MRI and CT venography in the diagnosis of hemodynamic disorders in patients suffering from the lower extremities veins chronic diseases Part I. Possibilities of MRI in visualization of the vascular blood flow of the lower extremities

Abstract

Despite the fact that most vascular surgeons in Russia rarely use magnetic resonance imaging (MRI) in their daily practice, today interest in this method of imaging among specialists in the world is steadily increasing. This is due to the desire of clinicians to have another non – invasive method for diagnosing hemodynamic disorders of both the arterial (Magnetic Resonance Angiography – MRA) and venous vascular bed (Magnetic Resonance Venography – VRA). The development of these methods today is associated with the solution of many technical problems, the development of special pulse sequences and post-processing methods for the resulting image. This literature review analyzes published scientific data on the methodology of MRI in relation to the vascular system and the choice of optimal scanning modes. Taking into consideration the fact that this material is intended primarily for vascular surgeons and phlebologists, and not radiologists, the first part summarizes the basic understanding of the physical phenomena underlying the MRI image, without which a thoughtful analysis of the advantages and disadvantages of MR-Angiography and the search for the most optimal scanning mode for MR-Venography is not possible. Based on the constant desire of clinicians to be self-educated, it seems that this part of the presented material will not be difficult to understand. When describing the developed contrast-free and contrast-free MRA methods, attention is paid to the traditional methods of image processing in 2D mode (TOF, PC) using pulse sequences: spin echo (SE), multi-echo (SE T2), turbo spin echo (TSE), fast Advanced Spin Echo (fast Advanced Spin Echo-FASE), gradient echo (Gradient Echo-GE, GRE) and inversion recovery (Inversion Recovery-IR). In addition, the focus is on the most modern solu tions, including: multiplantar reformatting (MPR), maximum intensity projection (MIP), subvolume maximum intensity, surface rendering (SR), volume rendering (VR) and virtual intraluminal endoscopy (VIE). For all the methods used today, MR-Angiography is shown to be specific and informative, with a detailed analysis of the advantages and disadvantages. The nuances of understanding the resulting angiographic image in T1 and T2-weighted images and the phenomena of “bright blood” and “black blood” are shown. Since the absence of information or a brief mention only about the possibilities of using MRI in the diagnosis of hemodynamic disorders in patients with vascular pathology in Russian scientific literature it seems that this material is relevant and will arouse some interest from various specialists. Of particular interest is the potential use of contrast-free and contrast – free MR Angiography in the study of venous pathology of the lower extremities and pelvis, especially with regard to timely and accurate diagnosis of deep venous thrombosis (deep Vein Thrombosis-DVT) and venous thromboembolism (Venous Thrombosis – Embolism – VTE), which occupy a special position in the structure of patients with chronic venous Disorders of the lower extremities (Chronic Venous Disorders-CVD).