Secondary post-traumatic enophthalmos: high-resolution magnetic resonance imaging compared with multislice computed tomography in postoperative orbital volume measurement.
OBJECTIVE
Multislice computed tomography (MSCT) was the modality of choice for orbital volume measurement. This first prospective study compares MSCT with high-resolution magnetic resonance imaging (MRI) combined with micro (MRImc) and headcoil (MRIhc) in volumetric evaluation of the postsurgical enophthalmic orbit.


METHODS
Morphologic and dimensional changes of the orbit, eyebulb, and fat content were investigated 3 to 4 months after reconstruction of complex orbital fractures in 36 patients. Image analysis and volumetric assessment from 2-dimensional and 3-dimensional-MRImc and MRIhc were compared with MSCT. The volume segmentation algorithm operated on multispectral, 3-dimensional MR data acquired at isotropic proton density weighted acquisitions.


RESULTS
CT and MRI volume data correlated significantly (P < .01). Enlargement of the posterior segment often resulted in orbital geometry change from conical to convex. Even cases of correct orbital reconstruction presented significant volume enlargement compared to the contralateral side (P < .01). The retro bulbar fat showed itself fragmented and was dislocated in the medial posterior region mostly. We found reduced sagittal eye projection, increased width of the orbital rim, and dislocation of the posteromedial orbital floor (P < .01). High correlation was detected between orbital volume increment and degree of enophthalmos (0.93 mm per 1 cm3 orbital volume enlargement diameter) (P < .01).


CONCLUSIONS
As MRI orbital volume measurement permitted prediction of postsurgical enophthalmos, which is related to possible failure in orbital volume correction and reduction of the posterior medial bulge and not to fat content changes, it is suited for planning secondary correction.
Kolk
Andreas
A
Department of Oral and Maxillofacial Surgery, University of Technology of Munich, Munich, Germany. andreas.kolk@gmx.de
Pautke
Christoph
C
Schott
Verena
V
Ventrella
Ester
E
Wiener
Edzard
E
Ploder
Oliver
O
Horch
Hans Henning
HH
Neff
Andreas
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002508:Cephalometry / Q000295:instrumentation*; D003936:Diagnosis, Computer-Assisted; D015841:Enophthalmos / Q000000981:diagnostic imaging* / Q000209:etiology / Q000601:surgery; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009915:Orbit / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D009917:Orbital Fractures / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery; D009929:Organ Size; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed