Near-infrared imaging of the sinuses: preliminary evaluation of a new technology for diagnosing maxillary sinusitis

Abstract

Diagnosing sinusitis remains a challenge for primary care physicians. There is a need for a simple, office-based technique to aid in the diagnosis of sinusitis without the cost and radiation risk of conventional radiologic imaging. We designed a low-cost near-infrared (NIR) device to transilluminate the maxillary sinuses. The use of NIR light allows for greater interrogation of deep-tissue structures as compared to visible light. NIR imaging of 21 patients was performed and compared with computed tomography (CT) scans. Individual maxillary sinuses were scored on a scale from 0 to 2 based on their degree of aeration present on CT and similarly based on the NIR signal penetration into the maxilla on NIR images. Our results showed that air-filled and fluid/tissue-filled spaces can be reasonably distinguished by their differing NIR signal penetration patterns, with average NIR imaging scores for fluid-filled maxillary sinuses (0.93+/-0.78, n=29) significantly lower than those for normal maxillary sinuses (1.62+/-0.57, n=13) (p=0.003). NIR imaging of the sinuses is a simple, safe, and cost-effective modality that can potentially aid in the diagnosis of sinusitis. Long-term, significant device refinement and large clinical trials will be needed to determine the diagnostic accuracy of this technique.

Figure 1

NIR transillumination light source device consisting of two rows of NIR light emitting diodes surrounded by an acrylic casing.

Figure 2

Schematic demonstrating NIR transillumination pattern scoring. Each patient’s maxillary sinus was scored on a 0-to-2 scale based on the degree of NIR light penetration into the sinus.

Figure 3

(a) NIR transillumination pattern of 33-year-old Caucasian female with no history of nasal problems with (b) corresponding CT scan revealing bilaterally aerated maxillary sinuses. Note the diffusely strong transillumination of midface structures with increased signal intensity along the infraorbital rim.

Figure 4

(a) NIR transillumination pattern of 54-year-old Asian male with a diagnosis of chronic bilateral maxillary sinusitis with (b) corresponding CT scan revealing significant bilateral mucosal thickening of maxillary sinuses. Note the relatively dim transillumination pattern with absence of NIR light penetration into the maxillary sinuses.

Figure 5

(a) NIR transillumination pattern of 51-year-old Caucasian male with a diagnosis of unilateral maxillary sinusitis with (b) corresponding CT scan revealing total opacification of right maxillary sinus. Although subtle, note the relatively dim transillumination pattern of the right midface regions as compared to left, with particularly diminished light penetration through the right infraorbital rim.

Figure 6

(a) Preoperative and (b) postoperative transillumination patterns taken from a 73-year-old Caucasian male who underwent surgery for chronic bilateral maxillary sinusitis. Note increased postoperative light penetration through maxillary sinuses with signal abutting infraorbital rim.

Figure 7

Average transillumination scores versus CT scores. Average transillumination scores for those maxillary sinuses that were totally (1.07±0.15; n=5) or partially opacified (0.90±0.85; n=24) were lower than those that were totally aerated (1.62±0.57; n=13).