Computed tomography and magnetic resonance imaging findings of acquired dacryocystoceles

In this study, radiological findings of acquired dacryocystocele are presented. A total of 13 dacryocystoceles including bilateral in two of the patients, in four patients on the left and in five patients on the right, were determined. Six of the patients had dacryocystocele infection. Average density of the non-infected dacryocystoceles was 11.8±7.8 Haunsfield units (HU), while the median density value of infected ones was 35.0 HU. There was expansion on unilateral nasolacrimal duct in four patients. Acquired dacryocystoceles are rare masses in medial canthal area, and their radiological imaging findings may vary based on etiological factors and presence of infections.     

Computed tomography and magnetic resonance imaging of congenital abnormalities of the temporal bone

Congenital abnormalities of the temporal bone are mostly accompanied by conductive or sensori-neural hearing loss. Before any therapeutic procedures are done high resolution CT (HRCT) and magnetic resonance imaging (MRI) should be performed to establish the correct diagnosis and to plan the potentially surgical intervention. HRCT best depicts osseous changes especially those of the external auditory canal and the middle ear containing the ossicles and the osseous structures of the temporal bone and the petrous bone containing the inner ear. MRI excellently shows soft tissue changes of the inner ear especially on the high resolution 3DT2-weighted sequences which give a superb contrast between the nerves and the cerebro-spinal fluid. Malformations of the external auditory canal consists of aplasia or hypoplasia and those of the middle ear range form extreme hypoplasia or aplasia to very mild deformations of the ossicles. Malformations of the inner ear also range form complete aplasia to very mild hypoplasia of the organs of the inner ear as well as malformations concerning the nerves in the internal auditory canal range from aplasia to hypoplasia. Malformations of the temporal bone can either occur isolated or in combination in which malformations of the external and middle ear may be accompanied by those of the inner ear. Furthermore, malformations of the temporal bone may also occur in otofacial, otocervical or otoskeletal syndromes. These syndromes may be accompanied by certain malformations of the temporal bone. HRCT and MRI are both excellent methods to depict congenital abnormalities of the temporal bone and of the inner ear and should be used as complementary methods because HRCT best depicts osseous changes and MRI superbly depicts soft tissue changes. Both methods are important to establish the correct diagnosis to plan the therapeutic procedures.     

Magnetic resonance imaging of the cerebello-pontine angle

A variety of extra-axial lesions occurring at the cerebello-pontine angle was examined by magnetic resonance imaging (MRI). Differences in spin sequence characteristics were found between neurilemmomas and meningiomas, with neurilemmomas exhibiting a greater increase in T2 than meningiomas. The T1 images were of less value in differentiating between neurilemmomas and meningiomas but were of value in the diagnosis of vascular lesions, due to the decreased T1 of blood clot. The T1 images were also of value in the assessment of tumour size and in the diagnosis of an epidermoid cyst. Extension of tumour into the internal auditory meatus was seen on MRI with acoustic neuromas and with one other lesion. The transverse perspective was of greatest value in lesion assessment. The coronal perspective was useful in certain situations but the sagittal perspective was of minimal clinical value.     

Computed tomography and magnetic resonance imaging of the pericardium

Computed tomography is an established modality for the evaluation of the pericardium. It is used to evaluate complicated pericardial effusions, pericardial thickening, calcific pericarditis, pericardial cysts, postoperative changes and primary and metastatic neoplasms of the pericardium. Magnetic resonance imaging is being used with increasing frequency in the evaluation of pericardial disease. It offers advantages over computed tomography, including a potential for tissue characterization, absence of ionizing radiation or need for intravenous contrast medium, and the ability to scan in any plane. Disadvantages include greater cost, longer examination times and the inability to identify calcification positively.     

Computed tomography and magnetic resonance imaging of mediastinal tumors

We describe the clinical, pathological, and imaging findings of mediastinal tumors with focus on thymic hyperplasia, thymic epithelial tumors, and germ cell tumors, malignant lymphoma, and various cystic masses. Chemical shift magnetic resonance imaging (MRI) is useful in characterization of the normal thymus and differentiation of hyperplastic thymus and thymic tumors. In contrast to noninvasive thymomas, invasive thymomas and thymic carcinomas show a more aggressive growth pattern. Local invasion and pleural spread are characteristic of invasive thymoma and mediastinal lymphadenopathy and distant metastasis suggest thymic carcinomas. Mature teratoma typically shows various computed tomography (CT) attenuation, and MR signal intensity depending on its contents and fat tissue and bone within the lesions are its characteristic findings. Seminomas typically have homogenous internal CT attenuation and MR signal intensity with minimal contrast enhancement. Nonseminomatous malignant germ cell tumors characteristically show prominent internal degenerative changes and invasion to the adjacent structures. In mediastinal lymphomas, a residual mass is common after treatment and MRI provides important information in distinguishing viable tumors from residual benign masses. Some mediastinal cysts may reveal high attenuation similar to solid lesions on CT depending on their contents and MRI can be useful in the differentiation of cystic masses from solid lesions.     

Computed tomography and magnetic resonance imaging of the orbital apex

This article describes the CT and MR appearance of the orbital apex and masses in this region. The sectional anatomy by axial, coronal, and sagittal planes as well as the thin-layer technique used to accomplish this is detailed first. Then the application of these techniques to the presence of tumors is illustrated and discussed.     

Computed tomography and magnetic resonance imaging diagnosis of thymic cyst

A case of mediastinal thymic cyst evaluated by computed tomography and magnetic resonance imaging is presented. The anterior mediastinal mass was well-demarcated and measured 10 Hounsfield units on the computed tomographic scan. The lesion showed intermediate signal intensity on T1-weighting and became hyperintense on T2-weighted images. These computed tomography and magnetic resonance imaging features suggested a cystic structure, which proved to be a benign thymic cyst on pathologic examination.     

Computed tomography and magnetic resonance imaging evaluation of patellofemoral instability

Malalignment and tracking abnormalities of the patellofemoral joint are common causes of anterior knee pain,which are often difficult to evaluate clinically. Conventional radiography, as well as the cross-sectional imaging modalities of computed tomography (CT) and magnetic resonance imaging (MRI) are useful tools for both detecting and quantifying these abnormalities. Acute transient dislocation of the patella, on the other hand, is a relatively uncommon injury accounting for only 2% to 3% of all acute injuries of the knee, and can also be a difficult diagnosis to establish on the basis of history and physical findings alone. MRI is a sensitive, noninvasive method for detecting prior acute transient dislocation of the patella. This article begins by describing the role of CT and MRI as it pertains to the detection of abnormal patellofemoral tracking. Both static and dynamic techniques are described along with the standard criteria used to establish and quantify patellofemoral malalignment abnormalities. Next, the constellation of MRI findings most commonly encountered after acute transient dislocation of the patella are described. These findings include a typical bone bruise pattern involving the anterolateral aspect of the lateral femoral condyle and inferomedial patella, hemarthrosis, and injury to the medial soft-tissue restraints (especially the medial patellofemoral ligament). After transient dislocation of the patella, patients with significant osteochondral injury or disruption of the medial soft-tissue restraints may benefit from surgical repair. The role of MRI in preoperative planning is discussed as it relates to the detection of osteochondral injuries as well as injury to the medial soft-tissue restraints.     

眼色素膜黑色素瘤的CT与MRI研究

目的研究色素膜黑色素瘤的ＣＴ和ＭＲＩ表现，探讨最佳ＭＲＩ的扫描序列。材料与方法１５例患者用各种ＭＲＩ序列进行扫描，其中１１例行ＣＴ扫描，并与手术病理进行对照。结果ＣＴ示９例表现为与眼外肌等密度的肿块，２例肿瘤太小未能显示。ＭＲＩ示１４例具有典型的短Ｔ１、短Ｔ２信号，１例３ｍｍ高度的虹膜黑色素瘤在Ｔ１ＷＩ上未能显示；１１例伴有视网膜脱离，呈短Ｔ１及长Ｔ２信号，与肿瘤在Ｔ１ＷＩ上很难区分。使用脂肪抑制和增强扫描的Ｔ１ＷＩ能较好地显示较小肿瘤（高度＜５ｍｍ）能区分肿瘤及其伴发的视网膜脱离。结论ＭＲＩ显示黑色素瘤的准确率和特异性较ＣＴ和Ｂ超优越。     

Computed tomography and magnetic resonance imaging findings of soft tissue perineurioma

Soft tissue perineurioma is an uncommon benign peripheral nerve sheath tumor, although it is the most common subtype of perineuriomas. We present a case of soft tissue perineurioma in the left groin of a 48-year-old man. Precontrast computed tomography showed a homogeneous hypodense mass that showed faint enhancement. The mass appeared with hypointensity on T1-weighted magnetic resonance (MR) images and heterogeneous hyperintensity on T2-weighted MR images. Slight contrast uptake was noted on enhanced T1-weighted MR images with fat suppression. Although these CT and MR imaging findings were nonspecific, the overall imaging features are similar to those of schwannomas.     

Computed tomography and magnetic resonance imaging of dilated lumbar lymphatic trunks

We report a patient in whom computed tomography (CT) scanning demonstrated bilateral para-aortic lesions, originally misinterpreted as lymphadenopathy, but shown by a combination of CT, lymphangiography and magnetic resonance imaging to represent dilated lumbar lymphatic trunks. This case illustrates a further para-aortic lesion which may be mistaken for lymphadenopathy on cross-sectional imaging.     

Computed tomography and magnetic resonance imaging of lesions at masticator space

We aim to review the normal anatomy and imaging appearance of masticator space lesions. Because the masticator space is not amenable to direct examination, cross-sectional imaging with computed tomography and magnetic resonance imaging play an important role in diagnosis and characterization of lesions occurring there. Masticator space lesions can be classified on the basis of their origin into the following categories: inflammatory lesions, benign tumors, malignant tumors, vascular lesions, and developmental lesions. A diverse spectrum of malignant tumors and benign lesions are seen extending from the adjacent spaces. In addition, one should also be familiar with pseudolesions as well as post-treatment changes in the masticator space that can be mistaken for pathologic conditions.     

Computed tomography and magnetic resonance imaging in cystic fibrosis lung disease

Computed tomography (CT) is the current "gold standard" for assessment of lung morphology and is so far the most reliable imaging modality for monitoring cystic fibrosis (CF) lung disease. CT has a much higher radiation exposure than chest x-ray. The cumulative radiation dose for life-long repeated CT scans has limited its use for CF patients as their life expectancy increases. Clearly, no dose would be preferable over low dose when the same or more relevant information can be obtained. Magnetic resonance imaging (MRI) is comparable to CT with regard to the detection of most morphological changes in the CF lung. It is thought to be less sensitive to detect small airway disease. At the same time, MRI is superior to CT when it comes to the assessment of functional changes such as altered pulmonary perfusion. The recommendation is to further reduce radiation dose related to the use of CT and to use MRI in the follow-up of morphological changes where possible.     

Computed tomography and magnetic resonance cholangiography

In patients with biliary obstruction, determining the level and the cause of the obstruction is essential because it can be a key factor for the next step in diagnostic or therapeutic intervention. Noninvasive cholangiography, such as computed tomography (CT) cholangiography or magnetic resonance (MR) cholangiography, allows the diagnosis of cause and level of biliary disease with minimal risk. Traditional magnetic resonance cholangiopancreatography (MRCP) is an established and effective noninvasive diagnostic modality particularly for extrahepatic biliary tract evaluation. Intrahepatic biliary duct evaluation and functional MR, including evaluating for leaks and gallbladder dyskinesia and outlet obstruction, are evolving diagnostic techniques that show promising results. CT cholangiography techniques are especially useful when MRI is not available or contraindicated or when the quality of MRCP images is suboptimal. CT cholangiography is particularly useful as an adjunct to surgery or postsurgical cases. The primary limitation of cholangiographic contrast-enhanced CT cholangiography (the most prevalent type of CT cholangiography) is its hindrance by poor liver function and/or high-grade biliary obstruction. In this setting MRCP is clearly superior. There are different types of CT cholangiography and MRCP. This article discusses the types of CT cholangiography and MRCP techniques and their clinical applications.     

Computed tomography and magnetic resonance imaging findings in cerebral hydatid disease

Purpose: The purpose of this study was to describe the discriminative computed tomography (CT) and magnetic resonance imaging (MRI) features of cerebral hydatid disease.Methods: The CT and MRI findings of four cases of surgically proven cerebral hydatid cysts were retrospectively reviewed. Results: CT demonstrated well-defined cystic lesions with no perilesional oedema and no contrast enhancement in all cases except one recurrent disease that showed both peripheral oedema and rim enhancement. MR images revealed well-defined cystic lesions with a quite clear rim that showed relative hypointensity limited to some aspects of the cyst walls on T2-weighted images. The cysts were spherical and obvious mass effect was observed on both CT and MR examinations. Conclusions: Although the cystic nature of intracranial hydatid disease could be equally well demonstrated on CT and MR examinations, CT is superior in detecting calcification of the cyst wall or septa, when present, and MR is better in demonstrating cyst capsule, detecting multiplicity and defining the anatomic relationship of the lesion with the adjacent structures and helps in surgical planning.     

Computed tomography and magnetic resonance imaging in diseases of the thyroid and parathyroid

Disease of the parathyroid glands presents most often with hypercalcaemia secondary to excess parathormone (PTH) production. This is due to a solitary functioning parathyroid adenoma. The role of imaging is primarily to localise the functioning adenoma. Disease of the thyroid may present with a neck mass or thyroid dysfunction. This paper focuses on the approach and choice of imaging techniques in the evaluation of hypercalcaemia and thyroid masses.     

Computed tomography and magnetic resonance imaging of the female lower urinary tract.

Computed tomography (CT) and magnetic resonance (MR) imaging have become invaluable imaging modalities in the diagnosis of diseases involving the lower urinary tract. Both CT and MR imaging are able to accurately stage bladder carcinoma, with MR imaging able to distinguish between superficial and deep muscle invasion of tumor. CT and MR are also the studies of choice for evaluating retroperitoneal fibrosis, which often affects the urinary tract; MR imaging is often able to detect the presence of active inflammation and occasionally rule out a malignant cause. MR imaging holds promise for the evaluation of stress urinary incontinence and urethral disease. Although diseases of the distal ureter continue to be most accurately diagnosed by intravenous urography and retrograde studies, CT and MR imaging may serve a helpful secondary role.     

Computed tomography and magnetic resonance imaging of unusual causes of ankle pain

Computed tomography and MRI are frequently utilized to evaluate ankle pain that remains unexplained by radiography. The most common causes of ankle pain are related to trauma and the imaging appearances of these entities are well established in the radiologic and orthopedic literature. A smaller percentage is comprised of non-traumatic disorders. Our goal is to emphasize the value of CT and MRI in recognition of these less common and unusual causes of ankle pain.