Fundamental knowledge of head and neck anatomy and development, as well as an understanding of the strengths and weaknesses of CT and MR, can help radiologists accurately and confidently assess skull base lesions.
A Thursday afternoon education session moderated by Luke Ledbetter, MD, director of head and neck imaging and associate professor at the David Geffen School of Medicine at University of California, Los Angeles (UCLA) included a case-based review of imaging and clinical features that can help distinguish tumors from tumor mimics in the neck, skull base, brain and spine.
Dr. Ledbetter’s presentation focused on tumors and mimics located in the skull base. “The skull base is a challenging area to evaluate due to complex bones that serve as a barrier to the delicate intracranial compartment as well as multiple foramina, canals and fissures that act as the routes of travel between the intracranial and extracranial world,” he said.
Ledbetter
According to Dr. Ledbetter, a lack of understanding of the development of the skull base and a lack of having a well-focused differential diagnosis based on lesion location are two primary reasons clinicians may mistake mimics for actual tumors.
He said his diagnostic approach includes separating the anatomy into sections of – anterior, central, posterior or lateral – to help drive differential diagnosis.
Dr. Ledbetter also recommended knowing which examinations of the skull base provide the highest yield views and said inexperienced radiologists may not know which imaging plane is best to review specific areas of the skull base because of its 3D shape. Similarly, they may choose to evaluate a less-than-ideal imaging plane.
He noted that in the anterior skull base, coronal and saggital views are most helpful, in the central skull base, axial and saggital views provide the best look and in the posterior skull base, axial and coronal views are preferable.
Dr. Ledbetter also said that because of the complex structure of the skull base, which is made of both bones and soft tissues, many diagnoses require both CT and MR characterization to reach an accurate diagnosis. In these instances, trying to reach a diagnosis without using both modalities can lead radiologists in the wrong direction.
Considerations Beyond Imaging Can Assist with Diagnosis
Even experienced radiologists may also run into challenges differentiating lesions from mimics, and in those cases, Dr. Ledbetter said good clinical history or follow-up imaging are necessary for accurate characterization.
This advice was echoed by the other presenters in the education session who recommended thorough review of factors like age and clinical history, as well as structural concerns like obstruction or preservation of the architecture of surrounding features, when trying to differentiate between tumors and tumor mimics. In addition, the presenters emphasized the importance of consulting prior imaging studies, when possible, to arrive at a confident diagnosis.
“Through understanding the normal anatomy and very basic development concepts, radiologists will be better equipped to arrive at an accurate diagnosis and avoid unnecessary patient anxiety and invasive diagnostic procedures,” he said.
Access the presentation, “Case-based Review in Neuro and Head and Neck Imaging: Tumor or Tumor Mimic?” (R4-CHN07) at Meeting.RSNA.org.
