Items in AFP with MESH term: Magnetic Resonance Imaging
ABSTRACT: Risks of diagnostic imaging include cancer from radiation exposure and nephrogenic systemic fibrosis. The increase in volume of imaging between 1980 and 2006 has led to a sixfold increase in annual per capita radiation exposure. It is predicted that 2 percent of future cancers will be caused by radiation from computed tomography (CT) exposure. Gadolinium contrast media should be avoided in patients with stage 4 or 5 chronic kidney disease because of the risk of nephrogenic systemic fibrosis. Appropriate use of imaging based on guidelines for specific clinical conditions can reduce these risks. Although noncontrast CT of the head is needed to rule out bleeding in patients with suspected stroke within the first three hours of symptom onset, diffusion-weighted imaging with magnetic resonance of the head and neck is superior to CT within three to 24 hours of symptom onset. Headache merits neuroimaging in special circumstances only. Sestamibi radioisotope has less radiation than thallium for myocardial perfusion imaging. Use of intravenous contrast media with abdominopelvic CT significantly increases the diagnostic accuracy for appendicitis. Cholescintigraphy has better discrimination to diagnose acute cholecystitis than CT in patients with equivocal ultrasonography results. Limited three-view intravenous urography is recommended in pregnancy to evaluate urolithiasis if initial ultrasonography findings are negative or equivocal. Given that many asymptomatic adults have abnormal findings on lumbar spine magnetic resonance imaging, this modality generally should not be performed for nonspecific chronic low back pain in the absence of red flags. Whole body scanning is not supported by current evidence.
ABSTRACT: Patients with wrist pain commonly present with an acute injury or spontaneous onset of pain without a definite traumatic event. A fall onto an outstretched hand can lead to a scaphoid fracture, which is the most commonly fractured carpal bone. Conventional radiography alone can miss up to 30 percent of scaphoid fractures. Specialized views (e.g., posteroanterior in ulnar deviation, pronated oblique) and repeat radiography in 10 to 14 days can improve sensitivity for scaphoid fractures. If a suspected scaphoid fracture cannot be confirmed with plain radiography, a bone scan or magnetic resonance imaging can be used. Subacute or chronic wrist pain usually develops gradually with or without a prior traumatic event. In these cases, the differential diagnosis is wide and includes tendinopathy and nerve entrapment. Overuse of the muscles of the forearm and wrist may lead to tendinopathy. Radial pain involving mostly the first extensor compartment is commonly de Quervain tenosynovitis. The diagnosis is based on history and examination findings of a positive Finkelstein test and a negative grind test. Nerve entrapment at the wrist presents with pain and also with sensory and sometimes motor symptoms. In ulnar neuropathies of the wrist, the typical presentation is wrist discomfort with sensory changes in the fourth and fifth digits. Activities that involve repetitive or prolonged wrist extension, such as cycling, karate, and baseball (specifically catchers), may increase the risk of ulnar neuropathy. Electrodiagnostic tests identify the area of nerve entrapment and the extent of the pathology.
Intracranial Lesion with Fever and Headaches - Photo Quiz