Observation of high-energy neutrinos from the Galactic plane

The origin of high-energy cosmic rays, atomic nuclei that continuously impact Earth's atmosphere, is unknown. Because of deflection by interstellar magnetic fields, cosmic rays produced within the Milky Way arrive at Earth from random directions. However, cosmic rays interact with matter near their sources and during propagation, which produces high-energy neutrinos. We searched for neutrino emission using machine learning techniques applied to 10 years of data from the IceCube Neutrino Observatory. By comparing diffuse emission models to a background-only hypothesis, we identified neutrino emission from the Galactic plane at the 4.5σ level of significance. The signal is consistent with diffuse emission of neutrinos from the Milky Way but could also arise from a population of unresolved point sources.

Evidence for neutrino emission from the nearby active galaxy NGC 1068

A supermassive black hole, obscured by cosmic dust, powers the nearby active galaxy NGC 1068. Neutrinos, which rarely interact with matter, could provide information on the galaxy’s active core. We searched for neutrino emission from astrophysical objects using data recorded with the IceCube neutrino detector between 2011 and 2020. The positions of 110 known gamma-ray sources were individually searched for neutrino detections above atmospheric and cosmic backgrounds. We found that NGC 1068 has an excess of 79 − 20 + 22 neutrinos at tera–electron volt energies, with a global significance of 4.2σ, which we interpret as associated with the active galaxy. The flux of high-energy neutrinos that we measured from NGC 1068 is more than an order of magnitude higher than the upper limit on emissions of tera–electron volt gamma rays from this source.

Search for Unstable Sterile Neutrinos with the IceCube Neutrino Observatory

We present a search for an unstable sterile neutrino by looking for a resonant signal in eight years of atmospheric ν_{μ} data collected from 2011 to 2019 at the IceCube Neutrino Observatory. Both the (stable) three-neutrino and the 3+1 sterile neutrino models are disfavored relative to the unstable sterile neutrino model, though with p values of 2.8% and 0.81%, respectively, we do not observe evidence for 3+1 neutrinos with neutrino decay. The best-fit parameters for the sterile neutrino with decay model from this study are Δm_{41}^{2}=6.7_{-2.5}^{+3.9}  eV^{2}, sin^{2}2θ_{24}=0.33_{-0.17}^{+0.20}, and g^{2}=2.5π±1.5π, where g is the decay-mediating coupling. The preferred regions of the 3+1+decay model from short-baseline oscillation searches are excluded at 90% C.L.

Strong Constraints on Neutrino Nonstandard Interactions from TeV-Scale ν_{μ} Disappearance at IceCube

We report a search for nonstandard neutrino interactions (NSI) using eight years of TeV-scale atmospheric muon neutrino data from the IceCube Neutrino Observatory. By reconstructing incident energies and zenith angles for atmospheric neutrino events, this analysis presents unified confidence intervals for the NSI parameter ε_{μτ}. The best-fit value is consistent with no NSI at a p value of 25.2%. With a 90% confidence interval of -0.0041≤ε_{μτ}≤0.0031 along the real axis and similar strength in the complex plane, this result is the strongest constraint on any NSI parameter from any oscillation channel to date.

Search for Relativistic Magnetic Monopoles with Eight Years of IceCube Data

We present an all-sky 90% confidence level upper limit on the cosmic flux of relativistic magnetic monopoles using 2886 days of IceCube data. The analysis was optimized for monopole speeds between 0.750c and 0.995c, without any explicit restriction on the monopole mass. We constrain the flux of relativistic cosmic magnetic monopoles to a level below 2.0×10^{-19}  cm^{-2} s^{-1} sr^{-1} over the majority of the targeted speed range. This result constitutes the most strict upper limit to date for magnetic monopoles with β≳0.8 and up to β∼0.995 and fills the gap between existing limits on the cosmic flux of nonrelativistic and ultrarelativistic magnetic monopoles.

eV-Scale Sterile Neutrino Search Using Eight Years of Atmospheric Muon Neutrino Data from the IceCube Neutrino Observatory

The results of a 3+1 sterile neutrino search using eight years of data from the IceCube Neutrino Observatory are presented. A total of 305 735 muon neutrino events are analyzed in reconstructed energy-zenith space to test for signatures of a matter-enhanced oscillation that would occur given a sterile neutrino state with a mass-squared differences between 0.01 and 100  eV^{2}. The best-fit point is found to be at sin^{2}(2θ_{24})=0.10 and Δm_{41}^{2}=4.5  eV^{2}, which is consistent with the no sterile neutrino hypothesis with a p value of 8.0%.

Characteristics of the Diffuse Astrophysical Electron and Tau Neutrino Flux with Six Years of IceCube High Energy Cascade Data

We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of ϕ_{astro}=1.66_{-0.27}^{+0.25} at E_{0}=100  TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices γ≤2.28 at ≥3σ significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below ∼100  TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value ≥0.06). The sizable and smooth flux measured below ∼100  TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays.

Time-Integrated Neutrino Source Searches with 10 Years of IceCube Data

This Letter presents the results from pointlike neutrino source searches using ten years of IceCube data collected between April 6, 2008 and July 10, 2018. We evaluate the significance of an astrophysical signal from a pointlike source looking for an excess of clustered neutrino events with energies typically above ∼1  TeV among the background of atmospheric muons and neutrinos. We perform a full-sky scan, a search within a selected source catalog, a catalog population study, and three stacked Galactic catalog searches. The most significant point in the northern hemisphere from scanning the sky is coincident with the Seyfert II galaxy NGC 1068, which was included in the source catalog search. The excess at the coordinates of NGC 1068 is inconsistent with background expectations at the level of 2.9σ after accounting for statistical trials from the entire catalog. The combination of this result along with excesses observed at the coordinates of three other sources, including TXS 0506+056, suggests that, collectively, correlations with sources in the northern catalog are inconsistent with background at 3.3σ significance. The southern catalog is consistent with background. These results, all based on searches for a cumulative neutrino signal integrated over the 10 years of available data, motivate further study of these and similar sources, including time-dependent analyses, multimessenger correlations, and the possibility of stronger evidence with coming upgrades to the detector.

Constraints on Minute-Scale Transient Astrophysical Neutrino Sources

High-energy neutrino emission has been predicted for several short-lived astrophysical transients including gamma-ray bursts (GRBs), core-collapse supernovae with choked jets, and neutron star mergers. IceCube's optical and x-ray follow-up program searches for such transient sources by looking for two or more muon neutrino candidates in directional coincidence and arriving within 100 s. The measured rate of neutrino alerts is consistent with the expected rate of chance coincidences of atmospheric background events and no likely electromagnetic counterparts have been identified in Swift follow-up observations. Here, we calculate generic bounds on the neutrino flux of short-lived transient sources. Assuming an E^{-2.5} neutrino spectrum, we find that the neutrino flux of rare sources, like long gamma-ray bursts, is constrained to <5% of the detected astrophysical flux and the energy released in neutrinos (100 GeV to 10 PeV) by a median bright GRB-like source is <10^{52.5}  erg. For a harder E^{-2.13} neutrino spectrum up to 30% of the flux could be produced by GRBs and the allowed median source energy is <10^{52}  erg. A hypothetical population of transient sources has to be more common than 10^{-5}  Mpc^{-3}  yr^{-1} (5×10^{-8}  Mpc^{-3}  yr^{-1} for the E^{-2.13} spectrum) to account for the complete astrophysical neutrino flux.

Search for neutrinos from decaying dark matter with IceCube: IceCube Collaboration

With the observation of high-energy astrophysical neutrinos by the IceCube Neutrino Observatory, interest has risen in models of PeV-mass decaying dark matter particles to explain the observed flux. We present two dedicated experimental analyses to test this hypothesis. One analysis uses 6 years of IceCube data focusing on muon neutrino 'track' events from the Northern Hemisphere, while the second analysis uses 2 years of 'cascade' events from the full sky. Known background components and the hypothetical flux from unstable dark matter are fitted to the experimental data. Since no significant excess is observed in either analysis, lower limits on the lifetime of dark matter particles are derived: we obtain the strongest constraint to date, excluding lifetimes shorter than10 28 s at 90% CL for dark matter masses above 10 TeV .

Response to Alpha-Interferon Treatment of the Congenital Dyserythropoietic Anemia type I in Two Sicilian Beta Thalassemia Carriers

Congenital dyserythropoietic anemia type I (CDAI) is an autosomal recessive inherited haematological disorder associated with moderate-to-severe anemia characterized by ineffective erythropoiesis with distinct morphological abnormalities in erythroid precursors. We present two case of congenital dyserythropoietic anemia type I in two Sicilian patients heterozygous for β⁰ 39 globin gene cod 39 C > T with marked bone marrow abnormalities, responding to treatment with alpha interferon. The diagnosis was established using routine haematological and biochemical test, light and electron microscopy; molecular analysis of the CDAN1 gene associated to the CDAI disease was performed. The response to the treatment was monitored using the hemoglobin levels, the red cell count, the reticulocyte count and the transfusional requirement. This report points out the usefulness of the treatment with interferon alpha in two Sicilian beta thalassemia carriers, in which the therapy was well tolerated without producing any side effects; in these patients the transfusion requirements after the initiation of interferon therapy decreased.

New Codanin-1 Gene Mutations in a Italian Patient with Congenital Dyserythropoietic Anemia Type I and Heterozygous Beta-Thalassemia

Congenital dyserythropoietic anemia type I is an autosomal recessive disorder associated with macrocytic anemia, ineffective erythropoiesis, iron overloading and characterized by abnormal chromatin ultrastructure in erythroblasts such as internuclear chromatin bridges, spongy heterochromatin and invagination of the nuclear membrane. A 58-year-old Causasian man with chronic hemolytic anemia, heterozygous for β (+) -globin IVS1, nt110 G>A mutation (causing abnormal alpha:beta globin chain ratio) showed clinical, laboratory and hematological features suggesting diagnosis of CDA1. Sequence analysis of CDA-related genes revealed compound heterozygosity for two novel mutations in the CDAN1 gene: a frameshift mutation 3367 del 4 (TTAG) in exon 25 and a missense mutation c.1811 G>T in exon 11 causing an aminoacid change from glycine to valine at codon 565 (G565V). One of the propositus' brothers showed the same gene mutations. As the CDA1 can mimic thalassemia, a frequent misdiagnosis is possible especially in countries where the prevalence of thalassemia is high. A strong clinical suspicion in patients who do not reveal a clear genetic basis for presumed thalassemia may help clinch the correct diagnosis.

Interventional techniques in vascular trauma

This article addresses in detail the newer role for interventional angiography, including diagnosis and newer angioembolization techniques used to control bleeding and to deal with complications of vascular injuries.

Angiographic findings in pelvic fractures

Pelvic fractures are high energy injuries indicative of significant trauma. Hypotension and significant blood loss is common in skeletally unstable pelvic fractures. Potential sites of intrapelvic bleeding include fractured bone edges, venous injuries and/or arterial vascular injuries. In an attempt to define the relationship of fracture pattern to arterial injury, a specific subset of 39 patients with pelvic fractures who underwent angiography for hemodynamic instability or ongoing blood loss were reviewed retrospectively. In 35 patients with definable arterial injuries, 20 (57%) had multiple bleeding sites. Posterior arterial bleeding (internal iliac or its posterior branches) was statistically more common in patients with unstable posterior pelvic fractures, and anterior arterial bleeding (pudendal or obturator) was more common in patients with lateral compression injuries. The pudendal artery was the most commonly injured vessel in this series. The superior gluteal artery was the most commonly injured vessel associated with posterior pelvic fractures. There was no correlation between fracture pattern and survival. The injury severity score however, did indirectly correlate to survival. In addition, the presence of hypotension (systolic blood pressure < or = 90) at the time of arrival to the trauma center was found to significantly increase mortality.

The management of vascular injuries of the extremity associated with civilian firearms

A penetrating extremity trauma registry was created to prospectively study the physical findings, use of arteriography, nonoperative management with embolization or observation and operation in the management of vascular injuries. During a recent ten month period, 228 patients with 320 injuries of the extremity secondary to firearms were admitted to the Trauma Service. Twenty-four percent of the patients had more than one injury, and there were six perioperative deaths related to associated injuries. Fifty-one patients had 50 arterial and 17 venous injuries. Limb salvage was 100 percent. Twenty-two patients with obvious arterial injuries were taken directly to the operating room without arteriography. Arteriography was performed immediately after admission in 41 patients and the findings were positive in 46.4 percent of the patients; nine required operation. Arteriography was performed for injuries in proximity to a major vessel as the indication in 153 injuries and revealed seven arterial injuries (4.6 percent). Three patients underwent operation. Five patients with arterial injuries had successful embolization during the initial arteriography and five patients with intimal injuries were observed, four healed and one patient was lost to follow-up evaluation. Operative repair of arterial injuries included the use of saphenous vein (21 patients), prosthetic grafts (seven patients) and ligations (four patients). Seventeen venous injuries were either repaired (eight patients) or ligated (nine patients). In the patients undergoing operative repairs, 68.7 percent had fasciotomies performed. The excellent results in the current study (no amputations with 51 survivors of arterial injuries) were obtained by a multidisciplinary approach, involving selective arteriography to avoid unnecessary operation and operative repair in those with extensive vascular injuries. The use of arteriography for proximity characterized a few vascular injuries requiring operation or observation. It should serve as the standard for evaluating noninvasive diagnostic studies and for studying the natural history of asymptomatic injuries.

The management of gunshot wounds to the face

Treatment principles for penetrating neck trauma are well described yet few exist for facial injuries. To help delineate these issues, we viewed our recent experience with gunshot wounds to the face. Since 1986 we have treated 100 patients with such injuries. Their mean age was 28.9 years (range, 12-77 years). There were 89 male patients and 11 female patients. Ninety-six patients were considered stable on initial examination. Yet 35 patients required urgent airway control in the ED; only two needed a surgical airway. Emergency angiography was performed in 37 patients; 19 vascular injuries were identified. Eleven required therapy for vascular injuries, five by neck exploration and six by embolization. In 15 patients the trajectory suggested an intracranial injury, i.e., across the base of the skull. Although 14 of 16 patients were awake and alert at examination, head CT scans demonstrated serious intracranial pathologic processes in 9 patients. Sixty-seven patients sustained bony injury, 19 patients a significant nonvascular soft-tissue injury, and 38 patients a significant neurologic injury (26 peripheral, one spinal and 20 cerebral injuries). Ultimately, 44% of all patients required some surgical treatment and 25% had a complication from their injury. Six patients died, three of CNS injury, one of exsanguination, and two of sepsis. The bony, soft tissue, nervous, and vascular anatomy make the management of gunshot wounds to the face challenging. Although initially stable, many patients require early airway control and urgent work-up for vascular and intracranial injuries. Early subspecialty input is helpful in delineating the often complex injury pattern and planning an optimal management strategy.

Packing and re-exploration for patients with nonhepatic injuries

We retrospectively reviewed the clinical records of 11 patients admitted to the trauma service at Kings County Hospital who underwent packing and temporary closure for severe nonhepatic injuries. The mean ISS was 37 and the mean Abdominal Trauma Index value was 48. Operative findings included 17 major vascular injuries. Although the mean blood pressure was 105 mm Hg during the procedure, the patients required an average of 17 units of blood and all were acidotic, hypothermic, and coagulopathic. Acidosis persisted in all patients and the mean base excess was -13 at closure. A conscious decision was made to terminate the procedure when surgical bleeding was controlled. Patients were resuscitated and warmed in the ICU and returned to the operating room within 48 hours. Seven of the 11 patients survived. Of the eight patients who survived to return to the operating room, all required gastrointestinal procedures at re-exploration. This preliminary experience supports packing to control coagulopathic bleeding, use of temporary abdominal closure, and further ICU resuscitation with a planned second laparotomy for definitive management of gastrointestinal injuries in patients with severe nonhepatic injuries.

Percutaneous antegrade ureteral stenting as an adjunct for treatment of complicated ureteral injuries

We report our use of percutaneous antegrade ureteral stenting (PAUS) as an adjunct for the management of dehisced ureteral repairs and delayed-presentation ureteral injuries secondary to penetrating trauma. This procedure was performed in treating six patients with ureteral injuries. Four patients had dehiscence of a lacerated ureter that had been primarily repaired. Two other patients had ureteral contusions that subsequently became full-thickness disruptions postoperatively. One of these patients developed a pancreaticoureteral fistula. The sepsis resolved in all six patients and in five of the six patients the ureteral disruption healed within 2 months after PAUS without operative intervention. In one patient the ureter healed with stricture, necessitating ureteral reanastomosis. All urinomas resolved with percutaneous drainage. The PAUS technique was used to successfully treat four dehisced ureteral repairs and was the primary method used to successfully treat two disrupted ureteral contusions that were associated with multiple collections and fistulas. These techniques can be utilized for complex ureteral injuries associated with pancreatic leaks, colon or duodenal injuries, and multiple abscesses.

Reversible increased technetium-99m-HMPAO cerebral cortical activity: a scintigraphic reflection of luxuriant hyperperfusion

A hemiparetic and aphasic patient, 3 days after acute traumatic transection of the left internal carotid artery requiring life-saving total embolic occlusion, revealed ipsilateral increased peripheral hemispheric 99mTc-HMPAO activity. Ten days postocclusion, HMPAO peripheral cortical flow normalized as hemiparesis and aphasia significantly cleared. The initial lateralized HMPAO hyperactivity pattern may reflect reactive hyperemia, a sign previously identified by contrast angiography and often associated with a better prognosis in evolving CVA. Evanescent peripheral cerebral hyperemia may represent beneficial cortical collateralization of the periinfarct area of a deeper lacunar (white matter) CVA.

Role of diagnostic techniques in the initial evaluation of stab wounds to the anterior abdomen, back, and flank

Despite the widespread availability of firearms, stab wounds to the abdomen, back, and flank continue to account for a significant number of injuries. The proper sequencing of diagnostic modalities in this patient group is constantly undergoing change. We report our experience with these injuries and present a new algorithm for the use of currently available diagnostic procedures. In 1987, 162 patients were seen, 103 with anterior abdominal wounds and 59 with back and flank wounds. Patients with shock, peritonitis, and evisceration were resuscitated and explored. The remainder of the cohort underwent tap and lavage, and patients with a negative study were observed. Patients with back and flank wounds underwent contrast enhanced computerized tomographic enemas (CECTE). Seventeen patients underwent immediate exploration and 108 of the 162 patients were spared exploration. Fifty-four patients were explored with six negative laparotomies. Of the 126 taps and lavages, the false positive rate was zero, and only one patient had a false negative study. Of the 47 CECTE studies, only three were interpreted as an indication for angiography which proved negative, and all patients were safely observed. The overall mortality was 4.3%, including three patients without vital signs on admission and four who expired intraoperatively due to irreversible shock. We concluded that this algorithm can be safely applied to patients with these injuries with a high degree of specificity and sensitivity.

Histamine blockade and cardiovascular changes following heparin administration during cardiac surgery

Large doses of heparin given as a bolus may produce hypotension; however, conflicting reports exist about the mechanisms involved. This study was undertaken to determine the role of histamine in beef lung heparin-induced hypotension and the efficacy of histamine-receptor blockade in attenuating this undesirable side effect in patients undergoing cardiac surgery. Two hundred patients with good ventricular function were studied after they were randomized into four equal groups. Group I (control) received no histamine-receptor blockade, group II received 1 mg/kg of diphenhydramine 30 minutes prior to heparin administration, group III received 5 mg/kg of cimetidine 4 hours and again 30 minutes before heparin administration, and group IV received 1 mg/kg of diphenhydramine 30 minutes prior to heparin administration and 5 mg/kg of cimetidine 4 hours and 30 minutes before heparin administration. Hemodynamic variables, plasma histamine, and ionized calcium levels were measured before and after heparin administration. Significant hypotension occurred in group I patients after heparin administration. Mean arterial pressure decreased from 95 +/- 5 to 67 +/- 1.5 mm Hg (P less than 0.005) after 1 minute and to 85 +/- 2 mm Hg (P less than 0.05) at 4 minutes. Those changes were significantly greater than in group II (P less than 0.025) and Group IV (P less than 0.005) patients, in whom no significant hypotension was found. In group III, mean arterial pressure decreased from 92 +/- 3 to 75 +/- 1 mm Hg (P less than 0.05) after 1 minute and returned toward baseline values after 4 minutes. Histamine levels increased significantly in all groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Exposure of the internal carotid artery near the skull base: the posterolateral anatomic approach

Internal carotid injuries in zone III near the base of the skull are technically the most challenging of the carotid injuries. Diagnostic angiography is important to evaluate the exact site and extent of injury and the presence or absence of prograde flow in the injured segment. Vascular repair in this area is highly dependent on the adequacy of surgical exposure. Previous approaches have emphasized displacement of the mandible either by subluxation or mandibulotomy. Problems related to mandibulotomy, such as intraoral contamination, infection, and nonunion, are potential complications of this approach to the high carotid artery. In addition, it does not give adequate exposure of the internal carotid artery at the critical area, near the base of the skull. Experience gained from the extended radical neck dissection exposing the internal carotid artery up to the skull base has demonstrated that a posterolateral anatomic approach can provide superior exposure of the high carotid artery with lower morbidity and shortened operative time. This surgical approach involves cutting the sternomastoid muscle close to the mastoid and dissecting all the tissues away from the surface of the mastoid. Dividing the posterior belly of the digastric and styloid group of muscles assists in exposure of the internal carotid artery. Rarely, dissection of the facial nerve and removal of the tail of parotid add additional access to this area. This article describes the stepwise anatomic approach to the internal carotid artery near the base of the skull.

Tinnitus originating from an abnormal jugular bulb: treatment by jugular vein ligation

Tinnitus and hearing loss can occur in patients with a high-riding abnormal jugular bulb. Jugular vein ligation in selected patients can cure tinnitus and reverse hearing loss. A 39-year-old woman reported a 4-year history of right-sided tinnitus of increasing intensity associated with a mild hearing loss. Extensive evaluation revealed only an enlarged right jugular bulb with dehiscence of the normal petrous bony septum between the bulb and the middle ear. The patient underwent ligation of the right internal jugular vein and noted immediate cessation of tinnitus and the return of normal hearing. Review of the literature suggests that jugular vein ligation is appropriate in selected cases of venous tinnitus.

Vertebral artery injury--diagnosis and management

The literature on vascular trauma contains little information on the management of vertebral artery injuries. We have reviewed our experience consisting of 23 patients with vertebral artery injuries caused by 19 gunshot wounds, two stab wounds, one shotgun wound, and one blunt injury. Twelve patients sustained unilateral vertebral artery thrombosis, seven patients had vertebral AV fistulae (three jugular vein, four vertebral vein) and four patients sustained mural injury without thrombosis. Six patients (26.1%) developed major neurologic deficits of which five could be directly attributed to CNS missile injury. One patient had transient vertebrobasilar ischemia on the basis of a vertebral AV fistula. Four of the seven vertebral AV fistulae were managed solely by therapeutic embolization and two patients early in the series underwent surgical management alone. One patient had therapeutic embolization of the proximal vertebral artery and operative distal vertebral artery ligation for an AV fistula. The four patients who died (17.4%) did so as a direct result of their CNS missile injury. We conclude that: 1) unilateral vertebral artery occlusion seldom results in a neurologic deficit if there is a normal contralateral vertebral artery and PICA (posterior inferior cerebellar artery) blood supply is preserved; 2) accurate assessment of a vertebral artery injury requires contralateral vertebral arteriogram; 3) management of vertebral artery injury is simplified by proximal, and if possible distal, therapeutic embolization; 4) an anterior approach to the C1-2 vertebral artery is a satisfactory method of obtaining distal surgical control, obviating the need to unroof the bony canal of the vertebral artery; 5) angiography is necessary in penetrating neck trauma to identify occult vascular injuries.

Late CT detection of gas in an aortic graft: a normal postoperative finding

Presence of gas in the prosthetic graft bed does not necessarily represent infection, but may rather be indicative of the presence of benign gas. The diagnostic and therapeutic implications of this finding are discussed.