The purpose of this study was to identify the trends and demographics of patients undergoing arthroscopic anterior cruciate ligament (ACL) reconstruction in the United States. Patients who underwent arthroscopic ACL reconstruction between 2004 and 2009 were identified by searching Current Procedural Terminology codes in the PearlDiver Patient Record Database (PearlDiver Technologies, Fort Wayne, IN). The year of procedure, age, gender, and region of the United States were recorded for each patient. Associated meniscal procedures and the absence or presence of a femoral nerve block were also recorded. The incidence of ACL reconstruction significantly increased over the study period, from 40.9 cases per 10,000 patients in 2004 to 47.8 in 2009 (p < 0.001). Of these cases, 92.8% were associated with either meniscectomy or meniscal repair. ACL reconstruction was performed most commonly in patients aged 10 to 29 years (p < 0.001). A significant male predominance was observed with an incidence ratio of male-to-female of 2.03 (p < 0.001). The frequency of females undergoing ACL reconstruction as a proportion of the total number of annual cases increased from 2,295 in 2004 to 3,476 in 2009 (p = 0.0031). A significant increase in the annual proportion of ACL reconstruction performed under femoral nerve block was also observed, from 2.0% in 2004 to 8.3% in 2009 (p < 0.001). The greatest incidence of ACL reconstruction occurred in the Western region of the United States. An increase in the rate of arthroscopic ACL reconstruction was observed between 2004 and 2009 and 92.8% of the ACL reconstructions were associated with a meniscal procedure. The majority of cases were performed in patients aged 10 to 29 years, with a male predominance. Increases were observed in the number of female cases and proportion performed under a femoral nerve block. The Western region of the United States was found to have a higher incidence of ACL reconstruction.

Background: Signal contamination from long T2 water is a major challenge in direct imaging of myelin with MRI. Nulling of the unwanted long T2 signals can be achieved with an inversion recovery (IR) preparation pulse to null long T2 white matter within the brain. The remaining ultrashort T2 signal from myelin can be detected with an ultrashort echo time (UTE) sequence.Purpose: To develop patient-specific whole-brain myelin imaging with a three-dimensional double-echo sliding inversion recovery (DESIRE) UTE sequence. Materials and Methods:The DESIRE UTE sequence generates a series of IR images with different inversion times during a single scan. The optimal inversion time for nulling long T2 signal is determined by finding minimal signal on the second echo. Myelin images are generated by subtracting the second echo image from the first UTE image. To validate this method, a prospective study was performed in phantoms, cadaveric brain specimens, healthy volunteers, and patients with multiple sclerosis (MS). A total of 20 healthy volunteers (mean age, 40 years 6 13 [standard deviation], 10 women) and 20 patients with MS (mean age, 58 years 6 8; 15 women) who underwent MRI between November 2017 and February 2019 were prospectively included. Analysis of variance was performed to evaluate the signal difference between MS lesions and normal-appearing white matter in patients with MS.Results: High signal intensity and corresponding T2* and T1 of the extracted myelin vesicles provided evidence for direct imaging of ultrashort-T2 myelin protons using the UTE sequence. Gadobenate dimeglumine phantoms with a wide range of T1 values were selectively suppressed with DESIRE UTE. In the ex vivo brain study of MS lesions, signal loss was observed in MS lesions and was conformed with histologic analysis. In the human study, there was a significant reduction in normalized signal intensity in MS lesions compared with that in normal-appearing white matter (0.19 6 0.10 vs 0.76 6 0.11, respectively; P , .001). Conclusion:The double-echo sliding inversion recovery ultrashort echo time sequence can generate whole-brain myelin images specifically with a clinical 3-T scanner.

Background: Rotator cuff tendons (RCTs) are challenging to image due to the "magic angle effect" and their short T 2 . Purpose: To assess the degree of magic angle sensitivity of human RCTs and to utilize a 3D ultrashort echo time Cones sequence with magnetization transfer preparation (UTE-Cones-MT) and two-pool quantitative MT modeling with histological correlation. We hypothesized that MT parameters would be less sensitive to the magic angle compared with conventional T 2 measurements. Study Type: Prospective imaging pathologic correlation. Specimen: Twenty cadaveric rotator cuff tendons were imaged at five sample orientations ranging from 0-908 relative to the B 0 field. Field Strength/Sequence: 3T/3D UTE-Cones-MT and Carr-Purcell-Meiboom-Gill (CPMG). Assessment: Two-pool quantitative MT modeling parameters and T 2 values were calculated in regions of interest drawn by a medical physicist. Histopathological analysis was performed and mild and severe tendinopathy groups were assigned by a histopathologist and histotechnician. Statistical Tests: Coefficients of variations (CVs) were calculated for measures between the different orientations and group means were compared for each measure. Results: CVs of T 2 and macromolecular fractions between orientations were 26.14 6 16.82% and 6.18 6 2.77% (mean 6 SD), respectively. T 2 measurements at 08, 278, 708, and 908 showed significant differences between the two histological groups (P 5 0.004, 0.008, 0.003, and 0.015, respectively), but not at 558 (P 5 0.611). Mean T 2 value ranges between orientations for the mild and severe tendinopathy groups were 15.27-30.32 msec and 20.81-35.85 msec, respectively, showing overlap despite statistically significant differences (P 5 0.003). Macromolecular fractions at all angles showed significant differences between the two groups (P < 0.0001). Mean fraction ranges between orientations for the mild and severe tendinopathy groups were 14.32-17.17% and 10.00-13.75% respectively (P < 0.0001) with no overlap. Data Conclusion: Compared with T 2 , macromolecular fraction obtained with the 3D UTE-Cones-MT technique is resistant to the magic angle effect and is more sensitive to RCT degeneration. Level of Evidence: 1 Technical Efficacy: Stage 2