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