Pulmonary Vascular Segments Research Articles

3D Visualization of Pulmonary Vessel Based on Low-Cost Segmentation and Fast Reconstruction

Real-time visual-aided navigation and path strategy for pneumonoconiosis and efficient 3D visualization of pulmonary vessels are of great research and clinical significance in the treatment of lung diseases. The complex structure of lung tissue limits the application of deep learning in pulmonary vascular visualization due to the lack of vascular labeling datasets. Also, the existing methods have large computational complexity and are low efficiency. This study proposes a method for high-quality 3D visualization of pulmonary vessels based on low-cost segmentation and fast reconstruction, consisting of three steps: 1) Pulmonary vessel feature extraction from lung CT images using self-supervised learning, 2) Segmentation of pulmonary sparse vessels in lung CT images using self-supervised transfer learning, and 3) 3D reconstruction of pulmonary vessels based on segmentation results of step (2) using interpolation. The accuracy of pulmonary vascular contour segmentation was improved from 91.31% using the sparse coding to 98.65% using our proposed method (27,270 test sample points); the classifier evaluation accuracy was improved from 95.33% to 98.26%, and the average running time of the model with the test set data was 44 ms per slice. the segmentation results can automatically generate a complete vascular tree model with an average time of 10.8s ± 1 1.6s. The results demonstrate that the proposed method provides fast and accurate 3D visualization of pulmonary vessels, and is promising for more precise and reliable information for pneumonoconiosis patients.

Automated vessel segmentation in lung CT and CTA images via deep neural networks

The distribution of pulmonary vessels in computed tomography (CT) and computed tomography angiography (CTA) images of lung is important for diagnosing disease, formulating surgical plans and pulmonary research. Based on the pulmonary vascular segmentation task of International Symposium on Image Computing and Digital Medicine 2020 challenge, this paper reviews 12 different pulmonary vascular segmentation algorithms of lung CT and CTA images and then objectively evaluates and compares their performances. First, we present the annotated reference dataset of lung CT and CTA images. A subset of the dataset consisting 7,307 slices for training and 3,888 slices for testing was made available for participants. Second, by analyzing the performance comparison of different convolutional neural networks from 12 different institutions for pulmonary vascular segmentation, the reasons for some defects and improvements are summarized. The models are mainly based on U-Net, Attention, GAN, and multi-scale fusion network. The performance is measured in terms of Dice coefficient, over segmentation rate and under segmentation rate. Finally, we discuss several proposed methods to improve the pulmonary vessel segmentation results using deep neural networks. By comparing with the annotated ground truth from both lung CT and CTA images, most of 12 deep neural network algorithms do an admirable job in pulmonary vascular extraction and segmentation with the dice coefficients ranging from 0.70 to 0.85. The dice coefficients for the top three algorithms are about 0.80. Study results show that integrating methods that consider spatial information, fuse multi-scale feature map, or have an excellent post-processing to deep neural network training and optimization process are significant for further improving the accuracy of pulmonary vascular segmentation.

Engineering Functional Vasculature in Decellularized Lungs Depends on Comprehensive Endothelial Cell Tropism.

Tissue engineering using decellularized whole lungs as matrix scaffolds began as a promise for creating autologous transplantable lungs for patients with end-stage lung disease and can also be used to study strategies for lung regeneration. Vascularization remains a critical component for all solid organ bioengineering, yet there has been limited success in generating functional re-endothelialization of most pulmonary vascular segments. We evaluated recellularization of the blood vessel conduits of acellular mouse scaffolds with highly proliferating, rat pulmonary microvascular endothelial progenitor cells (RMEPCs), pulmonary arterial endothelial cells (PAECs) or microvascular endothelial cells (MVECs). After 8 days of pulsatile perfusion, histological analysis showed that PAECs and MVECs possessed selective tropism for larger vessels or microvasculature, respectively. In contrast, RMEPCs lacked site preference and repopulated all vascular segments. RMEPC-derived endothelium exhibited thrombomodulin activity, expression of junctional genes, ability to synthesize endothelial signaling molecules, and formation of a restrictive barrier. The RMEPC phenotype described here could be useful for identifying endothelial progenitors suitable for efficient vascular organ and tissue engineering, regeneration and repair.

ИССЛЕДОВАНИЕ РОЛИ NA+, K+, 2CL- - КОТРАНСПОРТА В РЕГУЛЯЦИИ ТОНУСА ЛЕГОЧНОЙ АРТЕРИИ

Purpose. We studied the role of Na+, K+, 2Cl- cotransport (NKCC) in contractile activity of pulmonary artery seg- ments with intact endothelium induced by incubation in nonisosmotic solutions. Materials and methods. The influence of nonisosmotic solutions and blocker of NKCC on vascular segments mechanical tension was studied in isometric regime with organ bath technique performed with the 4-channel Myobath II and software complex LAB-TRAX-4/16 (Germany). Hyperosmotic shrinkage was induced by adding 50-300 mM su- crose to the Krebs solution, the hypoosmotic environment was created by reducing the concentration of NaCl from 70 mM to 40 mM. Bumetanide was used as an NKCC blocker. The amplitude of the contractile responses was evaluated as a percentage of the control contraction in highpotassium solution. Results. The addition of 50-300 mM sucrose to the Krebs incubation solution caused a development of dose- dependent of sustained contractile responses. The amplitude of hyperosmotic striction increased with inhibition of NKCC. Incubation of segments in hypoosmotic solution caused the development of transient contractile responses, the amplitude of which decreased in the presence of NKCC inhibitor. Conclusion. Iincubation of pulmonary artery vascular segments in hyper- and hyposmotic solutions induces con- tractile responses, the amplitude of which depends on the NKCC activity.

Resolving tractions across cell‐cell adhesion reveals the role of intercellular shear in plithotaxis

BackgroundEndothelial cells form a selectively permeable layer by attaching to their neighbors through various adhesion molecules. Some of these molecules are interlinked through cytoskeletal filaments and exposed to cytoskeletal forces. Importantly, cytoskeletal forces are balanced continuously at the cell‐cell and cell‐substrate adhesion maintaining monolayer homeostasis and preventing cellular motion. Using Monolayer Stress Microscopy, we have previously quantified cytoskeletal forces across cellular monolayers. We identified that locations with orientation‐dependent (or anisotropic) tension exhibited motion along the orientation of highest tension (or equivalently, the orientation of minimal shear forces). This phenomenon, known as plithotaxis, would occur if the intercellular junctions are unable to support shear forces. Here we examine the validity of this structural basis for plithotaxis in cultured cell monolayers.MethodsWe seeded clusters of pulmonary endothelial cells on a collagen‐coated hydrogel and quantified the cell‐substrate forces by analyzing the motion of beads embedded within the gel. Using these forces, we analyzed mechanical equilibrium of the cell monolayer and recovered a two‐dimensional monolayer stress tensor (or cytoskeletal forces). By segmenting phase contrast image of the cell monolayer, we detected the location of the intercellular boundaries. The monolayer stress tensor at the intercellular boundaries was then resolved into Fn and Ft. Using these forces, we then computed a two‐dimensional moment tensor for each cell. This moment tensor is then used in assessing a novel definition of plithotaxis, not as a property of discrete points but instead, as a property of each cell within the monolayer.ResultsFn and Ft exhibited unique characteristics for endothelial cells from distinct pulmonary vascular segments, including arteries (PAEC), microvessels (PMVEC) and veins (PVEC). The highest contrast was seen between PAECs and PMVECs. PMVECs exhibited the fewest intercellular segments with negative Fn, Ft was largest and most comparable in magnitude to Fn, and the cells appeared to move along the principal axis of the moment tensor, indicating that intercellular shear forces are not negligible and plithotaxis can be defined at the lengthscale of a cell. Moreover, plithotaxis was more pronounced for the cells that had higher median Ft/Fn, indicating that intercellular shear force and plithotaxis are in fact positively correlated.ConclusionPlithotaxis arise not from inability but instead from the strong ability of intercellular junctions to support shear forces. Our work opens new research avenues for systematic examination of the relationship between structure and physical function of the intercellular junctions.Support or Funding InformationAbraham Mitchell Cancer Research Fund, Research and Scholarly Development Grant, P01 HL66299 (NIH/NHLBI), F32 HL144040‐01 (NHLBI), University of South Alabama Honors College Scholarship.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

An Approach for Pulmonary Vascular Extraction from Chest CT Images.

Pulmonary vascular extraction from chest CT images plays an important role in the diagnosis of lung disease. To improve the accuracy rate of pulmonary vascular segmentation, a new pulmonary vascular extraction approach is proposed in this study. First, the lung tissue is extracted from chest CT images by region-growing and maximum between-class variance methods. Then the holes of the extracted region are filled by morphological operations to obtain complete lung region. Second, the points of the pulmonary vascular of the middle slice of the chest CT images are extracted as the original seed points. Finally, the seed points are spread throughout the lung region based on the fast marching method to extract the pulmonary vascular in the gradient image. Results of pulmonary vascular extraction from chest CT image datasets provided by the introduced approach are presented and discussed. Based on the ground truth pixels and the resulting quality measures, it can be concluded that the average accuracy of this approach is about 90%. Extensive experiments demonstrate that the proposed method has achieved the best performance in pulmonary vascular extraction compared with other two widely used methods.

3D Multi-Scale Pulmonary Vascular Segmentation Algorithm Based on Multi-Label MRF Optimization

3D Multi-Scale Pulmonary Vascular Segmentation Algorithm Based on Multi-Label MRF Optimization

Findings Associated with Pulmonary Hypertension: CT Angiography Based Study

Pulmonary hypertension (PH) is a complex disorder and may be related to a variety of diseases. It may arise in association with chronic thromboembolic pulmonary hypertension (CTEPH) or pulmonary embolism (PE). Knowledge of the radiological features is required to characterize and accurately diagnose the conditions and may improve the outcome. This study was designed to evaluate the clinical characteristics and the computerized tomography angiography findings in patients with PH, PE and CTEPH. Contrast-enhanced CT scans were acquired in 55 Sudanese patients with PE, 20 patients with PH, 25 patients with CTEPH and 50 normal subjects who were considered as control group. The CT diagnostic criteria for all cases were characterized. The clinical signs, parenchymal abnormalities, pulmonary tree and cardiac segments in all groups were characterized and compared with the control group. The results showed that the most common clinical characteristics were found to be chest pain, dyspnea, lower limb swelling, tachycardia and syncope which were correlated significantly with the presence of the disease. In all patients groups, the pulmonary vascular segments, cardiac segments and lung parenchyma changes were detected and were significantly different from the normal control subjects at p ≤ 0.01. It was found that CT angiography has a significant role in the diagnostic evaluation of these groups of patients. CT imaging is acceptably used in diagnosis, defining cause, quantifying heart segments and parenchyma changes in order to assess the feasibility of surgery, monitoring and therapeutic planning.

Segmentation of pulmonary vascular tree from 3D CT thorax scans

This paper considers the problem of pulmonary vessels identification in thoracic 3D CT scans. In particular, the method for pulmonary vascular tree segmentation is introduced. The main idea behind the introduced method is to extract both thoracic trees together (i.e. the vascular tree and the airway tree) and then remove airway walls. Therefore, firstly segmentation of vessels and airway walls is performed using 3D region growing where the growth of the region is guided and constrained by results of random walk segmentation applied to consecutive CT slices. In particular, results of random walk segmentation of one slice are used to determine seeds for random walk segmentation of the following slice. Next step is airway tree segmentation using 3D region growing algorithm guided and constrained by the morphological gradient. Finally, morphological processing is applied in order to extend airway lumen onto airway walls and remove the overlapping regions. The main steps of the proposed approach are described in detail. Results of pulmonary vascular tree segmentation from example thoracic volumetric CT datasets provided by the introduced approach are presented and discussed. Based on a manually selected and radiologist's verified ground truth pixels and the resulting quality measures it can be concluded, that the average accuracy of the introduced approach is about 90%.

Pulmonary Embolism Vascular Segmentation in CT Angiography

Pulmonary embolism mortality rate is very high disease, especially for acute pulmonary embolism with other disease mortality. Treatment of pulmonary embolism method is mainly to drug therapy. Pulmonary embolism in the acute phase of drug treatment strategies is mainly for anticoagulation and thrombolysis. Through the lungs scanning, decision of thrombolysis success or fail. This paper puts forward a kind of algorithm that analysis quantitatively the degree of thrombolysis by the computer. Firstly, making use of the Hessians eigenvalue and diffuse equation enhance pulmonary embolism vessel, and then pulmonary embolism vessel segmentation based on a LEVEL-SET. At lastly, According to the eigenvalue of blood vessels, remove the blood vessels edge line, and the rest relevant to edge point. According to the each point of eigenvector and eigenvalue, quantitative analysis of the degree of thrombolysis.

Vascular segmentation for lung CT images based on fractional differential enhancement

In order to improve the accuracy of automatic vascular segmentation in CT lung images,after researching image enhancement,segmentation method and the enhancing ability of the fractional differential operator toward image details,a local sub-regional segmentation method based on fractional differential enhancing was proposed.This method enhanced the lung CT images with fractional differential operator firstly,and then the optimal threshold acquired under two control indexes was used for vascular segmentation in the local region.The experimental results show that the proposed method can effectively extract the vascular network in which the blood vessels have more detailed information.And compared to traditional pulmonary vascular segmentation method,it has more accurate segmentation ability of the pulmonary vascular in CT images.

Abstract 4567: Functional Intraoperative Pulmonary Blood Flow Study is a Sensitive Predictor of Right Ventricular Pressure and Successful VSD Closure for Following Complete Uniforcalization in Patients with Pulmonary Atresia with Ventricular Septal Defect and Major Aortopulmonary Collaterals

OBJECTIVE: We hypothesized mean pulmonary artery (PA) pressure obtained from an intraoperative pulmonary flow study would better predict the ability to close the ventricular septal defect (VSD) and better predict postoperative right ventricular systolic pressure (RSVP) than classic anatomical parameters after complete uniforcalization in patients with pulmonary atresia, VSD, and major aortopulmonary collaterals. METHODS: Sixteen consecutive patients (median, 11 mo, range 2 mo – 16 yrs) underwent one-stage (75%) or staged (25%) uniforcalization between 1/03 and 8/07. Intraoperative functional pulmonary blood flow study was achieved by inserting an arterial cannula in a reconstructed central PA. Flow was increased to 2.5 L/min/m2 while measuring PA pressure. RVSP and systemic systolic pressure (SBP) were recorded after VSD closure. Total neopulmonary artery index (TNPAI) (MAPCA + native PA index), total incorporated pulmonary vascular segments, and pulmonary segment artery ratio (PSAR) (ratio of incorporated segment to 18) were analyzed. Spearman rank correlation and area under the receiver operator characteristics curve (ROC-AUC) were used. RESULTS: The mean PA pressure on flow study was 21.8+/−6.2 mmHg (range, 11–31). Three patients had a pressure of > 30 mmHg. The VSD was closed in 14 (87%). One patient with flow study mean PA pressure of 25 mmHg had suprasystemic RVSP and underwent intraoperative VSD fenestration. One with a flow study mean PA pressure of 30 mmHg had a prospective fenestrated VSD patch placed. There is a weak negative correlation between TNPAI and the flow study PA pressure (rho=−0.4, p=0.12). The flow study mean PA pressure was correlated with post-repair RVSP (rho=0.72, p=0.0027), and with RVSP/SBP ratio (rho=0.67, p=0.0063). TNPAI, total incorporated segments, and PSAR were not correlated with the postoperative RVSP or RVSP/SBP ratio. Flow study mean PA pressure had the highest sensitivity in predicting VSD closure: ROC-AUC (0.82) vs. TNPAI (0.46), pulmonary segment (0.64), and PSAR (0.64). CONCLUSIONS: Intraoperative pulmonary flow study predicted the ability of VSD closure better than total incorporated segments, TNPAI, and PSAR. Flow study mean PA pressure highly correlated with postoperative RVSP and RVSP/SBP ratio.

Differential responses of pulmonary endothelial phenotypes to cyclical stretch

Endothelial phenotypes derived from different pulmonary vascular segments have markedly different permeability response to inflammatory agonists, but their responses to mechanical strain have not been characterized. Therefore, we evaluated the effect of cyclical stretch on cell shape, cell membrane wounding, and junctional β-catenin in rat pulmonary artery (RPAEC) and microvascular (RPMVEC) endothelial cell monolayers. After 24 h of 24% uniaxial strain at 40 cycles/min, RPAEC but not RPMVEC reoriented transverse to the axis of strain. Total β-catenin increased in RPAEC but decreased in RPMVEC. Transient plasma membrane wounding was produced by cyclical biaxial strain of 34% or by scratching of monolayers with a needle and was indicated by retention of lysine fixable fluorescent 70 kDa dextran. Junctional β-catenin was quantified by fluorescence intensity and image analysis. β-catenin fluorescence was significantly lower in wounded cells than in adjacent uninjured cells in both phenotypes, and the decrease was significantly greater in RPAEC compared to RPMVEC in both scratched (57% vs. 30%) and stretched (55% vs. 37%) cells. Using immunoprecipitation, VE-cadherin-associated β-catenin decreased significantly in RPAEC (61%) but E-cadherin-associated β-catenin was not significantly decreased in RPMVEC after 34% biaxial cyclical strain. These data suggest that RPAEC more readily remodel cell–cell adhesions during cyclical stretch than RPMVEC and that a reduced intercellular adhesion adjacent to wounded cells could serve as transvascular leak sites in both phenotypes.

Pulmonary circulation after biventricular repair in patients with major systemic-to-pulmonary collateral arteries.

To determine factors affecting postoperative pulmonary circulation in patients with major systemic-to-pulmonary collateral arteries. A total of 48 patients underwent biventricular repair subsequent to unifocalization at ages in the range 1-34 years. The preparative procedures consisted of ligation of the collateral arteries in 6, plasty to the pulmonary arteries using no artificial materials in 12 and extensive reconstruction using heterologous pericardial tubes in 30. The number of the pulmonary vascular segments unifocalized was 9-18 (16 +/- 3). The amount of flow draining via residual minute systemic-to-pulmonary collaterals measured at the time of repair was 4-58% (24 +/- 16%) of the total perfusion by the cardiopulmonary bypass machine. This value was 40 +/- 16% in 5 patients dying in the short term after repair. The number of segments was nine or ten after unifocalization in 2 of these. Another 4 patients died in the longer term, 3 of these with CATCH 22 syndrome dying because of pulmonary hypertension. Postoperative catheterization demonstrated mean pulmonary arterial pressures in the range 8-40 (21 +/- 9) mmHg and pulmonary resistance in the range 1.7-10 (5.0 +/- 2.1) units/m2. Pulmonary resistance was correlated statistically to age at repair (r = 0.77), the number of pulmonary vascular segments (r = -0.41) and to percent collateral flow (r = 0.48). The use of a heterologous pericardial tube for unifocalization was also related probably to higher pulmonary resistance. It is essential to accomplish effective unifocalizations followed by earlier definitive repair so as to establish better pulmonary circulation.

Surgery for congential heart disease Unifocalization for pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries

To extend the indications for corrective operation in patients with pulmonary atresia, ventricular septal defect, and major aortopulmonary collateral arteries, surgical procedures were done to unify the blood sources for pulmonary perfusion. Since December 1985, 50 patients have undergone unifocalization at ages from 2 months to 26 years with a mean of 6 ± 7 years. In total, 84 staged unifocalization procedures and 5 other palliative procedures were done in 49 patients. These included several operative procedures: simple ligation of major aortopulmonary collateral arteries in 8; pulmonary angioplasty in 29 including reconstruction of the pulmonary arterial tree by direct anastomosis or interposition between the central pulmonary arteries and the intrapulmonary arteries; construction of artificial central pulmonary arteries with use of a xenograft pericardial tube graft in 36 with no native central pulmonary arteries detected; and construction of supplemental central pulmonary arteries also with use of a pericardial tube graft in 10. The pericardial tube graft, if used, was anastomosed to the intrapulmonary arteries on one end and connected to a prosthetic tube on the other end so as to perfuse the reconstructed pulmonary arteries. The anastomosis was made inside the lung through the divided interlobar fissure. Five patients died after operation among those undergoing these 89 preparative operative procedures. Deaths were related either to bleeding caused by anticoagulation therapy administered to prevent thrombosis within the xenograft pericardial tube graft used or to progressive congestive heart failure as a result of an excessive amount of pulmonary blood flow. Twenty-six patients have undergone intracardiac repair after previous unifocalization. In 16 patients the artificial central pulmonary arteries surgically constructed were connected to each other and then an external conduit was placed. In another patient, intracardiac repair and unifocalization could be concomitantly achieved via a median sternotomy. The right ventricle to left ventricle systolic pressure ratio immediately after intracardiac repair in 27 patients ranged from 0.24 to 0.91 with a mean of 0.54 ± 0.17. One patient (4%) died shortly after intracardiac repair because of thrombosis within the pulmonary arteries. Postoperative catheterization showed that pulmonary vascular resistance was correlated significantly with the number of pulmonary vascular segments functioning rather than with the condition of the central pulmonary arteries. We conclude that surgical unifocalization is a feasible procedure before subsequent intracardiac repair, even in patients with critically hypoplastic or absent central pulmonary arteries. (J T horac C ardiovasc S urg 1996;112:392-402)

Results of unifocalization for pulmonary atresia, ventricular septal defect and major aortopulmonary collateral arteries: patency of pulmonary vascular segments.

Unifocalization, a surgical technique to unifocalize the pulmonary blood supply in patients with pulmonary atresia, ventricular septal defect and major aortopulmonary collateral arteries, is a useful preparative operation to extend the indication for corrective surgery. The preoperative and postoperative pulmonary angiograms of 51 patients (aged 3 months-26 years at first unifocalization, 29 males, 22 females), who underwent a total of 96 unifocalizations from December 1985 to July 1994, were studied to assess the effectiveness of each procedure of unifocalization. The procedures of unifocalization were ligation (9), angioplasty (6), direct anastomosis (25), bridging (6), additional central pulmonary artery creation (9), central pulmonary artery creation (36) and thrombectomy (5). Altogether 125 anastomoses were made, and the patency of 101 (80.2%) anastomoses was confirmed, 24 (19.2%) were shown to be occluded. The patency rate of the anastomoses between xenograft rolls and intrapulmonary arteries was 79.5% (70/88), while that between native central pulmonary arteries and intrapulmonary arteries was 83.8% (31/37; N. S.). The patency rate of the anastomoses involving intrahilar arteries was 88.0% (44/50), while that for the group involving extrahilar arteries only was 71.9% (46/64; P < 0.05). It is concluded that 1) unifocalization with the reconstruction of central pulmonary arteries using a pericardial roll is a useful method for patients with absent or hypoplastic central pulmonary arteries, 2) it is preferable to divide the fissures of lung in anastomosing pulmonary arteries of arborization abnormalities.

Review of the long-term course of 52 patients with pulmonary atresia and ventricular septal defect. Anatomical and surgical considerations.

This study reviews the long-term course of 52 patients with pulmonary atresia and ventricular septal defect seen in a single institution and followed for a mean period of 8.6 years (range 2 days to 20 years). Before the first operation, pulmonary blood supply was provided by ductus arteriosus supplying confluent pulmonary arteries in 26 patients (50%, group I), and was partially or entirely dependent on systemic collateral arteries in the other 26 patients (group II). The angiographic mean ratio of diameters of the right and left pulmonary artery/descending aorta (McGoon ratio) was significantly lower in group II than in group I, 0.76 +/- 0.42 vs 1.04 +/- 0.17 (P = 0.006). Severe arborization defects (with fewer than 10 pulmonary vascular segments connected to central pulmonary arteries) were present only in group II patients (eight patients: 15%), six of whom had congenital absence of the central pulmonary arteries. Corrective surgery was performed in 23 patients (44%, 14 in group I, nine in group II). All but one, who died later, had a McGoon ratio > or = 1 (mean 1.19 +/- 0.18) at time of repair. There was one hospital death (4%) and two late deaths (9%). All but one of the surviving corrected patients were in functional class I or II. Conduit replacement reoperation was performed in three patients (14%), 6, 10 and 13 years, respectively, after repair. At the end of the study, among the 37 patients (71%) who were alive (17 in group I, 20 in group II), 20 (39%) were corrected (12 in group I, eight in group II), four await corrective surgery, and six (11.5%) are estimated inoperable (all in group II) because of very hypoplastic or absent pulmonary arteries. This study confirms the estimated rate in the published literature of long-term survival in patients with pulmonary atresia and ventricular septal defect, and the good results of corrective surgery whenever the size and distribution of pulmonary arteries are satisfactory. The problem of very hypoplastic pulmonary arteries and severe arborization defects remains contentious.

Pulmonary vasculature: single breath-hold MR imaging with phased-array coils.

The authors obtained magnetic resonance images of the pulmonary vasculature with reduced artifacts caused by cardiac and respiratory motion by acquiring a series of moderately thin sections in a single breath-hold with an ultrafast gradient-echo pulse sequence. The series of two-dimensional images was postprocessed with a maximum-intensity projection algorithm. Time-of-flight inflow enhancement increased the signal intensity of arteries and veins while radiofrequency phase spoiling produced limited stationary spin suppression of the chest wall. Moderately thin (8-mm) section thicknesses were used to attain the resolution necessary to visualize smaller pulmonary vascular segments up to the chest wall while the number of acquired sections was minimized. Because the body coil did not provide an adequate signal-to-noise ratio (S/N) for a single excitation and thin-section acquisitions, phased-array coils covering either the right or left lung were used to single breath-holds prevented the misregistration and blurring that occurred in examinations performed with multiple breath-holds.

The structure of the pulmonary circulation in tetralogy of Fallot with pulmonary atresia: A quantitative cineangiographic study

Cineangiograms of 172 patients with tetralogy of Fallot and pulmonary atresia were qualitatively and quantitatively analyzed retrospectively. Twenty-eight (16%) patients had congenital absence of the central and unbranched hilar portions of the left or right pulmonary artery or both, and thus had congenitally nonconfluent pulmonary arteries. Five additional patients (3%) with originally confluent pulmonary arteries had nonconfluent ones because of an end-to-end surgical shunt, as did seven others (4%) because of thrombosis of one pulmonary artery. Among the 132 patients with confluent right and left pulmonary arteries, 70 (53% of 132) had incomplete arborization (distribution) of one or both, as did 23 (82% of 28) of those with congenitally nonconfluent pulmonary arteries (P for difference = 0.005). Ten (36% of 28) of the latter group had fewer than 10 pulmonary vascular segments (normal is 20) in continuity with central pulmonary arteries, compared with four (3%) of the former group. The proximal left and right pulmonary arteries were small but variable in size in all groups (median value 1.05 McGoon ratio), but were largest in the patients with confluent pulmonary arteries. Seventy-nine (60% of 132) patients with confluent left and right pulmonary arteries had large aortopulmonary collateral arteries, as did 100% of those with congenitally nonconfluent pulmonary arteries (P less than 0.001). The number of large aortopulmonary collateral arteries correlated inversely with the completeness of arborization of the left and right pulmonary arteries (P less than 0.0001). Inferences: Most patients with tetralogy and pulmonary atresia have gross morphologic abnormalities in the pulmonary vasculature and differ quantitatively in this regard from those with tetralogy and pulmonary stenosis. The prevalences of the various types of these abnormalities are considerably interrelated.

Response of pulmonary vascular segments to angiotensin and norepinephrine

Response of pulmonary vascular segments to angiotensin and norepinephrine