To evaluate three-dimensional volume-rendering of congenital inner-ear malfornations using the MR CISS (Constructive Interference in Steady State) sequence.

MR CISS images of 30 inner ears of 15 patients (M:F=10:5; mean age, 6.5years) in whom inner-ear malfornation was suspected were obtained using a superconducting Magnetom Vision System (Simens, Erlangen, Germany), with TR/TE/FA parameters of 12.25 ms/5.9 ms/70 degree. The images obtained were processed by means of the volume rendering technique at an advanced workstation (Voxtol 3.0.0; GE Systems, advanced workstation, volume analysis). The cochlea and three semicircular canals were morphologically evaluated.

Volume-rendered images of 25 inner ears of 13 patients demonstrated cochlear anomalies in the form of incomplete partition (n=18), hypoplasia (n=2), and severe hypoplasia (n=5). For the superior semicircular canal, findings were normal in 15 ears, though common crus aplasia (n=6), hypoplasia (n=4), aplasia (n=3), and a short and broad shape (n=2) were also observed. The posterior semicircular canal of 13 ears was normal, but common crus aplasia (n=6), a short and broad shape (n=5), aplasia (n=4), hypoplasia (n=3) were also identified. Twelve lateral semicircular canals, were normal, but other images depicted a short and broad shape (n=7), a dilated crus (n=5), a broad shape (n=4), and aplasia (n=2). In 14 patients the anomalies were bilateral, and in seven, the same anomalies affected both ears.

Three-dimensional volume rendering images of the inner ear depicted various morphological abnormalities of the cochlea and semicircular canals. At that locations, anomalies were more complicated and varied than in the cochlea. Three-dimensional volume rendering imaging using the MR CISS technique provides anatomical information regarding the membranous labyrinth, and we consider this useful in the evaluation of congenital inner ear malformations.