Edema progression in proximity to traumatic microbleeds: evolution of cytotoxic and vasogenic edema on serial MRI

Introduction

Although cerebral edema is common following traumatic brain injury (TBI), its formation and progression are poorly understood. This is especially true for the mild TBI population, who rarely undergo magnetic resonance imaging (MRI) studies, which can pick up subtle structural details not visualized on computed tomography, in the first few days after injury. This study aimed to visually classify and quantitatively measure edema progression in relation to traumatic microbleeds (TMBs) in a cohort of primarily mild TBI patients up to 30 days after injury. Researchers hypothesized that hypointense lesions on Apparent Diffusion Coefficient (ADC) detected acutely after injury would evolve into hyperintense Fluid Attenuated Inversion Recover (FLAIR) lesions.

Methods

This study analyzed the progression of cerebral edema after acute injury using multimodal MRI to classify TMBs as potential edema-related biomarkers. ADC and FLAIR MRI were utilized for edema classification at three different timepoints: ≤48 hours, ~1 week, and 30 days after injury. Hypointense lesions on ADC (ADC+) suggested the presence of cytotoxic edema while hyperintense lesions on FLAIR (FLAIR+) suggested vasogenic edema. Signal intensity Ratio (SIR) calculations were made using ADC and FLAIR to quantitatively confirm edema progression.

Results

Our results indicated the presence of ADC+ lesions ≤48 hours and ~1 week were associated with FLAIR+ lesions at ~1 week and 30 days, respectively, suggesting some progression of cytotoxic edema to vasogenic edema over time. Ten out of 15 FLAIR+ lesions at 30 days (67%) were ADC+ ≤48 hours. However, ADC+ lesions ≤48 hours were not associated with FLAIR+ lesions at 30 days; 10 out of 25 (40%) ADC+ lesions ≤48 hours were FLAIR+ at 30 days, which could indicate that some lesions resolved or were not visualized due to associated atrophy or tissue necrosis. Quantitative analysis confirmed the visual progression of some TMB lesions from ADC+ to FLAIR+. FLAIR SIRs at ~1 week were significantly higher when lesions were ADC+ ≤48 hours (1.22 [1.08-1.32] vs 1.03 [0.97-1.11], p=0.002).

Conclusion

Awareness of how cerebral edema can evolve in proximity to TMBs acutely after injury may facilitate identification and monitoring of patients with traumatic cerebrovascular injury and assist in development of novel therapeutic strategies.

Traumatic microbleeds suggest vascular injury and predict disability in traumatic brain injury

Traumatic microbleeds are small foci of hypointensity seen on T2*-weighted MRI in patients following head trauma that have previously been considered a marker of axonal injury. The linear appearance and location of some traumatic microbleeds suggests a vascular origin. The aims of this study were to: (i) identify and characterize traumatic microbleeds in patients with acute traumatic brain injury; (ii) determine whether appearance of traumatic microbleeds predict clinical outcome; and (iii) describe the pathology underlying traumatic microbleeds in an index patient. Patients presenting to the emergency department following acute head trauma who received a head CT were enrolled within 48 h of injury and received a research MRI. Disability was defined using Glasgow Outcome Scale-Extended ≤6 at follow-up. All magnetic resonance images were interpreted prospectively and were used for subsequent analysis of traumatic microbleeds. Lesions on T2* MRI were stratified based on 'linear' streak-like or 'punctate' petechial-appearing traumatic microbleeds. The brain of an enrolled subject imaged acutely was procured following death for evaluation of traumatic microbleeds using MRI targeted pathology methods. Of the 439 patients enrolled over 78 months, 31% (134/439) had evidence of punctate and/or linear traumatic microbleeds on MRI. Severity of injury, mechanism of injury, and CT findings were associated with traumatic microbleeds on MRI. The presence of traumatic microbleeds was an independent predictor of disability (P < 0.05; odds ratio = 2.5). No differences were found between patients with punctate versus linear appearing microbleeds. Post-mortem imaging and histology revealed traumatic microbleed co-localization with iron-laden macrophages, predominately seen in perivascular space. Evidence of axonal injury was not observed in co-localized histopathological sections. Traumatic microbleeds were prevalent in the population studied and predictive of worse outcome. The source of traumatic microbleed signal on MRI appeared to be iron-laden macrophages in the perivascular space tracking a network of injured vessels. While axonal injury in association with traumatic microbleeds cannot be excluded, recognizing traumatic microbleeds as a form of traumatic vascular injury may aid in identifying patients who could benefit from new therapies targeting the injured vasculature and secondary injury to parenchyma.

Nonhomogeneous Gadolinium Retention in the Cerebral Cortex after Intravenous Administration of Gadolinium-based Contrast Agent in Rats and Humans

Background Gadolinium retention after repeated gadolinium-based contrast agent (GBCA) exposure has been reported in subcortical gray matter. However, gadolinium retention in the cerebral cortex has not been systematically investigated. Purpose To determine whether and where gadolinium is retained in rat and human cerebral cortex. Materials and Methods The cerebral cortex in Sprague-Dawley rats treated with gadopentetate dimeglumine (three doses over 4 weeks; cumulative gadolinium dose, 7.2 mmol per kilogram of body weight; n = 6) or saline (n = 6) was examined with antemortem MRI. Two human donors with repeated GBCA exposure (three and 15 doses; 1 and 5 months after exposure), including gadopentetate dimeglumine, and two GBCA-naive donors were also evaluated. Elemental brain maps (gadolinium, phosphorus, zinc, copper, iron) for rat and human brains were constructed by using laser ablation inductively coupled plasma mass spectrometry. Results Gadopentetate dimeglumine-treated rats showed region-, subregion-, and layer-specific gadolinium retention in the neocortex (anterior cingulate cortex: mean gadolinium concentration, 0.28 µg ∙ g^-1 ± 0.04 [standard error of the mean]) that was comparable (P > .05) to retention in the allocortex (mean gadolinium concentration, 0.33 µg ∙ g^-1 ± 0.04 in piriform cortex, 0.24 µg ∙ g^-1 ± 0.04 in dentate gyrus, 0.17 µg ∙ g^-1 ± 0.04 in hippocampus) and subcortical structures (0.47 µg ∙ g^-1 ± 0.10 in facial nucleus, 0.39 µg ∙ g^-1 ± 0.10 in choroid plexus, 0.29 µg ∙ g^-1 ± 0.05 in caudate-putamen, 0.26 µg ∙ g^-1 ± 0.05 in reticular nucleus of the thalamus, 0.24 µg ∙ g^-1 ± 0.04 in vestibular nucleus) and significantly greater than that in the cerebellum (0.17 µg ∙ g^-1 ± 0.03, P = .01) and white matter tracts (anterior commissure: 0.05 µg ∙ g^-1 ± 0.01, P = .002; corpus callosum: 0.05 µg ∙ g^-1 ± 0.02, P = .001; cranial nerve: 0.02 µg ∙ g^-1 ± 0.01, P = .004). Retained gadolinium colocalized with parenchymal iron. T1-weighted MRI signal intensification was not observed. Gadolinium retention was detected in the cerebral cortex, pia mater, and pia-ensheathed leptomeningeal vessels in two GBCA-exposed human brains but not in two GBCA-naive human brains. Conclusion Repeated gadopentetate dimeglumine exposure is associated with gadolinium retention in specific regions, subregions, and layers of cerebral cortex that are critical for higher cognition, affect, and behavior regulation, sensorimotor coordination, and executive function. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Kanal in this issue.

Cost-effectiveness analysis of inhaled zanamivir in the treatment of influenza A and B in high-risk patients

OBJECTIVE

To evaluate the cost effectiveness of zanamivir 10 mg twice daily for 5 days in the treatment of influenza in high-risk patients.

DESIGN

Bootstrap cost-effectiveness analysis incorporating within-trial analysis of pooled patient-level cost and effect data.

SETTING

UK unit costs and utilities applied to high-risk patients drawn from 6 multinational clinical trials.

PATIENTS

A total of 154 zanamivir and 167 placebo high-risk patients were included in the analysis.

MAIN OUTCOME MEASURES

Cost per day of normal activities; cost per symptom-free day; cost per complication averted; cost per quality-adjusted life-year (QALY).

RESULTS

The mean benefit was estimated to be 2.5 days [95% confidence interval (CI): 0.68 to 4.27] of normal activities gained; 2.0 (95% CI: 0.56 to 3.51) symptom-free days; and a 9% reduction in complications (95% CI: 0 to 18%). Excluding the effect of rare hospitalisation costs, the cost (1999 values) of gaining a day of normal activities was 9.50 Pounds (95% CI: 5 Pounds to 39 Pounds); cost per symptom-free day was 11.56 Pounds (95% CI: 6 Pounds to 43 Pounds); cost per complication averted was 262 Pounds (95% CI: 90 Pounds to 1574 Pounds). Influenza was estimated to reduce utility by 0.883 per day, demonstrating the debilitating effect of the disease. Extrapolating a day of normal activities to a standard utility measure resulted in a cost per QALY of 3900 Pounds excluding inpatient costs (7490 Pounds including inpatient costs). Cost-effectiveness acceptability curves demonstrated 90% certainty that zanamivir would be cost effective at 8000 Pounds per QALY.

CONCLUSIONS

Significant health benefits can be obtained with zanamivir treatment in high-risk patients. The cost per QALY for zanamivir in these patients compares well with that of other commonly used pharmacological interventions.

Novel surveillance and cure of a donor-transmitted lymphoma in a renal allograft recipient

BACKGROUND

In this report we describe a malignant lymphoma of donor origin inadvertently transplanted into two renal allograft recipients, despite standard comprehensive donor screening. The successful clearance of the tumor from both patients and a novel method of surveillance are detailed.

METHODS

Initial management consisted of withdrawal of immunosuppression to promote rejection of the allograft and the transplanted tumor in both patients, followed by graft removal. Peripheral blood microchimerism was assessed in both recipients using nested polymerase chain reaction to detect the DYZ3 gene on the Y chromosome (donor male, recipients female).

RESULTS

Although microchimerism was detected on day 6 after transplantation and day 1 after explantation, repeat peripheral blood examination at 1, 3, and 6 months after explantation demonstrated no microchimerism. Both patients remain well at 12 months and have been relisted for transplantation.

CONCLUSION

Despite inadvertent transplantation of a previously undiagnosed malignancy of donor origin, the recipients' immune response was able to eliminate donor tumor cells after the withdrawal of immunosuppression. Repeated surveillance of peripheral blood from both recipients, using a novel application of the technique of nested polymerase chain reaction to amplify donor DNA, demonstrated no persistence of donor cells, supporting effective eradication of the donor malignancy.

Cost effectiveness of zanamivir for the treatment of influenza in a high risk population in Australia

OBJECTIVE

To use data from a clinical trial of zanamivir, a new antiviral drug, to estimate the costs and effectiveness of alternative treatment strategies for a high-risk population in Australia visiting a physician for treatment of influenza or influenza-like illness within 36 hours of symptom onset.

DESIGN AND SETTING

This was a modelling study using data from a randomised, double-blind, placebo-controlled trial with centres in Australia, New Zealand and South Africa. Cost data were taken from standard Australian sources.

METHODS

Efficacy data from the clinical trial were used to populate a computer model designed to estimate the costs and health outcomes associated with alternative treatments for influenza and influenza-like illness. Only patients who consulted the physician within 36 hours of symptom onset were included in this trial. Cost data were used to translate the clinical data into treatment cost estimates.

RESULTS

Treatment with zanamivir for this high risk population results in an incremental cost of $A14.20 per day of symptoms avoided in the base case. The cost per quality-adjusted life-year (QALY) gained is $A11,715. The results are sensitive to several parameter values, including the influenza-positive rate and the impact of zanamivir on days to alleviate symptoms and hospitalisation.

CONCLUSIONS

Influenza is costly for the high risk population who seek physician treatment. Treatment with zanamivir for this population is cost effective based on an $A78,000 per QALY benchmark. Zanamivir could be cost saving if it reduces the hospitalisation rate.

Impact of zanamivir treatment on productivity, health status and healthcare resource use in patients with influenza. Zanamivir Study Group

OBJECTIVE

This study examined the impact of zanamivir treatment on patient morbidity in patients with influenza.

DESIGN AND SETTING

This was a multicentre, randomised, double-blind, parallel-group study conducted in 14 countries in Europe and North America during the winter of 1995/1996.

PATIENTS AND PARTICIPANTS

The study included 722 individuals with virologically confirmed influenza.

INTERVENTIONS

Two different zanamivir treatment regimens [twice daily (bid) or 4 times daily (qid) for 5 days] were compared with placebo.

MAIN OUTCOME MEASURES AND RESULTS

Efficacy was measured using a number of patient-assessment questionnaires. Results showed that significantly fewer patients with influenza who were treated with zanamivir had additional contacts with healthcare professionals compared with those who received placebo (8 vs 14%; p < or = 0.049, bid and qid vs placebo). Individuals treated with zanamivir also spent fewer days absent from work (placebo: mean = 3.28 days; qid: mean = 2.52 days; p = 0.031) or college/school (placebo: mean = 2.90 days; bid: mean = 2.24 days; p = 0.032), and showed significant improvements in productivity compared with placebo. The health status questionnaire revealed significant improvements in patient well-being over the first 5 days of the study in those treated with zanamivir compared with those who received placebo.

CONCLUSIONS

Zanamivir treatment reduced absenteeism, improved patient productivity and well-being, and reduced the additional use of healthcare resources in patients with influenza.

Role of donor leukocyte chimerism in establishing the etiology of neutropenia after liver transplantation

BACKGROUND

The quantitation of donor leukocyte chimerism may aid in establishing the etiology of neutropenia after liver transplantation.

METHODS

The incidence and clinical and laboratory characteristics of severe neutropenia were studied in adults who have undergone liver transplantation at our institution over the last 4 years.

RESULTS

Severe neutropenia developed in 5 of 156 patients (3%). The clinical and pathological features were nonspecific. In two patients with a delayed diagnosis of graft-versus-host disease (GVHD), donor leukocytes comprised > or = 50% of the circulating peripheral blood mononuclear cells. In a third patient, an earlier diagnosis of GVHD was suspected on the basis of a donor leukocyte count of 3-10% in the peripheral blood. In contrast, donor leukocyte chimerism was < or = 0.01% in two patients with probable drug-induced neutropenia

CONCLUSIONS

The determination of donor leukocyte chimerism has an important role in the investigation of neutropenia after liver transplantation, allowing early diagnosis and treatment of GVHD.

A pharmacoeconomic model for the treatment of influenza

OBJECTIVE

The aim of this study was to develop a generic treatment algorithm for influenza and influenza-like illness (ILI) that could be used to estimate the costs and outcomes of current and new treatments for influenza in different countries for different patient subgroups.

METHODS

A series of possible treatment pathways was identified and the probabilities of different patient subgroups following each pathway were estimated by using the published literature. The health outcomes and health service use and unit costs for each pathway were estimated from trial data and standard data sources. An interactive computer model was created, the base-case input parameter values were assigned, and estimates of the current costs of influenza and ILI in different population subgroups estimated. Sensitivity analyses were performed by changing input parameter values.

RESULTS

The average healthcare cost of influenza and ILI per person in the US was $US72 for the general population and $US330 for a high risk population (1997 values). The average total cost per patient (healthcare cost plus productivity losses) was $US320 for the general population and $US546 for a high risk population. These costs are sensitive to changes in the proportion of patients visiting a physician and to the proportion of patients hospitalised with complications of the disease. Days to alleviate major symptoms and other health outcome measures are sensitive to the percentage of patients who receive antiviral therapy as well as to the efficacy of this therapy.

CONCLUSIONS

The costs and health outcomes of influenza and ILI depend on the extent to which patients visit a physician, the use of antiviral drugs, and the incidence of complications requiring hospital care. The computer model will allow decision-makers to assess the cost effectiveness and the potential budget impact of new antivirals for treating influenza.

The effect of venous drainage on glucose homeostasis after experimental pancreas transplantation

In this canine study, glucose homeostasis after clinical pancreas transplantation is complex, with the relative effect of systemic versus portal delivery of insulin remaining unresolved. Thirty-two pancreatectomized dogs received either systemic venous drainage (SVD) with bladder exocrine drainage (n = 16), or portal venous drainage (PVD) with gastric exocrine drainage (n = 16). Cyclosporine (CsA) based immunosuppression was commenced on day -7. The effect of immunosuppression was a significant increase in fasting blood glucose (FBGL) (P = 0.002), fasting insulin (P = 0.024), AUC for insulin (P = 0.009), and K values decreased (P = 0.009). FBGL and K values remained abnormal after transplantation with no significant difference seen between SVD and PVD. However, fasting insulin became significantly lower after PVD and AUC insulin fell in both groups. CsA levels fell in both groups after transplantation, mirroring the fall in AUC insulin, and implicating CsA as a major cause of peripheral resistance to insulin. In conclusion, PVD did not demonstrate a significant advantage over SVD in handling an intravenous glucose challenge. The need for pancreatectomy in large animals may make them an unsatisfactory experimental model to evaluate the glucoregulatory effects of pancreas allotransplantation.

Experimental hyperacute rejection in pancreas allotransplants

A model of sensitization by intraperitoneal lymph node inoculation was developed to test the hypothesis that hyperacute rejection (HAR) could occur in sensitized recipients of vascularized pancreas allografts. Ten pairs of outbred mongrel dogs that were lymphocytotoxic cross-match assay negative were inoculated with homogenized lymph nodes on either three or four occasions at fortnightly intervals before renal transplantation. A renal allograft from the same donor was used to test the HAR response and to further enhance sensitization by rejection of a vascularized organ. Pancreas transplants were performed 2 weeks later, with biopsies of the graft and blood samples taken at 0, 10, 20, and 30 min and then at 30-min intervals until the grafts were no longer viable. All renal and pancreas grafts were rejected in a classical hyperacute pattern. Within 4 min of revascularization of the pancreas, central lobular hemorrhage and vascular congestion appeared, followed by general edema. Histology demonstrated parallel changes of edema, vascular congestion, necrosis, hemorrhage, and leukocytic infiltrate, which all preceded graft infarction. A sharp decline in both arterial and venous white blood cell count and platelets occurred within 10 min of revascularization with initial sequestration and subsequent release of platelets from the graft (P=0.02). In summary, HAR of the allografted pancreas can be observed by the surgeon within minutes of revascularization, with predictable macroscopic and microscopic changes. This study supports the use of routine lymphocytotoxic cross-match tests for all recipients of pancreas transplants and implies that particular care is warranted in regraft pancreas allograft recipients.

Recovery of gastrointestinal function after renal transplantation in a patient with sclerosing peritonitis secondary to continuous ambulatory peritoneal dialysis

We describe the rapid and dramatic improvement in gastrointestinal function that occurred after successful renal transplantation in a women with severe sclerosing peritonitis secondary to continuous ambulatory peritoneal dialysis (CAPD). We postulate that the antiinflammatory effect of the immunosuppressive agents was the most important factor leading to the patient's recovery.