Silent T2* cerebral microbleeds: A potential new imaging clue in infective endocarditis

MRI of unruptured infectious intracranial aneurysms in infective endocarditis. A case-control study

PURPOSE

To evaluate the usefulness of T2* and FLAIR sequences in the detection of unruptured infectious intracranial aneurysms (UIIAs) in infective endocarditis (IE) including the relationships between the lesion patterns within subarachnoid spaces and the presence of UIIA.

METHODS

Retrospective review of 15 consecutive patients with definite IE undergoing MR imaging (FLAIR, T2*, DWI, CE-MRA, 3D-T1, CE-3DT1 sequences), in whom DSA detected infectious intracranial aneurysms (IIA). Aneurysmal features (diameter, location, morphology on DSA) and signal patterns onT2*, FLAIR and conventional MR sequences at the site of the UIIA, follow-up MRI and IE background, were analyzed. A control-group of 15 IE-patients without IIA at DSA served for comparison.

RESULTS

Among 17 UIIAs studied, T2* sequence displayed a susceptibility vessel sign in 15/17 (88.2%), both distal and proximal, which matched with the IIA visualized on DSA. Three patterns of hyposignal areas were identified: (a) signet-ring or target-sign appearance (n = 7), (b) homogeneous, round-, oval- or pear-shaped area (n = 4), and (c) heterogeneous area (n = 4). A FLAIR hyperintensity of the lumen and of the adjacent cortex was present in 6 (35.3%) and 9 (53%) UIIAs, respectively. On T1 (12 UIIAs) a rounded hyposignal (n = 2), within the UIIA lumen matched with the FLAIR hypersignal. Using both T2* and FLAIR had an incremental value with 100% sensitivity and specificity.

CONCLUSION

The susceptibility vessel sign is an MR imaging pattern frequently observed at the site of UIIAs in IE-patients. Both T2* and FLAIR may have the potential to depict UIIAs, regardless of their location and shape.

Delayed Tentorial Subdural Hematoma Caused by Traumatic Posterior Cerebral Artery Aneurysm: A Case Report and Literature Review

BACKGROUND Subdural hematoma (SDH) caused by traumatic intracranial aneurysm (TICA) is rare. TICAs are known to rupture easily, resulting in a high morbidity and mortality rate. Therefore, accurate diagnosis and treatment are crucial for preserving life. We describe a case of delayed SDH in the setting of posterior cerebral artery (PCA) aneurysm. CASE REPORT A 42-year-old man presented with sustained head injury from a traffic accident, and was being followed-up conservatively for traumatic SDH and subarachnoid hemorrhage. Three weeks after the head trauma, the patient developed a sudden deterioration of mental status and disorientation. Computed tomography revealed de novo SDH at the cerebellar tentorium. Computed tomography angiography and magnetic resonance imaging demonstrated TICA in the PCA. The patient was diagnosed with SDH due to a ruptured PCA aneurysm at the quadrigeminal segment. To avoid SDH growth due to re-rupture of the aneurysm, parent artery occlusion was subsequently performed with no complications. The patient was discharged home 2 months after endovascular treatment, with moderate disability. Follow-up angiography 2 years after the operation showed no recanalization, and the patient had returned to work. CONCLUSIONS TICA in the PCA can cause tentorial SDH with or without the presence of subarachnoid hemorrhage. Routine cerebrovascular assessment is crucial for head trauma with hematoma adjacent to the cerebellar tentorium. Parent artery occlusion via an endovascular procedure is an alternative treatment for TICA in the PCA that is less invasive than other approaches.

MRI versus CT in the detection of brain lesions in patients with infective endocarditis before or after cardiac surgery

Purpose

Imaging of brain involvement in infective endocarditis can drive the clinical management of this serious condition. MRI is very sensitive, but CT is more readily available. In this retrospective study, we compared the detection rates of CT and MRI.

Methods

After Ethics Committee approval, we retrospectively reviewed a series of 20 patients (13 males, median age 64 years) who underwent both CT and MRI either before or after cardiac surgery for definite infective endocarditis. Plain CT and MRI were evaluated for acute ischemic lesions, both punctuate and large, intraparenchymal hemorrhages, cerebral microbleeds, subarachnoid hemorrhages, abscesses, microabscesses, and meningitis. Qualitative assessment and McNemar test were performed. The value of contrast-enhanced scans (MRI, n = 14; CT, n = 9) and cognitive status were also assessed.

Results

A total of 166 lesions were identified on either technique: 137 (83%) on MRI only, 4 (2%) on CT only, and 25 (15%) on both techniques (p < 0.001). For these last 25 lesions, concordance on lesion type was only 16/25 (64%). MRI detected more microbleeds and ischemic lesions, while the 4 CT-only findings were false positives. Contrast-enhanced scans identified 68 enhancing lesions, mainly abscesses and microabscesses, and allowed a better characterization for 61/117 lesions (52%) with MRI, and for 11/81 (14%) with CT. Follow-up identified mild cognitive impairment in 6/13 and dementia in 3/13 patients.

Conclusion

While CT rapidly excludes large hemorrhages in patients with infective endocarditis, MRI accurately distinguishes the whole spectrum of brain lesions, including small ischemic lesions, microbleeds, and microabscesses.

Is brain angio-MRI useful in infective endocarditis management?

In infective endocarditis (IE), brain magnetic resonance imaging (MRI) is helpful to diagnose clinically silent neurological events. We assessed the usefulness of systematic early brain MRI in IE diagnosis and medico-surgical management. Over a period of 1 year, all patients admitted in one of the three hospitals participating in and fulfilling the Duke criteria for definite or possible IE underwent cerebral MRI within 7 days of IE suspicion. Eight panels of experts analyzed the records a posteriori. For each case, one record with and one record without the MRI results were randomly assigned to two panels, which determined the theoretical diagnosis and treatment. Paired comparisons were performed using a symmetry test. Thirty-seven brain MRIs were performed within a median of 5 days after inclusion. MRI was pathological in 26 patients (70 %), showing 62 % microischemia and 58 % microbleeds. The expert advice did not differ significantly between the two evaluations (with or without the MRI results). The therapeutic strategies determined diverged in five cases (13.5 %). Diagnosis differed in two cases (5.4 %), with an upgrading of diagnosis from possible to definite IE using MRI results. Early brain MRI did not significantly affect the IE diagnosis and medico-surgical treatment plan. These results suggest that systematic use of early brain MRI is irrelevant in IE. Further studies are necessary to define whether MRI is mandatory in IE management within a multidisciplinary approach, with particular attention paid to better timing and the subset of patients in whom this imaging examination could be beneficial.

Cerebral imaging in infectious endocarditis: A clinical study

BACKGROUND

Because neurological failure is the most frequent extra-cardiac complication in Infectious Endocarditis (IE), a brain computerised tomography (CT) scan is usually performed. The benefits of magnetic resonance imaging (MRI) have not been clearly established. This study aims to clarify the prevalence and type of cerebral lesions in IE detected using MRI and to compare them with those detected using CT scans.

METHODS

In the Grenoble University Hospital, patients diagnosed with definite or possible endocarditis according to Duke's criteria were screened from 2010-2012. Brain CT and MRI were performed as soon as possible after diagnosis.

RESULTS

Of the 62 patients with IE who underwent at least one cerebral imaging within 3 weeks of diagnosis, Streptococcus (29) and Staphylococcus (14) were the main micro-organisms present. Twenty-eight (45%) patients underwent cardiac surgery. Eight (13%) died before discharge. Twenty (32%) had neurological symptoms. A brain CT-scan was performed on 53 (85%) patients and a MRI was performed on 43 (69%) patients. CT was pathological in 26 (49%) patients, whereas 32 (74%) MRI demonstrated abnormalities. The MRI lesions were classified as follows: ischaemia (48%), microbleeds (34%), haemorrhages (16%), abscesses (9%) and microbial aneurysms (4%). Of the 37 patients who underwent both MRI and CT examinations, ischaemia (48% vs 35%) and microbleeds (34%) demonstrated the difference between the two imaging methods.

CONCLUSION

Through the early diagnosis of cerebral damage, even in asymptomatic cases, MRI may have a role in the IE management, influence any surgical decision and assist in prognosis assessment.

Neurologic complications in infective endocarditis: identification, management, and impact on cardiac surgery

Neurologic complications of infective endocarditis (IE) are common and frequently life threatening. Neurologic events are not always obvious. The prediction and management of neurologic complications of IE are not easily approached algorithmically, and the impact they have on timing and ability to surgically repair or replace the affected valve often requires a painstaking evaluation and joint effort across multiple medical disciplines in order to achieve the best possible outcome. Although specific recommendations are always tailored to the individual patient, there are some guiding principles that can be used to help direct the decision-making process. Herein, we review the pathophysiology, epidemiology, manifestations, and diagnosis of neurological complications of IE and further consider the impact they have on clinical decision making.

Usefulness of anticoagulant therapy in the prevention of embolic complications in patients with acute infective endocarditis

Background. The use of anticoagulant therapy (ACT) in patients with acute infective endocarditis (IE) remains a controversial issue. Our study attempts to estimate the impact of ACT on the occurrence of embolic complications and the usefulness of ACT in the prevention of embolism in IE patients. Methods. The present authors analyzed 150 patients with left-sided IE. Embolisms including cerebrovascular events (CVE) and the use of ACT were checked at the time of admission and during hospitalization. Results. 57 patients (38.0%) experienced an embolic event. There was no significant difference in the incidence of CVE and in-hospital mortality between patients with and without warfarin use at admission, although warfarin-naïve patients were significantly more likely to have large (>1 cm) and mobile vegetation. In addition, there was no significant difference in the incidence of postadmission embolism and in-hospital death between patients with and without in-hospital ACT. On multivariate logistic regression analysis, ACT at admission was not significantly associated with a lower risk of embolism in patients with IE. Conclusions. The role of ACT in the prevention of embolism was limited in IE patients undergoing antibiotic therapy, although it seems to reduce the embolic potential of septic vegetation before treatment.

Brain MRI findings in neurologically asymptomatic patients with infective endocarditis

BACKGROUND AND PURPOSE

Neurologic complications in infective endocarditis are frequent and affect patient prognosis negatively. Additionally, detection of asymptomatic lesions by MR imaging could help early management of this condition. The objective of our study was to describe MR imaging characteristics of cerebral lesions in a neurologically asymptomatic population with infective endocarditis.

MATERIALS AND METHODS

One hundred nine patients at the acute phase of a definite or possible infective endocarditis according to the Duke modified criteria and without neurologic manifestations according to the NIHSS were prospectively included. Each patient underwent cerebral MR imaging and MRA within 7 days of admission.

RESULTS

MR imaging showed abnormalities in 78 patients (71.5%). Acute ischemic lesions (40 patients, 37%) and cerebral microbleeds (62 patients, 57%) were the most frequent lesions. Eight patients had an acute SAH, 3 patients had brain microabscesses, 3 had a small cortical hemorrhage, and 3 had a mycotic aneurysm. Acute ischemic lesions mostly appeared as multiple small infarcts disseminated in watershed territories (25/40, 62.5%) and as lesions of different ages (21/40, 52.5%). Cerebral microbleeds were preferentially distributed in cortical areas (362/539 cerebral microbleeds, 67%). No significant correlation was found among lesions, in particular between acute ischemia and cerebral microbleeds.

CONCLUSIONS

Occult cerebral lesions, in particular cerebral microbleeds and acute ischemic lesions, are frequent in infective endocarditis. The MR imaging pattern of acute small infarcts of different ages predominating in watershed territories and cortical cerebral microbleeds may represent a surrogate imaging marker of infective endocarditis.

Thrombolysis for stroke caused by infective endocarditis: an illustrative case and review of the literature

Infective endocarditis represents a classical contra-indication to thrombolysis for acute ischemic stroke due to a potential increased risk of intracranial hemorrhage. However, some case reports have suggested safety and potential efficacy of intravenous or intra-arterial thrombolysis in stroke related to infective endocarditis. We present a case of ischemic stroke related to infective endocarditis who was treated with intravenous tissue plasminogen activator within the first 3 h of symptoms onset and subsequently developed symptomatic multifocal intracerebral hemorrhages, and summarize currently available data on this issue.

Cerebral microbleeds predict impending intracranial hemorrhage in infective endocarditis

BACKGROUND

Cerebral microbleeds (CMBs) detected by T2*-weighted MRI are a potential indicator of hypertension, microvascular disease and hemorrhagic stroke. An association between infective endocarditis (IE) and CMBs has been reported recently, but the clinical significance remains unclear. We hypothesized that CMBs in patients with IE are associated with vascular vulnerabilities such as mycotic aneurysm or pyogenic vasculitis.

METHODS

We retrospectively reviewed 26 consecutive patients with definite IE who underwent T2*-weighted MRI and were admitted to 2 medical centers in Osaka, Japan, between January 2006 and June 2010. We examined the incidence of symptomatic intracranial hemorrhage (ICH) occurring after initial MRI examination and investigated the association between ICH, CMBs and other clinical characteristics.

RESULTS

CMBs were identified in 14 patients (54%), and 72% of CMBs were found in the lobar region. Symptomatic ICH was observed in 8 patients (31%) during the 3-month follow-up period after initial MRI examination. In multiple logistic regression analyses, the presence of preceding ICH [odds ratio (OR) 40.0, 95% confidence interval (CI) 2.5-2,870] and the presence of CMBs (OR 34.0, 95% CI 1.3-17,300) were independent predictors of the development of ICH. Using cutoff values for CMBs of ≥2 and ≥3, the adjusted ORs for ICH increased (OR 42.1, 95% CI 1.9-24,300, and OR 70.1, 95% CI 2.5-105,000, respectively).

CONCLUSIONS

In addition to prior ICH, the presence of CMBs was a strong predictor of impending ICH in patients with IE. CMBs might represent vascular vulnerability related to IE.

The importance of preoperative magnetic resonance imaging in valve surgery for active infective endocarditis

PURPOSE

Valve surgery for active infective endocarditis (IE) can cause fatal brain hemorrhage. Our current study aimed to evaluate the incidence of septic cerebral lesions in active IE patients by performing preoperative magnetic resonance imaging (MRI) including T(2)*- weighted sequences and magnetic resonance angiography (MRA) before urgent valve surgery, and to investigate whether such preoperative evaluation affects postoperative outcomes.

METHODS

Eighteen patients were referred to our department for native valve IE during 2006-2010. Urgent surgery was indicated in cases of hemodynamic failure resulting from valve destruction, refractory sepsis, and mobile vegetations measuring >10 mm. For these patients, we performed preoperative MRI and MRA.

RESULTS

Males comprised 67% of the subjects, with average age 53 ± 15 years. No clinical evidence of acute stroke was noted. Of the 18 patients, urgent surgery was indicated in 15; of these, 10 (67%) showed a brain lesion related to IE: 6 patients had acute or subacute brain infarctions, 2 patients had brain infarction with brain abscess, and 2 patients had hemorrhagic brain infarction and so did not undergo urgent surgery. Thus, 13 patients underwent urgent valve surgery. Among the 5 patients who did not undergo urgent surgery, 4 patients later underwent valve surgery for healed IE. No hospital deaths or neurological complications occurred.

CONCLUSION

MRI of patients with active IE revealed a high incidence of cerebral lesions caused by IE. The use of MRI to detect septic embolism and intracerebral hemorrhage may provide important information for better surgical outcomes.

Significance of the T2*-weighted gradient echo brain imaging in patients with infective endocarditis

BACKGROUND

Although aneurysm formation accompanying parenchymal hemorrhage is one of devastating complications in the central nerves system (CNS), imaging studies of the brain are not routinely warranted in patients with infective endocarditis (IE). To assess the clinical importance for detecting silent lesions in the central nervous system, we investigated hypointense signal spots detected on the brain T2*-weighted MR imaging in patients with IE.

METHODS AND RESULTS

Eleven patients with IE were retrospectively reviewed. Seven patients (63.6%) showed hypointense signal spots on T2*-weighted MR images. The number of hypointense signal spots increased within only a few weeks in five patients.

CONCLUSION

The brain T2*-weighted MR imaging in patients with IE may have a potential role to detect CNS lesions with clinical significance of potentially high risk of intracranial hemorrhage. T2*-weighted hypointense signal spots may be specific to brain involvement, and be quite useful in monitoring CNS lesions associated with IE, even if they are asymptomatic.

Multimodal MRI for ischemic stroke: from acute therapy to preventive strategies

Background and Purpose

Conventional therapies for ischemic stroke include thrombolytic therapy, prevention of inappropriate coagulation and thrombosis, and surgery to repair vascular abnormalities. Over 10 years have passed since the US Food and Drug Administration approved intravenous tissue plasminogen activator for use in acute stroke patients, but most major clinical trials have failed during the last 2 decades, including large clinical trials for secondary prevention and neuroprotection. These results suggest the presence of heterogeneity among stroke patients. Neuroimaging techniques now allow changes to be observed in patients from the acute to the recovery phase. The role of MRI in stroke evaluation and treatment is discussed herein.

Main Contents

Three MRI strategies are discussed with relevant examples. First, the following MRI strategies for acute ischemic stroke are presented: diffusion-perfusion mismatch, deoxygenation (oxygen extraction and cerebral metabolic rate of oxygen), and blood-brain barrier permeability derangement in selected patients for recanalization therapy. Second, multimodal MRI for identifying stroke mechanisms and the specific causes of stroke (i.e., patent foramen ovale, infective endocarditis, and nonbacterial thrombotic endocarditis) are presented, followed by MRI strategies for prevention of recurrent stroke: plaque images and flow dynamics for carotid intervention.

Expectations

The studies reviewed herein suggest that using MRI to improve the understanding of individual pathophysiologies will further promote the development of rational stroke therapies tailored to the specifics of each case.

Brain magnetic resonance findings in infective endocarditis with neurological complications

PURPOSE

Diagnosing infective endocarditis and its complications can be difficult because of the nonspecific symptoms. We reviewed findings of intracranial abnormalities on magnetic resonance imaging (MRI) in 14 patients with neurological complications and herein discuss the overall intracranial MRI findings.

MATERIALS AND METHODS

We retrospectively reviewed patients with infective endocarditis from August 2004 to August 2006. Brain MRI, the causative bacteria, and abnormal neurological symptoms were reviewed for 14 patients with neurological complications.

RESULTS

Of the 14 patients, 13 showed intracranial abnormalities on MRI. Embolization was seen in 10 patients, hemorrhage in 3, abscess formation in 3, and encephalitis in 2. Hyperintense lesions with a central hypointense area on T2-weighted and/or T2*-weighted imaging (Bull's-eye-like lesion) were seen in four patients. A combination of these intracranial abnormalities was observed in 6 patients.

CONCLUSION

The MRI findings associated with infective endocarditis are wide-ranging: embolization, hemorrhage, meningitis, cerebritis, abscess, the bull's-eye-like lesion. Clinicians should consider the possibility of infective endocarditis in patients with unknown fever and neurological abnormality. Brain MRI should be promptly performed for those patients, and T2*-weighted imaging is recommended for an early diagnosis of infective endocarditis.

Susceptibility weighted imaging: a new tool in magnetic resonance imaging of stroke

Susceptibility weighted imaging (SWI) is a magnetic resonance (MR) technique that is exquisitely sensitive to paramagnetic substances, such as deoxygenated blood, blood products, iron, and calcium. This sequence allows detection of haemorrhage as early as 6h and can reliably detect acute intracerebral parenchymal, as well as subarachnoid haemorrhage. It detects early haemorrhagic transformation within an infarct and provides insight into the cerebral haemodynamics following stroke. It helps in the diagnosis of cerebral venous thrombosis. It also has applications in the work-up of stroke patients. The sequence helps in detecting microbleeds in various conditions, such as vasculitis, cerebral autosomal dominant arteriopathy, subacute infarcts and leucoencephalopathy (CADASIL), amyloid angiopathy, and Binswanger's disease. The sequence also aids in the diagnosis of vascular malformations and perinatal cerebrovascular injuries. This review briefly illustrates the utility of this MR technique in various aspects of stroke diagnosis and management.