Types of gradient echo sequences There is no refocusing 180° pulse and the data are sampled during a gradient echo, which is achieved by dephasing the spins with a negatively pulsed gradient before they are rephased by an Study with Quizlet and memorize flashcards containing terms like The type of pulse sequence that uses a gradient instead of a 180 degree RF pulse to rephase dephasing nuclei is known as _____. a. 1 The gradient echo The type of sequence Philips Siemens GE Hitachi Toshiba The gradient echo FFE GRE GRE GE FE Two significant points differentiate the gradient echo sequences and the SE sequences. Ability of users to identify ICH presence, type, and age on GRE was compared from the pretest to posttest timepoint. As a result of this versatility and the ability to acquire images in either 2D or 3D modes, spoiled-GRE sequences are now ubiquitously used for MR imaging of virtually every body part. spin echo b. These RF-pulses are often chosen to have flip angles (α) less than 90°, but can have any value. Each type of gradient-echo (GE) sequence consists of a train of excitation pulses that are separated by a constant time interval (TR). Recent studies have demonstrated that gradient echo (GRE) MRI sequences are as accurate as CT for the detection of intracerebral hemorrhage (ICH) in the context of acute stroke. fast spin echo d. These methods lead to four basic types of coherent gradient echo sequences in the table below. centric phase-encoding). The major purposes behind the gradient technique is a significant reduction in scan time. When imaging the female pelvis, the most optimal view for evaluation of the ovaries is the: Pulse Sequences: Rapid Gradient Echo M229 Advanced Topics in MRI Holden H. Dynamic enhanced MRA sequences of the mesenteric arteries are performed using: calibration scan. For each gradient echo sequence type, examples of applications exploiting the specific properties of the individual technique are presented. Gradient echo pulse sequences Conventional gradient echo Uses variable flip angles so that, TR and therefore the scan time, can be reduced without producing saturation. The difference between a FFE and TFE other than the speed of the sequence (GRE - sequence) A gradient echo is generated by using a pair of bipolar gradient pulses. Modern diffusion-weighted (DW) sequences all trace their origin to the pulsed gradient spin echo (PGSE) technique developed by Edward Stejskal and John Tanner in the mid-1960's. Probably most accurately they are grouped according to the type of sequence (e. #Phase encodings / ETL. With these sequences, we obtain ultrafast (roughly one second per slice), and robust imagery with a liquid / tissue contrast and an excellent signal to noise ratio. If these echoes are synchronized with the vibration, each readout's gradient lobes achieve a MEG-like effect, and the later generated echo causes a greater MEG-like effect. The formation of a GRE is illustrated schematically. , GRASS/FISP), flow sensitivity can be increased by using moderate-to-large flip angles. Gradient echo sequences like FLASH, SPGR, and FFE are used to generate T1-weighted images and can be applied (GRE - sequence) A gradient echo is generated by using a pair of bipolar gradient pulses. There are two types of MR pulse sequences, spin echo (SE) and gradient recalled echo (GRE); all other sequences are variations of these, with different parameters added on. The sequence was tested for the Handbook of MRI Pulse Sequences. Inversion-recovery also increases weighting of the associated imaging sequence (spin echo or gradient echo of varying speeds). If care is taken not to completely disrupt (spoil) these transverse coherences through the imaging process, it is possible to use dephase-rephase gradients to refocus and record the FID and Echo signals individually or in various MRI spin echo pulse sequences - Download as a PDF or view online for free INTRODUCTION Pulse sequences enable us to control the way in which the system applies pulses and gradients. Depending on what signal is used to form the images, SS sequences are divided into 3 types: 21. The phases of stationary spins are unaffected by the DG pair since any Pulse Sequences Here we cover the formation of the MR signal along with the four most commonly used pulse sequences Spin Echo Inversion Recovery Gradient Echo Susceptibility Imaging Diffusion: Basic Diffusion: Advanced Fat-Water Imaging In a gradient-echo type multi-echo MR sequence, several images are produced from each echo of the train with different echo times (TEs). In terms of display, two possibilities exist : The paramagnetic effects of deoxyhemoglobin (present in high concentrations in venous blood) significantly shortens T2 and T2* in the vicinity of veins. In cardiac imaging, ‘black blood’ spin echo images are used for anatomical imaging, while ‘bright blood’ imaging is used to study function and is based on gradient echo or hybrid echo sequences. In this way, and each is Objective: Contrast-enhanced fat-suppressed T1 weighted (T1W) two-dimensional (2D) turbo spin echo (TSE) and magnetization-prepared gradient echo (MPRAGE) sequences with water excitation are routinely obtained to evaluate orbit pathology. While this initially results in a smaller transverse magnetisation, as only a proportion of the z-magnetisation is transferred into the xy plane, the recovery of the z-magnetisation towards the equilibrium value is faster, allowing the This document provides an overview of MRI gradient echo pulse sequences, types, and applications. A gradient instead of 180 rephasing RF pulse is used to rephase the FID. Gradient echo (GRE) sequences begin as a regularly spaced series of radiofrequency (RF)-pulses repeated at time interval TR. Figure 1. There are two main sequence families, depending on the type of echo recorded: spin echo sequences, characterized by the presence of a 180° rephasing RF pulse; gradient echo sequences. Rapid imaging acquisition allows it to be applied to 2D and 3D MRI imaging. Therefore, it may be affected by the respiratory An MRI pulse sequence is a programmed set of changing magnetic gradients. A negative G FE is applied. This document provides an overview of MRI gradient echo pulse sequences, types, and applications. Residual transverse magnetization is spoiled in incoherent GRE sequences after signal acquisition so that it will not interfere in the next cycle. Diffuse vascular injury visible at SWI consists of convergent-type hemorrhages in the supratentorial white matter OBJECTIVE. Since spins at physically different locations along the gradient direction experience a range of rotation frequencies, when the Gradient echo (GRE) sequences begin as a regularly spaced series of radiofrequency (RF)-pulses repeated at time interval TR. Small flip angle are employed, which in turn allow very short repetition time thus decreasing the scan time. Large flip angles accentuate the signal from flowing blood or CSF for two reasons: (1) they cause more Gradients for spatial encoding (2D or 3D), whose arrangement will determine how the k-space is filled; A signal reading, combining one or a number of echo types (spin echo, gradient echo, hahn echo, stimulated echo) determining the type of contrast (the varying influence of relaxation times T1, T2and T2*). This chapter explains the characteristics of an MRI sequence, their classification and types in detail. Varieties of sequences from these four categories are available for clinical application. inversion recovery c. [1] The four basic MR (TFE) Turbo field echo is a gradient echo pulse sequence with data acquisition after an initial 180° (similar to IR) preparation pulse for contrast enhancement. g. 5 There are two primary differences between spin-echo and 10-06 Gradient Echo Sequences. Gradient echo uses magnetic gradients to generate a signal, instead of using 180 degrees radiofrequency pulse Free online course - There are two main sequence families, depending on the type of echo recorded: spin echo sequences and gradient echo sequences. Gradient-echo sequences generally consist of repeated RF pulses with a spacing TR, and imaging gra-dients. J In a pilot study including 64 patients with different types of brain tumors we investigated four types of MP-RAGE sequences. The choice of pulse sequence and it’s imaging parameters, including the timing parameters, repetition time, TR and echo time, TE determine the intrinsic strength of the MR signal from a particular tissue according to its proton density value and relaxation A spin echo (SE) is produced by pairs of radiofrequency (RF) pulses, whereas a gradient echo (GRE) is produced by a single RF pulse in conjunction with a gradient reversal. J An MRI pulse sequence is a programmed set of changing magnetic gradients. It discusses the basics of spatial encoding using slice selection, phase encoding, and frequency encoding gradients. 2). Basic Gradient Echo Sequence • FID Decay due to – T2 decay – Spin dephasing • Gradients accelerate spin dephasing. The purpose of this study is to compare the image quality, including artifacts, of a T1-weighted gradient-recalled echo (GRE) MRI sequence with a radial sampling approach to that of both 2D turbo spin-echo For steady-state GRE sequences (e. Two RF pulses at the same excitation Gradient echo sequences (GRE) are an alternative technique to spin-echo sequence s, differing from it in two principal points: utilization of gradient fields to generate transverse magnetization; flip angles of less than Free online course - Description of MRI sequences: spin echo, gradient echo, planar echo. We confirmed that the study by Middlebrooks et al is of great clinical value. Only FID(S+) is used for Finally, it is becoming more common in gradient-echo sequences to use multiecho or Dixon-type methods (61-63) for fat/water separation. utility of T2*-weighted gradient echo Further, the most common three variants of fast gradient echo sequences (TR < T 2), namely, unbalanced gradient echo, RF spoiled gradient echo, and balanced steady state free precession; are discussed. Key Words: gradient echo; balanced SSFP; steady state free precession; RF-spoiling Further, the most common three variants of fast gradient echo sequences (TR < T 2), namely, unbalanced gradient echo, RF spoiled gradient echo, and balanced steady state free precession; are discussed. A Two main classes of gradient echo sequence can be distinguished, depending on how residual transverse magnetiztion is managed : steady state gradient echo sequences that conserve residual transverse magnetization and therefore A gradient echo (GRE) is simply a clever manipulation of the FID signal that begins by applying an external dephasing gradient field across the specimen or tissue. Gradient echo (GRE) sequences are frequently used in clinical MRI to provide images with magnetic susceptibility contrast, such as T 2 *-weighted, phase [1–4] and susceptibility-weighted images (SWI) [5–7], R 2 * mapping and quantitative susceptibility mapping (QSM) [4, 8–10]. Oxford: Elsevier, 2004, pp 267-297. The gradient echo is generated Gradient echo sequences requiring high signal from fluid are known as all of the following EXCEPT: incoherent gradient echo. The RF flip angle (a) is usually constant, while the phase angle (f) can be constant, or can increment linearly or quadratically with the repetition number. For rapid steady-state sequences, an advantage of these approaches is that they do (GRE - sequence) A gradient echo is generated by using a pair of bipolar gradient pulses. A train of evenly spaced RF pulses produce "FID-like" and "Echo-like" signals. Gradient echo uses magnetic gradients to generate a signal, instead of using 180 degrees radiofrequency pulse like spin echo; thus leading to faster image acquisition time. When imaging the female pelvis, the most optimal view for evaluation of the ovaries is the: 5. The drawback of a small flip angle and very short TR is poor T1-weighting To obtain T2-weighting, the preparatory pattern is of the spin echo type (90 Steady-state sequences are a class of rapid magnetic resonance (MR) imaging techniques based on fast gradient-echo acquisitions in which both longitudinal magnetization (LM) and transverse magnetization (TM) are kept constant. If the findings on routine MRI sequences or even epilepsy-dedicated MRI seq Further, the most common three variants of fast gradient echo sequences (TR < T 2), namely, unbalanced gradient echo, RF spoiled gradient echo, and balanced steady state free precession; are discussed. (CDC), what type of isolation precautions should be used for HIV-positive patients in the MRI suite? coronal. ) however for non radiologists another There are two broad categories of GRE sequences: incoherent (spoiled residual transverse magnetization) and coherent (refocused transverse magnetization). The recorded signal simultaneously cumulates the free induction signal (FID) and that of the spin/stimulated echo. The major purpose behind the gradient technique is a significant reduction in scan time. The broad four categories of sequences include spin echo (SE), gradient echo (GRE), inversion recovery (IR) and echoplanar imaging (EPI). Each sequence will have a number of parameters, and multiple sequences grouped together into an MRI protocol. This last case applies to most rapid gradient-echo sequences. In these chapters, the evolution from a basic GRE sequence sampling data during free induction decay (FID) to more complex pulse sequences combining both gradient echo and spin echo features is explained. Gradient echo sequences are a type of MRI pulse sequence that utilizes gradient fields to generate echoes from the spins of protons in a magnetic field, allowing for the creation of images with varying contrast and resolution. Materials and Methods: Balanced turbo field echo (b-TFE; Philips Medical Systems, Best, The Netherlands) was investi-gated in vitro at a range of T2/T1 along with T1-contrast Gradient echo sequences requiring high signal from fluid are known as all of the following EXCEPT: incoherent gradient echo. A gradient is quicker to apply than a 180 pulse Therefore the minimum TE can An MRI pulse sequence is a programmed set of changing magnetic gradients. 11 Department of Radiological Sciences David Geffen School of Medicine at UCLA Some manufacturers, including Philips and Canon, use FE or FFE (fast field echo) to name their gradient echo sequences. The spins dephase, some faster than Gradient echo imaging is one of the fundamental imaging sequences used in cardiovascular applications. INTRODUCTION TO CONVENTIONAL GRADIENT ECHO PULSE SEQUENCE The gradient echo pulse sequence is the simplest type of MRI sequence. The acquisition and the spatial Fouri-er encoding of the gradient echo is performed between consecutive excitation pulses by means of switched gra-dient pulses along read, phase, and slice direction. As we mentioned before, the MRI scanner contains three gradient coils to build a gradient field in three orthogonal directions, x-, y-, and z-axis inside the magnet bore [59, 158, 159]. In a Fast Before introducing the gradient echo pulse sequence, we need to discuss the gradient coils in the magnet. The gradient echo forms the If care is taken not to completely disrupt (spoil) these transverse coherences through the imaging process, it is possible to use dephase-rephase gradients to refocus and record the FID and Echo signals individually or in various combinations. Basic Gradient Echo Sequence • FID Decay due to – T2 decay – Spin dephasing • Gradients accelerate spin dephasing • Gradients can undo gradient induced spin dephasing RF Slice This is a gradient echo sequence. T1 sequences will have grey matter being darker than white matter GRASS/FISP sequences are among the oldest and simplest of the steady-state coherent gradient echo sequences. Objective: The aim of this study is to evaluate a real-time magnetic resonance imaging (MRI) method that not only promises high spatiotemporal resolution but also practical robustness in a wide range of scientific and clinical applications. Numerous variations have been developed Free online course - Description of MRI sequences: spin echo, gradient echo, planar echo. Key Words: gradient echo; balanced SSFP; steady state free precession; RF-spoiling This overview briefly traces the history and nomenclature of gradient-recalled-echo (GRE) techniques used in magnetic resonance (MR) imaging. The drawback of a small flip angle and very short TR is poor T1-weighting To obtain T2-weighting, the preparatory pattern is of the spin echo type (90 In this type of echo gradient sequence, image weighting will depend on: the flip angle for T1 weighting (the greater the angle, the more T1 weighting) the TE for T2* weighting (the shorter the TE, the more T2* deweighting). which in turn allow very short repetition time thus Free online course - Ultrafast gradient echo sequences use a small flip angle, a very short TR and optimized k-space filling to reduce acquisition time (to roughly one second per slice). Materials and methods: The proposed method relies on highly undersampled gradient-echo sequences with radial encoding schemes. A comparison of magnetization prepared 3D gradient-echo (MP-RAGE) sequences for imaging four categories of sequences include spin echo (SE), gradient echo (GRE), inversion recovery (IR) and echoplanar imaging (EPI). RF Slice Select Phase Encode Freq. Type I consists in a lesion with subacute hemorrhage and it is characterized by a hyper-intense core on T1 and hyper Sequences are divided into different types: gradient echo, spin echo, and hybrid echo sequences. It describes coherent gradient echo sequences which maintain transverse magnetization between excitations, and incoherent sequences Free online course - Ultrafast gradient echo sequences use a small flip angle, a very short TR and optimized k-space filling to reduce acquisition time (to roughly one second per slice). 11 Department of Radiological Sciences David Geffen School of Medicine at UCLA Introduction. The frequency encoding gradient is used for this purpose. Gradient echo sequences (GRE) are an alternative technique to spin-echo sequence s, differing from it in two principal points: Compared to the spin-echo and inversion recovery sequences, gradient echo sequences are more versatile. At the INTRODUCTION TO GRADIENT ECHO PULSE SEQUENCE The gradient echo pulse sequence is the simplest type of MRI sequence. A spin echo is produced. The magnitude of the gradient fields are characterized as \(G_x\), \(G_y\), FIGURE 17-3 The gradient echo pulse sequence is shown. The radial-volume-interpolated breath-hold examination (VIBE) sequence The 3D-EDGE sequences show a higher sensitivity for FCD detection in epilepsy patients compared with a series of epilepsy-dedicated MRI protocols. based on MR imaging findings on conventional spin-echo and GRE sequences. The large family of steady-state gradient echo sequences can be classified into several groups: spoiled (or incoherent) steady-state sequences (where a spoiler gradient is used to dephase and cancel from the final signal the TM; sequence acronyms: FLASH, SPGR, T1-FFE), postexcitation refocused steady-state sequences (where only FID is used for . Whereas any gradient-echo sequence can be reconstructed to produce magnitude and phase images, the diagnostic information in phase data is often corrupted by the effects of air and/or tissue interfaces and phase aliasing. spin echo, or inversion recovery etc. J Chapters 40, 41, 55, and 56 discuss four different basic types of gradient echo (GRE) sequences routinely applied in clinical practice. Following the RF pulse, the first negative-going lobe of the gradient causes a phase dispersion of the precessing spins. Small variable flip angle are employed , usually less than 90 degrees. Radiology 1993; 186:1-8. Each line represents an activity, such as application of a gradient, an RF pulse, or performing signal detection. This is mainly because it lends itself easily to cine imaging, and is therefore used in applications that assess Gradient echo sequences (GRE) are an alternative technique to spin-echo sequence s, differing from it in two principal points: utilisation of gradient fields to generate transverse magnetisation; flip angles of less than 90° Compared to the spin-echo and inversion recovery sequences, gradient echo sequences are more versatile. As longitudinal regrowth speed is characterized by relaxation time T1, these sequences are weighted in T1. When parallel imaging techniques are utilized, a low resolution _____ is acquired prior to the acquisition. Ernst RR, Anderson WA. Another synonym is gradient-recalled echo (GRE). cession sequence (b-SSFP) under a large range of condi-tions and to compare its performance with other types of gradient echo sequences for dynamic imaging. Although they are not as frequently used in their pure forms any more (having been largely replaced by TrueFISP and other "balanced" sequences), understanding how they create an MR signal and those signal properties are still very instructive. These sequences allows for fast 3D imaging during short apnea (10 to 20 seconds). Results: A total of 104 users completed the 5. Gradient echo sequences are also used clinically to obtain faster 3-D images, as discussed above. Gradient-echo imaging was introduced in 1985 by Frahm and Haase as a way to speed image acquisition. ) however for non radiologists another An MRI sequence is a number of radiofrequency pulses and gradients that result in a set of images with a particular appearance. They have different This type of degenerative change is most common in the knee joint. The major purpose behind the gradient technique is a significant reduction in scan time Small flip angle are employed, which in Each type of gradient-echo (GE) sequence consists of a train of excitation pulses that are separated by a constant time interval (TR). The gradient echo pulse sequence uses an excitation pulse with a flip angle, α, that is normally less than 90° and typically 30° or less (Fig. Because the gradient echo sequence often uses the low-angle shot, the echo amplitude is often less than that of the SE sequence; thus, the GRE sequence image inherent signal-to-noise ratio is lower compared to the SE sequence. 17-2). . The sequences differ in the length of the recovery period and the data acquisition mode (sequential vs. In musculoskeletal clinical imaging, a faster type of gradient echo sequence (the FLASH sequence variant in TABLE 2, for example) is used routinely to examine for articular cartilage defects, due to the shorter possible TE times. Hahn echo. They have different contrast mechanisms, spatial and contrast resolution and speed of ac-quisition. However, these sequences can be marred by artefacts. These By applying a positive gradient for a time period, and following it by a negative gradient, we can appreciate that the spins initially advance in phase in the positive gradient and reverse in phase in the negative gradient (see Fig. GRE sequences, which are now offered commercially by 11 major manufacturers of MR imagers, are presented to illustrate their structural similarities and subtle differences in implementation. Within these families, numerous variations have been developed, mainly to increase acquisition speed 2), namely, unbalanced gradient echo, RF spoiled gradient echo, and balanced steady state free pre-cession; are discussed. These sequences are characterized by their short echo times (TE) and the use of gradient reversals rather than radiofrequency (RF) pulses to refocus spins, Gradient echo pulse sequences use gradient coils to alter the magnetic field strength along different axes within the MRI scanner. Rapid imaging acquisition allows it to be applied to 2D and 3D MRI imaging. As shown in the diagram right, symmetric, strong diffusion-sensitizing gradients (DG's) are applied on either side of the 180°-pulse. These imaging methods are sensitive to myelin in white matter and iron in Gradient echo pulse sequence and its application - Download as a PDF or view online for free (S-). The Some manufacturers, including Philips and Canon, use FE or FFE (fast field echo) to name their gradient echo sequences. D. The two main types of pulse sequence are gradient echo and spin echo pulse sequences. RF pulse applied; Slice-select gradient applied; Phase-encoding gradient applied; Frequency-encoding gradient applied. Encode Free Induction Decay (FID) Spoiled Gradient Echo Contrast Type of Contrast TE Further, the most common three variants of fast gradient echo sequences (TR < T 2), namely, unbalanced gradient echo, RF spoiled gradient echo, and balanced steady state free precession; are discussed. For each gradient echo sequence type, examples of applications exploiting the specific properties of the individual technique are presented. 2019. There are three main gradient coils that can selectively modify the field in the x, y, and z directions. Wu, Ph. Imaging time can drop from several minutes per standard SE image to seconds or even milliseconds. The first RF pulse is applied by the system in conjunction with the slice selection gradient, and is the combination that is responsible for accomplishing slice selection. With this type of sequence, certain tissues have a negative signal. 04. There is no refocusing 180° pulse and the data are sampled during a gradient echo, which is achieved by dephasing the spins with a negatively pulsed gradient before they are rephased by an GRADIENT ECHO The gradient echo pulse sequence is the simplest type of MRI sequence. 11. In the pulse sequence timing diagram, the basic gradient echo sequence is illustrated. They are used in angiography after Pulse Sequences: Rapid Gradient Echo M229 Advanced Topics in MRI Holden H. gradient echo, Which of the following is a disadvantage of fast spin echo pulse sequence/ a. In these chapters, the evolution from a basic GRE sequence Knowledge about sequence properties is essential to plan and acquire a diagnostic MRI examination. What happens if a gradient is turned on after the FID has spontaneously decayed? A gradient recalled echo is produced. Gradient echo is a magnetic resonance imaging (MRI) sequence that has wide variety of applications, from magnetic resonance angiography to perfusion MRI and diffusion MRI. The stimulus pulse, identified with the flip angle (90° with a "classic" SE) is usually selected as lower than 90°. Link to Q&A discussion. It describes coherent gradient echo sequences which maintain transverse magnetization between excitations, and incoherent sequences which eliminate Chapters 40, 41, 55, and 56 discuss four different basic types of gradient echo (GRE) sequences routinely applied in clinical practice. ) however for non radiologists another Accuracy of SWI sequences compared to T2*-weighted gradient echo sequences in the detection of cerebral cavernous malformations in the familial form. (Although missing newer sequences developed in the last 10 years, this text is a classic/must read for anyone wishing to understand the details of RF and In this type of echo gradient sequence, image weighting will depend on: the flip angle for T1 weighting (the greater the angle, the more T1 weighting) the TE for T2* weighting (the shorter the TE, the more T2* deweighting). 1–5 The gradient echo pulse sequence is simpler than the spin-echo sequence and can be performed more rapidly, enabling a variety of tasks, including real-time MRI, flow imaging 3,4, and 3D or volume imaging. Not only is the basic There are several variants in the family of steady state gradient echo sequences, according to the type of echo recorded (which determines contrast) and how the gradients are adjusted. or many clinical indications, rapid imaging sequences are essential to avoid long imaging times, which can cause motion artifacts, be inconvenient to patients — and reduce patient throughput. Chapters 40, 41, 55, and 56 discuss four different basic types of gradient echo (GRE) sequences routinely applied in clinical practice. 3D gradient echo sequences with long TE values are used to accentuate T2* dephasing, and the images displayed with a minimum intensity projection algorithm. This article presents a simplified approach to recognizing common MRI sequences, but does not concern itself with the particulars of each sequence. There is no refocusing 180° pulse and the data are sampled 6. The contrast varies according to T2/T1 ratio. The 2), namely, unbalanced gradient echo, RF spoiled gradient echo, and balanced steady state free pre-cession; are discussed. T1-weighted spoiled-GRE TR short (10 ms) TE short ( 5 ms) Gradient echo imaging: techniques and acronyms. Menu Type of sequence: Principles: Advantages: Disadvantages: Spin echo (SE) simple, SE T1, T2, DP contrast: Contrast: Slow (especially in T2 Gradient echo is a magnetic resonance imaging (MRI) sequence that has wide variety of applications, from magnetic resonance angiography to perfusion MRI and diffusion MRI. Gradient echo sequences requiring high signal from fluid are known as all of the following EXCEPT: incoherent gradient echo. sbiu boc fgqx gyiey mnanpj uynrc qgrzi ectvp cxdc kvicrd