Erika J. Ulbrich

Age- and Level-Dependence of Fatty Infiltration in Lumbar Paravertebral Muscles of Healthy Volunteers.

BACKGROUND AND PURPOSE: Normative age-related decline in paravertebral muscle quality is important for reference to disease and risk identification in patients. We aimed to establish age- and vertebral level–dependence of paravertebral (multifidus and erector spinae) muscle volume and fat content in healthy adult volunteers. MATERIALS AND METHODS: In this prospective study multifidus and erector spinae fat signal fraction and volume at lumbar levels L1–L5 were measured in 80 healthy volunteers (10 women and men per decade, 20–62 years of age) by 2-point Dixon 3T MR imaging. ANOVA with post hoc Bonferroni correction compared fat signal fraction and volume among subgroups. Pearson and Spearman analysis were used for correlations (P < .05). RESULTS: Fat signal fraction was higher in women (17.8% ± 10.7%) than men (14.7% ± 7.8%; P < .001) and increased with age. Multifidus and erector spinae volume was lower in women (565.4 ± 83.8 cm3) than in men (811.6 ± 98.9 cm3; P < .001) and was age-independent. No differences in fat signal fraction were shown between the right and left paravertebral muscles or among the L1, L2, and L3 lumbar levels. The fat signal fraction was highest at L5 (women, 31.9% ± 9.3%; men, 25.7% ± 8.0%; P < .001). The fat signal fraction at L4 correlated best with total lumbar fat signal fraction (women, r = 0.95; men, r = 0.92, P < .001). Total fat signal fraction was higher in the multifidus compared with erector spinae muscles at L1–L4 for both sexes (P < .001). CONCLUSIONS: Lumbar paravertebral muscle fat content increases with aging, independent of volume, in healthy volunteers 20–62 years of age. Women, low lumbar levels, and the multifidus muscle are most affected. Further study examining younger and older subjects and the functional impact of fatty infiltrated paravertebral muscles are warranted.

Systematic analysis of the intravoxel incoherent motion threshold separating perfusion and diffusion effects: Proposal of a standardized algorithm.

To systematically evaluate the dependence of intravoxel‐incoherent‐motion (IVIM) parameters on the b‐value threshold separating the perfusion and diffusion compartment, and to implement and test an algorithm for the standardized computation of this threshold.

Are There Cervical Spine Findings at MR Imaging That Are Specific to Acute Symptomatic Whiplash Injury? A Prospective Controlled Study with Four Experienced Blinded Readers

PURPOSE To compare the magnetic resonance (MR) imaging findings in patients with acute whiplash injury with those in matched control subjects. MATERIALS AND METHODS In a prospective multicenter controlled study, from 2005 to 2008, 100 consecutive patients underwent 1.5-T MR imaging examinations of the cervical spine within 48 hours after a motor vehicle accident. Findings in these patients were compared in a blinded fashion with those in 100 age- and sex-matched healthy control subjects. Four blinded independent readers assessed the presence of occult vertebral body and facet fractures, vertebral body and facet contusions, intervertebral disk herniations, ligamentum nuchae strains, ligamentum nuchae tears, muscle strains or tears, and perimuscular fluid. Accuracy (as compared with clinical findings) and interobserver reliability were calculated. RESULTS Accuracy of MR imaging and interreader reliability were generally poor (sensitivity, 0.328; specificity, 0.728; positive and negative likelihood ratios, 1.283 and 1.084, respectively). MR imaging findings significantly associated with whiplash injuries were occult fracture (P<.01), bone marrow contusion of the vertebral body (P=.01), muscle strain (P<.01) or tear (P<.01), and the presence of perimuscular fluid (P<.01). While 10 findings thought to be specific for whiplash trauma were significantly (P<.01) more frequent in patients (507 observations), they were also regularly found in healthy control subjects (237 observations). There were no serious occult injuries that required immediate therapy. CONCLUSION MR imaging at 1.5 T reveals only limited evidence of specific changes to the cervical spine and the surrounding tissues in patients with acute symptomatic whiplash injury compared with healthy control subjects.

STIR sequence with increased receiver bandwidth of the inversion pulse for reduction of metallic artifacts.

OBJECTIVE The purpose of this study was to evaluate a STIR sequence with an optimized inversion pulse that entails use of increased receiver bandwidth for metal artifact reduction. CONCLUSION Image distortion, artifacts, insufficient fat suppression, and detection of relevant findings improved with the STIR optimized inversion pulse, which was associated with significant artifact reduction.

Cervical muscle area measurements in whiplash patients: Acute, 3, and 6 months of follow-up.

To investigate the role of the cervical spine muscles in whiplash injury. We hypothesized that (i) cervical muscle hypotrophy would be evident after a 6‐month follow‐up and, (ii) cervical muscle hypotrophy would correlate with symptom persistence probably related to pain or inactivity.

PROPELLER Technique to Improve Image Quality of MRI of the Shoulder

OBJECTIVE The purpose of this article is to evaluate the use of the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technique for artifact reduction and overall image quality improvement for intermediate-weighted and T2-weighted MRI of the shoulder. SUBJECTS AND METHODS One hundred eleven patients undergoing MR arthrography of the shoulder were included. A coronal oblique intermediate-weighted turbo spin-echo (TSE) sequence with fat suppression and a sagittal oblique T2-weighted TSE sequence with fat suppression were obtained without (standard) and with the PROPELLER technique. Scanning time increased from 3 minutes 17 seconds to 4 minutes 17 seconds (coronal oblique plane) and from 2 minutes 52 seconds to 4 minutes 10 seconds (sagittal oblique) using PROPELLER. Two radiologists graded image artifacts, overall image quality, and delineation of several anatomic structures on a 5-point scale (5, no artifact, optimal diagnostic quality; and 1, severe artifacts, diagnostically not usable). The Wilcoxon signed rank test was used to compare the data of the standard and PROPELLER images. RESULTS Motion artifacts were significantly reduced in PROPELLER images (p < 0.001). Observer 1 rated motion artifacts with diagnostic impairment in one patient on coronal oblique PROPELLER images compared with 33 patients on standard images. Ratings for the sequences with PROPELLER were significantly better for overall image quality (p < 0.001). Observer 1 noted an overall image quality with diagnostic impairment in nine patients on sagittal oblique PROPELLER images compared with 23 patients on standard MRI. CONCLUSION The PROPELLER technique for MRI of the shoulder reduces the number of sequences with diagnostic impairment as a result of motion artifacts and increases image quality compared with standard TSE sequences. PROPELLER sequences increase the acquisition time.

Connectomic and Surface-Based Morphometric Correlates of Acute Mild Traumatic Brain Injury

Reduced integrity of white matter (WM) pathways and subtle anomalies in gray matter (GM) morphology have been hypothesized as mechanisms in mild traumatic brain injury (mTBI). However, findings on structural brain changes in early stages after mTBI are inconsistent and findings related to early symptoms severity are rare. Fifty-one patients were assessed with multimodal neuroimaging and clinical methods exclusively within 7 days following mTBI and compared to 53 controls. Whole-brain connectivity based on diffusion tensor imaging was subjected to network-based statistics, whereas cortical surface area, thickness, and volume based on T1-weighted MRI scans were investigated using surface-based morphometric analysis. Reduced connectivity strength within a subnetwork of 59 edges located predominantly in bilateral frontal lobes was significantly associated with higher levels of self-reported symptoms. In addition, cortical surface area decreases were associated with stronger complaints in five clusters located in bilateral frontal and postcentral cortices, and in the right inferior temporal region. Alterations in WM and GM were localized in similar brain regions and moderately-to-strongly related to each other. Furthermore, the reduction of cortical surface area in the frontal regions was correlated with poorer attentive-executive performance in the mTBI group. Finally, group differences were detected in both the WM and GM, especially when focusing on a subgroup of patients with greater complaints, indicating the importance of classifying mTBI patients according to severity of symptoms. This study provides evidence that mTBI affects not only the integrity of WM networks by means of axonal damage but also the morphology of the cortex during the initial post-injury period. These anomalies might be greater in the acute period than previously believed and the involvement of frontal brain regions was consistently pronounced in both findings. The dysconnected subnetwork suggests that mTBI can be conceptualized as a dysconnection syndrome. It remains unclear whether reduced WM integrity is the trigger for changes in cortical surface area or whether tissue deformations are the direct result of mechanical forces acting on the brain. The findings suggest that rapid identification of high-risk patients with the use of clinical scales should be assessed acutely as part of the mTBI protocol.

Normative MR Cervical Spinal Canal Dimensions

PURPOSE To provide normal values of the cervical spinal canal and spinal cord dimensions in several planes with respect to spinal level, age, sex, and body height. MATERIALS AND METHODS This study was approved by the institutional review board; all individuals provided signed informed consent. In a prospective multicenter study, two blinded raters independently examined cervical spine magnetic resonance (MR) images of 140 healthy volunteers who were white. The midsagittal diameters and areas of spinal canal and spinal cord, respectively, were measured at the midvertebral levels of C1, C3, and C6. A multivariate general linear model described the influence of sex, body height, age, and spinal level on the measured values. RESULTS There were differences for sex, spinal level, interaction between sex and level, and body height, while age had significant yet limited influence. Normative ranges for the sagittal diameters and areas of spinal canal and spinal cord were defined at C1, C3, and C6 levels for men and women. In addition to a calculation of normative ranges for a specific sex, spinal level, age, and body height data, data for three different height subgroups at 45 years of age were extracted. These results show a range of the spinal canal dimensions at C1 (from 10.7 to 19.7 mm), C3 (from 9.4 to 17.2 mm), and C6 (from 9.2 to 16.8 mm) levels. CONCLUSION The dimensions of the cervical spinal canal and cord in healthy individuals are associated with spinal level, sex, age, and height. Online supplemental material is available for this article.

Quantitative and qualitative MR‐imaging assessment of vastus medialis muscle volume loss in asymptomatic patients after anterior cruciate ligament reconstruction

Background: To quantitatively and qualitatively assess vastus medialis muscle atrophy in asymptomatic patients with anterior cruciate ligament reconstruction, using the nonoperated leg as control. Methods: Prospective Institutional Review Board approved study with written informed patient consent. Thirty‐three asymptomatic patients (men, 21; women,12) with ACL‐reconstruction underwent MR imaging of both legs (axial T1‐weighted spin‐echo and 3D spoiled dual gradient‐echo sequences). Muscle volume and average fat‐signal fraction (FSF) of the vastus medialis muscles were measured. Additionally, Goutallier classification was used to classify fatty muscle degeneration. Significant side differences were evaluated using the Wilcoxon test and, between volumes and FSF, using student t‐tests with P‐value < 0.05 and < 0.025, respectively. Results: The muscle volume was significantly smaller in the operated (mean ± SD, 430.6 ± 119.6 cm3; range, 197.3 to 641.7 cm3) than in the nonoperated leg (479.5 ± 124.8 cm3; 261.4 to 658.9 cm3) (P < 0.001). Corresponding FSF was 6.3 ± 1.5% (3.9 to 9.2%) and 5.8 ± 0.9% (4.0 to 7.4%), respectively, with a nonsignificant (P > 0.025) difference. The relative muscle‐volume and FSF differences were −10.1 ± 8.6% (7.1 to −30.1%) and 10.9 ± 29.4% (39.7 to 40.1%). The qualitative assessment revealed no significant differences (P > 0.1). Conclusion: A significant muscle volume loss of the vastus medialis muscle does exist in asymptomatic patients with ACL‐reconstruction, but without fatty degeneration. J. Magn. Reson. Imaging 2015;42:515–525.

Cervical muscle area measurements in acute whiplash patients and controls

To quantitatively compare the muscle cross‐sectional areas (CSAs) of the cervical muscles in symptomatic acute whiplash patients versus healthy controls. We hypothesized, that symptomatic whiplash patients have smaller cervical muscle CSAs than matched controls and that smaller cervical muscle CSAs in women might explain that women more frequently are symptomatic after whiplash injury than men.