[Femoroacetabular impingement in adolescents]. / Femoroazetabuläres Impingement beim Jugendlichen und Adoleszenten.

Femoroacetabular impingement syndrome (FAIS) is caused by a repetitive mechanical conflict between the acetabulum and the proximal femur, occurring in flexion and internal rotation. In cam impingement, bony prominences of the femoral head-neck junction induce chondrolabral damage. The acetabular type of FAIS, termed pincer FAIS, may be either due to focal or global retroversion and/or acetabular overcoverage. Combinations of cam and pincer morphology are common. Pathological femoral torsion may aggravate or decrease the mechanical conflict in FAI but can also occur in isolation. Of note, a high percentage of adolescents with FAI-like shape changes remain asymptomatic. The diagnosis of FAIS is therefore made clinically, whereas imaging reveals the underlying morphology. X­rays in two planes remain the primary imaging modality, the exact evaluation of the osseous deformities of the femur and chondrolabral damage is assessed by magnetic resonance imaging (MRI). Acetabular coverage and version are primarily assessed on radiographs. Evaluation of the entire circumference of the proximal femur warrants MRI which is further used in the assessment of chondrolabral lesions, and also bone marrow and adjacent soft tissue abnormalities. The MRI protocol should routinely include measurements of femoral torsion. Fluid-sensitive sequences should be acquired to rule out degenerative or inflammatory extra-articular changes.

Tumor DNA methylation profiles correlate with response to anti-PD-1 immune checkpoint inhibitor monotherapy in sarcoma patients.

BACKGROUND: Some sarcomas respond to immune checkpoint inhibition, but predictive biomarkers are unknown. We analyzed tumor DNA methylation profiles in relation to immunological parameters and response to anti-programmed cell death 1 (anti-PD-1) immune checkpoint inhibitor (ICI) therapy in patients with sarcoma. PATIENTS AND METHODS: We retrospectively identified adult patients who had received anti-PD-1 ICI therapy for recurrent sarcoma in two independent centers. We performed (1) blinded radiological response evaluation according to immune response evaluation criteria in solid tumors (iRECIST) ; (2) tumor DNA methylation profiling of >850,000 probes using Infinium MethylationEPIC microarrays; (3) analysis of tumor-infiltrating immune cell subsets (CD3, CD8, CD45RO, FOXP3) and intratumoral expression of immune checkpoint molecules (PD-L1, PD-1, LAG-3) using immunohistochemistry; and (4) evaluation of blood-based systemic inflammation scores (neutrophil-to-lymphocyte ratio, leucocyte-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, platelet-to-lymphocyte ratio). Response to anti-PD-1 ICI therapy was bioinformatically and statistically correlated with DNA methylation profiles and immunological data. RESULTS: 35 patients (median age of 50 (23-81) years; 18 females, 17 males; 27 soft tissue sarcomas; 8 osteosarcomas) were included in this study. The objective response rate to anti-PD-1 ICI therapy was 22.9% with complete responses in 3 out of 35 and partial responses in 5 out of 35 patients. Adjustment of DNA methylation data for tumor-infiltrating immune cells resulted in identification of methylation differences between responders and non-responders to anti-PD-1 ICI. 2453 differentially methylated CpG sites (DMPs; 2043 with decreased and 410 with increased methylation) were identified. Clustering of sarcoma samples based on these DMPs revealed two main clusters: methylation cluster 1 (MC1) consisted of 73% responders and methylation cluster 2 (MC2) contained only non-responders to anti-PD-1 ICI. Median progression-free survival from anti-PD-1 therapy start of MC1 and MC2 patients was 16.5 and 1.9 months, respectively (p=0.001). Median overall survival of these patients was 34.4 and 8.0 months, respectively (p=0.029). The most prominent DNA methylation differences were found in pathways implicated in Rap1 signaling, focal adhesion, adherens junction Phosphoinositide 3-kinase (PI3K)-Akt signaling and extracellular matrix (ECM)-receptor interaction. CONCLUSIONS: Our data demonstrate that tumor DNA methylation profiles may serve as a predictive marker for response to anti-PD-1 ICI therapy in sarcoma.

Impact of concentration and dilution of three macrocyclic gadolinium-based contrast agents on MRI signal intensity at 1.5T and 3T and different pulse sequences: results of a phantom study in human plasma.

BACKGROUND: Many factors influence the increase in signal intensity (SI) provided by magnetic resonance imaging (MRI) contrast media. PURPOSE: To assess the impact of different gadolinium concentrations and dilutions of three macrocyclic gadolinium-based contrast agents (GBCA) on SI. MATERIAL AND METHODS: This phantom study investigated gadobutrol, gadoteridol, and gadoterate in human plasma of a healthy donor pool at 37 °C. Different molar concentrations served to mimic conditions typically relevant for steady-state imaging; different dilutions served to mimic influence on first-pass bolus imaging. For SI measurement at 1.5T and 3T, we used two Magnetom Scanners (Siemens), applying the T1-weighted sequences Flash 2D/3D and VIBE. Regions of interest were placed on the central slice of the test vials. RESULTS: In the concentration series, gadobutrol showed the highest SI of all three GBCAs up to 2 mM, followed by gadoteridol and gadoterate. No major differences were seen between 1.5T and 3T. In the dilution series, gadobutrol showed the highest SI of all three GBCAs up to 10 mL/L. The highest effect was recorded with Flash 3D and VIBE at 3T. CONCLUSION: SIs measured in phantoms using three macrocyclic GBCAs strongly depend on their relaxivity and on the local concentration. The latter can be influenced-when comparing dilutions-by their initial concentration in their formulation. Furthermore, the pulse sequences and the chosen parameters have essential influence. At steady-state concentrations (≤2 mM) and first-pass bolus dilutions (up to 10 ml/L), gadobutrol showed highest SIs, followed by gadoterate and gadoteridol.

Soft Tissue Sarcoma Follow-up Imaging: Strategies to Distinguish Post-treatment Changes from Recurrence.

Soft tissue sarcomas encompass multiple entities with differing recurrence rates and follow-up intervals. The detection of recurrences and their differentiation from post-therapeutic changes is therefore complex, with a central role for the clinical radiologist. This article describes approved recommendations. Prerequisite is a precise knowledge of the current clinical management and surgical techniques. We review recurrence rates and treatment modalities. An adequate imaging technique is paramount, and comparison with previous imaging is highly recommended. We describe time-dependent therapy-related complications on magnetic resonance imaging compared with the spectrum of regular post-therapeutic changes. Early complications such as seromas, hematomas, and infections, late complications such as edema and fibrosis, and inflammatory pseudotumors are elucidated. The appearance of recurrences and radiation-associated sarcomas is contrasted with these changes. This systematic approach in follow-up imaging of soft tissue sarcoma patients will facilitate the differentiation of post-therapeutic changes from recurrences.

Therapy-Related Imaging Findings in Patients with Sarcoma.

Knowledge of imaging findings related to therapy administered to patients with sarcoma is pivotal in selecting appropriate care for these patients. Imaging studies are performed as surveillance in asymptomatic patients or because symptoms, including anxiety, develop. In addition to detection of recurrent disease and assessment of response to therapy, diagnosis of conditions related to therapy that may or may not need treatment has a marked positive impact on quality of life. The purpose of this review is to assist radiologists, nuclear physicians, and others clinicians involved in the diagnosis and treatment of these patients in recognizing imaging findings related to therapy and not to activity of the previously treated sarcoma. Imaging findings are time dependent and often specific in relation to therapy given.

Comparison of the Relaxivities of Macrocyclic Gadolinium-Based Contrast Agents in Human Plasma at 1.5, 3, and 7 T, and Blood at 3 T.

PURPOSE: The relaxivities of 3 macrocyclic gadolinium-based contrast agents (GBCAs) were determined in human plasma and blood under standardized and clinically relevant laboratory conditions. METHODS: The T1 relaxivity, r1, was determined in human plasma at 1.5, 3, and 7 T, and in human blood at 3 T at 37°C in phantoms containing 4 different concentrations of the macrocyclic GBCAs gadobutrol, gadoteridol, and gadoterate. An inversion recovery turbo spin echo sequence was used to generate images with several inversion times. The T1-times were obtained by fitting the signal intensities to the signal equation. r1 was obtained by a 1/y-weighted regression of the T1-rates over the concentration of the GBCAs. RESULTS: For gadobutrol, the obtained r1 [L/(mmol·s)] in human plasma at 1.5 T, 3 T, and 7 T, and in human blood at 3 T was 4.78 ± 0.12, 4.97 ± 0.59, 3.83 ± 0.24, and 3.47 ± 0.16. For gadoteridol, r1 was 3.80 ± 0.10, 3.28 ± 0.09, 3.21 ± 0.07, and 2.61 ± 0.16, and for gadoterate, 3.32 ± 0.13, 3.00 ± 0.13, 2.84 ± 0.09, and 2.72 ± 0.17. CONCLUSIONS: The relaxivity of gadobutrol is significantly higher than that of gadoteridol and gadoterate at all magnetic field strengths and in plasma as well as in blood, whereas that of gadoteridol was higher than gadoterate only in plasma at 1.5 and 7 T. This is in accordance with results from 3 previous studies obtained in different media.

Soft Tissue Tumors in Adults: ESSR-Approved Guidelines for Diagnostic Imaging.

Soft tissue sarcomas are rare, but early, accurate diagnosis with subsequent appropriate treatment is crucial for the clinical outcome. The ESSR guidelines are intended to help radiologists in their decision-making and support discussion among clinicians who deal with patients with suspected or proven soft tissue tumors. Potentially malignant lesions recognized by ultrasound should be referred for magnetic resonance imaging (MRI), which also serves as a preoperative local staging modality, with specific technical requirements and mandatory radiological report elements. Radiography may add information about matrix calcification and osseous involvement. Indeterminate lesions, or lesions in which therapy is dependent on histology results, should be biopsied. For biopsy, we strongly recommend referral to a specialist sarcoma center, where an interdisciplinary tumor group, with a specialized pathologist, radiologist, and the surgeon are involved. In sarcoma, a CT scan of the chest is mandatory. Additional staging modalities are entity-specific. There are no evidence-based recommendations for routine follow-up in surgically treated sarcomas. However, we would recommend regular follow-up with intervals dependent on tumor grade, for 10 years after the initial diagnosis.

Gadolinium-based magnetic resonance contrast agents at 7 Tesla: in vitro T1 relaxivities in human blood plasma.

UNLABELLED: PURPOSE/INTRODUCTION: The aim of this study was to determine the T1 relaxivities (r1) of 8 gadolinium (Gd)-based MR contrast agents in human blood plasma at 7 Tesla, compared with 3 Tesla. SUBJECTS AND METHODS: Eight commercially available Gd-based MR contrast agents were diluted in human blood plasma to concentrations of 0, 0.25, 0.5, 1, and 2 mmol/L. In vitro measurements were performed at 37 degrees C, on a 7 Tesla and on a 3 Tesla whole-body magnetic resonance imaging scanner. For the determination of T1 relaxation times, Inversion Recovery Sequences with inversion times from 0 to 3500 ms were used. The relaxivities were calculated. RESULTS: The r1 relaxivities of all agents, diluted in human blood plasma at body temperature, were lower at 7 Tesla than at 3 Tesla. The values at 3 Tesla were comparable to those published earlier. Notably, in some agents, a minor negative correlation of r1 with a concentration of up to 2 mmol/L could be observed. This was most pronounced in the agents with the highest protein-binding capacity. DISCUSSION/CONCLUSION: At 7 Tesla, the in vitro r1 relaxivities of Gd-based contrast agents in human blood plasma are lower than those at 3 Tesla. This work may serve as a basis for the application of Gd-based MR contrast agents at 7 Tesla. Further studies are required to optimize the contrast agent dose in vivo.

Unenhanced MDCT in patients with suspected urinary stone disease: do coronal reformations improve diagnostic performance?

OBJECTIVE: The objectives of our study were to assess whether coronal reformations improve the diagnostic performance of MDCT in patients with acute flank pain and suspected urinary stone disease; and to determine if performing such reformations from 3-mm-thick sections is sufficient or if it is necessary to perform reformations from thinner sections. MATERIALS AND METHODS: We included 147 consecutive patients (72 women and 75 men; mean age +/- SD, 58 +/- 18.1 years) with suspected urinary stone disease who underwent unenhanced MDCT. Scans were obtained with a 4 x 1 mm collimation and were reconstructed with a section thickness of 1.25 and 3 mm. We compared the diagnostic yield of 3-mm axial sections with that of coronal reformations reconstructed from 1.25- and 3-mm axial sections. Imaging data were evaluated in random order by two radiologists. The significance of the difference between the axial sections and coronal multiplanar reformations (MPRs) was tested for the number, size, and location of uroliths and for the presence of alternative diagnoses. The time required for review by both observers was recorded. RESULTS: We found uroliths in 72 patients. There was no difference between 3-mm axial sections and coronal reformations from 1.25-mm sections with regard to the number of detected stones (n = 264 for both protocols), whereas coronal reformations from 3-mm sections revealed significantly fewer calcifications (n = 255, p = 0.016). Coronal reformations did not improve the localization of calcifications. Review time, however, was significantly shorter for coronal reformations than for axial sections (p = 0.001); however, coronal reformations were less sensitive than axial sections for the detection of additional findings suggestive of alternative diagnoses in 16 (30%) of 53 patients. CONCLUSION: Coronal reformations from MDCT do not improve urinary stone detection but may reduce evaluation time; however, there is the danger of missing additional findings. Coronal reformations reconstructed from thick (i.e., 3-5 mm) axial sections may result in reduced detection of small stones and should therefore be avoided.

Improved preoperative evaluation of cerebral cavernomas by high-field, high-resolution susceptibility-weighted magnetic resonance imaging at 3 Tesla: comparison with standard (1.5 T) magnetic resonance imaging and correlation with histopathological findings--preliminary results.

OBJECTIVES: To compare high-field, high-resolution, susceptibility-weighted magnetic resonance imaging (3 Tesla [T] HR-SW-MRI) and standard (1.5 Tesla [T]) MRI for the detection of cerebral cavernomas. To evaluate the ability of 3 T HR-SW-MRI to visualize intralesional structures compared with standard (1.5 T) MRI, in correlation with histopathologic findings. MATERIALS AND METHODS: Seventeen patients with cerebral cavernomas underwent both standard (1.5 T) MRI (T1-SE, T2-TSE, T2*-GRE) and 3 T HR-SW-MRI (TR/TE 43.3/9.1 millisecond; 512 x 384 x 48 matrix; FOV 250 mm; SI 72 mm) at our institution. All MR images were evaluated by 3 radiologists in consensus for detectability, size (1 cm), and conspicuity (good, acceptable, poor) of the lesions at both field strengths, and for the presence of hypointense intralesional tubular structures. In 7 patients, MR findings were correlated with histopathologic findings. RESULTS: Both 3 T HR-SW-MRI and standard (1.5 T) MRI detected 22 lesions in 17 patients; 3 T HR-SW-MRI detected an additional 7 lesions in 6 patients. On average, 3 T HR-SW-MRI detected 1.706 +/- 0.92 (median = 1) lesions per patient, whereas standard (1.5 T) MRI detected 1.235 +/- 0.664 lesions per patient (P = 0.016). Lesion conspicuity was good in all 3 T HR-SW-MR images and good in 68.2% and acceptable in 31.8% of standard (1.5 T) MR images (P = 0.016). In 22 lesions detected at both field strengths, 3 T HR-SW-MRI demonstrated intralesional tubular structures in 72.7% and standard (1.5 T) MRI demonstrated these structures in 31.8% (P = 0.001). Intralesional tubular structure correlated to conglomerates of cavernous vessel, as verified by histopathology. CONCLUSION: Compared with standard (1.5 T) MRI, 3 T HR-SW-MRI allows superior detection and characterization of cerebral cavernomas. Despite increased susceptibility effects, ie, signal loss at higher magnetic field strengths, the visualization of intralesional tubular structures is feasible. This may be helpful in the diagnosis, presurgical planning, and noninvasive follow-up after gamma-knife radiosurgery.

MR imaging of the cervical spine: assessment of image quality with parallel imaging compared to non-accelerated MR measurements.

To compare the quality of cervical spine MR images obtained by parallel imaging [generalized autocalibrating partially parallel acquisition (GRAPPA)] with those of non-accelerated imaging, we conducted both phantom studies and examinations of ten volunteers at 1.5Tesla with a dedicated 12-element coil system and a head-spine-neck coil combination. Acquisitions included axial T2-weighted (T2w) images with both methods, and sagittal T2w and T1w images in vivo with the latter coil combination. Non-accelerated MRI with two averages and GRAPPA (acceleration factor 2) with two averages (GRAPPA/2AV, time reduction of approximately 50%) and four averages (GRAPPA/4AV) were compared. In the phantom, the signal-to-noise ratio of the GRAPPA/2AV was lower than that of the other two settings. In vivo, the image inhomogeneity (non-uniformity, NU) was significantly higher in T2w GRAPPA/2AV than in both other settings, and in T1w GRAPPA/2AV compared to GRAPPA/4AV. Subjectively, the delineation of anatomical structures was sufficient in all sequences. Only the spinal cord was considered to be better delineable on the non-accelerated T1w sequence compared to GRAPPA/2AV. In part, GRAPPA/4AV performed better than the other settings. The subjective image noise was lowest with GRAPPA/4AV. In cervical spine MRI, the examination time can be reduced by nearly 42% with GRAPPA, while preserving sufficient image quality.

Imaging articular cartilage defects in the ankle joint with 3D fat-suppressed echo planar imaging: comparison with conventional 3D fat-suppressed gradient echo imaging.

PURPOSE: To shorten the examination time for articular cartilage imaging, using a recently developed three-dimensional (3D) multishot echo planar imaging (EPI) sequence with fat saturated (FS), compared to a conventional 3D fat-saturated spoiled gradient echo sequence (3D FS GRE). MATERIAL AND METHODS: There were 32 consecutive patients with ankle joint disorders who underwent magnetic resonance imaging (MRI) in a 1.0-T unit. Hyaline cartilage was imaged with a 3D FS EPI sequence and a 3D FS GRE sequence. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, and image artifacts. In addition, contrast-to-noise ratios (CNRs) of cartilage vs. joint fluid and bone marrow were measured. RESULTS: The 3D FS EPI sequence provided a high CNR between cartilage and subchondral bone, similar to that of the 3D FS GRE sequence. The CNR between cartilage and effusion was significantly lower on the 3D EPI sequence due to the higher signal intensity of fluid. Both sequences were equal in lesion detection ability. The image quality of the 3D FS GRE sequence was slightly higher than that of the 3D FS EPI, but the difference was not statistically significant. CONCLUSION: We conclude that the 3D FS EPI sequence is comparable to the 3D FS GRE sequence in the detection of cartilage lesions, with the additional advantage of reduction in scan time by a factor of 4.