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TH‐E‐217BCD‐11: Validation of 4D Computed Tomography (4D‐CT) to Evaluate Fractional Regional Ventilation against the Clinical Gold‐Standard Scintigraphy V/Q
Author(s) -
Diwanji T,
Feigenberg S,
D'Souza W,
Mistry N
Publication year - 2012
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4736385
Subject(s) - nuclear medicine , scintigraphy , gold standard (test) , medicine , single photon emission computed tomography , ventilation (architecture) , radiation treatment planning , medical imaging , lung cancer , mathematics , radiology , radiation therapy , physics , thermodynamics
Purpose : To validate the use of 4D‐Computed Tomography (4D‐CT) for pre‐treatment evaluation of fractional regional ventilation in patients with lung cancer by benchmarking its performance against scintigraphy V/Q imaging, the current gold‐standard. The second aim is to further corroborate the results of 4D‐CT estimation of lung aeration against the results of Pulmonary Function Testing. Methods : Scintigraphy V/Q and 4D‐CT studies were acquired in four lung cancer patients prior to treatment with radiation therapy. PFTs were acquired in 3 out of the 4 patients. 4D‐CT images were used to create 3D fractional regional ventilation maps by applying a ‘mass correction’ and subtracting the spatially matched end‐exhale and end‐inhale images. Ventilation maps were then collapsed in the anterior‐posterior dimension to create a coronal 2D projection image consistent with the scintigraphy V/Q images. The left and right lung fields were isolated on the projection image and divided into 3 sections of equal height. Summation of the signal intensity in each of the sections was carried out on the maps analogous to the analysis performed on V/Q scans and statistically compared using the Kendall's tau rank correlation. Results : The non‐parametric Kendall's tau estimate ranged between 0.87–0.95 for N=4, with corresponding p‐values ranging between 0.005–0.0002. Mean functional residual capacities (FRC) from the PFTs (N=3) versus calculated FRCs was 2.7 +/− 0.6 L and 2.4 +/− 0.7 L, and the null hypothesis could not be rejected (p = 0.61). The mean fractional regional ventilation versus the ratio of tidal‐volume/FRC was 0.24 +/– 0.11 and 0.22 +/– 0.08, and the null hypothesis could not be rejected (p=0.73). Conclusions : There was a strong correlation between 4D‐CT and scintigraphy V/Q. The similarity between the calculated and measured FRCs further validates the utility of 4D‐CT and supports its use in evaluating lung ventilation in patients with pulmonary neoplasms.