Brudin L H, Rhodes C G, Valind S O, Buckingham P D, Jones T, Hughes J M
Medical Research Council, Royal Postgraduate Medical School, Hammersmith Hospital, London.
Thorax. 1992 Nov;47(11):914-21. doi: 10.1136/thx.47.11.914.
Positron emission tomography, performed with isotopes of very short half life, can be used to relate local lung tissue density to local ventilation and to the ventilation:perfusion ratio. This method has been used in 10 patients with severe chronic airflow obstruction and differing values for carbon monoxide transfer factor (TLCO) and transfer coefficient (KCO).
Ventilation (VA) and the ventilation:perfusion ratio (V/Q), lung density, and blood volume were measured regionally in a single transaxial section at mid-heart level with the patients in a supine position. Alveolar volume, extravascular tissue lung density, and perfusion (Q) were derived. Twenty five regions with abnormalities in the ventilation images were analysed.
Tissue density showed a negative correlation with the ratio V/Q (r = 0.55) and a positive correlation with Q (r = 0.59) and blood volume (r = 0.65). In four patients with a low carbon monoxide transfer factor (TLCO) and transfer coefficient (KCO) < 50% predicted many regions with low VA had low tissue density and normal or high V/Q. On the other hand, in four patients with TLCO and KCO > 50% predicted many regions with low VA had normal or high tissue density and low values of V/Q. The other two patients had patterns between these two extremes. Individual ratios between mean values of tissue density and V/Q had a positive correlation with KCO (% pred; r = 0.79).
These findings link structural differences with distinctive functional patterns; they reinforce the view that bronchial inflammation or oedema predominate in some patients with chronic airflow obstruction, whereas alveolar destruction is the major feature in others.
正电子发射断层扫描使用半衰期极短的同位素，可用于将局部肺组织密度与局部通气以及通气/灌注比联系起来。该方法已应用于10例严重慢性气流阻塞且一氧化碳转运因子（TLCO）和转运系数（KCO）值不同的患者。
患者仰卧位，在心脏中部水平的单个横断面区域测量通气（VA）、通气/灌注比（V/Q）、肺密度和血容量。推导得出肺泡容积、血管外组织肺密度和灌注（Q）。分析了通气图像中25个异常区域。
组织密度与V/Q比值呈负相关（r = 0.55），与Q呈正相关（r = 0.59），与血容量呈正相关（r = 0.65）。在4例一氧化碳转运因子（TLCO）低且转运系数（KCO）<预测值50%的患者中，许多VA低的区域组织密度低，V/Q正常或高。另一方面，在4例TLCO和KCO>预测值50%的患者中，许多VA低的区域组织密度正常或高，V/Q值低。另外2例患者的模式介于这两个极端之间。组织密度平均值与V/Q的个体比值与KCO（%预测值；r = 0.79）呈正相关。
这些发现将结构差异与独特的功能模式联系起来；它们强化了这样一种观点，即支气管炎症或水肿在一些慢性气流阻塞患者中占主导，而肺泡破坏在另一些患者中是主要特征。
