Structural and functional effects of metastases in rat brain determined by multimodal MRI

Metastasis to the brain results in significant impairment of brain function and poor patient survival. Currently, magnetic resonance imaging (MRI) is under‐utilised in monitoring brain metastases and their effects on brain function. Here, we sought to establish a model of focal brain metastasis in the rat that enables serial multimodal structural and functional MRI studies, and to assess the sensitivity of these approaches to metastatic growth. Female Berlin–Druckrey‐IX rats were injected intracerebrally with metastatic ENU1564 cells in the ventroposterior medial nucleus (VPM) of the thalamus, a relay node of the whisker‐to‐barrel cortex pathway. Animals underwent multimodal structural and vascular MRI, as well as functional MRI of the cortical blood oxygenation level dependent (BOLD) responses to whisker pad stimulation. T₂, diffusion, magnetisation transfer and perfusion weighted MRI enabled differentiation between a central area of more advanced metastatic growth and penumbral regions of co‐optive perivascular micrometastatic growth, with magnetisation transfer MRI being the most sensitive to micrometastatic growth. Areas of cortical BOLD activation in response to whisker pad stimulation were significantly reduced in the hemisphere containing metastases in the VPM. The reduction in BOLD response correlated with metastatic burden in the thalamus, and was sensitive to the presence of smaller metastases than currently detectable clinically. Our findings suggest that multimodal MRI provides greater sensitivity to tumour heterogeneity and micrometastatic growth than single modality contrast‐enhanced MRI. Understanding the relationships between these MRI parameters and the underlying pathology may greatly enhance the utility of MRI in diagnosis, staging and monitoring of brain metastasis.     

Dural sinus thrombosis presenting as unilateral lobar haematomas with mass effect: An easily misdiagnosed cause of cerebral haemorrhage

Dural sinus thrombosis has protean clinical and radiological manifestations ranging from minimal effacement of sulci with no symptoms to severe haemorrhagic infarcts associated with focal deficits, coma and even death. An uncommon form of presentation is characterized by unilateral lobar haemorrhage associated with extensive oedema and parenchymal distortion. In an acute presentation, this might resemble haemorrhage into a tumour. In delayed presentations, the haematoma, being iso‐ or hypodense and showing peripheral ring‐like enhancement, can mimic aggressive tumours or infective processes. As this is an uncommon condition, misdiagnosis is common with the potential for mismanagement and adverse outcomes. We present five such consecutive cases that were initially misdiagnosed as other entities. Each of these cases on closer inspection show features observed on CT and MRI that should have suggested a diagnosis of dural venous sinus thrombosis. One of these cases progressed to not only extensively involve the superficial sinuses but also the deep veins, with a significant adverse outcome. The imaging features of this interesting variant of dural sinus thrombosis are reviewed. The haemodynamic basis for haemorrhage and anatomical basis for the lateralization of the lesions are discussed.     

血液病相关颅内出血的临床和影像学特点分析

 目的　分析血液病相关颅内出血（ICH）的临床和影像学特点,提高临床医师的认识。方法　1998年1月至2010年5月发生的与原发血液病相关的ICH病例31例,回顾性分析其基础疾病、临床和影像学表现以及导致死亡的危险因素。结果　发生ICH的血液病以急性髓细胞白血病（AML）、特发性血小板减少性紫癜（ITP）多见,分别为13例和6例,多表现为头痛、烦躁、恶性呕吐和意识障碍,缺乏定位体征,影像学表现以渗血为主,CT与MRI诊断的符合率为60 %（3／5）,头颅MRI的ICH检出率高于CT。总病死率为71 %（22／31）,发热、白细胞＞5×109／L、血小板＜50×109／L、免疫球蛋白增高、凝血功能异常、全身多部位出血等是ICH的危险因素,具备≥2个危险因素者病死率为86.4 %（19／22）,显著高于有≤1个危险因素的患者病死率[33.3 %（3／9）]（χ2＝8.718,P＝0.003）。结论　血液病相关ICH是威胁患者生命的严重并发症,头颅MRI有助于提高血液病相关ICH诊断率,发热、白细胞＞5×109／L、血小板＜50×109／L、免疫球蛋白增高、凝血功能异常等多种危险因素并存可导致血液病ICH患者死亡率增加。     

M.R.I. Spectrum of Intrinsic Spinal Cord Lesions

We report our experience of 42 patients undergoing magnetic resonance imaging (MRI) studies demonstrating intrinsic lesions of the spinal cord, excluding those secondary to spondylosis, trauma or congenital malformations. Histological confirmation of the radiological diagnosis was obtained in 15 (36%). MRI is more sensitive than either myelography or CT. MRI identified a previously non-visualised lesion in 17 of 30 cases. In a further 13 cases, MRI contributed by identifying associated features such as cysts and haemorrhage which have aided in the diagnosis and management of the patients. The last 12 cases, which were patients with multiple sclerosis, had MRI as the only neuroradiological examination. These illustrate a range of appearances. The overlap of imaging appearances of the various pathologies implies that a useful diagnosis and differential can only be offered by considering the MRI appearances of a lesion, with its associated features, with the clinical presentation, and with other imaging modalities where appropriate.     

Radiologische Diagnostik zerebraler Metastasen

Background

Imaging plays a key role in the diagnosis of central nervous system (CNS) metastases.

Objective

In this review the role of magnetic resonance imaging (MRI) and computed tomography (CT) in the work-up of cerebral metastases is presented. In addition to characteristic imaging findings technical aspects for improved detection of CNS metastases and differential diagnoses are shown.

Material and methods

This review is based on own experience and relevant recent publications.

Results

In the diagnosis of CNS metastases contrast-enhanced MRI is the radiological method of choice. The sensitivity can be further increased by increasing contrast medium dose as well as the use of various magnetization transfer techniques. Functional MRI techniques, such as magnetic resonance spectroscopy, perfusion and diffusion-weighted imaging, diffusion tensor imaging and dynamic contrast-enhanced imaging can further improve the differential diagnosis and detection of recurrent disease. If CT is used for diagnostics of cerebral metastases it should be performed with increased contrast combined with a scan delay.

Conclusions

Contrast-enhanced MRI ideally using a multimodal protocol is the most sensitive method for the detection of CNS metastases and should therefore be preferred to CT.     

Abdominal manifestations of cystic fibrosis in adults: A review

Gastrointestinal manifestations of disease are present in most adults with cystic fibrosis. Radiologists are familiar with the classical imaging characteristics of end‐stage pulmonary disease and the radiological findings of meconium ileus in neonates. As most patients now live into adulthood, recognition of the imaging appearances of abdominal disease is important to enable prompt diagnosis and treatment. Accordingly, this article presents typical imaging appearances of the adult gastrointestinal manifestations of cystic fibrosis.     

MRI of sporadic Creutzfeldt-Jakob disease

The key MRI findings in five cases of sporadic Creutzfeldt-Jakob disease (CJD) are illustrated with four 'definite' and one 'probable' according to World Health Organization criteria. Close attention to fluid-attenuation inversion recovery and diffusion-weighted imaging sequences are important for diagnosis, noting especially restricted diffusion in cortical and deep grey matter. Our study and those of others show predominant cortical, caudate and thalamic involvement. This pattern is highly sensitive and specific for the diagnosis. Fluid-attenuation inversion recovery and diffusion-weighted imaging signal abnormality becomes progressively more extensive and bilateral as disease progresses, but may become less pronounced in end-stage disease because of atrophy.     

Cystic lumbar nerve sheath tumours: MRI features in five patients

Intraspinal cystic lumbar nerve sheath tumours constitute an uncommon subset of tumours with distinct clinico‐biological behaviour. The MRI findings in five such cases are presented. Four of these were cystic schwannomas and one was a cystic neurofibroma. The pathology, MRI findings and the differential diagnosis of these rare tumours are analysed.     

Multiples Myelom

Multiple myeloma first shows alterations in conventional X-ray images at later stages and can be seen as coarse strands of osteoporosis with infiltration of the vertebrae or localized osteolysis. The slice imaging technique does not suffer from overlapping images and smaller osteolytic changes can therefore be recognized earlier using computed tomography (CT). CT is also very well suited for detection of skeletal structures at risk for fractures. In the region of the long bones infiltration of the medullary cavity can be found with or without destruction of the cortical substance. Magnetic resonance imaging (MRI) is the most sensitive method to visualize manifestations of the bone marrow by multiple myeloma. The total vertebral column and the pelvis should always be imaged as these are the main locations of manifestations of multiple myeloma. If possible whole body MRI should be carried out because this is more sensitive than conventional X-rays and CT. MRI also is of value for the prognosis. The guidelines of the International Myeloma Foundation should be used for staging.     

Imaging and intervention of retroperitoneal fibrosis

Retroperitoneal fibrosis is a rare condition characterized by the development of fibrous plaques in the retroperitoneal space. The fibrous plaques characteristically arise distal to the bifurcation of the abdominal aorta and progress to encase the iliac vessels distally and are defined by the associated encasement of one or both ureters. Imaging plays an important role in not only establishing the diagnosis, but also in monitoring disease progression. Historically, the radiological diagnosis was made predominantly by intravenous urography and retrograde pyelography. More recently, advances in cross‐sectional imaging with ultrasound and contrast‐enhanced CT have allowed for a more precise diagnosis as well as helping to accurately define the extent of the disease. At our institution, we have found ultra‐fast MRI to also play a useful role in establishing the diagnosis. In particular, magnetic resonance urography using HASTE (half Fourier‐acquired single shot turbo spin‐echo) sequences allow a safe alternative to intravenous urography, particularly in patients with poor renal function. The purpose of this article is to describe the role of the various imaging methods available to the radiologist and to emphasize the important role that the interventional radiologist now plays, not only in obtaining tissue for diagnosis, but also in providing treatment of the disease by percutaneous nephrostomy drainage and subsequent stent placement in select cases.     

Combined diagnostic and therapeutic imaging in the diagnosis of venous sinus thrombosis in postpartum patients

The case of a woman on day four post partum with sensorimotor deficit of the right side and CT evidence of a left temporofrontal hemorrhagic lesion, is presented. Attending physicians requested cerebral angiography. To better evaluate the clinical justification of requested imaging procedure the patient medical history and performed CT examination were carefully revised. According to this analysis and based on a clinicoradiological methodology, the request of a cerebral angiography was considered appropriate. The examination showed several radiological signs but a definitive diagnosis could not be established. Second choice imaging procedures were analyzed and MRI completed with MR-angiography was performed. It allowed to document transverse and sigmoid sinus thrombosis. Therefore, in the diagnosis of venous sinus thrombosis, MRI combined with MR-angiography was shown to be a method of first choice while angiography plays a major role in therapy for intravascular thrombolysis.     

CT perfusion in acute stroke calls: A pictorial review and differential diagnoses

CT perfusion is increasingly utilised in hyperacute stroke to facilitate diagnosis and patient selection for reperfusion therapies. This review article demonstrates eight examples of how CT perfusion can be used to diagnose stroke mimics and small volume infarcts, which can be easily missed on non‐contrast CT, and to suggest the presence of an ischaemic penumbra. Radiologists involved in stroke management must understand the importance of rapid imaging acquisition and be confident in the prospective interpretation of this powerful diagnostic tool as we move into a new era of hyperacute stroke care.     

Diagnostic challenges,management and outcomes of midline low-grade gliomas

Introduction

Low-grade gliomas (LGGs) are slow-growing and diffusely infiltrating tumours constituting 25–30 % of adult gliomas. Rarely, these tumours may arise in the cerebral midline, including the thalamus, hypothalamus, tectum and brainstem. Here we present a contemporary experience with midline LGGs.

Methods

Midline LGGs were identified from a retrospective database of adult patients who received a histological diagnosis of WHO grade II glioma between 2006 and 2012 at a single institution. Location, radiological data and clinical outcomes were collected. IDH1 status was assessed by immunohistochemistry.

Results

Eighteen patients with midline LGGs were identified, with a median age of 45. Most received biopsy upon diagnosis, though asymptomatic patients with tectal tumours underwent active surveillance. Oligodendroglial tumours were much less common than in a comparable group of lobar tumours (6 vs. 38 %, Fisher’s exact test, p = 0.007). Only one tumour was immunopositive for IDH1 (1/17). Radiological diagnosis correlated with histology in only 71 % of patients. Median survival of midline LGGs was 48 months (3–90 months) and radiological features such as contrast enhancement, size and radiological diagnosis did not predict survival in this cohort. Median overall survival of midline LGGs was less than lobar LGGs (log-rank, p = 0.006), though differences became insignificant when considering only biopsied astrocytomas in both locations (log-rank, p = 0.491).

Conclusions

Diagnosis of midline LGGs is complicated by both limitations of biopsy and imaging. Midline tumours have a poorer prognosis compared to lobar equivalents and survival differences are probably due to the absence of significant surgical intervention in midline locations.     

Hemimegalencephaly with tuberous sclerosis: A longitudinal imaging study

Hemimegalencephaly is a rare cerebral malformation characterized by asymmetry of the hemispheres and cortical dysplasias. We report clinical and imaging findings in a child with hemimegalencephaly involving the right cerebral hemisphere with associated manifestations of tuberous sclerosis complex. Gross abnormal myelination pattern and gyral abnormalities were seen in the enlarged hemisphere. Subsequent scans showed atrophy of the frontoparietal region in the enlarged hemisphere and normal growth of the opposite hemisphere exceeding the size of the abnormal hemisphere in the frontoparietal region. A few white‐matter lesions that were seen in the normal hemisphere on neonatal scan were difficult to appreciate on subsequent MR studies. The white‐matter lesions were better seen in the neonatal period, whereas cortical tubers were better detected at a later age.     

Imaging in multiple sclerosis: A new spin on lesions

This article evaluates the most relevant state‐of‐the‐art magnetic resonance (MR) techniques that are clinically available to investigate multiple sclerosis (MS). The presence of hypo‐ and hyperintense lesions on T1‐ and T2‐weighted magnetic resonance imaging (MRI) sequences in white matter (WM) is a common finding that is occasionally a diagnostic challenge for the radiologist. The technical requirements and how they may help to understand, classify or follow‐up these pathologies are briefly summarized. The gold standard for MS diagnosis is pathological correlation. Yet due to limited availability of biopsy and autopsy material, there is a high demand for imaging as a diagnostic as well as prognostic indicator. With the progress in MRI during the last decade, MRI now plays a leading role in the diagnosis and follow‐up of MS. A number of correlative pathological and MR studies have helped to define pathological substrates of MS in focal lesions and normal appearing white matter (NAWM). Vascular spaces mimicking MS lesions have been minimized by the enhanced differentiation of WM and grey (GM) matter parenchyma. The aim of this article is to enhance the current understanding of histopathology and radiological characteristics of MS lesions in space and time.     

Differentiating surgical from non-surgical lesions using perfusion MR imaging and proton MR spectroscopic imaging

Advanced MRI techniques, such as MR spectroscopy, diffusion and perfusion MR imaging can give important in vivo physiological and metabolic information, complementing morphologic findings from conventional MRI in the clinical setting. Combining perfusion MRI and MR spectroscopy can help in patients with brain masses in who the pre-operative differential diagnosis is unclear. This review demonstrates the use of dynamic, susceptibility weighted, contrast-enhanced MR imaging (DSC MRI) and magnetic resonance spectroscopic imaging (MRSI) to distinguish surgical from non-surgical lesions in the brain. There is overlap in the MRI appearance of many enhancing and ring-enhancing lesions such as gliomas, metastases, inflammatory lesions, demyelinating lesions, subacute ischemia, abscess and some AIDS related lesions. We review examples of histopathologically confirmed high-grade glioma, a middle cerebral artery territory infarct, a tumefactive demyelinating lesion and a metastasis for which conventional MR imaging (MRI) was non-specific and potentially misleading and demonstrate how DSC MRI and MRSI features were used to increase the specificity of neurodiagnosis. At several institutions, many patients routinely undergo MRI as well as MRSI and DSC MRI. Cerebral blood flow (CBF), mean transit time (MTT), and relative cerebral blood volume (rCBV) measurements are obtained from regions of maximal perfusion as determined from perfusion color overlay maps. Metabolite levels and ratios are determined for Choline (Cho), N-Acetyl Aspartate (NAA), Lactate and Lipids (LL). Metabolite levels are obtained by measuring the peak heights of each metabolite and the ratios are obtained from these measurements for Cho/Cr, Cho/NAA and NAA/Cr. Neurosurgical intervention carries substantial morbidity, mortality, financial and potential emotional cost to the patient and family. Making a pre-operative diagnosis allows the neurosurgeon to be confident in the choice of treatment plan for the patient and allays considerable patient anxiety. The utility of combining clinical findings with multi-parametric information from perfusion and spectroscopic MR imaging in differentiating surgical lesions from those which do not require surgical intervention is discussed.     

Performance of magnetic resonance imaging in pulmonary fungal disease compared to high‐resolution computed tomography

To evaluate the performance of magnetic resonance imaging (MRI) compared to computed tomography (CT) in patients diagnosed with pulmonary mycosis. We prospectively included 21 patients diagnosed with pulmonary mycosis between January 2013 and October 2014. Inclusion criteria were presence of respiratory symptoms, histopathological diagnosis of mycosis and absence of mycosis treatment. Reviewers identified one predominant imaging pattern per patient: nodular, reticular or airspace pattern. Afterwards, all CT findings were analysed separately per lobe and compared to MRI. Nodular pattern was the most common found (CT: 76.20%; MRI: 80.96%), followed by airspace pattern (CT and MRI: 9.52%) and reticular (CT: 9.52%; MRI: 4.76%). Compared to CT, MRI performance varied according to radiological finding and pulmonary region. For nodules, MRI presented high sensitivity (100% [95% CI: 93.52‐100]) and specificity (100% [95% CI: 92.00‐100]). For bronchiectasis and septal thickening, there were poorer positive predictive values (33.33% [95% CI: 1.77‐87.47]; and 83.33% [95% CI: 50.88‐97.06] respectively). As specificity and negative predictive value had superior results than sensitivity and positive predictive value, rather than for diagnosis of this condition, MRI might be more considered for the follow‐up of patients with pulmonary mycosis, an alternative to multiple radiation exposures with CT follow‐up.     

Imaging features of immunoglobulin G4‐related disease

Immunoglobulin G4‐related disease (IgG4‐RD) is a fibroinflammatory condition that was first recognised as a systemic disease in 2003, when patients with autoimmune pancreatitis were found to have extrapancreatic manifestations. Since 2003, IgG4‐RD has been described in a diverse range of other organs including the biliary tree, orbits, lacrimal glands, salivary glands, lungs, kidneys, aorta, retroperitoneum, lymph nodes, pachymeninges, prostate and pituitary gland. The disease frequently occurs in the absence of pancreatic involvement. The imaging manifestations of IgG4‐RD are broad and variable depending on the organ involved. The majority of individual organ appearances are non‐specific and differentiation between IgG4‐RD and potentially more serious conditions is not usually possible based on radiological findings in one organ alone. However, if there are simultaneous findings typical of IgG4‐RD in multiple organs then this is a key diagnostic clue and IgG4‐RD should be considered as one of the main differentials. This review article examines the spectrum of imaging appearances of IgG4‐RD. Increased awareness of the spectrum of radiological appearances of IgG4‐RD throughout the body and subsequent consideration of the condition may potentially avoid invasive treatment and lead to more prompt corticosteroid therapy.     

Morphologic magnetic resonance imaging features of therapy-induced cerebral necrosis

To describe the morphologic magnetic resonance imaging (MRI) findings in histologically proven therapy-induced cerebral necrosis. We retrospectively reviewed the morphologic MRI findings in patients with therapy-induced cerebral necrosis. Images were reviewed for size, location, and characteristics of signal intensity abnormalities and T1-contrast enhancement. Images were also assessed for mass effect, necrosis, cyst, atrophy, cortical thinning, and leukoencephalopathy. The individual imaging characteristics were correlated with clinical and treatment variables. There were 44 patients. Seventy percent had a glioma, all patients had received radiation, and 57% had received chemotherapy in close proximity to radiation. All images demonstrated contrast enhancement, predominantly in the white matter. Enhancement was present in the periventricular/subependymal region in 50% of cases and the corpus callosum in 27%. The most common pattern of lesion peripheral enhancement was “spreading wavefront” and of interior enhancement was “Swiss cheese/soap bubble.” The enhancing lesion was single in 60% of cases. Mass effect was present in 93% of patients. Location and patterns of enhancement were significantly associated with the interval from brain radiation to the diagnosis of therapy-induced cerebral necrosis, tumor histology, patient age, type of radiation, and administration of systemic chemotherapy. This is the largest study of the morphologic conventional MRI findings in pathologically confirmed therapy-induced cerebral necrosis. We characterized the imaging findings in a variety of tumor types following a variety of radiation treatments and other antineoplastic therapy. These findings may be of value in identifying therapy-induced cerebral necrosis in patients treated for a brain tumor.     

骨肿瘤影像学与病理学相关性研究

目的：探讨骨肿瘤影像学与病理学相关性研究。方法纳入确诊为骨肿瘤的患者50例,回顾性分析纳入患者的影像学及病理学资料,其中50例患者均行数字化 X射线摄影（ DR）检查,其中42例患者行计算机体层摄影术（ CT）检查,40例患者行磁共振成像（ MRI）检查,比较骨肿瘤的影像学特征,比较影像学与病理学诊断结果及良恶性骨肿瘤的诊断正确率。结果 DR和CT在显示骨质增生、破坏、硬化和病灶边界等方面结果相近,但是DR在颅、脊柱、骨盆病灶、细微病灶、软组织阴影不如CT,DR对骨膜反应良好,MRI对骨髓水肿和软组织的特异性最强,但是在显示骨膜增生、硬化、破坏、钙化等方面情况较差。 DR诊断正确率为88．0％,CT诊断正确率为90．5％;MRI诊断正确率为95．0％,3种影像学检查方法对良恶性骨肿瘤的诊断正确率比较无统计学差异（ P＞0．05）。结论 DR平片为骨肿瘤的首选的检查方法,CT主要显示肿瘤的范围和细微结构,MRI对软组织及骨髓水肿具有一定的优势,三者相结合对骨肿瘤的诊治具有优势互补的作用。