Published online before print October 9, 2001, 10.1148/radiol.2213991129
(Radiology. 2001;221:787-788.)
© RSNA, 2001
The Intravertebral Vacuum Cleft Sign1
Daphne J. Theodorou, MD
1 From the Department of Radiology, School of Medicine, University of California, San Diego Medical Center, Calif. Received June 8, 1999; revision requested August 3; revision received February 23, 2000; accepted March 7. Supported by VA grant no. SA-360 and A. S. Onassis Public Benefit Foundation grant no. U-033. Address correspondence to the author, Department of Radiology, Veterans Affairs Medical Center, 3350 La Jolla Village Dr, San Diego, CA 92161.
Index terms: Bones, necrosis, 30.497 • Signs in Imaging • Spine, abnormalities, 30.497 • Spine, fractures, 30.41, 30.497
 |
APPEARANCE
|
|---|
The intravertebral vacuum cleft sign appears on radiographs as a transverse, linear or semilunar radiolucent shadow that is located centrally within or adjacent to the endplate of a collapsed vertebral body (Figure, part a). Although the sign is usually more conspicuously seen on frontal radiographs of the spine (1), additional lateral views may help distinguish between an intraosseous, intervertebral, or bowel location of the lucency (2). The intravertebral vacuum cleft sign may also be seen on computed tomographic (CT) images and magnetic resonance (MR) images of the thoracic and lumbar spine. On CT scans, the sign may appear more heterogeneous and irregular than it does on radiographs (3). On MR images, the sign is generally seen as low signal intensity with all sequences (Figure, parts b–d), and magnetic susceptibility effects are evident on gradient-echo images (4). At times, however, the sign may appear as high signal intensity on T2-weighted images (3).
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure a. Images in a 65-year-old woman with vertebral collapse sustained 9 months after a motor vehicle accident. (a) Lateral radiograph of the thoracolumbar spine demonstrates an intraosseous, semilunar radiolucent shadow (arrows) within the collapsed L1 vertebral body; this radiolucent shadow represents the intravertebral vacuum cleft sign. (b) Sagittal T1-weighted (repetition time msec/echo time msec, 320/12) spin-echo MR image shows abnormally low marrow signal intensity (solid arrows) in the involved L1 vertebral body. Diffuse, low signal intensity (open arrows) is even more prominent in the central portion of the vertebral body. (c) Sagittal intermediate-weighted (2,000/17) fast spin-echo MR image reveals abnormally low signal intensity (arrows) in the central portion of the collapsed L1 vertebral body that represents intravertebral gas collection. (d) Sagittal T2-weighted (3,300/102; echo train length, eight) fast spin-echo MR image again shows the collapsed vertebral body (solid arrows), which contains a central area of abnormally low signal intensity (open arrows) consistent with intravertebral gas collection.
|
|
View larger version (146K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure b. Images in a 65-year-old woman with vertebral collapse sustained 9 months after a motor vehicle accident. (a) Lateral radiograph of the thoracolumbar spine demonstrates an intraosseous, semilunar radiolucent shadow (arrows) within the collapsed L1 vertebral body; this radiolucent shadow represents the intravertebral vacuum cleft sign. (b) Sagittal T1-weighted (repetition time msec/echo time msec, 320/12) spin-echo MR image shows abnormally low marrow signal intensity (solid arrows) in the involved L1 vertebral body. Diffuse, low signal intensity (open arrows) is even more prominent in the central portion of the vertebral body. (c) Sagittal intermediate-weighted (2,000/17) fast spin-echo MR image reveals abnormally low signal intensity (arrows) in the central portion of the collapsed L1 vertebral body that represents intravertebral gas collection. (d) Sagittal T2-weighted (3,300/102; echo train length, eight) fast spin-echo MR image again shows the collapsed vertebral body (solid arrows), which contains a central area of abnormally low signal intensity (open arrows) consistent with intravertebral gas collection.
|
|
View larger version (141K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure c. Images in a 65-year-old woman with vertebral collapse sustained 9 months after a motor vehicle accident. (a) Lateral radiograph of the thoracolumbar spine demonstrates an intraosseous, semilunar radiolucent shadow (arrows) within the collapsed L1 vertebral body; this radiolucent shadow represents the intravertebral vacuum cleft sign. (b) Sagittal T1-weighted (repetition time msec/echo time msec, 320/12) spin-echo MR image shows abnormally low marrow signal intensity (solid arrows) in the involved L1 vertebral body. Diffuse, low signal intensity (open arrows) is even more prominent in the central portion of the vertebral body. (c) Sagittal intermediate-weighted (2,000/17) fast spin-echo MR image reveals abnormally low signal intensity (arrows) in the central portion of the collapsed L1 vertebral body that represents intravertebral gas collection. (d) Sagittal T2-weighted (3,300/102; echo train length, eight) fast spin-echo MR image again shows the collapsed vertebral body (solid arrows), which contains a central area of abnormally low signal intensity (open arrows) consistent with intravertebral gas collection.
|
|
View larger version (143K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure d. Images in a 65-year-old woman with vertebral collapse sustained 9 months after a motor vehicle accident. (a) Lateral radiograph of the thoracolumbar spine demonstrates an intraosseous, semilunar radiolucent shadow (arrows) within the collapsed L1 vertebral body; this radiolucent shadow represents the intravertebral vacuum cleft sign. (b) Sagittal T1-weighted (repetition time msec/echo time msec, 320/12) spin-echo MR image shows abnormally low marrow signal intensity (solid arrows) in the involved L1 vertebral body. Diffuse, low signal intensity (open arrows) is even more prominent in the central portion of the vertebral body. (c) Sagittal intermediate-weighted (2,000/17) fast spin-echo MR image reveals abnormally low signal intensity (arrows) in the central portion of the collapsed L1 vertebral body that represents intravertebral gas collection. (d) Sagittal T2-weighted (3,300/102; echo train length, eight) fast spin-echo MR image again shows the collapsed vertebral body (solid arrows), which contains a central area of abnormally low signal intensity (open arrows) consistent with intravertebral gas collection.
|
|
|
EXPLANATION
|
|---|
The radiolucent linear or semilunar shadow that is characteristic of the intravertebral vacuum cleft sign represents gas (principally nitrogen) in the fracture line of the vertebral body. The gas presumably originates from the surrounding tissues. While the pathogenesis of this process is not completely understood, the sign is most suggestive of ischemic necrosis of bone. Collapse of the vertebral body secondary to ischemic necrosis results in an overall decrease in the volume of bone with associated intraosseous cleft formation (5). Generated low pressure in these clefts allows accumulation of gas, which produces the intraosseous "vacuum" phenomenon of the vertebral collapse (1,5). Prolonged supine positioning, however, may lead to accumulation of fluid within the clefts (3).
|
DISCUSSION
|
|---|
Osteonecrosis of the vertebral body is recognized as a relatively uncommon disease (6). The incidence of the intravertebral vacuum cleft sign is not well known; however, gaseous collections originating within the collapsed vertebral body have been described in cases of osteonecrosis, particularly in elderly patients who receive corticosteroid medication (1).
Radiolucent linear shadows within the subchondral bone of the vertebral body represent fractures of necrotic bone that are reminiscent of the crescent sign seen in osteonecrosis at various sites (eg, femoral head, humeral head) (7). The intravertebral vacuum cleft sign has been seen with Kümmell disease, a delayed posttraumatic collapse of the vertebral body (1). Most commonly, vertebral collapse occurs as a consequence of vascular insult at the anterior segment of the vertebral body, which is supplied by anterior metaphyseal and peripheral arteries (8). Failure of the reparative process, in terms of inadequate revascularization of bone marrow and fracture healing, may predispose patients to ischemic necrosis of the vertebral body and may also result in subsequent vertebral collapse. Progression of vertebral collapse, however, may place the vertebral arterial supply in further risk, which may in turn lead to a vicious cycle. Several factors associated with failure of the healing process have been reported, including impairment of the vertebral blood supply and cartilaginous (Schmorl) nodes and normal stress placed on a weakened vertebra (9).
The intravertebral vacuum cleft sign is highly suggestive of, although not specific for, osteonecrosis (10). To my knowledge, the sign has not been described in association with acute vertebral fracture (1). In acute vertebral fracture, intraosseous hematoma occupies the clefts between bone fragments (5) and precludes collection of gas within the clefts. Rarely, gas within a vertebral body may occur with osteomyelitis due to gas-forming organisms (7).
Nevertheless, the pattern and distribution of the gas, in such cases, differ from those seen with vertebral osteonecrosis. Because the gas is generated under high pressure in cases of infection, small radiolucent collections are more typical. Furthermore, extension of gas from the bone to adjacent soft tissues is more characteristic of infection. The presence of gas within the vertebral body has also rarely been reported in cases of vertebral malignancy (11). Furthermore, focal gaseous collections in a vertebral body, most commonly involving the cervical spine, may lie within cartilaginous or Schmorl nodes (12). In that instance, intraosseous disk displacement may accompany vertebral collapse, leading to an intravertebral gaseous collection within the displaced disk itself. The gas seen in the displaced discal material demonstrates a branching pattern that possesses both horizontal and vertical components.
Although it is not universally associated with osteonecrosis, the intravertebral vacuum cleft sign militates against the diagnosis of infection or malignancy. Thus, in clinical practice, recognition of the intravertebral vacuum cleft sign may be of great benefit.
|
ACKNOWLEDGMENTS
|
|---|
The author is indebted to Donald Resnick, MD, for providing the case material.
|
FOOTNOTES
|
|---|
A trainee (resident or fellow) wishing to submit a manuscript for Signs in Imaging should first write to the Editor for approval of the sign to be prepared, to avoid duplicate preparation of the same sign.
|
REFERENCES
|
|---|
-
Maldague B, Noel H, Malghem J. The intravertebral vacuum cleft: a sign of ischemic vertebral collapse. Radiology 1978; 129:23-29.
-
Bhalla S, Reinus W. The linear intravertebral vacuum: a sign of benign vertebral collapse. AJR Am J Roentgenol 1998; 170:1563-1569.
-
Malghem J, Maldague B, Labaisse M. Intravertebral vacuum cleft: changes in content after supine positioning. Radiology 1993; 187:483-487.
-
Pathria M. Physical injury: spine. In: Resnick D, Niwayama G, eds. Diagnosis of bone and joint disorders. Philadelphia, Pa: Saunders, 1995; 2873.
-
Golimbu C, Firooznia H, Rafii M. The intravertebral vacuum sign. Spine 1986; 11:1040-1043.
-
Chou L, Knight R. Idiopathic avascular necrosis of a vertebral body: case report and literature review. Spine 1997; 22:1928-1932.
-
Resnick D, Niwayama G, Guera J, Vint V, Usselman J. Spinal vacuum phenomenon: anatomical study and review. Radiology 1981; 137:341-348.
-
Ratcliffe J. The arterial anatomy of the adult human lumbar vertebral body: a microarteriographic study. J Anat 1980; 131:57-79.
-
Benedek T, Nicholas J. Delayed traumatic vertebral body compression fracture. II. Pathologic fractures. Semin Arthritic Rheum 1981; 10:271-277.
-
Resnick D. Vertebral body. In: Resnick D, eds. Diagnosis of bone and joint disorders. 3rd ed. Philadelphia, Pa: Saunders, 1995; 3527-3530.
-
Kupman W, Salmonowitz E, Seidl G, Wittich G. The intravertebral vacuum phenomenon. Skeletal Radiol 1986; 15:444-447.
-
Larsen J, Smievoll A. Gas in a cervical vertebral body: a case report with CT confirmation. Eur J Radiol 1988; 8:98-99.
This article has been cited by other articles:
|
|
|
|
 
M. C. Wiggins, M. Sehizadeh, T. K. Pilgram, and L. A. Gilula
Importance of Intravertebral Fracture Clefts in Vertebroplasty Outcome
Am. J. Roentgenol.,
March 1, 2007;
188(3):
634 - 640.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
K.-Y. Ha, J.-S. Lee, K.-W. Kim, and J.-S. Chon
Percutaneous vertebroplasty for vertebral compression fractures with and without intravertebral clefts
J Bone Joint Surg Br,
May 1, 2006;
88-B(5):
629 - 633.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
Y. Mirovsky, Y. Anekstein, E. Shalmon, and A. Peer
Vacuum Clefts of the Vertebral Bodies
AJNR Am. J. Neuroradiol.,
August 1, 2005;
26(7):
1634 - 1640.
[Abstract]
[Full Text]
[PDF]
|
|
|
TOP
APPEARANCE
EXPLANATION
