Majda M. Thurnher

Intradural spinal tumors: current classification and MRI features

The differential diagnosis of intradural spinal tumors is primarily based on location, but the clinical presentation, age, and gender of the patient are also important factors in determining the diagnosis. This comprehensive review focuses on the current classification, clinical symptoms, and MRI features of the more common intradural extramedullary and intramedullary neoplastic lesions. This review does not include extradural lesions.

Diffusion-weighted imaging, diffusion-tensor imaging, and fiber tractography of the spinal cord.

In the brain, diffusion-weighted imaging (DWI) is an established and reliable method for the characterization of neurologic lesions. Although the diagnostic value of DWI in the early detection of ischemia has not diminished with time, many new clinical applications of DWI have also emerged. Diffusion-tensor imaging and fiber tractography have more recently been developed and optimized, allowing quantification of the magnitude and direction of diffusion along three principal eigenvectors. Diffusion-tensor imaging and fiber tractography are proving to be useful in clinical neuroradiology practice, with application to several categories of disease, and to be a powerful research tool. This article describes some of the applications of DWI and diffusion-tensor imaging in the evaluation of the diseases of the spinal cord.

Primary central nervous system lymphoma in AIDS: a wider spectrum of CT and MRI findings

Abstract Diagnosis of primary central nervous system lymphoma (PCNSL) in patients with AIDS based on radiological findings is still a challenging problem. Our purpose was to review the CT and MRI findings in PCNSL in our patients with AIDS and compare them with those reported in the literature. CT and MRI of 28 patients with AIDS and pathologically confirmed PCNSL were analysed retrospectively for the number of lesions, their site, size, density, signal intensity, contrast enhancement, oedema and mass effect. We found 82 lesions. On CT 45 lesions were found in 22 patients, whereas MRI revealed 66 in 20 patients. The lymphoma was solitary in 20 patients (29 %) and multiple in 20 (71 %). Spontaneous haemorrhage was seen in 7 patients. Contrast-enhanced MRI showed no enhancement in 27.3 % (18/66) of the lesions. In one patient diffuse signal abnormalities in the white matter were seen on T2-weighted images. Our findings suggest that the previously described spectrum imaging characteristics of PCNSL has widened. Neuroradiologists should be aware of the variable appearance in patients with AIDS. Spontaneous haemorrhage, a nonenhancing lesion, or diffuse white matter changes do not exclude lymphoma in an immunocompromised patient.

Covered self-expanding transhepatic biliary stents: Clinical pilot study

PurposeWe report our preliminary results with a new type of self-expanding covered stent for treatment of malignant biliary obstruction.MethodsWallstents, fully covered with high elasticity polyurethane, with an unconstrained diameter of 10 mm and a total length of 69 mm, were placed transhepatically under fluoroscopic guidance in five patients. The length of the biliary obstruction varied between 30–50 mm. At 1 and 3 months (82–98 days) clinical assessment, serum bilirubin measurement, and ultrasound examination of the biliary tree were performed.ResultsInitial uncomplicated deployment of the stents and internal drainage was possible in all patients. Distal stent migration resulted in early biliary reobstruction in one patient. At 3-month follow-up, partial reobstruction, most probably due to sludge formation, was found in another patient.ConclusionOur initial results indicate that the covered, self-expanding Wallstent endoprosthesis can be reliably and safely deployed transhepatically for malignant biliary obstruction.

Analysis of the utility of diffusion-weighted MRI and apparent diffusion coefficient values in distinguishing central nervous system toxoplasmosis from lymphoma

IntroductionToxoplasmosis and lymphoma are common lesions of the central nervous system in patients with AIDS. It is often difficult to distinguish between these lesions both clinically and radiographically. Previous research has demonstrated restricted diffusion within cerebral lymphomas and bacterial abscesses. However, little work has been done to evaluate the diffusion characteristics of toxoplasmosis lesions. This study was designed to explore further the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps and values in making the distinction between toxoplasmosis and lymphoma.MethodsThe magnetic resonance imaging (MRI) studies of 36 patients, including 22 with toxoplasmosis (all of whom had AIDS) and 14 with lymphoma (8 of whom had AIDS), at two institutions were reviewed retrospectively. The characteristics of the lesions on DWI were evaluated, and the ADC ratios of the lesions were calculated and compared.ResultsThere was significant overlap of the ADC ratios of toxoplasma and lymphoma, most notably in the intermediate (1.0–1.6) range. There was variability in ADC ratios even among different lesions in the same patient. In only a minority of the lymphoma patients were the ADC ratios low enough to suggest the correct diagnosis.ConclusionOur study showed that toxoplasmosis exhibits a wide spectrum of diffusion characteristics with ADC ratios which have significant overlap with those of lymphoma. Therefore, in the majority of patients, ADC ratios are not definitive in making the distinction between toxoplasmosis and lymphoma.

Intracranial infections : Clinical and imaging characteristics

The radiologist plays a crucial role in identifying and narrowing the differential diagnosis of intracranial infections. A thorough understanding of the intracranial compartment anatomy and characteristic imaging findings of specific pathogens, as well incorporation of the clinical information, is essential to establish correct diagnosis. Specific types of infections have certain propensities for different anatomical regions within the brain. In addition, the imaging findings must be placed in the context of the clinical setting, particularly in immunocompromised and human immunodeficiency virus (HIV)-positive patients. This paper describes and depicts infections within the different compartments of the brain. Pathology-proven infectious cases are presented in both immunocompetent and immunocompromised patients, with a discussion of the characteristic findings of each pathogen. Magnetic resonance spectroscopy (MRS) characteristics for several infections are also discussed.

Progressive multifocal leukoencephalopathy in AIDS: initial and follow-up CT and MRI

Abstract We sought to determine the value of follow-up CT and MRI in patients with acquired immunodeficiency syndrome (AIDS) and progressive multifocal leukoencephalopathy (PML). We reviewed 50 CT and 19 MRI examinations performed in 21 biopsy- or autopsy-proven cases of PML; 17 patients had follow-up examinations (mean time 5.9 weeks). The radiological examinations were correlated with pathological findings at autopsy. On initial imaging studies, 73 lesions were found. On follow-up, the most striking feature was rapid progression in both size and number of the lesions (from a mean of 3.2 to 6.9 per patient). One third of the patients showed increasing mass effect. A central area suggesting necrosis, of variable size, was found in 12/16 patients. Autopsy revealed macroscopic necrotic changes in the lesions in 11/16 patients.

Imaging in acute stroke

Stroke is a syndrome characterized by a sudden neurological deficit caused by intracranial hemorrhage or ischemia. Computed tomography (CT) maintains a primary role in the evaluation of patients with acute stroke. The optimal magnetic resonance imaging (MRI) protocol in acute stroke includes diffusion-weighted imaging (DWI) to show acute ischemic lesion and MR perfusion study to estimate brain perfusion. Careful selection of patients for a thrombolytic therapy is crucial to improve safety and efficacy.

Neuroimaging evaluation of non-accidental head trauma with correlation to clinical outcomes: a review of 57 cases.

OBJECTIVE To review the clinical presentation and neuroimaging findings in patients with high clinical suspicion for non-accidental trauma (NAT) of the head, to investigate associations between imaging findings and long-term neurologic outcome in abused children. STUDY DESIGN A retrospective review of 57 cases of NAT of the head from a single institution was performed. Neuroimaging studies (computed tomography [CT] and magnetic resonance imaging [MRI]) were reviewed by a senior neuroradiologist, a neuroradiology fellow, and a radiology resident. Clinical history and physical findings, including retinal examination, imaging, and follow-up assessment, were reviewed. RESULTS The mean time between the patients arrival at the hospital and CT and MRI imaging was 2.9 hours and 40.6 hours, respectively. The most common clinical presentation was mental status changes, seen in 47% of patients. The most common neuroimaging finding was subdural hematoma, seen in 86% of patients. In the 47 patients who underwent both MRI and CT, 1 case of suspected NAT was missed on head CT. CT detected signs of global ischemia in all 11 patients who died (mean time after arrival at the hospital until undergoing CT, 1.1 hours). MRI detected additional signs of injury in patients who developed mild to moderate developmental delay. CONCLUSION CT was able to detect evidence of NAT of the head in 56 of 57 abused children included in our cohort and predicted severe neurologic injury and mortality. MRI was useful in detecting additional evidence of trauma, which can be helpful in risk stratification for neurologic outcomes as well in providing confirming evidence of repeated injury.

Magnetic resonance imaging spectrum of medulloblastoma.

IntroductionTwo medulloblastoma variants were recently added to the WHO classification of CNS tumours. We retrospectively analysed the imaging findings of 37 classic and 27 cases of variant medulloblastomas to identify imaging characteristics that might suggest a particular MB subtype.MethodsSixty-four patients from three institutions were included. Location, tumour margins, signal intensities on conventional MRI, enhancement pattern, the presence of haemorrhage, calcifications and hydrocephalus were recorded and analysed. Signal characteristics on diffusion-weighted MR images and MR spectra were evaluated when available.ResultsThirty-seven classic type of MB (CMB), twelve cases of desmoplastic/nodular medulloblastoma (DMB), nine medulloblastomas with extensive nodularity (MB-EN), five cases of anaplastic and one of large-cell medulloblastoma were included. Fifty of 64 tumours were located in the 4th ventricle region. On T2WI, CMB were all hyperintense, whereas DMB and MB-EN showed isointensity in up to 66%. One third of the classic MB showed only subtle marginal or linear enhancement. All medulloblastoma variants showed marked enhancement.ConclusionThe results of our study suggest: (a) an age-dependent distribution of MB variants, with DMB and MB-EN more common in younger children; (b) a female predominance in DMB; (c) a more common off-midline location in DMB (50%) and MB-EN (33%) variants.