Question 2832
{"accessible":false,"alternatives":[{"id":13820,"text":"better signal to noise ratio"},{"id":13821,"text":"improved axial resolution"},{"id":13822,"text":"improved contrast"},{"id":13823,"text":"improved lateral resolution"},{"id":13824,"text":"reduction in side lobe artifact"}],"archived":false,"correctAlternativeId":13821,"explanation":"\u003cp\u003eHarmonic imaging usually has reduced axial resolution compared to non-harmonic B-mode imaging. This is because the resonance frequency generated in harmonic imaging needs to have a narrow bandwidth, to ensure harmonic frequencies - which are integer multiples of the resonance frequency - are easier to detect. A narrow bandwidth is created with a longer spatial pulse length pulse. Lengthening of spatial pulse length reduces axial resolution.\u003c/p\u003e\u003cp\u003eBecause only the tissue harmonic frequencies are used to generate the image there is an improvement in signal to noise ratio and subsequently contrast. Lateral resolution improves because only the most intense region in the beam generates harmonic frequencies (this region is narrower than the ultrasound beam itself). Side lobe artifact is reduced because the side lobes have insufficient intensity to produce tissue harmonics. \u003c/p\u003e","id":2832,"imageUrl":null,"imageAttribution":null,"imageAttributionCaseInfo":null,"firstQuestionPath":"/questions/2832","nextQuestionPath":"/articles/ultrasound-artifacts-3/questions/2824","relatedArticles":[{"id":25238,"title":"Harmonic imaging","link":"/articles/harmonic-imaging?lang=us"},{"id":47372,"title":"Side lobe artifact","link":"/articles/side-lobe-artifact-2?lang=us"},{"id":66176,"title":"Axial resolution (ultrasound)","link":"/articles/axial-resolution-ultrasound?lang=us"},{"id":66177,"title":"Lateral resolution (ultrasound)","link":"/articles/lateral-resolution-ultrasound?lang=us"},{"id":84376,"title":"Spatial pulse length (ultrasound)","link":"/articles/spatial-pulse-length-ultrasound?lang=us"}],"alsoUsedIn":[{"id":1620,"kind":"RestrictedPage","title":"Page 1620 (in no courses)","link":"https://radiopaedia.org/admin/restricted_pages/1620"},{"id":1984,"kind":"Course","title":"Imaging Physics: Ultrasound Peer Review - page 1984","link":"https://radiopaedia.org/courses/imaging-physics-ultrasound-peer-review/pages/1984"},{"id":1984,"kind":"Course","title":"Imaging Physics: Ultrasound - page 1984","link":"https://radiopaedia.org/courses/imaging-physics-ultrasound/pages/1984"}],"stem":"\u003cp\u003eWhich of the following is not an advantage of harmonic ultrasound imaging?\u003c/p\u003e","menuLinks":[{"text":"Report problem with question","url":"https://docs.google.com/forms/d/e/1FAIpQLSfO3soWYhOjJ7yErSysyCe5V4A1CqW7WK3rDA7MtAkecMGqNw/viewform?entry.1624461248\u0026entry.553583435=https://radiopaedia.org/questions/2832"}],"attemptsPercentages":[{"alternativeId":"13823","percentage":13},{"alternativeId":"13822","percentage":7},{"alternativeId":"13820","percentage":5},{"alternativeId":"13824","percentage":13},{"alternativeId":"13821","percentage":61}],"promptToLogin":false,"questionManager":false,"articleId":"ultrasound-artifacts"}