Optimization of Contrast Agent Dose in CT With Lean Body Weight

Patients will undergo a CT scan of abdomen (multi-phasic) with contrast agent and will be measured: total body weight (TBW), height, lean body weight (LBW) and body mass index (BMI) through formulas known in literature and with a balance for bioelectrical impedance analysis. There is no administration of drugs other than those indicated in the request of the treating physician.

Contrast agent dose:

IOPAMIRO® (Iopamidol) is an x-ray contrast medium of the new generation of non-ionic compounds, which are watersoluble because the molecular structure incorporates hydrophilic groups. Recommended dosage (ml) is 0.5-2.0/kg. Single injection volume depends on the vascular area to be examined.

IOMERON® (Iomeprolo) is an x-ray contrast medium of the new generation of non-ionic compounds, which are watersoluble because the molecular structure incorporates hydrophilic groups. Recommended dosage (ml) is 0.5-2.0/kg. Single injection volume depends on the vascular area to be examined.

Patients will be randomly assigned to undergo one of the two contrast agent protocols.

Control group (TBW protocol): patients will receive a contrast agent dose based on their TBW as a standard clinic protocol with a dose of 0.40 gI/kg of TBW. There are no differences compared to clinical practice.

Experimental group (LBW protocol): patients will receive a contrast agent dose based on their calculated LBW to test our hypothesis with a dose of 0.65 gI/kg of LBW, derived from our pilot study (LBW_01 approved 10/11/2016, registration number 160/int/2016).

If radiologists prefer a more enhanced examination, only scanning with contrast agent will be repeated with the standard dose as the standard clinical protocol.

• Iopamidol (Drug), also known as Iomeprolo: Contrast agent will be adrministered intravenously using total body weight or lean body weight, calculated with bioelectrical impedance analysis balance.

Primary outcomes

• Contrast Enhancement [1 day]: The liver contrast enhancement (ΔCEL) will be calculated as the difference between the CT value measured in the venous phase and that measured before contrast injection.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Patient ≥ 18 years of age;
* Patients who will perform a contrast-enhanced abdominal CT multi-phasic in our institutions;
* Patients able to give informed consent.

Exclusion Criteria:

* history of chronic underlying liver disease (cirrhosis, fatty infiltration of the liver, or glycogen storage disease);
* history of chronic underlying heart disease (congestive heart failure, prior cardiac valve replacement, restrictive and/or constrictive pericarditis);
* multiple myeloma;
* hypersensitivity to iodine-containing compounds;
* renal insufficiency (serum creatinine level ≤ 1.8 mg/dL \[159.12 µmol/L\]) or patients with renal failure (eGR <30 ml/min/1.73 m2);
* patients with antecubital vein that, at medical evaluation, cannot sustain the flow rate of CA injection (see below);
* patients carrier of prosthesis or metal bullets, pacemaker or stimulators;
* patients with liver diseases that affect the entire parenchyma;
* fragile patients which, after radiologist evaluation, require lower dose of CA;
* pregnancy;
* general contraindications to CT examination or reasoned decision of the radiologist.