ventilation-perfusion scan

scan (skan)

1. to examine or map the body, or one or more organs or regions of it, by gathering information with a sensing device.

2. the data or image so obtained.

3. shortened form of scintiscan.

---

A-scan  display on a cathode ray tube of ultrasonic echoes, in which one axis represents the time required for return of the echo and the other corresponds to the strength of the echo.

B-scan  display on a cathode ray tube of ultrasonic echoes, depicting time elapsed and echo strength and producing two-dimensional cross-sectional displays by movement of the transducer.

CAT scan , CT scan computed tomography, or the image obtained from it.

M-mode scan  the image obtained using M-mode echocardiography, showing the motion (M) over time of a monodimensional (“icepick”) section of the heart.

PET scan  positron emission tomography, or the image obtained from it.

ventilation-perfusion scan , V/Q scan a scintigraphic technique for demonstrating perfusion defects in normally ventilated areas of the lung in the diagnosis of pulmonary embolism.

---

ventilation-perfusion scan

n.

A diagnostic test for pulmonary embolism in which an x-ray of the lung records the distribution and perfusion of a radionuclide that is inhaled and a second radionuclide that is administered intravenously. Also called V/Q scan.

---

scan [skan]

1. to examine or map the body, or one or more organs or regions of it, by gathering information with a sensing device, such as a moving detector or a sweeping beam of radiation.

2. the data or image so obtained, often designated according to the organ under examination, such as a brain scan, kidney scan, or thyroid scan.

3. shortened form of scintiscan.

A-scan display on a cathode ray tube of ultrasonic echoes, in which one axis represents the time required for return of the echo and the other corresponds to the strength of the echo.

B-scan display on a cathode ray tube of ultrasonic echoes, in which the position of a bright dot on the tube corresponds to the time elapsed and the brightness of the spot to the strength of the echo; movement of the transducer across the skin surface yields a two-dimensional cross-sectional display.

CAT scan (CT scan) the image generated by computerized axial tomography.

HIDA scan a type of scan using a technetium 99m complex to assess hepatobiliary function.

thallium scan a scintiscan involving use of thallium 201; see also thallium scan.

ventilation-perfusion scan (V/Q scan) a scintigraphic technique for demonstrating perfusion defects in normally ventilated areas of the lung in the diagnosis of pulmonary embolism, consisting of the imaging of the distribution of an inhaled radionuclide followed by the imaging of the perfusion of the lungs by an injected radionuclide.

---

ventilation-perfusion scan

Radionuclide scan of lung, V/Q scan Cardiology, Pulmonology A noninvasive radionuclide test that provides functional information as a ratio of pulmonary ventilation–V to blood flow–perfusion, Q through the lungs; in one common protocol, the scan is performed after inhaling 133Xe –20 mCi, 148 MBq and IV injection of 99mTc microacroaggregated albumin, for assessing inspiratory airflow, lung volume, air trapping and adequacy of perfusion; 'indeterminant' studies are not uncommon, and are more frequent in those with underlying lung disease. See Lung volumes, Pulmonary panel.