ALADA Dose Optimization in the Computed Tomography of the Temporal Bone: The Diagnostic Potential of Different Low-Dose CT Protocols

Objective: Repeated computed tomography (CT) is essential for diagnosis, surgical planning and follow-up in patients with middle and inner ear pathology. Dose reduction to “as low as diagnostically acceptable” (ALADA) is preferable but challenging. We aimed to compare the diagnostic quality of images of subtle temporal bone structures produced with low doses (LD) and reference protocols (RP). Methods: Two formalin-fixed human cadaver heads were scanned using a 64-slice CT scanner and cone-beam CT (CBCT). The protocols were: RP (120 kV, 250 mA, CTDIvol 83.72 mGy), LD1 (100 kV, 80 mA, CTDIvol 26.79 mGy), LD2 (100 kV, 35 mA, CTDIvol 7.66 mGy), LD3 (80 kV, 40 mA, CTDIvol 4.82 mGy), and CBCT standard protocol. Temporal bone structures were assessed using a 5-point scale. Results: A median score of ≥2 was achieved with protocols such as the tendons of m. tensor tympani (RP/LD1/LD2/CBCT) and m. stapedius (CBCT), the incudostapedial joint (RP/LD1/CBCT), the incudomalleolar joint (RP/LD1/LD2/CBCT), the stapes feet (RP/LD1/CBCT), the stapes head (RP/LD1/LD2/CBCT), the tympanic membrane (RP/LD1/LD2/CBCT), the lamina spiralis ossea (none), the chorda tympani (RP/LD1/CBCT), and the modiolus (RP/LD1/LD2/CBCT). Adaptive statistical iterative reconstructions did not show advantages over the filtered back projection. Conclusions: LD protocols using a CTDIvol of 7.66 mGy may be sufficient for the identification of temporal bone structures.

Ossiculoplasty for Malleus Bar with Incudostapedial Disconnection and Fused Incudomalleolar Joint

Malleus bar is an abnormal bony connection between the malleus handle and the posterior wall of the tympanic cavity. We report a patient with a malleus bar and another malformation of the ossicles. An 11-year-old boy presented with hearing impairment since early childhood. Computed tomography (CT) revealed a malleus bar with an incudostapedial disconnection in the right ear. At tympanoplasty, the malleus bar was first identified and removed. A fused malleus-incus, not visible on the preoperative CT, was found intraoperatively. Therefore, the fused malleus-incus was removed; then, the ossicular chain was reconstructed, resulting in an improved postoperative hearing level. On preoperative CT, the disconnected incudostapedial joint had been identified, whereas the fused malleus-incus had not. Given the variations in the malleus bar anomaly of the middle ear, the surgical procedure for ossiculoplasty should be adapted intraoperatively based on any findings not visible on the preoperative CT.

Long-term outcomes of ossiculoplasty using bone cement

ObjectiveThis study aimed to evaluate the long-term results of ossiculoplasty using bone cement.MethodForty patients (24 females and 16 males; mean age: 34.1 ± 11.8 years; range, 9–54 years) with chronic otitis media with perforation but without cholesteatoma who had undergone incudostapedial rebridging ossiculoplasty using bone cement were evaluated retrospectively. Pre-operative and post-operative audiograms were evaluated. Bone conduction, air conduction and air–bone gaps were calculated according to international guidelines.ResultsThere was a mean reduction in pre-operative and post-operative air conduction (12.30 ± 11.98 dB), and this result was significant (p = 0.0001). There was a mean reduction in pre-operative and post-operative bone conduction (4.30 ± 6.69 dB), and this result was significant (p < 0.0001). The pre-operative air–bone gap was 27.65 dB and decreased to 19.65 dB during follow-up (p = 0.0001). No adverse reactions or complications were observed.ConclusionBone cement is reliable for the repair of incudostapedial-joint defects.