Clinically relevant human temporal bone measurements using novel high-resolution cone-beam CT

Clinically ele an human empo al bone measu emen s using no el high- esolu ion cone-beam CT Jing Zou a,b, *, Jaakko L€ ahelm€ a c , An i A nisalo d , Ilma i Pyykk€ o b a Depa men o O ola yngology-Head and Neck Su ge y, Cen e o O ola yngology-Head &Neck Su ge y o Chinese PLA, Changhai Hospi al, Second Mili a y Medical Uni e si y, Shanghai, China b Hea ing and Balance Resea ch Uni , Field o O o-la yngology, School o Medicine, Uni e si y o Tampe e, Tampe e, Finland c Planmeca Oy, Helsinki, Finland d Depa men o O o hinola yngology-Head and Neck Su ge y, Helsinki Uni e si y Cen al Hospi al, Helsinki, Finland Recei ed 16 Decembe 2016; e ised 12 Janua y 2017; accep ed 16 Janua y 2017 Abs ac Objec i e: To es he easibili y o measu ing ine empo al bone s uc u es using a newly es ablished cone-beam compu ed omog aphy (CBCT) sys em. Ma e ials and me hods: Six o malin- ixed human cada e empo al bones we e imaged using a high- esolu ion CBCT sys em ha has 900 ames and coppe þaluminum il a ion. Fine empo al bone s uc u es, including hose o he acial ne e canal and es ibula s uc u es, we e iden i ied and measu ed. Resul s: The ine s uc u es o he middle ea , including he ympanic memb ane, endon o he enso ympani, cochlea i o m p ocess o he semicanal o he enso ympani, py amidal eminence, oo pla e o he s apes, ull pa h o he acial ne e wi hin he empo al bone, sup a- laby in hine space, semici cula canals, pa hway o he suba cua e canal, and ull pa h o he es ibula aqueduc , we e clea ly demons a ed. The es ibula aqueduc has a midpoin wid h o 0.4 ±0.0 mm and ope cula wid h o 0.5 ±0.1 mm (mean ±SD). The leng h o he in e nal acous ic mea us was 10.6 ±1.2 mm (mean ±SD), and he diame e o he in e nal acous ic mea us was 3.7 ±0.3 mm (mean ±SD). Conclusion: This no el high- esolu ion CBCT sys em has po en ially b oad applica ions in he diagnosis o inne ea disease and in moni o ing associa ed pa hological changes, su gical planning, na iga ion o he ea su ge y, and empo al bone aining. Copy igh ©2017, PLA Gene al Hospi al Depa men o O ola yngology Head and Neck Su ge y. P oduc ion and hos ing by Else ie (Singapo e) P e L d. This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/). Keywo ds: CT; Tempo al bone ana omy; Ves ibule; Facial ne e 1. Backg ound Supe io o mul i-de ec o compu ed omog aphy (MDCT), cone-beam CT (CBCT) has as da a acquisi ion (less han a minu e e sus se e al minu es o MDCT), low-dose exposu e o he subjec , smalle loo a ea oo p in o he imaging appa a us, a ela i ely low equipmen pu chase p ice, and has b oad applica ions in head and neck imaging (S u zki e al., 2015). The excellence o CBCT in empo al bone imaging has been demons a ed including isualiza ion o he in a- scala posi ions o cochlea implan elec odes and acial ne e canal measu emen s and po en ial diagnosing semi- ci cula canal dehiscence (Eibenbe ge e al., 2014; Huss ed e al., 2002; Komo i e al., 2013; Pea l e al., 2014; Ve bis e al., 2005; Zou e al., 2015b). E en a p o o ype sys em o in aope a i e CBCT imaging has been de eloped o ack he d ill du ing empo al bone su ge y (E o ic e al., 2013). *Co esponding au ho . Depa men o O ola yngology-Head and Neck Su ge y, Changhai Hospi al, Second Mili a y Medical Uni e si y, Changhai Road #168, Shanghai, 200433, China. E-mail add esses: [email p o ec ed],Jing.Zou@u a. i (J. Zou). Pee e iew unde esponsibili y o PLA Gene al Hospi al Depa men o O ola yngology Head and Neck Su ge y. A ailable online a www.sciencedi ec .com ScienceDi ec Jou nal o O ology 12 (2017) 9e17 www.jou nals.else ie .com/jou nal-o -o ology/ h p://dx.doi.o g/10.1016/j.jo o.2017.01.002 1672-2930/Copy igh ©2017, PLA Gene al Hospi al Depa men o O ola yngology Head and Neck Su ge y. P oduc ion and hos ing by Else ie (Singapo e) P e L d. This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/). Fo bo h diagnosing he middle and inne ea diseases and in aope a i e acking o he d ill du ing empo al bone su - ge y, i is necessa y o ob ain images wi h high spa ial eso- lu ion. B emke e al. epo ed isualiza ion o expe imen al supe io semici cula canal dehiscence (SSCD) using a CBCT wi h oxel esolu ion (sec ion hickness) o 0.125 mm (B emke e al., 2015). Al hough CBCT was signi ican ly be e han MDCT in iden i ying a hin bony co e age o a supe io semici cula canal (SSC), he eliabili y o he adiological indings does no legi ima e he diagnosis o an SSCD based on adiologic da a alone due o exis ence o alse-posi i e esul s. The e is s ill a oom o imp o e he esolu ion o CBCT. We ecen ly designed a no el high- esolu ion CBCT acquisi ion sys em wi h oxel size o 0.1 mm ha in ol es a pause du ing each o he exposu es o he mul iple ames (Fig. 1)(Zou e al., 2015a). The new CBCT sys em p o ided a chance o imp o e he accu acy o diagnosis and in aope a i e acking o he d ill. Aimed o es he easibili y in clinical use, we analyzed he c i ical empo al bone s uc u es, including he es ibula aqueduc , he semici cula canal wall, he acial Fig. 1. Illus a ion o he no el CBCT sys em. The sys em is composed o an imaging pa on he op and a mechanic pla e o m a he bo om. The spaceman was placed on he pla e o m ha o a es. A pause (k) was included in he o a ion du ing each exposu e o pho og aphy. Fig. 2. Middle ea s uc u es o he empo al bone demons a ed by a no el high- esolu ion CBCT sys em in compa ison o he con en ional MDCT. In CBCT,a o al o 900 cone-beam p ojec ions we e acqui ed by o a ing he specimen (le side A, B, and D; igh side E) a ound axial axis and he a ge s uc u es we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes. In MDCT, he iso opic olumes o en i e empo al bone including bo h sides we e acqui ed on axial o ien a ion. The a ge s uc u es we e displayed by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes o he selec ed he le side (C, F). CP: cochlea i o m p ocess; EC: elec ode con ac ; EEC: ex e nal ea canal; S a: s apes; FS a: oo pla e o he s apes; HM; head o malleus; IAM: in e nal audi o y mea us; Ma: malleus; MM: manub ium o malleus; TTT: endon o he enso ympani; SCTT: semicanal o he enso ympani; LPInc: len icula p ocess o he incus; LCInc: long c us o he incus; PE: py amidal eminence; TM: ympanic memb ane; TS-FN: ympanic segmen o he acial ne e; UM: umbo o malleus. Scale ba ¼5 mm. 10 J. Zou e al. / Jou nal o O ology 12 (2017) 9e17 ne e canal and he in e nal mea us, using he newly es ab- lished CBCT sys em. 2. Ma e ials and me hods 2.1. CBCT imaging Six o malin- ixed human cada e empo al bones om deceased Finnish pa ien s we e used in he s udy. All speci- mens we e dona ed o he Uni e si y o Tampe e o scien i ic use and ul illed all equi emen s o he Decla a ion o Hel- sinki, which was de eloped by he Wo ld Medical Associa ion and upda ed a he 64 h WMA Gene al Assembly in Fo aleza, B azil, in 2013 ega ding he e hical use o human ma e ials (Wo ld Medical Associa ion, Inc., 2015). These empo al bones we e ope a ed on o cochlea implan elec ode inse - ion in a p e ious s udy (Zou e al., 2015a, 2015b). The im- aging pa ame e s selec ed o he p esen s udy included he ollowing: numbe o ames, 900; ube ol age, 88 kV; ube cu en , 11 mA; exposu e leng h pe ame, 50 ms; il a ion, 0.5 mm coppe þ2.5 mm aluminum; sou ce- o-image dis- ance, 1 m; magni ica ion ac o , 1.72; oxel size, 0.1 mm; and ield o iew (FOV), 60 60 mm. These pa ame e s we e p e iously op imized (Zou e al., 2015a). 2.2. Image p ocessing The cap u ed X- ay exposu e ames we e econs uc ed using he il e ed backp ojec ion algo i hm. Gamma co ec ion was applied o he econs uc ed images and he p ocessed images we e isualized using he Romexis so wa e e sion 3.0 (Planmeca Oy, Helsinki, Finland). The ine empo al bone s uc u es, including he acial ne e canal and he es ibula s uc u es, we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes. The es ibula aqueduc was con i med by ollowing i s o igin in he es ibule. The sup alaby in h space was e alua ed and speci ically he cou se o he suba cua e canal was ol- lowed om he suba cua e ossa in he pos e io c anial ossa o he mas oid an um. The wall hickness o he semi- ci cula canal a he hinnes si e, he wid h o es ibula aqueduc a midpoin and ope cula poin , he diame e o he acial ne e canal a he na owes si e in he laby in hine segmen , and he diame e and leng h o he in e nal acous ic mea us we e measu ed using he abo e- e e enced so wa e. 2.3. MDCT imaging Toshiba (Aquilion ONE™, Toshiba Medical Sys ems Co - po a ion, Tokyo, Japan) wi h 320- ow de ec o was used o acqui e iso opic olumes o en i e empo al bone including bo h sides in a pa ien suspec ed o es ibula pa oxysmia on axial o ien a ion. The ollowing pa ame e s we e used: ol age 135 kV, cu en 400 mA, FOV 24.0 cm, slice hickness 0.412 mm, magni ica ion ac o 1.00, and ma ix 512 512. The desi ed s uc u es we e demons a ed using mul iplana mode. Fig. 3. Impo an landma ks o he acial ne e canal in he empo al bone shown by a no el high- esolu ion CBCT sys em. The a ge s uc u es we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes o cone-beam p ojec ions on axial axis o a le empo al bone(AeD). BB: Bill's ba ; ChT: cho da ympani; CP: cochlea i o m p ocess; EC: elec ode con ac ; ET: Eus achian ube; G-FN: geniculum o he acial ne e; Inc: incus; LS-FN: laby in h segmen o he acial ne e; Ma: malleus; MF: mea us o amen; MS-FN: mas oid segmen o he acial ne e; SCTTM: semicanal o he enso ympani muscle; SF: s ylomas oid o amen; SP: s yloid p ocess; TS-FN: ympanic segmen o he acial ne e. Scale ba ¼5 mm. 11J. Zou e al. / Jou nal o O ology 12 (2017) 9e17 2.4. S a is ics The mean alues and s anda d de ia ion (SD) o he mea- su es we e calcula ed. 3. Resul s High-quali y empo al bone images we e acqui ed using he no el CBCT se -up in combina ion wi h he op imized imag- ing pa ame e s. In addi ion o he ossicula chain, he ine s uc u es o he middle ea , including he ympanic mem- b ane, he endon o he enso ympani, he cochlea i o m p ocess o he semicanal o he enso ympani, he py amidal eminence, and he oo pla e o he s apes, we e clea ly demons a ed (Fig. 2). Al hough he MDCT clea ly displayed he ossicula chain and he ine a chi ec u es o s apes, he esolu ion was signi ican ly lowe han ha acqui ed using he cu en CBCT sys em (Fig. 2). The laby in hine, ympanic, and mas oid segmen s o he acial ne e we e demons a ed wi h high esolu ion (Fig. 3). The cochlea i o m p ocess o he enso ympani was always iden i ied as a landma k o loca e he s a ing poin o he ympanic segmen o he acial ne e (Fig. 4). The sho es dis ance be ween he cochlea i o m p ocess and he ympanic segmen o he acial ne e was 0.5 ±0.2 mm (mean ±SD) (Table 1). The g ea e supe icial pe osal ne e ha o igina es om he geniculum o he acial ne e was also iden i ied (Fig. 5). The na owes si e o he mea al o amen measu ed 0.9 ±0.3 mm (mean ±SD, Table 1). The semici cula canals we e illus a ed wi h high accu- acy, and he sup alaby in hine space was clea ly demons a ed (Fig. 6). Among he sup alaby in hine space (ai cell ac ), pos e osupe io , pos e omedial, suba cua e, and an e io ac s we e isualized in se e al empo al bones. The pos e omedial and suba cua e ac s we e de ec ed in all he 6 empo al bones. The pos e osupe io ac s appea ed in 5/6 empo al bones. The an e io sup alaby in hine ac s we e iden i ied in 2/6 empo al bones. The pos e io semici cula wall exhibi ed he g ea es a iabili y wi h espec o hickness. The la e al semici cula canal wall was he hinnes ollowed by he su- pe io semici cula canal wall, while he pos e io semici cula canal wall was he hickes (Table 1). The pa hway o he suba cua e canal was also delinea ed by he suba cua e ossa o he mas oid an um, and he accompanying suba cua e ai cells we e easily dis inguished om he suba cua e (Fig. 7). The es ibula aqueduc , which is he ines canal in he empo al bone, was ollowed om he o igin in he u icle and saccule o he opening in he pos e io ossa (ope cula poin ), which hos s he endolympha ic sac (Fig. 8). The es ibula aqueduc has a midpoin wid h o 0.4 ±0.0 mm and ope cula wid h o 0.5 ±0.1 mm (mean ±SD, Table 1). The leng h o he in e nal acous ic mea us exhibi ed he g ea es a iabili y among all o he c i ical measu es o he empo al bone, and i s alue was 10.6 ±1.2 mm (mean ±SD), while he diame e o he in e nal acous ic mea us exhibi ed a smalle a iabili y and a alue o 3.7 ±0.3 mm (mean ±SD, Fig. 9,Table 1). 4. Discussion The p esen wo k demons a ed ha a no el high- esolu ion CBCT sys em was able o illus a e he ine ana omy o human empo al bones. Rega ding he acial ne e, he ull cou se wi hin he empo al bone was isualized, and all o he c i ical landma ks we e consis en ly iden i ied. Visualiza ion o he mea us o amen and geniculum o he acial ne e is ele an o he diagnosis o Bell's palsy and help ul o he Table 1 Measu es o he c i ical s uc u es o he human empo al bones using he no el CBCT sys em. S uc u es n Mean (mm) SD IAM-D 6 3.7 0.3 IAM-L 6 10.6 1.2 FNMF-D 6 0.9 0.3 FNCP-D 6 0.5 0.2 SSCC-W 6 0.8 0.1 PSCC-W 6 1.9 0.6 LSCC-W 6 0.7 0.1 VAM 6 0.4 0.0 VAO 6 0.5 0.1 IAM-D: diame e o he in e nal acous ic mea us; IAM-L: leng h o in e nal acous ic mea us; FNMF-D: diame e o he acial ne e canal a he si e o he mea al o amen; SSCC-W: wall o he supe io semici cula canal; PSCC-W: wall o he pos e io semici cula canal; LSCC-W: wall o he la e al semi- ci cula canal; VAM: es ibula aqueduc midpoin ; VAO: es ibula aqueduc ope culum; FNCP-D: dis ance be ween he cochlea i o m p ocess and ym- panic segmen o he acial ne e. Fig. 4. Spa ial associa ion be ween he cochlea i o m p ocess and he ympanic segmen o he acial ne e demons a ed by he no el high- esolu ion CBCT sys em. The a ge s uc u es we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes o cone-beam p ojec ions on axial axis o ei he le (A, B, C, and E) o igh (D, F) empo al bones. CP: cochlea i o m p ocess; FN: acial ne e. Scale ba ¼5 mm. 12 J. Zou e al. / Jou nal o O ology 12 (2017) 9e17 co esponding su gical p ocedu e (Mu ai e al., 2013). Visu- aliza ions o he ine s uc u es o he g ea e supe icial pe osal ne e and he enso ympani a e ele an o su gical design o acial ne e decomp ession. The g ea e supe icial pe osal ne e is a landma k o he iden i ica ion o he geniculum o he acial ne e, which is he mos equen si e o ac u e in cases o empo al bone auma causing acial palsy (Raja i e al., 2014). The enso ympani app oach wi h Fig. 6. Semici cula canals and sup alaby in hine space demons a ed by CBCT. The a ge s uc u es we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes o cone-beam p ojec ions on axial axis o a le empo al bone (AeD). AT: an e io ac o sup alaby in hine space; LSCC: la e al semici cula canal; PMT: pos e omedial ac o sup alaby in hine space; PST: pos e osupe io sup alaby in hine space; PSCC: pos e io semi- ci cula canal; ST: suba cua e ac o sup alaby in hine space; SSCC: supe io semici cula canal. Scale ba ¼5 mm. Fig. 5. G ea e supe icial pe osal ne e demons a ed by he no el high- esolu ion CBCT sys em. The a ge s uc u es we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes o cone-beam p ojec ions on axial axis o a igh empo al bone (A, B). BB: Bill's ba ; CN: cochlea ne e; EC: elec ode con ac ; G-FN: geniculum o he acial ne e; GSPN: g ea e supe icial pe osal ne e; LSCC: la e al semici cula canal; LS-FN: laby in h segmen o he acial ne e; TS-FN: ympanic segmen o he acial ne e. Scale ba ¼3 mm. 13J. Zou e al. / Jou nal o O ology 12 (2017) 9e17 ex ended pos e io ympano omy can e en be used o emo e bony agmen s a he base o he genicula e ganglion (Jung e al., 2013). Using he no el high- esolu ion CBCT sys em, all o he semici cula canals we e clea ly isualized, and accu a e measu es we e ob ained. The pos e io semici cula canal has he hickes wall among he semici cula canals. The ull cou se o he suba cua e canal om he suba cua e ossa o he mas oid an um was isualized, and he accompanying sub- a cua e ai cells we e dis inguished om he suba cua e canal. I has been epo ed ha suba cua e enous mal o ma ions cause audio- es ibula symp oms simila o hose o SCCD (B an be g e al., 2004). The su icien demons a ion o he ull cou se o he es ibula aqueduc using he no el high- esolu ion CBCT p o ides a use ul ool o he diagnosis o enla ged es ibula aqueduc (EVA). EVA can be con i med by ei he CT o magne ic esonance imaging (MRI), and he o me is mos commonly used in he clinic because o he inne ea mal o ma ions can be de ec ed by CT wi h high e - icacy. I has been epo ed ha 45% o pa ien s wi h EVA ha e es ibula signs and symp oms (Zalewski e al., 2015). The e is an u gen need o use CBCT o de ec EVA in he clinic because his condi ion occu s in child en who a e ex emely sensi i e o he adia ion c ea ed by CT imaging. Supe io semici cula canal dehiscence (SSCD) was i s desc ibed in a epo om Mino e al., in 1998 based on CT imaging (Mino e al., 1998). In 2007, Zhou e al. epo ed a case o SSCD in a young child a he age o 12 yea s and sugges ed ha SSCD is a de elopmen al de ec . The co- exis ence o SSCD and EVA u he suppo ed his de elop- men al hypo hesis (Ma e al., 2009; Zhou e al., 2007). The p esen s udy e ealed ha he a e age wid h o es ibula aqueduc is 0.4 a midpoin and 0.5 a ope cula si e, which is a below he alue o EVA (Bos on e al., 2007). This no el sys em may also p o ide addi ional in o ma ion o aid he unde s anding o he congeni al e iology o Menie e's disease in associa ion wi h mal o ma ions o he es ibula aqueduc . In o ma ion abou he es ibula aqueduc mal o ma ion in Menie e's disease has been ob ained using CBCT imaging (Yamane e al., 2015). Accu a e measu es o he es ibula aqueduc using ou high- esolu ion CBCT will p o ide a eliable ool o in es iga ions o he po en ial pa hological changes in Menie e's disease. The sup alaby in hine space was de ec ed using MDCT and has clinical signi icance in he empo al bone d illing and explo a ion o he medial wall o he a ic o choles ea oma Fig. 7. Suba cua e canal demons a ed by he no el high- esolu ion CBCT sys em. The a ge s uc u es we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes o cone-beam p ojec ions on axial axis o ei he le (D) o igh (AeC) empo al bones. AC: ai cell; EC: elec ode con ac ; MA: mas oid an um; PSCC: pos e io semici cula canal; SAC: suba cua e canal; SAF: suba cua e ossa; SSCC: supe io semici cula canal;VA: es ibula aqueduc ; Ves : es ibule. Scale ba ¼5 mm. 14 J. Zou e al. / Jou nal o O ology 12 (2017) 9e17 emo al and acial ne e decomp ession (Glu h e al., 2011; Jiang e al., 2012; Ni e al., 2016; Yamakami e al., 2003). CBCT showed excellen pe o mance in de ec ing his egion and e ealed ha he an e io sup alaby in hine ai cells appea ed in equen ly in he empo al bones compa ing o he o he ai cells o he sup alaby in hine space. The high eso- lu ion images showing he sup alaby in hine space sugges ed ha he no el CBCT sys em is capable o de ec ing he cho- les ea oma occu ed in such insidious a ea in he empo al bone. X- ay mic o omog aphy (mCT) is capable o eaching a spa ial esolu ion o 1.7 mm, and displayed he s ia ascula is, spi al ligamen , Reissne 's memb ane, among o he s uc u es and e en e ealed a memb ane up u e wi hin he human co- chlea (Zou e al., 2015c). Using mCT, he dis ibu ion o ans ympanically injec ed sil e nanopa icles in he middle and inne ea o he a and hei anspo a ion pa hway ollowing injec ion we e isualized (Zou e al., 2015d). Howe e , i can only be used o Ex i o s udies due o he limi ed size o imaging pla e o m and ex emely high dose o adia ion (Zou e al., 2016). Accu a e 3-dimensional p in ing empo al bone models based on clinical CT scans was epo edly bene icial o p e- ope a i e simula ion o speci ic challenging o ologic cases in child en, po en ially educing medical e o s and imp o ing pa ien sa e y (Rose e al., 2015). I is ele an o acqui e images using he p esen no el CBCT sys em o educe he X- ay dosage while gua an eeing he high esolu ion o images. 3-dimensional p in ing empo al bone migh also be used o Fig. 8. Pa hway o he es ibula aqueduc demons a ed by he no el high- esolu ion CBCT sys em. The a ge s uc u es we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes o cone-beam p ojec ions on axial axis o ei he le (AeC) o igh (D) empo al bones. EC: elec ode con ac ; LAeVA: Longi udinal axis o ex e nal ape u e o he es ibula aqueduc ; MDP-VA: midpoin o es ibula aqueduc ; MP: mee ing poin o he es ibula aqueduc ; OS-VA: ope cula si e o es ibula aqueduc ; SaB: saccula b anch o he es ibula aqueduc ; S a: s apes; U B: u icula b anch o he es ibula aqueduc ; VA: es ibula aqueduc ; Ves : es ibule. Scale ba ¼5 mm. Fig. 9. Measu emen o he in e nal acous ic mea us on he CBCT image. The a ge s uc u es we e iden i ied by adjus ing he loca ion and o ien a ion o he axial, sagi al and co onal iewing planes o cone-beam p ojec ions on axial axis o a le empo al bone. EC: elec ode con ac ; D: diame e ; L: leng h; Mod: modiolus. Scale ba ¼5 mm. 15J. Zou e al. / Jou nal o O ology 12 (2017) 9e17 educa ional empo al bone aining and p e-ope a i e aining in o he challenging cases (Hochman e al., 2014, 2015; Mow y e al., 2015). The CBCT da a may also be used in i ual eali y empo al bone aining o he esiden s in he u u e (Ande sen e al., 2016a, 2016b). 5. Conclusions The no el high- esolu ion CBCT sys em was ound o be powe ul in he de ec ion o he ine middle ea and inne ea s uc u es and acial ne e pa hway wi hin he empo al bone. This sys em po en ially has b oad applica ions in he di- agnoses o inne ea diseases, he de ec ion o associa ed pa hological changes, su gical planning, na iga ion o he ea su ge y, and empo al bone aining. Howe e , he p esen wo k did no in end o p o ide no mal alues in he empo al bone due o he limi ed numbe o samples. Decla a ion o con lic ing in e es s The au ho s decla ed no po en ial con lic s o in e es wi h espec o he esea ch, au ho ship, and/o publica ion o his a icle. Funding This wo k was suppo ed by EC FP7 collabo a i e p ojec NANOCI (g an ag eemen numbe : 281056) and Na ional Na u al Science Founda ion o China (81170914/H1304). Re e ences Ande sen, S.A., Mikkelsen, P.T., Konge, L., Caye-Thomasen, P., So ensen, M.S., 2016a. 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