Ultrasound Resolution PDF

Comparison of Lateral & Axial Resolution in Ultrasound Aspect Axial Resolution Lateral Resolution Axial Resolution Side by side; Front to back; Orientation Perpendicular to Parallel to b...

Comparison of Lateral & Axial Resolution in Ultrasound Aspect Axial Resolution Lateral Resolution Axial Resolution Side by side; Front to back; Orientation Perpendicular to Parallel to beam beam LATA (Lateral, LARD (Linear, Axial, Azimuthal, Mnemonic Range, Depth) Transverse, Angular) Lateral Resolution Determined by Pulse length Beam width Using a shorter Beam is narrowest, Optimal When pulse with high often at the focal frequency point Consistent Varies with depth, throughout, does Variability best at the focal not change with zone depth Resolution: A. Related to Transducer 3. Slice Thickness (Elevational Resolution) Elevational resolution, also known as slice thickness, complements axial and lateral resolution, forming the third dimension of detail resolution in ultrasound imaging. It describes the width of the imaging plane, which is the dimension of the beam that extends perpendicular to the image plane. Inadequate elevational resolution can obscure the depiction of small, cystic structures. It is influenced by the height of the transducer's element, which is generally the least resolved axis compared to axial and lateral dimensions. Poor elevational resolution can lead to section thickness artifacts, commonly known as partial-volume artifacts, which can result in the erroneous representation of anechoic structures, such as cysts, appearing filled. Resolution :B. Related to instrument 1. Temporal resolution refers to the capacity of an ultrasound system to depict motion and changes in anatomy over time. This is crucial for dynamic studies such as echocardiography. 1.Temporal resolution is directly affected by the frame rate, which is the frequency at which consecutive images are captured and displayed. 2.An increased frame rate enhances the ability to visualize rapid movements, resulting in better temporal resolution. 3.Temporal resolution is measured in Hertz (Hz), which represents the number of frames captured per second. Determining Factors for Frame Rate: Speed of Sound: Typically 1540 m/s in soft tissue Imaging Depth: The deeper the imaging, the lower the achievable frame rate due to the time needed for sound to travel. Strategies to Improve Frame Rate in Ultrasound Enhancing the frame rate can lead to better temporal resolution, which is especially important for capturing dynamic processes. Here are common methods to increase frame rate: 1.Narrow the Imaging Sector: Reduces the scan time for each frame, leading to a faster frame rate. 2.Decrease Imaging Depth: Lowers the Pulse Repetition Period (PRP), enabling quicker frame cycles. 3.Reduce Line Density: Requires fewer lines to be scanned per frame, which can speed up processing at the expense of spatial resolution. 4.Disable Multifocal Technology: Limits the number of pulses per line, potentially increasing frame rate Frame Rate X Line Density= PRF Line Density in Ultrasound Imaging High Line Density is achieved with Line density refers to the number closely packed lines, Improves of scan lines per unit area in an image accuracy and detail (spatial ultrasound image. It is determined resolution); however, a higher line by the spacing between each density can reduce temporal beam. resolution, as the system requires more time to acquire data.  Resolution :B. Related to instrument int i 2. Contrast resolution is the ultrasound system's capacity to differentiate between tissues with varying echogenic properties, such as the liver and spleen. Contrast resolution is dependent on the bit depth - the number of bits per pixel stored in the image memory. Increasing the number of bits per pixel allows for more shades of gray, enhancing contrast resolution.