Sažetak | Mamografija je dugo vremena koristila sustav filma i folije za dobivanje mamografskih slika, a prijelazom na FPD doživila je brojne prednosti. Iako je FFDM trenutno zlatni standard u dijagnostici bolesti dojke, brojna istraživanja naglašavaju prednosti DBT-a te se on uzima u obzir kao metoda koja bi mogla postati novi zlatni standard. Kod tomosinteze postoje tri vrste gibanja detektora i cijevi, a tomosinteza dojke koristi djelomično izocentrično gibanje. Ono podrazumijeva lučno gibanje rendgenske cijevi iznad nepomičnog detektora, odnosno rendgenska cijev se giba iznad detektora koji je komprimiran ispod dojke te tako stvara 3D prikaz dojke DBT pomicanjem rendgenske cijevi u luku iznad dojki slika niz projekcijskih slika pod različitim kutovima, a zatim rekonstruira puno tankih slojeva slike objekta. Zahvaljujući digitalnoj obrada slike moguće je rekonstruirati serije slojeva različitih debljina i na različitim dubinama te prikazati ono što je nevidljivo na konvencionalnoj radiografskoj snimci, brisanjem struktura koje se nalaze izvan sloja koji se prikazuje, odnosno dobiveni presjeci se mogu kombinirati za 3D (trodimenzionalnu) rekonstrukciju. Navedenim načinom tomosinteza uklanja problem 2D mamografije, odnosno uklanja preklapanje tkiva anatomskih struktura i pojačava vidljivost patoloških struktura na mamogramu. Pozicioniranje dojke provodi se kao kod konvencionalne mamografije, ali sa znatno slabijom kompresijom. Slabiji pritisak dojke tokom snimanja pacijenticama pruža veću ugodnost pretrage. Najčešće se dojka postavlja u uobičajene mamografske projekcije, odnosno MLO i CC, ali po potrebi se dojka može postavljati i u druge položaje. Kada je u pitanju rekonstrukcija, kakvoća slike i vrijeme trajanja rekonstrukcije su najvažniji kriteriji koji trebaju biti ispunjeni. Vrijeme rekonstrukcije mora biti što kraće za kliničku primjenu tomosinteze. Zbog brze rekonstrukcije slike uz očuvanje kvalitete slike dostojne sporijim metodama, Filtered Back Projection je najčešće korištena metoda rekonstrukcije u praksi. Tomosinteza povećava otkrivanje raka i korisna je za sve žene bez obzira na gustoću dojke, a posebice za žene s velikom gustoćom dojki za koje FFDM nije idealna metoda pregleda. Jedno istraživanje je pokazalo kako je dijagnostička točnost DBT-a u usporedbi s FFDM kod „ne-gustih“ dojki bila neznatno veća od DBT-a, oko 3%, dok je kod žena s gustim dojkama bila veća oko 8%. Potencijalne prednosti DBT-a su smanjenje stope ponavljanja screening mamografije, poboljšanje preoperativnog određivanja stadija raka te uklanjanje preklapajućih tkiva na 3D slikama. Sve to olakšava otkrivanje raka i poboljšava mamografsku osjetljivost što može smanjiti broj lažno pozitivnih nalaza i nepotrebnih biopsija. Unatoč kvalitetnijoj slici, smanjenoj dozi zračenja, skraćenju vremena za analizu slike te ostalim brojnim prednostima, pokazalo se da je odaziv na DBT pregled manji od odaziva na FFDM pregled. Kako bi se otkrio razlog manjeg odaziva provedena su istraživanja, a jedno od njih je pokazalo da su financijski troškovi pregleda imali najveći utjecaj na smanjeni odaziv kod DBT-a, s prosječnom ocjenom 4,68 od 5, dok su ostali ponuđeni razlozi odbijanja pregleda imali manji utjecaj na odluku pacijenta, s prosječnom ocjenom u rasponu od 1,53 do 1,72. Potencijalni trošak iz vlastitog džepa pacijenata jedan je od glavnih prepreka u uvođenju DBT-a kao standarda za probir raka dojke. |
Sažetak (engleski) | Mammography has used a film and foil system to record signals for a long time, and by transitioning to FPD it has experienced numerous benefits. Although FFDM is the current gold standard in the diagnosis of breast disease, numerous studies highlight the benefits of DBT, and it is being considered as a method that could become the new gold standard. In tomosynthesis, there are three possible ways of tube and detector movement, and DBT uses partially isocentric motion where a stationary detector is located below the compressed breast and the X-ray tube moves to create a three-dimensional view. By moving the X-ray tube into the arc above the breast images, DBT takes series of projection images at different angles, and then reconstructs a lot of thin layers of the image of the object. Thanks to digital image processing, it is possible to reconstruct series of layers of different thicknesses and depths and show what is invisible on a conventional radiographic image, by deleting structures outside the displayed layer, which results with cross sections that can be combined for 3D (three-dimensional) reconstruction. Tomosynthesis eliminates the problem of 2D mammography by removing the overlapping tissues of anatomical structures and increases the visibility of pathological structures on the mammogram. Breast positioning is performed as with conventional mammography, but with significantly less pressure. The breast is most often placed in the usual mammographic positions, which are MLO and CC, but it is possible to work in other necessary positions. When it comes to reconstruction, image quality and duration of reconstruction are the most important criteria to be met. The reconstruction time must be as short as possible for the clinical application of tomosynthesis. Due to the rapid reconstruction of the image while preserving the image quality worthy of slower methods, Filtered Back Projection is the most commonly used reconstruction method in practice. As for displaying the reconstructed layers on the screen, they can be viewed individually, or as ciné loop, which is a video where the layers change one after another. Tomosynthesis has increased the detection of cancer and is beneficial for all women regardless of breast density, and special attention is given to women with high breast density for whom FFDM is not an ideal screening method. One study found that the diagnostic accuracy of DBT compared to FFDM for non-dense breasts was slightly higher than that of DBT, about 3%, while in a woman with dense breasts it was about 8% higher. The potential benefits of DBT are lower recall rate, improved preoperative cancer staging and removal of overlapping tissues in 3D images. All of these benefits improved mammographic sensitivity, resulting in a reduction of false-positive findings and unnecessary biopsies. Despite the better image quality, reduced radiation dose, shorter image analysis time, and a number of other benefits, the response of patients to the DBT has been shown to be lower than the response of patients to the FFDM. There were conducted a survey to find out the reason for the lower response of patients to DBT, and one of them showed that the financial costs had the greatest impact on the reduced response of patients to DBT, with an average score of 4.68 out of 5, while the other offered reasons for refusing the DBT had less impact on patient decision, with a mean score ranging from 1.53 to 1.72. The potential cost out of patients ’own pockets is one of the main obstacles to the introduction of DBT as a standard for breast cancer screening. |