Diagnosis of heart disease by magnetic resonance imaging

Abstract

Magnetna rezonanca srca neinvazivna je dijagnosti čka tehnika koja je započela svoju kliničku uporabu ranih 1980-ih. Bazira se na principima nuklearne magnetne rezonance (NMR) koja se razvila 1930. godine. Bio je potreban značajan napredak od temeljnih principa NMR do generiranja slike ljudskog ti jela. Tehnike su se razvijale u svrhu detekcije male količine radiofrekventne energije (RF) generirane vrtnjom protona vodika kada je bolesnik u jakom magnetskom polju. Oslikavanje se danas temelji na jakim magnetskim poljima, supravodljivim magnetima i naprednoj elektronici koja usmjerava i obrađuje RF energiju. Osnovni izazov MR dijagnosti ke srca je kretanje srca ti jekom srčanog ciklusa i kretanje pluća ti jekom respiratornog ciklusa koji proizvode artefakte pokreta na slici. Dišni pokreti mogu biti ublaženi zadržavanjem daha ti jekom snimanja. Problem srčanih pokreta rješava se korištenjem EKG-a. EKG “gating” prikuplja podatke za oslikavanje samo u određenom dijelu srčanog ciklusa, obično za vrijeme dijastole. R val EKG-a koristi se kao referentna točka za prikupljanje podataka. Slike nastaju iz podataka prikupljenih u seriji srčanih ciklusa (R – R intervalima). Napretkom tehnike magnetna rezonanca srca postala je standardni pregled u procjeni regionalne i globalne sistoličke funkcije, detekcije infarkta miokarda i mogućnosti njegovog opravka, u analizi bolesti perikarda i tumora srca. U nekim centrima magnetna rezonanca srca je metoda izbora u detekciji ishemijske bolesti srca, kao i inicijalni pregled kod bolesnika s popuštanjem srčane funkcije. U članku su navedene indikacije i način izvođenja pregleda srca ovom metodom.Magneti c resonance imaging (MRI) is a noninvasive imaging technique that came into clinical use in the early 1980s. It is based on the principles of nuclear magneti c resonance (NMR) which was developed in the 1930s. Signifi cant advances were necessary to go from the basic principles of NMR to generati ng images of the human body. Techniques were developed to localize the small amount of radio frequency (RF) energy generated from spinning hydrogen protons when a pati ent is placed in a strong magneti c fi eld. Image production today relies upon magneti c fi elds created by superconducti ng magnets and sophisti cated electronics which manipulate and process the RF energy. The fundamental challenges of cardiac MRI imaging is the movement of the heart throughout the cardiac cycle and the movement of the lungs during the respiratory cycle which produce moti on arti facts in the image. Respiratory moti on can be alleviated with breath holding during imaging. The problem of heart moti on can be solved with the use of ECG gated imaging. ECG gati ng allows for stop moti on imaging by acquiring data only during a specifi ed porti on of the cardiac cycle, typically during diastole. The R wave of the ECG is used as a reference point with data acquisition being initi ated following a given delay aft er the R wave. Images are created from data collected over a series of cardiac cycles (R to R intervals). These improvements have led to recogniti on of cardiac MRI as the reference standard for the assesment of regional and global systolic functi on, detecti on of myocardial infarcti on, miocardial viability,and cardiac masses. In some centers cardiac MRI is emerging as the test of choice for the detecti on of ischemic heart disease,as well as for the initi al work-up of pati ents presenti ng with heart failure. This arti cle gives the review of indicati ons and procedures to perform cardiac MRI