Multiple Pulmonary Emboli Clinical Trial
Official title:
Efficacy Of Low(30 Ml) Versus Full Dose (100 Ml)Contrast CT Pulmonary Angiography Performed On 64 Multi-Detector CT In Detecting Emboli
With the improvement in CT scanners and injectors, diagnostic chest CT can now be performed in less than 10 seconds. It was hypothesized that diagnostic CT pulmonary angiograms could be done with less than the usual 80-120 ml of contrast used. We have developed a method of performing diagnostic CT pulmonary angiograms with 30 ml of intravenous contrast in most patients. The long-term objective of this study is to show that there is no difference in the diagnostic efficacy of this low dose 30 ml technique when compared to the more traditional full-dose technique.
Potential participants in the study will have been referred to the radiology section for a
CTPA for a suspected pulmonary embolus. The radiologist will review the patient's record in
CPRS, as is done routinely in this situation. Patients with class 3 or 4 CHF,
supraventricular tachycardia, Serum Creatinine >1.5 mg/dl (>1.3 mg/dl female), history of
contrast allergy, or unable to give informed consent will be excluded from both arms of the
study. Patients with serum creatinine >1.28 mg/dl require referring physician approval. If
the participant appears to qualify for the study then the study physician will contact the
referring physician and inform him/her of the study. If the referring physician is agreeable
then either the radiologist or the referring physician will approach the patient, either at
the bedside or in the radiology clinic to determine if the patient is interested in
participating in the study. If so, a study radiologist will begin the informed consent
process. After informed consent is obtained the subject will be computer randomized to
either the new low-dose or full-dose technique protocols. A total of 220 studies (110 per
group) will be performed.
Multidetector CT Scan: All CT examinations will be performed on the Siemens Sensation
64-MDCT scanner. Visipaque (Iodixanol) 320 non-ionic isoosmolar contrast agent will be used
in all contrast examinations followed by a subsequent injection of normal saline. An
informed written consent for the injection of IV contrast will be obtained prior to all CT
examinations. Safe venous access will be obtained via either an antecubital vein or a
central venous line. For low dose CT pulmonary angiograms, 30 ml of IV Radio Contrast
Material (RCM) will be injected at a flow rate of 5 ml/second followed by an injection of 20
ml of normal saline at 5ml/second. The region of interest (ROI) will be the superior vena
cava (SVC) at the approximate level of the aortic arch. The scan will be triggered to begin
at 75 Hounsfield units (HU). For Full dose CT pulmonary angiograms, 100 ml of IV RCM will be
injected at a flow rate of 5ml/sec. The ROI will be the main pulmonary artery. The scan will
be triggered at 120 HU. One mm contiguous axial spiral scans will be obtained from the apex
of the lung through the adrenals. Reformatted 1.5 mm axial, 3 mm axial, 1.5 mm coronal and
sagittal images will be obtained. All images will be uploaded to the AGFA Picture Archiving
Communication System (PACS) workstation for interpretation. The costs of all CT scans and
RCM will be covered by the Department of Imaging as the majority of the studies are part of
routine clinical care.
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Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Outcomes Assessor), Primary Purpose: Diagnostic