INJURED KNEE ( MRI 1, 5 T)

INTRODUCTION
Some time we heard information about knee injured in the sport like football. Much player football cannot playing because have knee injured. So he must go to hospital to rehabilitation in much time. In the first step to rehabilitation he must observed with MRI to know where located the injured to do action hereinafter. Magnetic Resonance Imaging (MRI) is a technique depiction of slice of body pursuant to magnetic resonance principle of hydrogen atom nucleus core. Techniques of depiction of MRI relative complex because yielded picture depend on many parameters. When the election of parameter is precisely, quality of detail picture of human being body will see clearly, so that body tissue pathology and anatomy can evaluate accurately. For that require comprehending by things related to technique procedure of MRI.

TECHNIQUE
Antecedent of Magnetic Resonance Imaging (MRI) represent recent imaging modalities which rapidly grow since application clinically at ± year 1980. Excess of this MRI are compared to former imaging modalities ( conventional, CT, USG) for example is ability present anatomy detail clearly in so many cutting (multiplanar) without altering patient position. Despitefully in inspection of MRI have the character of the non invasive, not generate to feel pain in bone and give good information about situation of soft tissue. Like its predecessor (CT scan), MRI also represent imaging modalities under colors of computer presenting cutting slices of body as us desire. Differ from CT scan which ionizing radiation using, hence in MRI relied on interaction among nucleus; core and radio wave of hydrogen body by existence of strong magnetic field. Since application clinically, MRI have expanded quickly and during brief relative have come to imaging modalities giving big contribution in diagnose specially in inspection of system musculoskeletal, bone marrow, cartilage, ligament, muscle, meniscus, etc. Principal base work of MRI relied on the happening of interaction between nucleus core and radio wave of hydrogen in body, which entered into strong magnetic field. Core which giving comments in MRI is the core of owning magnetic moment, namely the core of with amount of anomalous neutron or proton. In body tissue, core of with this for example core of hydrogen ( 1 H ), fluor ( 19 F), natrium ( 23 Na) and phosphorus ( 31 P). Compared with all existing element, hydrogen is simplest element, consist of 1 electron, 1 proton and without neutron. Therefore MRI applicated in hydrogen with consideration: Isotopic fallen of him are near 100 %, till give high sensitivities to MRI signal Biggest magnetic moment compared with] other element Naturally the amount of hydrogen in body tissue (especially in the form of fat and water) copious ( 2 / 3 part of body consist of water). Method inspection of MRI relative komplex because yielded radiograf depends on intrinsic parameter and extrinsic which we do not find in the inspection of conventional radiography. The forming of image of MRI can be described as following: If body positioned in strong magnetic field, core of body hydrogen will be unidirectional and rotated encircle direction / magnetic field vector. IWhen radio frequency signal transmitted to through body, some core of hydrogen will permeate energy of the radio frequency and chops round or equally perform a resonance. If radio frequency signal discontinued by this radiation, the nucleus cores will return on course initially, discharging energy which have been permeated and generate the capturer signal by antenna; then processed by computer in the form of radiograph. Brightness determined by radio frequency amplitude which returns from tissue. Thereby tissue contrast determined by difference of yielded MR signal from is assorted of tissue. Strength of MR signal relate to difference of atom amount between abnormal and normal tissue, that is time of relaxes T1 and of T2 and also stream factor. Contribution relative from the determinants at contrast of radiograph influenced by way of MR signal yielded that is election of tissue of pulse. With election of tissue of pulse correct difference between normal tissue or also identify abnormal tissue which is stake in normal tissue can be presented. One of the target of MR is how to manipulation of factor influencing tissue contrast, so that resulting the image with high diagnostic value. Image of MRI influenced by intrinsic parameter (cannot be altered) and parameter of extrinsic (earn relaxes change). Relaxes Time is parameter base of MRI to assess difference of tissue contrast. T1 (spin time relaxation lattice) is interaction between proton with around, assumed as absorbent efficiency of energy during relaxes. High efficiency, time of relaxes short (fat), and low efficiency of time of relaxes long (water). Short T2 (= fat), Long T2 (water). Time of Relaxes T1 and of T2 depends on status of biologic tissue, and every tissue has time of relapses different. Proton of Density is the amount of proton in one volume unit (proton = core of hydrogen). Amount of proton in air and bone little therefore do not give signal at MR and yield shadow / black picture. Image of MRI represent combination of PD, T1 and of T2, representing characteristic for tissue and referred as also as tissue parameter. Wight every tissue parameter can be altered with manipulation in tissue of pulse its international time and.
Every diagnostic technique of imaging aim to know morphology and demeanor of pathology process. To know about characteristic of morphologic from pathology process (location, size measure, form, extension, relation, and others) needed by 2 choice area that is area of imaging tissue and area of pulse. In the practice is used by third area of orthogonal (axial, sagital, coronal) and oblix, and also the amount of selected area depended to situation / organ anatomy and possibility of pathology. Beside that, every inspection needed T1 and of T2, because in the general characterization of pathology, the process can only assess on the combination image of T1 and of T2. Whatever of time of relaxes T1 and T2 that assessed, if transmitted signal is lower (hypo signal) called hypointens and give black picture, when its high radiation (hyper signal) called by hyperextend and give turn white picture. Air and of cortex bone give low signal at all network of pulse till always give black picture. For example, Technique of imaging knee is expected can give diagnostic information about :
Ligament in knee cover :

1. Transversum gender Ligament ( next side among lateralis meniscus and of meniscus medialis),
2. Menisci lateralis Ligamentum ( Wrisbergi) side behind from lateralis meniscus to lig. Posterius Cruciatum.
3. Lig. Pattelae and of patteale medial and lateral at ferrule joint side front, lig. Mediale Collateral of femoralis medialis condylus to medialis condylus and surface of media of tibia.
4. Lig. Collateral Lateral of backside of condylus femoralis laterales to side of lateral fibulae capitulum.
5. Lig. Popliteum Obliqum and of popliterum arcuatum side behind ferrule - joint. - Lig. Cruciata Anterius and of posterius in septum of Inter. Condylum Ligament

PARAMETER INSPECTION .
- Do slicing about 6-8 mm with matrix resolution high, in 3 area .

RESULT
- FSE / Turbo Rare T1Wi & T2Wi Sagital, notch intercondylar the to obliqe .

- FSE / Turbo Rare-Ir T2Wi free fat sagital .

- FSE / Turbo Rare T1Wi & T2Wi Aksial .

- FSE / Turbo Rare T1Wi & T2Wi Koronal .

- If indication have to use contrast using FSE / Turbo Rare T1Wi sagital, and aksial of koronal contrast post of Gd-DTPA
Team Meditec :
Sri Susilowati, the radiographer Karyadi’s Hospital Semarang, , Bali 18-20 Juli 2007