High resolution 3-T MR imaging in the evaluation of the trigeminal nerve course

Abstract

The evaluation of the trigeminal course and his anatomical relationships with surrounding structures, is important for the assessment of the injury that may occur in tumors and several orofacial trauma and for avoiding the damage during surgeries.
The aim of this retrospective study was to assess the use of 3-T MRI in the evaluation of the course of the four segments of the trigeminal nerve: cisternal and Meckels's cave, cavernous sinus, skull base and mandibular extracranial segments.
78 patients were studied, for a total of 156 trigeminal nerves examined. T2-weighted 3D Fast imaging employing steady-state acquisition and T1-weighted Fast spoiled gradient recalled echo sequences were used. Two radiologists (reader A and B), independently, evaluated the course of the four segments of the trigeminal nerve according to a qualitative scale. The Intraclass correlation coefficient (ICC) and Pearson correlation coefficient were used to assess the intraobserver and interobserver variability in the nerve course evaluation.
Reader A evaluated 47 trigeminal nerves excellent, 94 good, 12 fair and 3 poor. Reader B rated 43 trigeminal nerves excellent, 92 good, 16 fair and 5 poor. The intraobserver variability was ICC = 0.937 in reader A and ICC = 0.894 in reader B. The interobserver variability was 0.734 (p ≤ 0.01).
High resolution 3-T MRI imaging allows an accurate study of the trigeminal nerve and especially of its mandibular branch. The knowledge of the course and of the anatomic relationships of these nerve bundles with surrounding structures, as well as of the anatomical variants, allow oral and maxillofacial surgical plannings thus reducing the risk of nerve damage.

Full text

Abstract. – BACKGROUND: The evaluation
of the trigeminal course and his anatomical rela-
tionships with surrounding structures, is impor-
tant for the assessment of the injury that may
occur in tumors and several orofacial trauma
and for avoiding the damage during surgeries.
AIM: The aim of this retrospective study was to
assess the use of 3-T MRI in the evaluation of the
course of the four segments of the trigeminal
nerve: cisternal and Meckels’s cave, cavernous si-
nus, skull base and mandibular extracranial seg-
ments.
PATIENTS AND METHODS: 78 patients were
studied, for a total of 156 trigeminal nerves ex-
amined. T2-weighted 3D Fast imaging employ-
ing steady-state acquisition and T1-weighted
Fast spoiled gradient recalled echo sequences
were used. Two radiologists (reader A and B),
independently, evaluated the course of the four
segments of the trigeminal nerve according to
a qualitative scale. The Intraclass correlation
coefficient (ICC) and Pearson correlation coeffi-
cient were used t o as sess the intraobserv er
and interobserver variabi l i t y i n t h e n e r v e
course evaluation.
RESULTS: Reader A evaluated 47 trigeminal
nerves excellent, 94 good, 12 fair and 3 poor.
Reader B rated 43 trigeminal nerves excellent, 92
good, 16 fair and 5 poor. The intraobserver vari-
ability was ICC = 0.937 in reader A and ICC =
0.894 in reader B. The interobserver variability
was 0.734 (p≤≤ 0.01).
CO N CLU S IO N S: High r e s o l u t i o n 3-T M R I
imaging allows an accurate study of the trigem-
inal nerve and especially of its mandibular
branch. The knowledge of the course and of the
anatomic relationships of these nerve bundles
with surrounding structures, as well as of the
anatomical variants, allow oral and maxillofa-
cial surgical plannings thus reducing the risk of
nerve damage.
Key Words:
Magnetic resonance imaging, Trigeminal nerve,
Trigeminal nerve injuries, Mandibular nerve, Tomogra-
phy, X-Ray computed.
European Review for Medical and Pharmacological Sciences
High resolution 3-T MR imaging in the
evaluation of the trigeminal nerve course
M. CASSETTA, N. PRANNO, V. POMPA1, F. BARCHETTI1, G. POMPA
Department of Oral and Maxillofacial Sciences, School of Dentistry, and 1Department of Radiological,
Oncology and Anatomo-Pathological Sciences; “Sapienza” University of Rome, Rome, Italy
Corresponding Author: Michele Cassetta, Ph.D; e-mail: michele.cassetta@uniroma1.it 257
Introduction
The trigeminal nerve is the largest cranial
nerve and the most widely distributed in the
supra-hyoid neck1. It is a mixed sensory-motor
nerve, receiving sensory input from the face and
providing motor innervation to the muscles of
mastication.
The evaluation of the trigeminal course and his
anatomical relationships with surrounding struc-
tures is important for the assessment of the injury
that may occur in tumors and several orofacial
trauma and for avoiding damage during surg-
eries.
A clinical examination using different tests has
thus far been the only established method of di-
agnosing nerve lesions. The using of infrared
equipment and magnetoencepahlography are de-
scribed in some publications to differ between in-
terrupted and intact nerves but these methods,
like other available tests, allow nerve lesions to
be detected only indirectly2,3.
In patients with mandible fracture accompa-
nied by dysesthesia of the lower lip, panoramic
radiographs, and CT show the severe dislocation
of the mandible fracture, but it is impossible to
know whether the nerve is interrupted, which is
very important in designing corrective surgical
procedures4-7.
Magnetic resonance imaging (MRI) can pro-
vide highly detailed anatomical information with
excellent discrimination of the soft tissues, avoid-
ing patient’s exposure to X-rays8. In the previous
studies the limited use of MRI is due to the longer
examination time and the lower resolution that this
method has in comparison with computed tomog-
raphy. Indeed, the insufficient spatial resolution
1.5T MRI cannot display small lesion and detail
small anatomical structures properly.
Some researchers have demonstrated that the in-
troduction of high resolution 3-T MR and opti-
2014; 18: 257-264

258
mized sequences can significantly improve the spa-
tial resolution and the signal-noise ratio (SNR)9-11.
The aim of this retrospective study was to as-
sess the use of 3 T MR imaging in the evaluation
of the course of the trigeminal nerve and espe-
cially of its third mandibular branch.
Patients and Methods
Patient Population
The head and neck MRI scans of 78 patients
(42 males and 36 females; mean age: 57 years;
range: 17 to 71 years) were retrospectively evalu-
ated in the Department of Radiological Science
of “Sapienza” University of Rome, Italy.
The study was approved by the local Ethical
Committee and conducted in accordance with the
Helsinki Declaration of 1975 as revised in 2000.
MR Imaging Acquisition Protocol
All patients underwent an MRI examination
performed using a superconducting magnet of 3
Tesla (Discovery MR750, GE Healthcare, Mil-
waukee, USA) equipped with an 8-channel neu-
rovascular phased-array coil (GE Medical Sys-
tem). The standardized imaging protocol included:
axial T1-weighted TSE sequence; axial T2-
weighted TSE sequence; axial STIR sequence; ax-
ial, coronal and sagittal T1-weighted fat-saturated
sequences after gadolinium injection; T2-weighted
3D-Fast imaging employing steady-state acquisi-
tion (3D FIESTA) and T1-weighted Fast spoiled
gradient recalled echo (fast SPGR) sequences. 3D
FIESTA and fast SPGR sequences were used to
depict the trigeminal nerve course.
Imaging parameters of 3D FIESTA sequence
were as follows: repetition time (TR) = 4.6 ms;
echo time (TE) = 2.2 ms; slice thickness = 0.6
mm; field of view (FOV) = 20 ×20 cm; number
of excitations (NEX) = 1; matrix = 512 ×512.
Imaging parameters of fast SPGR sequence
were as follows: repetition time (TR) = 8 ms;
echo time (TE) = 3 ms; slice thickness = 0.6 mm;
field of view (FOV) = 15 ×21 cm; number of ex-
citations (NEX) = 2; matrix = 512 ×512.
Axial acquisition were obtained for both se-
quences.
MRI Post-Processing and
Image Interpretation
Two experts in oral radiology (reader A with 25
years of experience and reader B with 5 years of
experience) evaluated, independently, the images
of the trigeminal nerve. The images were evaluated
on an off-line dedicated workstation (AW Volume-
Share2, GE Healthcare, Milwaukee, USA). Opti-
mal planes, including the course of the inferior
alveolar nerve (IAN), were determined by means
of multiplanar reformation (MPR) using the im-
ager’s standard reformation software (Figure 1).
The radiologists, to simplify the trigeminal
nerve evaluation, divided the anatomical course
into 4 segments: cisternal and Meckels’s cave,
cavernous sinus, skull base and mandibular ex-
tracranial segments. The course of each segment
was rating as described below:
Unclear course: 1;
Probable recognition of the course: 2;
Definite recognition of the course: 3.
The presence of motion artifacts was rated in
each segment as follows:
Severe artifacts: 1;
Mild artifacts: 2;
None: 3.
The sum of the scores of each component de-
termines, according to the following conversion
scale, the accuracy degree to depict the full
trigeminal nerve course:
Score from 24 to 20: excellent;
Score from 19 to 14: good
Score from 13 to 8: fair;
Score < 8: poor.
After 2 months, the two specialists reassessed
the course of the trigeminal segments in order to
calculate the intraobserver variability.
Statistical Analysis
Data were evaluated using a statistical analysis
software (SPSS®, Statistical Package for Social
Science, IBM Corporation, Armonk, NY, USA).
Qualitative data of accuracy degree in the de-
piction of the trigeminal nerve course (excellent,
good, fair and poor) were described with fre-
quency distribution. To evaluate reproducibility,
the two experts repeated the evaluation of the
trigeminal nerves on two occasions at intervals of
2 months. Intraclass correlation coefficient (ICC)
were used to evaluate intraobserver variability.
Pearson correlation coefficient was used to evalu-
ate the interobserver variability. The significance
was set at p≤ 0.01.
M. Cassetta, N. Pranno, V. Pompa, F. Barchetti, G. Pompa

Figure 1. 3D FIESTA (A-C) and 3D SPGR (D-F) images showing the procedure needed to obtain an optimal plane to display
the IAN. In multiplanar reformation (MPR) technique the reference axis were centered in the proper axial images at the level
of the mandibular third molar with an axis oriented parallel and the other perpendicular to alveolar bone in order to achieve a
parasagittal plane to correctly depict the course of the IAN. C, F, The relationship with the IAN and third molar roots is well
displayed (white arrows).
Qualitative assessment Reader A Reader B
Excellent 47 = 28.8% 43 = 27.6%
Good 94 = 61.6% 92 = 59.1%
Fair 12 = 7.7% 16 = 10.2%
Poor 3 = 1.9% 5 = 3.1%
Table I. Qualitative assessment of full trigeminal course.
High resolution 3-T MR imaging in the evaluation of the trigeminal nerve course
259
ed into 3 branches: ophthalmic, maxillary and
mandibular (Figure 2B). The motor root went
through under the ganglion, turned inferiorly to
exit the skull base together with the mandibular
division of the sensory root12.
In the cavernous segment the ophthalmic and
maxillary divisions continued within the lateral
wall of the cavernous sinus (Figure 2C), below
the cavernous part of internal carotid artery12.
In the skull base segment the ophthalmic divi-
sion leaved the anterior cavernous sinus and exit-
ed the intracranial compartment through the su-
perior orbital fissure (Figure 2D), the maxillary
division exited the central skull base through
foramen rotundum and entered the pterygopala-
tine fossa13 (Figures 2E, F) and the mandibular
division, the largest of the three, exited the skull
base through foramen ovale, entering the na-
sopharyngeal masticator space (Figures 3A, B).
The mandibular peripheral segment gave off 4
sensory branches: buccal, auriculotemporal, lin-
gual and inferior alveolar nerve (IAN). The divi-
Results
The frequency distribution of accuracy degree
in the depiction of the trigeminal nerve segments
course, according to reader A and reader B, is
summarized in Table I.
The cisternal segment was identified at the
ventrolateral midpons where the trigeminal nerve
emerges as two separate roots. The larger sensory
root was located laterally and the smaller motor
root medially (Figure 2A) and penetrated into
Meckel’s cave containing the gasserion ganglion.
The sensory root entered the ganglion and divid-

260
sion of mandibular branch in IAN and lingual
nerve was found 8 mm beneath the foramen
ovale (Figure 3C).
The IAN entered the mandibular canal through
the mandibular foramen (Figure 4A) at the lin-
gual surface of the mandibular ramus and trav-
elled along the body of the mandible (Figures
1C, F, 4B). It divided at the first and second pre-
molars teeth into terminal incisive and mental
branches. The mental nerve emerged at the men-
tal foramen and innervated the skin of the chin
and the mucous membrane of the lower lip (Fig-
ure 4C). The incisive nerve ran from the mental
nerve usually to the region of the ipsilateral in-
cisor teeth (Figure 4D)11. The lingual nerve lied
at first beneath the lateral pterygoid muscle me-
dial to and in f ront of I AN. The nerve then
passed between the medial pterygoid muscle and
the ramus of the mandible, and crossed obliquely
to the side of the tongue ove r the costrictor
pharyngis superior and styloglossus. From there,
it passed between the mylohyoid muscle and the
mucous membrane of the floor of the mouth
along the side of the tongue (Figure 4B).
Both readers were not able to identify the buc-
cal and auriculotemporal branches in all patient.
The intraobserver variability in the evaluation
of the trigeminal nerve course was ICC = 0.937
in reader A and ICC = 0.894 in reader B.
The interobserver variability in the assessment
of the trigeminal segments (Pearson correlation
coefficient) was 0.734 (p≤ 0.01).
M. Cassetta, N. Pranno, V. Pompa, F. Barchetti, G. Pompa
Figure 2. A, Axial 3D FIESTA image through the ponto-mesencephalic junction shows the cisternal segment of the trigemi-
nal nerve travelling through the lateral aspect of the pre-pontine cistern, with the larger sensory root located laterally (black ar-
row) and the smaller motor root placed medially (white arrow). B, Axial 3D FIESTA image through the high pons demon-
strates the nerve entering the medial cranial fossa and penetrating a dural lined sinus filled with cerebro-spinal-fluid, Meckel’s
cave, containing the gasserion ganglion. The sensory root enters the ganglion and divides into 3 branches: ophthalmic, maxil-
lary and mandibular (white arrows). C, Coronal 3D FIESTA image shows the ophthalmic and maxillary divisions of the
trigeminal nerve within the lateral wall of the cavernous sinus (white arrowheads), below the cavernous part of internal carotid
artery. D, Coronal 3D FIESTA image shows the ophthalmic division (black arrow) leaving the anterior cavernous sinus and the
intracranial compartment through the superior orbital fissure (white arrow: oculomotor nerve). E, F, Axial and coronal 3D FI-
ESTA images display the maxillary division of the trigeminal nerve travelling from the inferior cavernous sinus to the ptery-
gopalatine fossa through the foramen rotundum (white arrowheads).

Discussion
To know the course of the cranial nerves be-
fore the surgical planning is of primary impor-
tance to avoid the risk of nerve bundles injury.
In the previous studies, MRI with conventional
field strength did not allow the evaluation of the
course of the cranial nerves (although it has al-
ways been considered the gold standard for the
study of the nervous system), because the con-
ventional 1.5 Tesla magnet is not enable to reach
high spatial resolution so as to acquire images
suitable for the study of the cranial nerves which
have small diameter and tortuous course. Another
drawback is a high incidence of motion artifacts
related to the high interval of time necessary for
the acquisition of the images. Recently, the intro-
du c t ion in t o cl i n ical pr actice o f hi g h - field
strength MR systems (3.0 Tesla) and the use of
fast sequences such as 3D FIESTA, has brought
clear advantages. The main advantage of a 3.0
Tesla magnet is the increasing in the signal-to-
noise ratio, which leads to a gain of the spatial
resolution with improving the q u a l i t y o f
images15. 3D FIESTA allows the acquisition of
images with a submillimetric section thicknesses
in a very short time, with a consequent reduction
of the motion artifacts allowing the study of
smaller structures such as nerve bundles.
An 3D FIESTA sequence is any gradient-echo
sequence in which a nonzero steady state devel-
ops between pulse repetitions for both the longi-
261
High resolution 3-T MR imaging in the evaluation of the trigeminal nerve course
Figure 3. A, B, Axial and coronal 3D FIESTA images show the mandibular division leaving the skull base through foramen
ovale and entering the nasopharyngeal masticator space. C, Axial 3D FIESTA image depicting the division of the mandibular
branch in inferior alveolar nerve (black arrow) and lingual nerve (white arrow) at about 8 mm beneath the foramen ovale. D,
Axial 3D FIESTA image showing the IAN (white arrow), mylohyoid nerve (black arrowhead) braching from the IAN and the
lingual nerve (black arrow) runnig medially to the IAN.

262
tudinal and transverse relaxation values of the in-
terrogated tissues. A small flip angle and short
relaxation time are required for this to occur. The
clinical utility of an 3D FIESTA sequence lies in
its ability to generate a strong signal in tissues
th at have a hig h T 2/T1 rat io, s uch a s cere-
brospinal fluid (CSF) and fat16.
The use of 3.0 Tesla MR imaging with 3D
FIESTA sequence allows to reach a higher spa-
tial resolution and a decrease of motion artifacts,
with a consequent clearer depiction of tiny cra-
nial nerve bundles, showed as low signal intensi-
ty structures.
The main disadvantage of 3D FIESTA imag-
ing is a reduced contrast resolution between hard
and soft tissues that does not allow the visualiza-
tion of peripheral branches inside mandibular
bone. This drawback can be overcome by the use
of T1-weighted fast spoiled gradient recalled
echo (fast SPGR). Fast SPGR is a 3D fast fat sat-
urated T1-weighted sequence which provides a
high contrast between nerve bundles, displayed
as a high signal intensity structure, and bone tis-
sue, depicted as a very low signal intensity struc-
ture (Figures 1F, D).
This study has been focused on the trigeminal
nerve and especially on the mandibular branch.
Indeed the knowledge of the IAN and the lingual
nerve course (the two main branches of the
mandibular nerve) is of a great importance in oral
M. Cassetta, N. Pranno, V. Pompa, F. Barchetti, G. Pompa
Figure 4. A, Axial 3D FIESTA image shows the IAN (white arrow) entering the mandibular canal through the mandibular
foramen at the lingual surface of the mandibular ramus. B, Axial 3D FIESTA image displays the IAN (white arrow) travelling
along the body of the mandible and the lingual nerve (black arrow) running between the mylohyoid muscle and the mucous
membrane of the floor of the mouth along the side of the tongue. C, Coronal 3D FIESTA image shows the mental nerve (white
arrowheads) emerging at the mental foramen and entering into the soft-tissues of the chin and the lower lip. D, Axial fast SP-
GR image shows the IAN (white arrowheads) travelling along the body of the mandible, the mental foramen (white arrow) and
the incisive nerve (black arrowheads) running from the mental nerve to the region of the ipsilateral incisor teeth.

and maxillofacial surgery, because they are at risk
of injury that may occur in tumors, trauma and
several orofacial surgical procedures such as ex-
traction of the mandibular third molar, orthog-
nathic surgery of the mandible17-21, root canal
treatment, block anesthesia and dental implant
surgery22. The damage of these nerve trunks may
result in neurosensory impairment ranging from
the complete anesthesia to the more common par-
tial loss of sensitivity.
In the past, during orofacial surgeries, the
knowledge of anatomy of the lingual and inferior
alveolar nerves was based only on data derived
from surveys carried out on basic studies on ca-
daveric mandibles23. For this reason any informa-
tion about anatomical variations was not provid-
ed therefore the risk of the damage of the nerve
bundles was al ways present . De t ailed MRI
anatomical studies, however, would provide the
surgeon with the exact knowledge of the course
of these nerves and the relationships with local
anatomical landmarks and any existing variants
allowing surgical planning to be designed safely
and thus avoiding possible nerve injuries.
The high intraobserver ICCs and high interob-
server Pearson correlation coefficient found in
this study indicate high degree of reliability and a
high level of reproducibility in the evaluation of
trigeminal nerve course.
Our findings suggest that the MRI study of the
trigeminal nerve course could get into the routine
surgical planning with all the important advan-
tages that can result in clinical practice; for in-
stance the distance of the IAN to the apices of
the teeth or the alveolar ridge can be measured
and this can decrease the possibility of nerve in-
jury in dental implant and extraction of the third
molars (Figures 1C, F).
Conclusions
The use of 3.0 T MRI with 3D FIESTA and
fast SPGR sequences allowed the study of the
course of the trigeminal nerve and its branches.
The knowledge of the course and of the anatomic
relationships of these nerve bundles with sur-
rounding structures, as well as of the anatomical
variants, allow oral and maxillofacial surgical
plannings thus reducing the risk of nerve dam-
age. The reduced appearance of this complication
provides advantages both for the patient, in terms
of safety, and for the physician, in terms of
medico-legal consequences.
–––––––––––––––––-––––
Conflict of Interest
The Authors declare that there are no conflicts of interest.
References
1) WILLIA MS LS, SCHMALF USS IM, SISTROM CL, INOUE T,
TANAKA R, SEOANE ER, MANCUSO AA. MR imaging of
the trigeminal ganglion, nerve, and the perineural
vascular plexus: normal appearance and variants
with correlation to cadaver specimens. AJNR Am
J Neuroradiol 2003; 24: 1317-1323.
2) MCDONALD AR, ROBERTS TP, ROWLEY HA, POGREL MA.
Noninvasive somatosensory monitoring of the in-
ju red i nferio r alveolar nerve u sin g m agn eti c
source imaging. J Oral Maxillofac Surg 1996; 54:
1068-1072.
3) GRATT BM, SHETTY V, SAIAR M, SICKLES EA. Electronic
thermography for the assessment of the inferior
alveolar nerve deficit. Oral Surg Oral Med Oral
Pathol Oral Radiol Endod 1995; 80: 153-160.
4) TANTAN AP ORNKU L W, OKO UC HI K, FUJI WA RA Y, YA-
MASHIRO M, MARUOKA Y, OHBAYASHI N et al. A com-
parative study of cone-beam computed tomogra-
phy and conventional panoramic radiography in
assessing the topographic relationship between
the mandibular canal and impacted third molars.
Oral Surg Oral Med Oral Pathol Oral Radiol En-
dod 2007; 103: 253-259.
5) SUSARLA SM, DODSON TB. Preoperative computed
tomography imaging in the management of im-
pacted mandibular third molars. J Oral Maxillofac
Surg 2007; 65: 83-88.
6) CASSETTA M, STEFANELLI LV, DICARLO S, POMPA G, BAR-
BATO E. The accuracy of CBCT in measuring jaws
bone density. Eur Rev Med Pharmacol Sci 2012;
16: 1425-1429.
7) CASSETTA M, STEFANELLI LV, GIANSANTI M, DIMAMBRO
A, CALASSO S. Accuracy of a computer-aided im-
pl a nt surg i c al tech n ique . In t J Perio d onti c s
Restorative Dent 2013; 33: 317-325.
8) MAZZA D, MARINI M, IMPARA L, CASSETTA M, SCARPATO
P, BARCHETTI F, DIPAOLO C. Anatomic examination of
the upper head of the lateral pterygoid muscle us-
ing magnetic resonance imaging and clinical data.
J Craniofac Surg 2009; 20: 1508-1511.
9) DENG W, CHEN SL, ZHANG ZW, HUANG DY, ZHANG X,
LIX. High-resolution magnetic resonance imaging
of the inferior alveolar nerve using 3-dimensional
magnetization-prepared rapid gradient-echo se-
quence at 3.0T. J Oral Maxillofac Surg 2008; 66:
2621-2626.
10) CASSETTA M, DICARLO S, PRANNO N, STAGNITTI A, POMPA
V, POMPA G. The use of high resolution magnetic
resonance on 3.0-T system in the diagnosis and
surgical planning of intraosseous lesions of the
jaws: preliminary results of a retrospective study.
Eur Rev Med Pharmacol Sci 2012; 16: 2021-2028.
11) GOJL, KIM PE, ZEE CS. The trige minal n erve.
Semin Ultrasound, CT, MR 2001; 22: 502-520.
263
High resolution 3-T MR imaging in the evaluation of the trigeminal nerve course

264
12) Bor ges A , Casse lman J. Imag ing the cra nial
nerves part I: methodology, infectious and inflam-
matory, traumatic and congenital lesions. Eur Ra-
diol 2007; 175: 2112-225.
13) BORGES A, CASSELMAN J.Imaging the cranial nerves
part II: primary and secondary neoplastic condi-
tions and neurovascular conflicts. Eur Radiol
2007; 17: 2332-2344.
14) BORGES A. Trigeminal nevralgia and facial nerve
paralysis. Eur Radiol 2005; 15: 511-533.
15) FISCHBACH F, MÜLLER M, BRUHN H. Magnetic reso-
nance imaging of the cranial nerves in the poste-
rior fossa: a comparative study of T2-weighted
spin-echo sequences at 1.5 and 3.0 tesla. Acta
Radiol 2008; 49: 358-363.
16) CHAVHAN GB, BABYN PS, JANKHARIA BG, CHENG HL,
SHROFF MM. Steady-state MR imaging sequences:
physics, classification, and clinical applications.
RadioGraphics 2008; 28: 1147-1160.
17) CASSETTA M, DICARLO S, GIANSANTI M, POMPA V, POM-
PA G, BARBATO E. The impact of osteotomy tech-
nique for corticotomy-assisted or thodontic treat-
ment (CAOT) on oral health-related quality of life.
Eur R ev Me d Phar macol Sci 2012; 16: 1735-
1740.
18) CASSETTA M, DIMAMBRO A, GIANSANTI M, STEFANELLI
LV, BARBATO E. Is it possible to improve the accura-
cy of implants inserted with a stereolithographic
surgical guide by reducing the tolerance between
mechanical components? Int J Oral Maxillofac
Surg 2013; 42: 887-890.
19) CASSETTA M, POMPA G, DICARLO S, PICCOLI L, PACIFICI
A, PACIFICI L. The influence of smoking and surgical
technique on the accuracy of mucosa-supported
stereolithographic surgical guide in complete
edentulous upper jaws. Eur Rev Med Pharmacol
Sci 2012; 16: 1546-1553.
20) CASSETTA M, RICCI L, IEZZI G, DELL'AQUILA D, PIATTELLI
A, PERROTTI V. Resonance frequency analysis of
implants inserted with a simultaneous grafting
procedure: a 5-year follow-up study in man. Int J
Periodontics Restorative Dent 2012; 32: 581-589.
21) TATULLO M, MARRELLI M, CASSETTA M, PACIFICI A, STE-
FANELLI LV, SCACCO S, DIPALMA G, PACIFICI L, INCHINGO-
LO F. Platelet Rich Fibrin (P.R.F.) in reconstructive
surgery of atrophied maxillary bones: clinical and
histological evaluations. Int J Med Sci 2012; 9:
872-880.
22) TERU MIT SU M, SEO K, MATSUZAWA H, YAMAZA KI M,
KWEE IL, NAKADA T. Morphologic evaluation of the
inferior alveolar nerve in patients with sensory
disorders by high-resolution 3D volume rendering
magnetic resonance neurography on a 3.0-T sys-
tem. Oral Surg Oral Med Oral Pathol Oral Radiol
Endod 2011; 111: 95-102.
23) IKEDA K, HOKC, NOWICKI BH, HAUGHTON VM. Multi-
planar MR and anatomic study of the mandibular
canal. AJNR Am J Neuroradiol 1996; 17: 579-584.
M. Cassetta, N. Pranno, V. Pompa, F. Barchetti, G. Pompa