Oblique Sagittal Sectional Anatomy And MR Scanning Study Of Tympanic And Mastoid Segment Of Facial Nerve

PART ONE: Study of MR scanning of temporal bone about tympanic and mastoid segment of facial nerveBackgroundAs we all known,anatomy of the facial nerve is very complex.The tympanic and mastoid segment of facial nerve are the most complicated part because of it's tiny and the overlapping structures surrounding.At present,the overall level of the microsurgical of ear in our country is lower.Many basic and clinical researches can not carry through.There haven't been an identical standard of the diagnosis,treatment,prognosis of the facial nerve diseases. Though of the surgical indications,time of the operation and evaluation of the operations.How to make good images of the tympanic and mastoid sections of facial nerve is the goal of both scholars of Otolaryngology and Radiology.Ordinary X-ray examination is very limited to facial nerve imaging. With the development of medical imaging technology,imaging and display technology of the tympanic and mastoid segment of facial nerve have been making considerable progresses.Especially in recent years,advanced technology of CT and MR make it sure to get more clear images of the tympanic and mastoid segment of facial nerve.To study the imaging anatomy of the tympanic and mastoid segment of facial nerve can provide valuable references to observations and diagnosis of ear diseases.More and more people are concerned about this.There are both advantages and disadvantages of CT and MRI to the diagnosis of facial nerve lesions.CT imaging is good for osseous structures,especially high-resolution CT scan can make clearly thin layer image of facial nerve intra-temporal bone.With the using of spiral CT and the three-dimensional reconstruction technique,it is possible to show the tiny structures of ear.Especially the using of curved-planar reconstruction (CPR)technique with a multi-slice spiral CT takes good advantage of this. CPR can image along the curve of our interested structures.Multi-dimensional CT and post-processing technology provide a good method to obtain a particularly observation of the facial nerve canal.The facial nerve canal within the structures of bilateral temporal bone showed at the same time.It allows us to make detailed morphological observations and measurements of it through the images.It is proved to be the best imaging method of the facial nerve canal up to the present.However,CPR technology is not ideal.The principle of CPR is the rearrange of original data on an axial plane at different levels to recompose a new dimension image with computer.It is to say,CPR is a method to make the tortuous course of the facial nerve canal straightened and displayed in a planar images.So the quality of CPR images is not as good as that of direct scanning images.It is a virtual structure of the facial nerve canal.Morphology of CPR image of the tympanic and mastoid segment of facial nerve is different from the true state of it.Besides,CPR techniques described are highly dependent on the skill level and the accuracy of the curve. Inaccurate position criterion of the aim structure may lead to offset curves. MRI takes advantages of non-invasive,direct multi-planar imaging,excellent soft-tissue resolution and no-hardening artifact which compared to CT.It is increasingly becoming an important facial nerve disease screening method. However,fewer reports of the MR imaging of tympanic and mastoid segment of facial nerve are found.We haven't found any detailed and complete documentations of MR imaging of the tympanic and mastoid segment of facial nerve by far.In this study,we use an advanced 3.0 T MR scanning equipment and hope to make investigations of the tympanic and mastoid segment of facial nerve.We hope to get a good MR scanning criterion so that we can get clear images of the tympanic and mastoid segment of facial nerve.It allows us to perform all-around observations of the tympanic and mastoid segment of facial nerve. So we can get the results of MR imaging methods,imaging features of its anatomy and some measurement results in order to provide clinical references of facial nerve disease.Objective:1,To study the best position and method of MR scanning of the tympanic and mastoid segment of facial nerve.2,To study the features of MR images of the tympanic and mastoid segment of facial nerve.3,Make measurements and observations of the MR images of the tympanic and mastoid segment of facial nerve.Materials and methods1,Tissues sampleWe choose 20(40 sides)temporal bones of adults without any significant diseases of skull.Before our experiment,all the temporal bones are formalin-fixed.There are 11 male and 9 female cases.All specimens come from the Department of Anatomy of Qingdao Medical College.2,MR Scanning2.1 scanning parameter We use a GE 3.0T MR scanning equipment,head coil and 3D-Fast Image Employing Steady-state Acquisition(3D-FIESTA)to finish our imaging.Scanning parameters are as follows:repetition time(TR):4.4ms, echo time(TE):Min,Flip angle(FA):55,Scanning field(FOV):20, Bandwidth:62.50,Thickness 1.6 mm,Matrix:320×320,Stimulate number:2, Position number of each layer:302.2 scanning methodFirst,all specimens are given a general MR axial scanning.After the scanning finished,we select the plane which the tympanic segment of facial nerve showed well and then conduct an oblique sagittal scanning.Write down the data we got of the best scanning plane.3,Measurement methodWe get the MR images through using 3D-Fast Image Employing Steady-state Acquisition.Then we choose the right layer which the whole tympanic and mastoid segment of facial nerve showed well and allowed to make measurements.All data are measured three times for the average.4,StatisticallyWe choose a SPSS 12.0 statistical package on the data for statistical analysis to get the normal range and noted the experimental results to mean±standard deviation.One-way ANOVA is used to compare the data of two sides.Results:1.All the tympanic and mastoid segment of facial nerve of 20 temporal bone specimens(40sides)displayed well.Oblique sagittal MR scanning makes it sure to observe the complete image of the tympanic and mastoid segment of facial nerve.We can observe the image of the tympanic and mastoid segment of facial nerve clearly and get more details about it through this position.2,In our study,20 patients(40 sides)had an oblique sagittal scanning,then we measured the angle between the oblique sagittal scanning line with the median sagittal line and the angle intilted from the oblique sagittal scanning plane.We choose the best plane of the tympanic and mastoid segment of facial nerve to make our measurements of length and diameters.Conclusion:1,Oblique sagittal scanning of MR is the best method to show the tympanic and mastoid segment of facial nerve.2,The angle between the oblique sagittal scanning line and the median sagittal line is 24.54°±4.59°,the angle intilted from the oblique sagittall scan plane is 5.97°±2.32°.3,Measurement results of length and diameters and general anatomy observations are accord to that reported in the literature.PART TWO: Oblique sagittal sectional anatomy of the tympanic and mastoid segment of facial nerve BackgroundAs we all known,anatomy of the facial nerve is very complex.The tympanic and mastoid facial nerve is the most complicated part because of it's tiny and the overlapping structures.MRI takes good advantage of non-invasive,direct multi-planar imaging,excellent soft-tissue resolution and no-hardening artifact which compared to CT.It is increasingly becoming an important facial nerve disease screening method.However,better identification and analysis of the MR image of the tympanic and mastoid segment of facial nerve need the help of the thin specimens sectional anatomy study.In resent years,some scholar mentioned about the oblique sagittal plan except the axial plan,coronal plan and the sagittal plan.But no one make any study about it.We found only one report written by Duan Ju-ru and Wang Shao-yu to study the sectional anatomy on transversal plane of tympanic and mastoid segment of facial nerve and compared it with the same CT images. They found the thin sections of the temporal bone can clearly delineate the anatomical details of the temporal bone and their relationships.The same specimen images post-processed by multi-planar reformation(MPR)came to coincidence completely with these sections.The thin sectional images of the temporal bone obtained by using computerized cryo-milling technique matched well with the CT images.It will be the base of study of the temporal bone and the facial nerve.We haven't searched any detailed documents of oblique sagittal sectional anatomy of the tympanic and mastoid segment of facial nerve so as those compared with the same MR images.In our research,we use an advanced 3.0 T MR scanning equipment and hoped to get clear images of the tympanic and mastoid segment of facial nerve. Then we obtain the sectional data of the tympanic and mastoid segment of facial nerve using computerized cryo-milling technique.All the specimens were sliced into 0.4mm continuous sections with the computerized miller at the same condition as oblique sagittal MR scanning.Take photographs with digital camera,save the data into computer,then compare them with the same specimen's MR images so that to provide references to clinical.We hoped to improve the whole level of diagnosis,operation and treatment of facial nerve diseases.Objective:1,To obtain the oblique sagittal MR images of the tympanic and mastoid segment of facial nerve by using a 3.0 T MR scanning equipment.2,To obtain the oblique sagittal sectional data of the tympanic and mastoid segment of facial nerve by using computerized cryo-milling technique at the same condition as oblique sagittal MR scanning.3,To compare the thin oblique sagittal sectional images of the temporal bone obtained by computerized cryo-milling technique with the same MR images, so that to confirm the results we got from MR scanning of temporal bones and hope it may be the anatomy bases of studies of the temporal bone and the facial nerve.Materials and methods1,Tissues sampleWe choose 20(40 sides)temporal bones of adults without any significant diseases of skull.Before our experiment,all the temporal bones are formalin-fixed.There are 11 male and 9 female cases.All specimens come from the Department of Anatomy of Qingdao Medical College.2,MR Scanning2.1 scanning parameter We use GE 3.0T MR scanner,head coil and 3D-Fast Image Employing Steady-state Acquisition(3D-FIESTA)to finish our imaging. Scanning parameters are as follows:repetition time(TR):4.4ms,echo time (TE):Min,Flip angle(FA):55,Scanning field(FOV):20,Bandwidth:62.50, Thickness 1.6 mm,Matrix:320×320,Stimulate number:2,Position number of each layer:302.2 scanning methodFirst,all specimens are given a general axial scanning.After the scanning finished,we select the plane which the tympanic segment of facial nerve showed well and conduct an oblique sagittal scanning.Write down the number of the angle and the scanning plan of each specimen to prepare for sectional anatomy.3,Computerized Cryo-milling Technique3.1 Freezing,Embedding and ImmovablyWe collect 20 temporal bone specimens of Chinese adults.All specimens are freezing under profound hypothermia after an examination with 3.0T MR scanning.The temperature is-20℃,-30℃,-40℃in turn and each for two days.Then buried with an embedded bag of stainless steel,fixed-position, filling the embedded bag with three percent of the blue gelatin solution to be 7cm apart from the bottom of the embedded bag,then freeze it and make it solidify and stiffen for 24h.All specimens are fixed at the same position with which measured from MR scanning.Specimens were fixed with self-holder positioning and put in the embedded containers after which adding blue gelatin solution to the embedded box in turn for the second,third,fourth times. 24 hours time interval each time.3.2 Computerized Milling Computerized milling carried through in the milling room which keeping the temperature on-15℃.Put the specimens on the block of SKC500 with which milling accuracy is 0.001 mm.Fixed the specimen block and adjusted the distance of Z-axis of each milling time,and spindle speed 900 times/min,every rotation on X-axis direction to a distance of 0.4mm/time. When each layer finished,it stopped at end of the largest negative side of X-axis milling.At the same time,a collection box with counter,scale and color card come into the right position where the specimens will receive some treatment and prepare for photography.3.3 Preservation and PhotographCanon EOS 200D camera installed hood was used to take photographs of the sectional images.Adjust the vertical distance from the camera to the specimen section is 95 cm.When a whole milling procedures completed,tip of the milling machine stopped at the end of largest negative side of X-axis.We use Canon Utilities EOS Capture software control the camera,then take photos and save it into the computer.4,Compare the Sectional images with MR imagesAll the specimens were sliced into 0.4mm continuous sections on an oblique sagittal plane with the computerized miller,take photographs with digital camera and save the data in computer.Photoshop software are used to make the sectional images look to be the best,then compare them with the same specimens MR images so that to provide reference to clinical.Results:1,All the tympanic and mastoid segment of facial nerve of 20 temporal bone specimens(40sides)are well displayed through oblique sagittal sectional anatomy study by using computerized cryomilling technique.We can observe the complete image of the tympanic and mastoid segment of facial nerve clearly.2,Images come from computerized milling are so clear that allow good observations of the tympanic and mastoid segment of facial nerve.All images matched well with the images of MR scanning.Conclusion:1,The results of oblique sagittal sectional anatomy study by using computerized cryomilling technique indicate that the positions and data we got from oblique sagittal MR scanning are believable.2,All results we got can provide important references to clinical application of facial nerve researches.PART THREE: Anatomy and measurements of normal tympanic and mastoid segment of facial nerve by using an oblique sagittal MR scanning techniqueBackgroundFacial nerve is the longest nerve that existed in the canal.It is also the most complicated part of our body.How to make good images of the tympanic and mastoid sections of facial nerve is the goal of both scholars of Otolaryngology and Radiology.Most facial paralyzes are caused by lesions in the temporal bone.Research of the facial nerve intra-temporal bone and the relationship with the surrounding structures is important to diagnosis and treatment of facial nerve diseases.Selection of operation mode of facial nerve decompression,some operations of the ear requires good control of the anatomy of facial nerve and it's surroundings.A successful conduct of the facial nerve and ear operations depend highly on anatomy.So familiar with the facial nerve and the normal variation of the surgery to avoid ear damage accidents is extremely important to clinical value.We can not observe the tympanic and mastoid facial nerve clearly by using traditional image technique for a long time.Ordinary X-ray examination is very limited to facial nerve imaging.CT imaging is good for osseous structures.MRI takes advantages of non-invasive,direct multi-planar imaging, excellent soft-tissue resolution and no-hardening artifact which compared to CT.It is increasingly becoming an important facial nerve disease screening method.General MR scanning plane of facial nerve are axial scanning and coronal scanning.Axial MR scanning may show the geniculation ganglion and the tympanic segment of facial nerve on one same layer.The tympanic segment of the facial nerve is not in one plane,so we can see it in several planes.The mastoid segment of the facial nerve was only a point in the axial plane.Therefore general axial scanning revealed that it is not the best scanning plane of the facial nerve.Coronal scanning can only show the whole mastoid segment of the facial nerve.Therefore the conventional axial and coronal scanning are both not imaging the facial nerve well.It is difficult to find some small focus under this condition.Multi-dimensional CT and post-processing technology provide a good method to obtain a particularly observation of the facial nerve canal.But it can not give us the true state of facial nerve.Oblique sagittal scanning reported in the literature said that we can see the geniculation ganglion,the tympanic segment and the mastoid segment of the facial nerve in one plane which can also show the relationships with vestibular,cochlea and the semicircular canal clearly.Theodora Dailiana et al.had given us an idea of oblique sagittal MR scanning but did not give a detailed description.Zhang Xiao-Hong reported a research about MR scanning with 1.5 T MR of 15sides healthy people and 3 sides of temporal bone to study the MR images of the facial nerve.In the report,they use a small number of cases and a scanning thickness of 3.0 mm and received poor image quality.We haven't searched any detailed and complete documentation of MR imaging of the tympanic and mastoid facial nerve.From researches of ourselves of MR scanning of temporal bones,we considered the oblique sagittal scanning is the best way to show the tympanic and mastoid segment of facial nerve.We choose 50(100sides)healthy people to conduct the research.In this study,we use an advanced 3.0 T MR scanning equipment and hope to make investigations of MR images of the tympanic and mastoid segment of facial nerve.We hope to get a good MR scanning method so that we can get clear images of the tympanic and mastoid segment of facial nerve.It allows us to perform all-around observations of the tympanic and mastoid segment of facial nerve.So we can get the results of MR imaging methods,imaging features of its anatomy.The results we get from the study can provide references to clinical diagnosis treatment and surgery of facial nerve disease.Objective:1,To obtain the best MR scanning plane,scanning position and complete images of the tympanic and mastoid segment of facial nerve of healthy people.2,Make detailed measurements and observations of the MR images of the tympanic and mastoid segment of facial nerve. 3,Make statistical analysis of measurement results and compare the results with those come from MR scanning of the temporal bone.We hope to confirm our technique results through this method.Materials and methods1,Tissues sampleWe choose 50(100 sides)healthy adults without any significant diseases of ears.There are 26 male and 24 female cases.The average age is 45.3.All the people are choose by doctors of Otolaryngology.2,MR Scanning2.1 scanning parameterWe use GE 3.0T MR scanning equipment,head coil and 3D-Fast Image Employing Steady-state Acquisition(3D-FIESTA)to finish our imaging. Scanning parameters are as follows:repetition time(TR):4.4ms,echo time (TE):Min,Flip angle(FA):55,Scanning field(FOV):20,Bandwidth:62.50, Thickness 1.6 mm,Matrix:320×320,Stimulate number:2,Position number of each layer:302.2 scanning methodFirst,all people are given a general axial MR scanning.After the scanning finished,we select the plane which the tympanic segment of facial nerve showed well.The oblique sagittal plane we choose is the plane which paralleled with it.An oblique sagittal MR scanning of the facial nerve will going on the plane which we have selected.3,Measurement methodWe get the MR images through using 3D-Fast Image Employing Steady-state Acquisition.Then we choose the right layer which the whole tympanic and mastoid segment of facial nerve showed well and allowed to make measurements.All data are measured three times for the average.4,StatisticallyWe choose a SPSS 12.0 statistical package on the data for statistical analysis to get the normal range and noted the experimental results to mean±standard deviation.One-way ANOVA is used to compare the data of normal people with that of the temporal bone.Results:1.All 50 people(100sides)of the tympanic and mastoid segment of facial nerve are well displayed.The tympanic and mastoid segment of facial nerve showed a clear and detailed anatomy image through oblique sagittal MR scanning.Oblique MR imaging scan make it sure to observe the complete image of the tympanic and mastoid segment of facial nerve.2,In our study,50 normal people(100 sides)had an oblique sagittal scanning,then we measured the angle between oblique sagittal scanning line and the median sagittal line and the angle intilted from the oblique sagittal scanning plane.We choose the best plane to make our measurements of length and diameters.Conclusion:1,Oblique sagittal scanning of MR is the best method to show the tympanic and mastoid segment of facial nerve.The result is the same as that comes from MR scanning and sectional study of the temporal bone of tympanic and mastoid facial nerve. 2,The angle between the oblique sagittal scanning line and the median sagittal line is 23.67~0±5.46~0,the angle intilted from the oblique sagittal scanning plane is 6.15~0±3.30~0.One-way ANOVA is used to compare the data of normal people with that of the temporal bone.There have no evidently differences from statistic.3,Measurement results and general anatomy observations are accord to that reported in the literature.