Repetitive assessment of low-dose MDCT in patients with cystic fibrosis
Brody scores and respective bronchiectasis-,
mucus-plugging-,
peribronchial-thickening-,
parenchymal-opacity-,
and hyperinflation subscores were assessed twice (time interval,
28 days to 7 years) by each of 3 independent radiologists (R1,
R2,
and R3,
with 1-20 years of professional experience in diagnostic radiology) in low-dose multidetector-row CTs of the chest (LDCT,
4-64 rows,
120 KVp,
10-15 mAs/slice,
CTDIw appr.
1.0 mGy,
effective dose appr.
0.5 mSv) performed in inspiration in 15 consecutive adult patients suffering from CF-related lung disease,
who each had only had one LDCT examination in our institution (8 female,
7 male,
age,
18-50 years,
mean,
33 years).
The clinical indication for LDCT was to evaluate current lung morphology status or there was clinical suspicion or evidence of aggravation of CF-related lung damage.
Image evaluation
Coronal and axial images (slice thickness 3 mm and 1.5 mm) of each patient were obtained from the picture-archiving-and-communication system (PACS) and assessed side-by-side on two 21-inch-1k-PACS monitors,
with one image per display,
at window width and window level settings of 1,600 HU and -600 HU (lung window),
respectively.
Sagittal images were only analyzed to match findings when this was not achievable on axial or coronal images alone.
The Brody scoring system for HRCT in cystic fibrosis
The “Brody score” is a weighted composite (total) score for CF-related alterations in lung structure that characterizes and quantifies the respective presence,
location,
and extent of bronchiectasis,
mucus plugging,
peribronchial thickening,
parenchymal opacity,
and hyperinflation each in the periphery and in the center of the upper,
lower and middle right and left lung lobes,
respectively.
The lingual segment is considered to represent the left middle lobe.
The Brody score has a possible range from 0 to 207.00 points,
at increments of 0.25 points.
The score increases with the severity of damage in lung structure caused by CF [10] (see also Appendix,
Table 7).
The Brody score was originally designed to estimate lung morphology in incremental HRCT scans performed in both inspiration and expiration in children (6 to 10 years) [10].
In our study,
in contrast to Brody and co-workers [10],
only adult CF patients were considered.
Both parenchymal opacity and hyperinflation were only evaluated in LDCT scans performed in inspiration.
Statistical evaluation
The basis for our statistical description was a modified Bland-Altmann-Plot [14].
Average values of the six individual scoring results (two each for R1-R3) of the Brody score and its five different sub-scores [10] were plotted along the x-axis.
Deviation of each individual scoring result from the average was plotted along the y-axis of the modified Bland-Altmann-Plots for the Brody score and its five different sub-scores.
Both the absolute deviations (in Brody-scoring points) and the relative deviations (in percent of the mean) were descipted.
Institutional ethics committee permission was received for the retrospective analysis of data previously obtained for individual clinical treatment of patients suffering from CF.
Data contained in this study were estimated,
both for presentation of test results and statistical analysis,
in consensus with the World Medical Association (WMA) Declaration of Helsinki Ethical Principles for Medical Research Involving Human Subjects,
as last modificated by the 59th WMA General Assembly,
Seoul,
Korea,
October 2008.