A system, comprising: circuitry, configured to receive and process at least one signal tracking at least one physiological cycle of a subject; and a processor, configured to: receive the signal from the circuitry following the processing of the signal, obtain a set of ultrasound frames showing a portion of a heart of the subject, based on the signal, identify a subset of the frames responsively to the subset having been acquired at one or more predefined phases of the physiological cycle, compute respective image-quality scores for at least the subset of the frames, each of the scores quantifying an image quality with which one or more anatomical portions of interest are shown in a respective one of the frames, and based on the image-quality scores, select, for subsequent use, at least one frame from the subset of the frames if a respective image-quality score of the at least one frame exceeds a predefined image-quality-score threshold, wherein: the physiological cycle includes a respiratory cycle; or the processor is further configured to ascertain that a number of the image-quality scores passing a predefined image-quality-score threshold is less than a predefined frame-number threshold, and, in response to the ascertaining, output a warning; or the set includes between 60 and 120 frames. circuitry, configured to receive and process at least one signal tracking at least one physiological cycle of a subject; and a processor, configured to: receive the signal from the circuitry following the processing of the signal, obtain a set of ultrasound frames showing a portion of a heart of the subject, based on the signal, identify a subset of the frames responsively to the subset having been acquired at one or more predefined phases of the physiological cycle, compute respective image-quality scores for at least the subset of the frames, each of the scores quantifying an image quality with which one or more anatomical portions of interest are shown in a respective one of the frames, and based on the image-quality scores, select, for subsequent use, at least one frame from the subset of the frames if a respective image-quality score of the at least one frame exceeds a predefined image-quality-score threshold, wherein: the physiological cycle includes a respiratory cycle; or the processor is further configured to ascertain that a number of the image-quality scores passing a predefined image-quality-score threshold is less than a predefined frame-number threshold, and, in response to the ascertaining, output a warning; or the set includes between 60 and 120 frames. receive the signal from the circuitry following the processing of the signal, obtain a set of ultrasound frames showing a portion of a heart of the subject, based on the signal, identify a subset of the frames responsively to the subset having been acquired at one or more predefined phases of the physiological cycle, compute respective image-quality scores for at least the subset of the frames, each of the scores quantifying an image quality with which one or more anatomical portions of interest are shown in a respective one of the frames, and based on the image-quality scores, select, for subsequent use, at least one frame from the subset of the frames if a respective image-quality score of the at least one frame exceeds a predefined image-quality-score threshold, wherein: the physiological cycle includes a respiratory cycle; or the processor is further configured to ascertain that a number of the image-quality scores passing a predefined image-quality-score threshold is less than a predefined frame-number threshold, and, in response to the ascertaining, output a warning; or the set includes between 60 and 120 frames. the physiological cycle includes a respiratory cycle; or the processor is further configured to ascertain that a number of the image-quality scores passing a predefined image-quality-score threshold is less than a predefined frame-number threshold, and, in response to the ascertaining, output a warning; or the set includes between 60 and 120 frames.