Two calculation methods to produce ventilation images from four-dimensional computed tomography (4DCT) acquired without added contrast have been reported. We reported a method to obtain ventilation images using deformable image registration (DIR) and the underlying CT density information. A second method performs the ventilation image calculation from the DIR result alone, using the Jacobian determinant of the deformation field to estimate the local volume changes resulting from ventilation. For each of these two approaches, there are variations on their implementation. In this study, two implementations of the Jacobian-based methodology are evaluated, as well as a single density change-based model for calculating the physiologic specific ventilation from 4DCT. In clinical practice, (99m)Tc-labeled aerosol single photon emission computed tomography (SPECT) is the standard method used to obtain ventilation images in patients. In this study, the distributions of ventilation obtained from the CT-based ventilation image calculation methods are compared with those obtained from the clinical standard SPECT ventilation imaging. Seven patients with 4DCT imaging and standard (99m)Tc-labeled aerosol SPECT/CT ventilation imaging obtained on the same day as part of a prospective validation study were selected. The results of this work demonstrate the equivalence of the Jacobian-based methodologies for quantifying the specific ventilation on a voxel scale. Additionally, we found that both Jacobian- and density-change-based methods correlate well with global measurements of the resting tidal volume. Finally, correlation with the clinical SPECT was assessed using the Dice similarity coefficient, which showed statistically higher (p-value < 10(-4)) correlation between density-change-based specific ventilation and the clinical reference than did either Jacobian-based implementation.

A four-dimensional deformable image registration (4D DIR) algorithm, referred to as 4D local trajectory modeling (4DLTM), is presented and applied to thoracic 4D computed tomography (4DCT) image sets. The theoretical framework on which this algorithm is built exploits the incremental continuity present in 4DCT component images to calculate a dense set of parameterized voxel trajectories through space as functions of time. The spatial accuracy of the 4DLTM algorithm is compared with an alternative registration approach in which component phase to phase (CPP) DIR is utilized to determine the full displacement between maximum inhale and exhale images. A publically available DIR reference database (http://www.dir-lab.com) is utilized for the spatial accuracy assessment. The database consists of ten 4DCT image sets and corresponding manually identified landmark points between the maximum phases. A subset of points are propagated through the expiratory 4DCT component images. Cubic polynomials were found to provide sufficient flexibility and spatial accuracy for describing the point trajectories through the expiratory phases. The resulting average spatial error between the maximum phases was 1.25 mm for the 4DLTM and 1.44 mm for the CPP. The 4DLTM method captures the long-range motion between 4DCT extremes with high spatial accuracy.

Percutaneous treatment of patent ductus arteriosus (PDA) in extreme premature infants is technically difficult, and therefore, often not consider as an alternative to surgery. The main objective of our work was to compare respiratory status prior and post ductal closure and morbi-mortality, in our series of preterm infants with percutaneous PDA closure versus surgical ligation in the same time-period. Retrospective review of all premature infants submitted to percutaneous and surgical PDA closure from January 2011 to December 2016. All the antenatal, perinatal, and postnatal characteristics were collected. The main outcome was the assessment of the pulmonary status before and after ductal closure using a pulmonary score. Secondary outcomes included moderate-severe disability in neurodevelopment, death before discharge, moderate-severe chronic lung disease, and morbidity at discharge. 25 patients with a mean weight of 1330 g (± 280) underwent percutaneous closure of PDA with ADO-II-AS, and a total of 53 underwent surgical ligation. 28/53 with similar gestational age, birth weight, and procedure weight to those in the percutaneous group, were selected to perform the comparative study. Ductal closure (percutaneous and surgical) resulted in improved respiratory status. However, percutaneous group achieved a fastest respiratory improvement, than surgical group. The surgical closure group associated higher morbidity among survivors (HIV, number of sepsis, need, and duration of inotropics post-interventionism). The incidence of recurrent laryngeal nerve palsy among the surgical group was 17%. Percutaneous closure of PDA in carefully selected low-weight preterm infants is a safe and reliable alternative to surgical ligation.

Purpose To quantify the post-radiotherapy 2-[18F]-fluoro-2-deoxyglucose (FDG) pulmonary uptake dose-response in lung cancer patients and determine its relationship with radiation pneumonitis symptoms. Methods and Materials The data from 24 patients treated for lung cancer with thoracic radiotherapy who received restaging PET/CT imaging between 4 and 12 weeks after radiotherapy completion were evaluated. Their radiation dose distribution was registered with the post-treatment restaging PET/CT. Using histogram analysis, the voxel average FDG-PET uptake versus radiation dose was obtained for each case and linear regression was performed. The resulting slope, the pulmonary metabolic radiation response (PMRR), was used to characterize the dose-response. The Common Toxicity Criteria version 3 was used to score clinical pulmonary toxicity symptoms. Receiver operating characteristic (ROC) curves were used to determine the level of FDG uptake v. dose, MLD, V5, V10, V20, and V30 that can best predict symptomatic and asymptomatic patients. Results The median time between radiotherapy completion and FDG-PET imaging was 59 days (range, 26–70 days). The median of the mean SUV from lung that received 0–5 Gy was 1.00 (range, 0.37–1.48), 5–10 Gy was 1.01 (range, 0.37–1.77), 10 –20 Gy was 1.04 (0.42–1.53), and > 20 Gy was 1.29 (range, 0.41–8.01). Using the dose range of 0 Gy to the maximum dose minus 10 Gy, hierarchical linear regression model of the radiation dose and normalized FDG uptake per case found an adequate fit with the linear model. Pneumonitis scores were: Grade 0 for 13, Grade 1 for 5, Grade 2 for 6, and Grade 3, 4 or 5 for none. Using a PMRR threshold of 0.017 yields an associated true positive rate of 0.67 and false positive rate of 0.15 with average error of 30%. A V5 threshold of 57.6 gives an associated true positive rate of 0.67 and false positive rate of 0.05 with a 20% average error. Conclusion The metabolic radiation pneumonitis dose response was evaluated from post-treatment FDG-PET/CT imaging. Statistical modeling found a linear relationship. The FDG uptake dose response and V5 correlated with symptomatic radiation pneumonitis.

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