A reference equation for lung volume on computed tomography in Japanese middle-aged and elderly adults

BACKGROUND

Effective use of lung volume data measured on computed tomography (CT) requires reference values for specific populations. This study examined whether an equation previously generated for multiple ethnic groups in the United States, including Asians predominantly composed of Chinese people, in the Multi-Ethnic Study of Atherosclerosis (MESA) could be used for Japanese people and, if necessary, to optimize this equation. Moreover, the equation was used to characterize patients with chronic obstructive pulmonary disease (COPD) and lung hyperexpansion.

METHODS

This study included a lung cancer screening CT cohort of asymptomatic never smokers aged ≥40 years from two institutions (n = 364 and 419) to validate and optimize the MESA equation and a COPD cohort (n = 199) to test its applicability.

RESULTS

In all asymptomatic never smokers, the variance explained by the predicted values (R2) based on the original MESA equation was 0.60. The original equation was optimized to minimize the root mean squared error (RMSE) by adjusting the scaling factor but not the age, sex, height, or body mass index terms of the equation. The RMSE changed from 714 ml in the original equation to 637 ml in the optimized equation. In the COPD cohort, lung hyperexpansion, defined based on the 95th percentile of the ratio of measured lung volume to predicted lung volume in never smokers (122 %), was observed in 60 (30 %) patients and was associated with centrilobular emphysema and air trapping on inspiratory/expiratory CT.

CONCLUSIONS

The MESA equation was optimized for Japanese middle-aged and elderly adults.

Congenital diaphragmatic hernia sacs: prenatal imaging and associated postnatal outcomes

BACKGROUND

The presence of a hernia sac in congenital diaphragmatic hernia (CDH) has been reported to be associated with higher lung volumes and better postnatal outcomes.

OBJECTIVE

To compare prenatal imaging (ultrasound and MRI) prognostic measurements and postnatal outcomes of CDH with and without hernia sac.

MATERIALS AND METHODS

We performed database searches from January 2008 to March 2017 for surgically proven cases of CDH with and without hernia sac. All children had a detailed ultrasound (US) examination and most had an MRI examination. We reviewed the medical records of children enrolled in our Pulmonary Hypoplasia Program.

RESULTS

Of 200 cases of unilateral CDH, 46 (23%) had hernia sacs. Cases of CDH with hernia sac had a higher mean lung-to-head ratio (LHR; 1.61 vs. 1.17; P<0.01), a higher mean observed/expected LHR (0.49 vs. 0.37; P<0.01), and on MRI a higher mean observed/expected total lung volume (0.53 vs. 0.41; P<0.01). Based on a smooth interface between lung and herniated contents, hernia sac or eventration was prospectively questioned by US and MRI in 45.7% and 38.6% of cases, respectively. Postnatally, hernia sac is associated with shorter median periods of admission to the neonatal intensive care unit (45.0 days vs. 61.5 days, P=0.03); mechanical ventilation (15.5 days vs. 23.5 days, P=0.04); extracorporeal membrane oxygenation (251 h vs. 434 h, P=0.04); decreased rates of patch repair (39.0% vs. 69.2%, P<0.01); and pulmonary hypertension (56.1% vs. 75.4%, P=0.03).

CONCLUSION

Hernia sac is associated with statistically higher prenatal prognostic measurements and improved postnatal outcomes. Recognition of a sharp interface between lung and herniated contents may allow for improved prenatal diagnosis; however, delivery and management should still occur at experienced quaternary neonatal centers.