Use of Electrical Impedence to Measure Lean Body Weight as a Determinant of the Dose of Contrast Media for Abdominal CT

Study Overview
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Brief Summary
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There are several different methods that can be used to determine the dose of iodinated contrast material for a CT scan. These include a standard fixed dose, a dose based on total body weight, a dose based on body mass index, a dose based on lean body weight, and a dose based on estimated lean body weight. The fixed dose method uses a predetermined amount of contrast material for all patients having a CT scan of the abdomen regardless of size. This is the standard procedure currently used at Duke. The other methods use the patient's weight, either the total body weight or lean body weight, to determine the amount of contrast necessary for the CT exam. For this study, the investigators will use the fixed dose, total body weight, the lean body weight, and estimated lean body weight methods. The purpose of this study is to evaluate these five methods of determining the IV contrast volume and which may be best for abdominal CT scanning.

Official Title
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Use of Electrical Impedence to Measure Lean Body Weight as a Determinant of the Dose of Contrast Media for Abdominal CT

Conditions
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IV Contrast Dosing

Intervention / Treatment
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* Drug: Isovue 370
* Other: Weight calculation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: male or non-lactating, non-pregnant females 18 years or older who are able to give written informed consent Exclusion Criteria: a chronic underlying liver disease such as cirrhosis, fatty infiltration of the liver or glycogen storage diseases patients with a prolonged cardiac transit time such as those with a congested heart failure, a history of prior cardiac valve replacement, or restrictive/constrictive pericarditis patients having undergone any other radiological procedure utilizing iodinated contrast with the 24 hours prior to the CT exam patients above a certain total body weight (440 lbs.) due to limitation of the scales themselves (determined by manufacturer) any subjects with a history of hypersensitivity to iodine-containing compounds or renal insufficiency (serum creatinine >1.8) subjects with implanted electronic devices (pacemakers, defibrillators, insulin pumps, etc.)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Fixed dose<br>50 subjects will receive contrast media based on a fixed dose. Each will receive 125 mL of Isovue 370 (370 mg of iodine/mL) administered at 4 mL/sec (1.48 gmI/sec for 31.25 sec). | Drug: Isovue 370<br>* All contrast media doses administered for this study are within the FDA approved dose range in the package insert.<br>|
| Active Comparator: Total body weight<br>25 subjects will receive contrast media dose based on the total body weight. Total body weight will be determined. Both men and women will receive contrast media at a dose of 0.7 gmI/kg (1.78 mL of Isovue 370/kg) or 0.30 gmI/lb (0.81 mL of Isovue 370/lb). The injection rate will be 0.058 mL/sec/kg (0.026 mL/sec/lb). | Drug: Isovue 370<br>* All contrast media doses administered for this study are within the FDA approved dose range in the package insert.<br>Other: Weight calculation<br> <br> |
| Active Comparator: Calculated lean body weight<br>25 subjects will receive contrast media dose based on the calculated lean body weight. Total body weight and height will be determined. From this data the lean body weight will be calculated. Men will receive a dose of 0.86 gmI / kg LBW (2.32 mL of Isovue 370/kg at 0.074 mL/sec/kg) or 0.39 gmI/lb LBW (1.05 mL of Isovue 370/lb at 0.034 mL/sec/lb). Women will receive a dose of 0.92 gmI/kg LBW (2.49 mL of Isovue 370/kg at 0.080 mL/sec/kg) or 0.42 gmI/lb LBW (1.13 mL of Isovue 370/kg at 0.036 mL/sec/kg). | Drug: Isovue 370<br>* All contrast media doses administered for this study are within the FDA approved dose range in the package insert.<br>Other: Weight calculation<br> <br> |
| Active Comparator: Measured lean body weight<br>50 subjects will receive contrast media dose based on the measured lean body weight. Lean body weight will be determined using the Tanita body composition/analyzer scales. From this data the lean body weight will be calculated. Men will receive a dose of 0.86 gmI / kg LBW (2.32 mL of Isovue 370/kg at 0.074 mL/sec/kg) or 0.39 gmI/lb LBW (1.05 mL of Isovue 370/lb at 0.034 mL/sec/lb). Women will receive a dose of 0.92 gmI/kg LBW (2.49 mL of Isovue 370/kg at 0.080 mL/sec/kg) or 0.42 gmI/lb LBW (1.13 mL of Isovue 370/kg at 0.036 mL/sec/kg). | Drug: Isovue 370<br>* All contrast media doses administered for this study are within the FDA approved dose range in the package insert.<br>Other: Weight calculation<br> <br> |
| Active Comparator: Estimated lean body (eLBW) weight<br>25 subjects will receive contrast media dose based on the estimated lean body (eLBW) weight. Estimated lean body weight will be determined by using a unique software program which measures the sum of the posterior to anterior attenuation from the digital scout radiograph (abbreviated as sqrt PA) obtained during the standard planning scan of the abdominal/pelvic CT. Men will receive a dose of 0.86 gmI / kg eLBW (2.32 mL of Isovue 370/kg at 0.074 mL/sec/kg) or 0.39 gmI/lb eLBW (1.05 mL of Isovue 370/lb at 0.034 mL/sec/lb). Women will receive a dose of 0.92 gmI/kg eLBW (2.49 mL of Isovue 370/kg at 0.080 mL/sec/kg) or 0.42 gmI/lb eLBW (1.13 mL of Isovue 370/kg at 0.036 mL/sec/kg). | Drug: Isovue 370<br>* All contrast media doses administered for this study are within the FDA approved dose range in the package insert.<br>Other: Weight calculation<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in Enhancement of the Liver and Blood Vessels Over Time, Measured in Hounsfield Units (HU) | Operator-defined regions-of-interest (ROI) will be obtained from liver parenchyma, the portal vein and the abdominal aorta prior to contrast administration and on each slice through the liver post-contrast. Sum of all three areas reported as Summed measurement. | baseline, post-dose imaging (approximately 1hr) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in Volume of Contrast Used, Measured in Milliliters |  | baseline, post-dose imaging (approximately 1hr) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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IV contrast, contrast dosing