Functional lung mapping from Ga68-ventilation/perfusion (V/Q) PET/CT, which has been shown to correlate with pulmonary function tests (PFTs), may be beneficial in a number of clinical applications where sparing regions of high lung function is of interest. Regions of clumping in the proximal airways in patients with airways disease can result in areas of focal intense activity and artefact in ventilation imaging. These artefacts may even shine through to subsequent perfusion images and create a challenge for quantitative analysis of PET imaging. We aimed to develop an automated algorithm that interprets the uptake histogram of PET images to calculate a peak uptake value more representative of the global lung volume. Sixty-six patients recruited from a prospective clinical trial underwent both V/Q PET/CT imaging and PFT analysis before treatment. PET images were normalised using an iterative histogram analysis technique to account for tracer hotspots prior to the threshold-based delineation of varying values. Pearson’s correlation between fractional lung function and PFT score was calculated for ventilation, perfusion, and matched imaging volumes at varying threshold values. For all functional imaging thresholds, only FEV1/FVC PFT yielded reasonable correlations to image-based functional volume. For ventilation, a range of 10–30% of adapted peak uptake value provided a reasonable threshold to define a volume that correlated with FEV1/FVC (r = 0.54–0.61). For perfusion imaging, a similar correlation was observed (r = 0.51–0.56) in the range of 20–60% adapted peak threshold. Matched volumes were closely linked to ventilation with a threshold range of 15–35% yielding a similar correlation (r = 0.55–0.58). Histogram normalisation may be implemented to determine the presence of tracer clumping hotspots in Ga-68 V/Q PET imaging allowing for automated delineation of functional lung and standardisation of functional volume reporting.

中文翻译：

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使用迭代直方图分析通过⁶⁸ Ga换气/灌注PET / CT自动评估功能性肺部成像

通过Ga68换气/灌注（V / Q）PET / CT进行的功能性肺定位已显示与肺功能测试（PFT）相关，在许多临床应用中，肺功能高的稀疏区域可能是有益的，这可能是有益的兴趣。气道疾病患者近端气道的结块区域可导致局部局部剧烈活动和通气成像伪像。这些伪像甚至可以照亮到后续的灌注图像，并为PET成像的定量分析带来挑战。我们旨在开发一种自动算法，该算法解释PET图像的摄取直方图，以计算出更能代表全球肺活量的峰值摄取值。从前瞻性临床试验中招募的66例患者在治疗前均接受了V / Q PET / CT成像和PFT分析。使用迭代直方图分析技术对PET图像进行归一化，以在基于阈值描绘变化值之前说明示踪剂热点。计算通气，灌注和在不同阈值下匹配的成像体积之间的肺功能分数和PFT评分之间的Pearson相关性。对于所有功能成像阈值，只有FEV1 / FVC PFT与基于图像的功能量产生合理的相关性。对于通气，适应峰吸收值的10–30％的范围提供了合理的阈值，以定义与FEV1 / FVC相关的体积（r = 0.54–0.61）。对于灌注成像，在适应性峰值阈值的20-60％范围内观察到相似的相关性（r = 0.51-0.56）。匹配的体积与通风密切相关，阈值范围为15–35％，产生相似的相关性（r = 0.55–0.58）。可以实施直方图归一化来确定Ga-68 V / Q PET成像中示踪剂聚集热点的存在，从而实现功能肺的自动描绘和功能量报告的标准化。