Diffusion-weighted MR imaging of pyogenic intraventricular empyema

Recurrent primary pyogenic ventriculitis in an adult woman: a case report

Background

Recurrent primary pyogenic ventriculitis has not been reported previously. We present a unique case of recurrent primary pyogenic ventriculitis in an adult. And we believe that our study makes a significant contribution to the literature.

Case presentation

An adult woman with uncontrolled diabetes experienced two episodes of pyogenic ventriculitis caused by Escherichia coli over 4 years. She had typical imaging features, and the source of infection was undetermined. After antibiotic treatment, she recovered fully.

Conclusions

Early recognition and therapy will improve patient prognosis.

MRI of Emergent Intracranial Infections and Their Complications

Acute intracranial infections of the central nervous system and skull base are uncommon but time sensitive diagnoses that may present to the emergency department. As symptoms are frequently nonspecific or lack typical features of an infectious process, a high index of suspicion is required to confidently make the diagnosis, and imaging may not only serve as the first clue to an intracranial infection, but is often necessary to completely characterize the disease process and exclude any confounding conditions. Although computed tomography is typically the initial imaging modality for many of these patients, magnetic resonance imaging offers greater sensitivity and specificity in diagnosing intracranial infections, characterizing the full extent of infection, and identifying potential complications. The aim of this article is to serve as a review of the typical and most important imaging manifestations of these infections that can be encountered in the emergent setting.

Brain Abscess Masquerading as Brain Infarction

Occasionally, acute ischemic stroke can be difficult to differentiate from acute intracranial infection. We describe a patient who presented with sudden onset of right hemiparesis and fever. Magnetic resonance imaging (MRI) was consistent with an acute stroke, showing multiple lesions with restricted diffusion in the left middle cerebral artery territory. These lesions were not enhancing and were not associated with vasogenic edema. A diagnosis of acute stroke was made based on the clinical and radiographic data. Follow-up MRI obtained eleven days later showed interval development of ring enhancement and vasogenic edema surrounding the previously noted core of restricted diffusion. Based on these findings, the diagnosis was revised to cerebral abscesses and the patient was treated successfully with antibiotics. In retrospect, the largest diffusion-weighted lesion on baseline MRI demonstrated two characteristics that were atypical for stroke: it had an ovoid shape and a subtle T2 hypointense core. This case demonstrates that acute clinical and radiographic presentation of cerebral abscess and ischemic stroke can be strikingly similar. Follow-up imaging can be instrumental in arriving at an accurate diagnosis.

Brain Imaging Findings and Neurologic Complications after Allogenic Hematopoietic Stem Cell Transplantation in Children

Hematopoietic stem cell transplantation (HSCT) is the only therapy for a subset of patients with malignant and nonmalignant diseases. Central nervous system (CNS) complications continue to be an important cause of morbidity and significantly contribute to mortality after HSCT. These complications include infections, cerebrovascular lesions, therapy-induced diseases, metabolic disturbances, and post-HSCT carcinogenesis. Following HSCT, three phases can be identified on the basis of the patient's immune status: the pre-engraftment period (<30 days after HSCT), the early postengraftment period (30-100 days after HSCT), and the late postengraftment period (>100 days after HSCT). There is a distinct relationship between the patient's degree of immunodeficiency after HSCT and the incidence of various complications that may occur. Early diagnosis of CNS complications is crucial for successful management and a good prognosis, and computed tomography and magnetic resonance imaging play an important role in achieving these goals. The global increase in the use of HSCT requires radiologists to be familiar with CNS complications, their relationship to the patient's immune status, and their imaging appearances. This article describes the clinical background of HSCT; reviews the incidence, causes, and timeline of brain complications in children who underwent allogenic HSCT; and identifies the characteristic imaging findings of these disorders. ^©RSNA, 2018.

Clinical Utility of Diffusion-Weighted Imaging in Spinal Infections

PURPOSE

Both laboratory markers and radiographic findings in the setting of spinal infections can be nonspecific in determining the presence or absence of active infection, and can lag behind both clinical symptoms and antibiotic response. Magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) has been shown to be helpful in evaluating brain abscesses but has not been commonly used in evaluating spinal infections. We aimed to correlate findings on DWI of the spine to results of microbiological sampling in patients with suspected spinal infections.

METHODS

Patients who underwent MRI with DWI for suspicion of spinal infections and microbiological sampling from 2002 to 2010 were identified and reviewed retrospectively in this institutional review board approved study. In addition to DWI, scans included sagittal and axial T1, fast-spin echo (FSE) T2, and post-gadolinium T1 with fat saturation. Regions of interest were drawn on apparent diffusion coefficient (ADC) maps in the area of suspected infections, and ADC values were correlated with microbiological sampling.

RESULTS

Of 38 patients with suspected spinal infections, 29 (76%) had positive microbiological sampling, and 9 (24%) had negative results. The median ADC value was 740 × 10^-6 mm²/s for patients with positive microbiological sampling and 1980 × 10^-6 mm²/s for patients with negative microbiological sampling (p < 0.001). Using an ADC value of 1250 × 10^-6 mm²/s or less as the cut-off value for a positive result for spinal infection, sensitivity was 66%, specificity was 88%, positive predictive value was 95%, negative predictive value was 41% and accuracy was 70%.

CONCLUSION

In patients with suspected spine infection, ADC values on DWI are significantly reduced in those patients with positive microbiological sampling compared to patients with negative microbiological sampling. The DWI of the spine correlates well with the presence or absence of spinal infection and may complement conventional magnetic resonance imaging (MRI).

Pyogenic Ventriculitis and Meningitis Caused by Streptococcus Acidominimus in Humans: A Case Report

Patient: Male, 49

Final Diagnosis: Pyogenic ventriculitis and meningitis caused by Streptococcus acidominimus

Symptoms: Confusion • fever • headache

Medication: —

Clinical Procedure: Antibiotics

Specialty: Infectious Diseases

Diagnosis of Meningitis Caused by Pathogenic Microorganisms Using Magnetic Resonance Imaging: A Systematic Review

Introduction:

Bacterial meningitis is an acute infectious inflammation of the protective membranes covering the brain. Its early diagnosis is vital because of its high morbidity and mortality. It is mostly diagnosed by a gold standard diagnostic tool i.e. Cerebrospinal Fluid (CSF) analysis. However, it is sometimes difficult and or impossible to do this procedure and an alternative diagnostic tool is needed. Contrast enhanced magnetic resonance imaging can detect the pus or other changes in subarachnoid space. But our optimal aim is to use an imaging method without using contrast to be useable and available in more specific condition.

Methods:

This study aimed to survey the role of non-contrast Magnetic Resonance Imaging (MRI) in the diagnosis of the bacterial meningitis. MEDLINE/PubMed Central, Web of Science and Scopus were searched without time period and language limitation until March 2017. We found 6410 papers in our initial search. After assessing the content of the papers based on Cochrane library guidelines and inclusion/exclusion criteria, 6 relevant studies were included in the systematic review. All of included studies were observational studies.

Results:

MRI studies demonstrated that Fluid Attenuation Inversion Recovery (FLAIR) and Diffusion-Weighted Image (DWI) MR imaging among all MRI modalities can detect some abnormalities compatible with bacterial meningitis. FLAIR and DWI-MR imaging are potentially useful to diagnose bacterial meningitis and can be used in emergent condition in which bacterial meningitis is highly suspicious and the other diagnostic tools are not available or feasible.

Primary pyogenic ventriculitis caused by Neisseria meningitidis: case report and review of the literature

Background. Pyogenic ventriculitis is a well-known complication of meningitis, brain abscesses and intraventricular drains. Primary pyogenic ventriculitis is a rare entity and few cases have been described so far. We report the first case of primary pyogenic ventriculitis in an adult caused by Neisseria meningitidis and present an overview of all reported adult primary pyogenic ventriculitis cases in the English literature.

Methods. A PubMed search was performed using the terms ependymitis, ventricular empyema, pyocephalus and ventriculitis. Filter was set for adults and English. Articles in which pyogenic ventriculitis was a complication of well-known risk factors were excluded. A total of five cases of primary pyogenic ventriculitis were identified.

Results. There were seven adult patients. Only one patient showed signs of meningeal irritation. Four patients had positive blood cultures with Escherichia coli (one patient), methicillin-resistant Staphylococcus aureus (one patient), one patient was bacteraemic with Enterococcus faecalis, Escherichia coli and Peptostreptococcus spp., and N. meningitidis (our patient). In four patients cerebrospinal fluid was sent for culture, which yielded methicillin-sensitive Staphylococcus aureus (one patient), Peptostreptococcus spp. (one patient), Streptococcus intermedius (one patient, identified via 16S PCR) and Listeria monocytogenes (one patient). Cerebrospinal fluid cell count was determined in four patients and showed pleocytosis in all four cases. Ventricular drainage was performed in four patients. Five patients survived.

Discussion. We report the first case of pyogenic ventriculitis caused by N. meningitidis. Primary pyogenic ventriculitis is a rare entity with various clinical presentations caused by various bacterial species. Treatment consists of adequate antimicrobial therapy, and ventricular drainage may be necessary.

The role of diffusion-weighted MRI in assessment of inflammatory bowel disease

AIM

To evaluate the role of diffusion-weighted MRI (DW-MRI) in detecting and differentiating acute from chronic bowel inflammation in patients with Crohn's disease (CD).

MATERIALS AND METHODS

MR-enteroclysis examinations with DW-MRI were reviewed from 24 patients with histologically proven CD. Segments of bowel were evaluated for acute and chronic inflammation in three different reviews of the MRI images: T2w alone, T2w + DWI, and T2w + CET1w. Mean ADC values of normal bowel segments, as well as bowel segments with acute and chronic inflammation were calculated and compared. Analyses of receiver-operating characteristic (ROC) curve were performed.

RESULTS

Hundred and forty four bowel segments in total were reviewed. Inflammation was present in 45 segments. Acute inflammation was present in 31 segments, chronic inflammation in 14. 98 bowel segments showed no inflammatory activity. Sensitivity and specificity for differentiation between normal and inflamed bowel segments was 0.6, 0.67, and 0.80 on T2w, T2w + DWI, and T2w + CET1w datasets, respectively. Specificities for differentiation between normal and inflamed bowel segments were 0.96, 0.96, and 0.98. Sensitivities for differentiation between acute and chronically inflamed bowel segments were 0.85, 0.91, and 0.96, and specificities were 0.88, 0.89, and 1.0, respectively. The mean ADC value of normal bowel (2.18 ± 0.37 × 10(-3) mm(2)/s) was statistically significantly greater than the mean value of inflamed bowel segments (p < 0.001). The mean ADC value of acutely inflamed bowel segments was statistically significantly lower than that of chronically inflamed bowel segments (1.09 ± 0.18 × 10(-3) vs. 1.55 ± 0.21 × 10(-3) mm(2)/s) (p < 0.001). Estimated area under the ROC curve for the diagnosis of acute vs. chronic inflammation was 0.950. A threshold of ADC value of 1.41 × 10(-3) mm(2)/s was optimal for calculation of sensitivity and specificity.

CONCLUSION

DW-MRI improves detection and differentiation of acute vs. chronic inflammatory changes of the bowel in patients with CD compared to T2w-images alone.

Diffusion-weighted MRI abnormalities in an outbreak of Streptococcus agalactiae Serotype III, multilocus sequence type 283 meningitis

PURPOSE

In 2015, an outbreak of group B streptococcal (GBS) infection caused by Streptococcus agalactiae Serotype III, multilocus sequence type 283, related to consuming infected raw freshwater fish, affected more than 200 patients in Singapore. We describe the clinical, laboratory, and neuroimaging features of a subgroup of adults with central nervous system (CNS) infections caused by GBS.

MATERIALS AND METHODS

The database of the Singapore Neurologic Infections Program (SNIP), a national multicenter study for surveillance of infectious neurologic disease, was reviewed to select patients with GBS CNS infection during the outbreak. Cases were diagnosed on the basis of clinical features, cerebrospinal fluid (CSF) findings and identification or isolation of Streptococcus agalactiae in the blood or CSF. Demographic, clinical and neuroradiological information was obtained prospectively and retrospectively abstracted.

RESULTS

Fourteen patients (6 male, 8 female; median age, 58 years) presented with fever, meningism, headache, encephalopathy, focal neurological deficits, and/or seizures. All except two were previously healthy. Diffusion-weighted imaging (DWI) on admission was abnormal in 13 patients, showing tiny hyperintensities in the subarachnoid space (7 patients), ventricles (6 patients) and brain parenchyma (8 patients); 5 patients had cerebellar abnormalities.

CONCLUSION

Among healthy non-pregnant adults infected with Serotype III, multilocus sequence type 283 GBS meningitis linked to eating infected raw freshwater fish, DWI detected small pus collections and unusual cerebellar involvement. A collaborative national surveillance system that includes MRI can be helpful during unusual food-borne zoonotic infectious disease outbreaks.

LEVEL OF EVIDENCE

4 J. Magn. Reson. Imaging 2017;45:507-514.

Primary Intraventricular Brain Abscess Resulting in Isolated Dilation of the Inferior Horn and Unilateral Hydrocephalus

Primary intraventricular brain abscesses are rare, and there are no established treatment guidelines for this condition. We report a case in which isolated ventricular dilatation and unilateral hydrocephalus developed after seemingly successful conservative management and which required surgical diversion of the cerebrospinal fluid. A 59-year-old woman presented to our emergency department with high-grade fever and headache. Brain magnetic resonance imaging (MRI) revealed abscesses in the bilateral posterior horn. Although surgical evacuation of the abscesses was considered, conservative management with antibiotics was selected because of the paucity of severe neurological deficits and the concern that an attempt to evacuate the intraventricular abscess might lead to inadvertent rupture of the abscess capsule and acute ventriculitis. Despite reduction in the abscess volume, the patient developed an altered mental status 4 weeks after admission. Follow-up MRI revealed isolated dilation of the left inferior horn, compressing the brainstem. Emergency fenestration of the dilated inferior horn was performed, and endoscopic observation revealed an encapsulated abscess with adhesion to the ventricular wall which was thought responsible for the ventricular dilation and unilateral hydrocephalus. Two weeks after the initial surgery, the unilateral hydrocephalus was treated by placement of a ventriculoperitoneal shunt. Eradication of the intraventricular brain abscesses without surgical evacuation may justify the conservative management of this patient. However, the possibility that earlier surgical evacuation might have prevented development of the isolated ventricular dilation cannot be denied. Additional clinical experience is required to determine which treatment (surgical vs. conservative) is more appropriate in patients with primary intraventricular brain abscesses.

Non-invasive detection of infection in acute pancreatic and acute necrotic collections with diffusion-weighted magnetic resonance imaging: preliminary findings

PURPOSE

The purpose of this study was to evaluate the contribution of diffusion-weighted magnetic resonance imaging (DW-MRI) to the detection of infection in acute pancreatitis-related collections.

METHODS

A total of 21 DW-MRI, and computed tomography (CT) were performed on 20 patients diagnosed as acute pancreatitis with acute peri-pancreatic fluid or necrotic collections. Collections were classified as infected or sterile according to the culture and follow-up results. Collections with gas bubbles on CT images were considered to be infected. Collections with peripheral bright signals on DW-MRI images were considered to be positive, whereas those without signals were considered to be negative. Apparent diffusion coefficient (ADC) values of the peripheral and central parts of the collections were measured. Student's t test was used to compare the means of ADC values of independent groups.

RESULTS

Apart from one false positive result, the presence of infection was detected by DW-MRI with 95.2% accuracy. The sensitivity and accuracy of DW-MRI were higher than CT for the detection of infection. The ADC values in the central parts of the collections were significantly different between the infected and sterile groups.

CONCLUSION

DW-MRI can be used as a non-invasive technique for the detection of infection in acute pancreatitis-associated collections.

[Pathognomonic magnetic resonance imaging (MRI) finding of fluid-fluid level in pyogenic ventriculitis: two case reports]

Pyogenic ventriculitis is an uncommon and potentially fatal central nervous system infection. Delayed treatment due to non specific clinical symptoms may lead to an unfavorable outcome. Brain magnetic resonance imaging (MRI) plays an important role in the diagnosis of pyogenic ventriculitis. We describe two patients with pyogenic ventriculitis presenting with a pathognomonic MRI finding. The first patient, a 77-year-old female, developed high fever and consciousness disturbance. MR images revealed hyperintense lesions with a fluid-fluid level in the bilateral lateral ventricles on diffusion-weighted images (DWIs) and hypointense lesions on T2-weighted images (T2WIs). MR images also revealed findings of left otitis media. The second patient, a 63-year-old male, who had a past history of multiple myeloma and had received chemotherapy, developed high fever and left hemiparesis. MR images revealed a hyperintense lesion with a fluid-fluid level in the right lateral ventricle on DWIs and a hypointense lesion on T2WIs, multiple ring-enhancing lesions on gadolinium enhanced T1-weighted images, and pontine infarction on DWIs. Chest computed tomography revealed an infiltrative shadow in the lower lobe of the left lung. On the basis of MRI findings, both patients were diagnosed as having pyogenic ventriculitis and were administered high-dose meropenem intravenously. The second patient was also administered sulfamethoxazole-trimethoprim orally. Intraventricular abnormalities disappeared and the patients achieved complete remission after the antibacterial treatment. Intraventricular hyperintense lesions on DWIs and hypointense ones on T2WIs with a fluid-fluid level is a pathognomonic finding of pyogenic ventriculitis and has not been previously reported in other diseases. Recognition of the characteristic MRI features and initiation of high-dose and appropriate antibiotics in an early stage may lead to a favorable outcome of the disease.

Clinico-radiological features of subarachnoid hyperintensity on diffusion-weighted images in patients with meningitis

AIM

To investigate the clinical and radiological features of meningitis with subarachnoid diffusion-weighted imaging (DWI) hyperintensity.

MATERIALS AND METHODS

The clinical features, laboratory data, and radiological findings, including the number and distribution of subarachnoid DWI hyperintense lesions and other radiological abnormalities, of 18 patients seen at five institutions were evaluated.

RESULTS

The patients consisted of eight males and 10 females, whose ages ranged from 4 months to 82 years (median 65 years). Causative organisms were bacteria in 15 patients, including Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus agalactiae, Staphylococcus aureus, Klebsiella pneumoniae, and Listeria monocytogenes. The remaining three were fungal meningitis caused by Cryptococcus neoformans. Subarachnoid DWI hyperintense lesions were multiple in 16 of the 18 cases (89%) and predominantly distributed around the frontal lobe in 16 of the 18 cases (89%). In addition to subarachnoid abnormality, subdural empyema, cerebral infarction, and intraventricular empyema were found in 50, 39, and 39%, respectively. Compared with paediatric patients, adult patients with bacterial meningitis tended to have poor prognoses (7/10 versus 1/5; p = 0.1).

CONCLUSION

Both bacterial and fungal meningitis could cause subarachnoid hyperintensity on DWI, predominantly around the frontal lobe. This finding is often associated with poor prognosis in adult bacterial meningitis.

MR imaging of neonatal brain infections

Infections of the brain in the postnatal period differ from those in older children as a result of a combination of distinct epidemiologic factors in general, and immaturity of neonatal brain and immunologic host response in particular. It has been recognized that clinical and neurologic signs are often nonspecific, sometimes scarce, and seldom correlate with the extent of neuroimaging findings, thus warranting an early MR imaging examination in the course of the disease, enabling rapid therapy institution and better clinical outcome. This article reviews most of postnatal pathogen agents involved in neonatal brain infections, related physiopathology, and neuroimaging findings.

Diffusion-weighted MRI: role in detecting abdominopelvic internal fistulas and sinus tracts

PURPOSE

To retrospectively determine the incremental value of diffusion-weighted MR-imaging (DW-MRI) to T2-weighted (T2w) images in diagnosis of internal fistulas (IFs) and sinus tracts (STs).

MATERIALS AND METHODS

Fourteen patients with 25 IFs and STs arising from the small bowel (20), colon (4) and biliary tract (1) were included. Two independent observers reviewed T2w images, T2w+DW-MRI images and T2w+contrast enhanced T1-weighted (CE T1w) images at three sessions to detect IF/ST based on a confidence scale of five. Sensitivity and confidence score of each session was compared.

RESULTS

10/25 (40%) and 9/25 (36%) IFs and STs were detected on T2w images by observer 1 and 2, respectively. Both observers detected 19/25 (76%) and 24/25(96%) IFs and STs on T2w+DW-MRI and T2w+CE T1w images, respectively. Detection rate and confidence score improved significantly by combining T2w images with DW-MRI or CE T1w images (reader 1 + 2: P ≤ 0.01). There was no significant difference between the IF/ST detection rate of T2w+DW-MRI and T2w+CE T1 image combinations. Confidence scores with T2w+CE T1w images were significantly greater than DW-MRI+T2w images (reader 1:P = 0.01; reader 2: P = 0.03).

CONCLUSION

DW-MRI showed additional value to T2w imaging for diagnosis of IF and ST. DW-MRI can be a useful adjunct, especially for patients with renal failure.

Diffusion MR imaging for monitoring treatment response

The objective of this article was to emphasize the use of diffusion-weighted imaging in the diagnosis and follow-up of several major disease contexts, as established in recent literature. In some of these diseases the diffusion changes are correlated with the clinical deficit and are potentially useful for early diagnosis and longitudinal evaluation, as well as in the context of pharmacologic trials. Diffusion magnetic resonance is a major advance in the continuing evolution of MR imaging. It provides contrasts and characterization between tissues at a cellular level that may imply differences in function as well as framework and have contributed to a better understanding of the pathophysiological mechanisms of several diseases.

Diffusion imaging in brain infections

Diffusion-weighted magnetic resonance imaging (DWI) provides image contrasts that are different from conventional magnetic resonance techniques. DWI is particularly sensitive for detecting acute ischemic stroke, but it also has many other clinical applications, including the evaluation of central nervous system (CNS) infections. This article addresses the role of DWI in the differential diagnosis of CNS infections, and discusses the most common DWI findings for each type of infection.

The art and science of straight lines in radiology

OBJECTIVE

The purpose of this article is to review the physical basis for straight radiographic lines, identify the possible components that may form a straight line interface in the body, provide illustrative examples across multiple organ systems and modalities, and explore how the detection of these interfaces can support specific diagnoses.

CONCLUSION

Detection of a straight line interface can help the radiologist recognize otherwise difficult or subtle pathologic processes, and identification of its components can provide valuable clues to diagnosis.