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Rady Children’s Launches No-Cost Z-Score Calculator

Updated ParameterZ Tool Expands Capabilities to Cardiac MRI

San Diego — March 15, 2023 – Rady Children’s Hospital–San Diego, the largest children’s hospital on the West Coast and one of the nation’s top pediatric healthcare systems, today announced the availability of ParameterZ by Rady Children’s Hospital, a no-cost standard deviation (z-score) calculator to help physicians throughout the U.S. and beyond understand the size of a patient’s cardiac anatomy in relation to what is perceived to be developmentally typical.

“We are fond of using z-scores in pediatric cardiology because they help us deal with the confounding effect of diverse and nuanced development of the human body. However, there is no one unifying z-score in clinical medicine,” said Dan Dyar, pediatric sonographer at Rady Children’s and creator of the original ParameterZ – a website built in 2006 to serve a similar purpose.

Developed with the support of the Helen and Will Webster Foundation 3D Innovations Lab and effort by research engineer Parham Gholami, the updated ParameterZ tool expands upon existing z-score calculators used for cardiac sonography (also known as ultrasound). Calculators for cardiac magnetic resonance imaging (MRI) studies are now included in the revised tool. The platform will eventually support the addition of even more imaging modalities as well as domains beyond cardiology, such as otolaryngology, neurology, and orthopedics.

Justin Ryan, PhD, director of the Webster Foundation 3D Innovations (3DI) Lab shared, “The use of z-scores is widespread throughout the field of pediatric medicine but existing tools often have many limitations. We sought to develop a comprehensive and modern calculator that offers physicians all over the world an accessible calculator at no cost. This is a simple yet often overlooked area as it can help avoid the risk of misclassification of patients.”

“We’re thrilled to share ParameterZ, the most extensive and user-friendly z-score calculator with physicians and practitioners worldwide,” said Sanjeet Hegde, MD, PhD, Director of Research at Rady Children’s Heart Institute. “What is often a cumbersome process is now streamlined into an accessible tool that allows doctors to make quick calculations so they can focus on what is truly at the heart of their work – providing excellent patient care.”

A selective preview of the site and application at a recent cardiac MRI conference led to great interest among physicians. Many are already looking forward to using this calculator in their day-to-day workflow given how important it is for patient care.

The tool is now available to all at no cost. ParameterZ by Rady Children’s Hospital will be updated periodically with new features and calculations over the coming months. Android and iOS mobile apps are currently in development.

For more information, please visit ParameterZ here.

MEDIA CONTACT: Ben Metcalf |