CT Angiography

Contrast-Enhanced Helical CT for Diagnosis of Pulmonary Embolism

The diagnosis of Pulmonary Embolism has been revolutionized with the development of helical multidetector CT.  This technological development allows significantly faster imaging at thinner sections, preventing breathing artifacts and enabling contrast bolus timing in the pulmonary arteries.  Additionally, digital rather than film review of the images in stack mode on a computer display has also been important in the feasibility of this method. 

CT Pulmonary Angiography is now the gold standard for diagnosis of pulmonary embolism.  It is faster and more definitive than traditional V/Q nuclear scan technique.  It is also more sensitive and specific than the previous gold standard, conventional pulmonary angiography, which is now reserved for when interventions such as thrombolysis are indicated.  V/Q scan is now the backup technique for diagnosis of individuals that cannot undergo CT Pulmonary Angiography because of limited renal function or a history of major reaction to IV iodinated contrast.  [Incidentally, shellfish allergy or "iodine allergy" are not contraindications.  Read more about Iodine Allergies.]  In pregnant patients, CT pulmonary angiography remains the best method for diagnosis of PE since fetal radiation dose is less than with V/Q scan at any age of gestation.  [Winer-Muram HT, et al.  Pulmonary embolism in pregnant patients: fetal radiation dose with helical CT.  Radiology. 2002 Aug;224(2):487-92.]

CT Pulmonary Angiography is performed with IV contrast using a helical CT unit.  The study is available at St. Joseph's Hospital and at SDI's South Tampa and Oldsmar locations.