Applicability of 3.0 T MRI images in the estimation of full age based on shoulder joint ossification: Single-centre study

Skeletal maturity is evaluated by many radiological methods for forensic age estimation. Direct radiography and computed tomography lead to a rise in ethical concerns due to radiation exposure. Therefore, magnetic resonance imaging (MRI) has currently been used in recent studies. In this study, the ossification stage of the shoulder joint was determined retrospectively in 178 male and 109 female individuals in the age group 12 to 30 years using 3.0 T MRI. All the images were evaluated with T1-weighted turbo spin echo (T1 TSE) sequence and T1 fast low angle shot two-dimensional sequence (T1 FL2D). The combined staging method, which was defined by Kellinghaus et al. and Schmeling et al., was used. The intra- and inter-observer agreement levels were very good (κ and κ_w). There were no significant age differences between males and females in all stages. In most of the stages, the ossification of the proximal humeral epiphyses occurred earlier in females than in males. Stage 4 did not occur in either of the sexes before the 18th birthday as the youngest patients in this stage was at 19 and 18 years of age in males and females, respectively. We concluded that evaluating the ossification of the proximal humeral epiphysis with MRI imaging for forensic age estimation may be beneficial. Evaluating the same anatomical structure with different MRI sequences may be useful for accurate staging diagnosis.     

Forensic age prediction and age classification for critical age thresholds via 3.0T magnetic resonance imaging of the knee in the Chinese Han population

Objectives

To assess the performance of knee MRI for forensic age prediction and classification for 12-, 14-, 16-, and 18-year thresholds.

Methods

The ossification stages of distal femoral epiphyses and proximal tibial epiphyses were assessed using an integrated staging system by Schmeling et al. and Kellinghaus et al. for knee 3.0T MRI with T1-weighted turbo spin-echo (T1-TSE) in sagittal orientation among 852 Chinese Han individuals (483 males and 369 females) aged 7–30 years. Regression models for age prediction were constructed and their performances were evaluated based on mean absolute deviation (MAD) values. In addition, the performances of age classification were assessed using receiver operating characteristic (ROC) analyses.

Results

The intra- and inter-observer agreement levels were very good (κ > 0.80). The complete fusion of those two types of epiphyses took place before 18.0 years in our study participants. The minimum MAD values were 2.51 years (distal femur) and 2.69 years (proximal tibia) in males, and 2.75 years (distal femur) and 2.87 years (proximal tibia) in females. The specificity values of constructed prediction models were all above 90% for the 12-, 14-, and 16-year thresholds, compared to the 74.8–84.6% for the 18-year threshold. Better performances of age prediction and classification were observed in males by distal femoral epiphyses.

Conclusions

Ossification stages via 3.0T MRI of the knee with T1-TSE sequence using an integrated staging system could be a reliable noninvasive method for age prediction or for age classification for 12-, 14-, and 16-year thresholds, especially in males by distal femoral epiphyses. However, assessments based on the full bony fusion of the distal femoral epiphysis and proximal tibial epiphysis seemed not reliable for age classification for the 18-year threshold in the Chinese Han population.

     

A 2-year follow-up MRI study for the evaluation of an age estimation method based on knee bone development

Age estimation is an actual topic in the area of forensic medicine with a special focus on the age limits of 16 and 18 years. Current research on this topic relies on retrospective data of inhomogeneous populations relating to sex, age range, and socioeconomic status. In this work, we present a 2-year follow-up study for the evaluation of an age estimation method on a prospective magnetic resonance imaging (MRI) knee data collective of a homogeneous population. The study includes 40 male subjects from northern Germany aged 14 to 21 years. Three MRI examinations were evenly acquired within 2 years for each subject. As a first evaluation, a three-stage system was used to assess the ossification status of the knee (I:“open”, II:“partially ossified”, III:“fully ossified”). Three raters assessed the growth plate of the distal femur, proximal tibia, and proximal fibula based on central 2D slices. A good inter-rater agreement was attained (κ = 0.84). All subjects younger than 18 years were rated as stage I and had a cumulative knee score (SKJ) ≤ 5. Based on the follow-up datasets, new parameters quantifying the intra-individual ossification process were calculated. The results of this follow-up analysis show a different start, end, and speed of each growth plate’s maturation as well as an ossification peak for individuals at the age of 16. The generated MRI database provides new insights into the ossification process over time and serves as a basis for further evaluations of age estimation methods.

     

Comparative study of imaging at 3.0 T versus 1.5 T of the knee

Purpose  The objectives of the study were to compare MR imaging at 1.5 and 3.0 T in the same patients concerning image quality and visualization of cartilage pathology and to assess diagnostic performance using arthroscopy as a standard of reference. Materials and methods  Twenty-six patients were identified retrospectively as having comparative 1.5 and 3.0 T MR studies of the knee within an average of 102 days. Standard protocols included T1-weighted and fat-saturated intermediate-weighted fast spin-echo sequences in three planes; sequence parameters had been adjusted to account for differences in relaxation at 3.0 T. Arthroscopy was performed in 19 patients. Four radiologists reviewed each study independently, scored image quality, and analyzed pathological findings. Sensitivities, specificities, and accuracies in diagnosing cartilage lesions were calculated in the 19 patients with arthroscopy, and differences between 1.5 and 3.0 T exams were compared using paired Student’s t tests with a significance threshold of p < 0.05. Results  Each radiologist scored the 3.0 T studies higher than those obtained at 1.5 T in visualizing anatomical structures and abnormalities (p < 0.05). Using arthroscopy as a standard of reference, diagnosis of cartilage abnormalities was improved at 3.0 T with higher sensitivity (75.7% versus 70.6%), accuracy (88.2% versus 86.4%), and correct grading of cartilage lesions (51.3% versus 42.9%). Diagnostic confidence scores were higher at 3.0 than 1.5 T (p < 0.05) and signal-to-noise ratio at 3.0 T was approximately twofold higher than at 1.5 T. Conclusion  MRI at 3.0 T improved visualization of anatomical structures and improved diagnostic confidence compared to 1.5 T. This resulted in significantly better sensitivity and grading of cartilage lesions at the knee.     

Influence of immunologic status on age prediction using signal joint T cell receptor excision circles

Age estimation based on quantifying signal joint T cell receptor excision circle (sjTREC) in T cells has been established to be a promising approach in forensic practice and demonstrated in different ethnic groups. Considering that the homeostasis of T cells carrying sjTRECs is closely related to the immunologic status of a person, it is important to investigate the influence of various immunologic statuses on the age estimation model. In this study, quantification of sjTREC contents was performed for groups of people with various immune system statuses, and the result showed less correlation with chronological age (r ² = 0.424) than in the healthy group (r ² = 0.648). The simulation model indicated that this influence could increase the range of prediction in the age estimation model, and the mean absolute deviation (MAD) between chronological age and predicted age. Through this study, it was demonstrated that immunologic status is a factor that affects the accuracy of age prediction using sjTREC quantification.

     

MRI features of tuberculosis of the knee

Objective  The objective of this study was to describe the magnetic resonance imaging (MRI) features of tuberculosis (TB) of the knee joint. Materials and methods  The MRI features in 15 patients with TB of the knee, as confirmed by histology of the biopsied joint synovium, were reviewed retrospectively. The images were assessed for intra-articular and peri-articular abnormalities. Results  All patients had florid synovial proliferation. The proliferating synovium showed intermediate to low T2 signal intensity. In the patients who were administered intravenous contrast, the hypertrophic synovium was intensely enhancing. Marrow edema (n = 9), osteomyelitis (n = 4), cortical erosions (n = 5), myositis (n = 6), cellulitis (n = 2), abscesses (n = 3), and skin ulceration/sinus formation (n = 2) were seen in the adjacent bone and soft tissue. Conclusion  Synovial proliferation associated with tuberculous arthritis is typically hypointense on T2-weighted images. This appearance, in conjunction with other peri-articular MRI features described, can help in distinguishing TB arthritis from other proliferating synovial arthropathies.     

Forensic age assessment by 3.0T MRI of the knee: proposal of a new MRI classification of ossification stages

Purpose

To explore the possibility of determining majority via a morphology-based examination of the epiphyseal-diaphyseal fusion by 3.0 T magnetic resonance imaging (MRI), a prospective cross-sectional study developing and applying a new stage classification was conducted.

Materials and methods

344 male and 350 female volunteers of German nationality between the ages of 12-24 years were scanned between May 2013 and June 2015. A 3.0 T MRI scanner was used, acquiring a T1-weighted (T1-w) turbo spin-echo sequence (TSE) and a T2-weighted (T2-w) TSE sequence with fat suppression by spectral pre-saturation with inversion recovery (SPIR). The gathered information was sifted and a five-stage classification was formulated as a hypothesis. The images were then assessed using this classification. The relevant statistics were defined, the intra- and interobserver agreements were determined, and the differences between the sexes were analysed.

Results

The application of the new classification made it possible to correctly assess majority in both sexes by the examination of the epiphyses of the knee joint. The intra- and interobserver agreement levels were very good (κ > 0.80). The Mann-Whitney-U Test implied significant sex-related differences for most stages.

Conclusion

Applying the presented MRI classification, it is possible to determine the completion of the 18th year of life in either sex by 3.0 T MRI of the knee joint.

Key points

? Based on prospective referential data a new MRI classification was formulated. ? The setting allows assessment of the age of an individual’s skeletal development. ? The classification scheme allows the reliable determination of majority in both sexes. ? The staging shows a high reproducibility for instructed and trained professional personnel. ? The proposed classification is likely to be adaptable to other long bone epiphyses.

     

MRI of the popliteofibular ligament: isotropic 3D WE-DESS versus coronal oblique fat-suppressed T2W MRI

Objective The objective was to compare isotropic 3D water excitation double-echo steady state (WE-DESS) MRI with coronal oblique fat-suppressed T2-weighted (FS T2W) images in the identification of the popliteofibular ligament (PFL). Materials and methods A prospective analysis of 122 consecutive knee MRIs was performed in patients referred for knee pain from the orthopaedic clinic. In addition to the standard knee sequences, isotropic WE-DESS volume acquisition through the whole knee and coronal oblique FS T2W fast spin echo sequences through the posterolateral corner were obtained. The presence of the popliteus and biceps femoris tendons, lateral collateral and PFL was documented. Anterior cruciate ligament injury was present in 33 cases and these were excluded from the study because of the risk of associated PFL injury, leaving a total of 89 cases. Of the 42 patients in whom arthroscopic evaluation was subsequently obtained, none were found to have an injury to the PFL. Results The lateral collateral ligament, biceps femoris and popliteus tendon were identified in all cases on all sequences. The PFL was seen in 81 (91.0%; 95% CI 85.1–97.0%) patients using the WE-DESS sequence and 63 (70.8%; 95% CI 61.3–80.2%) patients using the coronal oblique FS T2W sequence, a statistically significant difference (p < 0.00005). Conclusion Isotropic 3D WE-DESS MRI significantly enhances our ability to identify the popliteofibular ligament compared with coronal oblique fat-suppressed T2-weighted images.     

Comparison of T2-weighted spin-echo and fast spin-echo techniques in the evaluation of myelination

To evaluate T2-weighted fast spin-echo (FSE) and conventional spin-echo (CSE) magnetic resonance (MR) techniques in the assessment of brain myelination, 100 consecutive pediatric patients were imaged prospectively with both CSE and FSE sequences. All patients underwent a routine MR examination that included T2-weighted CSE imaging (imaging time, 10 minutes 21 seconds) and T2-weighted FSE imaging (imaging time, 2 minutes 5 seconds). The two techniques were compared for estimating the degree of myelination (using normal anatomic landmarks) by blind review. With T2-weighted CSE images as the “gold standard” for estimation of normal myelination, FSE images were evaluated to determine if they showed the degree of myelination similarly to CSE images. There was a strong correlation (P <.01) between CSE and FSE images in the estimation of myelination over a wide range of patient ages.     

Evaluation of grades 3 and 4 chondromalacia of the knee using T2*-weighted 3D gradient-echo articular cartilage imaging

Objective. To determine the accuracy of T2*-weighted three-dimensional (3D) gradient-echo articular cartilage imaging in the identification of grades 3 and 4 chondromalacia of the knee. Design and patients. A retrospective evaluation of 80 patients who underwent both arthroscopic and MRI evaluation was performed. The 3D images were interpreted by one observer without knowledge of the surgical results. The medial and lateral femoral condyles, the medial and lateral tibial plateau, the patellar cartilage and trochlear groove were evaluated. MR cartilage images were considered positive if focal reduction of cartilage thickness was present (grade 3 chondromalacia) or if complete loss of cartilage was present (grade 4 chondromalacia). Comparison of the 3D MR results with the arthroscopic findings was performed. Results. Eighty patients were included in the study group. A total of 480 articular cartilage sites were evaluated with MRI and arthroscopy. Results of MR identification of grades 3 and 4 chondromalacia, all sites combined, were: sensitivity 83%, specificity 97%, false negative rate 17%, false positive rate 3%, positive predictive value 87%, negative predictive value 95%, overall accuracy 93%. Conclusion. The results demonstrate that T2*-weighted 3D gradient-echo articular cartilage imaging can identify grades 3 and 4 chondromalacia of the knee. Received: 18 April 2000 Revision requested: 18 July 2000 Revision received: 10 October 2000 Accepted: 27 November 2000     

USPIO-enhanced magnetic resonance imaging of the knee in asymptomatic volunteers

The aim of this study was to compare signal characteristics of the synovium in knees of asymptomatic volunteers before and after intravenous administration of ultrasmall superparamagnetic iron oxide particles (USPIO). Ten knees of 10 asymptomatic volunteers were examined before and 36 h after intravenous administration of USPIO on a 1.5-T MR system using T1-weighted spin-echo, T2-weighted fast spin-echo, T2*-weighted gradient-echo (GRE), and short inversion time inversion-recovery sequences. In addition, synovial perfusion was measured using Gd-enhanced GRE imaging during the first imaging session. Images were analyzed qualitatively for any visual changes before and after USPIO administration. Signal-to-noise ratios (SNR) of the synovium were determined on unenhanced and USPIO-enhanced sequences. All MR images were reviewed for presence of any degenerative changes. Qualitative image analysis revealed no visually detectable changes of any knee joint before and after USPIO administration. The SNR values of the synovium on T1w, T2w, and T2*w images before and after USPIO administration showed no significant difference (T1, P = 0.86; T2, P = 0.95; T2*, P = 0.86). None of the volunteers showed any relevant degenerative changes of the knee and synovial perfusion was within normal limits. In knees of asymptomatic volunteers without any relevant degenerative changes and normal synovial perfusion neither visual changes nor changes of SNR values of the synovium can be depicted after USPIO administration. This means that USPIO-enhanced MRI may be used for assessment of knee disorders with increased macrophage activity.     

Evaluation of the radiographic visibility of the root pulp in the lower third molars for the purpose of forensic age estimation in living individuals

The question of whether an individual has reached the age of 18 is of crucial importance in forensic age estimation practice. In some countries, the age threshold of 21 years is relevant as well. A completed mineralization of third molars is not a sufficient criterion for a diagnosis of a minimum age of 18 years with the required probability. In a material of 1,198 orthopantomograms from 629 females and 569 males aged between 15 and 40 years, the visibility of the root pulp of fully mineralized lower third molars was evaluated according to stages 0, 1, 2, and 3. In females, stage 0 was first noticed at age 17.2 years, in males at age 17.6 years. In either sex, the earliest observation of stage 1 was between 21.0 and 22.4 years. Stage 2 was first achieved by males between 22.3 and 22.7 years, by females between 23.4 and 24.7 years. The occurrence of stage 3 was first found in both sexes between 25.1 and 25.9 years. These findings indicate that for stage 0, an age below 18 years cannot be excluded. However, for stage 1, the examined individual must be over 18 years of age and most probably over 21 years of age. For stages 2 and 3, the age can safely be stated to be over 21 years of age. This method may be a powerful tool for forensic dentists in age estimation in asylum and criminal proceedings.     

Comparison of image quality in magnetic resonance imaging of the knee at 1.5 and 3.0 Tesla using 32-channel receiver coils

We examined to what degree the visualization of anatomic structures in the human knee is improved using 3.0-T magnetic resonance imaging (MRI) and many element RF receive coils as compared to 1.5 T. We imaged 20 knees at 1.5 and 3.0 T using T2-weighted STIR, T2-weighted gradient echo, T1-weighted spin-echo, true-FISP and T2-weighted fast spin echo techniques in conjunction with 32-element RF coil arrays. The 3.0-T examination was considerably faster than its 1.5-T counterpart. A superior subjective visibility at 3.0 T vs 1.5 T was found in 27 of 50 evaluated structures (meniscus, ligaments) with the exception of true-FISP techniques. The 3.0-T examination provided a better visibility (evaluated by blinded consensus-reading by two radiologists) of small structures such as the ligamentum transversum genu. Also, cartilage was better delineated at 3.0 T. A 23% increased average signal-to-noise ratio as assessed using a temporal filter was observed at 3.0 T as compared to 1.5 T. At 3.0 T, imaging of the human knee is faster and results in a subjective visibility of anatomic structures that is superior to and competitive with 1.5 T.     

Magnetic resonance imaging signs of iliotibial band friction in patients with isolated medial compartment osteoarthritis of the knee

Background  The purpose of this retrospective study was to assess the frequency of magnetic resonance imaging (MRI) signs of iliotibial band friction (ITBF) in patients with advanced medial compartment knee osteoarthritis. Material and methods  Proton density-weighted (PDw) fat-saturated (fatsat) MR images (1.5 T, slice thickness (SL) 2.5–3 mm, eight-channel phased array coil) of 128 patients with isolated advanced osteoarthritis of the medial knee compartment and complete or subtotal (>80%) loss of cartilage were evaluated. There were 41 men and 87 women. Mean age was 63 years, range 34–89 years. The control group consisted of 94 patients with medial meniscus degeneration without cartilage loss (56 men and 38 women, mean age 50 years, range 16–89 years). MRI signs of ITBF were evaluated in both groups [poorly defined abnormalities of signal intensity and localized fluid collection lateral, distal or proximal to the lateral epicondyle; signal intensity abnormalities superficial to or deep by the iliotibial band (ITB)]. Transverse images were evaluated separately. Consensus evaluation using all imaging planes was performed. Results  Of 128 patients with osteoarthritis, 95 had moderate or advanced MRI signs of ITBF (74.2%). Eighty-nine patients (69.5%) had advanced degeneration of the meniscus. In the control group, 26 of 94 patients had only moderate MRI signs of ITBF. There was a statistically significant difference between both groups for the presence of MR signs of ITBF (P ≤ 0.01). Conclusion  MRI signs of ITBF were frequently present in patients with severe medial compartment osteoarthritis of the knee. Joint space narrowing with varus knee deformity may be a cause of ITBF. Level of evidence  Level 4 (Historic, non-randomized, retrospective, cohort study with a control group)     

Dedifferentiated chondrosarcoma of the appendicular skeleton: MRI-pathological correlation

Objective To correlate the T2-weighted and STIR MRI appearances of dedifferentiated appendicular chondrosarcoma with gross and microscopic pathology.Design and patients Nine patients with a histologically confirmed diagnosis of dedifferentiated appendicular chondrosarcoma were identified from the Bone Tumour Registry. All patients underwent MRI, including T2-weighted and/or STIR sequences in at least one plane, prior to limb salvage surgery. Areas of reduced signal intensity (SI) compared with hyperintense chondral tumour on the T2-weighted or STIR images were correlated with the resection specimen, to determine the relationship of such out areas of reduced SI with regions of dedifferentiation.Results and conclusions Patients presented over a period of 7 years. There were five men and four women with mean age 68.2 years and age range 51–78 years. Tumours arose in the femur (6 cases), humerus (2 cases) and tibia (1 case). Three MRI patterns were identified: (1) type 1, a lesion with two distinct signal characteristics—hyperintense chondral and reduced SI dedifferentiated tumour (n=6); type 2, mainly reduced SI lesion—dedifferentiated tumour, with areas of signal void corresponding to matrix calcification (n=2); type 3, a heterogeneous lesion with no radiological evidence of underlying chondral tumour (n=1). T2-weighted or STIR MR sequences can identify areas of dedifferentiation, which should be the preferential site of pre-operative biopsy.     

Off-site evaluation of liver lesion detection by Gd-BOPTA-enhanced MR imaging

The aim of this study was to determine the efficacy of Gd-BOPTA-enhanced MRI in liver lesion detection in comparison with unenhanced MRI and dynamic CT. The image sets of 148 of 151 patients enrolled in a multicenter German phase-III trial were evaluated by two independent radiologists unaffiliated with the investigating centers. Patients underwent a routine MRI protocol comprising T2- and T1-weighted spin-echo and T1-weighted gradient-echo (GE) sequences pre and 1 h post 0.1 mmol/kg Gd-BOPTA (Bracco-Byk Gulden, Konstanz, Germany). Additionally, a serial T1-weighted GE scan was performed after administration of the first half of the dose. All patients underwent dynamic contrast-enhanced CT. The evaluation was performed with regard to the number and size of lesions detected per patient by each modality or sequence. Furthermore, all pre CM and pre + post CM image sets were analyzed for number of lesions per patient. Both readers detected significantly more lesions in the contrast-enhanced image set compared with the unenhanced image set (32 and 39 %, respectively; p < 0.0001). While contrast-enhanced CT detected a similar number of lesions to unenhanced MRI, it was clearly inferior to contrast-enhanced MRI (reader 1: p = 0.0117; reader 2: p = 0.0225). Of the T1-weighted scans performed, the dynamic and late T1-weighted GE exams contributed most to the increased lesion detection rate (reader 1: p = 0.0007; reader 2: p = 0.0037). The size of the smallest lesion detected by means of MRI was significantly larger in the pre-CM image sets than in the pre + post CM image sets (reader 1: p = 0.001; reader 2: p < 0.0001). Gd-BOPTA-enhanced MRI detected significantly smaller lesions than contrast-enhanced CT (reader 1: p = 0.0117; reader 2: p = 0.0925). Gd-BOPTA-enhanced MR imaging improves liver lesion detection significantly over unenhanced MRI and dynamic CT. Received: 18 October 1999/Revised: 19 June 2000/Accepted: 21 June 2000     

MR imaging of the brainstem: normal postnatal development

Summary Magnetic resonance imaging (MRI) of the mesencephalon during the first four years of life allowed normal maturational processes of the various midbrain structuresin vivo to be followed. Using T2-weighted SE sequences, we found 5 characteristic age dependent patterns on axial tomograms taken at the level of the superior colliculi, that let us derive a grading system for normal development of the quadrigeminal plate, the cerebral peduncles, the reticular substantia nigra and the red nuclei. A subsequent statistical analysis of these age dependent changing patterns on T2-weighted MRI of 60 neonates, infants and small children yielded normal age ranges for each of the 5 maturational stages of the midbrain. Grading the changing pattern of midbrain structures during early postnatal life into 5 distinct maturational stages allowed not only monitoring of normal differentiation, e.g. myelination of the brainstemin vivo, but may also help to distinguish between normal, delayed and abnormal development of the mesencephalon on routine MRI.     

Magnetic resonance imaging of intracranial atherosclerosis: Comparison of ex vivo 3T MRI and histologic findings

PurposeImaging the lipid-rich necrotic core (LRNC) is very important when evaluating the response of lipid-lowering therapy. The purpose of this study was to assess ex vivo LRNC of intracranial atherosclerosis using 3T MRI.Materials and methodsThirty-one atherosclerotic lesions from 17 specimens were analyzed (basilar artery = 15, middle cerebral artery = 16) using 3T MRI. Specimens were not chemically processed for imaging studies. Reconstructed MRI was matched with histologic sections at corresponding locations.ResultsThe median plaque thickness of intracranial atherosclerosis was 0.6 mm (0.4–2.0 mm). All specimens had a LRNC on histologic findings. Three specimens had plaque calcification on histologic findings. LRNC of 30 specimens (96.8%) appeared as homogeneous isointensity/hypointensity on T1-weighted imaging and hypointensity on T2-weighted imaging compared with T1-weighted imaging.ConclusionsAll specimens with ex vivo intracranial atherosclerosis had LRNC. Intracranial atherosclerosis could be an indication for lipid-lowering therapy, similar to previous carotid MR studies.     

Signal intensity of motor and sensory cortices on T2-weighted and FLAIR images: intraindividual comparison of 1.5T and 3T MRI

We compared the signal intensity of motor and sensory cortices on T2-weighted and FLAIR images obtained at 3T and 1.5T. MR images of 101 consecutive neurologically normal patients who underwent both 1.5T and 3T MRI were retrospectively evaluated. The signal intensities of motor and sensory cortices were analyzed both visually and quantitatively in comparison with superior frontal cortex. On T2-weighted images, decreased signal intensity of the motor cortex was seen in 6 (32%) of 19 patients aged 61–70 years and 14 (48%) of 29 at 71 years and older at 3T, compared with only 1 (5%) and 2 (7%) at 1.5T, respectively. On FLAIR images, the decreased signal intensity in the motor cortex was also more frequently seen at 3T than at 1.5T. The mean CNRs of motor and sensory cortices were significantly higher at 3T than at 1.5T on both T2-weighted and FLAIR images. The decreased signal intensity in the motor cortex was frequently seen at 3T compared with 1.5T. Knowledge of the finding at 3T can help the recognition of abnormalities of the motor cortex caused by various pathologic conditions.     

Assessment of cartilage-dedicated sequences at ultra-high-field MRI: comparison of imaging performance and diagnostic confidence between 3.0 and 7.0 T with respect to osteoarthritis-induced changes at the knee joint

Objective  The objectives of the study were to optimize three cartilage-dedicated sequences for in vivo knee imaging at 7.0 T ultra-high-field (UHF) magnetic resonance imaging (MRI) and to compare imaging performance and diagnostic confidence concerning osteoarthritis (OA)-induced changes at 7.0 and 3.0 T MRI. Materials and methods  Optimized MRI sequences for cartilage imaging at 3.0 T were tailored for 7.0 T: an intermediate-weighted fast spin-echo (IM-w FSE), a fast imaging employing steady-state acquisition (FIESTA) and a T1-weighted 3D high-spatial-resolution volumetric fat-suppressed spoiled gradient-echo (SPGR) sequence. Three healthy subjects and seven patients with mild OA were examined. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), diagnostic confidence in assessing cartilage abnormalities, and image quality were determined. Abnormalities were assessed with the whole organ magnetic resonance imaging score (WORMS). Focal cartilage lesions and bone marrow edema pattern (BMEP) were also quantified. Results  At 7.0 T, SNR was increased (p < 0.05) for all sequences. For the IM-w FSE sequence, limitations with the specific absorption rate (SAR) required modifications of the scan parameters yielding an incomplete coverage of the knee joint, extensive artifacts, and a less effective fat saturation. CNR and image quality were increased (p < 0.05) for SPGR and FIESTA and decreased for IM-w FSE. Diagnostic confidence for cartilage lesions was highest (p < 0.05) for FIESTA at 7.0 T. Evaluation of BMEP was decreased (p < 0.05) at 7.0 T due to limited performance of IM-w FSE. Conclusion  Gradient echo-based pulse sequences like SPGR and FIESTA are well suited for imaging at UHF which may improve early detection of cartilage lesions. However, UHF IM-w FSE sequences are less feasible for clinical use.