Chest Flashcards
CT scans of the chest for disease progression should extend inferiorly through what anatomy?
adrenal glands (a common site for metastatic deposit)
For CT of the lungs/mediastinum, what would be the recommended kVp, mA, and slice thickness?
120 kVp, 40-300 mA, 3-5 mm slice thickness
What are sample WL and WW for lung parenchyma, mediastinum, and bone?
parenchyma: WL -450, WW 1400
mediastinum: 40, 350
bone: 300, 2000
For High Resolution CT of the lungs, what is a sample slice size and spacing?
thin slices of 1-2 mm; separated by 10-15 mm
What is the primary indication for HRCT of the Lungs? What are some examples of that?
Diffuse lung disease:
Chronic Obstructive Pulmonary Disease (COPD), Emphysema, Cystic Fibrosis, and Asthma
Patients with _________ can be scanned after full EXpiration.
air trapping (small airway disease)
CT Pulmonary Angiography is commonly called what?
CTA PE
For a CT Pulmonary Angiography study, what direction is the patient scanned? Why?
a. caudocranial
b. if pt cannot hold breathe for entire scan, streaking from lung movement is limited as the scan progresses superiorly; AND there is less streaking from the contrast in the SVC
What is a sample technique for CTPA?
a. 120 kVp, 400 mA, 0.8 sec
b. 0.75 mm slice overlap
c. 0.625 mm collimation
What is “Prospective Gating (Triggering)”?
when using a ECG, the heart rate is read and scans are only made during periods of diastole
What is “Retrospective Gating”?
when using a ECG, scanning throughout the entire cardiac cycle and choosing which images to keep/recon based on the selected cardiac cycle
What is a technical limitation of a Coronary Artery Calcium CT?
inability of CT to differentiate between calcium and noncalcified atherosclerotic plaque
What portion of the ECG does scanning occur during a CT Calcium study?
during the T wave
What minimum size and HU must a calclification be to be scored?
1 mm squared; 130+ HU
What are the four levels of calcium scoring?
minimum: 1-10
mild: 11-100
moderate: 101-400
extensive: 401+
What anatomy must be included on a CT Calcium Study?
the aortic arch through the cardiac base
What heart rate yields the best results for a CT Calcium Study?
slow and steady; below 65-75
What is temporal resolution? How is it related to gantry rotation time?
temporal resolution is how well the CT was able to “freeze” the motion of the heart and its arterial motions;
gantry rotation time describes the time for the gantry to make one rotation. example: if the GRT is 300 msec, the temporal resolution is 300 msec.
What is Half-Scan Reconstruction for CT Calcium Study?
the gantry rotates fast enough to scan the entire heart in half of a rotation. Because of this, the temporal resolution would be half of one rotation time
What drug can be given to the patient to dilate the coronary vessels? Why would this help the image/scan?
nitroglycerine; dilating the vessels improves the spacial resolution
At what point of the ECG is the heart moving the least?
about 55-75% of the R-R interval; about midpoint of diastole
When reconstructing a CT Calcium Study, what planes of the heart should the sagittal and coronal be based off?
off of the long and short axes of the heart
Which CT of the chest is considered a “fly-through”? What else is it called?
Bronchography or “virtual bronchoscopy.” Used to visualize the bronchial tree; also, 3D recons are utilized
What is the only absolute contraindication for a CTA Coronary?
contraindication for IV contrast
A pulmonary nodule is defined as a high density focal spot on the lung measuring at up to ___ cm in diameter
3 cm
A _____ _____ on a lung is defined as a high density focal spot measuring more than 3 cm in diameter
focal mass
Define ejection fraction.
the quantity of blood pumped out of a ventricle every heartbeat
