Magnetic resonance imaging phase encoding: a pictorial essay

A set of MRI images with various degrees of phase encoding were generated from the same raw data set. The resultant pictorial teaching aid is useful in developing an intuitive understanding of the mechanics and principles of phase encoding in two dimensional, Fourier transform magnetic resonance imaging.     

MR imaging of anterior knee pain: a pictorial essay

Anterior knee pathology is a frequent cause of joint pain and limitation of function and mobility among patients presenting to an orthopaedic department. Proper recognition and treatment of pathologic conditions depend on the knowledge of normal anatomy and of the various abnormalities, which affect this area of the knee and may present with anterior knee pain. A broad array of benign and malignant processes may be manifested as anterior knee discomfort, and this common clinical entity is among the most frequent indications for MR imaging of the lower extremities. Clinical history and physical examination are also of paramount importance. The disorders can be categorized and differentiated primarily according to their location. Traumatic or non-traumatic disorders of the patella, patellar retinacula, quadriceps and patellar tendons and supra or infrapatellar fat pad can be the source of symptoms. This article includes a comprehensive pictorial essay of the characteristic MR features of common and uncommon disorders causing anterior knee pain. For accurate assessment of the aforementioned clinical problem, a radiologist should be able to identify typical MR imaging patterns that contribute in establishing the correct diagnosis and thus tailoring the appropriate therapy. Level of evidence IV.     

Characteristic imaging features of body packers: a pictorial essay

The drug-trafficking business has risen tremendously because of the current increased demand for illegal narcotics. The smugglers conceal the drugs in their bodies (body packers) in order to bypass the tight security at international borders. A suspected body packer will normally be sent to the hospital for imaging investigations to confirm the presence of drugs in the body. Radiologists, therefore, need to be familiar with and able to identify drug packets within the human body because they shoulder the legal responsibilities. This pictorial essay describes the characteristic imaging features of drug packets within the gastrointestinal tract.     

MR imaging of non-CNS fetal abnormalities: a pictorial essay.

The recent popularity of prenatal magnetic resonance (MR) imaging has been associated with the development of ultrafast MR imaging techniques such as the single-shot fast spin-echo sequence. However, the majority of previous reports have concerned the fetal central nervous system (CNS) and chest disorders. MR imaging can demonstrate non-CNS fetal anatomy and pathologic conditions clearly. With its excellent tissue contrast, MR imaging provides information that supplements that provided by ultrasonography (US), especially in cases of neck, chest, and gastrointestinal lesions. Because of its large field of view, MR imaging allows evaluation of the relationship between a large lesion and adjacent structures. MR imaging should be considered if the diagnosis of a suspected non-CNS lesion is unclear at fetal US. MR imaging plays an important complementary role to US in cases of non-CNS fetal lesions and will be further accepted for fetal imaging in the future.     

Magnetic resonance imaging of the fetal lung: a pictorial essay

Ultrasound, which is now a widely available and generally accepted, low-cost technique with real-time properties, is the screening investigation of choice in fetal medicine. However, enthusiasm for fetal prenatal magnetic resonance imaging (MRI) is rising, because of the absence of known biological risks, the increasing ease of performing of fetal MRI and the superb contrast resolution provided. Over the last 10 years, the technology has advanced dramatically. Fast imaging sequences have allowed better MRI visualization of the unborn patient than ever before. As a consequence, experience with fetal MRI is gradually expanding. We are beginning to appreciate the clinical conditions where fetal MRI can complement the ultrasound findings. Apart from the central nervous system, MRI of the fetal lung has received the most attention. Fetal MRI can be used to assess thoracic structural anomalies, lung development as well as maturation. The introduction of fetal therapy for severe lung hypoplasia, associated with congenital diaphragmatic hernia (CDH), has recently boosted the application. This review aims to highlight MRI techniques used to image the lungs of the unborn child and to point out their strengths and limitations in specific conditions.     

MR imaging of the postoperative knee: a pictorial essay.

Magnetic resonance (MR) imaging of the postoperative knee has become more common because more arthroscopic repair procedures are being performed. The most common procedures include partial meniscectomy and meniscal repair, anterior cruciate ligament (ACL) reconstruction, and cartilage repair procedures. Specific findings of a retorn meniscus following meniscal repair or partial meniscectomy are increased signal intensity extending through the site of repair on T2-weighted images, displaced meniscal fragments, and abnormal signal intensity at a site distant from the repair. Findings of ACL graft disruption on T2-weighted MR images include absence of intact graft fibers and increased signal intensity similar to that of fluid within the expected region of the graft. Partial tears of the graft appear as areas of increased signal intensity affecting a portion of the graft with some intact fibers still present. An impinged ACL graft may appear to be draped over the anterior inferior edge of the intercondylar roof or be posteriorly bowed. Localized anterior arthrofibrosis appears on T1-weighted MR images as a focal nodular lesion of low signal intensity that is anterior to the ACL graft in the intercondylar notch and is indistinguishable from adjacent joint fluid. On T2-weighted images, the nodule is well differentiated from high-signal-intensity joint fluid. Finally, MR imaging has been shown to be accurate in the evaluation of cartilage repair tissue. Knowledge of the normal MR imaging appearance of the knee after the more common repair procedures will allow radiologists to recognize complications associated with such procedures.     

Magnetic resonance imaging of spinal cord trauma: a pictorial essay

Assessing a patient with clinical signs of acute spinal cord trauma is an emergency. A radiological work-up is crucial in determining management, and magnetic resonance imaging (MRI) is the modality of choice. It should therefore be performed immediately, preferably within 3 hours, even when plain radiography does not show an abnormality. By choosing an appropriate imaging protocol, it is possible to assess the spinal cord, joints, muscles, ligaments and bone marrow of the spine. Moreover, early MRI findings assist in determining functional prognosis. A major limitation to early MRI is that the examination is usually restricted to stable trauma patients because of the difficulties in monitoring ventilated patients during scanning. However, when an anaesthesiologist with experience in MRI and MR-compatible monitoring equipment is available, even these patients can be safely examined. MRI is also indicated for the evaluation of patients with late complications and sequelae following spinal cord trauma, since many of these chronic lesions are potentially treatable.     

Multimodality imaging of hepato-biliary disorders in pregnancy: a pictorial essay

Hepato-biliary disorders are rare complications of pregnancy, but they may be severe, with high fetal and maternal morbidity and mortality. Imaging is, therefore, essential in the rapid diagnosis of some of these conditions so that appropriate, life-saving treatment can be administered. This pictorial essay illustrates the multimodality imaging features of pregnancy-induced hepato-biliary disorders, such as acute fatty liver of pregnancy, preeclamsia and eclampsia, and HELLP syndrome, as well as those conditions which occur in pregnancy but are not unique to it, such as viral hepatitis, Budd–Chiari syndrome, focal hepatic lesions, biliary sludge, cholecystolithiasis, and choledocholithiasis.     

CT enteroclysis: a pictorial essay

The objective of the CT-enteroclysis is to distend the entire small intestine equally and sufficiently using a nasojejunal probe and an enteroclysis catheter for administration of a neutral opacifying agent. Today this is the best radiological method available to explore the small intestine because of its good spatial resolution and the rapidity of the exam. It is a high-performance exam when searching for transmural and extramural pathologies, in particular small tumoral lesions. It remains less effective in the exploration of anomalies of the lumen's mucosal lining, contrary to videocapsule endoscopy and the double-balloon enteroscope. It has been recognized that the CT-enteroclysis is a high-performance examination that should replace the small-bowel follow-through exam. However, there are undeniable disadvantages: higher does of radiation, patient discomfort during placement of the enteroclysis catheter, false-positive results, long interpretation time, and the impossibility of exploring the endoluminal aspect of the intestinal mucosal lining. All radiologists should therefore become familiar with the problems involved with this exam and its signs and patterns, which are illustrated in this pictorial review.     

Diffusion-weighted MR imaging of posterior reversible leukoencephalopathy syndrome: a pictorial essay

Posterior reversible leukoencephalopathy syndrome is characterized by reversible white matter lesions. However, ischemic injury with irreversible damage may occur. This pictorial essay illustrates MR features associated with posterior reversible leukoencephalopathy syndrome. We will emphasize the role of diffusion-weighted imaging for the discrimination of irreversible ischemic injury from reversible vasogenic edema.     

Genitourinary trauma: a pictorial essay

Genitourinary trauma is often overlooked in the setting of acute trauma. Usually other more life-threatening injuries take precedence for immediate management. When the patient is stabilized, radiologic imaging often plays a key role in diagnosing insults to the upper and lower genitourinary tract in the setting of trauma. Our aim is to provide a pictorial assay of imaging findings in upper and lower tract genitourinary trauma from a variety of mechanisms including blunt trauma, penetrating trauma, and iatrogenic trauma. A patient archiving and communication system will be used to review imaging studies of patients at our institution with genitourinary tract trauma. Cases of renal, ureteral, bladder, urethral, penile, and scrotal trauma will be considered for inclusion in our study. Multimodality imaging techniques will be reviewed. The imaging and pertinent findings that occur in various types of genitourinary trauma are outlined. Genitourinary trauma is often missed in the frenzy of acute trauma. It is important to have a high suspicion for injury especially in severe trauma, and in particular clinical settings. Although often not life threatening, recognizing the diagnostic imaging findings quickly is the realm of the astute radiologist so appropriate urologic management can be made.     

Fetal magnetic resonance imaging of the central nervous system: a pictorial essay

Prenatal ultrasonography is the primary screening modality for the evaluation of fetal pathology. Ultrafast fetal MRI is a recent development that examines the fetus in utero. The short acquisition times (as short as 400 ms/slice) allow to picture freeze the fetus without the need for fetal sedation. The high spatial resolution, good contrast-to-noise ratio, and the multiplanar capabilities are especially advantageous in pathologies of the fetal central nervous system (CNS). Fetal MRI currently serves as a second-line imaging tool for complex fetal cerebral malformations and pathologies. Fetal ventriculomegaly, lesions within the posterior fossa, and abnormalities in cerebral myelination, migration, and sulcation are particularly well identified.     

Fly through ultrasound imaging in assessment of carotid atherosclerosis: a pictorial essay

To assess fly through ultrasound imaging (FTUS) in evaluation of carotid artery atherosclerosis, we prospectively performed conventional sonography and FTUS of the carotid artery on 66 patients with suspicion for atherosclerosis. Characteristics of arterial intima, atherosclerotic plaque, luminal narrowing, and carotid stent graft displayed on FTUS were compared with that on conventional sonography. On FTUS, normal carotid artery wall was smooth in appearance, mild carotid atherosclerosis appeared focal arterial wall irregularity and small plaque formation, arterial luminal reduction resulted from progressive artery plaques, and carotid stent had irregular inner lumen and tight fit against the arterial wall. A total of 38 plaques were detected by conventional sonography, while 48 plaques were depicted by FTUS in 25 patients. Using magnetic resonance angiography as a reference standard, 17 cases with >50% and 3 cases with < 50% luminal reduction measured on FTUS. However, all those 20 cases were measured with >50% luminal reduction on conventional sonography. Compared with conventional sonography, FTUS can dynamically display intraluminal structure on real-time three-dimensional imaging morphologically to improve the accuracy in detecting atherosclerotic plaque and assessing luminal narrowing in the carotid artery.     

MR imaging of late radiation therapy- and chemotherapy-induced injury: a pictorial essay

Radiation to the brain and adjuvant chemotherapy may produce late delayed changes from several months to years after treatment of intracranial malignancies with a reported prevalence of 5–24%. The pattern of treatment-related injury may vary from diffuse periventricular white matter lesions to focal or multifocal lesions. Differentiation of treatment-related injury from tumor progression/recurrence may be difficult with conventional MR imaging (MRI). With both disease processes, the characteristic but nonspecific imaging features are vasogenic edema, contrast enhancement, and mass effect. This pictorial essay presents MRI spectra of late therapy-induced injuries in the brain with a particular emphasis on radiation necrosis, the most common and severe form. Novel MRI techniques, such as diffusion-weighted imaging (DWI), proton MR spectroscopy (MRS), and perfusion MRI, improve the possibilities of better characterization of treatment-related changes. Advanced MRI techniques allow for the assessment of metabolism and physiology and may increase specificity for therapy-induced changes.     

Imaging bicipitoradial bursitis: a pictorial essay

Skeletal Radiology - Although bicipitoradial bursitis is not commonly seen, when it does occur, it can frequently lead to diagnostic difficulty, mimicking either a soft-tissue tumor or infection....     

Diffusion-weighted echo-planar MR imaging: clinical applications and pitfalls -- a pictorial essay

Diffusion-weighted imaging (DWI) provides unique information about various pathological changes of the brain. DWI is sensitive for the detection of hyperacute infarcts, and useful in distinguishing acute or subacute infarcts from chronic infarcts. DWI is useful in differentiating cytotoxic edema from vasogenic or interstitial edema, which may help to determine prognosis. DWI is useful in differentiating cystic or necrotic tumors from abscesses or epidermoids. DWI can discriminate nonenhanced tumor infiltration from vasogenic edema, and differentiate dysmyelination from demyelination.     

Computed tomography and angiographic interventional features of ruptured hepatocellular carcinoma: pictorial essay.

Spontaneous rupture is an uncommon and potentially fatal complication of hepatocellular carcinoma (HCC), occurring in approximately 15% of patients with HCC in Asia and 3% in the United Kingdom.3 The prognosis for hemorrhage of HCC is poor, particularly in those patients with underlying cirrhosis and severe coagulopathy. Computed tomography (CT) rather than angiography is the first-line modality for the detection of rupture. CT can confirm the diagnosis of ruptured HCC and can also help in assessing other organs if the diagnosis is not clear prior to imaging. It allows for an assessment of the entire liver, including the portal vein, which aids in determining the feasibility of embolization and resection. Since the rate of bleeding must normally exceed 1 mL/min before it can be detected on angiography and the extravasation of contrast is present in less than 20% of cases, CT is a more helpful modality. The optimal CT protocol for this condition is triphasic: the precontrast phase allows for assessment of ethiodized oil (lipiodol) uptake, the arterial phase demonstrates enhancement of the mass, and the portal venous phase allows for assessment of the portal veins. Various treatment options have been proposed: transarterial catheter embolization (TACE), emergency liver resection, and delayed resection. Surgical treatment is difficult, if not impossible. In most cases, rupture is a result of diffuse intrahepatic spread of the tumour and underlying liver cirrhosis. Many authors have concluded that a multidisciplinary management that includes TACE as the primary procedure followed by a delayed resection is the preferred treatment. This pictorial essay reviews the radiologic features of spontaneously ruptured HCC on CT imaging and of treatment by angiography.