Contrast Medium Reduction with AlluraClarity for Iliac/Peripheral and EVAR procedures

The AlluraClarity system has been developed by Philips Healthcare. The
AlluraClarity is a novel X-ray imaging technology, successor of the previous
family of angiography systems, Allura Xper. Radiation dose reduction using
AlluraClarity technology has already been investigated in many clinical domains
by comparing it to the state-of-the-art reference Allura Xper. In iliac
procedures, patient radiation dose reduction of 83% during DSA has been
reported, with procedural patient radiation dose reduction of 57% for EVAR and
73% for iliac, at similar procedure complexity. Diagnostic and interventional
procedures use contrast media. Contrast medium induced nephropathy is
considered an important cause of hospital acquired renal failure. The goal of
the study is to validate the hypothesis that it is possible, based on the
relationship between image quality, patient radiation dose and parameters
affecting contrast medium, to find a compromise among them in order to reduce
the administered volume of contrast medium injected, at the expense of patient
radiation dose, while maintaining clinically acceptable image quality.

Primary objective:
- to compare the amount of contrast medium required to perform iliac/peripheral
and EVAR procedures using the AlluraClarity control settings and the study
settings, at similar procedure complexity, quantified as fluoro time, number of
DSA images and number of DSA runs

Secondary objectives:
- to demonstrate that study settings and diluted contrast medium injection
protocols for DSA can be used for an entire procedure (i.e. prove that the
physician never switches back during the procedure to control settings and the
standard contrast medium injection protocol)
- to evaluate the change in radiation dose required to minimize contrast medium
usage for the new proposed study settings

The study is divided in three phases:

Phase 0 is a prospective un-blinded cohort study. The current AlluraClarity
acquisition settings will be further tuned to investigate whether a further
reduction in patient radiation dose can be achieved. Tuning of the acquisition
settings will be done by an IQ specialist together with the interventional
radiologist. The tuning is a regular Philips process. Images will be grabbed
via an image grabber which is property of Philips. These images are grabbed at
the detector and contain raw images (de-identified). The new acquisition system
settings (referred to as *control settings*) will be used with standard
injection protocol (referred to as *SIP injection*).
Phase 0 is needed to define the starting point of the study and reduce the
radiation dose if possible. It is possible that lower dose than currently used
in the lab is not possible. In that case, Phase 0 will be immediately
terminated.

Phase 1 is a prospective un-blinded cohort study. Starting with the control
settings as defined in Phase 0 and SIP, the AlluraClarity will be tuned to
achieve contrast medium reduction at the expense of patient radiation dose.
Tuning of the acquisition settings will be done by an IQ specialist together
with the interventional radiologist. In this phase, on the same AlluraClarity
system, control and study settings will be made available
Phase 1 will be evaluated using a double DSA injection on the same patient.
Injection 1 will be acquired with control settings and standard injection
protocol, injection 2 will be acquired with study settings and diluted
injection protocol. The expectation is to dilute contrast medium in small
steps, combined with a dose increase for every new tuning step. The increase in
patient entrance dose will never exceed the boundary of the previous family of
X-ray systems, Allura Xper. It has been reported in peer reviewed journals that
AlluraClarity reduces the patient radiation dose with 83% in DSA for peripheral
procedures, with procedural patient radiation dose reduction of 57% for EVAR
and 73% for iliac, at similar procedure complexity. To avoid learning bias, the
order of injection 1 and 2 will be performed based on a randomization table.
The randomization table will be generated before start of the trial from a web
based application such as Research Randomizer (https://www.randomizer.org/) or
similar, and stored in the investigational brochures so that it is easily
accessible by the staff before a procedure starts to define the allocation of
the subject to the right treatment arm.
During this phase, the field of view will be appropriately collimated, as per
standard of care. The projection angle will be selected from most commonly and
universally used projections in clinical practice, allowing assessment of both
small and large vessels. The injections will be made with a one-minute pause to
ensure clearance of contrast agent from the vasculature and without modifying
the table position, C-arc position, detector format, detector position,
collimator, wedge position, or catheter position. In this way, only the
acquisition settings and injection protocol will be the variables. The images
will be grabbed via an image grabber which is property of Philips. These images
are grabbed at the detector and contain raw images (de-identified). As part of
the tuning phase, the physician will assess the images side-by-side to make
sure that there is no loss of information due to lower contrast medium
injection.

Phase 2 is a prospective un-blinded randomized controlled group trial with two
treatment groups (i.e., study group with study settings and diluted contrast
medium injection protocol as defined in Phase 1 and the control group with
control settings as defined in Phase 0 and standard injection protocol). The
randomization table will be generated before the start of the trial from a web
based application such as Research Randomizer (https://www.randomizer.org/) or
similar, and stored in the investigational brochures so that it is easily
accessible by the staff before a procedure starts to define the allocation of
the subject to the right treatment arm. The interventional radiologist will
remain un-blinded as the physician cannot be blind to the acquisition settings
for phase 2 as a different injection protocol has to be used based on the
selected settings. However, the physician will be blind to the selection
process as a different department is responsible of the patient planning in the
labs. The aim is to compare the two groups in terms of procedural contrast
medium used and procedural patient dose in relation to procedural complexity
(quantified by fluoroscopy time, number of DSA images and number of DSA runs).
In addition, the acquisition settings used by the physician during the DSA
acquisitions will be tracked to assess whether the physician ever switches back
to control settings when patients should be treated with new acquisition
settings (according to the randomization table). The reasons for switching back
will also be tracked in the e-CRF. Also in this phase, the images will be
grabbed via an image grabber which is property of Philips. These images are
grabbed at the detector and contain raw images (de-identified).

not applicable

In Phase 1 patients will be evaluated using a double DSA injection. Injection 1
will be acquired with control settings and standard injection protocol;
Injection 2 will be acquired with study settings and diluted injection
protocol. The expectation is to dilute contrast medium in small steps combined
with a dose increase for every new tuning step. The increase in patient
entrance dose will never exceed the boundary of the previous family of -ray
systems, Allura Xper.
The results of the study will provide new acquisition settings that can be used
with diluted injection protocol. This will benefit patients that have currently
no possibility of being treated because at risk of contrast induced nephropathy
to have access to the angiolab.