Early diagnosis and endovascular interventions for ischemic stroke

In recent years there have been formidable advances in the war against stroke. The understanding and detection of stroke have undergone major progress at a rate previously unseen, partly due to major contributions from neuroradiology. Current routine neuroradiologic evaluation of acute stroke relies mainly on computed tomography scanning, although a number of radiologic modalities are becoming available that are based on various physical and chemical tissue properties, such as magnetic resonance imaging, single photon emission computed tomography, positron emission tomography, and magnetic resonance spectroscopy. All these new techniques allow the study of nervous tissue at the cellular and biochemical levels. A review of current diagnostic techniques for stroke follows in the first part of this article. The current status of endovascular therapy for ischemic stroke is reviewed in the second part of this article.     

Temporal bone imaging

Ameliorated computed tomography techniques and new magnetic resonance sequences have led to an important improvement in temporal bone imaging. Computed tomography is still the method of choice for imaging of temporal bone fractures, middle ear disease, and conductive hearing loss, although magnetic imaging can add important information. Patients with lesions of the cerebellopontine angle; internal auditory canal; inner ear; and, in general, all patients with sensorineural hearing loss, vertigo, and tinnitus are best examined with magnetic resonance imaging. In some cases, however, such as congenital malformations and petrous apex lesions, magnetic resonance imaging and computed tomography are complementary. The value of both modalities is discussed.     

MR imaging of tibial plateau fractures

Magnetic resonance (MR) images of five patients with acute tibial plateau fractures are presented and correlated with both clinical examination and findings at surgical intervention. The role of MR imaging in the evaluation of both osseous and soft tissue deformity in acute trauma, specifically in patients with tibial plateau fractures is discussed. The value of MR imaging as an alternative to computed tomography and arthroscopic evaluation of these patients is emphasized.     

The thoracic roentgen image: emergency and routine indications in the clinic and general practice

Even in the era of rapidly emerging cross-sectional imaging techniques (computed tomography, magnetic resonance imaging) the chest radiograph remains the most frequently performed diagnostic imaging procedure and has not lost any importance to other modalities. After technical considerations the value of chest radiography will be discussed based on the most widely applied indications in emergency and routine clinical settings and the link to subsequent imaging modalities will be outlined.     

Magnetic resonance imaging of the musculoskeletal system: the spine

Magnetic resonance imaging in the patient who has had surgery is discussed. The most common indication for postoperative imaging is in the distinction between postoperative fibrosis and recurrent disc herniation. Magnetic resonance imaging is invaluable in the assessment of potential causes of failed back surgery syndrome such as postoperative infection, arachnoiditis and adjacent segment degeneration. Magnetic resonance imaging assumes a less important role in postoperative patients with metal hardware owing to image degradation secondary to metal artifact. Magnetic resonance imaging has a complementary role with computed tomography evaluation of spinal trauma. It excels at the noninvasive evaluation of spinal deformities and neoplasms.     

The eye

In recent years, the growing application of computed tomography (CT) and magnetic resonance (MR) imaging evaluation of the orbit and globe have dramatically increased the role of imaging and, hence, that of the radiologist in assessing ophthalmologic disorders. This article discusses magnetic resonance imaging features of the most common and less common ocular pathologies, with particular emphasis on the potential of magnetic resonance imaging in the field of ophthalmology.     

Chronic recurrent multifocal osteomyelitis (CRMO). Diaphyseal attack with progressive hyperostosis]

In children, infections involving both the superficial and deep neck spaces are common. Children so affected typically present with fever, neck mass, neck stiffness, and, occasionally, airway compromise. Radiologic modalities used in the evaluation of neck infections include plain lateral neck radiography, ultrasound, computed tomography, and magnetic resonance imaging. All these modalities have proved useful in the treatment of such infections, specifically the decision to perform incision and drainage. The charts of 66 patients-33 with superficial and 33 with deep neck infections-were analyzed with respect to symptoms, signs, computed tomography findings, and need for surgical intervention. Computed tomography was not particularly helpful in superficial neck infections with regard to the decision to perform surgical drainage; however, it did localize and demonstrate the extent of infection. In deep neck infections we found a 92% correlation between computed tomographic evidence of an abscess and surgical confirmation of one. Contrast-enhanced computed tomography remains an excellent tool in the treatment of neck infections in children.     

CT and MRI evaluation of musculoskeletal infection

While the plain film and nuclear medicine bone scan are still the traditional imaging modalities used in the evaluation of musculoskeletal infection, the cross-sectional imaging modalities, computed tomography (CT) and magnetic resonance imaging (MRI), have become critical in the delineation of many types of musculoskeletal infection. In particular, the evaluation of soft tissue infections, including cellulitus, myositis, fasciitis, abscess, and septic arthritis are often best evaluated by MRI or CT due to their excellent anatomic resolution and soft tissue contrast. Even in osseous infection, CT and MRI can give better anatomic delineation of the extent of infection. In cases where the plain film and nuclear medicine bone scan findings are complicated due to previous surgery, trauma, or underlying illness, the anatomic resolution and soft tissue contrast provided by MRI and CT are often necessary to determine if underlying infection exists. MRI's visualization of the bone marrow allows for the sensitive detection of osteomyelitis, although specificity for the diagnosis of osteomyelitis is aided by other findings, including cortical destruction. The CT and MRI findings in the spectrum of musculoskeletal infections are discussed and contrasted, and pitfalls in their evaluation of musculoskeletal infection are described.     

Early diagnosis of rapidly progressive glomerulonephritis

Functional neuroimaging with positron emission tomography previously demonstrated reduced caudate glucose metabolism in virtually all symptomatic patients with Huntington's disease (HD). Single-photon emission computed tomography studies of brain blood flow also have shown caudate abnormalities in patients with HD. The present study compared these two functional imaging modalities in 6 patients with HD who had been symptomatic for fewer than 5 years. All patients had significantly impaired caudate-thalamus and caudate-whole-slice glucose metabolism ratios as measured by positron emission tomography. However, only 3 had clearly abnormal caudate-thalamus activity ratios and 2 had clearly abnormal caudate-whole-slice ratios on single-photon emission computed tomography. These findings indicate that single-photon emission computed tomography imaging of caudate blood flow is a less sensitive indicator of caudate dysfunction in early HD than is positron emission tomography imaging of caudate glucose metabolism.     

Pharmacokinetic considerations in the development of labeled liposomes and micelles for diagnostic imaging

The current status of application of liposomes and micelles as carriers for diagnostic imaging agents in experimental and clinical medicine is considered. Liposomes and micelles loaded with appropriate contrast agents have been shown to be suitable for all imaging modalities, including gamma-, magnetic resonance (MR), and computed tomography (CT). The methods are briefly described to prepare liposomes loaded with various contrast agents, as well as some basic data on their in vitro and in vivo properties and biodistribution. Certain pharmacokinetic considerations associated with the use of plain and long-circulating liposomes and micelles as pharmaceutical carriers are discussed. The application of contrast-loaded liposomes in different modalities for the experimental and clinical imaging of various organs, tissues, and pathological conditions is briefly reviewed. New trends in the preparation and use of contrast-loaded liposomes and micelles are also considered, such as the application of amphiphilic polychelating polymers and polymers for steric protection of microparticulate pharmaceutical carriers.     

Brain sonography, computed tomography, and single-photon emission computed tomography in term neonates with perinatal asphyxia

The clinical diagnosis of hypoxic-ischemic brain injury in neonates can be supported by radiologic studies including cranial sonography, computed tomography (CT), single-photon emission computed tomography (SPECT), magnetic resonance imaging, and positron emission tomography. The role of cranial sonography, CT, and SPECT in term neonates with perinatal asphyxia is reviewed in this article.     

Early cardioverter defibrillator infection: value of indium-111 leukocyte imaging

In the early postoperative period, it may be difficult to diagnose an infected implantable cardioverter-defibrillator system using anatomic imaging modalities such as computed tomography alone. We describe a case that illustrates the complementary physiologic role of indium-111-labeled leukocyte scintigraphy in identifying and defining the extent of early postoperative implantable cardioverter-defibrillator infection.     

CT evaluation of the acute abdomen: bowel pathology spectrum of disease

CT has become the primary imaging modality for the evaluation of the patient with clinical symptoms of an acute abdomen and a confusing clinical picture. Because these patients may have a range of various pathologies, CT has been used successfully to define the presence of disease and localize it to a specific organ or organ system. In this article, we review the various processes that resulted in acute abdomen focusing on the small bowel and colon. Specific entities discussed include appendicitis, diverticulitis, Crohn disease, and ulcerative colitis. Other less common processes, including pseudomembranous colitis, intussusception, and bowel ischemia are also discussed. The specific role of CT scanning and specific CT signs are discussed and addressed. The value of CT in relationship to other modalities and clinical evaluation is discussed and key statistics provided.     

Petrous apex arachnoid cyst: radiographic confusion with primary cholesteatoma

The advent of combined computed tomography (CT) and magnetic resonance imaging (MRI) for the evaluation of petrous apex lesions has improved the otologist's ability to differentiate among many disease processes. Temporal bone CT details osseous anatomy, whereas MRI delineates soft tissue signal characteristics. The employment of these two imaging modalities is often successful in differentiating between cholesterol common entities encountered in the petrous apex. The finding of a smoothly marginated, expansile, bone eroding lesion on CT, coupled with hypointensity on T1-weighted and hyperintensity on T2-weighted images on MRI, is highly suggestive of cholesteatoma. The authors recently encountered two cases of arachnoid cyst involving the petrous apex that shared the same imaging features seen with the more common cholesteatoma. One patient presented with tic douloureux, whereas the other had a spontaneous transotic cerebrospinal fluid leak. The contemporary skull base surgeon should include arachnoid cyst as a rare possibility in the evaluation and treatment of petrous apex lesions.     

A comparative analysis of the existing standards for exposure to ultraviolet radiation

Medical imaging technology is rapidly expanding and the role of each modality is being redefined constantly. PET has been around since the early sixties and gained clinical acceptance in oncology only after an extreme number of scientific publications. Although PET has the unique ability to image biochemical processes in vivo, this ability is not fully used as a clinical imaging tool. In this overview, the role of PET in relation to other tumor imaging modalities will be discussed and the reported results in the literature will be reviewed. In predicting the future of PET, technical improvements of other imaging modalities need to be dealt with. The fundamental physical principles for image formation with computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), photon-emission tomography (PET), and single photon emission CT (SPECT) will not change. The potential variety of radiopharmaceuticals which may be developed is unlimited, however, and this provides nuclear imaging techniques with a significant advantage and adaptive features for future biologic imaging. The current applications of PET in oncology have been in characterizing tumor lesions, differentiating recurrent disease from treatment effects, staging tumors, evaluating the extent of disease, and monitoring therapy. The future developments in medicine may use the unique capabilities of PET not only in diagnostic imaging but also in molecular medicine and genetics. The articles discussed in this review were selected from a literature search covering the last 3 years, and in which comparisons of PET with conventional imaging were addressed specifically. PET studies with the glucose analogue fluorine-18-labeled deoxyglucose (FDG) have shown the ability of detecting tumor foci in a variety of histological neoplasms such as thyroid cancer, breast cancer, lymphoma, lung cancer, head and neck carcinoma, colorectal cancer, ovarian carcinoma, and musculoskeletal tumors. Also, the contribution of the whole body PET (WBPET) imaging technique in diagnosis will be discussed. In the current health care environment, a successful imaging technology must not only change medical management but also demonstrate that those changes improve patient outcome.     

Sinonasal imaging

Recent changes in sinonasal imaging are a direct result of the development of functional endoscopic sinus surgery. Because of this technique, radiologists have noted an increased volume of sinus imaging, developed new imaging techniques, and are interpreting films in a different manner. This article covers the common variants seen on coronal computed tomography, discusses the complications of functional endoscopic sinus surgery, reviews the radiographic criteria for sinusitis, and addresses the role of computed tomography and magnetic resonance imaging in evaluating the sinonasal cavity.     

Reliability and validity of imaging diagnosis of temporomandibular joint disorder

The purpose of this article is to review reliability and validity of imaging diagnosis of temporomandibular joint disorders. Plain-film and tomography are basic imaging techniques for assessment of the temporomandibular joint. These can be used for evaluation of osseous disease and as a baseline for follow-up. In patients with symptoms from the joint, plain-film and tomography are rarely definitive, and evaluation of the soft tissues is frequently necessary. Arthrography, computed tomography, and magnetic resonance imaging have all been used for evaluation of the soft-tissue components of the joints. Accuracy studies of these techniques have demonstrated the highest diagnostic accuracy for magnetic resonance imaging. Arthrography is relatively insensitive for detection of medial and lateral displacements. Magnetic resonance imaging accurately depicts both hard and soft tissues, and this technique is emerging as the prime diagnostic imaging technique in patients presenting with clinical signs and symptoms of a disorder of the temporomandibular joint. The most frequent findings when patients with clinical symptoms of temporomandibular joint disorders are "imaged" are different forms of disc displacement and degenerative joint disease. Studies have demonstrated a high prevalence of different forms of disc displacement in patients, although these abnormalities are also seen in some asymptomatic volunteers. Future research should further refine imaging techniques to come closer to an understanding of the association between morphologic alterations and patient symptoms.     

Relative characteristics of MR angiography and competing vascular imaging modalities

This article reviews the general characteristics of several vascular imaging modalities with the purpose of identifying the distinguishing features of magnetic resonance (MR) angiography. Brief discussions of conventional x-ray film angiography, intravenous and intraarterial digital subtraction angiography (DSA), duplex and color Doppler flow ultrasound (US), computed tomographic (CT) angiography, transesophageal and intravascular US, angioscopy, and MR angiography are presented. The advantages and disadvantages of each are discussed. The general attributes and image quality features of MR angiography, intraarterial DSA, CT angiography, and US are compared. It is concluded that no single imaging modality will presently suffice for all purposes. Because of its noninvasiveness, rapidly improving image quality, and ability to directly provide velocity information, MR angiography is likely to play a role in an increasing number of clinical applications.     

Pulsatile tinnitus associated with a high jugular bulb and slow venous blood flow

A case of permanent pulsatile tinnitus of the left ear in a patient with hypertriglyceridemia is reported. The combined radiological study with computed tomography, magnetic resonance imaging, and digital angiography excluded a glomus tumor and revealed an enlarged, high-position jugular bulb with slow blood flow. Causes of pulsatile tinnitus are discussed. We conclude that imaging techniques play a major role in the diagnosis of head and neck vascular abnormalities.     

The radiographic evaluation of sinonasal tumors: an overview

It is axiomatic that advances in head and neck imaging improve our understanding of head and neck diseases. Dramatic improvements in radiologic imaging in recent years have, as a corollary, dramatically improved our understanding of sinonasal tumors. Older techniques such as plain film radiography and multidirectional tomography poorly delineate normal anatomy and pathologic changes in the craniofacial region. Modern imaging modalities depict sinonasal tumors and their metastases in detail, yielding information that allows treatment planning to proceed rationally. The radiologic examination is commonly employed as a precise "map" for implementation of therapy, and imaging studies are essential in the follow-up evaluation for tumor residual or recurrence. This article provides an overview of the current contributions made by head and neck radiology to the understanding and clinical management of sinonasal tumors.