Table 2. Alternative use of contrast media


Procedure Alternative agents Gastrostomy/gastrojejunostomy Gastrostomy leaking/obstructed drains that require exchanges Percutaneous nephrostomy


Dialysis access interventions—Elective Lymphangiogram/embolization Transjugular liver biopsy


Transjugular intrahepatic portosystemic shunt (TIPS) creation for diuretic-refractory ascites


Routine tube exchanges (including gastrostomy tubes) IVC filter placements


Fallopian tube recanalization Pulmonary embolism


Alternative contrast agents for IR Current recommendations for alternative contrast agents for vascular and nonvascular procedures are listed in Table 2. While gadolinium (Gd) is currently “off-label” for intra-arterial use, literature exists that supports its use, as well as significant, broad clinical experience.2


Gd use in angiography The use of Gd either in place of or in addition to another method of imaging is a strategy that may be employed to minimize the use of iodinated contrast. Dose limitations may limit the use of Gd as a solo imaging agent, but it can serve as an adjuvant or confirmatory agent after IVUS or CO2


suggest a pathology.


Multiple studies have demonstrated the safe use of Gd administration in patients with renal insufficiency when used for MRI. This can be extrapolated for use in angiography. The recommended dose of Gd for adults and children (2 years and older) is 0.1 mL/kg body weight (0.1 mmol/kg) during MRI. For example: a 90 kg adult will have a maximum of 9 mL of Gd.


Studies recommend that the use of less than 0.3–0.4 mmol/kg body weight is associated with low risk of nephrotoxicity.3,4


CO2


Lipiodol CO2


CO2 ICE


Room air/Gastrografin/Cystografin IVUS, CO2


Lipiodol Lysis rather than mechanical thrombectomy


Familiarity with CO2 delivery systems is


required to avoid room air contamination and resultant air embolism.


dialysis is less effective requiring three weeks to clear 70%.


The low concentration (0.5 mmol/ml) of Gd agents, and the recommended total dose limits of Gd (0.3–0.4 mmol/kg), pose a limitation for image quality in angiography. When considering Gd for diagnostic angiography, it is important to consult with your local physicist to optimize image quality in fluoroscopic systems, given the differences of gadolinium K-edge (50.2 KeV) as compared to iodine (33 KeV).5


This requires imaging with a higher range of kilovoltages (77–96 KVp) compared to iodine studies. Imaging should be performed using digital subtraction angiography (DSA) and full- strength Gd within small- to medium- sized vessels to maximize visualization. Careful planning is required to best utilize the limited volume of gadolinium that can be used for a given procedure.


In patients with


renal insufficiency, Gd can be removed from the blood pool after three hemodialysis sessions; peritoneal


22 IRQ | SUMMER 2022


Carbon dioxide (CO2) in angiography The use of CO2


as an alternative to iodinated CM has long been used


in dialysis procedures6 nephrotoxic. CO2


as it is not replaces the blood


volume, expands, and has little to no capillary phase, which may have a better ability to detect arterial bleeding as well. It is also highly buoyant, preferably opacifying nondependent vessels, which is beneficial to visualize anterior structures. It can be used via slow injection for numerous venous procedures. There is no dose limit to its use and therefore it can be used liberally.


CO2 outperforms iodinated CM in several


situations as well due to its ultra-low viscosity and subtotal blood volume displacement: improved demonstration of collateral vessels, occult sites of GI bleeding and visualization of portal- splanchnic veins.


Familiarity with CO2 delivery


systems is required to avoid room air contamination and resultant air embolism. Due to the buoyancy of CO2


Room Air/CO2/Gastrografin


Hand injection of 6–10 ml of Gd and/or CO2 Pediatric doses limit to 0.1 mmol/kg of Gd


, air trapping can result in organ


ischemia. “Vapor lock” occurs when nitrogen and oxygen gases become trapped with CO2


with a pocket such


as a pseudoaneurysm or the IMA from an aortic aneurysm resulting in a gas pocket and resultant obstruction.


To prevent trapping, excess CO2 administration should be limited and


volumes should be less than 100 mLs per injection. A 30 mL bolus fully dissolves within 30–60 seconds; therefore bolus administration


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48