High- resolution CT (HRCT) of the temporal bone can detect some other conditions that cause PT but do not always present as a vascular retrotympanic mass, such as otospongiosis, Paget disease, sigmoid sinus diverticulum and sigmoid sinus dehiscence, high-riding jugular bulb, and SSCD [39]. SSCD is a known cause of PT and other symptoms of peripheral vestibulopathy and is readily diagnosed on CT temporal bone [40,41]. SSWAs are known causes of PT and may be the most common identifiable causes in this group [25]. They are much more frequently seen on CT temporal bone in patients with PT compared with the general population and are a common and treatable cause of PT [19,26,27,42]. It can be readily diagnosed with either CT temporal bone or CTA/CTV of the head [19]. One study found that SSWA was seen in all patients with venous PT in addition to other venous abnormalities [43]. IV contrast is not necessary. CT temporal bone has a smaller field-of-view and a higher resolution to evaluate the temporal bone compared with CTA. Tinnitus Labyrinthine sequestrum is a very rare infective condition in which there is destruction of the inner ear structures and can cause tinnitus in addition to other symptoms. On CT, one may see erosion of the bony labyrinth. On MRI, there may be abnormal enhancement of the labyrinthine contents on the postcontrast images [44]. Slight modification from usual CTA bolus timing can allow for a balanced phase examination facilitating detection of both arterial and venous etiologies of PT in the head and neck. Therefore, it is the imaging modality of choice in patients with PT without a suspected retrotympanic lesion because it can show both arterial and venous pathologies in the head, skull base, and neck, in addition to the bony details of the temporal bone. Temporal bone anatomy is also well seen on thin bone window reconstructions, which cannot be assessed on MRA/MRI.
Tinnitus. High- resolution CT (HRCT) of the temporal bone can detect some other conditions that cause PT but do not always present as a vascular retrotympanic mass, such as otospongiosis, Paget disease, sigmoid sinus diverticulum and sigmoid sinus dehiscence, high-riding jugular bulb, and SSCD [39]. SSCD is a known cause of PT and other symptoms of peripheral vestibulopathy and is readily diagnosed on CT temporal bone [40,41]. SSWAs are known causes of PT and may be the most common identifiable causes in this group [25]. They are much more frequently seen on CT temporal bone in patients with PT compared with the general population and are a common and treatable cause of PT [19,26,27,42]. It can be readily diagnosed with either CT temporal bone or CTA/CTV of the head [19]. One study found that SSWA was seen in all patients with venous PT in addition to other venous abnormalities [43]. IV contrast is not necessary. CT temporal bone has a smaller field-of-view and a higher resolution to evaluate the temporal bone compared with CTA. Tinnitus Labyrinthine sequestrum is a very rare infective condition in which there is destruction of the inner ear structures and can cause tinnitus in addition to other symptoms. On CT, one may see erosion of the bony labyrinth. On MRI, there may be abnormal enhancement of the labyrinthine contents on the postcontrast images [44]. Slight modification from usual CTA bolus timing can allow for a balanced phase examination facilitating detection of both arterial and venous etiologies of PT in the head and neck. Therefore, it is the imaging modality of choice in patients with PT without a suspected retrotympanic lesion because it can show both arterial and venous pathologies in the head, skull base, and neck, in addition to the bony details of the temporal bone. Temporal bone anatomy is also well seen on thin bone window reconstructions, which cannot be assessed on MRA/MRI.