Neuroradiology Experts Provide Insight Into Otology Imaging

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Temporal bone and inner ear structures.

BOSTON—Hugh Curtin, MD, chief of radiology at Massachusetts Eye and Ear Infirmary in Boston, showed a slide presenting a long list of diagnoses that need to be considered in the case of a common problem, pulsatile tinnitus: Aberrant carotid, a glomus, arteriovenous fistula, pseudotumor cerebri, and arachnoid granulation were included, but the list went on.

While it’s certainly possible to run through all of these potential causes using imaging, it’s not ideal, making information from the ordering physician very useful in tailoring an imaging approach, Dr. Curtin said during a session focused on neuroradiological imaging in otologic disease, held at the Annual Meeting of the Triological Society in April, part of the Combined Otolaryngology Spring Meetings.

“Just a little bit of clinical information can be very helpful to us as radiologists,” he said. “The orders come in: Do you want to do MRV [magnetic resonance venography]? Do you want to do CT, CTA [computed tomography angiography]? What exactly do you want to do? If we know a little bit of the clinical information, it really does help guide us.”

Results of an otoscopy, for instance, are quite useful, he said. “If you have a normal otoscopy, then we’re going to go one way—but if it’s a red mass, CT, to look for these little plates of bone, is the way we tend to start,” he said. “If it’s a normal otoscopy, then we want to know if this is a pseudotumor cerebri candidate. These bits of information can save us a huge amount of time. To rule out everything, we would probably have to have several time slots on the MRI [magnetic resonance imaging], and it becomes a practical consideration.”

For most problems of the temporal bone, he said, imaging is generally started with CT, not MRI. “The only time we really start with MRI is when we’re looking for an acoustic neuroma, and indeed almost everything else is done with CT,” he said.

“The reason our first step is with CT is because we get such good bone detail—CT has very good density differences, contrast, the ability to visualize the small structures. This is really how we’ll evaluate anything that has a thin plate of bone or just a small bony structure that we may want to look at.”

Magnetic resonance is the best imging method when looking at subtle differences in soft tissues, he added, but when it gets up to bone, the resolution of CT is supreme.