In these cases, imaging can be performed after peak arterial timing and can be obtained approximately 20 to 25 seconds after injection of intravenous (IV) contrast material. This allows for a single test with lower total radiation dose when compared to separate CTA and CT venography (CTV) examinations. Overlapping of vessels is not problematic, and it shows not only both arterial and venous anatomy and pathology adequately in this balanced phase but also the bony details of the temporal bone when reconstructed in thin bone window settings [1,11,12]. MR brain, when performed for temporal bone/skull base evaluation of tinnitus, is usually performed using specialized internal auditory canal (IAC) protocols, which include thin-section, heavily T2-weighted sequences to evaluate for vascular loops and small vestibular schwannomas. Volumetric postcontrast T1-weighted images are also increasingly becoming a part of this protocol, which has the added benefit of assessment of the transverse and sigmoid sinuses. Functional MRI in patients with tinnitus is still a research tool and is not used in routine applications [13,14]. Venous arterial spin-labeling technique has a high sensitivity and specificity for the presence of a dural arteriovenous fistula (dAVF), and the addition of spin-labeling increases confidence in the diagnosis of this entity on MRI [15]. Time-resolved gadolinium-enhanced MR angiography (MRA) is a technique which combines many factors like T1 shortening effect of gadolinium, digital subtraction technique, dynamic imaging, and parallel imaging to provide high temporal resolution MRA images. Use of intelligent k-space sampling technique can further improve the spatial and temporal resolution. The rapid acquisition of multiple 3-D volumes with high temporal and spatial resolution renders excellent depiction of the vessels to detect dAVFs [16-18]. OR Discussion of Procedures by Variant Variant 1: Pulsatile tinnitus, unilateral or bilateral; no retrotympanic lesion on otoscopy. Initial imaging.
Tinnitus. In these cases, imaging can be performed after peak arterial timing and can be obtained approximately 20 to 25 seconds after injection of intravenous (IV) contrast material. This allows for a single test with lower total radiation dose when compared to separate CTA and CT venography (CTV) examinations. Overlapping of vessels is not problematic, and it shows not only both arterial and venous anatomy and pathology adequately in this balanced phase but also the bony details of the temporal bone when reconstructed in thin bone window settings [1,11,12]. MR brain, when performed for temporal bone/skull base evaluation of tinnitus, is usually performed using specialized internal auditory canal (IAC) protocols, which include thin-section, heavily T2-weighted sequences to evaluate for vascular loops and small vestibular schwannomas. Volumetric postcontrast T1-weighted images are also increasingly becoming a part of this protocol, which has the added benefit of assessment of the transverse and sigmoid sinuses. Functional MRI in patients with tinnitus is still a research tool and is not used in routine applications [13,14]. Venous arterial spin-labeling technique has a high sensitivity and specificity for the presence of a dural arteriovenous fistula (dAVF), and the addition of spin-labeling increases confidence in the diagnosis of this entity on MRI [15]. Time-resolved gadolinium-enhanced MR angiography (MRA) is a technique which combines many factors like T1 shortening effect of gadolinium, digital subtraction technique, dynamic imaging, and parallel imaging to provide high temporal resolution MRA images. Use of intelligent k-space sampling technique can further improve the spatial and temporal resolution. The rapid acquisition of multiple 3-D volumes with high temporal and spatial resolution renders excellent depiction of the vessels to detect dAVFs [16-18]. OR Discussion of Procedures by Variant Variant 1: Pulsatile tinnitus, unilateral or bilateral; no retrotympanic lesion on otoscopy. Initial imaging.