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

Phase 4

Completed

Conditions: IV Contrast Dosing

Interventions: Drug: Isovue 370
Other: Weight calculation

Registration Number: NCT02170688

Lead Sponsor: Duke University

Brief Summary: 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.

Detailed Description: Not available

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 139

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.)

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Measured lean body weight	Weight calculation	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).
Estimated lean body (eLBW) weight	Weight calculation	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).
Calculated lean body weight	Weight calculation	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).
Total body weight	Weight calculation	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).
Fixed dose	Isovue 370	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).
Total body weight	Isovue 370	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).
Calculated lean body weight	Isovue 370	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).
Estimated lean body (eLBW) weight	Isovue 370	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).
Measured lean body weight	Isovue 370	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).

Primary Outcome Measures

Name	Time	Method
Difference in Enhancement of the Liver and Blood Vessels Over Time, Measured in Hounsfield Units (HU)	baseline, post-dose imaging (approximately 1hr)	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.

Secondary Outcome Measures