|AIDS||Acquired immunodeficiency syndrome|
|CBC||Complete blood cell count|
|CHF||Congestive heart failure|
|CNS||Central nervous system|
|Diff||Differential cell count|
|EDTA||Ethylenediaminetetraacetic acid (edetate)|
|ELISA||Enzyme-linked immunosorbent assay|
|HLA||Human leukocyte antigen|
|INR||International Normalized Ratio|
|MRI||Magnetic resonance imaging|
|NPO||Nothing by mouth (nil per os)|
|PCR||Polymerase chain reaction|
|PMN||Polymorphonuclear neutrophil (leukocyte)|
|PO||Orally (per os)|
|RBC||Red blood cell|
|RPR||Rapid plasma reagin (syphilis test)|
|SIADH||Syndrome of inappropriate antidiuretic hormone (secretion)|
|SLE||Systemic lupus erythematosus|
|VDRL||Venereal Disease Research Laboratory (syphilis test)|
|WBC||White blood cell|
Information in this chapter is arranged anatomically from superior to inferior. It would not be feasible to include all available imaging tests in one chapter in a book of this size, but we have attempted to summarize the essential features of those examinations that are most frequently ordered in modern clinical practice or those that may be associated with difficulty or risk. Indications, advantages and disadvantages, contraindications, and patient preparation are presented. Costs of the studies are approximate and represent averages reported from several large medical centers.
Although intravenous contrast is an important tool in radiology, it is not without substantial risks. Minor reactions (nausea, vomiting, hives) occur with an overall incidence between 1% and 12%. Major reactions (laryngeal edema, bronchospasm, cardiac arrest) occur in 0.16–1 cases per 1000 patients. Deaths have been reported in 1:40,000 to 1:170,000 cases. Patients with an allergic history (asthma, hay fever, allergy to foods or drugs) have a slightly increased risk. A history of allergic-type reaction to contrast material is associated with an increased risk of a subsequent severe reaction. Prophylactic measures that may be required in such cases include corticosteroids and H1 and H2 blockers.
In addition, there is a risk of contrast-induced renal failure, which is usually mild and reversible. Persons at increased risk for potentially irreversible renal damage include patients with preexisting renal disease (particularly diabetics with borderline renal function), multiple myeloma, and severe hyperuricemia.
Contrast agents used in MRI are different from those used in most other radiology studies. Most MRI contrast agents are teratogenic and relatively contraindicated in pregnancy. Rarely, patients with severe renal dysfunction, ...