Fluid In Sinuses Research Articles

Variation of the quantity of lymph in the subcutaneous sinuses in the Common frog (<i>Rana temporaria</i>)

Seasonal variation in the amount of fluid in the subcutaneous lymphatic sinuses of the common frog (Rana temporaria) and differences in the dynamics of its mass in adult males and females from autumn to spring are shown. The hypothesis that enlarged lymphatic sinuses (one of the elements of the “nuptial attire” of R. temporaria) can be used by small frogs to gain competitive advantages in assortative pair selection during reproduction is tested.

Pitfalls in Oncologic Imaging of the Pericardium on CT and PET/CT

In the oncologic setting, misinterpretation of fluid in pericardial recesses as mediastinal adenopathy or benign pericardial findings as malignant can lead to inaccurate staging and inappropriate management. Knowledge of normal pericardial anatomy, imaging features to differentiate fluid in pericardial sinuses and recesses from mediastinal adenopathy and potential pitfalls in imaging of the pericardium on CT and PET/CT is important to avoid misinterpretation.

Clear Sinus Sign on Head CT Scan: Reliable Criterion to Exclude Paranasal Sinus Fracture

The clear sinus sign has been described in facial computed tomography (CT) as an indication of the absence of fluid in the paranasal sinuses. It is a highly reliable criterion to exclude fracture involving the paranasal sinus wall. Very scarce data on this sign on head CT scan is currently available. We conducted the present study to assess the usefulness of the clear sinus sign on head CT scan to exclude paranasal sinus fracture. A retrospective cross-sectional review of the medical records and head and facial CT images was performed for 80 trauma patients with a total of 640 paranasal sinuses. The presence and absence of paranasal sinus fracture was recorded and analyzed. The clear sinus sign was found in 207 paranasal sinuses (32.3%) on head CT, and none of these had a paranasal sinus fracture (P<.001). The presence of the clear sinus sign on head CT scans is an excellent indication for exclusion of a paranasal sinus fracture in trauma patients.

Diagnosis of drowning by summation of sodium, potassium, and chloride ion levels in sphenoidal sinus fluid: Differentiating between freshwater and seawater drowning and its application to brackish water and bathtub deaths

Analysis of ions in sphenoidal fluid can be a useful index for the diagnosis of drowning. We evaluated the reference ranges of non-drowning cases using statistical methods and three indices: sodium ion (Na+), summation of sodium and potassium ions (SUMNa+K), and summation of sodium, potassium and chloride ions (SUMNa+K+Cl). The reference ranges were 96≤Na+<152, 139≤SUMNa+K<179, 243≤SUMNa+K+Cl<311(mEq/L), respectively. Victim indices outside of the reference ranges indicate that the victim probably inspired water with higher or lower ion concentrations than those of body fluid in sphenoidal sinuses. Compared to the SUMNa+K+Cl index, the Na+ and SUMNa+K indices could distinguish among seawater drowning, freshwater drowning, and non-drowning. In drowning cases, sphenoidal fluid volume and time since death were not correlated, which suggests that water does not enter the sphenoidal sinuses after death and there is a different process for water accumulation in drowning and non-drowning cases. In bathtub cases, this method was not valid for the estimation of inspired water. Although it is necessary to observe the classical signs of drowning, this method is suitable for the estimation of drowning, especially in cases where pleural fluid or diatom tests are not available.

Olfactory Neuroblastoma

This 57 year-old woman presented with a seizure. She had a history of attending the ENT and neurosurgical departments for more than a decade. At the time of her initial presentation many years prior, her main complaint was of nasal congestion. A nasopharyngeal biopsy confirmed an olfactory neuroblastoma.&#x0D; &#x0D; Olfactory neuroblastoma is an uncommon slow growing tumour of the nasal cavity with no established etiological basis. With a neuroectodermal origin, it arises from the olfactory epithelium of the upper nasal cavity.1 Most cases arise from the cribriform plate, upper third of the nasal septum, superior turbinates or anterior ethmoidal air cells. However, it typically presents late when multiple structures are involved, which may include the orbits and intracranial compartments.2&#x0D; &#x0D; Accounting for approximately 2% of sinonasal tumors, although often late to present, ironically only a minority of patients experience anosmia.3 The commonest complaint at initial presentation is nasal blockage accounting for nearly a quarter of cases, with headache and epistaxis the next most frequent symptoms.1&#x0D; &#x0D; Multi-modality imaging is essential in that the most recognized management of this infrequent tumor is a combination of craniofacial surgery and radiotherapy. The imaging pathway in this case was typical, with CT and MRI complementing each other in maximizing tumor delineation. Computed Tomography has superior definition is reviewing bony involvement which is a typical finding, whereas MRI has superiority in evaluating the extent of soft tissue invasion and establishing tumor boundaries against post obstruction fluid in the paranasal sinuses.3 In this case the CT illustrates the gross destruction of the skull base, orbital and sinus margins. (Figure 1-4) The MRI outlines the extension of disease involving the pituitary fossa, brainstem and frontal sinus invasion. (Figures 5 and 6)&#x0D; &#x0D;

Bathtub drowning: An 11-year retrospective study in the state of Maryland

A bathtub drowning is one of the leading causes of death in a bathtub. The purpose of this study was to evaluate how reliable the drowning-related signs could be for identifying a bathtub drowning in the cases of death in the bathtub. Performing a retrospective review of 92 deaths in the bathtub in Maryland, 71.7 percent were the presence of bathtub drowning and 28.3 percent were the absence of bathtub drowning. Three leading contributory causes of death were cardiovascular disease, drug/alcohol-related death, and seizure disorder in both groups. There was a statistically significant difference between the groups in relation to a history of recovery from the water (95.5% and 38.4%, p<0.001), foam in the air way (33.3% and 15.4%, p<0.05), watery fluid in the sphenoid sinuses (81.8% and 11.5%, p<0.05), hyperinflated lungs (36.4% and 3.8%, p<0.01), and watery fluid in the stomach contents (40.9% and 3.8%, p<0.01). More than triple overlapped drowning-related signs could be beneficial for the diagnosis of a bathtub drowning. A comprehensive investigation incorporating a thorough scene investigation, gathering of the victim's medical and psychosocial history, and a meticulous full autopsy is necessary to elucidate both the cause and manner of death in these cases of death in the bathtub.

Post-mortem evaluation of drowning with whole body CT

PurposeThe aim of this study is to investigate the value of whole body computed tomography (WB-CT) in bodies recovered from water by analysis of the imaging findings after drowning. MethodsThe bodies of 41 drowning victims and 9 persons who died from mechanical asphyxia by hanging underwent post-mortem whole body computed tomography. Results and conclusionsExcessive fluid in the paranasal sinuses (98%), nasal pharynx (98%), oropharynx (95%), trachea (83%), ground glass opacities in the lung (89%), pleural fluid (71%), pericardial fluid (59%), esophageal fluid (81%), stomach fluid and distension (71%), duodenal (34%) and jejunal distension (31%) were the most frequent drowning related imaging findings which significantly differed from the group of mechanical asphyxia by hanging. In cases of fresh water drowning hemodilution was present in 79%. New and up to now unpublished findings were lower density in the spleen, indicative for hemodilution and detection of a pronounced amount of pericardial fluid, only seen in drowning victims.

Can post-mortem CT reliably distinguish between drowning and non-drowning asphyxiation?

The aim of this study is to evaluate whether previously reported post-mortem CT findings in drowning can reliably distinguish drowning from asphyxiation by any other manner. Cases (n = 14) were corpses with cause of death determined as drowning by concordant autopsy findings and physical and circumstantial evidence. Controls (n = 11) were corpses in which the cause of death was defined as asphyxiation by any other manner than submersion in a liquid. Images were evaluated for the presence of fluid in paranasal sinuses, mastoid air cells and lower airways, frothy foam in the upper airways, ground-glass opacity of the lung parenchyma, the height of the right hemi-diaphragm, the interpulmonary distance at the level of the aortic valve, the mean density of intracardiac blood, and gastric and esophageal contents. Descriptive statistics, Fisher's exact test, and Student's t test were used when appropriate. Only the height of the right hemi-diaphragm differed significantly (p = 0.045) between cases (mean 5.4) and controls (mean 4.3). Other findings were not significantly different between both groups. Our results indicate that it is not possible to reliably distinguish drowning from non-drowning asphyxiation on CT, because many findings in drowning were also present in non-drowning asphyxiation. CT indicators for drowning as the cause of death should therefore be defined with great caution, keeping in mind that they are not specific to only a single cause of death.

Role of virtopsy in the post-mortem diagnosis of drowning

Due to admitted limits of autopsy-based studies in the diagnosis of drowning, virtopsy is considered the new imaging horizon in these post-mortem studies. The aim of our study was to evaluate the role of virtopsy performed through computed tomography (CT) in the forensic diagnosis of drowning. We retrospectively examined the CT data of four cadavers recovered from sea water and suspected to have died by drowning. Each patient underwent a full-body post-mortem CT scan, and then a traditional autopsy. All the cadavers showed fluid in the airways and patchy ground-glass opacities in the lung. Only one patient had no fluid in the digestive tract; this patient had a left parietal bone fracture with a large gap and other multiple bone fractures (nose, clavicle, first rib and patella). One of the three patients who had fluid in the digestive tract had no fluid in the paranasal sinuses. This latter patient showed cerebral oedema with subarachnoid and intraventricular haemorrhage, multiple bone fractures (orbital floor, ribs, sacrum and acetabular edge) and air in the heart, in the aorta and in bowel loops. To date, there are no autopsy findings pathognomonic of drowning. This study proves that virtopsy is a useful tool in the diagnosis of drowning in that it allows us to understand if the victim was alive or dead when he entered the water and if the cause of death was drowning.

Diagnosis of drowning using post-mortem computed tomography - state of the art.

Recent studies using post-mortem computed tomography (PMCT) have suggested this imaging modality is of value in the positive diagnosis of drowning. We summarize the data from the literature regarding the diagnostic value of CT in cases of drowning. We performed an all-language search of literature published from 1999 to 2013 with the key words "post-mortem CT scan", "drowning and CT scan", "near-drowning diagnosis", and "drowning diagnosis". Only 11 articles, whose data enabled complementary statistical analysis, were included. The presence of fluid and sediment in paranasal sinuses appear to be the determinants of the diagnosis of drowning. The presence of fluid in the sinuses had a sensitivity of 100%, and of 90% in the trachea and main bronchi. The results were completed by the high specificity of the presence of sediment in the paranasal sinuses, upper airways and stomach, which was 100% for all three. Haemodilution was present in cases of drowning (p < 0.001). The values made it possible to formulate a decision algorithm for the diagnosis of drowning.

Arachnoid granulations may control heat exchange between intracranial dural sinuses and cerebrospinal fluid

Selective brain cooling is a system in a human that protects the brain from hyperthermia. Cool venous blood from head skin and upper respiratory tract drains into intracranial dural sinuses. In that region, cool blood in the dural sinuses decreases the temperature of the cerebrospinal fluid. Cerebrospinal fluid provides brain cooling. All cortical arteries to the brain pass the cerebrospinal fluid compartment. Also cerebrospinal fluid washes cortical nervous tissue. To provide optimal temperature for the brain cortex, heat exchange between cerebrospinal fluid and venous blood in dural sinuses should be well controlled. Head skin is in direct contact with the outside, and significant heat exchanges may occur within dural sinuses. A barrier made of dura mater and arachnoid mater has been proposed to transmit heat from dural sinuses to the cerebrospinal fluid. However, this barrier is a mechanical barrier and can’t optimize the temperature of cerebrospinal fluid. Also it has two laminas (dura mater and arachnoid mater) and dura mater has a high vascularization. Therefore, this barrier may obstruct heat exchange. In this hypothetical paper, I offer arachnoid granulations as a functional barrier for heat exchange between blood in dural sinuses and cerebrospinal fluid. Arachnoid granulations are invaginations of arachnoid mater to the dural sinuses. Cerebrospinal fluid passes to the dural sinuses via arachnoid granulations. An arachnoid granulation provides a very thin wall between two compartments and may transmit heat effectively. Also arachnoid granulations may control cerebrospinal fluid flow to the dural sinuses according to temperature differences between two compartments. It is worth researching whether there are any functional or histological differences of the arachnoid granulations between people living in cold and hot places. There may also be an association between pathologies such as migraine and pseudotumor cerebri and this possible control mechanism.

The Significance of Fluid in the Sphenoid Sinuses in Death by Drowning

129 pISSN 1225-0589 eISSN 2287-2078 cCopyright 2013 by the Korean Society for Legal Medicine This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Korean J Leg Med 2013;37:129-133 http://dx.doi.org/10.7580/kjlm.2013.37.3.129

Ultrasonographic Evaluation of Sinusitis During Microgravity in a Novel Animal Model

To develop an animal model of rhinosinusitis in microgravity, to characterize the behavior of intracavitary fluid in microgravity, and to assess the accuracy of ultrasonographic (US) diagnosis in microgravity. An animal model of acute sinusitis was developed in anesthetized swine by creating a window into a frontal sinus to allow unilateral catheter placement and injection of fluid. We performed US examinations in normal and microgravity environments on control and sinusitis conditions and recorded these for later interpretation. Henry Ford Hospital and the National Aeronautics and Space Administration (NASA) Microgravity Research Facility in Houston, Texas. Ground (normal-gravity) experiments were conducted on anesthetized swine (n = 4) at Henry Ford Hospital before the microgravity experiments (n = 4) conducted in the NASA Microgravity Research Facility. Ultrasound visualization of fluid cavity. Results of bilateral US examinations before fluid injection demonstrated typical air-filled sinuses. After unilateral injection of 1 mL of fluid, a consistent air-fluid interface was observed on the catheterized side at ground conditions. Microgravity conditions caused the rapid (<10-second) dissolution of the air-fluid interface, associated with uniform dispersion of the fluid to the walls of the sinus. The air-fluid interface reformed on return to normal gravity. The US appearance of fluid in nasal sinuses during microgravity is characterized in the large animal model. On the introduction of microgravity, the typical air-fluid interface disassociates, and fluid lining the sinus can be observed. Such fluid behavior can be used to develop diagnostic criteria for acute bacterial rhinosinusitis in the microgravity environment.

Maxillary sinusitis in patients ventilated for a severe head injury and with nostrils free of any foreign body

BackgroundThis study aims to determine the frequency of maxillary sinusitis in the patients with traumatic head injury and nostrils free of any foreign body. In addition, the sensitivity and specificity of ultrasonography (US) for the detection of the presence of fluid in maxillary sinuses were evaluated. Patients and methodsForty patients with severe traumatic head injury were included in the study. The patients who had displaced maxillary sinus fracture at the medial wall and naso-tracheal and/or naso-gastric tube were excluded. Paranasal computed tomography (CT) was performed along with the routine cranial CT scanning or in case of unknown source of infection and compared with the results of ultrasonographic examination of maxillary sinuses performed by a single radiologist who was unaware of the CT results. In the patients, who had clinical and radiological signs of sinusitis, a trans-nasal puncture was performed using sinoject (SinoJect®, ATOS Medical, Sweden), a spring-activated puncture instrument, to take a sample for microbiologic examination and to drain maxillary sinuses. ResultsEighty-five percent of the patients were tracheotomised on the fifth day (on average) of their intensive care unit (ICU) stay. The frequency of sinusitis in the study group was found to be 32.5% (13 patients). The most frequently isolated species were Pseudomonas spp. (37.5%), Escherichia coli (20.8%) and Peptostreptococcus (16.7%). Five of the aspirates were polymicrobial. The sensitivity, specificity, positive predictive value and negative predictive value of B-mode US, compared with CT for the detection of fluid presence in maxillary sinuses in a 100 maxillary sinus examinations, were 92.2%, 81.6%, 83.9% and 90.9%, respectively. ConclusionMaxillary sinusitis should be considered as a source of infection or sepsis in patients with traumatic head injury because of its high frequency. US is likely to be used as the first-line diagnostic tool for the determination of fluid in maxillary sinuses, especially in patients who do not require CT or cannot be transported to a radiology unit for CT.

Comparison of computed tomography and magnetic resonance imaging for the evaluation of canine intranasal neoplasia

Canine intranasal neoplasia is commonly evaluated using computed tomography to indicate the diagnosis, to determine disease extent, to guide histological sampling location and to plan treatment. With the expanding use of magnetic resonance imaging in veterinary medicine, this modality has been recently applied for the same purpose. The aim of this study was to compare the features of canine intranasal neoplasia using computed tomography and magnetic resonance imaging. Twenty-one dogs with confirmed intranasal neoplasia underwent both computed tomography and magnetic resonance imaging. The images were reviewed retrospectively for the bony and soft tissue features of intranasal neoplasia. Overall computed tomography and magnetic resonance imaging performed very similarly. However, lysis of bones bordering the nasal cavity and mucosal thickening was found on computed tomography images more often than on magnetic resonance images. Small amounts of fluid in the nasal cavity were more often seen on magnetic resonance images. However, fluid in the frontal sinuses was seen equally well with both modalities. We conclude that computed tomography is satisfactory for evaluation of canine intranasal neoplasia, and no clinically relevant benefit is gained using magnetic resonance imaging for intranasal neoplasia without extent into the cranial cavity.

Virtual Autopsy: Two- and Three-dimensional Multidetector CT Findings in Drowning with Autopsy Comparison1

To retrospectively determine the multidetector computed tomographic (CT) virtual autopsy findings of death by drowning in comparison with autopsy findings. The institutional review board of the Armed Forces Institute of Pathology approved this HIPAA-compliant study and did not require informed consent by the next of kin. Total-body multidetector CT was performed, immediately prior to routine autopsy, in 28 consecutive male subjects (mean age, 24.2 years) who died of drowning and a control group of 12 consecutive male subjects (mean age, 50.8 years) who died of sudden death from atherosclerotic coronary artery disease. Images were evaluated for the presence of fluid and sediment in the paranasal sinuses and airways, mastoid air cell fluid, frothy fluid in the airways, pulmonary opacity (ground-glass opacity or airspace consolidation), interlobular septal thickening, and gastric distention and contents (fluid or sediment). Image findings were compared with findings from autopsy reports and photographs. All drowning subjects had fluid in the paranasal sinuses and mastoid air cells and had ground-glass opacity within the lungs. Twenty-six subjects (93%) had fluid in the subglottic trachea and main bronchi. Fourteen subjects (50%) had high-attenuation sediment in the subglottic airways. Frothy fluid in the airways was present in six subjects (21%). Twenty-five (89%) of the drowning subjects had pulmonary ground-glass opacity with septal lines, which was mild with apical and perihilar distribution in 12 subjects, severe and diffuse in nine, posterior and basilar in three, and limited to the apices in one (not assessed in three of 28 subjects because of decomposition). Control subjects showed mastoid cell fluid (25%), sinus fluid (83%), subglottic airway fluid (92%), and pulmonary ground-glass opacity (100%) but did not have evidence of frothy airway fluid or high-attenuation sediment in the airways. The multidetector CT finding of frothy airway fluid or high-attenuation airway sediment is highly suggestive of drowning; multidetector CT findings of pan sinus fluid, mastoid cell fluid, subglottic tracheal and bronchial fluid, and ground-glass opacity within the lung at multidetector CT are supportive of drowning in the appropriate scenario.

Bacterial meningitis resulting in visual impairment and panhypopituitarism

A 30-year-old man presented to his local district general hospital with a week-long history of headache, cough and coryzal symptoms, followed by 24 hours of fever, neck stiffness, photophobia, confusion and agitation. He had no significant previous medical history. Examination revealed a Glasgow Coma Score of 11 (E4, M5, V2), stiff neck, tachypnoea and tachycardia. There were no localizing neurological signs. Mucus was crusted around the nose. The patient was sedated and ventilated in intensive care and given intravenous benzylpenicillin and cefotaxime. He then underwent a computed tomography (CT) head scan, which suggested fluid in the paranasal sinuses and pus filling the maxillary antrum. CSF was turbid, containing 16 000 white cells/mm3 (97% polymorphs), protein 3.22 g/litre and glucose 0.1 mM although no organisms were seen on Gram stain. At this point the patient was transferred to a tertiary neurology centre, where a repeat CT after 3 days showed further fluid and oedema in the paranasal sinuses. Sinus washout was performed and nasal decongestants prescribed. Initial attempts at extubation led to repeated seizures. Blood tests performed included assessment of pituitary profile, which was unremarkable. Sedation was withdrawn 10 days after admission and the patient extubated; once awake it became clear that he was blind. The patient was pyrexial (38°C), agitated and hallucinating. It was thought that he had Anton's syndrome (cortical blindness and poor awareness of blindness). He was transferred to a neurology ward and a low-dose antipsychotic was started. The patient became more alert and orientated, and able to cooperate with ophthalmological examination, which established healthy optic discs, no intraocular abnormality, no papilloedema and no afferent papillary defect, supporting the diagnosis of cortical blindness. A repeat CT scan to investigate his continuing headache demonstrated loss of radiolucency of all the paranasal sinuses and the patient underwent functional endoscopic sinus surgery; this involved bilateral eithmoidectomy, sphenoidectomy and insertion of stents into both frontal sinuses. An audiogram demonstrated high frequency sensorineural deafness. The patient's condition improved and his eyesight partly recovered (visual acuity 6/60 right eye and 6/24 left eye). Further ophthalmology examination revealed bilateral disc pallor and optic atrophy was diagnosed. It was noticed that this patient's skin had become soft, pale and wrinkled and he was shaving less frequently than usual. On the basis of his skin appearance, a diagnosis of possible hypopituitarism was made, and pituitary hormone profile was assessed. This revealed panhypopituitarism and magnetic resonance imaging confirmed the presence of gross inflammation in the optic chiasm and around the pituitary, although the pituitary gland itself appeared intact (Figure 1). The patient was discharged home on pituitary replacement therapy with planned regular follow-up.

The incidence of sinusitis and the use of ultrasound in early diagnosis of sinusitis in patients with head injury

Sinusitis, complication of the head injury in critically ill patients, is an important cause of sepsis and may well be difficult to be diagnosed. In this study, we assayed the sensitivity and specificity of ultrasonography (USG) by comparing it with the computerized tomography (CT) and we determined the incidence of maxillary sinusitis with existing fluid in the maxillary sinuses.

The Role of Sinus Imaging in the Treatment of Chronic Cough in Adults

To determine the appropriate role and timing of sinus imaging studies in the evaluation and treatment of chronic cough. Prospective study of chronic cough. All patients underwent sinus imaging, the results of which identified prospectively the following: (1) fluid in sinuses, with or without opacification, and (2) mucosal thickening. Patients then were treated using an algorithm that sequentially addresses the etiologies of chronic cough. Patients whose sinus imaging studies had demonstrated fluid were treated initially for sinusitis, but mucosal abnormalities alone were not considered an indication to change the algorithm. After workup, relationships between abnormalities on sinus imaging studies and diagnoses were determined. University hospital pulmonary outpatient clinic. Thirty-six patients (31 women, 5 men; mean age, 58.4 years). Cough duration averaged 5.2 years (range, 4 weeks to 30 years). Diagnoses were made in 100% of patients, and cough resolved in 86%. Mucosal thickening correlated with sinusitis as a cause of cough in only 29% of cases. Mucosal thickening is not diagnostic of sinusitis as a cause of chronic cough; in most patients, cough will resolve without treatment for sinusitis. Given this lack of specificity, it is reasonable to delay sinus imaging until after efforts at treating rhinitis have failed and, in the absence of complaint or findings of postnasal drip, until after completion of evaluation for asthma. The principles of diagnosis and treatment of chronic cough remain simple: go sequentially from the most common to the least common cause; use tools that begin with the most available and least expensive and invasive modality; then move as needed to tools that are more expensive and invasive.

Fluid collection in the pericardial sinuses and recesses. Thin-section helical computed tomography observations and hypothesis.

This study describes the thin-section helical computed tomography (CT) appearance of near-water-density structures situated posterior to the pulmonary trunk and right main pulmonary artery, and to consider the implications of these CT images. Three-millimeter-thick helical CT scans of the mediastina of 133 patients were reviewed to determine the incidence and range of appearance of near-water-density structures situated posterior to the pulmonary trunk and right main pulmonary artery. Thin-section helical CT appearance was compared with that of fluid collection in the pericardial sinuses and recesses of patients with pericardial effusion, and with descriptions of the pericardial sinuses and recesses in the literature. Near-water-density structures showing varied appearance ranging from bands to mass-like densities were observed on thin-section helical CT images of 49 patients (37%) who had no obvious effusion in the pericardial cavity proper. The locations of the structures corresponded to the sites of recesses in the transverse and oblique sinuses, and their appearance was similar to that of fluid in the pericardial sinuses and recesses. Near-water-density structures situated posterior to the pulmonary trunk and right main pulmonary artery in patients without obvious pericardial effusion were concluded to be physiologic fluid collections in the recesses of the transverse and oblique sinuses.