Vq near segmental defect in superior of left lower lobe. greater then75%defect on perfusion, no evidence of defect on ventilation. few tiny subseqment?

Pulmonary embolus?: What you are describing is a lung scan. The ratio of ventilation to perfusion is important. With a pulmonary embolus or blood clot there is decreased perfusion when compared to ventilation. With lung disease ventilation is effected more than perfusion. The defect in perfusion suggests a pulmonary embolus and the other tiny sub segmental lesions also are consistent with this.