Faculty Bibliography

Purpose: To demonstrate that sonographic morphologic properties of the supraspinatus tendon correlate with mechanical properties, as assessed quantitatively by shear-wave ultrasound elastography.
Material(s) and Method(s): This retrospective study included 36 patients who underwent sonographic evaluation of one or both shoulders on one or multiple dates from June 2013 through October 2014. A shoulder was excluded if the supraspinatus tendon contained calcifications or had undergone surgical repair for a tear. Each sonographic evaluation of each shoulder was regarded as a separate data point, totaling 76 sonographic evaluations of 36 patients. For each sonographic evaluation, the morphologic appearance of the proximal and distal supraspinatus tendon was graded (1 = normal or mild tendinosis without a tear, 2 = moderate or severe tendinosis without a tear, 3 = partial tear, 4 = full-thickness tear) by consensus of 2 musculoskeletal radiologists. In addition, for each sonographic evaluation, sample volumes were randomly placed within the proximal and distal supraspinatus tendon, viewed in the longitudinal dimension, to obtain shear-wave ultrasound elastography measurements. Finally, for 68 of the sonographic evaluations, on the same image used for sample volumes of the supraspinatus tendon, sample volumes were randomly placed within the deltoid muscle to obtain shear-wave ultrasound elastography measurements. Spearman rank correlations assessed the association between tendonmorphology grade and elastographymeasurements. Mann-Whitney tests compared elastography measurements between scans grouped by symptomatology or morphology grade. Bootstrap re-sampling procedures accounted for lack of statistical independence among scans of the same patient.
Result(s): Of the 36 patients, there were 21 males and 15 females (mean age 46, range 23-74). Of the 76 sonographic evaluations, there were 38 males and 38 females (mean age 44, range 23-74), 36 right and 40 left shoulders, and 21 symptomatic and 55 asymptomatic shoulders. The tendon morphology grade and elastography measurements were correlated in both the proximal (p < 0.001) and distal (p = 0.002) supraspinatus tendon. Comparing between grade 1 and grade >= 2 morphology, the elastography measurements differed significantly in both the proximal (p = 0.001) and distal (p = 0.012) supraspinatus tendon. Comparing between grade <= 2 and grade > 2 morphology, the elastography measurements also differed significantly in both the proximal (p = 0.002) and distal (p = 0.004) supraspinatus tendon. Interestingly, deltoid muscle elastography measurements also were associated with the morphology grade of the proximal (p = 0.004) and distal (p = 0.007) supraspinatus tendon; this measurement also differed significantly between asymptomatic and symptomatic scans (p = 0.001).
Conclusion(s): The sonographic morphologic properties of the supraspinatus tendon correlate with mechanical properties, as assessed by shear-wave ultrasound elastography. These findings indicate that shear-wave ultrasound elastography - a non-invasive, relatively inexpensive, and simple examination - can provide an objective measurement of tendon elasticity. Correlation of deltoid muscle elasticity with supraspinatus tendon morphology and symptomatology may be related to the two muscles being a force couple. Further research is needed to assess whether tendon elastography measurements correlate with the MRI morphologic appearance of the tendon and with intraoperative evaluation of tendon quality

Purpose: To see if failure of arthroscopic shoulder stabilization can be predicted by the evaluation of bipolar bone loss on MRI Methods: A retrospective review of 39 consecutive patients (40 shoulders) who underwent arthroscopic capsulolabral repair for recurrent, traumatic, anterior shoulder instability was performed. There were a total of 40 MRIs from 39 patients (31males, 8 females, mean age 31.7 yrs.). Mean follow-up was 19 months. Pre-operative plain radiographs, MRI scans, operative reports, arthroscopic photos, and post-operative records were reviewed for each patient. Surgical failure was defined as recurrent shoulder dislocation and/or persistent apprehension during normal range of motion. Each preoperative MRI scan was evaluated for bipolar bone loss by one musculoskeletal radiologist using the on-track/off-track (OOT) method in which the glenoid track (GT) and Hill-Sachs interval (HSI) aremeasured. According to this technique, the GT is calculated as 0.83D-d in which "D" represents the diameter of the intact glenoid and "d" corresponds to the amount of glenoid bone loss. The HSI represents the width of the Hill-Sachs lesion plus the width of the intact bone bridge between the rotator cuff attachment and the lateral aspect of the Hill-Sachs lesion. All measurements were in millimeters. Lesions were considered "off-track" if the HSI exceeded the GT and "on-track" if the HSI was less than the GT. These findings were then compared to the corresponding post-operative outcomes. Statistical analysis was carried out using the Fisher exact test.
Result(s): Of the 40 shoulders evaluated, 6 were considered surgical failures (3 with recurrent dislocation and 3 with persistent apprehension). The OOT method correctly predicted 1 of these failures and falsely predicted 6 failures in shoulders that were clinically stable. There was no significant difference when comparing stable to unstable shoulders with regards to age, size of GTand HSI. Overall, the OOT method sensitivity was 16.7% (1/6), specificity 82.4% (28/34), positive predictive value 14.3% (1/7), negative predictive value 84.9% (28/33) and overall accuracy 72.5% (29/40).
Conclusion(s): MRI evaluation of bipolar (humeral and glenoid) bone loss using the on-track/off-track method is a moderately accurate and specific, but insensitive technique to predict surgical failure after arthroscopic capsulolabral repair for shoulder instability

Purpose: To see if 3D imaging could improve our understanding of rotator cuff tendon tear shapes on MRI.
Method(s): We performed a retrospective review of 1.5T/3T MR examinations, conducted over an 18-month period, of patients with arthroscopically proven full- thickness rotator cuff tears. Two orthopaedic surgeons reviewed the operative reports/arthroscopic photos for each patient, and characterized, in consensus, the shape of the tear based on a comparison of the tear's width (size) and length (retraction), and involvement of the rotator interval without measurements into the following categories: crescent, longitudinal, U or L-shaped longitudinal, and massive- type. Two musculoskeletal radiologists reviewed the pre-operative MR examination for each patient independently/blind to the arthroscopic findings. Initially, the readers characterized the shape of the tendon tears by reviewing the standard 2DMR sequences and using the same criteria as the surgeons used during their review of the scope images. Next, the readers measured and documented the width and length of each tendon tear using the 2D images. The shape of the tear was then classified based on a previously published MR-based system as either crescent, longitudinal, U or L-shaped, or massive. Four weeks after the initial imaging evaluation, 3DMR reconstructions of each tear were reviewed and the shape documented by each radiologist independently/blind to the arthroscopic results using the same system used by our orthopaedic colleagues. These results were then compared to the 2D imaging evaluations and arthroscopic findings. Statistical analysis included 95% confidence intervals, McNemar test, and intra-class correlation coefficients.
Result(s): A total of 34 patients were included in the study; 21 had crescent shaped tears and 13 had longitudinal tears during arthroscopy. Of the 13 longitudinal tears, 8 were subtyped as U-shaped, while 5 were described as L-shaped. 6 of the 13 longitudinal tears were additionally classified as massive-type. There was no significant difference when comparing the accuracy of the tear shape characterizations made on 2DMR imaging without measurements (pre) and with measurements (post). The accuracy for differentiating between crescent shaped, longitudinal, and massive tears was the same for reader 1, 70.6% (24/34; p=1) and more accurate using the post 2D data for reader 2 (67.6%(post) vs. 61.8%(pre), p=0.5). The accuracy for tear shape characterization between crescent and longitudinal using the 3D reconstructions for reader #1 was 97.1%(33/34) and 88.2% (30/34) for reader #2. When this characterization included subclassifying the longitudinal tears into U or-L shaped, the accuracy for reader #1 was 97.1% and 82.4% for reader #2. When further characterizing the longitudinal tears as massive or not, both readers had an accuracy of 76.9% (10/13). The overall accuracy of the 3D reconstructions was 82.4% (56/68), significantly different (p=0.021) from the post 2D accuracy (64.7%) and pre 2D accuracy (60.3%, p=0.001). The intraclass correlation coefficient for the 2D measurements of width and length were 0.81, moderate agreement, for width and 0.95, strong agreement, for length.
Conclusion(s): Our study has demonstrated that 3DMR reconstructions of the rotator cuff improve the accuracy of characterizing rotator cuff tear shapes compared to the current 2DMR imaging based techniques

Background: A combined PET/MR scanner with simultaneous acquisition allows direct correlations of PET data with MR-detected parameters on the same subject at the same time. This multi-modal analysis will facilitate the identification of an optimal biomarker. Here we report our study to compare dynamic SUV and cortical thickness between controls (HC) and epilepsy patients (Ep) using simultaneous PET/MR. Methods: Subjects (11 HC and 27 Ep) were imaged on a combined PET/MR scanner (Biograph muMR, Siemens). After FDG injection, dynamic PET scans and simultaneous MR imaging (including T1, T2 and other sequences) were acquired for ~90 minutes. Dixon sequence was acquired for attenuation correction. PET data were reconstructed using the e7tools provided by Siemens. Images were processed using Freesurfer, a fully automated image analysis tool. Over 100 masks (ROIs), including left and right, for cortical and subcortical regions were generated. Statistical analyses on mean SUV for entire study (SUVmean-all), meanSUV derived from the last three frames (SUVmean-late), and mean cortical thickness were compared between groups. Results: Based on Mann-Whitney U tests, SUVmean-late values showed significant differences between groups for most ROIs, while no difference was seen with SUVmean-all. Temporal-Mid-tempocci consistently showed significant difference when normalized SUV values were compared (p <0.01, by individual subject's mean cortical, white matter or global brain). Significant cortical thinning (Epi vs. HC) was detected bilaterally (left, right) within localized regions, such as precentral (p=0.017, 0.012) and superiorfrontal (p=0.016, 0.001). Binary logistic regression indicated that both SUVmean-late and cortical thickness were independent predictors for epilepsy. Conclusions: Our results suggest that simultaneous PET/ MR imaging provides a useful imaging tool to identify regional abnormality, and that SUVmean-late and cortical thickness are independent biomarkers for epilepsy

BACKGROUND: Glucocorticoid-induced osteoporosis (GIO) is the most common secondary form of osteoporosis, and glucocorticoid users are at increased risk for fracture compared with nonusers. There is no established relationship between bone mineral density (BMD) and fracture risk in GIO. We used 3 Tesla (T) MRI to investigate how proximal femur microarchitecture is altered in subjects with GIO. METHODS: This study had institutional review board approval. We recruited 6 subjects with long-term (> 1 year) glucocorticoid use (median age = 52.5 (39.2-58.7) years) and 6 controls (median age = 65.5 [62-75.5] years). For the nondominant hip, all subjects underwent dual-energy x-ray absorptiometry (DXA) to assess BMD and 3T magnetic resonance imaging (MRI, 3D FLASH) to assess metrics of bone microarchitecture and strength. RESULTS: Compared with controls, glucocorticoid users demonstrated lower femoral neck trabecular number (-50.3%, 1.12 [0.84-1.54] mm(-1) versus 2.27 [1.88-2.73] mm(-1) , P = 0.02), plate-to-rod ratio (-20.1%, 1.48 [1.39-1.71] versus 1.86 [1.76-2.20], P = 0.03), and elastic modulus (-64.8% to -74.8%, 1.54 [1.22-3.19] GPa to 2.31 [1.87-4.44] GPa versus 6.15 [5.00-7.09] GPa to 6.59 [5.58-7.31] GPa, P < 0.05), and higher femoral neck trabecular separation (+192%, 0.705 [0.462-1.00] mm versus 0.241 [0.194-0.327] mm, P = 0.02). There were no differences in femoral neck trabecular thickness (-2.7%, 0.193 [0.184-0.217] mm versus 0.199 [0.179-0.210] mm, P = 0.94) or femoral neck BMD T-scores (+20.7%, -2.1 [-2.8 to -1.4] versus -2.6 [-3.3 to -2.5], P = 0.24) between groups. CONCLUSION: The 3T MRI can potentially detect detrimental changes in proximal femur microarchitecture and strength in long-term glucocorticoid users. J. MAGN. RESON. IMAGING 2015;42:1489-1496.

BACKGROUND AND PURPOSE: The pituitary gland is located outside of the blood-brain barrier. Dynamic T1 weighted contrast enhanced sequence is considered to be the gold standard to evaluate this region. However, it does not allow assessment of intrinsic permeability properties of the gland. Our aim was to demonstrate the utility of radial volumetric interpolated brain examination with the golden-angle radial sparse parallel technique to evaluate permeability characteristics of the individual components (anterior and posterior gland and the median eminence) of the pituitary gland and areas of differential enhancement and to optimize the study acquisition time. MATERIALS AND METHODS: A retrospective study was performed in 52 patients (group 1, 25 patients with normal pituitary glands; and group 2, 27 patients with a known diagnosis of microadenoma). Radial volumetric interpolated brain examination sequences with golden-angle radial sparse parallel technique were evaluated with an ROI-based method to obtain signal-time curves and permeability measures of individual normal structures within the pituitary gland and areas of differential enhancement. Statistical analyses were performed to assess differences in the permeability parameters of these individual regions and optimize the study acquisition time. RESULTS: Signal-time curves from the posterior pituitary gland and median eminence demonstrated a faster wash-in and time of maximum enhancement with a lower peak of enhancement compared with the anterior pituitary gland (P < .005). Time-optimization analysis demonstrated that 120 seconds is ideal for dynamic pituitary gland evaluation. In the absence of a clinical history, differences in the signal-time curves allow easy distinction between a simple cyst and a microadenoma. CONCLUSIONS: This retrospective study confirms the ability of the golden-angle radial sparse parallel technique to evaluate the permeability characteristics of the pituitary gland and establishes 120 seconds as the ideal acquisition time for dynamic pituitary gland imaging.

OBJECTIVE: Sequential computed tomography (CT) technique remains the most common protocol for CT evaluation of the head despite nearly universal adoption of continuous technique for all other body parts. This may be attributable to the belief by radiologists that this technique is superior to helical scanning uniquely for this indication. This study attempts to clarify the issue. METHODS: A phantom evaluation and a prospective randomized clinical image quality trial were performed comparing sequential and helical technique using the most current generation 128-row detector CT scanner. RESULTS: Phantom evaluation demonstrated equivalence between the 2 techniques for low-contrast resolution and line pair spatial discrimination. Continuous scanning provided the highest contrast-to-noise ratio. There was no significant difference between the 2 techniques regarding image quality except for cortical visualization at the cerebral hemispheres, which was subtly but significantly superior for sequential technique. CONCLUSIONS: Head CT image quality for sequential and continuous techniques are virtually equivalent.

OBJECTIVE: To measure background parenchymal enhancement (BPE) and compare with other contrast enhancement values and diffusion-weighted MRI parameters in healthy and cancerous breast tissue at the clinical level. MATERIALS AND METHODS: This HIPAA-compliant, IRB approved retrospective study enrolled 77 patients (38 patients with breast cancer - mean age 51.8+/-10.0 years; 39 high-risk patients for screening evaluation - mean age 46.3+/-11.7 years), who underwent contrast-enhanced 3T breast MRI. Contrast enhanced MRI and diffusion-weighted imaging were performed to quantify BPE, lesion contrast enhancement, and apparent diffusion coefficient (ADC) metrics in fibroglandular tissue (FGT) and lesions. RESULTS: BPE did not correlate with ADC values. Mean BPE for the lesion-bearing patients was higher (43.9%) compared to that of the high-risk screening patients (28.3%, p=0.004). Significant correlation (r=0.37, p<0.05) was found between BPE and lesion contrast enhancement. CONCLUSION: No significant association was observed between parenchymal or lesion enhancement with conventional apparent diffusion metrics, suggesting that proliferative processes are not co-regulated in cancerous and parenchymal tissue.