Relationship between diameter asymmetry and blood flow in the pre-communicating (A1) segment of the anterior cerebral arteries.

BACKGROUND: Asymmetry in diameter between pre-communicating (A1) segments of the anterior cerebral arteries is related to anterior communicating artery aneurysm formation. Diameter asymmetry definitions vary and have not been related to blood flow measurements using the same imaging modality. We aimed to evaluate the relationship between A1-diameter asymmetry and blood flow asymmetry and to define a hemodynamically significant cut-off value for A1-diameter asymmetry. We assessed sex differences between different groups of A1-asymmetry. MATERIALS AND METHODS: 3-Tesla time-of-flight MRA and 4D-phase-contrast MRI were performed in 122 healthy participants. Diameter and blood flow measurements were performed halfway in both A1-segments. Participants were subdivided based on A1-diameter asymmetry: ≤10% (symmetric); 11-20%; 21-30%; 31-40%; and >40% (increasing asymmetry) groups. We studied the relationship between A1-diameter asymmetry and corresponding flow asymmetry (scatterplot and correlation). A hemodynamic-based cutoff value for A1-asymmetry was determined by comparing dominant A1 blood flow in the asymmetry groups to the mean blood flow of the symmetric A1-group (linear mixed-effects model). Sex-related differences in A1-diameter, blood flow and asymmetry were assessed with t-tests. RESULTS: A1-diameter asymmetry was linearly related to blood flow asymmetry between dominant and non-dominant sides. A1-diameter asymmetry >30% yielded statistically significant increased blood flow in the dominant A1 compared to symmetric A1s. Men had statistically significant larger A1-diameters, higher blood flow and a similar degree of A1-diameter asymmetry compared to women. CONCLUSION: A1-diameter asymmetry is linearly related to blood flow asymmetry. A >30% A1-asymmetry can be used as hemodynamically significant cut-off value. There were no sex-related differences in A1-diameter asymmetry.

Can Non-Contrast 3T MRI scans predict the type of labral procedure in hip arthroscopy?

PURPOSE: The study proposed a simple classification system that aimed at predicting the labral procedure during hip arthroscopy using images from unenhanced 3T MRI scans. PATENTS AND METHODS: Forty patients undergoing hip arthroscopy had their MRI scans reviewed pre-operatively by one of two senior radiologists and classified into: type 1: stable labrum with intra-substance degeneration (no labral repair required), type 2: unstable labrum, no intra-substance degeneration (labral repair required), or type 3: unstable labrum with intra-substance degeneration (Labral repair not feasible). Hip arthroscopy is carried out by one of two surgeons and classified accordingly while blinded to the radiologists' assessment. RESULTS: The pre-operative radiological classification managed to predict the labral procedure in 29 cases out of 40 (72.5%). The gamma value was 0.83, and the kappa value was 0.46 denoting moderate agreement. The inter-class correlation coefficient was 0.52 indicating moderate reliability. CONCLUSION: The proposed classification showed a moderate agreement between the radiological findings and arthroscopic findings. As we cannot accurately correlate the MRI findings with the type of surgical management, the surgeon should be prepared for all scenarios of labral procedures. LEVEL OF EVIDENCE: Level IV (case series).

Deep neural network based CEST and AREX processing: Application in imaging a model of Alzheimer's disease at 3 T.

PURPOSE: To optimize and apply deep neural network based CEST (deepCEST) and apparent exchange dependent-relaxation (deepAREX) for imaging the mouse brain with Alzheimer's disease (AD) at 3T MRI. METHODS: CEST and T1 data of central and anterior brain slices of 10 AD mice and 10 age-matched wild type (WT) mice were acquired at a 3T animal MRI scanner. The networks of deepCEST/deepAREX were optimized and trained on the WT data. The CEST/AREX contrasts of AD and WT mice predicted by the networks were analyzed and further validated by immunohistochemistry. RESULTS: After optimization and training on CEST data of WT mice, deepCEST/deepAREX could rapidly (~1 s) generate precise CEST and AREX results for unseen CEST data of AD mice, indicating the accuracy and generalization of the networks. Significant lower amide weighted (3.5 ppm) signal related to amyloid ß-peptide (Aß) plaque depositions, which was validated by immunohistochemistry results, was detected in both central and anterior brain slices of AD mice compared to WT mice. Decreased magnetization transfer (MT) signal was also found in AD mice especially in the anterior slice. CONCLUSION: DeepCEST/deepAREX could rapidly generate accurate CEST/AREX contrasts in animal study. The well-optimized deepCEST/deepAREX have potential for AD differentiation at 3T MRI.

Fatty Acid Composition of Proximal Femur Bone Marrow Adipose Tissue in Subjects With Systemic Lupus Erythematous Using 3 T Magnetic Resonance Spectroscopy.

BACKGROUND: Systemic lupus erythematosus (SLE) is a chronic, inflammatory disease with common musculoskeletal manifestations, notably reductions in bone quality. Bone marrow adipose tissue composition and quantity has been previously linked to bone quality and may play a role in SLE pathophysiology but has not been thoroughly studied. PURPOSE: To use magnetic resonance spectroscopy (MRS) to investigate bone marrow adipose tissue quantity and composition in proximal femur subregions of untreated SLE patients compared to controls and treated patients. STUDY TYPE: Prospective. SUBJECTS: A total of 64 female subjects: 28 SLE, 15 glucocorticoid (GC)-treated SLE and 21 matched controls. FIELD STRENGTH/SEQUENCE: Stimulated echo acquisition mode (STEAM) sequence at 3 T. ASSESSMENT: MRS was performed at multiple echo times in the femoral neck and trochanter regions and fatty acids (FA) composition was computed. STATISTICAL TESTS: Intergroup comparisons were carried out using ANOVA. A P value < 0.05 was considered statistically significant. RESULTS: SLE patients had significantly higher saturated FA compared to controls in both the femoral neck (+0.12) and trochanter (+0.11), significantly lower monounsaturated FA in the trochanter compared to controls (-0.05), and significantly lower polyunsaturated FA in the femoral neck compared to both controls (-0.07) and SLE patients on GC therapy (-0.05). DATA CONCLUSION: SLE patients have altered proximal femur marrow fat metabolism, which may reflect a manifestation of, or play a role in, the altered inflammatory response of these patients. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Anatomy of the distal biceps tendon: an in vivo 3-T magnetic resonance imaging study.

BACKGROUND: On the basis of the current literature, the optimal surgical technique for distal biceps tendon tears remains controversial. Cadaveric studies have investigated distal biceps anatomy but are limited by cohort size and tissue factors. We sought to investigate distal biceps anatomy in vivo by retrospectively reviewing magnetic resonance imaging (MRI) scans. An improved understanding of the anatomy of the distal biceps tendon will lead to better definition of the optimal anatomic surgical repair. METHODS: Two independent observers retrospectively reviewed 3-T MRI scans of elbows. Basic demographic data were collected, and measurements of tendon length, footprint width, footprint length, and footprint angle were taken using simultaneous tracker lines and a standardized technique. From the biceps muscle belly distally, the presence of a single tendon or double tendons was recorded and the tendon interdigitation point was measured if relevant. RESULTS: A total of 106 3-T MRI scans of 106 elbows of 103 patients were included. There were 71 male and 32 female patients, and the mean age was 44.7 years. Most distal biceps tendons exited the biceps muscle belly as separate entities (91%, 96 of 106 elbows) and then coalesced prior to insertion on the radial tuberosity (91%, 87 of 96 elbows). There was a positive correlation between tendon length and footprint length (P < .05), as well as between tendon length and footprint width (P < .05). The mean tendon length was 65.2 mm (95% confidence interval [CI], 63.3-66.8 mm; range, 44.3-86.8 mm), the mean distance from the musculotendinous junction to the interdigitation point was 38.3 mm (95% CI, 35.8-40.9 mm; range, 8.9-64.8 mm), the mean footprint width was 10.3 mm (95% CI, 9.9-10.7 mm; range, 5.9-16.3 mm), the mean footprint length was 16.2 mm (95% CI, 15.6-16.9; range, 7.3-25.4 mm), and the mean footprint angle was 32.1° (95% CI, 29.5°-34.6°; range, 8.5°-84.3°). CONCLUSION: An in vivo, high-resolution study of the anatomy of the distal biceps tendon improves our understanding of its complex morphology and hence our ability to perform an anatomic "footprint repair."

Anatomic factors associated with partial distal biceps tendon tears: a comparative control study.

BACKGROUND: There is minimal literature on the anatomic factors associated with partial distal biceps tendon (DBT) tears. It has been proposed that a larger radial tuberosity size-and, therefore, a smaller radioulnar space during pronation-may cause mechanical impingement of the DBT predisposing to tears. We sought to investigate the anatomic factors that may be associated with partial DBT tears by retrospectively reviewing the DBT anatomy using 3-T magnetic resonance imaging (MRI) scans of elbows with partial DBT tears and a comparison group of normal elbows. METHODS: Two independent observers retrospectively reviewed 3-T MRI scans of elbows with partial DBT tears and elbows without visible pathology. Basic demographic data were collected, and measurements of radial tuberosity length, radial tuberosity thickness, radioulnar space, and radial tuberosity-ulnar space were made using simultaneous tracker lines and a standardized technique. The ratio of radial tuberosity thickness to radial diameter and the ratio of radioulnar space to radial tuberosity-ulnar space were calculated. The presence or absence of enthesophytes and the presence of a single DBT vs. double DBTs were noted. RESULTS: This study included twenty-six 3-T MRI scans of 26 elbows with partial DBT tears and thirty 3-T MRI scans of 30 elbows without pathology. Basic demographic data were comparable between the 2 groups. The tear group showed statistically significantly larger mean measurements for radial tuberosity length (24.3 mm vs. 21.3 mm, P = .002) and radial tuberosity thickness (5.5 mm vs. 3.7 mm, P < .0001). The tear group also showed statistically significantly smaller measurements for radioulnar space (8.2 mm vs. 10.0 mm, P = .010) and radial tuberosity-ulnar space (7.2 mm vs. 9.1 mm, P = .013). The ratio of radial tuberosity thickness to radial diameter was statistically significantly larger in the tear group (0.389 vs. 0.267, P < .0001). There was a statistically significant positive correlation between partial DBT tears and the presence of enthesophytes (P = .007), as well as between partial DBT tears and the presence of 2 discrete DBTs rather than a single tendon or 2 DBTs that interdigitated prior to insertion (P < .0001). CONCLUSION: Larger radial tuberosities and smaller radioulnar and radial tuberosity-ulnar spaces are associated with partial DBT tears. Larger tuberosities and a smaller functional space for the DBT may lead to chronic impingement, tendon delamination, and consequent weakness, which ultimately lead to tears. Enthesophytes may be associated with tears for the same reason. The presence of 2 discrete DBTs that do not interdigitate prior to insertion is also associated with partial tears. This study will help clinicians understand the pathogenesis of partial DBT tears.

Comparison of intraoperative and post-operative 3-T MRI performed at 24-72 h following brain tumour resection in children.

PURPOSE: Intraoperative MRI (ioMRI) is a valuable tool aiding paediatric brain tumour resection. There is no published evidence comparing the effectiveness of the final intraoperative MRI and early post-operative (24-72 h) MRI as baseline scans following brain tumour resection. We aimed to evaluate whether the final ioMRI scan could serve as the post-operative baseline scan after paediatric brain tumour resections. METHODS: This prospective study compared the final ioMRI scan with the immediate post-operative MRI scan performed 24-72 h post-surgery. We included 20 patients aged 6.6-21 years undergoing brain tumour resection using ioMRI and were suitable for MRI scan without general anaesthesia. The scans were independently evaluated by experienced local and external paediatric neuroradiologists. Identical sequences in the final ioMRI and the 24-72-h MRI were compared to assess the extent of resection, imaging characteristics of residual tumour, the surgical field, extent of surgically induced contrast enhancement, and diffusion abnormalities. RESULTS: In 20 patients undergoing intraoperative and early post-operative MRI, there was no difference between ioMRI and 24-72-h post-op scans in identifying residual tumour. Surgically induced contrast enhancement was similar in both groups. There were more abnormalities on diffusion imaging and a greater degree of oedema around the surgical cavity on the 24-72-h scan. CONCLUSION: The final 3-T ioMRI scan may be used as a baseline post-operative scan provided standard imaging guidelines are followed and is evaluated jointly by the operating neurosurgeon and neuroradiologist. Advantages of final ioMRI as a baseline scan are identified.

Translating pH-sensitive PROgressive saturation for QUantifying Exchange rates using Saturation Times (PRO-QUEST) MRI to a 3T clinical scanner.

PURPOSE: To translate the recently developed PRO-QUEST (Progressive saturation for quantifying exchange rates using saturation times) sequence from preclinical 9.4T to 3T clinical magnetic field strength. METHODS: Numerical simulations were performed to define the optimal saturation flip angles for PRO-QUEST saturation pulses at 3T and demonstrate the effect of a ∆T2 error on the exchange rate (kex ) estimation at various field strengths. Exchange-dependent relaxation rate (Rex ) was measured for glutamate solutions in various pH, healthy volunteers and patients with multiple sclerosis (MS). Additionally, concentration-independent ratiometric Rex maps were produced to evaluate regional signal variations across the brain of human volunteers. RESULTS: The calculated Rex significantly correlates with pH in glutamate samples, however, kex values are underestimated as compared to those previously obtained at 9.4T. In the ratiometric Rex map of healthy volunteers, no significant differences are found between grey matter, white matter, and basal ganglia. In patients with MS, white matter lesions are visible in single saturation power Rex maps whereas only a periventricular lesion is apparent in the ratiometric Rex map. CONCLUSION: We demonstrate that quantification of pH sensitive indices using PRO-QUEST is feasible at 3T within clinically acceptable acquisition times. Our initial findings in patients with MS show that pH sensitive indices varied with the type of lesion examined whereas no significant difference was found in healthy volunteers between tissue types, suggesting that it would be worthwhile to apply PRO-QUEST in a larger cohort of patients to better understand its distinct imaging features relative to conventional techniques.

Natively fat-suppressed 5D whole-heart MRI with a radial free-running fast-interrupted steady-state (FISS) sequence at 1.5T and 3T.

PURPOSE: To implement, optimize, and test fast interrupted steady-state (FISS) for natively fat-suppressed free-running 5D whole-heart MRI at 1.5 tesla (T) and 3T. METHODS: FISS was implemented for fully self-gated free-running cardiac- and respiratory-motion-resolved radial imaging of the heart at 1.5T and 3T. Numerical simulations and phantom scans were performed to compare fat suppression characteristics and to determine parameter ranges (number of readouts [NR] per FISS module and TR) for effective fat suppression. Subsequently, free-running FISS data were collected in 10 healthy volunteers and images were reconstructed with compressed sensing. All acquisitions were compared with a continuous balanced steady-state free precession version of the same sequence, and both fat suppression and scan times were analyzed. RESULTS: Simulations demonstrate a variable width and location of suppression bands in FISS that were dependent on TR and NR. For a fat suppression bandwidth of 100 Hz and NR ≤ 8, simulations demonstrated that a TR between 2.2 ms and 3.0 ms is required at 1.5T, whereas a range of 3.0 ms to 3.5 ms applies at 3T. Fat signal increases with NR. These findings were corroborated in phantom experiments. In volunteers, fat SNR was significantly decreased using FISS compared with balanced steady-state free precession (P < 0.05) at both field strengths. After protocol optimization, high-resolution (1.1 mm3 ) 5D whole-heart free-running FISS can be performed with effective fat suppression in under 8 min at 1.5T and 3T at a modest scan time increase compared to balanced steady-state free precession. CONCLUSION: An optimal FISS parameter range was determined enabling natively fat-suppressed 5D whole-heart free-running MRI with a single continuous scan at 1.5T and 3T, demonstrating potential for cardiac imaging and noncontrast angiography.

A comparative evaluation of the Eustachian tube cartilage between healthy and diseased ears using a 3 Tesla MRI.

PURPOSE: The purpose of this study was to prospectively assess the Eustachian tube (ET) cartilage using 3 Tesla (3T) magnetic resonance imaging (MRI) and compare the results between healthy ears and those with a middle ear disease. MATERIAL AND METHODS: The study included 56 ears with a middle ear disease as the patient group and 100 ears without a middle ear disease as the control group. The patients' age ranged from 18 to 65 years. The axial three-dimensional (3D) multiple echo recombined gradient echo (MERGE) sequence and oblique parasagittal planes were obtained. Visualisation of the ET cartilage was assessed on the MR images using a three-point numerical rating score. In the axial plane, the ET lumen's diameter was measured from the mid-portion of the cartilage. RESULTS: There was no significant difference between the patient group and the control group according to patients' age and gender, and the medial laminal thickness of the ET cartilage. In the patient group, the diameter of the ET cartilage was significantly smaller than in the control group. The ET lumen diameter was significantly lower according to each of the three scoring systems. CONCLUSIONS: 3T MRI provides an evaluation of the ET cartilage and isthmus level, which are small but important anatomical localisations and surgical landmarks. MR imaging has the potential to provide essential information on ET prior to new surgical treatments, such as balloon dilation for middle ear diseases.

Accelerated 3D T2 mapping with dictionary-based matching for prostate imaging.

PURPOSE: To develop a fast and accurate method for 3D T2 mapping of prostate cancer using undersampled acquisition and dictionary-based fitting. METHODS: 3D high-resolution T2 -weighted images (0.9 × 0.9 × 3 mm3 ) were obtained with a multishot T2 -prepared balanced steady-state free precession (T2 -prep-bSSFP) acquisition sequence using a 3D variable density undersampled Cartesian trajectory. Each T2 -weighted image was reconstructed using total variation regularized sensitivity encoding. A flexible simulation framework based on extended phase graphs generated a dictionary of magnetization signals, which was customized to the proposed sequence. The dictionary was matched to the acquired T2 -weighted images to retrieve quantitative T2 values, which were then compared to gold-standard spin echo acquisition values using monoexponential fitting. The proposed approach was validated in simulations and a T1 /T2 phantom, and feasibility was tested in 8 healthy subjects. RESULTS: The simulation analysis showed that the proposed T2 mapping approach is robust to noise and typically observed T1 variations. T2 values obtained in the phantom with T2 prep-bSSFP and the acquisition-specific, dictionary-based matching were highly correlated with the gold-standard spin echo method (r = 0.99). Furthermore, no differences were observed with the accelerated acquisition compared to the fully sampled acquisition (r = 0.99). T2 values obtained in prostate peripheral zone, central gland, and muscle in healthy subjects (age, 26 ± 6 years) were 97 ± 14, 76 ± 7, and 36 ± 3 ms, respectively. CONCLUSION: 3D quantitative T2 mapping of the whole prostate can be achieved in 3 minutes.

Late side effects of 3T MRI-guided 3D high-dose rate brachytherapy of cervical cancer : Institutional experiences.

PURPOSE: This article reports experiences with 3T magnetic resonance imaging(MRI)-guided brachytherapy (BT) for cervical cancer focusing on late side effects. METHODS: Between June 2012 and March 2017 a total of 257 uterovaginal BT administrations were performed in 61 consecutive patients with inoperable cervical cancer. All patients were treated with BT combined with external beam radiotherapy. RESULTS: The mean HR-CTV (high risk-clinical target volume) D90 was 87 ± 5.1 Gy equivalent dose corresponding to the conventional fractionation using 2 Gy per fraction (EQD2, range 70.7-97.9 Gy). The mean doses in OAR (organs at risk), namely rectum, sigmoid and bladder were D2 cm3rectum = 62.6 ± 6.9 Gy EQD2 (range 38.2-77.2 Gy), D2 cm3sigmoid = 66.2 ± 6.8 Gy EQD2 (43.2-78.6 Gy) and D2 cm3bladder = 75.1 ± 8.3 Gy EQD2 (58.2-92.6 Gy). There were no signs of late gastrointestinal (GI) toxicity in 49 patients, grade 3 toxicity was seen in 2 patients and grade 4 toxicity in 3 patients. There were no signs of late genitourinary (GU) toxicity in 41 patients, grade 3 toxicity was seen in 4 patients and no signs of grade 4 toxicity were seen. After the treatment, 60 patients (98.4%) achieved locoregional remission. In 54 patients (88.5%) the remission was complete, whereas in 6 patients (9.8%) remission was partial. CONCLUSION: The use of 3T MRI-guided BT leads to achievement of high rates of local control with limited late morbidity as demonstrated in this series of patients.

Modified MR dispersion imaging in prostate dynamic contrast-enhanced MRI.

BACKGROUND: An estimation of an intravascular dispersion parameter was previously proposed to improve the overall accuracy and precision of the model parameters, but the high computation complexity can limit its practical usability in prostate dynamic contrast-enhanced MRI (DCE-MRI). PURPOSE: To compare and evaluate the model fitting uncertainty and error in the model parameter estimation using different DCE-MRI analysis models and to evaluate the ability of the intravascular dispersion parameter to delineate between noncancerous and cancerous prostate tissue in the transition and peripheral zones. STUDY TYPE: Retrospective. POPULATION: Fifty-three patients who underwent radical prostatectomy. FIELD STRENGTH/SEQUENCE: 3 T/3D RF-spoiled gradient echo sequence. ASSESSMENT: The coefficient of variation was used to assess the model fitting uncertainty by adding random noise to the time-concentration curves, and the Akaike information criterion was used to assess the model fitting error. The parametric maps derived from four DCE-MRI analysis models were evaluated by evaluating the delineation between noncancerous tissue and prostate cancer or clinically significant prostate cancer. STATISTICAL TESTS: The receiver operating curve analysis was performed to compare the ability to delineate between noncancerous and prostate cancer tissue in the transition and peripheral zones. RESULTS: Both MR dispersion imaging (MRDI) and Weinmann analysis models had the maximum coefficient of variation in different tissue types, while the model fitting uncertainty of modified (m)MRDI was similar to the standard Toft model. In mMRDI, the model fitting error was minimum, and the delineation between noncancerous and clinically significant prostate cancer tissue was improved in both transition (area under the curve [AUC] = 0.92) and peripheral zones (AUC = 0.92), in comparison with MRDI (AUC = 0.89 and AUC = 0.85, respectively). DATA CONCLUSION: The mMRDI showed promising results in detecting prostate cancer while maintaining a similar model fitting uncertainty. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1307-1317.

Noncontrast free-breathing respiratory self-navigated coronary artery cardiovascular magnetic resonance angiography at 3 T using lipid insensitive binomial off-resonant excitation (LIBRE).

BACKGROUND: Robust and homogeneous lipid suppression is mandatory for coronary artery cardiovascular magnetic resonance (CMR) imaging since the coronary arteries are commonly embedded in epicardial fat. However, effective large volume lipid suppression becomes more challenging when performing radial whole-heart coronary artery CMR for respiratory self-navigation and the problem may even be exacerbated at increasing magnetic field strengths. Incomplete fat suppression not only hinders a correct visualization of the coronary vessels and generates image artifacts, but may also affect advanced motion correction methods. The aim of this study was to evaluate a recently reported lipid insensitive CMR method when applied to a noncontrast self-navigated coronary artery CMR acquisitions at 3 T, and to compare it to more conventional fat suppression techniques. METHODS: Lipid insensitive binomial off resonant excitation (LIBRE) radiofrequency excitation pulses were included into a self-navigated 3D radial GRE coronary artery CMR sequence at 3 T. LIBRE was compared against a conventional CHESS fat saturation (FS) and a binomial 1-180°-1 water excitation (WE) pulse. First, fat suppression of all techniques was numerically characterized using Matlab and experimentally validated in phantoms and in legs of human volunteers. Subsequently, free-breathing self-navigated coronary artery CMR was performed using the LIBRE pulse as well as FS and WE in ten healthy subjects. Myocardial, arterial and chest fat signal-to-noise ratios (SNR), as well as coronary vessel conspicuity were quantitatively compared among those scans. RESULTS: The results obtained in the simulations were confirmed by the experimental validations as LIBRE enabled near complete fat suppression for 3D radial imaging in vitro and in vivo. For self-navigated whole-heart coronary artery CMR at 3 T, fat SNR was significantly attenuated using LIBRE compared with conventional FS. LIBRE increased the right coronary artery (RCA) vessel sharpness significantly (37 ± 9% (LIBRE) vs. 29 ± 8% (FS) and 30 ± 8% (WE), both p < 0.05) and led to a significant increase in the measured RCA vessel length to (83 ± 31 mm (LIBRE) vs. 56 ± 12 mm (FS) and 59 ± 27 (WE) p < 0.05). CONCLUSIONS: Applied to a respiratory self-navigated noncontrast 3D radial whole-heart sequence, LIBRE enables robust large volume fat suppression and significantly improves coronary artery image quality at 3 T compared to the use of conventional FS and WE.

Edge detector-based automatic segmentation of the skin layers and application to moisturization in high-resolution 3 Tesla magnetic resonance imaging.

INTRODUCTION: Previous studies have demonstrated the feasibility to explore moisturization with quantification imaging based on T2 mapping. The aim of this study was to describe and validate the first robust automated method to segment the first layers of the skin. MATERIALS AND METHODS: Data were picked from a previous study that included 35 healthy subjects who underwent a 3T MRI (multi spin echo calculation T2-weighted sequence) with a microscopic coil on the left heel before and one hour after moisturization. The automatic algorithm was composed of the T2 map generation, a Canny filter, a selection of boundaries, and a local regression to delimitate stratum corneum, epidermis, and dermis. An automated affine registration was applied between the exams before and after moisturization. RESULTS: The failure rate of the algorithm was below 5%. Mean computation time was 139.12s. There was a significant and strong correlation between the automatic measurements and the manual ones for the T2 values (ρ: 0.905, P < 0.001) and for the thickness measurements (ρ: 0.8663; P < 0.001). For registration, mean of the Dice index was 0.64 [0.47; 0.80] and of the Hausdorff distance was 0.29 mm 95% CI: [0.28; 0.30]. CONCLUSION: The proposed automatic method to study the first skin layers in 3T MRI using micro-coils was robust and described T2 values and thickness measurements with a strong correlation to manual measurements. The use of an automated affine registration could also permit the generation of a mapping for a visual assessment of moisturization.

The relationship between patellofemoral arthritis and fat tissue volume, body mass index and popliteal artery intima-media thickness through 3T knee MRI

Background/aim: Evaluating the relationship of patellar chondromalacia with obesity, infrapatellar fat pad (IFP) volume and popliteal artery intima-media thickness (IMT). Materials and methods: A total of203 patients with different degree of patellar chondromalacia (103 male, 100 female) and 52 control subjects (19 male, 33 female) were included and grouped according to sex, age, body surface area (BSA), body mass index (BMI) and patellar chondromalacia classification. All measurements were completed with 3T magnetic resonance imaging (MRI). Articular cartilage and IFP volume were measured in saggital plane using double echo steady state (DESS) and DIXON sequences, respectively. Patellar cartilage damage was graded using modified outerbridge classification, and the relations among cartilage volume and BMI, BSA, IFP, IMT were statistically assessed. Results: Popliteal artery IMT showed an independent association with the prevalence of cartilage defects and IFP volumes (P ˂ 0.001). There was an association between BMI and IFP volumes (P ˂ 0.001). However, no differences were observed between IFP volume and different chondromalacia groups. When IFP measurements were corrected using individual BMI and BSA values, a positive correlation was found between control and advanced chondromalacia groups (P ˂ 0.001). Conclusion: This study demonstrates the relationship among obesity, IMT and chondromalacia and highlights this potential circle to develop effective treatments and inhibit the progression of chondromalacia.

Bisphosphonates intake and its association with changes of periarticular bone area and three-dimensional shape: data from the Osteoarthritis Initiative (OAI).

OBJECTIVE: To determine the association between bisphosphonate treatment with the change of periarticular bone area and three-dimensional (3D) shape in participants of the Osteoarthritis Initiative (OAI) study. DESIGN: Using propensity score (PS) matching method in females, 48 bisphosphonate users and 105 non-users, who were matched for osteoarthritis (OA) and osteoporosis (OP) related factors were included. Baseline and 24-month magnetic resonance imaging (MRI)-based periarticular bone area and 3D shape measurements were used. The association between bisphosphonate intake and 24-month interval changes of the periarticular bone area and 3D shape were evaluated using paired Wilcoxon signed rank test. We used conditional logistic regression models for determining the association between bisphosphonate intake and periarticular bone change, defined using the standard deviation of difference (SDD) and reliable change index (RCI) methods. P-values have been adjusted for multiple comparisons using Benjamini & Hochberg procedure and false discovery rate (FDR)-adjusted P-values were reported. RESULTS: The 24-month interval increases in the periarticular bone area in medial side of tibia were significantly greater in non-users than users (FDR-adjusted P-value: 0.002). There was an approaching significance trend for lower medial tibial periarticular bone area expansion in bisphosphonate users in comparison with non-users (For 1SDD change, odds ratio 95% confidence interval (OR (95% CI)): 0.514 (0.271-0.975), FDR-adjusted P-value: 0.085) (For 1.96RCI change, OR (95% CI): 0.552 (0.309-0.986), FDR-adjusted P-value: 0.085). CONCLUSIONS: Bisphosphonate intake was associated with a reduction in the odds (approaching but not achieving significance) of expansion periarticular bone area, specifically in the medial tibial sub-region.

Comparative reliability and diagnostic performance of conventional 3T magnetic resonance imaging and 1.5T magnetic resonance arthrography for the evaluation of internal derangement of the hip.

OBJECTIVE: To compare the diagnostic accuracy of conventional 3T MRI against 1.5T MR arthrography (MRA) in patients with clinical femoroacetabular impingement (FAI). METHODS: Sixty-eight consecutive patients with clinical FAI underwent both 1.5T MRA and 3T MRI. Imaging was prospectively analysed by two musculoskeletal radiologists, blinded to patient outcomes and scored for internal derangement including labral and cartilage abnormality. Interobserver variation was assessed by kappa analysis. Thirty-nine patients subsequently underwent hip arthroscopy and surgical results and radiology findings were analysed. RESULTS: Both readers had higher sensitivities for detecting labral tears with 3T MRI compared to 1.5T MRA (not statistically significant p=0.07). For acetabular cartilage defect both readers had higher statistically significant sensitivities using 3T MRI compared to 1.5T MRA (p=0.02). Both readers had a slightly higher sensitivity for detecting delamination with 1.5T MRA compared to 3T MRI, but these differences were not statistically significant (p=0.66). Interobserver agreement was substantial to perfect agreement for all parameters except the identification of delamination (3T MRI showed moderate agreement and 1.5T MRA substantial agreement). CONCLUSION: Conventional 3T MRI may be at least equivalent to 1.5T MRA in detecting acetabular labrum and possibly superior to 1.5T MRA in detecting cartilage defects in patients with suspected FAI. KEY POINTS: • Conventional 3T MRI is equivalent to 1.5T MRA for diagnosing labral tears. • Conventional 3T MRI is superior to 1.5T MRA for diagnosing acetabular cartilage defect. • Conventional 3T MRI is equivalent to 1.5T MRA for diagnosing cartilage delamination. • Symptom severity score was significantly higher (p<0.05) in group proceeding to surgery.

The relationship between myocardial and hepatic T2 and T2* at 1.5T and 3T MRI in normal and iron-overloaded patients.

Background Cardiac and liver iron assessment using magnetic resonance imaging (MRI) is non-invasive and used as a preclinical "endpoint" in asymptomatic patients and for serial iron measurements in iron-overloaded patients. Purpose To compare iron measurements between hepatic and myocardial T2* and T2 at 1.5T and 3T MRI in normal and iron-overloaded patients. Material and Methods The T2 and T2* values from the regions of interest (ROIs) at mid-left ventricle and mid-hepatic slices were evaluated by 1.5T and 3T MRI scans for healthy and iron-overloaded patients. Results For iron-overloaded patients, the myocardial T2 (1.5T) and myocardial T2 (3T) values were 60.3 ms (range = 56.2-64.8 ms) and 55 ms (range = 51.6-60.1 ms) (ρ = 0.3679) while the myocardial T2* (3T) 20.5 ms (range = 18.4-25.9 ms) was shorter than the myocardial T2* (1.5T) 35.9 ms (range = 31.4-39.5 ms) (ρ = 0.6454). The hepatic T2 at 1.5T and 3T were 19.1 ms (range = 14.8-27.9 ms) and 15.5 ms (14.6-20.4 ms) (ρ = 0.9444) and the hepatic T2* at 1.5T and 3T were 2.7 ms (range = 1.8-5.6 ms) and 1.8 ms (range = 1.1-2.9 ms) (ρ = 0.9826). The line of best fit exhibiting the linearity of the hepatic T2* (1.5T) and hepatic T2* (3T) had a slope of 2 and an intercept of -0.387 ms (R = 0.984). Conclusion Our study found myocardial T2 (1.5T) nearly equal to T2 (3T) with myocardial T2* (3T) 1.75 shorter than myocardial T2* (1.5T). The relationship of hepatic T2* (1.5T) and hepatic T2* (3T) was linear with T2* (1.5T) approximately double to T2* (3T) in iron-overloaded patients. This linear relationship between hepatic T2* (1.5T) and hepatic T2 (3T) could be an alternative method for estimating liver iron concentration (LIC) from 3T.

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and T2 mapping at 3T MRI of the wrist: Feasibility and clinical application.

PURPOSE: To assess the feasibility of delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and T2 mapping for biochemical imaging of the wrist at 3T. MATERIALS AND METHODS: Seventeen patients with wrist pain (mean age, 41.4 ± 13.1 years) including a subgroup with chondromalacia (n = 11) and 15 healthy volunteers (26.0 ± 2.2 years) underwent dGEMRIC and T2 mapping at 3T. For dGEMRIC, the optimum time window after contrast-injection (gadopentetate dimeglumine) was defined as the plateau of the T1 curve of repeated measurements 15-90 minutes postinjection and assessed in all volunteers. Reference values of healthy-appearing cartilage from all individuals and values in areas of chondromalacia were assessed using region-of-interest analyses. Receiver-operating-characteristic analyses were applied to assess discriminatory ability between damaged and normal cartilage. RESULTS: The optimum time window was 45-90 minutes, and the 60-minute timepoint was subsequently used. In chondromalacia, dGEMRIC values were lower (551 ± 84 msec, P < 0.001), and T2 values higher (63.9 ± 17.7, P = 0.001) compared to healthy-appearing cartilage of the same patient. Areas under the curve did not significantly differ between dGEMRIC (0.91) and T2 mapping (0.99; P = 0.17). In healthy-appearing cartilage of volunteers and patients, mean dGEMRIC values were 731.3 ± 47.1 msec and 674.6 ± 72.1 msec (P = 0.01), and mean T2 values were 36.5 ± 5 msec and 41.1 ± 3.2 msec (P = 0.009), respectively. CONCLUSION: At 3T, dGEMRIC and T2 mapping are feasible for biochemical cartilage imaging of the wrist. Both techniques allow separation and biochemical assessment of thin opposing cartilage surfaces and can distinguish between healthy and damaged cartilage. LEVEL OF EVIDENCE: 3 J. Magn. Reson. Imaging 2017;45:381-389.