February has been designated Sinus Pain Awareness Month, and the 35 million people in the U.S. who suffer from sinusitis are still looking to breathe easy.
Sinusitis is more widespread than either arthritis or hypertension, according to the American Academy of Otolaryngology in Alexandria, VA. The academy's most recent figures have 475,000 people undergoing outpatient procedures annually to correct sinus problems. Imaging, not surprisingly, plays a major role in assessing these patients.
Researchers at Vanderbilt University in Nashville recently completed the first prospective study correlating a patient's sinus symptoms with CT findings. The 304 patients included in the study, which was conducted between March and September of 1998, were assessed for seven symptoms of sinusitis.
The severity of five symptoms -- fatigue, lack of sleep, nasal discharge, stuffy nose and decreased sense of smell -- correlated with the CT display of symptoms, the team found. But the severity of headache and facial pain had no correlation with the results of the scan. CT signs of sinusitis include mucosal hyperplasia, bone lesion, fluid retention and bullous concha.
The researchers concluded that if only facial pain and headaches are present, a CT scan could eliminate sinusitis as the culprit, as well as curb misdiagnosis and unnecessary referrals to ear, nose and throat specialists.
"The real problem that you have as an (ear, nose and throat practitioner) is that people come into your office complaining of headaches. Most headaches have nothing to do with sinusitis," said Dr. Berkley Eichel, a retired otolaryngologist in Torrance, CA.
Eichel developed a staging system for rhinosinusitis based on CT to discriminate between patients who require surgery and those who would benefit from a more conservative treatment plan (Ear, Nose & Throat Journal, 1999 April, Vol.78, No.4, pp.262-268).
"When the rare patient shows up with a headache that's secondary to sinusitis, there might be other serious complications going on. You can't really tell without imaging," Eichel said. In the rhinosinusitis staging system, he suggested the use of short-term oral corticosteroid therapy for the management of paranasal sinus problems, rather than endoscopy. Part of that treatment protocol would be frequent monitoring with CT.
CT has become the accepted modality for paranasal sinus imaging because of its ability to delineate anatomic structure and detect abnormalities, such as intranasal polyps. However, one drawback of CT is the potentially high radiation dose, which has inspired researchers to look at low-dose CT.
According to one 1991 study, CT examinations of the paranasal sinuses were routinely performed with 2 to 5-mm thick sections at 120 kVp and 300 to 400 mAs in the coronal and axial planes. (Neuroradiology 1991; Vol. 33, No. 5, pp.403-406). Researchers at the University Hospital in Lausanne, Switzerland compared images taken at 130 mA-3s, 60 mA-3s, 30 mA-3s and 30 mA-2s. They found the lower mAs settings did not affect the diagnoses or the delineation of abnormalities.
More recently, British researchers presenting at the 1999 RSNA meeting evaluated the use of CT scanning at 150, 100 and 50 mAs compared with their defined standard protocol of 200 mAs. They found no statistically significant difference between the four groups in demonstration of features on CT.
Other researchers from Israel compared conventional coronal helical scans with parameters that included slice thickness of 3.2 mm at 200 mAs to axial scans at 25 mAs and slice thickness of 1.3 mm that were coronally reconstructed. The very low dose, high-resolution, thin-section CT "markedly improved osseous anatomic resolution and increased patient comfort with a six-fold reduction in radiation dose," the researchers concluded.
German researchers also presented the results of a study comparing low-dose CT with conventional radiography at the 1999 RSNA meeting. Forty-three patients underwent low-dose CT, performed with 4-mm slices at 120 kVp and 50 mAs. In all but one of 22 patients, low-dose CT showed a wider range of symptoms than conventional radiography.
By Shalmali Pal
AuntMinnie.com staff writer
February 3, 2000
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