Ostometry of the mandible performed using dental MR imaging

Abstract

On cross-sectional and panoramic reformatted images from axial (dental) CT scans of the mandible it may be difficult to identify the inferior alveolar neurovascular bundle (IANB) in patients lacking a clear-cut bony delimitation of the mandibular canal. Dental MR images are comparable to dental CT scans, which directly show the IANB; however, measurements of length may not be reliable owing to susceptibility artifacts and field inhomogeneities in the oral cavity. Therefore, the accuracy of length measurements on dental MR images was compared with that on dental CT scans and direct osteometry.
Dental T1-weighted MR imaging using a high-resolution turbo gradient-echo sequence and dental CT were performed in six anatomic specimens. The axial scans were reformatted as panoramic and cross-sectional reconstructions on a workstation and characteristic cross sections were obtained from all mandibles. The longest axis in the bucco-lingual and apico-basal directions, the distances from the top of the mandibular canal to the top of the alveolar ridge and from the bottom of the mandibular canal to the base of the mandible, and the diameter of the bone cortex at the alveolar ridge were measured with direct osteometry on the cross sections and compared with measurements on corresponding MR and CT reformatted images.
The correlation between direct osteometry and dental MR and CT was strong, except for the bone cortex diameter at the top of the alveolar ridge, where only a moderate correlation was found. Means of comparable length measurements were not significantly different among the three methods.
The accuracy of length measurements in the jaw bones obtained using dental MR is comparable to that of dental CT and is not significantly different from direct osteometry. Thus, dental MR is a potential alternative to CT for dental imaging.

Full text

1221
MS
AJNR Am J Neuroradiol 20:1221–1227, August 1999
Osteometry of the Mandible Performed Using
Dental MR Imaging
Christian J. O. Nas˘el, Michael Pretterklieber, Andre Gahleitner, Christian Czerny, Martin Breitenseher,
and Herwig Imhof
BACKGROUND AND PURPOSE: On cross-sectional and panoramic reformatted images
from axial (dental) CT scans of the mandible it may be difficult to identify the inferior
alveolar neurovascular bundle (IANB) in patients lacking a clear-cut bony delimitation of
the mandibular canal. Dental MR images are comparable to dental CT scans, which directly
show the IANB; however, measurements of length may not be reliable owing to susceptibility
artifacts and field inhomogeneities in the oral cavity. Therefore, the accuracy of length mea-
surements on dental MR images was compared with that on dental CT scans and direct
osteometry.
METHODS: Dental T1-weighted MR imaging using a high-resolution turbo gradient-echo
sequence and dental CT were performed in six anatomic specimens. The axial scans were
reformatted as panoramic and cross-sectional reconstructions on a workstation and character-
istic cross sections were obtained from all mandibles. The longest axis in the bucco-lingual and
apico-basal directions, the distances from the top of the mandibular canal to the top of the
alveolar ridge and from the bottom of the mandibular canal to the base of the mandible, and
the diameter of the bone cortex at the alveolar ridge were measured with direct osteometry on
the cross sections and compared with measurements on corresponding MR and CT reformatted
images.
RESULTS: The correlation between direct osteometry and dental MR and CT was strong,
except for the bone cortex diameter at the top of the alveolar ridge, where only a moderate
correlation was found. Means of comparable length measurements were not significantly dif-
ferent among the three methods.
CONCLUSION: The accuracy of length measurements in the jaw bones obtained using dental
MR is comparable to that of dental CT and is not significantly different from direct osteometry.
Thus, dental MR is a potential alternative to CT for dental imaging.
Surgical procedures near the mandibular canal re-
quire exact knowledge of the intraosseous course
of the inferior alveolar neurovascular bundle
(IANB), as the risk of injury is high in the absence
of adequate information. CT has proved useful in
the preoperative evaluation of patients undergoing
dental implantations and other surgical procedures
near the inferior alveolar canal, permitting avoid-
ance of possible injury to the IANB (1, 2). Since
the distances between the IANB and implants or
protheses are small, preoperative evaluation re-
quires precise measurements with an error of no
more than 1 mm (3, 4). Dental CT procedures with
multiplanar reconstructions provide this degree of
Received July 17, 1998; accepted after revision March 1, 1999.
From the Department of Radiology, University of Vienna
AKH, Wa¨hringergu¨rtel 18–20, A-1090 Vienna, Austria.
Address reprint requests to Christian J. O. Nas˘el, MD.
q American Society of Neuroradiology
precision, but only bone or calcified structures are
directly visible. Thus, in patients without a clear-
cut bony delimitation of the mandibular canal, lo-
cating the IANB on a single cross section is diffi-
cult, necessitating comparison with adjacent
parallel and correlated perpendicular reformatted
images (2).
Imaging of the jaw bones by using dental MR
sequences provides cross-sectional and panoramic
reformations comparable to dental CT procedures
(Fig 1). Because of the excellent soft-tissue con-
trast, the IANB is directly visible on cross-sectional
and panoramic reformations, independent of the
surrounding bone. Furthermore, spread of tumor or
alterations caused by inflammation in the jaw bones
are immediately apparent on dental MR images,
which provide significantly more presurgical infor-
mation (5, 6). Although dental MR imaging is
promising, spatial distortions on MR images may
be larger than those on CT scans, which could limit
the practical use of this technique. Therefore, the

AJNR: 20, August 19991222 NAS
˘
EL
F
IG
1.
A,
Panoramic reconstruction from an axial CT scan (ef-
fective section thickness of 1 mm) of a severely atrophic man-
dible. The cut line for this reconstruction was centered on the
mandibular canal (
arrowheads
), which is clearly depicted in
terms of well-distinguished bony delineations.
B,
Panoramic reconstruction from an axial T1-weighted (6.2/
20) MR image (318 flip angle and an effective section thickness
of 0.5 mm) of the same mandible as in
A
also directly shows the
course of the neurovascular bundle (
arrowheads
), which is char-
acterized by moderate signal intensity. Differentiation of nerves
and vessels is not possible.
F
IG
2.
A,
A cut line following the course
of the mandibular canal was drawn on the
dental (axial) CT scans with an effective
section thickness of 1 mm. The panoramic
and cross-sectional reconstructions were
calculated as sections parallel andperpen-
dicular to this line.
B,
A cut line for panoramic and cross-
sectional reconstructions on an axial T1-
weighted (6.2/20) MR image of the same
mandible as in
A
(318 flip angle and an
effective section thickness of 0.5 mm)
was drawn by following the neurovascular
bundle. Note the slight difference of the
orientation of the proposed cross sec-
tions, which are shown as small lines per-
pendicular to the cut line. Only exactly
parallel cross sections were used for
measurement.
accuracy of length measurements obtained from
dental MR images of the mandibles of six anatomic
specimens was evaluated by comparing the findings
with values obtained on dental CT scans and by
direct osteometry.
Methods
Six fresh-frozen anatomic specimens were examined with
dental MR imaging and dental CT, followed by anatomic dis-
section of the mandibles. Prior to scanning, the specimens were
brought to room temperature to avoid severe signal changes
on MR images (7). The heads were positioned in the CT and
MR units, and the examinations were performed in immediate
succession. Dental CT scanning of the mandible consisted of
40 axial sections with a thickness of 1.5 mm and an overlap
of 0.5 mm. Angulation of sections was parallel to the plane of
dental occlusion. The images were calculated with a high-res-
olution algorithm for bone structures.
For dental MR imaging, a turbo gradient-echo technique was
used with parameters of 6.2/20 (TR/TE), a 318 flip angle, a
field of view of 120 mm, and a 128 3 128-voxel matrix. The
section thickness was 1 mm with a 50% overlap and calcula-
tion of 0.5-mm-thick images. The scan time for 101 images
was about 6.2 minutes. A spectral fat-suppression impulse was
introduced into the sequence to minimize signal from fatty
bone marrow. The whole curvature of the mandible was im-
aged in a single scan by using the standard neck quadrature
coil of a 1.0-T MR unit.
The axial CT scans and MR images were reformatted on a
local workstation as panoramic and cross-sectional reconstruc-
tions, using the dental package software in accordance with
the manufacturer’s instructions (EasyVision, Version 2.1 MR
and CT, Philips, the Netherlands). For panoramic reconstruc-
tions, a line following the visible parts of the mandibular canal
was drawn and, every 1 mm, a cross-sectional reconstruction
was calculated (Fig 2). Window and center settings were the
same for all images of a given technique. Thereafter, length
measurements were obtained on reformatted CT and MR cross-
sectional slices. The mandibles were dissected in order to ob-
tain comparable cross sections, such as those evaluated on the
CT and MR reconstructions (Fig 3). The exact anatomic cor-
relation between the cross sections of the specimen and the
cross-sectional CT and MR reconstructions was established by
an anatomist and a radiologist before the measurements were
carried out. Direct osteometry was performed by means of a
slide gauge, and measurements on reformatted CT and MR
images were obtained by comparing distances with the scale
provided on each image. All lengths were determined in mil-
limeters. The results from each technique were assessed in-
dependently by different observers.
Two sets of measurements were obtained in every quadrant
of the mandible. The first set was taken from the cross-sec-
tional image at the level through the mental foramen, the sec-
ond from the cross-sectional image at a point 15 mm posterior
to the mental foramen. From each of these locations the fol-
lowing measurements were obtained: the longest axis in the
bucco-lingual direction of the cross section (the ABL); the lon-
gest axis in the apico-basal direction of a cross section (the
AAB); the distance from the top of the foramen (set 1) or top
of the mandibular canal (set 2) to the top of the alveolar ridge
(the DTT); the distance from the bottom of the foramen (set
1) or bottom of the mandibular canal (set 2) to the base of the
mandible (the DBB); and the diameter of the bone cortex at
the alveolar ridge (the DBC) (Fig 4).
The quality of the data was considered to be rationally
scaled and Pearson’s linear correlation was used to analyze the
correlation of distances. Finally, the differences between com-
parable measurements from corresponding cross sections and
cross-sectional CT and MR images were calculated as direct
osteometry minus dental MR imaging, direct osteometry mi-
nus dental CT, and dental MR imaging minus dental CT. Mean
and standard errors were calculated and, using an analysis of
variance (ANOVA), the significance of differences between
comparable measurements was tested.

AJNR: 20, August 1999 OSTEOMETRY OF THE MANDIBLE 1223
F
IG
3.
A,
Cross-sectional reconstruction of a mandible derived from an axial CT scan with an effective section thickness of 1 mm.
Localization of the mandibular canal (
arrowheads
) was not possible with certainty on this section. A comparison with adjacent sections
was necessary to determine the exact location of the mandibular canal for the measurements.
B,
Cross-sectional reconstruction of the same mandible as in
A,
in the same location, derived from an axial T1-weighted (6.2/20) MR
image (318 flip angle and an effective section thickness of 0.5 mm). The mandibular neurovascular bundle (
arrowheads
) is easily
distinguished on this single section as a moderately hyperintense structure. No additional technique was required for its localization.
C,
Cross section for direct osteometry corresponding to cross-sectional reconstructions in
A
and
B.
The contents of the mandibular
canal were colored with enamel. The location of the mandibular canal (
dark area
) is the same as that identified on the dental MR cross
section. Note that the transition from cortical to spongy bone is not as clear-cut as the reformatted MR and CT images suggest.
F
IG
4. On comparable cross sections, defined distances and di-
ameters were measured on dental MR images and CT scans and
by direct osteometry. Two sets of measurements were obtained in
every quadrant of the mandibles: the first set was taken from the
cross-sectional slice at the level through the mental foramen, the
second from the cross-sectional slice at a point 15 mm posterior to
the mental foramen. The following distances were measured:
ABL,
the longest axis in the bucco-lingual direction of the cross section;
AAB,
the longest axis in the apico-basal direction of a cross section;
DTT,
the distance from the top of the foramen (set 1) or top of the
mandibular canal (set 2) to the top of the alveolar ridge;
DBB,
the
distance from the bottom of the foramen (set 1) or bottom of the
mandibular canal (set 2) to the base of the mandible; and
DBC,
the
diameter of the bone cortex at the alveolar ridge.
Results
The results are summarized in Tables 1 and 2.
Comparison of Direct Osteometry and Dental MR
Measurements
The linear correlation was strong for all distanc-
es, ABL, AAB, DTT, and DBB, with r
2
. .985
(Pearson). The correlation of comparable measure-
ments of the diameter of the bone cortex at the
alveolar ridge (DBC) was moderate, with r
2
5 .64
(Pearson) (Fig 5A and B). The mean difference in
measurements of length between dental MR and
direct osteometry was 0.74 6 1.72 mm (mean 6
SD, differences calculated as direct osteometry mi-
nus dental MR imaging). Comparison of group
means showed no significant difference in mea-
surements between direct osteometry and dental
MR imaging (ANOVA; direct osteometry, CT, and
MR imaging groups: n 5 180; for parameters ABL,
AAB, DTT, DBB, and DBC, P 5 .05, NS). Spec-
tral fat suppression was sufficient. The signal in-
tensity from the neurovascular bundle was slightly
increased compared with the signal intensity nor-
mally observed in patients. The IANB was clearly
visible in all mandibles, but differentiation between
nerve and vessels inside the mandibular canal was
not possible.
Comparison of Direct Osteometry and Dental CT
Measurements
Dental CT scans also showed a strong linear cor-
relation for all the distances, ABL, AAB, DTT, and

AJNR: 20, August 19991224 NAS
˘
EL
TABLE 1: Summary of calculated differences between measure-
ments from direct osteometry, dental MR imaging, and dental CT
Parameter
Difference (mm, mean 6 SD)
Direct
Osteometry
Minus
Dental MR
Direct
Osteometry
Minus
Dental CT
Dental MR
Minus
Dental CT
ABL 0.3 6 1.1 0.2 6 1.2 20.3 6 0.5
AAB 20.1 6 0.7 20.6 6 1.0 20.6 6 0.7
DTT 0.1 6 0.7 20.1 6 1.3 20.1 6 1.1
DBB 0.4 6 0.7 0.2 6 1.0 20.3 6 0.8
DBC 2.9 6 2.4 2.8 6 2.5 20.1 6 0.7
Note.—Column 1 represents the difference between direct osteom-
etry and dental MR measurements, where negative values indicate
overestimation and positive values, underestimation of the distances.
In the same way, differences between measurements of direct osteom-
etry and dental CT (column 2) and dental MR and dental CT (column
3) were calculated. ABL indicates the longest axis in the bucco-lingual
direction of a cross section; AAB, the longest axis in the apico-basal
direction of a cross section; DTT, the distance from the top of the
foramen (set 1) or top of the mandibular canal (set 2) to the top of
the alveolar ridge; DBB, the distance from the bottom of the foramen
(set 1) or bottom of the mandibular canal (set 2) to the base of the
mandible; and DBC, the diameter of the bone cortex at the alveolar
ridge.
TABLE 2: Linear squared correlation coefficient (r
2
; Pearson) of
correlated measurements (columns) obtained by three techniques
(rows)
Correlation, r
2
(Pearson) ABL AAB DTT DBB DBC
Direct osteometry/dental MR 0.998 0.996 0.985 0.990 0.640
Direct osteometry/dental CT 0.997 0.997 0.984 0.994 0.636
Dental MR/dental CT 0.997 0.999 0.984 0.992 0.911
Note.—The linear correlations were excellent for all measurements,
except for the diameter of the bone cortex at the top of the alveolar
ridge (DBC). The transition from cortical to spongy bone, which was
not perfectly smooth, made it difficult to define this diameter on visual
inspection for direct osteometry. ABL indicates the longest axis in the
bucco-lingual direction of a cross section; AAB, the longest axis in
the apico-basal direction of a cross section; DTT, the distance from
the top of the foramen (set 1) or top of the mandibular canal (set 2)
to the top of the alveolar ridge; DBB, the distance from the bottom of
the foramen (set 1) or bottom of the mandibular canal (set 2) to the
base of the mandible; and DBC, the diameter of the bone cortex at
the alveolar ridge.
→
F
IG
5.
A,
Comparison between direct osteometry and dental MR imaging. Measurements obtained by direct osteometry are drawn on
the
x
-axis and corresponding measurements obtained on dental MR images are drawn on the
y
-axis (
diamonds
). Witha 100%correlation
between dental MR and direct osteometry, all dental MR measurements would meet the first median (
straight line
). Overestimations of
distances judged on dental MR images thus lie above and underestimations below the first median. Excellent linear correlationbetween
dental MR imaging and direct osteometry, with nearly all measurements fitting the first median, is shown.
B,
The correlation between direct osteometry and dental MR imaging was only moderate in regard to the diameter of the bone cortex
DBB, with r
2
. .984 (Pearson). The correlation of
the diameter of the bone cortex at the alveolar ridge
(DBC) was only moderate, with r
2
5 .636 (Pear-
son) (Fig 5C and D). The mean difference between
dental CT scans and direct osteometry was 0.51 6
1.91 mm (mean 6 SD, differences calculated as
direct osteometry minus dental CT). Group means
were not significantly different between the various
methods (ANOVA; direct osteometry, CT, MR im-
aging groups: n 5 180; for parameters ABL, AAB,
DTT, DBB, and DBC, P 5 .05, NS). The mandib-
ular canal could be distinguished in all cases, but
comparison with adjacent parallel and correlated
perpendicular sections for localization was neces-
sary in two mandibles.
Correlation of Dental MR with Dental CT
Measurements
There was a strong linear correlation between
dental MR and dental CT for all distances, includ-
ing the bone cortex diameter (DBC), with r
2
.
.911 (Pearson) (Fig 5E and F). The mean difference
between dental MR and dental CT was 20.32 6
0.85 mm (mean 6 SD, differences calculated as
dental MR imaging minus dental CT). Comparison
of group means of corresponding distances showed
no significant difference between the imaging
methods and direct osteometry (ANOVA; direct os-
teometry, CT, MR imaging groups: n 5 180; for
parameters ABL, AAB, DTT, DBB, and DBC, P
5 .05, NS).
Discussion
Axial CT with subsequent cross-sectional and
panoramic reconstruction, known as dental CT, is
widely used in oral surgery (8–11). The main ra-
tionale for using dental CT is to avoid injury to the
IANB, which may occur during surgical procedu-
res. Dental CT has proved useful for the depiction
of the bony structures of the mandibular canal and
its spatial relations inside the mandible. The accu-
racy of dental CT for depicting distances in the jaw
bones has been found to be sufficient for oral sur-
gery (2). Dental MR imaging, a recently introduced
procedure with a resolution comparable to that of
dental CT (5, 6), permits direct visualization of the
IANB. Although bony structures give only low or
no signal on dental MR images, bone is well dif-
ferentiated against the surrounding soft tissue in
terms of a high intensity signal, which allows mea-
surement of distances between bony landmarks.
Furthermore, pathologic alterations, such as edema
or tumor, are well delineated by the soft-tissue con-
trast. Thus, dental MR appears to be a significant
extension of the imaging possibilities of dental CT
(5).
To qualify as a means of planning oral surgery,
dental MR images should depict exactly the dis-

AJNR: 20, August 1999 OSTEOMETRY OF THE MANDIBLE 1225
at the edge of the alveolar ridge (DBC).
C,
Dental CT also shows a strong linear correlation with direct osteometry. The dental CT measurements (
squares
) nearly meet the
first median (
straight line
).
D,
For dental CT measurements, the diameter of the bone cortex at the edge of the alveolar ridge (DBC) was only moderately linearly
correlated with that of direct osteometry.
E,
Dental CT and MR imaging show the strongest linear correlation. Dental MR measurements are drawn on the
y
-axis (
triangles
)
and dental CT measurements on the
x
-axis. Dental MR shows a very slight overestimation of distances (shown as points lying above
the expected first median) compared with dental CT measurements.
F,
Because on dental CT and MR images the transition between cortical and spongy bone appears to be sharp, correlation was
extremely strong for the measurements of the diameter of cortical bone at the edge of the alveolar ridge (DBC), although the correlation
of both techniques with direct osteometry was only moderate. Measurements from dental MR images are drawn on the
y
-axis (
dots
)
and those of dental CT scans on the
x
-axis. With a 100% correlation, all measurements would lie on the first median (
straight line
).

AJNR: 20, August 19991226 NAS
˘
EL
tances within the jaw bones. Since the accuracy of
dental MR imaging has not yet been proved, we
compared this technique with direct osteometry and
dental CT using mandible specimens. The results
showed a strong linear correlation among the three
techniques. The differences in comparable distanc-
es were less than 1 mm on average, and group
means for the defined distances were not signifi-
cantly different.
Although no statistically significant differences
among the three methods were found, the measured
diameter of the bone cortex at the alveolar ridge
(DBC) differed remarkably between dental MR and
direct osteometry. Dental CT was also considerably
different from direct osteometry in regard to the
DBC. As a result, for this measurement, CT and
MR imaging correlated only moderately with direct
osteometry. On the other hand, the correlation be-
tween dental CT and dental MR imaging was clear-
ly strong for this diameter. One reason for these
discrepancies could be the different appearance of
cortical bone on MR and CT reconstructions as
compared with visual inspection by direct
osteometry.
Dental MR and CT reconstructions suggested a
relatively clear-cut transition between compact and
spongy bone in all mandibles, although this was not
consistently observed on visual inspection with di-
rect osteometry. In a grossly anatomic sense, the
transition from compact to spongy bone in the bone
marrow space was not well defined in every spec-
imen. Therefore, it was difficult to define the border
between compact and spongy bone, a delineation
that is necessary in order to measure cortical
diameter.
The limited spatial resolution of dental MR and
CT is such that single bone trabeculae in the tran-
sition zone cannot be clearly differentiated. Addi-
tionally, soft tissue between the trabeculae creates
partial volume artifacts, which mask a part of the
bone in the transition zone. Furthermore, the ne-
cessity of selecting an adequate window also influ-
ences image evaluation, mainly because of partial
volume artifacts, in which voxels with densely
packed bone trabeculae may be depicted as com-
pact bone and those with higher soft-tissue contents
but still containing mineralized bone could be mis-
interpreted as soft tissue of the bone marrow. De-
pending on the window settings, which are always
a compromise aimed at optimal depiction of distin-
guishable details, the transition zone between com-
pact and spongy bone may appear smaller on the
reformatted images than on direct osteometry. Nev-
ertheless, in this study, a maximum window width
with an acceptable depiction of small structures
was chosen.
Finally, although kept to a minimum, smoothing
algorithms of the reconstruction software will also
affect distance evaluations on CT and MR refor-
mations. However, the results show that both im-
aging methods, dental CT as well as dental MR
imaging, appear to be affected in the same way,
which explains the strong correlation between CT
and MR measurements for the DBC. Assuming that
the proposed sequence is used, susceptibility arti-
facts at the interface between compact bone and
soft tissue, which could cause compact bone to ap-
pear more prominent, do not seem to alter pro-
foundly the accuracy of measurements of the di-
ameter of the bony cortex on dental MR images.
Since exact knowledge of the actual DBC will be
of interest primarily for the planning of implants,
dental CT and dental MR imaging will only be at
risk for underestimating the stability of the jaw
bone. However, none of the measured distances, in-
cluding the DBC, was significantly different on
these studies from those obtained by direct osteo-
metry. Moreover, the precision of dental CT mea-
surements was not higher than that of dental MR
imaging. Therefore, dental MR imaging appears to
be sufficiently precise for preoperative osteometry.
Dental imaging may also be limited by artifacts
from dental filling material. Four mandible speci-
mens had metallic fillings. As most of the filling
material was located at the dental corona, and axial
scans were performed, the encountered artifacts
were mainly located in the extraosseous portion of
the teeth. Therefore, a diagnostic assessment of the
jaw bones was possible in all cases. The gradient-
echo turbo field technique with a short TE and a
low flip angle provided sufficiently detailed infor-
mation about the jaw bone structures on the refor-
matted images, with good differentiation of the man-
dibular neurovascular bundle. Artifacts from filling
material were also within an acceptable range.
Conclusion
MR imaging permits sufficiently precise depic-
tion of distances in the jaw bones and is therefore
a useful dental imaging tool. Spatial distortions on
dental MR images were not significantly different
from those on the widely used dental CT scans and
were within an acceptable range for planning sur-
gery in the jaw bones. The advantageous direct de-
piction of soft-tissue structures, such as the inferior
alveolar neurovascular bundle or soft-tissue mass,
combined with the avoidance of radiation exposure,
should encourage further evaluation of MR imag-
ing for practical use in dental radiology.
References
1. Denio D, Torabinejad M, Bakland LK. Anatomical relationship
of the mandibular canal to its surrounding structures in ma-
ture mandibles. Journal of Endodontology 1992;18:161–165
2. Abrahms JJ. Dental implants and multiplanar imaging of the
jaw. In: Som PM, Curtin HD, eds. Head and Neck Imaging. 3rd
ed. St Louis: Mosby; 1996;2:350–374
3. Tamas F. Position of the mandibular canal. Int J Maxillofac Surg
1987;16:65–69
4. Feifel H, Riediger D, Gustorf-Aeckerle R. High resolution com-
puted tomography of the inferior alveolar and lingual nerves.
Neuroradiology 1994;36:236–238
5. Nasel C, Gahleitner A, Breitenseher M, Czerny C, Solar P, Imhof
H. Dental magnetic resonance tomography of the mandible. J
Comput Assist Tomogr 1998;22:498–502

AJNR: 20, August 1999 OSTEOMETRY OF THE MANDIBLE 1227
6. Nasel C, Gahleitner A, Breitenseher M, et al. Localization of
the mandibular neurovascular bundle using dental mag-
netic resonance imaging. Dentomaxillofac Radiol 1998;27:
305–307
7. Ikeda K, Ho K-C, Nowicki BH, Haughton VM. Multiplanar MR
and anatomic study of the mandibular canal. AJNR Am J Neu-
roradiol 1996;17:579–584
8. Rothman SLG, Chaftez N, Rhodes ML, Schwartz M. CT in the
preoperative assessment of the mandible and maxilla for en-
dosseous implant surgery. Radiology 1988;168:171–175
9. Klinge B, Petersson A, Maly P. Location of the mandibular ca-
nal: comparison of macroscopic findings conventional radi-
ography, and computed tomography. Int J Oral Maxillofac Im-
plants 1989;4:327–332
10. Abrahms JJ, Oliverio PJ. Odontogenic cysts: improved imaging
with a dental CT software program. AJNR Am J Neuroradiol
1993;14:367–374
11. Krennmair G, Lenglinger F. Imaging of mandibular cysts with
a dental computed tomography software program. Int J Max-
illofac Surg 1995;24:48–52