Diagnostic performance of a 3D double-echo steady-state sequence at 3 T using radial reformats for detecting and grading rotator cuff tears: a pilot diagnostic accuracy study with magnetic resonance imaging and arthroscopic correlation.

BACKGROUND: In diagnosing rotator cuff tears (RCTs), magnetic resonance imaging (MRI) is the imaging modality of choice, and its accuracy is improving constantly. PURPOSE: To evaluate the diagnostic performance of a high-resolution 3D double-echo steady-state (DESS) sequence with radial and paracoronal 3-T MRI regarding the grading of RCTs in correlation with conventional 2D MRI and arthroscopic findings. MATERIAL AND METHODS: We retrospectively compared arthroscopic findings of RCTs with preoperative MRI, including conventional 2D sequences and radial and paracoronal DESS images in 20 patients. Two observers evaluated supraspinatus (SSP), infraspinatus (ISP), and subscapularis (SSC) tendon tears using a grading system. For statistical analysis, arthroscopy was used as the reference standard. RESULTS: Inter-observer agreement for detecting and grading SSP, ISP, and SSC tendon tears on radial and paracoronal sliced 3D DESS MRI was excellent (intraclass-correlation [ICC] = 0.92-0.98; all P < 0.001). Regarding the detection of SSP lesions, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 93.8%, 50%, 88.2%, and 66.7% for both radial and paracoronal DESS imaging. A sensitivity of 100%, specificity of 61.1%, PPV of 22.2%, and NPV of 100% were noted for detecting ISP tendon tears using radially reformatted DESS images. Regarding detecting SSC tendon tears using radially reformatted DESS images, sensitivity, specificity, PPV, and NPV were 100%, 81.3%, 50%, and 100%, respectively. The results with standard 2D MRI were similar. CONCLUSION: The DESS technique with radially reformatted images provided excellent sensitivity and high inter-observer agreement in detecting RCTs. It showed a moderate to high correlation between MRI and arthroscopy for diagnosing SSP and SSC tendon tears.

The influence of distribution, severity and volume of posttraumatic bone bruise on functional outcome after ACL reconstruction for isolated ACL injuries.

INTRODUCTION: Posttraumatic MRI of ACL tears show a high prevalence of bone bruise (BB) without macroscopic proof of chondral damage. Controversial results are described concerning the association between BB and outcome after ACL tear. Aim of this study is to evaluate the influence of distribution, severity and volume of BB in isolated ACL injuries on function, quality of life and muscle strength following ACL reconstruction (ACLR). MATERIALS AND METHODS: MRI of n = 122 patients treated by ACLR without concomitant pathologies were evaluated. BB was differentiated by four localizations: medial/lateral femoral condyle (MFC/LFC) and medial/lateral tibial plateau (MTP/LTP). Severity was graded according to Costa-Paz. BB volumes of n = 46 patients were quantified (software-assisted volumetry). Outcome was measured by Lysholm Score (LS), Tegner Activity Scale (TAS), IKDC, isokinetics and SF-36. Measurements were conducted preoperatively (t0), 6 weeks (t1), 26 weeks (t2) and 52 weeks (t3) after ACLR. RESULTS: The prevalence of BB was 91.8%. LTP was present in 91.8%, LFC 64.8%, MTP 49.2% and MFC 28.7%. 18.9% were classified Costa-Paz I, 58.2% II and 14.8% III. Total BB volume was 21.84 ± 15.27 cm3, the highest value for LTP (14.31 ± 9.93 cm3). LS/TAS/IKDC/SF-36/isokinetics improved significantly between t0-t3 (p < 0.001). Distribution, severity and volume had no influence on LS/TAS/IKDC/SF-36/isokinetics (n.s.). CONCLUSIONS: No impact of BB after ACLR on function, quality of life and objective muscle strength was shown, unaffected by concomitant pathologies. Previous data regarding prevalence and distribution is confirmed. These results help surgeons counselling patients regarding the interpretation of extensive BB findings. Long-time follow-up studies are mandatory to evaluate an impact of BB on knee function due to secondary arthritis.

Sodium MRI of human articular cartilage of the wrist: a feasibility study on a clinical 3T MRI scanner.

OBJECTIVE: To measure sodium relaxation times and concentrations in human wrists on a clinical magnetic resonance imaging (MRI) scanner with a density-adapted radial sequence. MATERIALS AND METHODS: Sodium MRI of human wrists was conducted on a 3T MR system using a dual-tuned 1H/23Na surface coil. We performed two studies with 10 volunteers each investigating either sodium T1 (study 1) or sodium T2* (study 2) relaxation times in the radiocarpal joint (RCJ) and midcarpal joint (MCJ). Sodium concentrations of both regions were determined. RESULTS: No differences for transversal of longitudinal relaxation times were found between RCJ and MCJ (T2,s*(RCJ) = (0.9 ± 0.4) ms; T2,s*(MCJ) = (0.9 ± 0.3) ms; T2,l*(RCJ) = (14.9 ± 0.9) ms; T2,l*(MCJ) = (13.9 ± 1.1) ms; T1(RCJ) = (19.0 ± 2.4) ms; T1(MCJ) = (18.5 ± 2.1) ms). Sodium concentrations were (157.7 ± 28.4) mmol/l for study 1 and (159.8 ± 29.1) mmol/l for study 2 in the RCJ, and (172.7 ± 35.6) mmol/l for study 1 and (163.4 ± 26.3) mmol/l for study 2 in the MCJ. CONCLUSION: We successfully determined sodium relaxation times and concentrations of the human wrist on a 3T MRI scanner.

Detection of early cartilage degeneration in the tibiotalar joint using 3 T gagCEST imaging: a feasibility study.

OBJECTIVE: To establish and optimize a stable 3 Tesla (T) glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging protocol for assessing the articular cartilage of the tibiotalar joint in healthy volunteers and patients after a sustained injury to the ankle. METHODS: Using Bloch-McConnell simulations, we optimized the sequence protocol for a 3 T MRI scanner for maximum gagCEST effect size within a clinically feasible time frame of less than 07:30 min. This protocol was then used to analyze the gagCEST effect of the articular cartilage of the tibiotalar joint of 17 healthy volunteers and five patients with osteochondral lesions of the talus following ankle trauma. Reproducibility was tested with the intraclass correlation coefficient. RESULTS: The mean magnetization transfer ratio asymmetry (MTRasym), i.e., the gagCEST effect size, was significantly lower in patients than in healthy volunteers (0.34 ± 1.9% vs. 1.49 ± 0.11%; p < 0.001 [linear mixed model]). Intra- and inter-rater reproducibility was excellent with an average measure intraclass correlation coefficient (ICC) of 0.97 and a single measure ICC of 0.91 (p < 0.01). DISCUSSION: In this feasibility study, pre-morphological tibiotalar joint cartilage damage was quantitatively assessable on the basis of the optimized 3 T gagCEST imaging protocol that allowed stable quantification gagCEST effect sizes across a wide range of health and disease in clinically feasible acquisition times.

Differentiating rheumatoid and psoriatic arthritis: a systematic analysis of high-resolution magnetic resonance imaging features-preliminary findings.

BACKGROUND: Because of overlapping phenotypical presentations, the diagnostic differentiation of rheumatoid arthritis (RA) and psoriatic arthritis (PsA) remains challenging. Thus, this study aimed to examine the diagnostic value of distinct imaging features obtained by high-resolution 3-T MRI for the diagnostic differentiation. MATERIALS AND METHODS: Seventeen patients with PsA and 28 patients with RA were imaged at high resolution using 3-T MRI scanners and a dedicated 16-channel hand coil. All images were analyzed according to the outcome measures in rheumatology clinical trials' (OMERACT) RAMRIS (Rheumatoid Arthritis Magnetic Resonance Imaging Score) and PsAMRIS (Psoriatic Arthritis Magnetic Resonance Imaging Score) for the presence and intensity of synovitis, flexor tenosynovitis, bone edema, bone erosion, periarticular inflammation, bone proliferation, and joint space narrowing. Next, odds ratios (OR) were calculated to determine the strength of the associations between these imaging features, demographic characteristics, and the outcome RA vs. PsA. RESULTS: PsA could be differentiated from RA by extracapsular inflammatory changes (PsAMRIS sub-score "periarticular inflammation"), with low odds for the presence of RA (OR of 0.06, p < 0.01) at all metacarpophalangeal (MCP) joints. A prediction model informed by the items that were strongest associated with the presence of RA or PsA demonstrated excellent differentiating capability with an area under the curve of 98.1%. CONCLUSION: High-resolution imaging is beneficial for the identification of relevant imaging features that may assist the clinical differentiation of inflammatory conditions of the hand. At the MCP level, extracapsular inflammatory changes were strongly associated with PsA and may consequently allow the imaging differentiation of PsA and RA.

Assessment of Articular Cartilage Disorders After Distal Radius Fracture Using Biochemical and Morphological Nonenhanced Magnetic Resonance Imaging.

PURPOSE: To assess radiocarpal articular cartilage after distal radius fracture, with and without intra-articular extension, compared with healthy controls using multiparametric, nonenhanced magnetic resonance imaging (MRI). METHODS: In this prospective study, multiparametric MRI of the radiocarpal articular cartilage was performed in 26 participants (16 males and 10 females; mean age, 39.5 ± 14.7 years; range, 20-70 years) using 3T MRI. The cohort consisted of 14 patients with a distal radius fracture and 12 healthy volunteers. The radiocarpal articular cartilage was assessed using morphological (Double Echo Steady-State [DESS] and True Fast Imaging With Steady-State Precession [TrueFISP]) and biochemical (T2∗) MRI sequences without an intravenous contrast agent. The modified Outerbridge classification system for morphological analyses and region-of-interest biochemical analysis were applied to assess the degree of articular cartilage damage in each patient. RESULTS: Morphological articular cartilage assessment showed no difference between the DESS sequence and the reference standard, TrueFISP. In the morphological (DESS and TrueFISP) and biochemical (T2∗) assessments, patients with intra-articular fractures did not show articular cartilage damage different from those with extra-articular fractures. Greater articular cartilage degradation was observed after distal radius fracture compared with controls. CONCLUSIONS: Posttraumatic radiocarpal articular cartilage damage did not differ between fractures with intra-articular and extra-articular extension, but patients with fractures had notably higher articular cartilage degradation compared with healthy controls. Magnetic resonance imaging using advanced multiparametric sequences may facilitate accurate, noninvasive assessment of articular cartilage changes after distal radius fracture without the need for a contrast agent. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic IV.

Prospective comparison of whole-body MRI and 68Ga-PSMA PET/CT for the detection of biochemical recurrence of prostate cancer after radical prostatectomy.

PURPOSE: To assess whole-body magnetic resonance imaging (wb-MRI) for detection of biochemical recurrence in comparison to 68Ga-prostate-specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT) in prostate cancer (Pca) patients after radical prostatectomy. METHODS: This was a prospective trial including 28 consecutive patients (mean age 65.3 ± 9.0 years) with newly documented biochemical recurrence of Pca (mean prostate-specific antigen, PSA, 2.09 ± 1.95 ng/ml) following radical prostatectomy. All patients underwent both wb-MRI including a dedicated pelvic imaging protocol and PET/CT with 166 ± 35 MBq 68Ga-PSMA within a time window of 11 ± 10 days. PET/CT and MRI datasets were separately evaluated regarding Pca lesion count, type, localization and diagnostic confidence (three-point Likert scale, 1-3) by two nuclear medicine specialists and two radiologists, respectively. The reference standard was based on histopathological results, PSA levels following targeted salvage irradiation and follow-up imaging. Lesion-based and patient-based detection rates were compared using the chi-squared test. Differences in diagnostic confidence were assessed using the Welch test. RESULTS: A total of 56 Pca lesions were detected in 20 of the 28 patients. 68Ga-PSMA PET/CT detected 56 of 56 lesions (100%) in 20 patients (71.4%), while wb-MRI detected 13 lesions (23.2%) in 11 patients (39.3%). The higher detection rate with 68Ga-PSMA PET/CT was statistically significant on both a per-lesion basis (p < 0.001) and a per-patient basis (p = 0.0167). In 8 patients (28.6%) no relapse was detectable by either modality. All lesions detected by wb-MRI were also detected by 68Ga-PSMA PET/CT. Additionally, 68Ga-PSMA PET/CT provided superior diagnostic confidence in identifying Pca lesions (2.7 ± 0.7 vs. 2.3 ± 0.6, p = 0.044). CONCLUSION: 68Ga-PSMA PET/CT significantly out-performed wb-MRI in the detection of biochemical recurrence in Pca patients after radical prostatectomy.

MRI identifies biochemical alterations of intervertebral discs in patients with low back pain and radiculopathy.

KEY POINTS: • Molecular intervertebral disc damage was associated with LBP and radiculopathy.• Patients with radiculopathy and LBP demonstrated a depletion of gagCEST values compared with healthy controls.• GagCEST imaging may be a non-invasive tool for investigation of degeneration processes of lumbar intervertebral discs (IVDs). GagCEST imaging may be an imaging biomarker for biochemical IVD alterations.

Differences of radiocarpal cartilage alterations in arthritis and osteoarthritis using morphological and biochemical magnetic resonance imaging without gadolinium-based contrast agent administration.

OBJECTIVES: To identify differences of radiocarpal cartilage alterations in osteoarthritis and arthritis using multiparametrical magnetic resonance imaging (MRI) comprising morphological and biochemical sequences without gadolinium-based contrast agent administration. METHODS: In this prospective study, multiparametrical MRI of the radiocarpal cartilage was performed in 47 participants (mean age, 46.6 ± 17.6 years; min., 20 years; max., 79 years) on a 3 Tesla MRI. The cohort consisted of 11 patients suffering from arthritis, 10 patients with osteoarthritis, 14 patients after distal radius fracture, and 12 healthy volunteers. The radiocarpal cartilage was assessed using morphological (DESS, TrueFISP) and biochemical (T2*) MRI sequences without the application of intravenous contrast agent. The modified Outerbridge classification system for morphological and region-of-interest analyses for biochemical analysis was applied to assess the degree of cartilage damage in each patient before data were statistically tested for significant difference between the groups using a post hoc Tukey test. RESULTS: In morphological imaging, cartilage damage was significantly more frequent in arthritis and osteoarthritis than in healthy volunteers (DESS: p = 0.01, p = 0.0004; TrueFISP: p = 0.02, p = 0.0001). In T2* imaging, patients with osteoarthritis showed higher cartilage damage compared to patients with arthritis (p = 0.01). CONCLUSION: With multiparametrical MRI, it is possible to identify differences of radiocarpal cartilage alterations of patients with arthritis and osteoarthritis using the combination of morphological and biochemical MR imaging of the radiocarpal cartilage without the application of contrast agent. Multiparametrical MRI without the usage of contrast agent may be a potential tool helping to distinguish both entities. KEY POINTS: • Multiparametrical MRI with morphological and biochemical sequences allows the differentiation of patients with arthritis and osteoarthritis. • High-resolution MRI of radiocarpal cartilage is possible without administration of contrast agent.

Prevention of the progressive biochemical cartilage destruction under methotrexate therapy in early rheumatoid arthritis.

OBJECTIVES: The aim of the study was to investigate biochemical cartilage composition under methotrexate (MTX) therapy and to intra-individually assess the impact of inflammation severity on cartilage composition by using dGEMRIC MRI in patients with early rheumatoid arthritis (eRA). METHODS: dGEMRIC of MCP joints of the index and middle finger of 28 patients from the AthroMark cohort were examined prior to MTX-therapy as well as after 3 and 6 month. OMERACT RA MRI score and clinical parameters (CRP and DAS28) were registered at any time point. Each patient's second and third MCP joints were dichotomised into the joint with more severe synovitis versus the joint with less severe synovitis according to the RAMRIS synovitis subscore. RESULTS: MCP joints with more severe synovitis ('bad joints') demonstrated significantly lower dGEMRIC values compared to MCP joints with less severe synovitis ('good joints') at time-points 0 and 3 months (p=0.002; p=0.019, respectively). After 6 months of MTX therapy no significant difference of dGEMRIC index was found between good and bad joint (p=0.086). CONCLUSIONS: Under MTX therapy, biochemical cartilage integrity remains stable; no further cartilage destruction occurred if patients were treated early in the course of the disease. In addition, six months of MTX therapy triggered an alignment of dGEMRIC index of MCP joints with initially severe synovitis and less severe synovitis in an intra-individual assessment. This underlines the importance of an early treatment in eRA to reduce further cartilage damage of the inflamed joints.

Elite Rowers Demonstrate Consistent Patterns of Hip Cartilage Damage Compared With Matched Controls: A T2* Mapping Study.

BACKGROUND: Rowing exposes the femoral head and acetabulum to high levels of repetitive abutment motion and axial loading that may put elite athletes at an increased risk for developing early hip osteoarthritis. QUESTIONS/PURPOSES: Do elite rowers demonstrate characteristic hip cartilage lesions on T2 MRI sequences compared with asymptomatic individuals who do not row? METHODS: This study included 20 asymptomatic rowers (mean age, 23 ± 3 years; nine females, 11 males) who had a minimum of 5 years of intensive (≥ 12 hours/week) training. The recruiting of the rowers took place from the central German federal rowing base, which has inherent intense training and selection requirements to declare these athletes as "elite rowers." We investigated one hip per study participant. MRI was performed on a 3-T scanner. The protocol included standard sequences, a double-echo steady-state sequence, and a multiecho data image combination sequence with inline T2 calculation (= the decay of transverse magnetization arising from molecular interactions [T2] and inhomogeneities in the magnetic field resulting from tissue susceptibility-induced field distortions and variations in the magnet itself), which detects changes in water content and the disruption of collagen structure. Although extrinsic and intrinsic influences on the T2 values including diurnal effects, MR technic-derived variations, and anatomic-related regional disparities need to be taken into account, low T2 values well below 20 ms indicate cartilage degeneration. Cartilage was morphologically analyzed in the anterior, anterosuperior, superoanterior, superior, superoposterior, posterosuperior, and posterior regions of the hip and graded as follows: Grade 0 = normal; Grade 1 = signal changes; Grade 2 = cartilage abrasion; Grade 3 = cartilage loss. Labrum was classified as follows: Grade 0 = normal; Grade 1 = partial tear; Grade 2 = full-thickness tear; Grade 3 = labrum degeneration. The T2 measurement was done through a region of interest analysis. For reliability assessment, morphologic evaluation and T2 measurement were performed by two observers while one observer repeated his analysis with a time interval > 2 weeks. Intra- and interobserver reliability was determined using κ analysis and intraclass correlation coefficients. Control T2 data were derived from a previous study on 15 hips in 15 asymptomatic volunteers of similar ages (seven males and eight females) who were not competitive rowers with similar MR hardware and imaging sequences. RESULTS: Compared with the control group of asymptomatic volunteers who were not competitive rowers, we noted a high level of labrum and cartilage degeneration in the cohort of elite rowers. In the group of elite rowers, cartilage degeneration was noted in all hips. Regarding the acetabular cartilage, 271 zones could be evaluated. Of those, 44% (120 of 271) were graded normal, 6% (15 of 271) revealed signal alteration, 45% (122 of 271) demonstrated cartilage abrasion, and 5% (14 of 271) were noted to have full-thickness cartilage loss. Morphologic cartilage degeneration in the femoral head was less frequent. T2 values were lower than the control hips in all zones except for the posterior central acetabular zone (global T2 acetabular: 20 ± 6 ms, range, 9-36 ms, 95% confidence interval [CI], 19-21 ms versus 25 ± 5 ms, range, 14-44 ms, 95% CI, 24-25 ms, p < 0.001; global T2 femoral: 23 ± 7 ms, range, 9-38 ms, 95% CI, 22-24 ms versus 27 ± 5 ms, range, 17-45 ms, 95% CI, 26-28 ms, p < 0.001). The difference in T2 between the two study groups was superior in the peripheral zone of the anterosuperior region (16 ± 3 ms; range, 10-22 ms, 95% CI, 15-18 ms versus 26 ms ± 5 ms, range, 18-38 ms, 95% CI, 24-29 ms, p < 0.001). CONCLUSIONS: We found signs of hip cartilage degeneration to a much greater degree in elite rowers than in asymptomatic controls. Although causation cannot be inferred, this is concerning, and future investigations including controlled longitudinal studies both on elite and nonelite athletes with sufficient cohort size are warranted to clarify our findings. LEVEL OF EVIDENCE: Level III, therapeutic study.

Update on imaging in rheumatic diseases: cartilage.

In recent years, the role of articular cartilage for understanding pathogenesis as well as for clinical research has become increasingly important. Whereas previously cartilage could only be assessed invasively, various imaging procedures are available for its evaluation now. Although still widely used, conventional radiography bears significant limitations since it assesses cartilage indirectly by joint space width. Today, the cartilage thickness and structure can be reliably evaluated using ultrasound, although the molecular structure cannot be determined, yet. Besides ultrasound, MRI offers the possibility to image morphological changes with a very high resolution. In addition, the quality and composition of joint cartilage can already be measured due to a constant technical improvement and new MRI sequences such as dGEMRIC even in small joints (e.g. MCP or MTP joints). Despite the advantages of contrast agents for the detection of inflammation, its use is reevaluated today. Regarding that contrast agent-free imaging techniques for the assessment of joint cartilage are developed with great effort to depict its quality and changes over time. These novel MRI methods such as T2/T2*- and T1ρ-mapping, gagCEST, and sodium imaging provide promising quantitative imaging biomarkers that can detect early cartilage changes before morphological alterations occur. Hence, US and MRI will likely be of paramount importance in future clinical trials and clinical assessment of inflammatory and degenerative joint diseases not only for understanding pathogenesis but also for using its possible value in daily practice.

Cartilage Imaging: Techniques and Developments.

Cartilage degeneration is one of the most common chronic age-related joint disorders leading to pain and reduced joint motion. The increasing prevalence of osteoarthritis requires accurate cartilage imaging, both clinically and in research. Detailed cartilage imaging is also necessary for traumatic cartilage lesions and for pre- and postoperative assessment of cartilage repair procedures. Although still widely used, conventional radiography bears significant limitations because it assesses cartilage indirectly by joint space width. Magnetic resonance imaging (MRI) enables direct visualization of cartilage damage along with other concomitantly affected joint tissues. Several semiquantitative grading systems and volumetric analysis methods exist to assess cartilage damage and cartilage repair on MRI. Quantification of hyaline and fibrocartilage biochemical composition is possible with novel MRI methods such as T2- and T1ρ-mapping, delayed gadolinium-enhanced MRI of cartilage, glycosaminoglycan chemical exchange saturation transfer, and sodium imaging, along with quantitative computed tomography arthrography. These techniques provide promising quantitative imaging biomarkers that can detect early cartilage changes before morphological alterations occur.

Comparison of B0 versus B0 and B1 field inhomogeneity correction for glycosaminoglycan chemical exchange saturation transfer imaging.

PURPOSE: The study compares glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging of intervertebral discs corrected for solely B0 inhomogeneities or both B0 and B1 inhomogeneities. METHODS: Lumbar intervertebral discs of 20 volunteers were examined with T2-weighted and gagCEST imaging. Field inhomogeneity correction was performed with B0 correction only and with correction of both B0 and B1. GagCEST effects measured by the asymmetric magnetization transfer ratio (MTRasym) and signal-to-noise ratio (SNR) were compared between both methods. RESULTS: Significant higher MTRasym and SNR values were obtained in the nucleus pulposus using B0 and B1 correction compared with B0-corrected gagCEST. The GagCEST effect was significantly different in the nucleus pulposus compared with the annulus fibrosus for both methods. CONCLUSION: The B0 and B1 field inhomogeneity correction method leads to an improved quality of gagCEST imaging in IVDs compared with only B0 correction.

Age-related apparent diffusion coefficients of lumbar vertebrae in healthy children at 1.5 T.

BACKGROUND: Diffusion-weighted magnetic resonance imaging with apparent diffusion coefficient (ADC) calculation is important for detecting bone marrow pathologies. OBJECTIVE: To investigate age-related differences of lumbar vertebral body ADC to establish normal values for healthy children. MATERIALS AND METHODS: Forty-nine healthy children without any history of oncological or hematological diseases (10.2±4.7 years, range: 0-20 years) were included in this retrospective study. All magnetic resonance imaging (MRI) examinations were performed at 1.5 T and with similar scan parameters. The diffusion-weighted sequences were performed with b values of 50, 400 and 800 s/mm2. ADC values were measured by placing regions of interest at three different levels within each lumbar vertebral body (L1 to L5). ADC values were analyzed for different age groups (0-2 years, 3-6 years, 7-11 years, 12-14 years, 15-20 years), for each vertebral and intravertebral level. RESULTS: The mean ADC of the whole study group was 0.60±0.09 × 10-3 mm2/s. Children between the ages of 12 and 14 years had significantly higher ADC compared to the other age groups (P≤0.0003). ADC values were significantly higher in the 1st lumbar vertebral body compared to the other levels of the lumbar spine (P<0.005) with the exception of L5, and in the upper third of the vertebral bodies compared to the middle or lower thirds (P≤0.003). CONCLUSION: The age-, vertebral- and intravertebral level-dependent differences in ADC suggest a varying composition and cellularity in different age groups and in different locations.

Institutional computed tomography diagnostic reference levels based on water-equivalent diameter and size-specific dose estimates.

Size-specific institutional diagnostic reference levels (DRLs) were generated for chest and abdominopelvic computed tomography (CT) based on size-specific dose estimates (SSDEs) and depending on patients' water-equivalent diameter (Dw). 1690 CT examinations were included in the IRB-approved retrospective study. SSDEs based on the mean water-equivalent diameter of the entire scan volume were calculated automatically. SSDEs were analyzed for different patient sizes and institutional DRLs (iDRLS; 75% percentiles) based on Dw and SSDEs were generated. iDRLs were compared to the national DRLs. Mean volumetric computed tomography dose index (CTDIvol), Dw and SSDEs for all 1690 CT examinations were 7.2 ± 4.0 mGy (0.84-47.9 mGy), 29.0 ± 3.4 cm and 8.5 ± 3.8 mGy (1.2-37.7 mGy), respectively. Overall, the mean SSDEs of all CT examinations were higher than the CTDIvol in chest CT, abdominopelvic CT and upper abdominal CT, respectively (p < 0.001 for all). There was a strong linear correlation between Dw and SSDEs in chest (R2 = 0.66), abdominopelvic (R2 = 0.98) and upper abdominal CT (R2 = 0.96) allowing for the implementation of size-specific institutional DRLs based on SSDEs and patients' Dw. We generated size-specific, Dw-dependent institutional DRLs based on SSDEs, which allow for easier and more comprehensive analyses of CT radiation exposure. Our results indicate that implementation of SSDEs into national DRLs may be beneficial.

Comparison of glycosaminoglycan chemical exchange saturation transfer using Gaussian-shaped and off-resonant spin-lock radiofrequency pulses in intervertebral disks.

PURPOSE: To investigate, if a train of spin-lock pulses (chemical exchange saturation transfer with spin-lock pulses = CESL) improves biochemical glycosaminoglycan imaging compared with conventional chemical exchange saturation transfer with Gaussian-shaped pulses (CEST) in lumbar intervertebral discs. METHODS: T2 , CEST, and CESL imaging was performed in lumbar intervertebral discs of 15 healthy volunteers at 3 Tesla. Mean and standard deviation of the asymmetric magnetization transfer ratio (MTRasym ), the asymmetric spin-lock ratio (SLRasym ) and T2 values were calculated for nucleus pulposus (NP) and annulus fibrosus (AF). Wilcoxon test was used to analyze differences between MTRasym and SLRasym . Pearson correlation was used to determine the relationship between MTRasym , SLRasym and T2 . RESULTS: Data showed no significant difference between MTRasym and SLRasym (NP: P = 0.35; AF: P = 0.34). MTRasym and SLRasym values differed significantly between NP and AF (MTRasym : P = 0.014, SLRasym : P = 0.005). T2 values correlated significantly with MTRasym (NP: ρ = 0.76, P < 0.001; AF: ρ = 0.60, P < 0.001) and SLRasym (NP: ρ = 0.73, P < 0.001; AF: ρ = 0.47, P < 0.001). CONCLUSION: CESL does not improve the chemical exchange asymmetry effect compared with conventional CEST, but leads to comparable results. Magn Reson Med 78:280-284, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

3D double-echo steady-state sequence assessment of hip joint cartilage and labrum at 3 Tesla: comparative analysis of magnetic resonance imaging and intraoperative data.

OBJECTIVES: To assess the diagnostic accuracy of a high-resolution, three-dimensional (3D) double-echo steady-state (DESS) sequence with radial imaging at 3 Tesla (T) for evaluating cartilage and labral alterations in the hip. METHODS: Magnetic resonance imaging (MRI) data obtained at 3 T, including radially reformatted DESS images and intraoperative data of 45 patients (mean age 42 ± 13.7 years) who underwent hip arthroscopy, were compared. The acetabular cartilage and labrum of the upper hemisphere of the acetabulum and the central femoral head cartilage were evaluated. Sensitivity, specificity, accuracy, and negative and positive predictive values were determined. RESULTS: Sensitivity, specificity and accuracy of the DESS technique were 96.7%, 75% and 93.7% for detecting cartilage lesions and 98%, 76.2% and 95.9% for detecting labral lesions. The positive and negative predictive values for detecting or ruling out cartilage lesions were 96% and 78.9%. For labral lesions, the positive and negative predictive values were 97.5% and 80%. CONCLUSION: A high-resolution, 3D DESS technique with radial imaging at 3 T demonstrated high accuracy for detecting hip cartilage and labral lesions with excellent interobserver agreement and moderate correlation between MRI and intraoperative assessment. KEY POINTS: • High-resolution, 3D DESS with radial imaging allows accurate cartilage and labrum evaluation. • DESS demonstrated high sensitivity, specificity, accuracy for detecting cartilage and labral lesions. • Highly accurate sequence may influence treatment decisions in patients with hip pain.

Metal artifact reduction (MAR) based on two-compartment physical modeling: evaluation in patients with hip implants.

BACKGROUND: Artifacts from metallic implants can hinder image interpretation in computed tomography (CT). Image quality can be improved using metal artifact reduction (MAR) techniques. PURPOSE: To evaluate the impact of a MAR algorithm on image quality of CT examinations in comparison to filtered back projection (FBP) in patients with hip prostheses. MATERIAL AND METHODS: Twenty-two patients with 25 hip prostheses who underwent clinical abdominopelvic CT on a 64-row CT were included in this retrospective study. Axial images were reconstructed with FBP and five increasing MAR levels (M30-34). Objective artifact strength (OAS) (SIart-SInorm) was assessed by region of interest (ROI) measurements in position of the strongest artifact (SIart) and in an osseous structure without artifact (SInorm) (in Hounsfield units [HU]). Two independent readers evaluated subjective image quality regarding metallic hardware, delineation of bone, adjacent muscle, and pelvic organs on a 5-point scale (1, non-diagnostic; 5, excellent image quality). Artifacts in the near field, far field, and newly induced artifacts due to the MAR technique were analyzed. RESULTS: OAS values were: M34: 243.8 ± 155.4 HU; M33: 294.3 ± 197.8 HU; M32: 340.5 ± 210.1 HU; M31: 393.6 ± 225.2 HU; M30: 446.8 ± 224.2 HU and FBP: 528.9 ± 227.7 HU. OAS values were significantly lower for M32-34 compared to FBP (P < 0.01). For overall subjective image quality, results were: FBP, 2.0 ± 0.2; M30, 2.3 ± 0.8; M31, 2.6 ± 0.5; M32, 3.0 ± 0.6; M33, 3.5 ± 0.6; and M34, 3.8 ± 0.4 (P < 0.001 for M30-M34 vs. FBP, respectively). Increasing MAR levels resulted in new artifacts in 17% of reconstructions. CONCLUSION: The investigated MAR algorithm led to a significant reduction of artifacts from metallic hip implants. The highest MAR level provided the least severe artifacts and the best overall image quality.

Silent progression in patients with rheumatoid arthritis: is DAS28 remission an insufficient goal in RA? Results from the German Remission-plus cohort.

BACKGROUND: Remission is arguably the ultimate therapeutic goal in rheumatoid arthritis (RA). Applying modern strategies, clinical remission can be achieved in a substantial number of patients with early RA (ERA). Even in those patients, the number and scope of erosions can increase. We, therefore, investigated the value of MRI for the detection of radiological progression in patients with DAS28 improvement and/or clinical remission of the German Remission-plus cohort. METHODS: Data-sets of 80 RA patients (according to 2010 ACR/EULAR criteria) from the Remission-plus study cohort, who fulfilled the following criteria, were retrospectively analysed: availability of two consecutive MRI scans (low-field MRI, follow-up interval 1 year) of the clinically dominant hand and wrist, and the presence of DAS28 (CRP) scores at both time points, which was used to assess disease activity. RESULTS: Seventy-one of the 80 investigated patients presented a numerical improvement of the DAS28 (CRP) after 12 months (DAS28(CRP) T0 average (Ø) 4.96, SD 1.2; DAS28 T4 (12 month) Ø 2.6, SD 1.0), 73% of them also improved in the RAMRIS-Score, while 24% demonstrated an increase despite DAS28 improvement and 3% showed equal values. 48% of patients who improved in the DAS28 reached EULAR remission. 41% of these patients had an increase in the RAMRIS Erosion-subscore after 12 months. When considering EULAR response criteria (non-response (n = 7), moderate response (n = 19), good response (n = 45)), an increase of erosions was found in 71.4% of non-responders, 52.6% of moderate responders, and 31.1% of good responders after 12 months, all compared to baseline. CONCLUSION: Up to 40% of patients in this study demonstrated a progressive erosive disease detected by MRI despite DAS28 improvement or EULAR remission. Future studies are needed to determine the prognostic clinical impact of disease progression in MRI despite clinical remission, and to investigate if DAS28 remission may be an insufficient therapeutic goal and should be accompanied by MRI remission criteria.