Radiology MRI

When looking at the contents of the Internal Acoustic Canal it always reminds me of a face of the " Monkey Looking at Cerebellum ". So I developed a simple way to remember its contents. Note the position of the oblique sagittal T2 slice that is indicated on the topogram and its angle that is shown on the right. You recognize cerebellum easily on the left image. Long arrow on the first image shows Vestibular Nerve entering Internal Acoustic Meatus. Oblique sagittal T2 sequence through the Internal Acoustic Canal showing it's contents: 02:00 - Superior Vestibular Nerve 04:00 - Inferior Vestibular Nerve 08:00 - Cochlear Nerve 10:00 - Facial Nerve. In other words the "mouth" of our "monkey" has a V letter shape since it is a "smiling monkey" and V represents Vestibular Nerve (Superior and Inferior). The upper "eye" is the Facial Nerve and the lower "eye" is the Cochlear Nerve. We can follow the Cochlear Nerve to the Coch

Note horizontal fracture Le Fort Type 1 involving maxillary sinus walls bilateraly. This type of the fracture causes instability of the alveolar process of the maxilla. Note fractured maxillary sinus walls, pterygoid process, blood levels in both maxillary sinus and extensive soft tissue emphysema. Le Fort fractures are divided in levels: Type 1 - below nose, Type 2 - above nose, Type 3 - through the orbits. Above schema is from Wikipedia that nicely presents types of Le Fort fractures.

This is a standard radiation dose report generated by GE LightSpeed 64-slice CT scanner. This is a report of the CT Angiography including native CT Brain scan followed by CT Angiography of the Head and Neck. Values presented in this report are: CTDI - CT Dose Index and DLP - Dose Length Product. Some physics: The CTDI represents the radiation dose of a single CT slice and is determined using acrylic phantoms. The weighted CTDI (CTDIw) reflects the weighted sum of two thirds peripheral dose and one third central dose in a 100-mm range in acrylic phantoms. The volume CTDI (CTDIvol), defined as CTDIw divided by the beam pitch factor, is the most commonly cited index for modern MDCT equipment. The dose length product (DLP) is the CTDIvol multiplied by the scan length (slice thickness × number of slices) in centimeters. DLP is independent of what is being scanned. So it is the same for a little child as for a large adult. It is possible, but difficult, to estimate the effective dose equiv

Native CT (without contrast) shows increased density in the right sigmoid sinus and transverse sinus. Those are not characteristic findings since also high RBC count can cause hyperdense sinus. However in this case note difference in density when compared with the normal left side. This is a sign that should raise suspicion of Cerebral Venous Sinus Thrombosis. Finding of Cerebral Venous Sinus Thrombosis is confirmed with CT Cerebral Venography that is performed 45 seconds after contrast injection. Above images show lack of contrast in the right sigmoid sinus (arrows) that is known as "empty delta sign". Also note large thrombus in the right transverse sinus (arrow heads). The "empty delta sign" mostly refers to lack of contrast in the confluence of sinuses but in this case it is the same principle and same empty delta in the sigmoid sinus. Most important take home message is to adjust the window and level on the native series and compare both sides for any asymmet

Patient resents with left sided pulsatile tinnitus. CTA reveals pathologically increased arterial circulation of the Occipital Artery and Posterior Auricular Artery branches (arrows). Also noted is arterial contrast intensity in the left Sigmoid Sinus and Internal Jugular Vein (arrowheads). Finding is consistent with Dural Arteriovenous Fistula (DAVF) from the Occipital Artery circulation. Note increased size and number of the branches from the Occipital Artery circulation.