Indications for Orbital Imaging by the Oculoplastic Surgeon

Imaging of the Postoperative Orbit

Imaging evaluation of the postoperative orbit remains challenging even for the expert neuroradiologist. This article provides a simplified framework for understanding the complex postoperative appearances of the orbit, in an attempt to enhance the diagnostic accuracy of postoperative computed tomography and MR imaging of the orbit. Readers are familiarized with the normal appearances of common eye procedures and orbit reconstructions to help avoid interpretative pitfalls. Also reviewed are imaging features of common surgical complications, and evaluation of residual/recurrent neoplasm in the setting of oncologic imaging surveillance.

Pitfalls of ophthalmic radiographic imaging

PURPOSE OF REVIEW

Ophthalmologists are dependent on computed tomography (CT) and MRI to aid in the diagnosis and management of patients with orbital and visual conditions. Pitfalls in the imaging process can lead to inefficient care or patient harm. This review summarizes these problems and provides methods to reduce imaging errors.

RECENT FINDINGS

There has been exponential growth in the number of radiographic scans performed, resulting in increased awareness of the risks from medical radiation. Strategies to minimize radiation exposure include reducing the need for sequential scans, using appropriate technology, and substituting MRI for CT. Contrast administration can be associated with systemic reactions, renal disease, and thyroid dysfunction. Scan interpretation errors are reduced by the ophthalmologist reviewing the study and communication with the radiologist.

SUMMARY

Medical radiation exposure can be reduced by initially ordering the appropriate scan and substituting MRI for CT when possible. MRI is contraindicated in patients with certain implants and metallic foreign bodies. Noncontrast studies are adequate to evaluate many conditions and some patients should not receive contrast. Imaging errors can be reduced by the ophthalmologist personally reviewing the orbital scans and correlating the results with the clinical findings.

Update on imaging techniques in oculoplastics

Imaging is a beneficial aid to the oculoplastic surgeon especially in orbital and lacrimal disorders when the pathology is not visible from outside. It is a powerful tool that may be benefited in not only diagnosis but also management and follow-up. The most common imaging modalities required are CT and MRI, with CT being more frequently ordered by oculoplastic surgeons. Improvements in technology enabled the acquisition times to shorten incredibly. Radiologists can now obtain images with superb resolution, and isolate the site and tissue of interest from other structures with special techniques. Better contrast agents and 3D imaging capabilities make complicated cases easier to identify. Color Doppler imaging is becoming more popular both for research and clinical purposes. Magnetic resonance angiography (MRA) added so much to the vascular system imaging recently. Although angiography is still the gold standard, new software and techniques rendered MRA as valuable as angiography in most circumstances. Stereotactic navigation, although in use for a long time, recently became the focus of interest for the oculoplastic surgeon especially in orbital decompressions. Improvements in radiology and nuclear medicine techniques of lacrimal drainage system imaging provided more detailed analysis of the system.