Technical
TECHNICAL NOTES
Vol. 124
517
Notes
Fig. 3. Large, pendulous, radiographically dense breast examined in the lateral view using dependant compression mammography. The arrows indicate dystrophic calcifications in biopsy scars. Adhesive tape was used to mark the skin incisions. The appearance was unchanged on fOllow-up one year later.
~
Fig. 4. A. Small, dense breast in a 24-year-old nulliparous woman. Circles set off the calcifications. B. Close-up view of the calcifications.
Orthopantomography of the Cervical Spine 1 Makoto Furuse, M.D., Kazuhiko Saito, M.D., Koji Shibuya, M.D., Taro Watanabe, M.D., Tadashi Ohsawa, M.D., and Tetsuo Saito, R.T. The authors describe the application of orthopantomography to study of the intervertebral foramina of the cervical spine in patients with cervical spondylosis. Other structures such as the lateral mass of the cervical spine can be studied by altering the speed of the rotating film holder, which in turn changes the width of the arch of the focal layer. INDEX TERMS: Spine, ankylosis; arthritis (Cervical spine, degenerative small joint disorder, 3[1].775). Spine, radiography (Cervical spine, other tomography,
3[1].1219) Radiology 124:517-520, August 1977
The intervertebral foramen of the lower cervical spine is frequently involved in cervical spondylosis. The standard oblique projection with the x-ray beam centered at C5-C6 will usually demonstrate the intervertebral foramina satisfactorily for detection of bony spurs. However, it is not always easy to visualize the entire foramina (particularly those above C4) well enough to satisfy the diagnostician. Orthopantomography (4) is a radiographic technique which affords a panoramic view of a curved surface by rotating the x-ray tube and film holder during exposure. Its conventional application to medical radiographic work-up has been limited to the study of the mandible, maxilla, and temporomandibular joint (2). We have been using orthopantomography (with minor
Fig. 2. Panoramic view of the intervertebral foramina (C2-C7) of the cervical spine. Note the small bony spur on the left C6-C7 intervertebral foramen. Fig. 3. Bony spurs encroach on both C3-C4 intervertebral foramina. Fig. 4. The lateral mass is focused on both sides. The image is magnified due to placement of the lateral mass on the wider portion of the arch.
518
TECHNICAL NOTES
Vol. 124
--;
519
Technical Notes
t-
FOCAL LAYER Fig. 1. Thecurved layerof focus of the orthopantomographic unit. Theoretically, any symmetrically situated structures can be placed on this arch. modifications) as a supplementary technique to view the intervertebral foramina when they cannot be evaluated adequately because of poor positioning, improper centering of the beam, or shadows of superimposed structures. METHOD We use a Toslayer TR-840 unit (Toshiba), which has a target-film distance of 50 cm, an effective focal spot of 1.0 X 1.0 mm, 2700 rotation, and factors of 62-70 kVp, 7 mA, and 19 sec. fixed exposure time. The patient is seated on the chair with his chin resting on the adjustable holder. His front teeth should be approximately 85 mm anterior to the recommended position for the study of teeth. His head is then slightly extended with the aid of head supports to remove the jaw from the areas of interest so that Reid's base line (from the infraorbital margin to the external auditory meatus) forms an angle of approximately 15-18° with the horizontal plane. DISCUSSION The Toslayer TR-840 is designed to use a rotating curved cassette and has three fulcrums which are effectively arranged to describe an elliptical track corresponding to the average adult dental arch (Fig. 1). Synchronized movement of the x-ray tube and film holder with continuous transition from one fulcrum to another blurs out the structures outside the focal layer, showing the wide, curved object of interest on the radiograph. The focal layer of the apparatus is 12 mm thick at the molar region and becomes gradually thinner toward the front teeth. This basic principle was applied to the view of the intervertebral foramina of the cervical spine. Anatomically, the average distance between the foramina is 30 mm, which is roughly equivalent to the premolar region of the dental arch. Approximately 85 mm behind the premolar region, the intervertebral foramina of the cervical spine are aligned vertically in a slight anterior arcuate fashion with the external auditory meatus in the coronal plane; thus the meatus should be placed in the original position of the premolar region for the intervertebral foramina to be in focus using this apparatus. This required minor modification of the unit, including freer anterior movement of the chin holder and chair. Radiographs of the intervertebral foramina taken in this way proved to be satisfactory in most patients with cervical spondylosis (Figs. 2 and 3). Luschka's joints and articular facets were delineated better and free of superimposed shadows, permitting an accurate evaluation of the integrity of the entire intervertebral foramina.
Fig. 5. A. Normalhypoglossal canals(arrows). B. Theleft hypoglossal canal is partlydestroyed inthis patientwith a hypoglossal nerve neurinoma. The arrow indicates the normal side. The quality of the radiographs using this method is largely attributable to the zonographic effect, which is one of the main features of orthopantomography. The entire structure of interest is displayed in sharp focus against a blurred background, and natural subject contrast is retained (1). Scattered radiation is almost negligible due to the narrowing of the x-ray beam by the slit (3). However, the displaced, blurred margins of articular facets or vertebral bodies not in focus may give an erroneous idea of the status of the intervertebral foramina; these "phantom shadows" are created by the still fairly distinct margin outside the focal layer. Results are almost always reproducible in those patients who are able to sit still with their chin resting on the holder for 19 seconds. Reproducibility is particularly good in patients with minor to moderate bony spurs encroaching upon the intervertebral foramina or degenerative changes of the lateral mass, and one or two attempts are sufficient for useful clinical information. In those with severe spondylosis, the cervical spine is often rotated and one side or part of the foramen is thrown out of focus, which may necessitate 3 or 4 attempts before the entire foramen can be viewed in focus; thus reproducibility is somewhat less. However, distortion of alignment will be readily noticed in one attempt. Acutely ill or injured patients are not good candidates for this procedure; indeed, the greatest difficulty we encountered was achieving correct positioning of the debilitated patient and maintaining it during the entire 19-second exposure, necessitating the use of a head support. We feel that this problem will never be entirely solved unless the unit is reconstructed so as to include a horizontal table, thus enabling one to perform the examination with the patient in a recumbent position. Basal tomography is preferable for views of the hypoglossal canal. We subsequently modified the unit for multiple purposes by adjusting the width of the arch of the focal layer, which can be
520
TECHNICAL NOTES
done by altering the speed of the rotating film holder independently of the x-ray-tube travel: the faster the rotation, the wider the arch of the focal layer. This modification made it convenient to observe other structures. For example, the lateral mass of the cervical spine is pictured easily in the same position as for intervertebral foramina by speeding up the rotation of the film holder (Fig. 4) due to its more lateral location. Work-up of patients with trauma to the lateral mass may be possible with further refinement of the unit (5); and this can be also applied to imaging of the hypoglossal canal (Fig. 5). The estimated radiation exposure dose to various portions in orthopantomography is low enough for practical use. The eyes received less than 10 mR from a single exposure in our experimental study using a thermoluminescent dosimeter. To decrease the exposure dose further, the central unwanted portion of the exposure could be interrupted (2); however, this could obscure the anatomical details of the vertebral body. In conclusion, we would say on the basis of our clinical experience that orthopantomography is best applied to outlining the lateral vertebral
August 1977
mass or intervertebral foramina in patients with cervical spondylosis. REFERENCES 1. Christensen EE, Curry TS III, Nunnally JE: An Introduction to the Physics of Diagnostic Radiology. Philadelphia, Lea and Febiger, 1972, pp 196-212 2. Greig JH, MusaphFW: A method of radiological demonstration of the temporomandibular joints using the orthopantomograph. Radiology 106:307-310, Feb 1973 3. Jaffe C, Webster EW: Radiographic contrast improvement by means of slit radiography. Radiology 116:631-635, Sep 1975 4. Paatero YV: A new tomographical method for radiographing curved outer surfaces. Acta Radiol 32: 177-184, 1949 5. Smith RG, Abel MS: Visualizationof the posterolateralelements of the upper cervical vertebrae in the anteroposterior projection. Radiology 115:219-220, Apr 1975
1 From the Department of Radiology, Jichi Medical School, Minamikawachi-Machi, Tochigi Pref., Japan 329-04. Accepted for publication in June 1976. sjh
Cervical Spine Lateral Horizontal Beam Technique 1 Richard F. Tenney, M.D., and Ernest S. Kerekes, M.D. Two techniques are suggested for satisfactory horizontal beam laterals in the operating room for fusion level localization: (a) the prone cervical myelographic lateral in which a modification is suggested for the "swimmer's" position; and (b) patient supine with a 15 X 3Q-cmrolled sheet placed under the occiput and/or midline upper dorsal spine, which enables the shoulders to drop to the table, clearing the low cervical spine. INDEX TERMS: (Cervical spine, other special projections, 3[1].1259). Myelography, technique. Spine, radiography Radiology 124:520, August 1977
Fig. 1.
Prone cervical myelographic lateral.
Previously, horizontal beam-laterals in the operating room for fusion-level localization were usually unsatisfactory in the low cervical area, as the shoulders interfere. PRONE CERVICAL MYELOGRAPHIC LATERAL This is a substitute for "swimmer's" position. When controls are set for the horizontal beam lateral, the patient is instructed to place hands palms down under each shoulder, then roll the shoulder blades together in back like a soldier at attention (Fig. 1). SUPINE CERVICAL SPINE Roll a sheet into a firm 15 X 30-cm tube, tape to prevent unravelling and place it under the occiput and/or midline upper cervical and dorsal spine. The shoulders drop to the table, clearing the low cervical area. Caudad arm traction may give further improvement. In either the emergency room or x-ray department, after sandbag head immobilization, the "roll" can be tried under the stretcher; usually, there is enough "sag" to clear both stretcher side arms, and shoulders. If not, angle the primary beam slightly
Fig. 2.
Supine cervical spine.
caudad, skipping the top of the "near" shoulder (Fig. 2).
1 From the Departments of Neurosurgery and Radiology, St. John's Hospital, 1923 South Utica Avenue, Tulsa, Okla. 74104. Accepted for shan publication in May 1976.
TECHNICAL NOTES
Vol. 124
517
Notes
Fig. 3. Large, pendulous, radiographically dense breast examined in the lateral view using dependant compression mammography. The arrows indicate dystrophic calcifications in biopsy scars. Adhesive tape was used to mark the skin incisions. The appearance was unchanged on fOllow-up one year later.
~
Fig. 4. A. Small, dense breast in a 24-year-old nulliparous woman. Circles set off the calcifications. B. Close-up view of the calcifications.
Orthopantomography of the Cervical Spine 1 Makoto Furuse, M.D., Kazuhiko Saito, M.D., Koji Shibuya, M.D., Taro Watanabe, M.D., Tadashi Ohsawa, M.D., and Tetsuo Saito, R.T. The authors describe the application of orthopantomography to study of the intervertebral foramina of the cervical spine in patients with cervical spondylosis. Other structures such as the lateral mass of the cervical spine can be studied by altering the speed of the rotating film holder, which in turn changes the width of the arch of the focal layer. INDEX TERMS: Spine, ankylosis; arthritis (Cervical spine, degenerative small joint disorder, 3[1].775). Spine, radiography (Cervical spine, other tomography,
3[1].1219) Radiology 124:517-520, August 1977
The intervertebral foramen of the lower cervical spine is frequently involved in cervical spondylosis. The standard oblique projection with the x-ray beam centered at C5-C6 will usually demonstrate the intervertebral foramina satisfactorily for detection of bony spurs. However, it is not always easy to visualize the entire foramina (particularly those above C4) well enough to satisfy the diagnostician. Orthopantomography (4) is a radiographic technique which affords a panoramic view of a curved surface by rotating the x-ray tube and film holder during exposure. Its conventional application to medical radiographic work-up has been limited to the study of the mandible, maxilla, and temporomandibular joint (2). We have been using orthopantomography (with minor
Fig. 2. Panoramic view of the intervertebral foramina (C2-C7) of the cervical spine. Note the small bony spur on the left C6-C7 intervertebral foramen. Fig. 3. Bony spurs encroach on both C3-C4 intervertebral foramina. Fig. 4. The lateral mass is focused on both sides. The image is magnified due to placement of the lateral mass on the wider portion of the arch.
518
TECHNICAL NOTES
Vol. 124
--;
519
Technical Notes
t-
FOCAL LAYER Fig. 1. Thecurved layerof focus of the orthopantomographic unit. Theoretically, any symmetrically situated structures can be placed on this arch. modifications) as a supplementary technique to view the intervertebral foramina when they cannot be evaluated adequately because of poor positioning, improper centering of the beam, or shadows of superimposed structures. METHOD We use a Toslayer TR-840 unit (Toshiba), which has a target-film distance of 50 cm, an effective focal spot of 1.0 X 1.0 mm, 2700 rotation, and factors of 62-70 kVp, 7 mA, and 19 sec. fixed exposure time. The patient is seated on the chair with his chin resting on the adjustable holder. His front teeth should be approximately 85 mm anterior to the recommended position for the study of teeth. His head is then slightly extended with the aid of head supports to remove the jaw from the areas of interest so that Reid's base line (from the infraorbital margin to the external auditory meatus) forms an angle of approximately 15-18° with the horizontal plane. DISCUSSION The Toslayer TR-840 is designed to use a rotating curved cassette and has three fulcrums which are effectively arranged to describe an elliptical track corresponding to the average adult dental arch (Fig. 1). Synchronized movement of the x-ray tube and film holder with continuous transition from one fulcrum to another blurs out the structures outside the focal layer, showing the wide, curved object of interest on the radiograph. The focal layer of the apparatus is 12 mm thick at the molar region and becomes gradually thinner toward the front teeth. This basic principle was applied to the view of the intervertebral foramina of the cervical spine. Anatomically, the average distance between the foramina is 30 mm, which is roughly equivalent to the premolar region of the dental arch. Approximately 85 mm behind the premolar region, the intervertebral foramina of the cervical spine are aligned vertically in a slight anterior arcuate fashion with the external auditory meatus in the coronal plane; thus the meatus should be placed in the original position of the premolar region for the intervertebral foramina to be in focus using this apparatus. This required minor modification of the unit, including freer anterior movement of the chin holder and chair. Radiographs of the intervertebral foramina taken in this way proved to be satisfactory in most patients with cervical spondylosis (Figs. 2 and 3). Luschka's joints and articular facets were delineated better and free of superimposed shadows, permitting an accurate evaluation of the integrity of the entire intervertebral foramina.
Fig. 5. A. Normalhypoglossal canals(arrows). B. Theleft hypoglossal canal is partlydestroyed inthis patientwith a hypoglossal nerve neurinoma. The arrow indicates the normal side. The quality of the radiographs using this method is largely attributable to the zonographic effect, which is one of the main features of orthopantomography. The entire structure of interest is displayed in sharp focus against a blurred background, and natural subject contrast is retained (1). Scattered radiation is almost negligible due to the narrowing of the x-ray beam by the slit (3). However, the displaced, blurred margins of articular facets or vertebral bodies not in focus may give an erroneous idea of the status of the intervertebral foramina; these "phantom shadows" are created by the still fairly distinct margin outside the focal layer. Results are almost always reproducible in those patients who are able to sit still with their chin resting on the holder for 19 seconds. Reproducibility is particularly good in patients with minor to moderate bony spurs encroaching upon the intervertebral foramina or degenerative changes of the lateral mass, and one or two attempts are sufficient for useful clinical information. In those with severe spondylosis, the cervical spine is often rotated and one side or part of the foramen is thrown out of focus, which may necessitate 3 or 4 attempts before the entire foramen can be viewed in focus; thus reproducibility is somewhat less. However, distortion of alignment will be readily noticed in one attempt. Acutely ill or injured patients are not good candidates for this procedure; indeed, the greatest difficulty we encountered was achieving correct positioning of the debilitated patient and maintaining it during the entire 19-second exposure, necessitating the use of a head support. We feel that this problem will never be entirely solved unless the unit is reconstructed so as to include a horizontal table, thus enabling one to perform the examination with the patient in a recumbent position. Basal tomography is preferable for views of the hypoglossal canal. We subsequently modified the unit for multiple purposes by adjusting the width of the arch of the focal layer, which can be
520
TECHNICAL NOTES
done by altering the speed of the rotating film holder independently of the x-ray-tube travel: the faster the rotation, the wider the arch of the focal layer. This modification made it convenient to observe other structures. For example, the lateral mass of the cervical spine is pictured easily in the same position as for intervertebral foramina by speeding up the rotation of the film holder (Fig. 4) due to its more lateral location. Work-up of patients with trauma to the lateral mass may be possible with further refinement of the unit (5); and this can be also applied to imaging of the hypoglossal canal (Fig. 5). The estimated radiation exposure dose to various portions in orthopantomography is low enough for practical use. The eyes received less than 10 mR from a single exposure in our experimental study using a thermoluminescent dosimeter. To decrease the exposure dose further, the central unwanted portion of the exposure could be interrupted (2); however, this could obscure the anatomical details of the vertebral body. In conclusion, we would say on the basis of our clinical experience that orthopantomography is best applied to outlining the lateral vertebral
August 1977
mass or intervertebral foramina in patients with cervical spondylosis. REFERENCES 1. Christensen EE, Curry TS III, Nunnally JE: An Introduction to the Physics of Diagnostic Radiology. Philadelphia, Lea and Febiger, 1972, pp 196-212 2. Greig JH, MusaphFW: A method of radiological demonstration of the temporomandibular joints using the orthopantomograph. Radiology 106:307-310, Feb 1973 3. Jaffe C, Webster EW: Radiographic contrast improvement by means of slit radiography. Radiology 116:631-635, Sep 1975 4. Paatero YV: A new tomographical method for radiographing curved outer surfaces. Acta Radiol 32: 177-184, 1949 5. Smith RG, Abel MS: Visualizationof the posterolateralelements of the upper cervical vertebrae in the anteroposterior projection. Radiology 115:219-220, Apr 1975
1 From the Department of Radiology, Jichi Medical School, Minamikawachi-Machi, Tochigi Pref., Japan 329-04. Accepted for publication in June 1976. sjh
Cervical Spine Lateral Horizontal Beam Technique 1 Richard F. Tenney, M.D., and Ernest S. Kerekes, M.D. Two techniques are suggested for satisfactory horizontal beam laterals in the operating room for fusion level localization: (a) the prone cervical myelographic lateral in which a modification is suggested for the "swimmer's" position; and (b) patient supine with a 15 X 3Q-cmrolled sheet placed under the occiput and/or midline upper dorsal spine, which enables the shoulders to drop to the table, clearing the low cervical spine. INDEX TERMS: (Cervical spine, other special projections, 3[1].1259). Myelography, technique. Spine, radiography Radiology 124:520, August 1977
Fig. 1.
Prone cervical myelographic lateral.
Previously, horizontal beam-laterals in the operating room for fusion-level localization were usually unsatisfactory in the low cervical area, as the shoulders interfere. PRONE CERVICAL MYELOGRAPHIC LATERAL This is a substitute for "swimmer's" position. When controls are set for the horizontal beam lateral, the patient is instructed to place hands palms down under each shoulder, then roll the shoulder blades together in back like a soldier at attention (Fig. 1). SUPINE CERVICAL SPINE Roll a sheet into a firm 15 X 30-cm tube, tape to prevent unravelling and place it under the occiput and/or midline upper cervical and dorsal spine. The shoulders drop to the table, clearing the low cervical area. Caudad arm traction may give further improvement. In either the emergency room or x-ray department, after sandbag head immobilization, the "roll" can be tried under the stretcher; usually, there is enough "sag" to clear both stretcher side arms, and shoulders. If not, angle the primary beam slightly
Fig. 2.
Supine cervical spine.
caudad, skipping the top of the "near" shoulder (Fig. 2).
1 From the Departments of Neurosurgery and Radiology, St. John's Hospital, 1923 South Utica Avenue, Tulsa, Okla. 74104. Accepted for shan publication in May 1976.
