Imaging of the temporal bone.

A variety of congenital, infectious, inflammatory, vascular, and benign and malignant neoplastic pathology affects the temporal bone. Knowledge of normal temporal bone anatomy and space-specific differential diagnoses is key to imaging interpretation of temporal bone. Correlation with clinical history and physical examination is vital to making the correct diagnosis or providing an appropriate differential. Computed tomography and magnetic resonance imaging are complementary imaging modalities in the evaluation of temporal bone abnormalities.

Pineal region masses--imaging findings and surgical approaches.

The anatomy of the pineal region is complex. Despite advances in surgical techniques since the first reported successful pineal region surgery in the early 20th century, pineal region surgery remains challenging owing to the proximity of deep cerebral veins and dorsal midbrain structures critical for vision. In this article, we review the relevant surgical anatomy of the pineal region and discuss historically important and current surgical approaches. We describe specific imaging features of pineal region masses that may affect surgical planning and review neoplastic and nonneoplastic masses that occur in the pineal region.

Vascular and ureteral anatomy relative to the midsacral promontory.

OBJECTIVE: The objective of the study was to further characterize the vascular and ureteral anatomy relative to the midsacral promontory, a landmark often used during sacrocolpopexy, and suggest strategies to avoid complications. STUDY DESIGN: Distances between the right ureter, aortic bifurcation, and iliac vessels to the midsacral promontory were examined in 25 unembalmed female cadavers and 100 computed tomography (CT) studies. Data were analyzed using Pearson χ(2), unpaired Student t test, and analysis of covariance. RESULTS: The average distance between the midsacral promontory and right ureter was 2.7 cm (range, 1.6-3.8 cm) in cadavers and 2.9 cm (range, 1.7-5.0 cm) on CT (P = .209). The closest cephalad vessel to the promontory was the left common iliac vein, the average distance being 2.7 cm (range, 0.95-4.75 cm) in cadavers and 3.0 cm (range, 1.0-6.1 cm) on CT (P = .289). The closest vessel to the right of the promontory was the internal iliac artery, with the average distance of 2.5 cm (range, 1.4-3.9 cm) in cadavers and 2.2 cm (range, 1.2-3.9 cm) on CT (P = .015). The average distance from the promontory to the aortic bifurcation was 5.3 cm (range, 2.8-9.7 cm) in cadavers and 6.6 cm (range, 3.1-10.1 cm) on CT (P < .001). The average distance from the aortic bifurcation to the inferior margin of the left common iliac vein was 2.3 cm (range, 1.2-3.9 cm) in cadavers and 3.5 cm (range, 1.7-5.6 cm) on CT (P < .001). CONCLUSION: The right ureter, right common iliac artery, and left common iliac vein are found within 3 cm from the midsacral promontory. A thorough understanding of the extensive variability in vascular and ureteral anatomy relative to the midsacral promontory should help avoid serious intraoperative complications during sacrocolpopexy.

MR imaging quantitative analysis of fetal Chiari II malformations and associated open neural tube defects: balanced SSFP versus half-Fourier RARE and interobserver reliability.

PURPOSE: To evaluate bSSFP (balanced steady state free precession) and half-Fourier RARE (rapid acceleration with relaxation enhancement) MRI sequences in their ability to demonstrate fetal anatomic landmarks, quantify the degree of cerebellar herniation in Chiari II malformations and level and length of the associated open neural tube defects, as well as evaluate interobserver reliability of these measurements. MATERIALS AND METHODS: Two independent observers retrospectively reviewed MRIs of 37 fetuses with Chiari II malformations and associated open neural tube defects (mean gestational age: 27 weeks 2 days). Comparison of bSSFP and RARE included: (i) Ability to confidently identify anatomic landmarks of the posterior fossa and spine; (ii) Measurements of the foramen magnum, cerebellar tonsillar herniation length, intervertebral disc space level of tonsillar herniation, open neural tube defect length, and disc space start and end level of the open neural tube defect; (iii) Observed conspicuity of anatomic landmarks. RESULTS: There was no significant difference in assessment of cerebellar tonsillar herniation or open neural tube defect level between bSSFP and RARE for either observer. Intervertebral discs were more conspicuous on bSSFP while cerebellar tonsils were more conspicuous on RARE (P < 0.05). Interobserver reliability was strong for both sequences in assessing the foramen magnum (r = 0.95, 0.94), tonsillar herniation length (r = 0.93, 0.95), and open neural tube defect length (r = 0.97, 0.96). CONCLUSION: Despite improved conspicuity of the intervertebral discs with bSSFP and cerebellar tonsils with RARE, there is no significant difference in measurement of hindbrain herniation or open neural tube defect level; interobserver reliability is excellent for both sequences.

Preventing L5-S1 discitis associated with sacrocolpopexy.

OBJECTIVE: To further characterize the anatomy of the fifth lumbar to first sacral (L5-S1) disc space and to provide anatomic landmarks that can be used to predict the locations of the disc, sacral promontory, and surrounding structures during sacrocolpopexy. METHODS: The lumbosacral anatomy was examined in 25 female cadavers and 100 computed tomography (CT) studies. Measurements were obtained using the midpoint of the sacral promontory as a reference. Data were analyzed using Pearson χ, unpaired Student's t test, and analysis of covariance. RESULTS: The average height of the L5-S1 disc was 1.8±0.3 cm (range 1.3-2.8 cm) in cadavers and 1.4±0.4 cm (0.3-2.3) on CT (P<.001). The average angle of descent between the anterior surfaces of L5 and S1 was 60.5±9 degrees (39.5-80.5 degrees) in cadavers and 65.3±8 degrees (42.6-88.6 degrees) on CT (P=.016). The average shortest distance between the S1 foramina was 3.4±0.4 cm in cadavers and 3.0±0.4 cm on CT (P<.001). The average height of the first sacral vertebra (S1) was 3.0±0.2 cm in cadavers and 3.0±0.3 on CT (P=.269). CONCLUSION: In the supine position, the most prominent structure in the presacral space is the L5-S1 disc, which extends approximately 1.5 cm cephalad to the "true" sacral promontory. During sacrocolpopexy, awareness of a 60-degree average drop between the anterior surfaces of L5 and S1 vertebra should assist with intraoperative localization of the sacral promontory and avoidance of the L5-S1 disc. The first sacral nerve can be expected approximately 3 cm from the upper surface of the sacrum and 1.5 cm from the midline. LEVEL OF EVIDENCE: II.