The resistive index (RI),

Ultrasound (US) is an extremely useful diagnostic imaging modality because of its real-time capability, noninvasiveness, portability, and relatively low cost. It carries none of the potential risks of ionizing radiation exposure or intravenous contrast administration. For these reasons, numerous medical specialties now rely on US not only for diagnosis and guidance for procedures, but also as an extension of the physical examination. In addition, many medical school educators recognize the usefulness of this technique as an aid to teaching anatomy, physiology, pathology, and physical diagnosis. Radiologists are especially interested in teaching medical students the appropriate use of US in clinical practice. Educators who recognize the power of this tool have sought to incorporate it into the medical school curriculum. The basic question that educators should ask themselves is: "What should a student graduating from medical school know about US?" To aid them in answering this question, US specialists from the Society of Radiologists in Ultrasound and the Alliance of Medical School Educators in Radiology have collaborated in the design of a US curriculum for medical students. The implementation of such a curriculum will vary from institution to institution, depending on the resources of the medical school and space in the overall curriculum. Two different examples of how US can be incorporated vertically or horizontally into a curriculum are described, along with an explanation as to how this curriculum satisfies the Accreditation Council for Graduate Medical Education competencies, modified for the education of our future physicians.

It has recently been suggested that the resistive index (RI) in native kidneys of healthy children is age dependent; however, this relationship has not been completely defined or explained. In 110 kidneys in 71 healthy children aged newborn to 11 years, RIs were determined from peripheral sites (presumed to be arcuate, cortical, or distal interlobar arteries). The authors found the normal renal RI (the mean RI in each kidney) to be age dependent. The renal RI in children is commonly elevated above the upper normal limit in adults (0.70) in the 1st year of life, and the overall trend shows a decrease with age. From 4 years on, the likelihood is low (2% probability) that the RI is above 0.70. Variability of the renal RI from individual to individual was most marked in the first 6 months of life, with 51% (19 of 37) of these kidneys having an RI that would be considered abnormal by adult standards. It is concluded that the normal renal RI is age dependent, with an overall decreasing trend with increasing age. This age dependency of the renal RI and, hence, of the renal vascular resistance might be dependent on levels of active renin, as the maturational profile of the renal RI more closely parallels that of active renin than those of other renal functional parameters.

Purpose:To retrospectively correlate sonographic color Doppler twinkling artifact within the kidneys with unenhanced computed tomography (CT ) in the detection of nephrolithiasis. Materials and Methods:Institutional review board approval was obtained for this retrospective HIPAA-complaint investigation, and the informed consent requirement was waived. Sonographic imaging reports describing the presence of renal twinkling artifact between January 2008 and September 2009 were identifi ed. Subjects who did not undergo unenhanced abdominal CT within 2 weeks after sonography were excluded. Ultrasound examinations were reviewed by three radiologists working together, and presence, number, location, and size of renal twinkling artifacts were documented by consensus opinion. Sonographic fi ndings were correlated with unenhanced CT (5-mm section width, no overlap) for nephrolithiasis and other causes of twinkling artifact. The number, location, and size of renal calculi at CT were documented. Results:The presence of sonographic renal twinkling artifact, in general, had a 78% (95% confi dence interval: 0.66, 0.90) positive predictive value for nephrolithiasis anywhere in the kidneys at CT. The true-positive rate of twinkling artifact for confi rmed calculi at CT was 49% (73 of 148 twinkling foci), while the false-positive rate was 51% (75 of 148 twinkling foci). The overall sensitivity of twinkling artifact for the detection of specifi c individual renal calculi observed at CT was 55% (95% confi dence interval: 0.47, 0.64). Conclusion:While renal twinkling artifact is commonly associated with nephrolithiasis, this fi nding is relatively insensitive in routine clinical practice and has a high false-positive rate when 5-mm unenhanced CT images are used as the reference standard.q RSNA, 2011Supplemental material: http://radiology.rsna.org/lookup /suppl

No abstract