Anup Shah  
   Resident, Dept. of Urology  
   UW School of Medicine  

   Marla Paun,
   Engineer, CIMU  

   John Kucewicz,
   Engineer, CIMU  

   Oleg Sapozhnikov,
   Engineer, CIMU  

   Manjiri Dighe  
   Dept. of Urology  
   UW School of Medicine  

   Hunter McKay  
   Seattle Polyclinic  

   Mathew Sorensen  
   Resident, Dept. of Urology  
   UW School of Medicine  

   Mike Bailey,
   Engineer, CIMU  

   Larry Crum,
   Physicist, CIMU  


A Doppler mode in clinical diagnostic ultrasound detects motion, particularly blood flow, and displays the moving blood as red or blue on the imager's screen. For some unknown reason, when a stationary kidney stone is imaged in Doppler mode, the stone is displayed as a rainblow of colors, which makes the stone readily apparent. Something about the presence of the stone tricks the machine into displaying the color, which is an artifact because the color does not represent true motion.

Because twinkling is an artifact, its appearance can be intermittent and unreliable. The unreliability is exacerbated because of the variability of ultrasound imager proprietary technologies. We are focused on how to understand the artifact and make it into a useful tool to detect and treat kidney stones with lithotripsy.


We see at least three applications of the "twinkling artifact" to kidney stone treatment. First, stones are usually diagnosed with spiral CT imaging, which cannot be done in a doctor's office and exposes the patient to ionizing radiation. Our ultrasound technique would allow an immediate localization in the doctor's office and spare the patient the radiation exposure.

Second, most stone are treated by lithotripsy, where shock waves are sent into the patient's body to break stones. Most often X-ray fluoroscopy, which is generally not as good as spiral CT, is used to find the stone to target the treatement. These images are not always clear and sometimes the lithtripsy is done based on a best guess as to the stone's location. Twinkling could provide better targeting without the X-ray radiation.

Third, the stone moves as the patient breathes during lithotripsy treatment, which mean that about half the shock waves miss the stone and impact only kidney tissue. Lithotripsy has known side effects (i.e., tissue injury) and the fewer shock waves used the fewer side effects. Twinkling is a sensitive and real-time stone detector that could be used to ensure shock waves are only triggered when the stone is in the lithotripter's focus.

Right: Illustration of the "twinkling artifact." Shown in A and B are ultrasound images of a 2-mm stone inserted into an in vivo kidney. (A) scan in B-mode only; (B) color Doppler engaged. Note that the twinkling artifact shows a well defined stone (circled) while the B-mode image shows no obvious indication of a stone. (C) a stone is placed near a blood vessel and imaged in vivo; note that it is easy to distinguish between the stone exhibiting the twinkling artifact and regular blood flow. (D) photograph of the stone placed in the kidney.

The Twinkling Artifact project is the recipient of a commercialization grant from the UW Center for Commercialization. C4C supports UW's entrepreneurial researchers through comprehensive mentorship and access to technology-specific resources. Since 2005, C4C has provided more than $4.5 million in commercialization gap funds to over 100 UW projects and start-up companies. More >>