CRC critical reviews in diagnostic imaging最新文献

M. pneumoniae is a common cause of pneumonia. The diagnosis is suspected when the patient presents with symptoms suggesting primary atypical pneumonia including cough, fever, chills, headache, and malaise in association with a segmental or subsegmental pulmonary infiltrate(s), the white blood cell count is normal or only slightly elevated, and the Gram stain of the sputum (if any can be obtained) reveals polymorphonuclear leukocytes and few bacteria. The diagnosis is more difficult when the patient presents with symptoms not suggestive of pneumonia including lethargy, dyspnea, and a 1- to 4-week history of shortness of breath without cough or fever in association with diffuse reticulonodular or interstitial pulmonary infiltrates. The disease in the previously healthy host is usually benign and self-limiting. However, the course is shortened by the administration of tetracycline derivatives or erythromycin. M. pneumoniae pneumonia can occur in association with other diseases including sickle cell anemia, sarcoidosis, systemic lupus erythematosus, Hodgkin's disease, and various other immunodeficiency states. In these patients mycoplasma pneumonia can be very serious. Although there is no pathognomonic clinical or radiographic presentation, careful consideration of epidemiologic, clinical, laboratory, and radiographic data are usually sufficient to suggest the diagnosis in most patients.

The growing number of oncological patients subjected to radiogherapy require the diagnostic radiologist to be aware of expected bone changes following irradiation and the differentiation of this entity from metastasis. The primary event of radiation damage to bone is atrophy and true necrosis of bone is uncommon. The postradiation atrophic changes of bone are the result of combined cellular and vascular damage, the former being more important. The damage to the osteoblast resulting in decreased matrix production is apparently the primary histopathologic event. Radiation damaged bone is susceptible to superimposed complications of fracture, infection, necrosis, and sarcoma. The primary radiographic evidence of atrophy, localized osteopenia, is late in appearing, mainly because of the relative insensitivity of radiographs in detecting demineralization. Contrary to former views, the mature bone is quite radiosensitive and reacts quickly to even small doses of radiation. In vivo midrodensitometric analysis and radionuclide bone and bone marrow scans can reveal early changes following irradiation. The differentiation of postirradiation atrophy and metastasis may be difficult. Biopsy should be the last resort because of the possibility of causing true necrosis in atrophic bone by trauma and infection.

Xeroradiology has been reviewed from the earliest description of charged powder imaging by Lichtenberg in 1977 through its more recent development and widespread use. The principles of photoconductivity, selenium characteristics, and edge enhancement were explained, and the basic components and operation of xeroradiographic equipment were outlined. Xeroradiography has achieved its greatest usefulness in mammography and the evaluation of breast disease. Although early workers in the field were discouraged by the relatively primitive nature of the equipment, Wolfe, by his persistent investigation, demonstrated the value of xeroradiography. He proposed the following advantages over film mammography: ease of interpretation; more information on one image; a more rapid, dry developing process; less irradiation required than nonscreen industrial type film; and probably greater accuracy. Each of these factors were reviewed in detail, type film; and probably greater accuracy. Each of these factors were reviewed in detail, and the factors influencing dose reduction were elaborated. The application of xeroradiography to nearly every aspect of diagnostic radiology has been attempted. Areas of greatest effectiveness include the evaluation of the pharyngeal and laryngeal structures of the head and neck, foreign body detection in soft tissues, verification of radiotherapy beam coverage and treatment field, detection of soft tissue tumors and some bone tumors for soft tissue components, and visualization of the smaller skeletal structures of the extremities. Because of radiation dosage limitations, xeroradiography cannot, at present, be used for routine examinations of the thicker body portions, the chest, or the abdomen. Investigations are continuing into methods of increasing the sensitivity of the process, thereby hopefully significantly reducing the radiation dose and allowing more widespread use of xeroradiography in these areas.

Injury to the basal portion of the anterior, middle, and posterior fossae of the skull are rather easily overlooked unless the radiologist carefully searches for indirect or direct signs of such injury. Representative injuries of each area are reviewed and radiological signs are illustrated. Combination fractures transversing several areas are also considered and illustrated.

The use of diagnostic and therapeutic angiography for postoperative bleeding which began with its application for bleeding following GI surgery can be ezpanded to almost all other areas of the body. Severe postoperative hemorrhage that previously required a second operation can now be successfully managed by the use of intraarterial or intravenous vasoconstrictors or transcatheter occlusion, thus significantly reducing patient morbidity and mortality. In those patients where a reexploration becomes necessary, diagnostic angiogarphy is a useful guide and helps to tailor the operative procedures.