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Introduction

  1. Top of page
  2. Introduction
  3. Methods
  4. Results
  5. Conclusions

Prediction of pulmonary hypoplasia remains difficult. At autopsy, pathologists use the lung weight/body weight ratio to diagnose pulmonary hypoplasia. Estimating lung volumes in utero could aid management when pulmonary hypoplasia is suspected. We measured fetal lung volumes on post mortem MRI. By comparing these volumes to organ weights at autopsy, we estimated fetal lung densities. This may allow prenatal calculation of lung weights in future.

Methods

  1. Top of page
  2. Introduction
  3. Methods
  4. Results
  5. Conclusions

21 fetuses underwent postmortem MRI at 1.5T prior to conventional autopsy with parental consent. Fetal weights ranged from 113–3270 g, with gestational ages of 17–40 weeks. T2-weighted sequences were used. Conventional autopsies were performed to RCPath guidelines. Lung volumes were independently estimated by two researchers using the ANALYZE (BIR, Mayo Foundation) software package's stereology tool. Organ volumes for each observer were compared to autopsy organ weights, and the reciprocal of the gradients and R2 values were calculated. Inter-observer agreement was assessed using Bland-Altman analysis.

Results

  1. Top of page
  2. Introduction
  3. Methods
  4. Results
  5. Conclusions

There was high linear correlation between estimated lung volume and actual lung weights (R2 > 0.98 for both observers). The reciprocal of the gradient gave an average lung density of 1.15 g/cm3 which corresponds closely to the density of non-aerated adult lung (1.04–1.09). Bland-Altman analysis demonstrated good inter-observer agreement, which appeared to improve with increasing organ size.

Conclusions

  1. Top of page
  2. Introduction
  3. Methods
  4. Results
  5. Conclusions

Ex utero fetal lung volume measurements are highly correlated to lung weight at autopsy, with a calculated density that corresponds well to published figures. The technique has low inter-observer variability and provides non-invasive information about fetal lung development when conventional autopsy is declined. It may also prove of value in the prenatal assessment of lung development.