Magnetic Resonance flow measurements of mesenteric arteries and veins and portal vein with food stimulation and mitochondrial oxygen measurements during routine upper endoscopy in patients suspected of chronic gastro-intestinal ischemia

The diagnosis of chronic gastro-intestinal ischemia (CGI) remains a clinical
challenge because this diagnosis is difficult to distinguish by the frequent
incidence of chronic abdominal pain and asymptomatic stenosis of the mesenteric
arteries1.
The standard diagnostic work up includes medical history, anamnesis and
physical examination, radiological imaging and a functional test as visible
light spectroscopy (VLS)2-4 or tonometry5-7. A multidisciplinary team
consisting of a gastroenterologist, a vascular surgeon and an interventional
radiologist, all specialized in CGI, discusses all patients which results in an
expert based consensus diagnosis. Currently, there is no specific test to
diagnose CGI.
In literature, Magnetic Resonance (MR) techniques are described by which the
flow in the mesenteric vessels is measured pre- and post-prandial in healthy
volunteers and CGI patients8-12. The flow in the mesenteric vessels increases
postprandial (hyperemia). However, this increase in post-prandial flow compared
to pre-prandial appeared less in CGI patients compared to the healthy
volunteers. In some CGI patients, even a decrease of the post-prandial compared
to pre-prandial flow was seen.
We might be able to distinguish patients with CGI from patients without CGI
with MR flow measurements with food stimulation.
As mentioned it is standard practice to perform a functional test such as VLS
and tonometry, but both have limitations. An easy-to-use and accurate
functional test to diagnose CGI is highly desired. Protoporphyrin IX-triplet
state lifetime technique (PpIX-TSLT) is a novel method used to measure oxygen
in mitochondria13. After administration of 5-aminolevulinicacid (ALA)
mitochondrial PpIX increases. Green light is used to excite PpIX during the
measurements, inducing light emission. After collision with oxygen molecules
PpIX returns to its ground state, ceasing light emission. The duration of light
emission is measured. When few mitochondrial oxygen is present, collisions are
less likely to occur resulting in a longer duration of light emission. A
previous study has proven feasibility of endoscopic mitochondrial oxygen
measurements in volunteers. Yet no information on the potential of endoscopic
mitochondrial oxygen measurements in diagnosing CGI in patients suspected of
CGI is available.

To determine the difference in baseline MR flow measurements and post-prandial
MR flow measurements between patients diagnosed with CGI and patients not
diagnosed with CGI. To gather information on the potential of endoscopic
mitochondrial oxygen measurements in diagnosing CGI in patients suspected of
CGI.

Prospective cohort study.

The MR flow measurements will take 1 hour to 1.5 hour during one additional
visit besides the standard work-up for CGI patients. No contrast agent or
radiation is used for the MR flow measurements. Because most patients with CGI
present with post-prandial pain, abdominal pain may occur when stimulation with
the nutritional drink starts. We will be aware of this pain and ask the patient
several times if the pain occurs and stop if necessary.
The risks of mitochondrial oxygen measurements during routine upper endoscopy
are very low, especially when no sedation is used. Oral administration of
Gliolan (for PpIX induction) has a good safety profile. The risk of mucosal
phototoxicity during upper endoscopy is considered low, since the COMET uses
short-pulsed excitation and very low total light dosage. To limit the potential
effects of phototoxicity, patients will be instructed to avoid exposure to
direct sunlight of eyes and skin for 24 hours after administration of Gliolan.