Dr. Vasquez typed her report: Findings: Cardiomegaly. Prominent interstitial markings with bilateral Kerley B lines in the lower lung zones, consistent with pulmonary venous hypertension and early interstitial edema. She picked up the phone to call the emergency department.

Kerley B lines.

She glanced back at the image. The lines were quiet, delicate, almost easy to miss. But to her, they screamed as loudly as any siren.