Isovue 300

A cylindrical water phantom (30 cm diameter, 35 cm length) with a 13 cm open bore was used to simulate the attenuation of a standard patient. A 3D-printed holder was used to suspend test vials along the center axis of the bore. Ten vials containing iodinated contrast media in deionized water with concentrations of 0.125, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 2.0, 4.0 and 8.0 mg I/mL (Isovue 300, Bracco Diagnostics, Melville, NY) and total volume 5 mL and a vial with distilled water were all placed in the holder within the phantom. The phantom was scanned at all four dose levels. The thicker 2 mm slice thickness was used to reflect common clinical applications.
ROIs (36.5 × 6.4 × 9.0 mm³, volume of 2.1 cm³) were drawn in each vial and the mean and standard deviation of pixel values were calculated. The ROI dimensions were selected to include as much of the solution in the vial as possible. The mean values in each iodine vial were used to calculate contrast while the standard deviation of the water vial was used to calculate noise. CNR was evaluated by dividing these quantities. The Rose criterion (22 , 23 ), which provides a CNR value of five as needed to distinguish features, was applied with 2.5 as a as reference level for iodine detectability.

RC refers primarily to iohexol (Omnipaque 300; GE Healthcare; Princeton, NJ) which is categorized as a low osmolality (672 mOsm/kg water), nonionic, iodinated (300 mg/iodine/ml) contrast medium. A second RC iopamidol (Isovue 300; Bracco Diagnostics; Monroe Township, NJ) which is in the same category as iohexol, was used to verify key findings from the study, and its use is specified in the text. NFAT-luciferase (Qiagen; Valencia, CA), NF-κB-luciferase (Vector Biolabs; Philadelphia PA), and constitutively active calcineurin (ΔCn) adenoviruses were constructed as previously described ^{10 (link)–12 (link)}. All other reagents were purchased from Sigma-Aldrich (St. Louis, MO), unless specified otherwise. Male Swiss Webster mice (Jackson Laboratories, Bar Harbor, ME) weighing 22–28 g were fed standard laboratory chow and given free access to water. CnAβ−/− mice were of the B6129J/F1 strain and were generated by Dr. J. Molkentin ^{13 (link)}. Age-, sex-, and strain-matched control mice were used as wild-type (WT) controls. All animal experiments were performed using a protocol approved by the University of Pittsburgh Institutional Animal Care and Use Committee.

The CTA studies of the carotid arteries were performed on 16- or 64-slice computed tomography scanners (GE Healthcare, Milwaukee, Illinois) and (Siemens Healthcare, Erlangen, Germany) in helical mode. The carotid artery CTA, covering the midchest to the vertex of the brain, was collimated at 1 to 1.25 mm using 120 kVp and 240 mAs, and a rotation time of 0.6 to 0.8 second. A bolus of 70 to 80 mL of Isovue 300 or 370 (lopamidol; Bracco Diagnostics Inc, Monroe Township, NJ) was injected into an antecubital vein with a power injector at a rate of 4 to 5 mL/s. SmartPrep protocol was applied to monitor the contrast enhancement and trigger the CTA acquisition. Effective dose associated with the carotid artery CTA protocol was 5 to 7 mSv.