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Result : Searchterm 't1 stir' found in 0 term [] and 0 definition [], (+ 20 Boolean[] results
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Fat suppression is the process of utilizing specific MRI parameters to remove the deleterious effects of fat from the resulting images , e.g. with STIR, FAT SAT sequences, water selective (PROSET WATS - water only selection, also FATS - fat only selection possible) excitation techniques, or pulse sequences based on the Dixon method.
Spin magnetization can be modulated by using special RF pulses. CHESS or its variations like SPIR, SPAIR ( Spectral Selection Attenuated Inversion Recovery) and FAT SAT use frequency selective excitation pulses, which produce fat saturation.
Fat suppression techniques are nearly used in all body parts and belong to every standard MRI protocol of joints like knee, shoulder, hips, etc.
Image Guidance
Imaging of, e.g. the foot can induce bad fat suppression with SPIR/FAT SAT due to the asymmetric volume of this body part. The volume of the foot alters the magnetic field to a different degree than the smaller volume of the lower leg affecting the protons there. There is only a small band of tissue where the fat protons are precessing at the frequency expected, resulting in frequency selective fat saturation working only in that area. This can be corrected by volume shimming or creating a more symmetrical volume being imaged with water bags.
Even with their longer scan time and motion sensitivity, STIR (short T1/tau inversion recovery) sequences are often the better choice to suppress fat. STIR images are also preferred because of the decreased sensitivity to field inhomogeneities, permitting larger fields of views when compared to fat suppressed images and the ability to image away from the isocenter. See also Knee MRI.
Sequences based on Dixon turbo spin echo ( fast spin echo) can deliver a significant better fat suppression than conventional TSE/FSE imaging.
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From Philips Medical Systems;
Philips Infinion 1.5 T is designed to maximize the efficiency and quality of patient care. Developed with the patient in mind, the Infinion is the shortest and most open 1.5T scanner available. The unique 'ultra short' 1.4 m magnet assures patient comfort and acceptance without compromising image quality and clinical performance.
Device Information and Specification
CLINICAL APPLICATION
Whole body
CONFIGURATION
Ultra short bore
Head, head / neck, integrated C-spine, L/T spine array, small large GP coils, body flex array, torso pelvis array, breast array, endocavitary, shoulder array, lower extremity, hand / wrist, cardiac, PV array
SE, TSE, SS TSE, EPI, IR, STIR, FLAIR, FFE, TFE, T1 TFE, T2 TFE, Presat, Fatsat, MTC, Diff-opt., Angiography: PCA, MCA, TOF
IMAGING MODES
Single slice, single volume, multi slice, multi volume
80 images/sec std.; up to320 opt.@256
H*W*D
233 (lead fitted) x 198 x 140 cm
POWER REQUIREMENTS
400/480 V
COOLING SYSTEM TYPE
Closed loop, chilled water
| | | | • View the DATABASE results for 'Infinion 1.5T™' (2).
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Knee MRI, with its high soft tissue contrast is one of the main imaging tools to depict knee joint pathology. MRI allows accurate imaging of intra-articular structures such as ligaments, cartilage, menisci, bone marrow, synovium, and adjacent soft tissue.
Knee exams require a dedicated extremity coil, providing a homogenous imaging volume and high SNR to ensure best signal coverage.
A complete knee MR examination includes for example sagittal and coronal T1 weighted, and proton density weighted pulse sequences +/- fat saturation, or STIR sequences. For high spatial resolution, maximal 4 mm thick slices with at least an in plane resolution of 0.75 mm and small gap are recommended. To depict the anterior cruciate ligament clearly, the sagittal plane has to be rotated 10 - 20° externally (parallel to the medial border of the femoral condyle). Retropatellar cartilage can bee seen for example in axial T2 weighted gradient echo sequences with Fatsat. However, the choice of the pulse sequences is depended of the diagnostic question, the used scanner, and preference of the operator.
Diagnostic quality in knee imaging is possible with field strengths ranging from 0.2 to 3T. With low field strengths more signal averages must be measured, resulting in increased scan times to provide equivalent quality as high field strengths.
More diagnostic information of meniscal tears and chondral defects can be obtained by direct magnetic resonance arthrography, which is done by introducing a dilute solution of gadolinium in saline (1:1000) into the joint capsule. The knee is then scanned in all three planes using T1W sequences with fat suppression. For indirect arthrography, the contrast is given i.v. and similar scans are started 20 min. after injection and exercise of the knee.
Frequent indications of MRI scans in musculoskeletal knee diseases are: e.g., meniscal degeneration and tears, ligament injuries, osteochondral fractures, osteochondritis dissecans, avascular bone necrosis and rheumatoid arthritis. See also Imaging of the Extremities and STIR. | | | | | | • View the DATABASE results for 'Knee MRI' (4).
| | | • View the NEWS results for 'Knee MRI' (4).
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Quick Overview
DESCRIPTION
Signal loss, intensity variations
Image Guidance
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| | | | | | • View the DATABASE results for 'Black Blood MRA' (6).
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