Objective
To evaluate the impact of magnetic resonance neurography (MRN) on diagnostic thinking and therapeutic choices in patients with suspected peripheral neuropathy.
Methods
IRB approval was ...obtained for this HIPAA-compliant study. Questionnaires were administered to six surgeons regarding the diagnosis and treatment in 85 patients suspected of having peripheral neuropathy, before (pretest) and after (posttest) MRN. Multiple outcome measures related to diagnostic confidence and surgical decision-making were assessed.
Results
The final cohort included 81 patients (30 men and 51 women, age 47 ± 17 years). The following changes were observed from pretest to posttest questionnaires: 23 % in nerve involvement (
P
< 0.05), 48 % in degree of confidence of nerve involvement (
P
< 0.01), 27 % in grade of injury (
P
< 0.05), 33 % in differential diagnosis (
P
< 0.05), 63 % in degree of confidence in need for surgery (
P
< 0.001), 41 % in timing of surgery (
P
< 0.01), 30 % in approach to surgery (
P
< 0.05), 58 % in degree of confidence in approach to surgery (
P
< 0.001), 30 % in estimated length of surgery (
P
< 0.05) and 27 % in length of incision (
P
< 0.05). The dichotomous decision regarding surgical or nonsurgical treatment changed from pro to con in 17 %.
Conclusion
MRN results significantly influenced the diagnostic thinking and therapeutic recommendations of peripheral nerve surgeons.
Key Points
• In patients with peripheral neuropathy, MRN significantly impacts diagnostic thinking.
• In patients with peripheral neuropathy, MRN significantly impacts therapeutic choices.
• 3-T MRN should be considered in presurgical planning of patients with peripheral neuropathy.
The aim of this study was to prospectively test the hypothesis that 6-fold acceleration of a 3-dimensional (3D) turbo spin echo (TSE) magnetic resonance imaging (MRI) pulse sequence with k-space ...undersampling and iterative reconstruction is feasible for fast high spatial resolution MRI of the knee, while yielding similar image quality and diagnostic performance when compared with a conventional 2-dimensional (2D) TSE MRI standard.
The study was approved by the institutional review board. A 10-minute isotropic 3D TSE knee protocol consisting of accelerated intermediate-weighted (repetition time, 900 milliseconds; echo time, 29 milliseconds; voxel size, 0.5 × 0.5 × 0.5 mm; acquisition time, 4:45 minutes) and fat-saturated T2-weighted (repetition time, 900 milliseconds; echo time, 92 milliseconds; voxel size, 0.5 × 0.5 × 0.5 mm; acquisition time, 5:10 minutes) SPACE (sampling perfection with application optimized contrast using different flip angle evolutions) sequence prototypes was compared against a 20-minute 2D TSE standard protocol. The accelerated SPACE sequences were equipped with an optional variable-density poisson-disc pattern as an undersampling mask. An undersampling factor of 0.17 was chosen (6-fold acceleration compared with an acquisition with full sampling). An iterative, sensitivity encoding-type reconstruction with L1 norm-based regularization term was used. The study was performed on a 3 T MRI system using a 15-channel transmit/receive knee coil. The study groups included 15 asymptomatic volunteers and 15 patient volunteers. Quantitative and qualitative assessments were performed by 2 observers. Outcome variables included signal and contrast-to-noise ratio, image quality, and diagnostic accuracy. Qualitative and quantitative measurements were statistically analyzed using nonparametric tests. P values of less than 0.01 were considered significant.
The signal-to-noise ratios of 2D and 3D MRI were similar with the exception of fluid, which was brighter on 2D MRI. Relevant contrast-to-noise ratios of 2D MRI were higher than 3D MRI; however, observer ratings for satisfaction, image quality, and visibility of anatomic structures were similar for 2D and 3D MRI. There was moderate to excellent interobserver (κ = 0.54-1.00) and intermethod (κ = 0.54-1.00) agreement for assessing menisci, cartilage, ligaments, cartilage, and bone. Two-dimensional and 3D MRI had similar sensitivity (100%/100%, respectively) and specificity (87%/75%, respectively) for detecting 9 meniscal tears (P = 1.00).
We demonstrate the successful clinical implementation of 3D TSE MRI with incoherent k-space undersampling and iterative reconstruction for 6-fold accelerated high spatial resolution isotropic 3D MRI data acquisition. Our preliminary assessments suggest similar image quality and diagnostic performance of a comprehensive 10-minute 3D TSE MRI prototype protocol and 20-minute TSE MRI standard protocol.
The aim of this study was to prospectively test the hypothesis that a compressed sensing-based slice encoding for metal artifact correction (SEMAC) turbo spin echo (TSE) pulse sequence prototype ...facilitates high-resolution metal artifact reduction magnetic resonance imaging (MRI) of cobalt-chromium knee arthroplasty implants within acquisition times of less than 5 minutes, thereby yielding better image quality than high-bandwidth (BW) TSE of similar length and similar image quality than lengthier SEMAC standard of reference pulse sequences.
This prospective study was approved by our institutional review board. Twenty asymptomatic subjects (12 men, 8 women; mean age, 56 years; age range, 44-82 years) with total knee arthroplasty implants underwent MRI of the knee using a commercially available, clinical 1.5 T MRI system. Two compressed sensing-accelerated SEMAC prototype pulse sequences with 8-fold undersampling and acquisition times of approximately 5 minutes each were compared with commercially available high-BW and SEMAC pulse sequences with acquisition times of approximately 5 minutes and 11 minutes, respectively. For each pulse sequence type, sagittal intermediate-weighted (TR, 3750-4120 milliseconds; TE, 26-28 milliseconds; voxel size, 0.5 × 0.5 × 3 mm) and short tau inversion recovery (TR, 4010 milliseconds; TE, 5.2-7.5 milliseconds; voxel size, 0.8 × 0.8 × 4 mm) were acquired. Outcome variables included image quality, display of the bone-implant interfaces and pertinent knee structures, artifact size, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Statistical analysis included Friedman, repeated measures analysis of variances, and Cohen weighted k tests. Bonferroni-corrected P values of 0.005 and less were considered statistically significant.
Image quality, bone-implant interfaces, anatomic structures, artifact size, SNR, and CNR parameters were statistically similar between the compressed sensing-accelerated SEMAC prototype and SEMAC commercial pulse sequences. There was mild blur on images of both SEMAC sequences when compared with high-BW images (P < 0.001), which however did not impair the assessment of knee structures. Metal artifact reduction and visibility of central knee structures and bone-implant interfaces were good to very good and significantly better on both types of SEMAC than on high-BW images (P < 0.004). All 3 pulse sequences showed peripheral structures similarly well. The implant artifact size was 46% to 51% larger on high-BW images when compared with both types of SEMAC images (P < 0.0001). Signal-to-noise ratios and CNRs of fat tissue, tendon tissue, muscle tissue, and fluid were statistically similar on intermediate-weighted MR images of all 3 pulse sequence types. On short tau inversion recovery images, the SNRs of tendon tissue and the CNRs of fat and fluid, fluid and muscle, as well as fluid and tendon were significantly higher on SEMAC and compressed sensing SEMAC images (P < 0.005, respectively).
We accept the hypothesis that prospective compressed sensing acceleration of SEMAC is feasible for high-quality metal artifact reduction MRI of cobalt-chromium knee arthroplasty implants in less than 5 minutes and yields better quality than high-BW TSE and similarly high quality than lengthier SEMAC pulse sequences.
The 3-dimensional nature of adult acquired flatfoot deformity can be challenging to characterize using radiographs. We tested the hypothesis that measurements on weight-bearing (WB) cone-beam ...computed tomography (CT) images were more useful for demonstrating the severity of the deformity than non-weight-bearing (NWB) measurements.
We prospectively enrolled 12 men and 8 women (mean age, 52 years; range, 20 to 88 years) with flexible adult acquired flatfoot deformity. The subjects underwent cone-beam CT while standing (WB) and seated (NWB), and images were assessed in the sagittal, coronal, and axial planes by 3 independent observers who performed multiple measurements. Intraobserver and interobserver reliabilities were assessed with the Pearson or Spearman correlation and the intraclass correlation coefficient (ICC), respectively. Measurements were compared using paired Student t tests or Wilcoxon rank-sum tests. P < 0.05 was considered significant.
We found that overall the measurements had substantial intraobserver and interobserver reliability on both the NWB images (mean ICC, 0.80; range, 0.49 to 0.99) and the WB images (mean ICC, 0.81; range, 0.39 to 0.99). Eighteen of 19 measurements differed between WB and NWB cone-beam CT images, with more pronounced deformities on the WB images. The most reliable measurements, based on intraobserver and interobserver reliabilities and the difference between WB and NWB images, were the medial cuneiform-to-floor distance, which averaged 29 mm (95% confidence interval CI = 28 to 31 mm) on the NWB images and 18 mm (95% CI = 17 to 19 mm) on the WB images, and the forefoot arch angle (mean, 13° 95% CI = 12° to 15° and 3.0° 95% CI = 1.4° to 4.6°, respectively) in the coronal view and the cuboid-to-floor distance (mean, 22 mm 95% CI = 21 to 23 mm and 17 mm 95% CI = 16 to 18 mm, respectively) and the navicular-to-floor distance (mean, 38 mm 95% CI = 36 to 40 mm and 23 mm 95% CI = 22 to 25 mm, respectively) in the sagittal view.
Measurements analogous to traditional radiographic parameters of adult acquired flatfoot deformity are obtainable using high-resolution cone-beam CT. Compared with NWB images, WB images better demonstrated the severity of osseous derangement in patients with flexible adult acquired flatfoot deformity.
Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.
Background
Ten‐minute MRI of the pediatric knee can add value through increased cost‐effectiveness and decreased sedation needs but requires validation of its clinical efficacy.
Purpose
To determine ...the arthroscopy‐based diagnostic accuracy and interreader reliability of 10‐min 3D Controlled Aliasing In Parallel Imaging Results In Higher Acceleration (CAIPIRINHA) turbo spin echo (TSE) MRI with two isotropic pulse sequences for the diagnosis of internal derangement in children with painful knee conditions.
Study Type
Prospective.
Subjects
Sixty children.
Field Strength/Sequence
3T, gradient echo‐based scout with automatic anatomical landmark recognition and plane prescription, 3D CAIPIRINHA SPACE TSE.
Assessment
Three fellowship‐trained musculoskeletal radiologists evaluated the MRI studies independently and resolved discrepancies through consensus. Outcome variables included image quality, motion artifacts, meniscal abnormalities, anterior and posterior cruciate ligament tears, and cartilage lesions. Arthroscopic surgery served as the standard of reference, which was performed after 37 (range, 1–143) days post‐MRI.
Statistical Tests
Diagnostic accuracy analysis of MRI with arthroscopic surgery as the standard of reference. Reliability analysis through calculation of interreader agreements with kappa statistics.
Results
All studies were suitable for diagnostic interpretation with good‐to‐very‐good image quality ratings and little‐to‐no motion degradation ratings in the majority of cases. The sensitivities/specificities/accuracies of 3D CAIPIRINHA TSE MRI were 0.93/0.96/0.94 for 15/60 (25%) medial meniscal tears, 0.95/0.92/0.94 for 21/60 (35%) lateral meniscal tears, 0.83/1.00/0.92 for 6/60 (17%) discoid menisci, 1.00/0.98/0.99 for 16/60 (27%) anterior cruciate ligament tears, 1.0/1.0/1.0 for 2/60 (3%) posterior cruciate ligament tears, 1.00/1.00/1.00 for 5/60 (8%) osteochondritis dissecans lesions, 0.71/0.96/0.84 for 48 (13%) defects in 360 cartilage segments, and 0.85/0.97/0.91 overall. The interreader agreements were overall good‐to‐very‐good (kappa, 0.72–1.00).
Data Conclusion
The clinical use of 10‐min 3D CAIPIRINHA TSE MRI of the knee in children with painful knee conditions yields an overall high arthroscopy‐validated diagnostic accuracy of 91% and good‐to‐very good interreader reliability for the diagnosis of internal knee derangements.
Level of Evidence: 1
Technical Efficacy: Stage 6
J. Magn. Reson. Imaging 2019;49:e139–e151.
We prospectively quantified the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of integrated parallel acquisition technique (PAT) and simultaneous multislice (SMS) acceleration and ...various combinations thereof, and we further compared two 4-fold-accelerated (PAT2-SMS2) high-resolution turbo spin echo (TSE) magnetic resonance imaging (MRI) protocols of the knee against a clinical 2-fold-accelerated (PAT2-SMS1) TSE standard.
Institutional review board approval was obtained, and all subjects gave informed consent. Fourteen knee MRI examinations were obtained (8 men, 6 women; mean age, 46 years; age range, 28-62 years) using a 3 T MRI system and a TSE pulse sequence prototype that allowed for the combination of PAT and SMS acceleration. Predicted whole-body specific absorption rates were recorded for all pulse sequences. For quantitative analysis, the difference method was used to calculate SNR and CNR analysis of 6 different TSE acceleration schemes (PAT2-SMS1, PAT3-SMS1, PAT1-SMS2, PAT1-SMS3, PAT2-SMS2, and PAT2-SMS3). For qualitative analysis, sagittal intermediate-weighted and axial fat-suppressed T2-weighted MR images were obtained with PAT2-SMS1 and PAT2-SMS2 acceleration schemes using similar parameters. One faster PAT2-SMS2 acceleration scheme with decreased repetition time and longer echo train was labeled with the addition SPEED for the purpose of this report. Two readers rated the data sets for image quality, structural visibility, and overall observer satisfaction using equidistant 5-point Likert scales. Readers additionally noted the presence of cartilage defects, meniscal tears, tendons and ligament tears, and bone marrow edema pattern. Friedman and Kruskal-Wallis tests were used. P values of less than 0.01 were considered significant.
All pulse sequences were successfully executed and reconstructed inline. Whole-body specific absorption rates ranged between 1.4 and 3.9 W/kg for all acquisitions and remained within mandated limits. Quantitatively, mean SNR and CNR were significantly higher for SMS than those for PAT and similar for PAT2-SMS2 and PAT2-SMS1. Fluid was brightest on PAT2-SMS1, whereas noise, edge sharpness, contrast resolution, and fat suppression were similar on PAT2-SMS1 and SMS2-PAT2 and mildly inferior on PAT2-SMS2 SPEED. Articular cartilage received mildly higher ratings on PAT2-SMS1, whereas visibility of menisci was mildly inferior on PAT2-SMS2 SPEED. Observer preferences were similarly high for PAT2-SMS1 and PAT2-SMS2 and mildly inferior for the faster PAT2-SMS2 SPEED images. Four cartilage defects and 2 meniscal tears were seen by both readers on all sequences.
We demonstrate the signal preservation capabilities of SMS over PAT acceleration, which allow for similar SNR and CNR of 4-fold PAT2-SMS2 and 2-fold PAT2-SMS1 acceleration. Four-fold-accelerated TSE through the combination of PAT2 and SMS2 enables approximately 50% shorter acquisition times compared with regular PAT2 acceleration, similar quantitative and qualitative image quality, and holds promise for a meaningful increase of the efficiency of clinical 2-dimensional MRI of the knee.
Objectives
To test the hypothesis that MRI of the ankle with a 10-min 3D CAIPIRINHA SPACE TSE protocol is at least equivalent for the detection of painful conditions when compared to a 20-min 2D TSE ...standard of reference protocol.
Methods
Following institutional review board approval and informed consent, 70 symptomatic subjects underwent 3T MRI of the ankle. Six axial, sagittal and coronal intermediate-weighted (IW) and fat-saturated T2-weighted (T2FS) 2D TSE (total acquisition time, 20 min), and two sagittal isotropic IW and T2FS 3D CAIPIRINHA TSE (10 min) pulse sequence prototypes were obtained. Following randomization and anonymization, two musculoskeletal radiologists evaluated the 2D and 3D datasets independently. Descriptive statistics, inter-reader reliability, inter-method concordance, diagnostic definitiveness tests were applied.
P
-values < 0.05 were considered significant.
Results
Raters diagnosed 116 cartilage defects with 2D and 109 with 3D MRI, 35 ligament tears with 2D and 65 with 3D MRI, 18 tendon tears with 2D and 20 with 3D MRI, and 137 osseous abnormalities with 2D and 149 with 3D MRI. The inter-reader agreement was high for 2D (Kendall W, 0.925) and 3D MRI (W, 0.936) (
p
< 0.05), as was the inter-method concordance (W, 0.919). The diagnostic definitiveness of readers was higher for 3D MRI than 2D MRI in 10-27% of the time, while the reverse was true in 7-11% of the time (
p
< 0.01).
Conclusions
The performance of 10-min 3D CAIPIRINHA SPACE MRI for the detection of painful ankle conditions is similar to that of a 20-min 2D TSE MRI reference standard.
Key Points
• CAIPIRINHA Acceleration facilitates isotropic 3D MRI of the Ankle in 10 min.
• 10-min 3D CAIPIRINHA MRI and 20-min 2D TSE MRI have similar performance.
• 3D CAIPIRINHA SPACE MRI afforded higher diagnostic definitiveness of readers.
The lumbosacral plexus comprises a network of nerves that provide motor and sensory innervation to most structures of the pelvis and lower extremities. It is susceptible to various traumatic, ...inflammatory, metabolic, and neoplastic processes that may lead to lumbrosacral plexopathy, a serious and often disabling condition whose course and prognosis largely depend on the identification and cure of the causative condition. Whereas diagnosis of lumbrosacral plexopathy has traditionally relied on patients' medical history, clinical examination, and electrodiagnostic tests, magnetic resonance (MR) neurography plays an increasingly prominent role in noninvasive characterization of the type, location, and extent of lumbrosacral plexus involvement and is developing into a useful diagnostic tool that substantially affects disease management. With use of 3-T MR imagers, improved coils, and advanced imaging sequences, which provide exquisite spatial resolution and soft-tissue contrast, MR neurography provides excellent depiction of the lumbrosacral plexus and its peripheral branches and may be used to confirm a diagnosis of lumbrosacral plexopathy with high accuracy or provide superior anatomic information should surgical intervention be necessary.
Purpose To evaluate the role of tibial tuberosity–trochlear groove (TT-TG) distance in patellofemoral kinematics by retrospectively reviewing the dynamic computed tomography scans of patients with ...unilateral patellofemoral instability and comparing unstable and contralateral asymptomatic knees. Methods We reviewed all dynamic computed tomography scans obtained at one tertiary care hospital from 2008 through 2013 and identified 25 patients with a history of recurrent unilateral patellofemoral instability. During the scans, subjects performed active knee extension against gravity. Both knees were imaged simultaneously. Lateral patellar tilt (LPT) and bisect offset (BO) were measured to assess tracking. TT-TG distance was measured to assess alignment. Measurements were made in full extension, maximum flexion, and approximately 10° increments in between. The significance level was set at P < .05. Results LPT, BO, and TT-TG distance were highest in extension and decreased with flexion. Measurements were higher in symptomatic than in asymptomatic knees, with significant differences identified for LPT, BO, and TT-TG distance at 5° and 15° and for TT-TG distance at 25° and 35° ( P < .05). TT-TG distance was associated with LPT and BO, with r2 values in symptomatic knees of 0.55 for TT-TG distance and LPT and of 0.45 for TT-TG distance and BO. Conclusions In patients with unilateral patellar instability, LPT, BO, and TT-TG distance are higher on the unstable side. An association exists between TT-TG distance and the tracking parameters studied, suggesting that TT-TG distance relates to patellar tracking, and a laterally positioned tibial tuberosity may predispose to instability episodes. Level of Evidence Level IV, diagnostic study.
Objectives
To evaluate the improvement in extremity cone-beam computed tomography (CBCT) image quality in datasets with motion artifact using a motion compensation method based on maximizing image ...sharpness.
Methods
Following IRB approval, retrospective analysis of 308 CBCT scans of lower extremities was performed by a fellowship-trained musculoskeletal radiologist to identify images with moderate to severe motion artifact. Twenty-four scans of 22 patients (18 male, four female; mean, 32 years old, range, 21–74 years old) were chosen for inclusion. Sharp (bone) and smooth (soft tissue) reconstructions were processed using the motion compensation algorithm. Two experts rated visualization of trabecular bone, cortical bone, joint spaces, and tendon on a nine-level Likert scale with and without motion compensation (a total of 96 datasets). Visual grading characteristics (VGC) was used to quantitatively determine the difference in image quality following motion compensation. Intra-class correlation coefficient (ICC) was obtained to assess inter-observer agreement.
Results
Motion-compensated images exhibited appreciable reduction in artifacts. The observer study demonstrated the associated improvement in diagnostic quality. The fraction of cases receiving scores better than “Fair” increased from less than 10% without compensation to 40–70% following compensation, depending on the task. The area under the VGC curve was 0.75 (tendon) to 0.85 (cortical bone), confirming preference for motion compensated images. ICC values showed excellent agreement between readers before (ICC range, 0.8–0.91) and after motion compensation (ICC range, 0.92–0.97).
Conclusions
The motion compensation algorithm significantly improved the visualization of bone and soft tissue structures in extremity CBCT for cases exhibiting patient motion.
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