Deep Learning Tool for Sarcopenia on CT: L1 Versus L3 Vertebral Level

Leesburg, VA, August 19, 2021According to ARRS’ American Journal of Roentgenology (AJR), use of the L1 vertebral level—typically included on both chest and abdominal CT examinations—rather than the L3 level expands the reach of opportunistic CT screening for sarcopenia.

“Automated CT-based measurements of muscle attenuation for myosteatosis at the L1 level compare favorably with previously-established L3 level measurements and clinical risk scores for predicting hip fractures and death,” wrote lead investigator Perry J. Pickhardt from the University of Wisconsin School of Medicine & Public Health in Madison. “Assessment for myopenia was less predictive of outcomes at both levels.”

Pickhardt and colleagues’ retrospective study included 9,223 patients (4,071 men, 5,152 women; mean age, 57 years) who underwent unenhanced low-dose abdominal CT. Muscle assessment for myosteatosis (mean attenuation) and myopenia (cross-sectional area) at the L1 and L3 levels was done via a previously validated fully-automated deep learning tool. Performance for predicting hip fractures and death was compared between L1 and L3 measures, then evaluated using FRAX score and Framingham risk score, respectively.

Among the 9,223 asymptomatic adults who underwent abdominal CT, muscle attenuation measurements at the L1 and L3 levels showed similar utility in predicting subsequent hip fracture and death. Meanwhile, muscle attenuation measurements at both levels showed comparable performance as established clinical risk scores.

The assessment of muscle attenuation (myosteatosis) performed better than the assessment of muscle area (myopenia) “likely due in part to the automated tool’s inclusion of intramuscular fat within the segmented areas,” the authors of this AJR article added.

An electronic supplement to this AJR article is available here.

Founded in 1900, the American Roentgen Ray Society (ARRS) is the first and oldest radiological society in North America, dedicated to the advancement of medicine through the profession of radiology and its allied sciences. An international forum for progress in medical imaging since the discovery of the x-ray, ARRS maintains its mission of improving health through a community committed to advancing knowledge and skills with an annual scientific meeting, monthly publication of the peer-reviewed American Journal of Roentgenology (AJR), quarterly issues of InPractice magazine, AJR Live Webinars and Podcasts, topical symposia, print and online educational materials, as well as awarding scholarships via The Roentgen Fund®.