Seminars in nuclear medicine
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Review Comparative Study
Enhancing lung scintigraphy with single-photon emission computed tomography.
Although widely used for many years in the assessment of pulmonary embolism, planar ventilation-perfusion (V/Q) scintigraphy has well-recognized limitations. Single-photon emission computed tomography (SPECT) imaging, which can be readily performed in most modern nuclear medicine centers equipped with multihead gamma cameras, overcomes many of these limitations through its ability to generate 3-dimensional imaging data. V/Q SPECT has been shown to have a greater sensitivity and specificity than planar imaging and has a lower nondiagnostic rate. ⋯ It also involves significantly less radiation dose to breast tissue, an important consideration, particularly in young women. For the V/Q scan to remain relevant in the evaluation of patients with suspected pulmonary embolism, it is essential that image data are obtained so as to maximize their accuracy and diagnostic usefulness. V/Q SPECT can achieve this and, furthermore, may have a role in conditions other than pulmonary embolism, including both clinical and research fields.
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The role of ultrasonography of the lower extremities for the evaluation of patients with suspected pulmonary embolism has become more clearly defined with time. Ultrasonography is a useful first-line test for pulmonary embolism in clinical circumstances in which radiographic imaging is contraindicated or not readily available (eg, pregnancy). ⋯ Ultrasonography is helpful to exclude a diagnosis of deep vein thrombosis in patients who have nondiagnostic ventilation-perfusion scans. For patients with nondiagnostic ventilation-perfusion scans and negative ultrasonography who are considered clinically highly likely to have pulmonary embolism, it is recommended that computed tomography pulmonary angiography be performed.