3D Reconstruction Helps Explain Vertigo

Daily Bulletin coverage of RSNA 2013 is available at RSNA.org/bulletin.

Three-dimensional reconstruction of high-resolution MR imaging sequences can be used to measure volume in the vestibular system in patients with vertigo, and help explain the symptoms, according to research presented at RSNA 2013.

Vertigo is a common symptom in patients seeking medical help from ear, nose and throat physicians, said Nagy N. Naguib, M.Sc., of the Johann Wolfgang Goethe University Hospital in Frankfurt, Germany, and the Department of Radiology, Alexandria University in Alexandria, Egypt. In fact, according to Dr. Naguib, vertigo and headache account for two of the most common complaints of patients seeking medical help.

“While MRI is a useful tool in the evaluation of vertigo patients, there are still some cases that don’t show any detectable structural changes on MRI,” Dr. Naguib said. “We thought it would be helpful to assess the volume of the vestibular system as a part of patients’ evaluation for cases presenting with vertigo and referred to radiologists for MR imaging assessment.”

The research began as an attempt to make use of the available software and available resolution delivered by MR imaging in order to obtain a 3D reconstruction of the inner ear structures. The aim of these reconstructions was to provide the reading radiologist and referring clinician with an easy way to evaluate 3D images of the inner ear structures, which are located in the three planes and have a complex anatomy, Dr. Naguib said.

In performing the reconstructions, Dr. Naguib and colleagues noticed that in certain cases, some of the semicircular canals seemed to be interrupted, were absent or looked thinner than usual. While some of these structural differences—such as a missing semicircular canal—are easily evaluated, others require more experienced readers.

“Based on this we tried to assess all cases with an objective method of measurement—namely the volumetric assessment of the 3D figure obtained,” Dr. Naguib said. “The sequence used for the reconstruction is already integrated in many of the examination protocols for the inner ear, and the new application of this routinely performed sequence represents the core of the current research.”

Dr. Naguib and colleagues retrospectively studied 153 patients with a mean age of 48.9 years, 61 of whom presented with vertigo and 92 of whom presented with other diseases of the ear and normal vestibular function. In patients with vertigo, the mean volume of the semicircular canals was 0.258 cm3 and the mean volume of the vestibule was 0.069 cm3. In patients without vertigo, the mean volume of the semicircular canals was 0.306 cm3 and the mean volume of the vestibule was 0.075 cm3.

Researchers concluded that the reduced volume of the vestibular system in patients presenting with vertigo could account for their symptoms.

Dr. Naguib pointed out that most studies addressing the subject in the past have relied on assessing the bony part of the inner ear using CT and that this method—while beneficial—does not accurately reflect the status of the contents of the bony cavities.

In addition, use of 3D reconstructions can be more than just a tool to impress other clinicians, Dr. Naguib said. “We think adding 3D reconstructions might open the horizon for other studies addressing the subject of inner ear pathology in general, and the subject of vertigo in particular. It’s important to have the ability to assess the structural changes in an objective way that might be associated with vertigo rather than relying only on the subjective experience of the reader.”

Medical Ozone Improves Condition of Patients with Herniated Disks

Daily Bulletin coverage of RSNA 2013 is available at RSNA.org/bulletin.

Medical ozone injections improve symptoms in almost 75 percent of patients with herniated disks in their lower backs, according to new research presented at RSNA 2013.

Ozone is a structurally modified form of oxygen present in small amounts in the atmosphere. Research has shown that it has a destructive effect on substances called proteoglycans that make up a major component of the nucleus pulposus, the jelly-like substance in the middle of a spinal disk. The nucleus pulposus can be forced out of the disk, exerting pressure on the nerve located nearby, leading to sciatica.

“The water-binding capacity of the proteoglycans is the main force that holds water to the nucleus pulposus,” said study author Thomas Lehnert, M.D., from the Department of Diagnostic and Interventional Radiology at the Goethe University in Frankfurt, Germany. “Destruction of the proteoglycans reduces the hold water and therefore diminishes the size of herniation.”

Ozone also has an effect on disk inflammation by altering the breakdown of arachidonic acid, a fatty acid found in tissues, to inflammatory prostaglandins. “Therefore, by reducing the inflammatory components, there is a corresponding reduction of pain,” Dr. Lehnert said.

Dr. Lehnert and colleagues recently evaluated the effects of ozone on 371 patients with lumbar radiculopathy, a condition in which compressed nerves in the spine cause pain and numbness.

Patients received one injection of a mixture of 97 percent oxygen and 3 percent ozone into the disk, and another perianglionically, or around a mass of ganglion nerve cells. The ozone injections were performed under CT guidance and followed by corticosteroid and anesthetic injections in the same session.

The researchers assessed clinical outcomes six months after treatment and used MR imaging to evaluate disk matrix and disk volume. Treatment was successful in 268 patients, or slightly more than 72 percent. Among those patients, outcome was excellent in 133 patients (49.6 percent) and good in the remaining 135 patients.

“The ozone did not cause any complications in patients,” Dr. Lehnert said.

MR imaging findings revealed that the majority of patients had a statistically significant reduction of volume in their herniated lumbar disks. On average, patients with excellent outcomes experienced a 20 percent reduction in disk volume, while those with good outcomes had a 7 percent volume reduction.

This volume-reduction effect correlated negatively with the patient’s age and positively with initial disk volume.

“Our study shows that the combined intradiskal and periganglionic injection of medical ozone and periganglionic injection of steroids affects both the mechanical and the inflammatory components of pain caused by disk herniation,” Dr. Lehnert said. “For this reason, oxygen-ozone injections are a therapy option for treating lumbar disk herniation that has failed to respond to conservative management, before recourse to surgery or when surgery is not possible.”

The ease of execution and noninvasiveness of medical ozone therapy make it a potentially useful tool for outpatient procedures, Dr. Lehnert said. Because of its toxicity, medical ozone is currently approved only for research purposes in Europe and the U.S., though Dr. Lehnert added that approval for clinical use may be only a few years away.