The contribution of routine gray-scale sonography in the gastrointestinal tract has been augmented by the addition of duplex Doppler and, more recently, color Doppler imaging. Many recent reports focus on the deep abdominal applications of these modalities. Although duplex tracing remains the basis of most diagnoses, the use of color Doppler imaging has facilitated the performance of these examinations. Endosonography performed with high-resolution transducers in the lumen of the gut is another exciting and expanding area. Staging of gastrointestinal tumors is the major application of this modality. Future sonographic developments include the promise of contrast agents.
In the past year, Doppler echocardiography has continued to transform the "echo laboratory" into a "cardiac imaging and hemodynamics laboratory." Evaluation of blood flow through the cardiac chambers and great vessels is moving from semiquantitative to quantitative. The potential for measuring mitral regurgitant flow more precisely has been demonstrated by evaluating the zone of flow acceleration that occurs on the left ventricular side of the mitral valve. Direct imaging of pulmonary venous return to the left atrium using transesophageal Doppler echocardiography has also allowed more precise quantification of mitral regurgitation. Left ventricular systolic function may be better quantified in patients with mitral regurgitation by calculating the ratio of the change in pressure to the change in time from the continuous wave spectrum of regurgitant flow. The practical application of transmitral flow.in evaluating diastolic function has been applied to cardiac amyloidosis.
High-resolution CT remains the imaging modality of choice for investigation of the temporal bone, especially if there is suspicion of bony involvement. The advances in two- and three-dimensional reconstruction are helpful for visualizing complex osseous structures. Nevertheless, the most exciting advances regarding imaging of the temporal bone were achieved in MR imaging. Improvement of surface-coil technology, application of gadopentetate dimeglumine, and development of new imaging sequences led to an increasing importance for MR imaging, especially in inflammatory diseases. Soft tissue structures in neoplastic diseases in the temporal bone are better depicted on MR imaging. Therefore, in some cases, both modalities are used to detect soft tissue and bony abnormalities of the temporal bone, especially for cases using surgical management.
The highlight of recent articles published on pediatric chest imaging is the potential advantage of digital imaging of the infant's chest. Digital chest imaging allows accurate determination of functional residual capacity as well as manipulation of the image to highlight specific anatomic features. Reusable photostimulable phosphor imaging systems provide wide imaging latitude and lower patient dose. In addition, digital radiology permits multiple remote-site viewing on monitor displays. Several excellent reviews of the imaging features of various thoracic abnormalities and the application of newer imaging modalities, such as ultrafast CT and MR imaging to the pediatric chest, are additional highlights.
CT and MRI have greatly facilitated evaluation of pathology of the three pairs of major salivary glands and the hundreds of minor salivary glands. Imaging can frequently offer a specific histological diagnosis for benign and malignant neoplasms of the parotid, submandibular, and sublingual glands. Obstruction, infection, autoimmune processes, and congenital anomalies also are readily diagnosed. CT and MRI studies assess the anatomic extent of minor salivary gland neoplasms. Sialography continues to provide useful information about intrinsic abnormalities of the parotid and submandibular ducts.
Increasing interest in metabolic diseases of the brain has revealed more specific patterns of disease, permitting us to make more accurate diagnoses or to suggest a more limited differential list of considerations. MR imaging is also useful in monitoring the course of the disease in processes for which treatment is available.
The year 1991 was a year of innovation, with interesting papers published in the imaging as well as the medical and surgical literature. Several reports described novel techniques using transcutaneous ultrasound to evaluate the swallowing mechanism; another used CT and ultrasound of the neck for staging esophageal carcinoma. The new field of endoscopic ultrasound was again a subject of much investigation and was compared with CT in the staging of esophageal cancer. One study suggested that endoscopic ultrasound was superior to CT in staging esophageal cancer whereas another found that endoscopic ultrasound had an accuracy rate of only 59% in detecting local invasion. MR imaging and CT were reevaluated for staging esophageal carcinoma using criteria that were modified slightly from previous techniques. These new criteria simplified the detection of aortic and pericardial invasion and staged esophageal carcinoma accurately. The definition of "normal" was refined this year. For instance, in a study of swallowing in asymptomatic and presumably normal elderly individuals, a number of findings were encountered that are considered abnormal in the younger patient. Another study documents normal swallowing patterns in the infant. Other papers provided refinements in radiographic examination techniques as well as excellent reviews of anomalies, esophagitis, and the management of esophageal foreign bodies. The review is divided into two sections that discuss the pharynx and the esophagus.
New developments in imaging of the liver have continued during the past year. Ultrasonography, particularly color Doppler applications, and invasive CT techniques are used with increasing frequency. New contrast agents are being tested for improved ultrasonographic detection of liver lesions, and faster imaging sequences and variations on older techniques are innovations in the field of MR imaging. Correlation studies addressed the issue of which are the best-suited imaging methods for the various pathologic changes in the liver.
Selected papers published over the past year in the areas of radionuclide hepatobiliary imaging, gastric emptying, and gastrointestinal bleeding are reviewed. Two advances in cholescintigraphy are particularly emphasized and discussed. First, morphine-augmented cholescintigraphy has established itself as an accurate alternative to 2 to 4 hour delayed imaging for the diagnosis of acute cholecystitis. Second, sincalide-stimulated cholescintigraphy with calculation of a gallbladder ejection fraction has proven to be a useful test for confirming the clinical diagnosis of chronic acalculous cholecystitis. Other hepatobiliary papers reviewed include those on the utility of cholescintigraphy in gallbladder perforation, hepatocellular carcinoma, liver transplantation, enterogastric reflux, and for the diagnosis of the postoperative complications of laparoscopic cholecystectomy and gallstone lithotripsy. The second major area of review includes papers published over the past year on gastric emptying, including investigations of methodology, physiology and pathophysiology, and clinical utility. A few papers utilizing radionuclide techniques for localizing gastrointestinal bleeding will also be reviewed.
This paper reviews the development of contrast media used in diagnostic imaging. It discusses important scientific and societal issues relating to the newer nonionic agents and reviews recent clinical and investigational reports on contrast agents for the various imaging modalities.
Magnetic resonance imaging has played a role in the diagnosis of thoracic disease; however, the role has been limited compared with that of CT. In the past year, there were a few additional reports of MR imaging in the diagnosis of thoracic disease, which include a multi-institutional study comparing MR imaging with CT and histopathologic correlative studies evaluating gadopentetate dimeglumine-enhanced MR imaging. Furthermore, several excellent reviews of MR imaging of thoracic disease were published. In general, the recent literature supports information previously reported. In the future, developments in lung parenchymal imaging and pulmonary vascular imaging are anticipated.
A review of Paget's disease produces few surprises; however, several good articles have recently been published on its appearance, on MR imaging, sarcomatous degeneration, and the disease-related occurrence of multicentric giant-cell tumors. One recent paper illustrated the possible progression of fibrous dysplasia occurring in the skull after adolescence, a finding that does not occur elsewhere. An excellent review article on the normal and abnormal calcaneus is reviewed, and two brief reports on skeletal angiomatosis are discussed. Condensing osteitis of the clavicle is well described in one article that proves it to be an entity distinct from chronic recurrent multifocal osteomyelitis of the clavicle seen in children. Finally, a number of articles on congenital spinal anomalies are reviewed.
The etiology of hemiplegic cerebral palsy has been elucidated by surveys of affected children using CT. MR imaging has contributed to the more exact diagnosis of the nature and extent of hypoxic ischemic damage and allows the accurate estimation of the time of the insult. Serial MR imaging and MR spectroscopy may be useful for predicting the prognosis for cerebral palsy and neurodevelopmental delay. The damage caused by intrauterine infection is best appreciated on MR imaging, though CT is important in showing calcification. Similar considerations apply to tuberous sclerosis, and new observations may facilitate MR imaging diagnosis. Gadolinium-enhanced MR imaging is the most accurate modality for detection of tumor recurrence and metastatic spread. Enhancement due to reactions to and complications of surgery can usually be distinguished. The reliability of MR imaging in showing many congenital anomalies provides evidence of the incidence of these lesions and contributes to understanding the disordered embryology. Most of the changes described in inherited metabolic disorders are nonspecific, but they may suggest a particular diagnosis, and MR imaging is the most sensitive modality for monitoring progress. Lifesaving intervention for arteriovenous malformations involving the vein of Galen requires detailed noninvasive imaging for selecting the most effective approach. Technical developments in diffusion and in flow imaging promise to further increase our diagnostic capabilities and to limit the application of invasive techniques.
The advent of MR imaging in musculoskeletal radiology, coupled with advances in the past decade in the treatment of knee disorders, has fueled an explosion of interest in MR imaging of the knee. Evaluation of meniscal pathology has been central to this development. The accuracy of MR imaging in the diagnosis of meniscal tears is now well established; attention has more recently been focused on the prevalence, natural history, and clinical significance of other intrameniscal signal abnormalities, as well as on the postoperative meniscus. Nonmeniscal knee disorders that may clinically mimic meniscal lesions are also reliably diagnosed with MR imaging. Technical advances in pulse sequences allow knee imaging with enhanced accuracy and efficiency.
This paper discusses the role of color Doppler ultrasonography (CDU) as it applies to the genitourinary tract. CDU is beneficial in evaluating both the native and allograft kidney in the diagnosis of renal arterial and venous stenosis, arteriovenous fistulas, pseudoaneurysms, arterial and venous thrombosis, and in the characterization and staging of renal masses. CDU has redefined the role of ultrasonography in the evaluation of the scrotum as it relates to testicular torsion, inflammatory disorders and varicoceles. Early results of CDU in prostate carcinoma and benign prostate hypertrophy have shown limited success. Identifying and assessing the neurovascular bundle may have an impact on the staging of prostate carcinoma. It is hoped that the future addition of ultrasound contrast agents will further establish the role of color Doppler in the diagnosis of a variety of genitourinary diseases and disorders.
The challenge of this "decade of the brain" is to perfect the interventional means for detecting and treating vascular malformations. The prognosis for patients with aneurysms is improved with the introduction of the new Guglielmi detachable coils. Parent vessel occlusion is a good alternative for treating dysplastic aneurysms at the circle of Willis after functional testing. Vein of Galen malformations of the mural type are best treated using the arterial route. The venous route is useful for treating choroidal forms when treatment by the arterial approach fails. These advances have resulted in significant improvement in the outlook for children with these conditions. Arteriovenous malformation embolization with either particles or glue has about a 10% permanent complication rate and, when combined with radiosurgery or surgical resection, is successful in curing 74% of patients. Morphologic features within the arteriovenous malformation are statistically useful markers of clinical course (hemorrhage and steal). Carotid cavernous fistulas can now also be treated by microcatheter and coils through the arterial or venous routes. Angioplasty in the neck and intracranially results in improved cortical perfusion. With technologic improvements and better case selection, serious complications can be minimized.
The past ten years have seen the introduction of a number of new techniques for the treatment of biliary diseases. In this report, we discuss the roles of both extracorporeal shock-wave lithotripsy and percutaneous treatment of gallstones, and we emphasize the changing role of these techniques since the advent of laparoscopic cholecystectomy. The literature on chemical cholecystectomy is reviewed with particular reference to experience in humans. Biliary endoprosthesis using expandable metallic stents is discussed in patients with benign and malignant biliary obstruction. Finally, we review the role of interventional radiologic procedures on liver transplant patients.
