Cerebral venous sinus thrombosis cases detected in on-call CT venographies in Sweden, 2019-2022.

No well-established criteria exist for assessing the risk of cerebral venous sinus thrombosis (CVST). Here, we sought to gain an understanding of CVST cases and associated risk factors, based on the rates of emergency CT venographies (CTVs) performed after hours. Furthermore, we aimed to assess possible correlations between CVST rates and COVID-19, including at the start of the COVID-19 vaccination campaign. We collected reports of emergency CTVs performed after hours at 56 Swedish hospitals between 1/1/2019 and 12/31/2022, and divided them into five groups: (I) from 1/1/2019 to 1/31/2020, before the emergence of COVID-19 cases in Sweden; (II) from 2/1/2020 to 12/26/2020, after the emergence of COVID-19 but before vaccination rollout; (III) from 12/27/2020 to 7/28/2021, from the start of the COVID-19 vaccination campaign until 50% of the adult population in Sweden had been vaccinated; (IV) from 7/29/2021 to 2/1/2022, from when 50% of the adult population was vaccinated until restrictions were lifted; and (V) from 2/2/2022 to 12/31/2022, after restriction measures were suspended. For all included patients, we collected information on demographics and clinical history, including pregnancy, recent partum, and use of oral contraceptives or post-menopausal hormone replacement therapy. In total, we collected 430 reports (92% female, 8% male). The CVST positivity rate was 22.2% in men vs. 2.3% in women. None of the pregnant (n = 49) or postpartum (n = 12) women had CVST positivity. The frequency of CTV examinations was lowest in group 2; during this period, the average time between patients being imaged was 7 days. The frequency of CTV examinations was highest in group IV; during this period, a patient underwent this type of scan every 1.5 days, on average. The frequency of CVST-positive scans was lowest in group II; during this period, a positive case was found every 66 days, on average. The frequency of CVST-positive scans was highest in group IV; during this period, a positive case was found every 62 days, on average, and no statistical difference with respect to group II was observed. Pregnancy and recent partum were not significant risk factors for CVST. The elevated CVST positivity rate observed during the height of the COVID-19 pandemic suggested that patients with less likelihood for positive CVST had fewer emergency visits. The positivity rate did not increase with the start of the COVID-19 pandemic or the rollout of COVID-19 vaccination.

Impact of COVID-19 on the incidence of CT-diagnosed appendicitis and its complications in the UK and Sweden.

AIM: To compare the number of appendicitis cases and its complications, during the first months of the COVID-19 pandemic in Sweden and the UK and the corresponding time period in 2019. METHOD: Reports of emergency abdominopelvic CT performed at 56 Swedish hospitals and 38 British hospitals between April and July 2020 and a corresponding control cohort from 2019 were reviewed. Two radiologists and two surgeons blinded to the date of cohorts analyzed all reports for diagnosis of appendicitis, perforation, and abscess. A random selection of cases was chosen for the measurement of inter-rater agreement. RESULT: Both in Sweden (6111) and the UK (5591) fewer, abdominopelvic CT scans were done in 2020 compared to 2019 (6433 and 7223, respectively); p < 0.001. In the UK, the number of appendicitis was 36% lower in April-June 2020 compared to 2019 but not in Sweden. Among the appendicitis cases, there was a higher number of perforations and abscesses in 2020, in Sweden. In the UK, the number of perforations and abscesses were initially lower (April-June 2020) but increased in July 2020. There was a substantial inter-rater agreement for the diagnosis of perforations and abscess formations (K = 0.64 and 0.77). CONCLUSION: In Sweden, the number of appendicitis was not different between 2019 and 2020; however, there was an increase of complications. In the UK, there was a significant decrease of cases in 2020. The prevalence of complications was lower initially but increased in July. These findings suggest variability in delay in diagnosis of appendicitis depending on the country and time frame studied.

Analysis of aortic wall stress and rupture risk in patients with abdominal aortic aneurysm with a gender perspective.

OBJECTIVE: The most commonly used predictor of rupture of an abdominal aortic aneurysm (AAA) is the diameter; however, this does not estimate the true risk for each patient. Why women with AAAs have an increased growth rate, weaker aortic wall, and increased risk for rupture is yet unclear. It is likely that geometrical and biomechanical properties contribute to found gender differences. Several studies have shown that peak wall stress (PWS) and peak wall rupture risk (PWRR), predicted by a finite element (FE) analysis of AAAs derived from computed tomography (CT), is a better predictor of rupture than maximum diameter. The purpose of this study was to investigate if women with AAAs have an increased PWS and PWRR using an FE model compared to men. METHOD: Fifteen men and 15 women (AAAs 4-6 cm) were included. AAA geometry was derived from CT scans, and PWS and PWRR were estimated using the FE method. Comparisons were made by t test and Mann-Whitney test. RESULTS: Mean age (women 73 years old vs men 71 years old) and mean AAA diameter was similar (49.7 mm vs 50.1 mm) for women and men. PWS did not differ for women 184 and men 198 kPa. PWRR was 0.54 (0.28-0.85) for women and 0.43 (0.24-0.66) for men, P = .06. CONCLUSION: This is the first analysis of stress and strength of the aneurysm wall with a gender perspective. The reported higher rupture risk for women has previously not been tested with geometrical and biomechanical properties. PWS did not differ, but the PWRR was slightly higher in women. However, the difference did not reach statistical significance, probably due to the small sample size. In summary, the results in the present study suggest that differences in biomechanical properties could be a contributing explanation for the higher rupture risk reported for female patients with AAAs.

Imaging the intraluminal thrombus of abdominal aortic aneurysms: techniques, findings, and clinical implications.

Intraluminal thrombus (ILT) is known to influence the natural history of abdominal aortic aneurysms, and its effect on the arterial wall may predict the risks of rupture. The main features of ILT believed to be associated with aneurysm growth and increased rupture risk are size; presence of fissures, dissections, or calcifications in the ILT; and inhomogeneity in its internal structure. Modern imaging allows for detailed depiction of the ILT. This review describes the techniques, findings, clinical implications, advantages, and disadvantages of imaging the ILT by ultrasound, contrast-enhanced computed tomography, and magnetic resonance imaging.

Effects of outsourcing magnetic resonance examinations from a public university hospital to a private agent.

BACKGROUND: Sometimes the measures taken to make a radiology department more effective, such as prioritizing the workload and keeping equipment running for as many hours as staffing permits, are not enough. In such cases, outsourcing radiological examinations is a potential solution for reducing waiting times. PURPOSE: To investigate differences in waiting time, quality and costs between magnetic resonance (MR) examinations performed in a university hospital and examinations outsourced to private service. MATERIAL AND METHODS: We retrospectively selected a group of consecutive, outsourced MR examinations (n=97) and a control group of in-house MR examinations, matched for type of examination. In each group there were referrals that had a specified preferred timeframe for completion. We measured the percentage of cases in which this timeframe was met and if it was not met, how many days exceeded the preferred time. In referrals without a specified preferred timeframe, we also calculated the waiting time. Quality standards were measured by the percentage of examinations that had to be re-done and re-assessed. Finally, we calculated the cumulative costs, taking into account the costs for re-doing and re-assessing examinations. RESULTS: There was no statistically significant difference between the groups, in either the number of examinations that were not performed within the preferred time or the number of days that exceeded the preferred timeframe. For referrals without a preferred timeframe, the waiting time was shorter for outsourced examinations than those not outsourced. There were no differences in the number of examinations that had to be re-done, but more examinations needed to be re-assessed in the outsourced group than in the in-house group. The calculated costs for outsourced examinations were lower than the costs for internally performed examinations. CONCLUSION: Outsourcing magnetic resonance examinations may be an effective way of reducing a radiology department's workload. Ways in which to reduce the additional costs incurred for re-assessment of outsourced examinations must be investigated further.

Accuracy of low-dose chest CT in intensive care patients.

In this prospective study, we set out to determine the accuracy of low-dose computerized tomography (LDCT) of the chest in intensive care patients. Fifteen adult intensive care patients were examined with a standard-dose CT protocol (average radiation dose = 6.7 mSv), chosen as the reference standard, followed by a non-contrast-enhanced LDCT protocol (average radiation dose = 0.59 mSv). Each examination was then read by two separate groups of radiologists blinded to both the purpose and the protocol of the study. In the small group examined, the results showed 100% accuracy in the diagnosis of pneumomediastinum, pericardial effusion, and pleural effusion, and 90% accuracy in the diagnosis of pneumothorax and consolidation. There were no false-positive findings, and the few false-negative findings were unlikely to lead to any clinical interventions. Our examination protocol, while providing a tenfold reduction of the radiation dose, nevertheless remained accurate enough for resolving certain clinical questions common in the intensive care patient. Thus, we suggest that protocols aimed at reducing the radiation dose in chest CT could be applied to the intensive care patient for resolving some specific questions, without compromising the diagnostic yield of the examinations.

The accuracy of focused abdominal CT in patients presenting to the emergency department.

Focused computed tomography(CT) examination (FCT) is CT limited to a specific abdominal area in an attempt to reduce radiation exposure. We wanted to evaluate FCT on the basis of information from the request form and thus reduce radiation dose to the patient without missing relevant findings. We retrospectively analyzed 189 consecutive acute abdominal CT, dividing the findings as localized in the upper or lower abdomen. Another researcher blindly determined where the CT should be focused to, based only on information provided in the request form. The sensitivity and specificity of FCT in patients with symptoms from only upper abdomen was 100%. Sensitivity, specificity, and accuracy of FCT in patients with symptom from only lower abdomen were 79%, 100%, and 92%, respectively. Our study suggests that among patients with symptoms from the lower abdomen, not examining the upper abdomen would lead to missing relevant findings.

Bleeding into the intraluminal thrombus in abdominal aortic aneurysms is associated with rupture.

OBJECTIVE: The aim of this study was to determine signs of bleeding in the intraluminal thrombus and the site of rupture using multislice computed tomography (CT) imaging in patients with abdominal aortic aneurysms (AAA). METHODS: We analyzed CT images of 42 patients with ruptured infrarenal AAA in two hospitals in Stockholm, Sweden during a 3-year period. A "crescent sign" or localized areas with higher attenuation in the thrombus were interpreted as signs of bleeding in the thrombus. A localized area of hyperattenuation did not have the typical crescent shape and was distinguished from calcifications in the thrombus. We measured the attenuation in Hounsfield units in the intraluminal thrombus using CT software to quantify the presence of blood in the thrombus. As controls, we analyzed 36 patients with intact AAA and a comparable aneurysm diameter and age. RESULTS: The crescent sign was more frequent in the ruptured group (38% vs 14%, P = .02), but there was no significant difference in the presence of localized areas of hyperattenuation in the two groups. The attenuation in the thrombus was significantly higher in patients with rupture than in those with intact aneurysms (P = .02). The site of rupture could be localized in 29/42 patients. Ruptures occurred both through the thrombus-covered and the thrombus free wall. In 45% of the patients, the rupture site was localized in the left lateral wall, in 24% in the anterior wall, in 24% in the right lateral wall, but only in 7% in the posterior wall. CONCLUSION: The site of rupture could be identified in a majority of cases of AAA with routine multislice CT. This study demonstrates an association between the presence of blood in the thrombus as suggested by higher attenuation levels and a crescent sign and AAA rupture. If these findings also predict AAA rupture, remains to be established.

Small skin burn injury reduces cardiac tolerance to ischemia via a tumor necrosis factor alpha-dependent pathway.

BACKGROUND: Large burns cause systemic inflammation and myocardial depression. We hypothesized that small burns affect cardiac tolerance to ischemia, and that tumor necrosis factor alpha (TNFalpha) signaling through endothelin-1 (ET) and nuclear factor kappa B (NF kappaB) are associated. METHODS: Mice were randomly assigned to four groups: burn (caused by boiling water on <2% of the body surface area), sham, burn+etanercept (TNFalpha blocker) treatment and sham+etanercept treatment. Twenty-four hours later, hearts were isolated and subjected to global ischemia followed by reperfusion. Additional hearts and burned skin lesions were sampled to evaluate expression of TNFalpha (immunoblotting) and endothelin-1 (radioimmunoassay). A NF kappaB-luciferase reporter mouse was used to evaluate NF kappaB activation. RESULTS: Baseline cardiac function before ischemia (BI) was only negligibly influenced by burn or etanercept, but was reduced by burn+etanercept. Burn markedly impaired post-ischemic left ventricular function and increased infarct size in comparison with sham-treated mice. Cardiac, but nut cutaneous, expression of TNFalpha was increased in burned mice, while cardiac NF kappaB and endothelin-1 were not influenced. TNFalpha blockade reduced the detrimental effects of burn on cardiac tolerance to ischemia. CONCLUSIONS: Small cutaneous burns, that did not influence baseline heart function, impaired the tolerance to ischemia. This effect may be mediated through TNFalpha, but does not involve signaling through NF kappaB or endothelin-1.

Microcirculation in healing and healthy Achilles tendon assessed with invasive laser doppler flowmetry.

INTRODUCTION: Achilles tendon (AT) rupture exhibits a prolonged healing process with varying clinical outcome. Reduced blood flow to the AT has been considered an underlying factor to AT rupture (ATR) and impaired healing. In vivo measurements using laser Doppler flowmetry (LDF) may be a viable method to assess blood flow in healthy and healing AT. METHODS: 29 persons were included in the study; 9 being ATR patients and 20 healthy subjects without any prior symptoms from the AT. Invasive LDF was used to determine the post-occlusive reactive hyperemia (PORH) in the paratenon after 15 minutes of occlusion of the lower extremities. ATR patients were examined two weeks post-operatively. RESULTS: LDF-assessments demonstrated a significantly different (p < 0.001) PORH response in the healing- versus intact- and control AT. In the healing AT, a slow, flattened PORH was observed compared to a fast, high peak PORH in intact, healthy AT. CONCLUSION: in vivo LDF appears to be a feasible method to assess alterations in blood flow in healing and intact AT. The healing ATs capability to react to an ischemic period is clearly impaired, which may be due to the trauma at injury and/or surgery or degenerative changes in the tendon.

Intraperitoneal injection induces a delayed preconditioning-like effect in mice.

We hypothesized that intraperitoneal injections of anaesthetics or fluid per se might evoke a delayed preconditioning-like response in mice hearts isolated and Langendorff perfused 24 h later. To test this, mice were given opioid anaesthesia by intraperitoneal injections or sham treated and the hearts were harvested and subjected to global ischaemia and reperfusion 24 h later in series 1. In series 2, mice were subjected to intraperitoneal injection of Ringer, sham needle prick procedure, or no intervention 24 h before heart isolation. In series 3, intraperitoneal Ringer injection 24 h earlier was compared with the effects of classic preconditioning or no pretreatment of the isolated heart or no treatment. Heart function was measured in all series. At the end of reperfusion, hearts in series 1 and 2 were frozen and infarct size was estimated by triphenyltetrazolium chloride solution. In series 3, separate hearts were frozen for immunoblotting to detect phosphorylation of mitogen-activated protein (MAP) kinases. Cardiac activation of nuclear factor kappa B (NFkappaB) was measured using a NFkappaB luciferase firefly reporter mouse. The ischaemia-induced impairment of left ventricular function was attenuated by opioid anaesthesia injected 24 h earlier, which also reduced infarct size. Injection of fluid, but not the sham needle prick procedure, reduced infarct size. The functional protection afforded by classic preconditioning and Ringer pretreatment was comparable. Neither cardiac MAP kinases nor NFkappaB were influenced by the interventions. In conclusion, this study demonstrates a delayed preconditioning-like effect of the heart caused by intraperitoneal administration of opioid anaesthetics and of fluid only in the mouse. The mechanism of protection remains to be determined.

Myocardial protection by remote preconditioning: the role of nuclear factor kappa-B p105 and inducible nitric oxide synthase.

OBJECTIVE: Adaptation to ischemia by brief episodes of ischemia and reperfusion (preconditioning) of the heart protects the heart against sustained ischemia, where the transcription factor nuclear factor kappa-B (NFkappaB) appears crucial for the protection. Preconditioning of the heart may even be evoked by brief episodes of ischemia and reperfusion in other organs. The present study investigates a possible role for NFkappaB and inducible nitric oxide synthase (iNOS) in adaption to ischemia by remote, delayed protection. METHODS: Mice (wild-types, or with targeted deletions of the NFkappaB p105 or the iNOS gene) were subjected to cycles of occlusion and reperfusion of both hind limbs, and 24 h later their hearts were isolated and Langendorff-perfused with induced global ischemia and reperfusion. Infarct size was measured. Skeletal muscles from ischemized limbs as well as hearts were also collected for polymerase chain reaction (PCR) and electromobility shift assay (EMSA). RESULTS: Hind limb preconditioning protected left ventricular function and reduced infarct size during reperfusion in wild-type mice. Nuclear translocation of NFkappaB was detected in both heart and preconditioned skeletal muscle 1-2 h after the preconditioning episodes (EMSA); while cardiac mRNA for iNOS gradually increased in a 24-h time course after hind limb preconditioning (real-time PCR). When hind limbs of mice with targeted deletions for the p105 subunit of NFkappaB or the iNOS gene were preconditioned, no beneficial effect was observed in the heart. CONCLUSIONS: Delayed cardioprotection induced by hind limb preconditioning involves signaling through NFkappaB and iNOS.

Does enteral contrast increase the accuracy of appendicitis diagnosis?

BACKGROUND: Several approaches traditionally have helped opacify the bowel when computed tomography (CT) is used to diagnose appendicitis. With the development of multidetector row CT (MDCT), the need for enteral contrast agents is less obvious. Purpose The objective of this study was to evaluate retrospectively the accuracy of MDCT demonstration of appendicitis using enteral contrast agents. METHODS: We reviewed radiologic reports of all 246 adult patients with suspected appendicitis who underwent 16-slice MDCT during 2005-2006 at our department. The use of enteral contrast agents and the route of administration were documented by one investigator. A radiologist evaluated whether the responses in the reports were consistent with diagnosis of appendicitis. The accuracy of the radiologic reports was assessed using the results of surgery, histopathology and 3 to 21 months of follow-up. RESULTS: Of patients studied, 14.6% received no enteral contrast agent, 8.5% received both oral contrast and rectal contrast (enema), 46.7% received oral contrast and 30.1% received rectal contrast enemas. The accuracies for the CT diagnosis of appendicitis with different combinations of agents ranged from 95% to 100%, with no significant difference among groups. CONCLUSION: Our study shows that the accuracy for diagnosis of appendicitis by abdominal 16-slice MDCT is high regardless of enteral contrast use. Therefore, further use of enteral contrast agents for CT diagnosis of appendicitis in adults cannot be recommended.

Hemodynamics of the normal aorta compared to fusiform and saccular abdominal aortic aneurysms with emphasis on a potential thrombus formation mechanism.

Abdominal Aortic Aneurysms (AAAs), i.e., focal enlargements of the aorta in the abdomen are frequently observed in the elderly population and their rupture is highly mortal. An intra-luminal thrombus is found in nearly all aneurysms of clinically relevant size and multiply affects the underlying wall. However, from a biomechanical perspective thrombus development and its relation to aneurysm rupture is still not clearly understood. In order to explore the impact of blood flow on thrombus development, normal aortas (n = 4), fusiform AAAs (n = 3), and saccular AAAs (n = 2) were compared on the basis of unsteady Computational Fluid Dynamics simulations. To this end patient-specific luminal geometries were segmented from Computerized Tomography Angiography data and five full heart cycles using physiologically realistic boundary conditions were analyzed. Simulations were carried out with computational grids of about half a million finite volume elements and the Carreau-Yasuda model captured the non-Newtonian behavior of blood. In contrast to the normal aorta the flow in aneurysm was highly disturbed and, particularly right after the neck, flow separation involving regions of high streaming velocities and high shear stresses were observed. Naturally, at the expanded sites of the aneurysm average flow velocity and wall shear stress were much lower compared to normal aortas. These findings suggest platelets activation right after the neck, i.e., within zones of pronounced recirculation, and platelet adhesion, i.e., thrombus formation, downstream. This mechanism is supported by recirculation zones promoting the advection of activated platelets to the wall.

Cardioprotection mediated by rosiglitazone, a peroxisome proliferator-activated receptor gamma ligand, in relation to nitric oxide.

UNLABELLED: Activation of peroxisome proliferator-activated receptor (PPAR) gamma protects from myocardial ischemia/reperfusion injury. The aim of the study was to investigate whether the cardioprotective effect of PPARgamma is related to nitric oxide (NO). METHODS: Wild type (WT) and endothelial NO synthase (eNOS) knockout (KO) mice received 3 mg/kg of the PPARgamma agonist rosiglitazone or vehicle (n = 6-9 in each group) i. p. 45 min before anesthesia. The hearts were isolated, perfused in a Langendorff mode and subjected to global ischemia and 30 min reperfusion. The hearts of another two groups of WT mice received the NOS inhibitor L-NNA (100 micromol/l) or vehicle in addition to pre-treatment with vehicle or rosiglitazone. RESULTS: In the WT heart, rosiglitazone increased the recovery of left ventricular function and coronary flow following ischemia in comparison with the vehicle group.L-NNA did not affect recovery per se but significantly blunted the improvement in the recovery of left ventricular function induced by rosiglitazone. In the KO group rosiglitazone suppressed the recovery of myocardial function following ischemia. Expression of eNOS was not affected, but phosphorylated eNOS was significantly increased by rosiglitazone in the WT hearts (P < 0.05). CONCLUSION: These results suggest that the cardioprotective effect of the PPARgamma agonist rosiglitazone is mediated via NO by phosphorylation of eNOS.

Lazaroid U-83836E improves tolerance to hemorrhagic shock and limb ischemia and reperfusion in rats and increases cardiac heat shock protein 72.

OBJECTIVES: Aminosteroids of the lazaroid type protect organs from ischemia-reperfusion damage. The authors hypothesized that lazaroid U-83836E may be beneficial in a shock model with hemorrhage combined with limb ischemia. Furthermore, the authors hypothesized that lazaroids induce expression of heat shock proteins (HSPs) of the 72-kDa family. METHODS: Rats were divided into two groups (lazaroid and control groups, n = 8 each) and pretreated with the lazaroid U-83836E (5 mg/kg) or with vehicle intraperitoneally at 12 and 24 hours before experiments. At the time of the experiment, rats were anesthetized, and the femoral artery of each rat was cannulated. After 20 minutes of stabilization, blood was shed from each rat to bring its mean arterial pressure to 24-28 mmHg for 2 hours. Bilateral tourniquets were tightened proximally on the rat thighs during those 2 hours and then released. Shed blood plus equal amounts of Ringer acetate then were infused to restore normal blood pressure, followed by a continuous infusion of Ringer acetate, the rate of which was regulated to maintain blood pressure, until 30 minutes after start of resuscitation. Fluid resuscitation was stopped, and rats were observed for another 3.5 hours. At the end of the observation period, the rats' hearts were collected for immunoblot analysis of HSP72. Additional hearts were collected from similarly pretreated rats not undergoing the episode of hemorrhagic shock and fluid resuscitation. RESULTS: Pretreatment with U-83836E improved mean arterial blood pressure after hemorrhagic shock and fluid resuscitation (p = 0.02), combined with improvements in acid-base balance (improved base excess and standard bicarbonate; p = 0.02 and p = 0.01, respectively). Western blot of cardiac protein extracts demonstrated that lazaroid pretreatment increased expression of HSP72. CONCLUSIONS: Pretreatment with the lazaroid U-83836E improved outcome markers in this hemorrhagic shock model. The observed protection may be caused by increased expression of HSP72.

Role of tumor necrosis factor alpha and its receptor I in preconditioning by hyperoxia.

Hyperoxic pretreatment (>95% O(2)) can evoke myocardial adaptation to ischemia, a method which is potentially clinically usable. We wanted to investigate the role of tumor necrosis factor alpha (TNFalpha) and its p55 receptor (receptor I) in signaling of hyperoxic adaptation to ischemia. Mice deficient for TNFalpha (TNFalpha -/-) or the TNF receptor I (TNFRI -/-) gene and their wild types were subjected to 60 minutes of hyperoxia or sham treatment. Their lungs were then collected for immunoblotting, their hearts isolated and subjected to global ischemia and reperfusion in a Langendorff system, and aortic rings mounted in organ baths for reactivity studies. Hyperoxia increased expression of TNFalpha and TNFalpha converting enzyme in pulmonary proteins from wild type mice, in which hyperoxia increased myocardial tolerance to ischemia. Post-ischemic heart function was improved and infarct size reduced in wild type mice, but not in TNFalpha -/- or TNFRI -/-. The contractile response to TNFalpha on aortic rings was attenuated by hyperoxic pretreatment and by TNFRI -/-. Thus we conclude that TNFalpha, acting through TNFRI, appears important for the protective effects of hyperoxia.