- Email: [email protected]
Magnetic resonance imaging of the temporomandibular joint. Part III: Use of a cephalostat for clinical imaging
CRANIOMANDIBULAR SECTION
FUNCTION
AND DYSFUNCTION
EDITOR
GEORGE A. ZARB
Magnetic resonance imaging of the temporomandibular joint. Part III: Use of a cephalostat clinical imaging K. A. Laurell, D.D.S., M.S.,* R. Tootle, D.D.S.,** J. Beltran, M.D.,**** and D. Simon, M.D.***** Ohio State University,
College of Dentistry
and College of Medicine,
S
everal problems are encountered in performing clinical magnetic resonance imaging (MRI) procedures of the temporomandibular joint (TM J). These problems include: 1. Motion artifact. Movement by the patient during the procedure causes degradation of the image.’ Procedure times can range from 1 minute to 10 minutes and the patient must remain motionless. 2. Standardization of the image plane. Previous studies have used the midsagittal plane or the skin surface over the TM J as a reference for patient orientation during the MRI procedures.‘-4 The large variation of condylar long axis angulation between individuals precludes a standardized view of the condyle when these techniques are Iused.; 3. Reproducibility. Previous studies have not indexed the pos,ition of the patient during MRI procedures.le4This omission makes exact repositioning of the patient for subsequent follow-up procedures difficult. Superimposition of images made at different times by using a reproducible technique could be useful for detecting subtle changes in morphology and positional relationships. 4. Procedure duration. MRI procedures are costly because of the high cost of the MRI device, special facilities, and trained personnel. Because patient cost is computed on a time per procedure basis, reducing procedure time is desirable. This can be done by reducing image acquisition time (at the expense of image quality) or by more efficient patient orientation procedures. Most aut:hors’-4 recommend the use of a surface Presented at the Carl 0. Boucher Prosthodontic Conference, Columbus, Ohio. Supported by The Ohio State University College of Dentistry and The Ohio State University Magnetic Resonance Council. Conducted in partial fulfillment of the requirements of the degree of Master of Science, Department of Prosthodontics, The Ohio State University. *Instructor of Restorative Dentistry, College of Dentistry. **Assistant Professc’r of Restorative Dentistry, College of Dentistry. ***Graduate student, Department of Prosthodontics, College of Dentistry. ****Assistant Profe:;sor of Radiology, College of Medicine. *****Clinical Instructor of Radiology, College of Medicine. THE JOURNAL
OF PROSTHETIC
DENTISTRY
R. Cunningham, Columbus,
for
D.D.S.*** Ohio
coil to improve signal-to-noise ratio, thereby improving the spatial and contrast resolution of the MR image. Placement of the surface coil is difficult because it must be centered exactly over the joint and should not touch the skin surface. Time used for proper patient orientation and surface coil placement can often exceed image acquisition time. To solve these problems in making MR images, a cephalostat was designed, constructed of nonferromagnetic materials, and tested during clinical imaging procedures. METHOD Thirty-five patients, 17 to 64 years of age, with clinical signs and symptoms of TMJ disordeis were enrolled as test subjects. A total of 52 TMJs were examined. All MRI procedures were performed on a 1.5 T Signa unit (General Electric Co., Schenectady, N.Y.) using a 3-inch (7.62 mm) surface coil. The MRI cephalostat (Fig. 1) (Page Design & Mfg Co., Columbus, Ohio) used during the study consisted of a platform capable of tilting 30 degrees on its base in a medial or lateral direction. Lateral uprights were fitted with adjustable ear rods for patient immobilization and orientation indexing. A nasion relator was attached to one upright for use as a third reference point. All adjustments on the device contained indices allowing a reproducible orientation. Twenty-one TMJs were imaged without the use of a cephalostat. The midsagittal planes of the subjects were oriented parallel to the sagittal image plane. Two TM Js from this group had follow-up images made by use of the described procedures, and two had follow-up images made with the use of the cephalostat to orient the condylar long axis perpendicular to the sagittal imaging plane. In addition to the previously described procedures, 31 TM Js were imaged using the cephalostat. During these procedures an axial image was made by using a partial saturation pulse sequence (TE 20 msec, TR600 msec, 128 X 256 matrix). This image was used to determine the condylar long axis and to localize the condyle 355
LAURELL
ET AL
Fig. 1. a, MRI cephalostat seen from an inferior aspect. Note tripod effect of ear rods and nasion relator to stabilize skull position. b, MRI cephalostat tilted 15 degrees toward imaging plane. Long axis of left condyle is parallel to base of cephalostat. c, View from anterior aspect showing nasion relator. d, View from lateral aspect showing 3-inch
surface coil centered over TMJ.
mediolaterally (Fig. 2). The cephalostat was adjusted to align the condylar long axis perpendicular to the sagittal image plane before making sagittal images. Two patients from this group had follow-up images made with the use of the cephalostat to reposition the head. The images resulting from these procedures were grouped according to technique and were examined for evidence of motion artifact, shape of the condyle, reproducibility (when follow-up images were available), pro: cedure duration, image quality, and amount of diagnostic information available. The results of the differing groups were compared to determine whether the images made with the use of the cephalostat differed from those made without it.
RESULTS Motidn artifact Motion artifact was identifiable in 15% (8 of 52) of the studies performed (Fig. 3). Twenty-nine percent (6 of 21) of the studies performed without the cephalostat and 6% (2 of 31) of the studies done with the cephalostat were in this category.
Standardization
of view
Outlines of the condyle demonstrated greater variation in shape beiween individuals imaged perpendicular to the midsagittal plane compared with those imaged perpendicular to the condylar long axis. Images of the condyles of the first group were consistently wider 356
anteroposteriorly (mean of 10.4 mm, range of 6.7 mm to 16.6 mm, SD 2.8) than images of condyles of the second category (mean of 6.1 mm, range of 3.5 mm to 8 mm, SD 1.2) and were more varied in appearance (Fig. 4). The image made from one procedure performed parallel to the midsagittal plane failed to depict identifiable condyle or disk. A subsequent axial localizer image of that patient revealed a condyle with 60 degrees condylar long axis to a line transecting the centers of the external
auditory meati. Imaging performed perpendicular to this long axis showed an identifiable condyle and disk.
Reproducibility A total of six TMJs had two imaging procedures performed on differing dates. Time intervals between the initial studies and the follow-up studies varied from 5 days to 6 months. The images from the two studies in which the cephalostat was used for both the initial and the follow-up procedures were found to be reproducible; that is, the outlines of the cortical bone of the fossa and
articular eminence superimposed clearly for images of the same TM J made at the separate dates (Fig. 5). This was not found for images made when the cephalostat was not used for both procedures.
Duration of procedure The mean procedure time for making bilateral MIU TMJ images in the open- and closed-mouth positions was 91 minutes
(ranging SEPTEMBER
from 1987
75 min to 105 min, VOLUME
58
NUMBER
3
MAGNETIC
RESONANCE
IMAGING
OF TMJ. PART
III
Fig. 2. Axial Iocalizer image of condyle (C) located anterior to external auditory meatus (EAM). A horizontal line passes through condylar long axis indicating correct perpendicular to this horizontal plane.
SD = 12 min) when the cephalostat was not used. The mean time for the same procedures using a cephalostat was 55 minutes (ranging from 30 min to 105 min, SD = 17 min). DISCUSSION MRIs are similar to conventional tomograms and computed tomograms (CT) in that the image visualizes the tissue in a plane at a predetermined depth of cut. The advantages of using a cephalostat while imaging the TMJ with these two radiographic modalities have been documented.6-9 The reduction of motion artifact resulting from use of the cephalostat confirmed expectations. The tripod contact of the ear rods and the nasion relator had a stabilizing effect on the head during the procedure. However, the system did not totally eliminate motion artifact because a rigid tightening of the ear rods can cause discomfort. over the time of the procedure. Instead, the cephalostat acts as a support and guide, necessary because some patients fall asleep during the procedure, allowing relaxation of the muscles that maintain the head position. A cephalostat developed for positioning and immobilizing the head during CT procedures of the TMJ has produced similar results.9 The usefulness of standardizing the image plane perpendicular to the condylar long axis when making TM J tomograms was demonstrated by Yale.5 It has also been reported th.at a 5-degree change in the angulation of the image plane could result in changes significant enough to result in a change in diagnoses made from conventional TM J radiographs.” Many authors have reported wide variations in the condylar long axis among individuals in the populations studied.“-I5 Because of THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 3. a, Motion artifact caused by patient movement during imaging procedure. b, Image of same TMJ made without motion artifact
these variations, imaging of the TM J in a plane parallel to the midsagittal plane will result in an oblique view of the condyle ranging from 0 degrees to 30 degrees. At the time of this study, most clinical MRI devices do not have the capacity to image in oblique planes. To obtain a sagittal image perpendicular to the condylar long axis, the head must be rotated until the condylar long axis is parallel to the floor. This procedure is accomplished by making an axial localizer image of the TMJ to determine the angulation of the condylar long axis. Setting the base of the cephalostat to this angle automatically aligns the condylar long axis perpendicular to the sagittal image plane, allowing the standardized image to be made. Cephalostats have been successfully used to produce superimposable TM J radiographs made on different days.6,‘6 This capability has been useful for studying long-term changes due to growth or pathosis. Recent advances in subtractive radiographic techniques are 357
LAURELL
ET AL
Fig. 4. a, Image of TMJ made with sagittal image plane parallel to patient’s midsagittal plane. Note shallow appearance of mandibular fossa, apparent absence of an articular disk, and apparent anteroposterior widening of condyle. b, Image of same TMJ made with condylar long axis perpendicular to sagittal imaging plane. Note steepness of articular eminence, anteriorly displaced disk CD), and normal appearance of outline of condyle. Condylar long axis was 45 degrees.
highly dependent on the reproducibility of the orientation of the patient during the procedures.17,18Although the number of subjects with multiple imaging procedures included in this study is small, these preliminary findings suggest that the use of a cephalostat during the MRI procedure can produce images with superimposable reproducibility. The reduction of procedure time when using the cephalostat resulted from decreased patient setup time, and the decrease in the number of procedures repeated because of patient motion. Imaging without the cephalostat required stabilizing the head with foam rubber padding and adhesive tape, and resulted in greater
Fig. 5. a, Image of TMJ made with mouth closed. Note disk (D) displaced anterior to condyle (C). b, Image of same TMJ made 5 days later. Mouth has been opened just past point where an audible click has occurred. Note that disk (D) is now between condyle (C) and articular eminence (AE). c, Superimposition of image a onto image b shows close alignment of bony structures of skull. Amount of translation needed to produce disk reduction is clearly apparent. SEPTEMBER
1987
VOLUME
58
NUMBER
3
MAGNETIC
freedom of movement for the patient. The reduction of procedure time resulted in significant cost savings to the patient. CONCLUSIONS
8.
A cephalostat can be useful for reducing motion artifact during MRI procedures of the TMJ. Standardization of the imaging plane perpendicular to the condylar long axis can be facilitated with a cephalostat and results in a more consistent view of the condyle. A cephalostat may be useful in making MRI images of the TMJ on different dates with superimposable reproducibility. A cephalostat can reduce procedure time for MRI TMJ procedures resulting in decreased costs to the patient.
2.
3.
4.
5.
6.
Harmes SE, Wilk RM, Wolford LM, Chiles DG, Milam SB. The temporomandibular joint: magnetic resonance imaging using surface coils. Radiology 1985;157:133-6. Roberts D, Schenck J, Joseph P, Foster T, Hart H, Pettigrew J, Kundel HL, Edelstein W, Haber B. Temporomandibular joint: magnetic resonance imaging. Radiology 1985;155:829-30. Katzberg RW, Schenck J, Roberts D, Tallents R, Manzione JV, Hart H, Foster T, Wayne WS, Bessette RW. Magnetic resonance imaging of the temporomandibular joint meniscus. Oral Surg 1985;59:332-5. Chiles DG, Wilk RM, Harms SE. Magnetic resonance imaging in the diagnosis of temporomandibular disorders with a report of two cases. J Craniomand Pratt 1986;4:307-12. Yale SH, Rosenberg HM, Ceballos M, Hauptfueher JD, Laminographic cephalometry in the analysis of mandibular condyle morphology. Oral Surg 1961;14:793-805. White TC, Campbell J, Anderson H. An investigation into
THE JOURNAL
OF PROSTHETIC
9. 10. 11. 12.
13.
14. 15.
REFERENCES 1.
7.
DENTISTRY
16.
17.
18.
RESONANCE
IMAGING
OF TMJ. PART
III
temporomandibular joint dysfunction. Dental record 1952;72:4957. Kurz CS. A practical method for producing roentgenograms for diagnosis and treatment of temporomandibular lesions. Illinois Dent J 1943;12:446-50. Rosenberg HM. Laminography: methods and application in oral diagnosis. J Am Dent Assoc 1967;74:88-96. Simon DC, Hess ML, Smilack MS, Beltran J. Direct sagittal CT of the temporomandibular joint. Radiology 1985;157:545. Eckerdal 0, Lundberg M. Periodic roentgenography of the temporomandibular joint. Dentomaxillofac Radio1 1975;4:4-11. Yale SH. Radiographic evaluation of the temporomandibular joint. J Am Dent Assoc 1969;79:102-7. Beckwith PF, Monfort DR, Williams BH. Accurate depth of cut in temporomandibular joint laminographs. Angle Arthod 1980; 50: 16-22. Williamson EH, Wilson CW. Use of a submental-vertex analysis of producing quality temporomandibular joint radiographs. Am J Orthodont 1976;70:200-7. Updegrave WM. Temporomandibular articulation: x-ray examination. Dent Radiogr Photogr 1953;26:41-6. Laurel1 KA, Whitacre J, Stieg M. A comparison of various angles of the mandible with the condylar long axis. J PROSTHET DENT (In press) Blaschke DD, Blaschke’TJ. A method for quantitatively determining tempormandibular joint bony relationships. J Dent Res 1981;60:35-43. Duckworth JE, Judy PF, Goodson JM, Socransky SS. A method for the geometric and densitometric standardization of intraoral radiographs. J Periodontol 1983;54:435-40. Webber RL, Ruttiman UE, Davis A. Computer-aided interpretation of radiographic changes in substraction radiography [Abstract]. J Dent Res 1982;61:278.
Reprint requeststo: DR. KIM A. LAURELL OHIO STATE UNIVERSITY COLLEGE OF DENTISTRY
COLUMBUS,OH 43210-1241
359
FUNCTION
AND DYSFUNCTION
EDITOR
GEORGE A. ZARB
Magnetic resonance imaging of the temporomandibular joint. Part III: Use of a cephalostat clinical imaging K. A. Laurell, D.D.S., M.S.,* R. Tootle, D.D.S.,** J. Beltran, M.D.,**** and D. Simon, M.D.***** Ohio State University,
College of Dentistry
and College of Medicine,
S
everal problems are encountered in performing clinical magnetic resonance imaging (MRI) procedures of the temporomandibular joint (TM J). These problems include: 1. Motion artifact. Movement by the patient during the procedure causes degradation of the image.’ Procedure times can range from 1 minute to 10 minutes and the patient must remain motionless. 2. Standardization of the image plane. Previous studies have used the midsagittal plane or the skin surface over the TM J as a reference for patient orientation during the MRI procedures.‘-4 The large variation of condylar long axis angulation between individuals precludes a standardized view of the condyle when these techniques are Iused.; 3. Reproducibility. Previous studies have not indexed the pos,ition of the patient during MRI procedures.le4This omission makes exact repositioning of the patient for subsequent follow-up procedures difficult. Superimposition of images made at different times by using a reproducible technique could be useful for detecting subtle changes in morphology and positional relationships. 4. Procedure duration. MRI procedures are costly because of the high cost of the MRI device, special facilities, and trained personnel. Because patient cost is computed on a time per procedure basis, reducing procedure time is desirable. This can be done by reducing image acquisition time (at the expense of image quality) or by more efficient patient orientation procedures. Most aut:hors’-4 recommend the use of a surface Presented at the Carl 0. Boucher Prosthodontic Conference, Columbus, Ohio. Supported by The Ohio State University College of Dentistry and The Ohio State University Magnetic Resonance Council. Conducted in partial fulfillment of the requirements of the degree of Master of Science, Department of Prosthodontics, The Ohio State University. *Instructor of Restorative Dentistry, College of Dentistry. **Assistant Professc’r of Restorative Dentistry, College of Dentistry. ***Graduate student, Department of Prosthodontics, College of Dentistry. ****Assistant Profe:;sor of Radiology, College of Medicine. *****Clinical Instructor of Radiology, College of Medicine. THE JOURNAL
OF PROSTHETIC
DENTISTRY
R. Cunningham, Columbus,
for
D.D.S.*** Ohio
coil to improve signal-to-noise ratio, thereby improving the spatial and contrast resolution of the MR image. Placement of the surface coil is difficult because it must be centered exactly over the joint and should not touch the skin surface. Time used for proper patient orientation and surface coil placement can often exceed image acquisition time. To solve these problems in making MR images, a cephalostat was designed, constructed of nonferromagnetic materials, and tested during clinical imaging procedures. METHOD Thirty-five patients, 17 to 64 years of age, with clinical signs and symptoms of TMJ disordeis were enrolled as test subjects. A total of 52 TMJs were examined. All MRI procedures were performed on a 1.5 T Signa unit (General Electric Co., Schenectady, N.Y.) using a 3-inch (7.62 mm) surface coil. The MRI cephalostat (Fig. 1) (Page Design & Mfg Co., Columbus, Ohio) used during the study consisted of a platform capable of tilting 30 degrees on its base in a medial or lateral direction. Lateral uprights were fitted with adjustable ear rods for patient immobilization and orientation indexing. A nasion relator was attached to one upright for use as a third reference point. All adjustments on the device contained indices allowing a reproducible orientation. Twenty-one TMJs were imaged without the use of a cephalostat. The midsagittal planes of the subjects were oriented parallel to the sagittal image plane. Two TM Js from this group had follow-up images made by use of the described procedures, and two had follow-up images made with the use of the cephalostat to orient the condylar long axis perpendicular to the sagittal imaging plane. In addition to the previously described procedures, 31 TM Js were imaged using the cephalostat. During these procedures an axial image was made by using a partial saturation pulse sequence (TE 20 msec, TR600 msec, 128 X 256 matrix). This image was used to determine the condylar long axis and to localize the condyle 355
LAURELL
ET AL
Fig. 1. a, MRI cephalostat seen from an inferior aspect. Note tripod effect of ear rods and nasion relator to stabilize skull position. b, MRI cephalostat tilted 15 degrees toward imaging plane. Long axis of left condyle is parallel to base of cephalostat. c, View from anterior aspect showing nasion relator. d, View from lateral aspect showing 3-inch
surface coil centered over TMJ.
mediolaterally (Fig. 2). The cephalostat was adjusted to align the condylar long axis perpendicular to the sagittal image plane before making sagittal images. Two patients from this group had follow-up images made with the use of the cephalostat to reposition the head. The images resulting from these procedures were grouped according to technique and were examined for evidence of motion artifact, shape of the condyle, reproducibility (when follow-up images were available), pro: cedure duration, image quality, and amount of diagnostic information available. The results of the differing groups were compared to determine whether the images made with the use of the cephalostat differed from those made without it.
RESULTS Motidn artifact Motion artifact was identifiable in 15% (8 of 52) of the studies performed (Fig. 3). Twenty-nine percent (6 of 21) of the studies performed without the cephalostat and 6% (2 of 31) of the studies done with the cephalostat were in this category.
Standardization
of view
Outlines of the condyle demonstrated greater variation in shape beiween individuals imaged perpendicular to the midsagittal plane compared with those imaged perpendicular to the condylar long axis. Images of the condyles of the first group were consistently wider 356
anteroposteriorly (mean of 10.4 mm, range of 6.7 mm to 16.6 mm, SD 2.8) than images of condyles of the second category (mean of 6.1 mm, range of 3.5 mm to 8 mm, SD 1.2) and were more varied in appearance (Fig. 4). The image made from one procedure performed parallel to the midsagittal plane failed to depict identifiable condyle or disk. A subsequent axial localizer image of that patient revealed a condyle with 60 degrees condylar long axis to a line transecting the centers of the external
auditory meati. Imaging performed perpendicular to this long axis showed an identifiable condyle and disk.
Reproducibility A total of six TMJs had two imaging procedures performed on differing dates. Time intervals between the initial studies and the follow-up studies varied from 5 days to 6 months. The images from the two studies in which the cephalostat was used for both the initial and the follow-up procedures were found to be reproducible; that is, the outlines of the cortical bone of the fossa and
articular eminence superimposed clearly for images of the same TM J made at the separate dates (Fig. 5). This was not found for images made when the cephalostat was not used for both procedures.
Duration of procedure The mean procedure time for making bilateral MIU TMJ images in the open- and closed-mouth positions was 91 minutes
(ranging SEPTEMBER
from 1987
75 min to 105 min, VOLUME
58
NUMBER
3
MAGNETIC
RESONANCE
IMAGING
OF TMJ. PART
III
Fig. 2. Axial Iocalizer image of condyle (C) located anterior to external auditory meatus (EAM). A horizontal line passes through condylar long axis indicating correct perpendicular to this horizontal plane.
SD = 12 min) when the cephalostat was not used. The mean time for the same procedures using a cephalostat was 55 minutes (ranging from 30 min to 105 min, SD = 17 min). DISCUSSION MRIs are similar to conventional tomograms and computed tomograms (CT) in that the image visualizes the tissue in a plane at a predetermined depth of cut. The advantages of using a cephalostat while imaging the TMJ with these two radiographic modalities have been documented.6-9 The reduction of motion artifact resulting from use of the cephalostat confirmed expectations. The tripod contact of the ear rods and the nasion relator had a stabilizing effect on the head during the procedure. However, the system did not totally eliminate motion artifact because a rigid tightening of the ear rods can cause discomfort. over the time of the procedure. Instead, the cephalostat acts as a support and guide, necessary because some patients fall asleep during the procedure, allowing relaxation of the muscles that maintain the head position. A cephalostat developed for positioning and immobilizing the head during CT procedures of the TMJ has produced similar results.9 The usefulness of standardizing the image plane perpendicular to the condylar long axis when making TM J tomograms was demonstrated by Yale.5 It has also been reported th.at a 5-degree change in the angulation of the image plane could result in changes significant enough to result in a change in diagnoses made from conventional TM J radiographs.” Many authors have reported wide variations in the condylar long axis among individuals in the populations studied.“-I5 Because of THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 3. a, Motion artifact caused by patient movement during imaging procedure. b, Image of same TMJ made without motion artifact
these variations, imaging of the TM J in a plane parallel to the midsagittal plane will result in an oblique view of the condyle ranging from 0 degrees to 30 degrees. At the time of this study, most clinical MRI devices do not have the capacity to image in oblique planes. To obtain a sagittal image perpendicular to the condylar long axis, the head must be rotated until the condylar long axis is parallel to the floor. This procedure is accomplished by making an axial localizer image of the TMJ to determine the angulation of the condylar long axis. Setting the base of the cephalostat to this angle automatically aligns the condylar long axis perpendicular to the sagittal image plane, allowing the standardized image to be made. Cephalostats have been successfully used to produce superimposable TM J radiographs made on different days.6,‘6 This capability has been useful for studying long-term changes due to growth or pathosis. Recent advances in subtractive radiographic techniques are 357
LAURELL
ET AL
Fig. 4. a, Image of TMJ made with sagittal image plane parallel to patient’s midsagittal plane. Note shallow appearance of mandibular fossa, apparent absence of an articular disk, and apparent anteroposterior widening of condyle. b, Image of same TMJ made with condylar long axis perpendicular to sagittal imaging plane. Note steepness of articular eminence, anteriorly displaced disk CD), and normal appearance of outline of condyle. Condylar long axis was 45 degrees.
highly dependent on the reproducibility of the orientation of the patient during the procedures.17,18Although the number of subjects with multiple imaging procedures included in this study is small, these preliminary findings suggest that the use of a cephalostat during the MRI procedure can produce images with superimposable reproducibility. The reduction of procedure time when using the cephalostat resulted from decreased patient setup time, and the decrease in the number of procedures repeated because of patient motion. Imaging without the cephalostat required stabilizing the head with foam rubber padding and adhesive tape, and resulted in greater
Fig. 5. a, Image of TMJ made with mouth closed. Note disk (D) displaced anterior to condyle (C). b, Image of same TMJ made 5 days later. Mouth has been opened just past point where an audible click has occurred. Note that disk (D) is now between condyle (C) and articular eminence (AE). c, Superimposition of image a onto image b shows close alignment of bony structures of skull. Amount of translation needed to produce disk reduction is clearly apparent. SEPTEMBER
1987
VOLUME
58
NUMBER
3
MAGNETIC
freedom of movement for the patient. The reduction of procedure time resulted in significant cost savings to the patient. CONCLUSIONS
8.
A cephalostat can be useful for reducing motion artifact during MRI procedures of the TMJ. Standardization of the imaging plane perpendicular to the condylar long axis can be facilitated with a cephalostat and results in a more consistent view of the condyle. A cephalostat may be useful in making MRI images of the TMJ on different dates with superimposable reproducibility. A cephalostat can reduce procedure time for MRI TMJ procedures resulting in decreased costs to the patient.
2.
3.
4.
5.
6.
Harmes SE, Wilk RM, Wolford LM, Chiles DG, Milam SB. The temporomandibular joint: magnetic resonance imaging using surface coils. Radiology 1985;157:133-6. Roberts D, Schenck J, Joseph P, Foster T, Hart H, Pettigrew J, Kundel HL, Edelstein W, Haber B. Temporomandibular joint: magnetic resonance imaging. Radiology 1985;155:829-30. Katzberg RW, Schenck J, Roberts D, Tallents R, Manzione JV, Hart H, Foster T, Wayne WS, Bessette RW. Magnetic resonance imaging of the temporomandibular joint meniscus. Oral Surg 1985;59:332-5. Chiles DG, Wilk RM, Harms SE. Magnetic resonance imaging in the diagnosis of temporomandibular disorders with a report of two cases. J Craniomand Pratt 1986;4:307-12. Yale SH, Rosenberg HM, Ceballos M, Hauptfueher JD, Laminographic cephalometry in the analysis of mandibular condyle morphology. Oral Surg 1961;14:793-805. White TC, Campbell J, Anderson H. An investigation into
THE JOURNAL
OF PROSTHETIC
9. 10. 11. 12.
13.
14. 15.
REFERENCES 1.
7.
DENTISTRY
16.
17.
18.
RESONANCE
IMAGING
OF TMJ. PART
III
temporomandibular joint dysfunction. Dental record 1952;72:4957. Kurz CS. A practical method for producing roentgenograms for diagnosis and treatment of temporomandibular lesions. Illinois Dent J 1943;12:446-50. Rosenberg HM. Laminography: methods and application in oral diagnosis. J Am Dent Assoc 1967;74:88-96. Simon DC, Hess ML, Smilack MS, Beltran J. Direct sagittal CT of the temporomandibular joint. Radiology 1985;157:545. Eckerdal 0, Lundberg M. Periodic roentgenography of the temporomandibular joint. Dentomaxillofac Radio1 1975;4:4-11. Yale SH. Radiographic evaluation of the temporomandibular joint. J Am Dent Assoc 1969;79:102-7. Beckwith PF, Monfort DR, Williams BH. Accurate depth of cut in temporomandibular joint laminographs. Angle Arthod 1980; 50: 16-22. Williamson EH, Wilson CW. Use of a submental-vertex analysis of producing quality temporomandibular joint radiographs. Am J Orthodont 1976;70:200-7. Updegrave WM. Temporomandibular articulation: x-ray examination. Dent Radiogr Photogr 1953;26:41-6. Laurel1 KA, Whitacre J, Stieg M. A comparison of various angles of the mandible with the condylar long axis. J PROSTHET DENT (In press) Blaschke DD, Blaschke’TJ. A method for quantitatively determining tempormandibular joint bony relationships. J Dent Res 1981;60:35-43. Duckworth JE, Judy PF, Goodson JM, Socransky SS. A method for the geometric and densitometric standardization of intraoral radiographs. J Periodontol 1983;54:435-40. Webber RL, Ruttiman UE, Davis A. Computer-aided interpretation of radiographic changes in substraction radiography [Abstract]. J Dent Res 1982;61:278.
Reprint requeststo: DR. KIM A. LAURELL OHIO STATE UNIVERSITY COLLEGE OF DENTISTRY
COLUMBUS,OH 43210-1241
359