CT Diagnosis of Acute Pulmonary Embolism

Multidetector Computed Tomography Pulmonary Angiography Pitfalls in the Evaluation of Pulmonary Embolism With Emphasis in Technique

“…43 Iodine concentration, flow rate, and iodine delivery rate are critical protocol-specific factors to achieve ideal vascular attenuation. [23][24][25] Although there are conflicting results comparing different iodine contrast concentrations, an adequate study typically require 350-400 mg/mL and injection rates between 4 and 6 cc/s, which would result in iodine delivery rate of more than 1.2-1.3 g/s. 9,38,44,45 Typically for a 4-16-slice MDCT scanner, the volume of contrast used is about 100-150 mL, whereas for 64-slice MDCT scanners, 80-100 mL is commonly used.…”

“…14,[24][25][26][27] However, as with single-slice CT, early-generation MDCT scanners require reconciliation of the longitudinal spatial resolution with the duration of the apnea. The aim is to image at the thinnest collimation the patient breath holding allows.…”

“…Incorrect breathing because of poor training, extended inspiration, or a sudden Valsalva maneuver may render the study noninterpretable, especially with shorter acquisition times. 9,25 Flow-Related Artifact…”

“…25 The shorter acquisition times with the latest-generation MDCT scanners create a new challenge, in that the study requires a meticulous timing plan to ensure images are obtained during the peak enhancement. In principle, the scan delay plus the scan time should equal the duration of the contrast injection.…”

“…The "seagull sign" 28 related to curvilinear composite images of the vessels may be seen. 25,28,29 The most sensitive way to identify motion artifact is by reviewing the lung windows. 30 With early-generation MDCT scanners, caudocranial scanning continues to be an option when longer breathhold times are anticipated as respiratory motion is typically less at the lung apices.…”