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. Author manuscript; available in PMC: 2012 May 14.
Published in final edited form as: J Thorac Oncol. 2011 Jan;6(1):71–78. doi: 10.1097/JTO.0b013e3181f77b40

Figure 3. Mismatched V/Q defect.

Figure 3

There is a large mismatched defect with significantly reduced perfusion (Q) and normal V (arrow) in right middle and upper lobes, consistent with extrinsic compression of the pulmonary artery by the mass in hilum and mediastinum. If based on Q-SPECT only, this mismatched region would be considered as defect (“type B3” region) and potential for high dose radiation. Combined V/Q SPECT-CT can define and apply these regions as “type C region”, normal functioning “good” lung. The RT dose to such region should be minimized to decrease functional or clinically significant sequalae.