American Journal of Neuroradiology 25:1597-1598, October 2004
© 2004 American Society of Neuroradiology
Case Report
SPINE
Unilateral Transpedicular Course of an Ascending Lumbar Vein through a Pedicular Foramen Mimicking a Lytic Lesion: An Anatomic Variant
Musturay Karcaaltincabaa and
Deniz Akataa
a From the Department of Radiology, Hacettepe University School of Medicine, Ankara, Turkey
Address correspondence to Musturay Karcaaltincaba, MD, Department of Radiology, Hacettepe University School of Medicine, Sihhiye Ankara 06100, Turkey
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Abstract
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Summary: An ascending lumbar vein passing through a foramen
on the right pedicle of the third lumbar vertebra unilaterally,
which was diagnosed incidentally during virtual CT colonoscopy
of a patient with a rectal tumor, is described. Recognition
of this anatomic variation is important to avoid diagnostic
misinterpretations and transpedicular interventions such as
percutaneous vertebroplasty or surgical instrumentation that
may result in excessive hemorrhage and inadvertent leak of cement
when it is present.
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Introduction
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The ascending lumbar vein is normally located between the psoas
major and roots of the lumbar transverse processes (
1). We describe
the course of a right ascending lumbar vein through a unilateral
foramen located on the right pedicle of the third lumbar vertebra
(L3). This anatomic variation may have important clinical implications.
We could not find a similar anatomic variant through an extensive
literature search (
2–
9).
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Case Report
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A 46-year-old man presented with hematozhezia and was found
to have a rectal tumor on rectal examination. He subsequently
underwent virtual CT colonoscopy to define the extent and search
for coexisting colonic lesions and metastases. Virtual CT colonoscopy
was obtained by a four-channel multidetector CT scanner (Siemens
volume zoom, Siemens Medical Systems, Munich, Germany) by using
3-mm section thickness and a 15-mm reconstruction index after
insufflation of rectal air and intravenous contrast medium administration.
A lytic lesion with sclerotic margin on the right pedicle of
L3 was noted on axial CT scans (
Fig 1A). Upon evaluation of
sequential scans, the presence of a foramen mimicking a lytic
lesion was recognized, and a right lumbar vein was passing through
this pedicular foramen with a paravertebral course at other
lumbar levels. It is interesting to note that the left lumbar
vein had a normal anatomic course between the psoas major and
the lumbar vertebrae. We reconstructed sagittal and coronal
images and 3D volume-rendered images from axial scans (
Fig 1B–D)
at a distant workstation (Leonardo, Siemens Medical Systems).
The transpedicular course of the right ascending lumbar vein
was visible on multiplanar reformatted scans; however, it was
less well appreciated on these scans compared with axial scans
and volume-rendered scans (
Fig 1). Axial and coronal volume-rendered
scans confirmed the presence of the foramen containing an ascending
lumbar vein (
Fig 1C and D).
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FIG 1. CT findings of ascending lumbar vein passing through a lumbar (L3) pedicular foramen.
A, Axial CT scan shows a foramen (long arrow) in the right pedicle of the L3 vertebra containing the right ascending lumbar vein (short arrow). Note paravertebral course of left ascending lumbar vein (arrowhead).
B, Coronal reformatted scan shows passage of right ascending lumbar vein (short arrow) through the pedicular foramen (long arrow).
C and D, Axial and coronal volume-rendered scans show anatomic location of pedicular foramen (long arrow) and its relation to ascending lumbar vein (short arrow) to a better extent.
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Discussion
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Ascending lumbar veins normally course in a paravertebral location
between lumbar vertebrae and psoas muscle on each side. Superiorly
they usually join the subcostal vein and, passing deep to the
diaphragmatic crus, ascend as the azygos vein on the right and
as the hemiazygos on the left (
1). The ascending lumbar vein
is considered a derivative of a precostal or lumbocostal venous
system located between the vetrebrocostal element and supracardinal
vein during embryologic development (
1). In this report, we
describe the unilateral course of an ascending lumbar vein through
a pedicular foramen of L3 with a normal paravertebral course
at other lumbar vertebrae levels. The contralateral lumbar vein
had a normal course. We considered this finding as an anatomic
variation of pedicle morphologic features.
Although this anatomic variant was recognized on axial CT scans, it would be difficult to detect this foramen on direct roentgenograms or on fluoroscopic images. Moreover, it might be diagnosed as a lesion on the basis of unenhanced CT and MR imaging findings, especially during evaluation of nonsequential images obtained for studies of lumbar disks. Our patient had a rectal tumor, and this lesion might have been interpreted as a suspect lesion for bone metastasis.
With the recent increase in use of transpedicular approach by interventional radiologists for percutaneous vertebroplasty (10), anatomic and morphologic features of vertebrae pedicles gain importance in preoperative evaluation. Insertion of a needle through a pedicle containing an ascending lumbar vein might result in excessive hemorrhage and cement leak and may end up with massive pulmonary thromboembolism. Therefore, preoperative CT scanning for fluoroscopically guided procedures or CT-guided procedures can be performed, which have already been used routinely at some centers.
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Conclusion
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Transpedicular course of an ascending lumbar vein can occur
and should be known by radiologists and surgeons to avoid diagnostic
misinterpretations and potential complications that may arise
during or after transpedicular interventions.
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References
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Received January 2, 2004;
accepted after revision January 29, 2004.
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Abstract
Introduction