Advanced Imaging Techniques in Skull Base Osteomyelitis Due to Malignant Otitis Externa

Abstract

Purpose of ReviewTo give an up-to-date overview of the strengths and weaknesses of current imaging modalities in diagnosis and follow-up of skull base osteomyelitis (SBO).Recent FindingsCT and MRI are both used for anatomical imaging, and nuclear techniques aid in functional process imaging. Hybrid techniques PET-CT and PET-MRI are the newest modalities which combine imaging strengths.SummaryNo single modality is able to address the scope of SBO. A combination of functional and anatomical imaging is needed, in the case of newly suspected SBO we suggest the use of PET-MRI (T1, T2, T1-FS-GADO, DWI) and separate HRCT for diagnosis and follow-up.

99mTc‐HMPAO‐leukocyte scintigraphy for diagnosis and therapy monitoring of skull base osteomyelitis

“…However, MRI is unable to discriminate SBO from other differential diagnoses, especially tumor processes. Also, CT and MRI abnormalities persist despite the resolution of the disease, and so are not useful for therapeutic monitoring in SBO . Bone remineralization after disease resolution is a late phenomenon making CT not reliable for early therapeutical management .…”

“…Also, CT and MRI abnormalities persist despite the resolution of the disease, and so are not useful for therapeutic monitoring in SBO. 7,8 Bone remineralization after disease resolution is a late phenomenon making CT not reliable for early therapeutical management. 9,11,18 On MRI, soft tissue abnormalities also persist after the resolution of the disease, as well as bone marrow abnormal signals that persist from 6 to 12 months after successful treatment.…”

“…Various studies on SBO highlighted the need for a sensitive and specific technique that could help physician to affirm healing in order to adapt case by case the duration of antibiotherapy . The persistence of MRI and CT abnormalities after treatment despite resolution of the disease makes these techniques unreliable . Bone scintigraphy (HMDP‐Tc‐99m) has the same limitations .…”

“…6 The persistence of MRI and CT abnormalities after treatment despite resolution of the disease makes these techniques unreliable. [7][8][9][10][11] Bone scintigraphy (HMDP-Tc-99m) has the same limitations. 9 Leukocyte scintigraphy (LS) is known to specifically detect bacterial infections, but very few data are available regarding LS in SBO.…”

A review of thirty‐nine patients diagnosed with necrotising otitis externa over three years: Is CT imaging for diagnosis sufficient?

“…However, NOE does not always show osseous destruction in an early stage. 4 Obvious soft tissue swelling and loss of fat planes, for example, in the retrocondylar and parapharyngeal spaces, can be seen on CT; however, early soft tissue findings in NOE are poorly evaluated by CT and are difficult to appreciate. More often, the soft tissue findings simply are not visible on CT.…”