The pre-imaging evaluation of a patient consists of a detailed history, looking for hearing loss, vertigo, headaches, and a medical examination including a neuro-otologic and audiologic evaluation.

There is a wide variation in the reported incidence of structural abnormalities in patients with PT ranging from 44 to 91 % (Madani and Connors 2009). Diagnostic imaging, even performed optimally, fails to find a reason for PT in many patients (Verbist et al. 2011). If an intratympanic mass is seen at otoscopy, then the imaging analysis can start with a CT, thin sections with bone algorithm in the axial and coronal plane, of the temporal bone and adjacent structures of the skull base. The anatomy of the carotid canal and the jugular foramen is carefully studied. For the anatomical vascular variants and small soft tissue masses, like a small glomus tympanicum no further study is needed. For larger masses, an MRI examination is complementary and the CT study can be done without intravenous contrast. Various imaging strategies have been proposed for the investigation of PT in the otoscopically normal patient. Combined CT angiography (CTA) and CT venography (CTV) with a multidetector CT is a good approach for demonstrating arterial, venous, skull base and middle ear disease. MR and MR angiography cannot be trusted to confidently exclude all causes (Krishnan et al. 2006; Mattox and Hudgins 2008; Narvid et al. 2011; Verbist et al. 2011) (Table 2). Our protocol for the imaging analysis op PT consists of an CTA & CTV. The lower scan border is the level of vertebra cervical 7 and the upper border is the end of the skull. The lower border is chosen to include the carotid bifurcation in the protocol. The upper border is chosen for the detection of a possible high flow intracranial AVM, whereby the venous drainage is causing PT. Post-processing includes maximum intensity projections in the axial, coronal and sagittal planes. There are also separate multiplanar bony algorithm reconstructions of the right and left temporal bone with thin slices of 0.75 mm in the axial and coronal plane to detect an anatomical vascular variant or another intratemporal cause of the PT. For the detection of a dural arteriovenous fistula (DAVF) you have to look to: asymmetric arterial feeding vessels, “shaggy” appearance of a dural venous sinus, transcalvarial venous channels, asymmetric venous collaterals and abnormal size and number of cortical veins. The presence of asymmetrically visible and enlarged arterial feeders has a high sensitivity and specificity for the diagnosis of a DAVF (Fig. 1). A conventional digital subtraction angiography (DSA) is necessary in cases of a negative CTA, but a strong clinical suspicion and in the presence of vascular malformations to demonstrate the angioarchitecture and in case of endovascular treatment (Narvid et al. 2011).

Vascular anatomical variants of the temporal bone are a frequent cause of PT or a vascular retrotympanic mass that often clinically cannot be differentiated from a paraganglioma. This differentiation is important prior to biopsy or therapy. Often these variants are an incidental asymptomatic finding on a CT done for other reasons (Table 3). The radiological diagnosis is possible with MRI, MR angiography, and with CT. For some variants, like the dehiscent jugular bulb, the bone detail, available with CT is important. On MR spin echo sequences, the signal void of the abnormally located artery or vein may be identical to the signal void of the cortical bone and the air in the ear and the anomaly can be missed. A gradient echo sequence gives a high signal from the vessel with better differentiation from the cortical bone.