Rationale Effective prognostic biomarkers in Non-specific Interstitial Pneumonitis (NSIP) are limited. Objective To investigate the potential of [18F]FDG PET/CT to predict mortality in NSIP and to assess its relationship with physiological indices and the Interstitial Lung Disease – Gender-Age-Physiology (ILD-GAP) score. Methods Ninety-six patients with a multidisciplinary team-confirmed diagnosis of NSIP (40 male, 56 female; mean age 59.8 ± 9.8 years) underwent baseline [18F]FDG PET/CT and 83 patients completed full pulmonary function testing. Pulmonary uptake of [18F]FDG was quantified using region-of-interest analysis as the maximum uptake in diseased lung (SUVmax) and the background uptake in visually normal lung (SUVmin). A target-to-background (TBR) ratio was calculated as SUVmax /SUVmin. Kaplan-Meier survival analysis examined associations between the [18F]FDG PET/CT metrics, the pulmonary function tests and ILD-GAP scores. Stepwise forward Wald multivariable Cox regression assessed independence of the significant [18F]FDG PET/CT parameters from the ILD-GAP index. The modified ILD-GAP (mGAP) models were generated by incorporating the [18F]FDG PET/CT data into the ILD-GAP index. Results 65 patients died during a mean follow up of 83.2 ± 48.2 months. Mean ± SD SUVmax, SUVmin and TBR were 3.2 ± 1.2, 0.6 ± 0.3 and 6.0 ± 2.4, respectively. Mortality was associated with higher SUVmax (median cutoff ≥ 2.9, p = 0.038) and higher SUVmin (optimised cutoff ≥ 0.675, p < 0.001), whereas TBR was not prognostic (p = 0.48). Multivariable Cox regression confirmed median SUVmax as independent of ILD-GAP index (p = 0.031), although optimised SUVmin was not independent. Incorporating either parameter into a modified ILD-GAP model improved survival stratification compared with ILD-GAP index alone (p < 0.01, log-rank test). Conclusion High pulmonary [18F]FDG PET/CT uptake predicts increased mortality in NSIP. Median SUVmax is an independent predictor of mortality and adding [18F]FDG PET/CT parameters to the ILD-GAP index enhances prognostic discrimination. These findings support a disease-specific interpretation of [18F]FDG PET/CT metrics in ILD, where SUVmax and SUVmin are dominant prognostic markers in diffuse NSIP.

Pulmonary [¹⁸F]FDG uptake demonstrates phenotypic PET behaviour in non-specific interstitial pneumonitis and refines risk stratification

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2026年7月25日

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Hannah Torlot,
Balaji Ganeshan,
Thida Win,
Helen Garthwaite,
Luke R. Hoy,
Darren Walls,
Raymond Endozo,
Robert I. Shortman,
Francesco Fraioli,
Nicholas J. Screaton,
Joanna C. Porter,
Ashley M. Groves

摘要

Rationale

Effective prognostic biomarkers in Non-specific Interstitial Pneumonitis (NSIP) are limited.

Objective

To investigate the potential of [¹⁸F]FDG PET/CT to predict mortality in NSIP and to assess its relationship with physiological indices and the Interstitial Lung Disease – Gender-Age-Physiology (ILD-GAP) score.

Methods

Ninety-six patients with a multidisciplinary team-confirmed diagnosis of NSIP (40 male, 56 female; mean age 59.8 ± 9.8 years) underwent baseline [¹⁸F]FDG PET/CT and 83 patients completed full pulmonary function testing. Pulmonary uptake of [¹⁸F]FDG was quantified using region-of-interest analysis as the maximum uptake in diseased lung (SUV_max) and the background uptake in visually normal lung (SUV_min). A target-to-background (TBR) ratio was calculated as SUV_max /SUV_min. Kaplan-Meier survival analysis examined associations between the [¹⁸F]FDG PET/CT metrics, the pulmonary function tests and ILD-GAP scores. Stepwise forward Wald multivariable Cox regression assessed independence of the significant [¹⁸F]FDG PET/CT parameters from the ILD-GAP index. The modified ILD-GAP (mGAP) models were generated by incorporating the [¹⁸F]FDG PET/CT data into the ILD-GAP index.

Results

65 patients died during a mean follow up of 83.2 ± 48.2 months. Mean ± SD SUV_max, SUV_min and TBR were 3.2 ± 1.2, 0.6 ± 0.3 and 6.0 ± 2.4, respectively. Mortality was associated with higher SUV_max (median cutoff ≥ 2.9, p = 0.038) and higher SUV_min (optimised cutoff ≥ 0.675, p < 0.001), whereas TBR was not prognostic (p = 0.48). Multivariable Cox regression confirmed median SUV_max as independent of ILD-GAP index (p = 0.031), although optimised SUV_min was not independent. Incorporating either parameter into a modified ILD-GAP model improved survival stratification compared with ILD-GAP index alone (p < 0.01, log-rank test).

Conclusion

High pulmonary [¹⁸F]FDG PET/CT uptake predicts increased mortality in NSIP. Median SUV_max is an independent predictor of mortality and adding [¹⁸F]FDG PET/CT parameters to the ILD-GAP index enhances prognostic discrimination. These findings support a disease-specific interpretation of [¹⁸F]FDG PET/CT metrics in ILD, where SUV_max and SUV_min are dominant prognostic markers in diffuse NSIP.

Pulmonary [18F]FDG uptake demonstrates phenotypic PET behaviour in non-specific interstitial pneumonitis and refines risk stratification

摘要

Pulmonary [¹⁸F]FDG uptake demonstrates phenotypic PET behaviour in non-specific interstitial pneumonitis and refines risk stratification