CT of the Abdomen and Pelvis With Contrast Material Clinical Trial
Official title:
Clinical Trial of a Novel Evidence-Based Formula for Customizing the Contrast Media Dose and Rate Administered During Multidetector-Row CT (MDCT) Scanning of the Abdomen and Pelvis
1. To determine if a formula derived from PCA using specific patient parameters can be used
to determine the individual contrast material dose and provide a more consistent level
of vascular and parenchymal enhancement during MDCT scanning of the abdomen and pelvis.
2. Up to 500 adult patients referred for a "CT of the abdomen and pelvis with contrast
material" will be recruited to participate in this trial. Single CT axial slices (n=2)
will be obtained at the level of the L4 pedicle and the supra-acetabular pelvis using a
field-of-view that includes all of the patient. From patient measurements (height,
weight, body dimensions), a customized dose of contrast material will be specified
according to the derived formula for 400 subjects. One hundred subjects will receive the
usual fixed contrast dose.
3. Enhancement data in HU will be measured from the CT scans using manually-placed ROIs on
the upper abdominal aorta, main portal vein and liver parenchyma, avoiding visible liver
tumors, major blood vessels and artifacts, if present. This enhancement data will be
used to determine the patient-to-patient variability.
The next step is a single center, prospective clinical trial intended to test the hypothesis
that a formula derived from PCA using specific subject parameters can be used to determine
the individual contrast material dose and provide a more consistent level of vascular and
parenchymal enhancement during MDCT scanning of the abdomen and pelvis.
500 subjects referred for a "CT of the abdomen and pelvis with contrast material" will be
recruited to participate in this trial. Subjects in the first group of 200 will be randomized
to either a fixed dose of contrast material (100 subjects) or a customized dose of contrast
material based on the experimental algorithm (100 subjects). The second group of 300 subjects
will receive a customized dose of contrast material based on the experimental algorithm. All
of the subjects will be studied on a single CT scanner located in the Duke Cancer Center.
After obtaining informed consent, the subjects will first undergo measurement of their height
and weight on a dedicated pair of scales located in close proximity to the scanner.
The subjects will then be placed on the CT scan table in the supine position followed by the
acquisition of scout digital radiographs in both the AP and ML projections. These digital
scout radiographs are acquired routinely and used by the technologist to plan the scan. From
these scout radiographs, single CT slices in the axial plane (n=2) will subsequently be
obtained, one through the level of the L4 pedicle and the other through the supra-acetabular
pelvis using a field-of-view that includes all of the subject. These slices are not part of
the routine protocol but will be acquired using low radiation dose parameters. From these
measurements (height, weight and specific body dimensions), a customized dose of contrast
material will be specified according to the derived formula. Since the dose will be different
in every subject, the rate will need to be adjusted as well. This will be accomplished by
adjusting the rate so that the injection duration is the same in every subject. For example,
if the specified contrast material dose is 100 mL and the injection duration is 25 seconds,
the injection rate will be 4 mL/sec. If the specified contrast material dose is 125 mL and
the injection duration is also 25 seconds, the injection rate will be increased to 5 mL/sec.
Note that 100 subjects will receive a fixed dose and rate (150 mL of iopamidol with a
concentration of 300 mg of iodine/mL at an injection rate of 3 mL/sec for a total dose of 45
grams of iodine) and 400 subjects will be administered a customized dose and rate (X mL of
iopamidol with a concentration of 300 mg of iodine/mL at an injection rate of X mL/sec for a
total dose of X grams of iodine) and. Also note that for the customized dose group, the
maximum and minimum doses of contrast material will be 200 (75 gm iodine) and 75 (22.5 gm
iodine) mL, respectively and the maximum and minimum injection rates will be 6 and 2 mL/sec,
respectively. Because the injection rate in the customized group is variable, the nurse or
technologist establishing intravenous access may choose to use a larger or small caliber
angiocatheter than in the fixed group in order to accommodate a higher or lower injection
rate, respectively. The caliber of the angiocatheter as well as the venous access site will
be recorded along with the dose and rate of contrast material. The rate of administration of
contrast material is controlled by a mechanical power injector furnished by Nemoto Kyorindo
Co, Ltd. free of charge for use in this study.
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