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Lesion to Hemithorax Ratio Predicts Onset of Respiratory Symptoms and Requirement for Early Surgery In Congenital Lung Malformations

Saturday, October 20, 2012
Napoleon Ballroom (Hilton Riverside)
David Keene1, Patrick Green2, Eniola Folaranmi1, George Rakoczy1, Abdu Shabani1, James Bruce1 and Gill Humphrey1, (1)Paediatric Surgery, Royal Manchester Children's Hospital, Manchester, United Kingdom, (2)Manchester Medical School, University of Manchester, Manchester, United Kingdom

Purpose:

To determine whether lesion to hemithorax (LTH) ratio on cross-sectional imaging, can predict the onset of symptoms and requirement for early surgery in congenital lung malformations (CLMs).

Methods:

A retrospective review of all infants diagnosed with CLMs between 2000 and 2010 was performed. Infants included were those with a diagnosis of CLM confirmed on postnatal CT scan or histology report. Data were collected from antenatal and postnatal case-notes. Age, diagnosis, respiratory symptoms and lesion dimensions were recorded. Patients were classified as symptomatic if they developed grunting, recession, cyanosis, tachypnoea or desaturations.

Lesion and hemithorax volumes were estimated using the formula for a prolate ellipsoid:

Volume (mls) = depth x width x height (cm) x 0.52

Lesion to hemithorax (LTH) ratio was devised to estimate the CLM size relative to patient size. LTH ratio was calculated using the formula:

LTH ratio (%) = (Lesion volume Hemithorax volume (mls)) x 100

Kendall rank correlation was calculated using Stats Direct 2.7.8 (Stats Direct Ltd, Altrincham, Cheshire, UK). Data are expressed as medians (interquartile range).

Results:

CT scans were performed in 94 of the 97 patients. Median age at CT scan was 56 days (32-95) for those diagnosed antenatally (n=88) and 31 days (14-64) for diagnosed postnatally (n=9). The median length of follow up was 714 days (423-1607).

Patients with antenatally diagnosed CLMs managed conservatively (n=27) had a median LTH ratio of 5% (3-9). Those with antenatally diagnosed CLMs undergoing surgery (n=60) had a median LTH ratio of 13% (7-27). Patients with diagnosed postnatally CLMs (n=9) had a median LTH ratio of 52% (40-55). 1 patient with major anomalies was palliated and died shortly after delivery.

LTH ratio showed a significant negative correlation (P=0.0001) with patients' age at surgery (Table 1).

42% of patients with large CLMs (LTH ratio>20%) developed respiratory symptoms and 54% required surgery before 6 months of age. 7% of patients with small CLMs (LTH ratio≤ 5%) developed respiratory symptoms and none required surgery before 6 months of age (Table 2).

Conclusions:

Estimating lesion to hemithorax ratio using cross-sectional imaging can predict the likelihood of a patient developing respiratory symptoms and requiring early surgery before 6 months of age.

Table 1: Correlation of lesion volume and LTH ratio with age at surgery

Association with age of surgery (days)

Lesion volume (mls)

LTH ratio (%)

Kendall's tau

-0.338

-0.343

P value

0.0001

0.0001

Table 2: Effect of LTH ratio on development of symptoms and early surgery

LTH ratio (%)

≤5.0

5.1-10.0

10.1-20.0

>20.0

Number of patients

26

20

21

24

% Develop Symptoms

7

15

29

42

% Require early surgery (< 6 months)

0

0

10

54

% Require late surgery (≥6 months)

46

33

71

38