Fat-suppressed MR of the orbit and cavernous sinus: comparison of fast spin-echo and conventional spin-echo.
OBJECTIVE
To compare T2-weighted fat-suppressed fast spin-echo imaging with fat-suppressed conventional spin-echo imaging in the detection of normal intraorbital and pericavernous anatomy and orbital disease, and to determine the efficacy of fat saturation with T2-weighted fast spin-echo imaging of the cavernous sinus.


METHODS
Contrast-to-noise ratios of normal intraorbital anatomy were calculated and compared in 10 consecutive patients using fat-suppressed fast spin-echo and conventional spin-echo T2-weighted images. Contrast-to-noise ratios of common intraorbital lesions were calculated and compared using fat-suppressed fast spin-echo and fat-suppressed conventional spin-echo. Qualitative evaluation was performed and compared for normal intraorbital anatomy using both fat-suppressed fast spin-echo and fat-suppressed conventional spin-echo in 16 patients. Qualitative evaluation for the detection of normal anatomic structures of the pericavernous region was performed and compared using fast spin-echo with and without fat suppression and fat-suppressed conventional spin-echo T2-weighted images in 16 patients. Fat saturation was performed using standard commercially available chemical saturation technique.


RESULTS
Reduced imaging time allowed more acquisitions for fat-suppressed fast spin-echo images, which significantly improved visibility of intraorbital and pericavernous anatomy over fat-suppressed conventional spin-echo. Anatomic visibility was also improved because of reduced motion, phase encoding, and susceptibility artifacts. There was no significant difference between contrast-to-noise ratios for fat-suppressed fast spin-echo and fat-suppressed conventional spin-echo imaging of the lateral and medial rectus muscles. Contrast-to-noise ratios of fat suppressed fast spin-echo of orbital disease was significantly greater than contrast-to-noise ratios of fat-suppressed conventional spin-echo. Detection of several normal anatomic structures of the pericavernous region was significantly improved with non-fat-suppressed fast spin-echo over fat-suppressed fast spin-echo because of significantly reduced magnetic susceptibility artifact.


CONCLUSIONS
Fat-suppressed fast spin-echo is superior to fat-suppressed conventional spin-echo for T2-weighted orbital imaging. Non-fat-suppressed fast spin-echo is the preferred pulse sequence for T2-weighted imaging of the cavernous sinus because of the minimal susceptibility artifact.
Mukherji
S K
SK
Department of Radiology, University of Florida College of Medicine, Gainesville 32610.
Tart
R P
RP
Fitzsimmons
J
J
Belden
C
C
McGorray
S
S
Guy
J
J
Mancuso
A A
AA
D000273:Adipose Tissue / Q000473:pathology; D016477:Artifacts; D002426:Cavernous Sinus / Q000473:pathology*; D003390:Cranial Nerve Neoplasms / Q000175:diagnosis; D003937:Diagnosis, Differential; D005910:Glioma / Q000175:diagnosis; D014890:Granulomatosis with Polyangiitis / Q000175:diagnosis; D006391:Hemangioma / Q000175:diagnosis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008577:Meningeal Neoplasms / Q000175:diagnosis; D008579:Meningioma / Q000175:diagnosis; D009901:Optic Nerve Diseases / Q000175:diagnosis; D009902:Optic Neuritis / Q000175:diagnosis; D009916:Orbital Diseases / Q000175:diagnosis*; D009918:Orbital Neoplasms / Q000175:diagnosis*; D012016:Reference Values