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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.

Purpose The purpose of this work was to develop and evaluate a system consisting of an insertable gradient, RF coils, and animal positioning hardware to enable imaging of the internal structure of the cochlea and other inner ear structures of a guinea pig model at 3T. Methods Transmit and receive RF coils, and an animal positioning system, were developed and integrated with an insertable gradient and animal monitoring system for improved guinea pig cochlea imaging when compared to a standard clinical 3T MRI system. A resolution phantom with 120 μm line separations was used to assess the contrast improvements with the insertable gradient. A homogeneous phantom was used to assess the SNR and homogeneity of the RF coils. FLASH imaging was used to observe the temporal passage of gadolinium contrast through the guinea pig cochlea. Results The insertable gradient enabled increased resolution imaging with nearly twice the contrast-to-noise ratio. The small animal array had better SNR for imaging the guinea pig cochlea (about 14 mm deep) than the commercial Siemens wrist coil (2.2×) and the small birdcage coil (1.6×). The positioning device kept the animal secure and stationary. Injected gadolinium contrast allowed visualization of the internal cochlear structures with FLASH image acquisition, which achieved 100 μm isotropic resolution images in 33 min. Conclusion The specialized RF coils and animal holding equipment designed to operate within the composite gradient enabled higher resolution images than could be obtained from the available RF coils operating in the conventional gradients on the clinical MRI system. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 44B: 89–101, 2015

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. J. Magn. Reson. Imaging 2013;38:786–793. © 2013 Wiley Periodicals, Inc.

BACKGROUND AND PURPOSE: While enhanced T1WI is considered the “gold standard” for detection of internal auditory canal pathology, unenhanced fluid-sensitive sequences have shown high sensitivity for lesion identification. Our purpose was to evaluate the diagnostic accuracy of an unenhanced MR imaging protocol using axial CISS and coronal T2WI for detection of small (10 mm or less) internal auditory canal lesions. MATERIALS AND METHODS: Twenty-three patients with small internal auditory canal lesions and 13 patients without lesions who had undergone MR imaging using the screening protocol and confirmatory gadolinium-enhanced thin section T1WI were identified. Two blinded neuroradiologists retrospectively evaluated all examinations using 1) only axial CISS, 2) only coronal T2WI, and 3) axial and coronal sequences together. Accuracy, specificity, sensitivity, and interobserver agreement were assessed. RESULTS: Median maximum lesion dimension was 4 mm (range, 2–10 mm). Accuracy, specificity, and sensitivity for axial CISS alone were 0.94, 0.96, and 0.91 for observer 1 and 0.94, 0.92, and 1.00 for observer 2. The data for the coronal T2WI sequence only were 0.94, 0.96, and 0.91 for observer 1, and 0.99, 1.00, and 0.96 for observer 2. Using axial and coronal sequences, the data were 0.97, 0.96, and 1.00 for observer 1, and 0.99, 0.98, and 1.00 for observer 2. κ coefficients were 0.84 for the axial sequence only, 0.90 for coronal only, and 0.91 for axial and coronal both. CONCLUSIONS: Screening noncontrast MR imaging using a combination of axial CISS and coronal T2WI sequences can detect small internal auditory canal lesions with 100% sensitivity and excellent interobserver agreement.

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.

BACKGROUND AND PURPOSE: The craniopharyngeal canal is a rare, well-corticated defect through the midline of the sphenoid bone from the sellar floor to the anterosuperior nasopharyngeal roof. We reviewed a series of craniopharyngeal canals to determine a system of classification that might better our understanding of this entity, highlight the range of associated pathologic conditions, and optimize patient treatment. MATERIALS AND METHODS: Available MR imaging, CT, and clinical data (from 1989–2013) of 29 patients (10 female, 15 male, 4 unknown; median age, 4 years; age range, 1 day–65 years) with craniopharyngeal canals were retrospectively examined. Qualitative assessment included orthotopic or ectopic adenohypophysis and the presence of a tumor and/or cephalocele. The midpoint anteroposterior diameter was measured. Clinical and imaging data were evaluated for pituitary dysfunction and accompanying anomalies. RESULTS: Craniopharyngeal canals were qualitatively separated into 3 types: incidental canals (type 1); canals with ectopic adenohypophysis (type 2); and canals containing cephaloceles (type 3A), tumors (type 3B), or both (type 3C), including pituitary adenoma, craniopharyngioma, dermoid, teratoma, and glioma. Quantitative evaluation showed a significant difference (P < .0001) in the anteroposterior diameters of type 1 canals (median, 0.8; range, 0.7–1.1 mm), type 2 canals (median, 3.9, range, 3.5–4.4 mm), and type 3 canals (median, 9.0; range, 5.9–31.0 mm) imparting small, medium, and large descriptors. Canals with cephaloceles all contained an ectopic adenohypophysis. The craniopharyngeal canals were associated with pituitary dysfunction (6/29) and congenital anomalies (8/29). CONCLUSIONS: Accurate diagnosis and classification of craniopharyngeal canals are valuable to characterize lesions requiring surgery, identify patients with potential pituitary dysfunction, and avoid iatrogenic hypopituitarism or CSF leak during surgical resection of nasopharyngeal masses.

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.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.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).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.II.

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.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.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).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.

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.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.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 (P0.05). 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).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.