Comparison of standard hip MR arthrographic imaging planes and sequences for detection of arthroscopically proven labral tear.

OBJECTIVE: The purpose of this study was to compare multiple imaging planes and two pulse sequences for detection of arthroscopically proven labral tears. MATERIALS AND METHODS: From March 2004 through June 2007, acetabular labral tear was diagnosed at hip arthroscopy of 189 patients. Preoperative MR arthrography of the affected hip was performed on 144 patients at our institution. These MR arthrograms were retrospectively reviewed by a musculoskeletal fellow and two musculoskeletal radiologists. The sequences used were coronal T1-weighted with fat saturation, coronal T2-weighted with fat saturation, sagittal T1-weighted with fat saturation, axial oblique T1-weighted with fat saturation, sagittal oblique T1-weighted with fat saturation, and axial T1-weighted. Using consensus, the reviewers evaluated images obtained with each sequence for the presence of a tear, number of slices on which a tear was seen, and the signal intensity of the tear. RESULTS: Among the 144 tears, 97.2% were identified as definitely present on images obtained with at least one of the sequences. The axial oblique sequence had the highest individual detection rate (85.0%). The detection rates for the sagittal T1-weighted (74.6%), coronal T1-weighted (67.4%), and coronal T2-weighted (63.6%) sequences were intermediate. Detection rates with the axial T1-weighted (29.9%) and sagittal oblique (18.2%) sequences were low. With the combination of three sequences (coronal T2-weighted with fat saturation, axial oblique T1-weighted with fat saturation, and sagittal T1-weighted with fat saturation), 95.8% of the 144 tears were identified as definitely present. Twenty-eight percent of tears had a signal intensity less than that of gadolinium or fluid. CONCLUSION: Imaging in the axial oblique plane has the highest rate of detection of acetabular labral tears. More than 95% of tears were identified with the use of three imaging planes. Signal intensity within a tear does not have to be equal to that of gadolinium or fluid to confirm the diagnosis of labral tear.

Anatomic development of the oral and pharyngeal portions of the vocal tract: an imaging study.

The growth of the vocal tract (VT) is known to be non-uniform insofar as there are regional differences in anatomic maturation. This study presents quantitative anatomic data on the growth of the oral and pharyngeal portions of the VT from 605 imaging studies for individuals between birth and 19 years. The oral (horizontal) portion of the VT was segmented into lip-thickness, anterior-cavity-length, oropharyngeal-width, and VT-oral, and the pharyngeal (vertical) portion of the VT into posterior-cavity-length, and nasopharyngeal-length. The data were analyzed to determine growth trend, growth rate, and growth type (neural or somatic). Findings indicate differences in the growth trend of segments/variables analyzed, with significant sex differences for all variables except anterior-cavity-length. While the growth trend of some variables displays prepubertal sex differences at specific age ranges, the importance of such localized differences appears to be masked by overall growth rate differences between males and females. Finally, assessment of growth curve type indicates that most VT structures follow a combined/hybrid (somatic and neural) growth curve with structures in the vertical plane having a predominantly somatic growth pattern. These data on the non-uniform growth of the vocal tract reveal anatomic differences that contribute to documented acoustic differences in prepubertal speech production.

Estimating head circumference from pediatric imaging studies an improved method.

RATIONALE AND OBJECTIVES: Head circumference (HC) is an important developmental measure used both clinically and in research. This paper advances a method to estimate HC from imaging studies when a direct HC-tape measurement cannot be secured. Unlike former approaches, the model takes into account the fact that growth is nonlinear, and that HC growth rates are sexually dimorphic. MATERIALS AND METHODS: A model was first established based on published data to represent the normative HC growth curves for males and females. Then, using magnetic resonance (MR) studies of 90 subjects (birth to 18 years), a linear method to estimate HC was adapted to take into account the nonlinear and sex-specific HC normative growth curves. The accuracy of this model was tested prospectively by comparing the estimated HC with HC measurements from twelve computed tomography (CT) studies using the perimeter tracing of oblique slices that correspond to the plane at which a clinical HC-tape measurement is secured. RESULTS: Prospective comparison of estimated HC to HC tracings using a paired t-test validates that the model provides an accurate estimation of the measured HC (t=-.845, p=0.416 overall; t=.54, p=.615 for females and t=-2.34, p=.066 for males). DISCUSSION: HC can be calculated indirectly from imaging studies. The model is highly predictive of HC-tape measurements and provides the physician or scientist with a very reliable method to secure HC when it is not feasible to secure the HC-tape measurement.

Sublabral foramen and buford complex: inferior extent of the unattached or absent labrum in 50 patients.

PURPOSE: To determine the inferiormost extent of the anterosuperior labral variants on conventional transverse MR images. MATERIALS AND METHODS: We reviewed transverse MR images in 50 consecutive patients with a sublabral foramen or Buford complex at arthroscopy. Images were randomly mixed with those of 58 patients with either a normal labrum (n = 20) or an anterior labral tear (n = 38) at arthroscopy. MR imaging was fat suppressed fast spin echo intermediate or T2 weighted (repetition time msec/effective echo time msec, 1,800-3,000/30-102). Two radiologists evaluated by means of consensus the anterior labrum while blinded to patient history and arthroscopic results. Transverse images obtained through the glenoid fossa were totalled to determine the midpoint. Sensitivity, specificity, and accuracy of MR for depicting a sublabral foramen or Buford complex were calculated along with 95% CIs, by using surgical findings as the reference standard. RESULTS: The sensitivity of MR for diagnosing a sublabral foramen or Buford complex was 0.94 (47 of 50 patients, 95% CI: 0.87, 1.00), specificity was 0.80 (16 of 20 patients, 95% CI: 0.62, 0.97), and accuracy was 0.90 (63 of 70 patients, 95% CI: 0.82, 0.97). The anterior labrum was abnormal on the first transverse section inferior to the midpoint in nine (18%) patients. The labrum was also abnormal on the second section below the midpoint in three (6%) patients. Because of the anterior tilt of the scapula, the midpoint was near the anterior glenoid notch at about the position between 2- and 3-o'clock. CONCLUSION: The labrum may be unattached or absent on the first two transverse images obtained below the midpoint.