Maxillary Sinus
Your maxillary sinuses are the largest air-filled spaces in your face, located beneath your eyes in your cheekbones. When imaging shows abnormalities in these areas, it usually indicates infection, inflammation, or blockage. This guide explains what radiologists see on CT scans and MRIs of your maxillary sinus and what these findings mean for your health.
What Is the Maxillary Sinus
The pyramid-shaped maxillary sinus is the largest of the paranasal sinuses, located in the maxilla. These air-filled spaces sit beneath your eyes on both sides of your nose, within your cheekbones. They hold between 15 to 20 mL of air and play important roles in your breathing, voice resonance, and protecting your skull from injury.
Your maxillary sinuses connect to your nasal cavity through small openings called ostia. When these drainage pathways become blocked, problems can develop that show up clearly on medical imaging.
Why Doctors Order Maxillary Sinus Imaging
Doctors typically recommend sinus imaging when you have persistent symptoms that suggest sinus problems. Common reasons include chronic facial pain, recurring sinus infections, persistent nasal congestion, or when initial treatments have not been effective.
Persistent or progressive symptoms after medical therapy, in combination with CT evidence of paranasal sinus disease, should prompt referral to specialists for further evaluation.
CT Scan Imaging of Maxillary Sinus
What CT Scans Show Best
CT is the most reliable imaging technique for determining if the sinuses are obstructed. It is the best imaging modality for sinusitis. CT scans are good at showing the bone structures around your sinuses and can clearly identify blockages in drainage pathways. Bone window views provide excellent resolution and a good definition of the complete osteomeatal complex and other anatomic details that play a role in sinusitis.
CT Scan Process for Maxillary Sinus
For a CT scan of the sinuses, the patient is most commonly positioned lying flat on the back. The procedure is quick and painless. The actual CT scan takes less than a minute and the entire process is usually completed within 10 minutes.
What CT Findings Mean
CT scans can reveal several important findings in your maxillary sinus:
Mucosal Thickening: This appears as increased soft tissue lining the sinus walls. Mild thickening may be normal, but significant thickening often indicates inflammation or infection.
Fluid Levels: When fluid accumulates in the sinus, it creates distinct horizontal lines on CT images, suggesting acute sinusitis or blockage.
Complete Opacification: When the entire sinus appears white or gray instead of black (air-filled), this indicates the sinus is completely filled with fluid, mucus, or infected material.
Bone Changes: CT can show if chronic infection has affected the surrounding bone structures.
MRI Imaging of Maxillary Sinus
When MRI Is Used
MRI allows better differentiation of soft tissue structures within the sinuses. It is used occasionally in cases of suspected tumors or fungal sinusitis. While CT is usually the first choice for sinus imaging, MRI provides superior detail for certain conditions.
What MRI Shows Differently
MRI is superior to CT in separating thickened mucosa, retained secretions and retentions cysts. This makes MRI particularly valuable when doctors need to distinguish between different types of sinus problems.
On MRI images, different tissues and fluids appear in distinct patterns. Infected material, clear fluid, and thickened sinus lining each have characteristic appearances that help radiologists make accurate diagnoses.
Common Maxillary Sinus Findings on Imaging
Acute Sinusitis
Imaging findings of acute rhinosinusitis are non-specific and can be seen in a large number of asymptomatic patients. When acute sinusitis affects your maxillary sinus, imaging typically shows fluid accumulation, mucosal swelling, and sometimes air-fluid levels.
Chronic Sinusitis
Long-term inflammation creates different imaging patterns. These changes include mucosal thickening, retention cysts, retained secretions, inspissated secretions and dystrophic calcification. Chronic changes often appear more complex on both CT and MRI images.
Dental-Related Issues
The maxillary dentition should also be assessed as ~20% of maxillary sinus infections are odontogenic. Your upper teeth roots can extend close to or into the maxillary sinus, making dental infections a possible source of sinus problems.
Retention Cysts
Mucus retention cysts (MRCs) are benign lesions in the paranasal sinuses representing obstructed submucosal mucinous glands. These appear as smooth, round structures within the sinus and are often discovered incidentally during imaging for other reasons.
Serious Conditions
Sinonasal cancers are rare but when tumors do occur, imaging plays an important role in early detection and treatment planning.
Understanding Normal Variations
Not all imaging findings indicate disease. Many asymptomatic adults have abnormalities on sinus CT scans. Many people with minor upper respiratory tract infections also have abnormalities in CT scans of the sinuses. This means minor changes on your imaging may be completely normal.
Many studies using CT and MRI imaging confirmed the high prevalence of incidental sinus findings without initial clinical symptoms. Your radiologist and doctor consider these findings alongside your symptoms to determine if treatment is needed.
When Imaging Results Require Action
Findings on CT scan should be interpreted in conjunction with clinical and endoscopic findings because of high rates of false-positive findings. Your symptoms matter more than imaging findings alone when deciding on treatment.
Concerning findings that typically require follow-up include complete sinus blockage with symptoms, signs of spreading infection, bone destruction, or features suggesting tumors. If additional information is needed to determine the extent of soft tissue of the tumor, magnetic resonance imaging (MRI) may be helpful.
What Happens After Imaging
Most maxillary sinus problems respond well to medical treatment including antibiotics, decongestants, and anti-inflammatory medications. CT of the sinuses can help plan the safest and most effective surgery when surgical intervention becomes necessary.
Understanding your maxillary sinus imaging results helps you work effectively with your healthcare team to address any problems and maintain good sinus health. Remember that imaging provides valuable information, but your symptoms and overall health guide treatment decisions.
References:
- Radiological Imaging in the Management of Sinusitis – American Family Physician
- CT of the Sinuses – RadiologyInfo.org
- Paranasal Sinuses: Anatomy, Function & Types – Cleveland Clinic