SIDE LOBES AND GRATING LOBES ARTIFACTS IN ULTRASOUND IMAGING

Side lobes and grating lobes are both unwanted parts of the ultrasound beam emitted off axis that produce image artifacts due to error in po sitioning the returning echo, The purpose of this study was to reprodu ce artifacts associated with side lobes and grating lobes in vitro usi ng different transducer types and recognize these artifacts in vivo. A phantom, composed of a water bath, a metallic wire, and a wooden tong ue depressor, was imaged using a linear array, a curved linear array, a vector array, and a sector mechanical transducer, When imaging the m etallic wire in a transverse plane, an echogenic artifact was constant ly seen on each side of the wire, with a shape and intensity variable with the transducer type, The artifact was curvilinear and concave (li near and curved linear arrays), or curvilinear and convex (vector arra y and the mechanical transducer). When the tongue depressor was imaged in a longitudinal plane, the artifact was a straight line (linear arr ay), a curved convex line (curved array), a series of convex curviline ar echo (vector array) or a small convex curvilinear echo (mechanical transducer). In vivo situations similar to the phantom experiment were investigated using clinical patients, Artifacts produced in vitro wer e recognized in vivo when a highly reflective object (urinary bladder wall) was imaged adjacent to an anechoic region (urine), These artifac ts corresponded to the principle of secondary ultrasound lobes, and we re therefore interpreted as such.