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ASSESSMENT OF LOCATION OF THE CELIAC AND CRANIAL
MESENTERIC ARTERIES RELATIVE TO THE THORACOLUMBAR SPINE
USING MAGNETIC RESONANCE IMAGING
RUTH DENNIS
Exact localization of thoracolumbar lesions can be harder with magnetic resonance (MR) imaging than with
radiography. The celiac and cranial mesenteric arteries are easily seen on MR images and are always included
in sagittal thoracolumbar studies. This study was undertaken to establish whether their location was sufficiently
consistent to enable them to be used as anatomic landmarks. It was found that their location varied consid-
erably, and there was no useful relationship to breed, gender, age, or body weight. They are therefore unreliable
for use in establishing initial localization of a spinal lesion although they can be helpful when comparing multiple
image planes. Veterinary Radiology & Ultrasound, Vol. 46, No. 5, 2005, pp 388–390.
Key words: celiac/cranial mesenteric artery, MRI, spine.
Introduction
MAGNETIC RESONANCE (MR) IMAGING is widely used for
spinal imaging in small animals. However, the
tomographic nature of MR imaging can cause problems
in interpretation as anatomic features that are helpful
landmarks may be excluded from the images, especially
when a small field of view is used. For example, when
imaging the spine, localizing specific vertebrae or disk
spaces requires identification of bony landmarks such as
the ribs and sacrum. This is especially important if surgery
is to be performed. Precise localization of spinal lesions is
harder using MR imaging, especially if a dorsal plane scan
(in which ribs are visible) is not performed. The anticlinal
vertebra (usually T11) may be used as a landmark but is
not always included in the imaging field of view or may not
be clearly seen.
The celiac and cranial mesenteric arteries are always
visible in sagittal MR images of the thoracolumbar area,
and the celiac artery lies close to the first lumbar vertebra.1
These vessels may also be identified in dorsal and trans-
verse images, provided they are within the field of view
(Fig. 1A–C). The purpose of this study was to document
the consistency of these two arteries relative to the spine to
establish whether they could provide a useful landmark for
identifying specific vertebrae.
Materials and Methods
The location of the celiac and cranial mesenteric arteries
relative to vertebrae and disk spaces were recorded for 100
consecutive small animal thoracolumbar MR studies. Cats
and purebreed dogs were considered. Patients with tho-
racolumbar or lumbosacral transitional vertebrae were
excluded, and only animals with seven normal lumbar ver-
tebrae were included in this study. Assessment of spinal
conformation was made from dorsal plane images, and the
thoracolumbar and lumbosacral junctions were always in-
cluded in this plane to allow the ribs to be seen and the
lumbar vertebrae to be counted.
The MR scanner used was a 1.5T GE Signa system.�
Slice thickness was generally about 3mm. The scanning
protocols always included dorsal, sagittal, and transverse
planes.
For each patient, the following data were recorded:
breed, gender, age, bodyweight, and precise location of the
two blood vessels relative to the spine. The position of
the arteries was recorded as one of 10 possible locations as
follows (celiac artery—CeA and cranial mesenteric artery
—CMA):
1. CeA¼mid T13 vertebra and CMA¼T13-L1 diskspace;
2. CeA¼ caudal T13 and CMA¼ cranial L1;3. CeA¼T13-L1 disk space and CMA¼mid L1 verte-
bra;4. both arteries ventral to L1 vertebra;5. CeA¼mid L1 vertebra and CMA¼L1-2 disk space;6. CeA – caudal L1 vertebra and CMA¼ cranial L2
vertebra;
Address correspondence and reprint requests to Ruth Dennis at theabove address. E-mail: ruth.dennis@aht.org.uk
Received December 30, 2004; accepted for publication February 23,2005.
doi: 10.1111/j.1740-8261.2005.00070.x
From the Centre for Small Animal Studies, Animal Health Trust, Lan-wades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK.
�GE Signa System, Milwaukee, WI.
388
7. CeA¼L1-2 disk space and CMA¼mid L2 vertebra;8. both arteries ventral to L2 vertebra;9. CeA¼mid L2 vertebra and CMA¼L2-3 disk space;
10. CeA¼ caudal L2 vertebra and CMA¼ cranial L3vertebra.
Results
There were 95 dogs and five cats. The 95 dogs included
20 German shepherd dogs, 11 miniature dachshunds, 10
Cavalier King Charles spaniels, six Labrador retrievers,
and five Jack Russell terriers; 27 other purebreeds were
represented by between one and four individuals. The five
cats included one Russian blue, one Burmese, one Persian,
and three domestic shorthairs. There were 53 males (31
neutered and 22 intact) and 47 females (37 neutered and 10
intact). Age ranged from 3 months to 13 years; five dogs
and one cat were juvenile. Body weight varied from 1.5 to
86kg.
The two vessels were always clearly seen and abdominal
movement artefact was never a problem. When included in
more than one MR series on a given patient, as was typical,
their location did not vary noticeably. The vessels always
arose from the ventral aspect of the abdominal aorta but
their relationship to each other was inconsistent. For ex-
ample, they could be very close to each other at their origin
or slightly further apart, they could extend cranioventrally,
ventrally or caudoventrally, and they could either run par-
allel to each other or diverge. Subjectively, their size rel-
ative to each other and to other anatomic structures was
fairly consistent. In one cat, a single large blood vessel
arose from the aorta and divided into two branches ap-
proximately 1 cm distally.
The anatomic location of the celiac artery is shown in
Fig. 2. Seventy-one percent arose ventral to L1 with 23%
more cranially located and 6% more caudal. In 97% an-
imals the cranial mesenteric artery arose ventral to L1 or
L2 as previously described.1 Two arose more cranially
(both miniature short-haired dachshunds) and one more
caudally (a 3-month-old Bulldog puppy). With regard to
breed distribution there was no consistency of location.
For example, in the largest group, German shepherd dogs,
positions 3–7 as described above were all represented. Sim-
ilarly, when location with respect to body weight was con-
sidered, no trend was detected. However, it is interesting to
note that six of the eight most cranially located vessels were
in Dachshunds and two of the three most caudal vessels
were in Bulldogs. A wide range of vessel locations (posi-
tions 4–8) were seen in the five cats. Gender and age
seemed to have no relationship to the location in either
dogs or cats.
Fig. 1. Normal appearance of the celiac and cranial mesenteric arteries:(A) longitudinally in the sagittal plane, slightly to the left of the mid-line; (B)in cross-section in the dorsal plane; and (C) the cranial mesenteric artery seenlongitudinally in a plane transverse to the spine. All images were obtainedwith T2 weighting (TR¼ 3000–4000ms and TE¼ 85ms).
389Assessment of Location ofThoracolumbar Spine Using MRIVol. 46, No. 5
Discussion
It was disappointing that there was a variable location of
the celiac and cranial mesenteric arteries with no reliable
relationship to breed or other patient factors. Clearly, these
vessels cannot be used as accurate anatomic landmarks for
identifying specific vertebrae. Nevertheless, once their po-
sition relative to the spine has been ascertained on initial
scan sequences they are helpful in deciding which vertebrae
are visible in other fields of view; for example in a more
cranially located sagittal image. Although other landmarks
such as dorsal spinous processes and areas of spondylosis
can be used, the celiac and cranial mesenteric arteries pro-
vide a conspicuous and reliable reference point. If a dorsal
plane scan extends ventral to the spine to include the or-
igins of these vessels, then not only can the ribs be iden-
tified (including asymmetric ribs on transitional vertebrae)
but the position of the vessels relative to the spine can also
be ascertained. This information can then be used when
interpreting sagittal images. This technique can be used
even when the magnet software will not allow direct cross-
referencing of slice placement between different scan
planes, and avoids the need to perform supplementary ra-
diography as is currently carried out in some clinics.
REFERENCES
1. Evans HE. The heart and arteries. In: Evans HE (ed): Miller’s anat-omy of the dog, 3rd ed. Philadelphia: Saunders, 1993;651–657.
No
. of
Cas
es (
%)
0
10
20
30
40
1 2 3 4 5 6 7 8 9 10Position
T13 L1 L2
2% 6%
15%
31%
20% 20%
3% 2% 1%
Fig. 2. Schematic representation of the location of the celiac artery rel-ative to vertebrae and disk spaces.
390 Dennis 2005