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Scholarly Works (2 results)

  • Thesis
  • Peer Reviewed
UC San Diego Electronic Theses and Dissertations (2023)

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) is a disease where patients have unresolved clots in their pulmonary vasculature. Patients can be successfully treated by Pulmonary Thromboendarterectomy (PTE) when the pulmonary hemodynamic impairment is due to surgically accessible CTEPH disease burden (fibrotic clot and resulting downstream perfusion deficits). Unfortunately, up to 10 - 50% of patients who undergo the surgery will have residual pulmonary hypertension, which carries higher complication and mortality rates. Residual pulmonary hypertension is thought to occur in patients with either microvascular remodeling, mixed pulmonary hypertension types, or chronic clot too distal in the vasculature for complete surgical removal. As such, key preoperative questions to identify patients likely to benefit from PTE are (1) the extent to which their vascular obstructions and associated perfusion deficits are the drivers of hemodynamic impairment and (2) whether the obstructions are surgically accessible for removal (aka located in lobar to sub- segmental vessels).Both of the above questions are currently assessed by expert visual interpretation of imaging studies alongside hemodynamic measures prior to PTE surgery. Unfortunately, there are currently no quantitative tools to aid these evaluations. As a result, the impact of specific lesions, the total disease burden, and the amount of surgically-accessible disease on PTE risk-benefit determination is unclear. Thus, there is a need to develop tools to systematically and objectively assess CTEPH patients being evaluated for PTE surgery. This work aims to develop quantitative imaging measures to assess CTEPH characteristics important for surgical planning. To accomplish this, first we focus on the ability of Dual Energy CT Pulmonary Angiograms to evaluate agreement between CTEPH disease burden and hemodynamic severity. Next, we evaluate the ability of Machine Learning Analysis of Ventilation Perfusion Images predict surgical disease level, an indication of clot location with important accessibility implications.

    Cover page: Development of Quantitative Phenotyping Tools to Improve Pulmonary Thromboendarterectomy Risk-Benefit Assessment in Patients with Chronic Thromboembolic Pulmonary Hypertension
    • Article
    • Peer Reviewed
    UC San Diego Previously Published Works (2023)

    Purpose

    To assess if a novel automated method to spatially delineate and quantify the extent of hypoperfusion on multienergy CT angiograms can aid the evaluation of chronic thromboembolic pulmonary hypertension (CTEPH) disease severity.

    Materials and methods

    Multienergy CT angiograms obtained between January 2018 and December 2020 in 51 patients with CTEPH (mean age, 47 years ± 17 [SD]; 27 women) were retrospectively compared with those in 110 controls with no imaging findings suggestive of pulmonary vascular abnormalities (mean age, 51 years ± 16; 81 women). Parenchymal iodine values were automatically isolated using deep learning lobar lung segmentations. Low iodine concentration was used to delineate areas of hypoperfusion and calculate hypoperfused lung volume (HLV). Receiver operating characteristic curves, correlations with preoperative and postoperative changes in invasive hemodynamics, and comparison with visual assessment of lobar hypoperfusion by two expert readers were evaluated.

    Results

    Global HLV correctly separated patients with CTEPH from controls (area under the receiver operating characteristic curve = 0.84; 10% HLV cutoff: 90% sensitivity, 72% accuracy, and 64% specificity) and correlated moderately with hemodynamic severity at time of imaging (pulmonary vascular resistance [PVR], ρ = 0.67; P < .001) and change after surgical treatment (∆PVR, ρ = -0.61; P < .001). In patients surgically classified as having segmental disease, global HLV correlated with preoperative PVR (ρ = 0.81) and postoperative ∆PVR (ρ = -0.70). Lobar HLV correlated moderately with expert reader lobar assessment (ρHLV = 0.71 for reader 1; ρHLV = 0.67 for reader 2).

    Conclusion

    Automated quantification of hypoperfused areas in patients with CTEPH can be performed from clinical multienergy CT examinations and may aid clinical evaluation, particularly in patients with segmental-level disease.Keywords: CT-Spectral Imaging (Multienergy), Pulmonary, Pulmonary Arteries, Embolism/Thrombosis, Chronic Thromboembolic Pulmonary Hypertension, Multienergy CT, Hypoperfusion© RSNA, 2023.
      Cover page: Mapping the Spatial Extent of Hypoperfusion in Chronic Thromboembolic Pulmonary Hypertension Using Multienergy CT.
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