angiography (CTA) findings, to address this gap. METHODS: A retrospective analysis was conducted on 302 patients who underwent CTA at a tertiary university hospital between August 2021 and January 2022. The study focused on the evaluation of splenic artery variations, including the origin, course, terminal branching patterns, and the relationship between the inferior polar artery and the left gastroepiploic artery. The IPALGEA classification was developed to standardize the reporting of these variations. RESULTS: The study highlighted a significant prevalence of splenic artery variations, with the most common pattern being a superior course relative to the pancreas. The IPALGEA classification effectively categorized these variations, emphasizing the relationship between the inferior polar artery and the left gastroepiploic artery. The findings revealed that the bifurcation distance of the celiac trunk varied significantly between genders and that the presence of an inferior polar artery correlated with a shorter hilus distance. CONCLUSION: The IPALGEA classification offers a comprehensive and standardized approach to categorize splenic artery variations. This system enhances our understanding of abdominal vascular anatomy and has significant implications for surgical and radiological procedures, potentially reducing surgical complications and improving patient outcomes.

Successful surgical attenuation of portosystemic shunt in a dog with imaging-diagnosed portal vein aplasia.

An 8-month-old female Maltese dog was referred for examination with a history of circling, dullness, and drooling. Serum biochemical analysis revealed hyperammonemia, with microhepatica observed on radiography. Computed tomography angiography revealed a portosystemic shunt originating from the right gastric vein and inserting into the prehepatic caudal vena cava. Portal blood flow to the liver was not observed. Based on computed tomography angiography, the dog was tentatively diagnosed with portosystemic shunt with portal vein aplasia. An exploratory laparotomy was done to obtain a definitive diagnosis. The dog had no subjective clinical signs of portal hypertension during a temporary occlusion test of the portosystemic shunt. A thin-film band was placed around the portosystemic shunt to achieve partial attenuation. There was no evidence of hepatic encephalopathy in the long term after surgery, and the dog's liver volume increased over time. Computed tomography angiography at 6 mo after surgery identified well-visualized intrahepatic portal branches. Key clinical message: We inferred that a direct occlusion test is a reliable diagnostic technique that overcomes the limitations of diagnostic imaging methods, including computed tomography angiography, and is a good technique for determining whether surgical attenuation is possible in dogs with suspected portal vein aplasia.

Atténuation chirurgicale réussie d'un shunt porto-systémique chez un chien avec une aplasie de la veine porte diagnostiquée par imagerie. Une femelle bichon maltais âgée de 8 mois a été référée pour examen avec une histoire de tournis, apathie et salivation excessive. L'analyse biochimique du sérum a révélé une hyperammionémie, avec un petit foie observé lors des radiographies. Une angiographie par tomodensitométrie a révélé un shunt porto-systémique prenant son origine de la veine gastrique droite et s'insérant dans la veine cave caudale pré-hépatique. Le flot sanguin porte au foie n'était pas observé. Sur la base de l'angiographie par tomodensitométrie, un diagnostic présumé de shunt porto-systémique avec aplasie de la veine porte a été émis. Une laparotomie exploratoire a été effectuée afin d'obtenir un diagnostic définitif. Le chien ne présentait pas de signe clinique subjectif d'hypertension portale durant un test d'occlusion temporaire du shunt porto-systémique. Une bande de film mince a été placée autour du shunt porto-systémique pour causer une réduction partielle. Il n'y avait aucune évidence d'encéphalopathie hépatique à long terme après la chirurgie, et le volume du foie du chien a augmenté dans le temps. Une angiographie par tomodensitométrie effectuée 6 mo après la chirurgie a permis de bien visualiser des branches portes intra-hépatiques.Message clinique clé :Nous avons déduit qu'un test d'occlusion est une technique diagnostique fiable qui surpasse les limites des méthodes d'imagerie diagnostique, incluant l'angiographie par tomodensitométrie, et est une bonne technique pour déterminer si une réduction chirurgicale est possible chez des chiens chez qui on soupçonne une aplasie de la veine porte.(Traduit par Dr Serge Messier).

External validation of the RSNA 2020 pulmonary embolism detection challenge winning deep learning algorithm.

PURPOSE: To evaluate the diagnostic performance and generalizability of the winning DL algorithm of the RSNA 2020 PE detection challenge to a local population using CTPA data from two hospitals. MATERIALS AND METHODS: Consecutive CTPA images from patients referred for suspected PE were retrospectively analysed. The winning RSNA 2020 DL algorithm was retrained on the RSNA-STR Pulmonary Embolism CT (RSPECT) dataset. The algorithm was tested in hospital A on multidetector CT (MDCT) images of 238 patients and in hospital B on spectral detector CT (SDCT) and virtual monochromatic images (VMI) of 114 patients. The output of the DL algorithm was compared with a reference standard, which included a consensus reading by at least two experienced cardiothoracic radiologists for both hospitals. Areas under the receiver operating characteristic curve (AUCs) were calculated. Sensitivity and specificity were determined using the maximum Youden index. RESULTS: According to the reference standard, PE was present in 73 patients (30.7%) in hospital A and 33 patients (29.0%) in hospital B. For the DL algorithm the AUC was 0.96 (95% CI 0.92-0.98) in hospital A, 0.89 (95% CI 0.81-0.94) for conventional reconstruction in hospital B and 0.87 (95% CI 0.80-0.93) for VMI. CONCLUSION: The RSNA 2020 pulmonary embolism detection on CTPA challenge winning DL algorithm, retrained on the RSPECT dataset, showed high diagnostic accuracy on MDCT images. A somewhat lower performance was observed on SDCT images, which suggest additional training on novel CT technology may improve generalizability of this DL algorithm.

Incidental Ring-hyperenhancing Liver Micronodules at CT Hepatic Arteriography-guided Percutaneous Thermal Ablation of Colorectal Liver Metastases.

CT during hepatic arteriography (CTHA) is a highly sensitive imaging method for detecting colorectal liver metastases (CLMs), which supports its use during percutaneous thermal liver ablation. In contrast to its high sensitivity, its specificity for incidental small CLMs not detected at preablation cross-sectional imaging is believed to be low given the absence of specific imaging signatures and the common presence of pseudolesions. In this retrospective study of 22 patients (mean age, 55 years ± 10.6 [SD]; 63.6% male, 36.4% female) with CLMs undergoing CTHA-guided microwave percutaneous thermal ablation between November 2017 and October 2022, the authors provided a definition of incidental ring-hyperenhancing liver micronodules (RHLMs) and investigated whether there is a correlation of RHLMs with histologic analysis or intrahepatic tumor progression at imaging follow-up after applying a biomechanical deformable image registration method. The analysis revealed 25 incidental RHLMs in 41.7% (10 of 24) of the CTHA images from the respective guided ablation sessions. Of those, four RHLMs were ablated. Among the remaining 21 RHLMs, 71.4% (15 of 21) were confirmed to be CLM with either histology (n = 3) or imaging follow-up (n = 12). The remaining 28.6% (six of 21) of RHLMs were not observed at follow-up imaging. This suggests that RHLMs at CTHA may be an early indicator of incidental small CLMs. Keywords: Colorectal Neoplasms, Liver, Angiography, CT, Incidental Findings, Ablation Supplemental material is available for this article. © RSNA, 2024.

A deep learning-based algorithm improves radiology residents' diagnoses of acute pulmonary embolism on CT pulmonary angiograms.

PURPOSE: To compare radiology residents' diagnostic performances to detect pulmonary emboli (PEs) on CT pulmonary angiographies (CTPAs) with deep-learning (DL)-based algorithm support and without. METHODS: Fully anonymized CTPAs (n = 207) of patients suspected of having acute PE served as input for PE detection using a previously trained and validated DL-based algorithm. Three residents in their first three years of training, blinded to the index report and clinical history, read the CTPAs first without, and 2 months later with the help of artificial intelligence (AI) output, to diagnose PE as present, absent or indeterminate. We evaluated concordances and discordances with the consensus-reading results of two experts in chest imaging. RESULTS: Because the AI algorithm failed to analyze 11 CTPAs, 196 CTPAs were analyzed; 31 (15.8 %) were PE-positive. Good-classification performance was higher for residents with AI-algorithm support than without (AUROCs: 0.958 [95 % CI: 0.921-0.979] vs. 0.894 [95 % CI: 0.850-0.931], p < 0.001, respectively). The main finding was the increased sensitivity of residents' diagnoses using the AI algorithm (92.5 % vs. 81.7 %, respectively). Concordance between residents (kappa: 0.77 [95 % CI: 0.76-0.78]; p < 0.001) improved with AI-algorithm use (kappa: 0.88 [95 % CI: 0.87-0.89]; p < 0.001). CONCLUSION: The AI algorithm we used improved between-resident agreements to interpret CTPAs for suspected PE and, hence, their diagnostic performances.

Study of ischemic progression in different intestinal tissue layers during acute intestinal ischemia using swept-source optical coherence tomography angiography.

In acute intestinal ischemia, the progression of ischemia varies across different layers of intestinal tissue. We established a mouse model and used swept-source optical coherence tomography (OCT) to observe the intestinal ischemic process longitudinally in different tissue layers. Employing a method that combines asymmetric gradient filtering with adaptive weighting, we eliminated the vessel trailing phenomenon in OCT angiograms, reducing the confounding effects of superficial vessels on the imaging of deeper vasculature. We quantitatively assessed changes in vascular perfusion density (VPD), vessel length, and vessel average diameter across various intestinal layers. Our results showed a significant reduction in VPD in all layers during ischemia. The mucosa layer experienced the most significant impact, primarily due to disrupted capillary blood flow, followed by the submucosa layer, where vascular constriction or decreased velocity was the primary factor.

Enhancing diagnostic precision for acute chest syndrome in sickle cell disease: insights from dual-energy CT lung perfusion mapping.

PURPOSE: Acute chest syndrome (ACS) is secondary to occlusion of the pulmonary vasculature and a potentially life-threatening complication of sickle cell disease (SCD). Dual-energy CT (DECT) iodine perfusion map reconstructions can provide a method to visualize and quantify the extent of pulmonary microthrombi. METHODS: A total of 102 patients with sickle cell disease who underwent DECT CTPA with perfusion were retrospectively identified. The presence or absence of airspace opacities, segmental perfusion defects, and acute or chronic pulmonary emboli was noted. The number of segmental perfusion defects between patients with and without acute chest syndrome was compared. Sub-analyses were performed to investigate robustness. RESULTS: Of the 102 patients, 68 were clinically determined to not have ACS and 34 were determined to have ACS by clinical criteria. Of the patients with ACS, 82.4% were found to have perfusion defects with a median of 2 perfusion defects per patient. The presence of any or new perfusion defects was significantly associated with the diagnosis of ACS (P = 0.005 and < 0.001, respectively). Excluding patients with pulmonary embolism, 79% of patients with ACS had old or new perfusion defects, and the specificity for new perfusion defects was 87%, higher than consolidation/ground glass opacities (80%). CONCLUSION: DECT iodine map has the capability to depict microthrombi as perfusion defects. The presence of segmental perfusion defects on dual-energy CT maps was found to be associated with ACS with potential for improved specificity and reclassification.

Improved image quality in CT pulmonary angiography using deep learning-based image reconstruction.

We investigated the effect of deep learning-based image reconstruction (DLIR) compared to iterative reconstruction on image quality in CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE). For 220 patients with suspected PE, CTPA studies were reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASiR-V 30%, 60% and 90%) and DLIR (low, medium and high strength). Contrast-to-noise ratio (CNR) served as the primary parameter of objective image quality. Subgroup analyses were performed for normal weight, overweight and obese individuals. For patients with confirmed PE (n = 40), we further measured PE-specific CNR. Subjective image quality was assessed independently by two experienced radiologists. CNR was lowest for FBP and enhanced with increasing levels of ASiR-V and, even more with increasing strength of DLIR. High strength DLIR resulted in an additional improvement in CNR by 29-67% compared to ASiR-V 90% (p < 0.05). PE-specific CNR increased by 75% compared to ASiR-V 90% (p < 0.05). Subjective image quality was significantly higher for medium and high strength DLIR compared to all other image reconstructions (p < 0.05). In CT pulmonary angiography, DLIR significantly outperforms iterative reconstruction for increasing objective and subjective image quality. This may allow for further reductions in radiation exposure in suspected PE.

Presurgical imaging of the subscapular artery with three-dimensional-computed tomography angiography: Application to harvesting subscapular system free-flaps.

A subscapular system free-flap is extremely useful for maxillofacial reconstruction since it facilitates the simultaneous harvesting of multiple flaps using one subscapular artery (SSA) alone. However, cases of aberrations in the SSAs have been reported. Therefore, the morphology of SSA needs to be confirmed preoperatively before harvesting the flaps. Recent developments in imaging, such as three-dimensional (3D) computed tomography angiography (3D CTA), facilitate obtain high-quality images of blood vessel images. Therefore, we examined the utility of 3D CTA in navigating the course of the SSA before harvesting subscapular system free-flaps. We examined the morphology and aberrations of the SSA using 39 sides of the 3D CTA data and 22 sides of Japanese cadavers. SSAs can be classified into types S, I, P, and A. Type S SSAs are significantly long (mean length = 44.8 mm). Types I and P SSAs have short mean lengths, measuring ≤2 cm in approximately 50% of cases. In type A, the SSA is absent. The frequency of types S, I, P, and A SSAs were 28.2%, 7.7%, 51.3%, and 12.8%, respectively. Type S can be advantageous for harvesting the SSA in subscapular system free-flaps, because it is significantly longer. In contrast, types I and P might be dangerous because their mean lengths are shorter. In type A, caution is needed not to injure the axillary artery because the SSA is absent. When surgeons need to harvest the SSA, presurgical 3D CTA is recommended.

Minimizing Contrast Media Dose in CT Pulmonary Angiography with Clinical Photon Counting Using High Pitch Technique.

RATIONALE AND OBJECTIVES: To evaluate the potential to reduce the amount of iodinated contrast media (CM) for computer tomographic pulmonary angiography (CTPA) with a novel photon-counting-detector CT (PCCT). MATERIALS AND METHODS: Overall, 105 patients referred for CTPA were retrospectively included in this study. CTPA was performed using bolus tracking and high-pitch dual-source scanning (FLASH mode) on a novel PCCT (Naeotom Alpha, Siemens Healthineers). CM (Accupaque 300, GE Healthcare) dose was lowered stepwise following the introduction of the new CT scanner. Thus, patients could be divided into 3 groups as follows: group 1, n = 29, 35 ml of CM; group 2, n = 62, 45 ml of CM and group 3, n = 14, 60 ml of CM. Four readers independently assessed the image quality (Likert-scale 1-5) and adequate assessment of the segmental pulmonary arteries. Additionally, the pulmonary arterial contrast opacification was measured. RESULTS: The subjective image quality was rated highest in group 1 with 4.6 compared to 4.5 (group 2) and 4.1 (group 3) with a significant difference between groups 1 and 3 (p < 0.001) and between groups 2 and 3 (p = 0.003). In all groups, almost all segmental pulmonary arteries could be assessed adequately without significant differences (18.5 vs. 18.7 vs. 18.4). Mean attenuation in the pulmonary trunk did not differ significantly between groups 321 ± 92 HU versus 345 ± 93 HU versus 347 ± 88 HU (p = 0.69). CONCLUSION: Significant CM dose reduction is possible without a reduction in image quality. PCCT enables diagnostic CTPA with 35 ml of CM.

Bronchial embolisation for infected pulmonary artery pseudoaneurysms causing haemoptysis.

AIM: To report the authors' experience of bronchial artery embolisation (BAE) in a series of patients to control haemoptysis associated with infected pulmonary artery pseudoaneurysms (PAPs). MATERIALS AND METHODS: All patients who underwent BAE based on computed tomography angiography (CTA) findings indicative of haemoptysis between February 2019 and September 2022 at Xiangyang Central Hospital were identified. Charts of patients with haemoptysis and infectious PAPs were reviewed retrospectively. Data were collected data on age, sex, underlying pathology, source pulmonary artery of the PAP, association with cavitary lesions or consolidation, systemic angiography findings, technical and clinical success, and follow-up. RESULTS: Seventeen PAPs were treated in 16 patients, with a mean age of 60.3 years (range: 37-82 years). The most common underlying cause was tuberculosis (15/16, 93.8%). Imaging by CTA did not identify the source pulmonary artery for 15 (88.2%) PAPs; all were associated with cavitary lesions or consolidation. All PAPs were visualised on systemic angiography. The technical and clinical success rates were both 87.5%. Two patients who experienced a recurrence of haemoptysis during follow-up underwent repeat CTA, which confirmed the elimination of the previous PAP. CONCLUSION: BAE may be a valuable technique to control haemoptysis associated with infectious PAPs that are visualised on systemic angiography. A possible contributing factor is PAPs arising from very small pulmonary arteries.

A pseudo-dilemma: Are we over-diagnosing and over-treating traumatic splenic intraparenchymal pseudoaneurysms?

BACKGROUND: Splenic embolization for traumatic vascular abnormalities in stable patients is a common practice. We hypothesize that modern contrast-enhanced computed tomography (CT) over diagnoses posttraumatic splenic vascular lesions, such as intraparenchymal pseudoaneurysms (PSA) that may not require embolization. METHODS: We reviewed the experience at our high-volume center with endovascular management of blunt splenic injuries from January 2016 to December 2021. Multidisciplinary review was used to compared initial CT findings with subsequent angiography, analyzing management and outcomes of identified vascular lesions. RESULTS: Of 853 splenic injuries managed overall during the study period, 255 (29.9%) underwent angiography of the spleen at any point during hospitalization. Vascular lesions were identified on 58% of initial CTs; extravasation (12.2%) and PSA (51.0%). Angiography was performed a mean of 22 hours after admission, with 38% done within 6 hours. Embolization was performed for 90.5% (231) of patients. Among the 130 patients with PSA on initial CT, 36 (27.7%) had no visible lesion on subsequent angiogram. From the 125 individuals who did not have a PSA identified on their initial CT, 67 (54%) had a PSA seen on subsequent angiography. On postembolization CT at 48 hours to 72 hours, persistently perfused splenic PSAs were seen in 41.0% (48/117) of those with and 22.2% (2/9) without embolization. Only one of 24 (4.1%) patients with PSA on angiography observed without embolization required delayed splenectomy, whereas 6.9% (16/231) in the embolized group had splenectomy at a mean of 5.5 ± 4 days after admission. CONCLUSION: There is a high rate of discordance between CT and angiographic identification of splenic PSAs. Even when identified at angiogram and embolized, close to half will remain perfused on follow-up imaging. These findings question the use of routine angioembolization for all splenic PSAs. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.

High-pitch CT pulmonary angiography (CTPA) with ultra-low contrast medium volume for the detection of pulmonary embolism: a comparison with standard CTPA.

OBJECTIVE: To investigate the feasibility and image quality of high-pitch CT pulmonary angiography (CTPA) with reduced iodine volume in normal weight patients. METHODS: In total, 81 normal weight patients undergoing CTPA for suspected pulmonary arterial embolism were retrospectively included: 41 in high-pitch mode with 20 mL of contrast medium (CM); and 40 with normal pitch and 50 mL of CM. Subjective image quality was assessed and rated on a 3-point scale. For objective image quality, attenuation and noise values were measured in all pulmonary arteries from the trunk to segmental level. Contrast-to-noise ratio (CNR) was calculated. Radiation dose estimations were recorded. RESULTS: There were no statistically significant differences in patient and scan demographics between high-pitch and standard CTPA. Subjective image quality was rated good to excellent in over 90% of all exams with no significant group differences (p = 0.32). Median contrast opacification was lower in high-pitch CTPA (283.18 [216.06-368.67] HU, 386.81 [320.57-526.12] HU; p = 0.0001). CNR reached a minimum of eight in all segmented arteries, but was lower in high-pitch CTPA (8.79 [5.82-12.42], 11.01 [9.19-17.90]; p = 0.005). Median effective dose of high-pitch CTPA was lower (1.04 [0.72-1.27] mSv/mGy·cm; 1.49 [1.07-2.05] mSv/mGy·cm; p < 0.0001). CONCLUSION: High-pitch CTPA using ultra-low contrast volume (20 mL) rendered diagnostic images for the detection of pulmonary arterial embolism in most instances. Compared to standard CTPA, the high-pitch CTPA exams with drastically reduced contrast medium volume had also concomitantly reduced radiation exposure. However, objective image quality of high-pitch CTPA was worse, though likely still within acceptable limits for confident diagnosis. CLINICAL RELEVANCE: This study provides valuable insights on the performance of a high-pitch dual-source CTPA protocol, offering potential benefits in reducing contrast medium and radiation dose while maintaining sufficient image quality for accurate diagnosis in patients suspected of pulmonary embolism. KEY POINTS: • High-pitch CT pulmonary angiography (CTPA) with ultra-low volume of contrast medium and reduced radiation dose renders diagnostic examinations with comparable subjective image quality to standard CTPA in most patients. • Objective image quality of high-pitch CTPA is reduced compared to standard CTPA, but contrast opacification and contrast-to-noise ratio remain above diagnostic thresholds. • Challenges of high-pitch CTPA may potentially be encountered in patients with severe heart failure or when performing a Valsalva maneuver during the examination.

Imaging peritoneal blood vessels through optical coherence tomography angiography for laparoscopic surgery.

Laparoscopic surgery presents challenges in identifying blood vessels due to lack of tactile feedback. The image-guided laparoscopic surgical tool (IGLaST) integrated with optical coherence tomography (OCT) has potential for in vivo blood vessel imaging; however, distinguishing vessels from surrounding tissue remains a challenge. In this study, we propose utilizing an inter-A-line intensity differentiation-based OCT angiography (OCTA) to improve visualization of blood vessels. By evaluating a tissue phantom with varying flow speeds, we optimized the system's blood flow imaging capabilities in terms of minimum detectable flow and contrast-to-noise ratio. In vivo experiments on rat and porcine models, successfully visualized previously unidentified blood vessels and concealed blood flows beneath the 1 mm depth peritoneum. Qualitative comparison of various OCTA algorithms indicated that the intensity differentiation-based algorithm performed best for our application. We believe that implementing IGLaST with OCTA can enhance surgical outcomes and reduce procedure time in laparoscopic surgeries.

Even non-expert radiologists report chronic thromboembolic pulmonary hypertension (CTEPH) on CT pulmonary angiography with high sensitivity and almost perfect agreement.

OBJECTIVES: To assess the diagnostic performance and interobserver agreement of CT pulmonary angiography (CTPA) in the detection of chronic thromboembolic pulmonary hypertension (CTEPH) and its features among radiologists of different levels of experience. MATERIALS AND METHODS: In this retrospective, single-center, single-blinded study, three radiologists with different levels of experience in CT imaging (R1:15 years, R2:6 years, and R3:3 years) evaluated CTPA of 51 patients ultimately diagnosed with CTEPH (European Society of Cardiology guidelines) and 49 patients without CTEPH in random order to assess the presence of CTEPH, its features in the pulmonary artery tree, proximal level of involvement, bronchial artery hypertrophy, mosaic perfusion, and right heart overload. RESULTS: CTPAs of 51 patients with CTEPH (median age, 66 years (IQR 56-72), 28 men) and 49 patients without CTEPH (median age, 65 years (IQR 50-74), 25 men) were evaluated. The sensitivity and specificity for the detection of CTEPH was 100% (all radiologists) and 100% (R1), 96% (R2), and 96% (R3) with almost perfect agreement (κ = 0.95). The sensitivity and specificity for detecting CTEPH by mosaic perfusion would be 89% (95%CI 83-93%) and 81% (74-87%). The level of pulmonary artery involvement was reported with moderate agreement (κ = 0.54, 95%CI 0.40-0.65). Substantial agreement was found in the evaluation of mosaic attenuation (κ = 0.75, 95%CI 0.64-0.84), right heart overload (κ = 0.68, 95%CI 0.56-0.79), and bronchial artery hypertrophy (0.71, 95%CI 0.59-0.82) which were the best predictors of CTEPH (p < 0.0001). CONCLUSIONS: CTPA has high sensitivity and specificity in detecting CTEPH and almost perfect agreement among radiologists of different levels of expertise. CLINICAL RELEVANCE: CT pulmonary angiography can be used as a first-line imaging modality in patients with suspected chronic thromboembolic pulmonary hypertension (CTEPH) even when interpreted by non-CTEPH experts. KEY POINTS: • CT pulmonary angiography has high sensitivity and specificity in detecting chronic thromboembolic pulmonary hypertension (CTEPH) and almost perfect interobserver agreement among radiologists of different levels of expertise. • Substantial agreement exists in the assessment of mosaic attenuation, right heart overload, and bronchial artery hypertrophy, which are the best predictors of CTEPH.

Perfusion Analysis Using High-Definition Indocyanine Green Angiography in Burn Comb Model.

Indocyanine green angiography (ICGA) has been widely employed for quantitative evaluation of the rat comb burn model, but the imaging equipment, imaging protocol, and fluorescence data interpretation of ICGA remain unsatisfactory. This study aims to provide better solutions for the application of ICGA in perfusion analysis. The rat comb burn model was established under a series of different comb contact durations, including 10, 20, 25, 30, 35, and 40 s. Indocyanine green angiography was used to analyze wound perfusion. In total, 16 rats were divided into ibuprofen and control groups for the burn model, and their perfusion was compared. A total of 16 identical models were divided into standard- and high-dose indocyanine green (ICG) groups, and ICGA was conducted to investigate the dynamic change in wound fluorescence. Escharectomy was performed under real-time fluorescence mapping and navigation. The results showed that a comb contact duration of 30 s was optimum for the burn model. Indocyanine green angiography could accurately evaluate the histologically determined depth of thermal injury and wound perfusion in the rat comb model. Digital subtraction of residual fluorescence was necessary for multiple comparisons of perfusion. Dynamic changes in fluorescence and necrotic tissues were observed more clearly by high-dose (0.5 mg/kg) ICG in angiography. In conclusion, perfusion analysis by ICGA can be used to assess the histologically determined depth of thermal injury and the impact of a specific treatment on wound perfusion. Indocyanine green angiography can help to identify necrotic tissue. The above findings and related imaging protocols lay the foundation for future research.

Hotspots of facial artery perforators and perforasomes for easier flap guidance: An anatomical study.

BACKGROUND: The facial artery perforator flap is a valuable alternative for reconstruction of small to medium defects in the central midface and provide pleasing cosmetic results, allowing reconstruction in a one-stage procedure. Since Doppler ultrasound is not applicable to distinguish perforator from source artery, anatomical studies are needed to identify perforator areas along the course of the facial artery. METHODS: Twenty facial arteries of 10 fresh anatomical head specimens were dissected. All perforators with an outer diameter of at least 0.50 mm were identified and injected with dye to color their respective vascular territories. Size and location of colored skin territories as well as the location of its perforators were documented and statistically analyzed. RESULTS: In total, 89 perforators were identified. The average number of perforators per facial artery was 4.45±1.15. The mean outer diameter of the perforator at the origin of the facial artery was 0,65±0.14 mm. The mean size of the colored skin territories was 577.57±488.81 mm2. Perforator diameters were significantly associated with the size of its resulting perforasomes. Furthermore, perforators mostly originated in two specific areas: 3.5 cm lateral and caudal and 4.5 cm lateral and 5.5 cm caudal of the anterior nasal spine. CONCLUSION: This study provides evidence of two predominant locations of emergence of facial artery perforators. Additionally, the significant correlation between perforator size and its appendant perforasomes as well as their location with reference to the anterior nasal spine as relevant osseous landmarks helps surgeons in decision making for flap design and surgery.

Improved small vessel visibility in diabetic foot arteriography using dual-energy CT.

AIM: To test the feasibility and performance of dual-energy computed tomography (DECT) in foot arteriography of diabetic patients, where contrast medium is largely reduced within the small vessels. MATERIALS AND METHODS: A total of 50 diabetic patients were enrolled prospectively, where DECT was acquired immediately after the CT angiography (CTA, group A) of the lower extremity. Two images were derived from the DECT data, one optimal virtual monochromatic image (VMI, group B) and one fusion image (group C), both of which were compared against the CTA image for visualising the foot arteries. The contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were evaluated. The arterial course and contrast were graded each using a five-point scale. The clarity of small vessel depiction was quantified by comparing the number of plantar metatarsal arteries found in the maximum intensity projection image. RESULTS: The median CNRs and SNRs obtained in group B were approximately 45% and 20% higher than those in groups A and C, respectively (p<0.05). Group B also received higher subjective scores on the posterior tibial artery and the foot arteries (all >3) than groups A and C. The number of visible branches of the plantar metatarsal arteries was found to be substantially higher (p<0.05) in group B (median=6) than in groups A (median=2) and C (median=4). CONCLUSION: DECT was found to be superior to conventional CTA in foot arteriography, and beyond the lower extremity, it might be a general favourable solution for imaging regions with small vessels and reduced contrast medium.

Dynamic Computed Tomography Angiography for capturing vessel wall motion: A phantom study for optimal image reconstruction.

BACKGROUND: Reliably capturing sub-millimeter vessel wall motion over time, using dynamic Computed Tomography Angiography (4D CTA), might provide insight in biomechanical properties of these vessels. This may improve diagnosis, prognosis, and treatment decision making in vascular pathologies. PURPOSE: The aim of this study is to determine the most suitable image reconstruction method for 4D CTA to accurately assess harmonic diameter changes of vessels. METHODS: An elastic tube (inner diameter 6 mm, wall thickness 2 mm) was exposed to sinusoidal pressure waves with a frequency of 70 beats-per-minute. Five flow amplitudes were set, resulting in increasing sinusoidal diameter changes of the elastic tube, measured during three simulated pulsation cycles, using ECG-gated 4D CTA on a 320-detector row CT system. Tomographic images were reconstructed using one of the following three reconstruction methods: hybrid iterative (Hybrid-IR), model-based iterative (MBIR) and deep-learning based (DLR) reconstruction. The three reconstruction methods where based on 180 degrees (half reconstruction mode) and 360 degrees (full reconstruction mode) raw data. The diameter change, captured by 4D CTA, was computed based on image registration. As a reference metric for diameter change measurement, a 9 MHz linear ultrasound transducer was used. The sum of relative absolute differences (SRAD) between the ultrasound and 4D CTA measurements was calculated for each reconstruction method. The standard deviation was computed across the three pulsation cycles. RESULTS: MBIR and DLR resulted in a decreased SRAD and standard deviation compared to Hybrid-IR. Full reconstruction mode resulted in a decreased SRAD and standard deviations, compared to half reconstruction mode. CONCLUSIONS: 4D CTA can capture a diameter change pattern comparable to the pattern captured by US. DLR and MBIR algorithms show more accurate results than Hybrid-IR. Reconstruction with DLR is >3 times faster, compared to reconstruction with MBIR. Full reconstruction mode is more accurate than half reconstruction mode.