Interstitial Lung Disease in Systemic Sclerosis
Objectives Early diagnosis of interstitial lung disease (ILD), currently the main cause of death in systemic sclerosis (SSc), is needed. The gold standard is high-resolution CT (HRCT) of the chest, but regular screening faces the risk of increased radiation exposure. We performed a prospective validation of a dedicated, 9-slice HRCT protocol with reduced radiation dose for the detection of ILD in patients with SSc.
Methods We analysed 170/205 consecutive patients with SSc. Whole-chest HRCT, serving as standard of reference, and the reduced HRCT with nine slices allocated according to a basal–apical gradient were obtained. ILD presence, extent (> or <20%) and diagnostic confidence were assessed. The reduced HRCT was independently analysed by two blinded radiologists, who also evaluated image quality. Radiation dose parameters were calculated.
Results Standard chest HRCT showed ILD in 77/170 patients. With the reduced HRCT, 68/77 cases with ILD were identified (sensitivity 88.3%, both readers). The accuracy (91.8%, reader 1; 94.7%, reader 2), diagnostic confidence (98.8%, reader 1; 95.3%, reader 2) and image quality rates were high. Minimal ILD was correctly quantified in 73.1% (reader 1)/71.2% (reader 2) and extensive ILD in 88% (reader 1)/100% (reader 2). Importantly, the reduced HRCT had a significantly lower radiation dose. The mean dose length product (effective dose) was only 5.66±4.46 mGycm (0.08±0.06 mSv) compared with the standard protocol dose of 149.00±95.90 mGycm (2.09±1.34 mSv).
Conclusions The above-described reduced chest HRCT protocol reliably detects even mild SSc-ILD in clinical practice, with the advantage of a much lower radiation dose compared with standard whole-chest HRCT.
Interstitial lung disease (ILD) is frequent in patients with systemic sclerosis (SSc) and is the leading cause of disease-related death. Nowadays, high-resolution CT (HRCT) is the standard of reference for diagnosis of ILD. It allows an early detection of lung involvement, even from the subclinical stages. New methods enable a quantitative assessment and favour the use of HRCT for longitudinal studies.
On the downside, CT uses ionising radiation, which has been linked to an increased cancer risk. As patients with SSc are often screened annually, dose reduction is an important issue. In the last decade, many methods have been introduced to lower the radiation dose by maintaining diagnostic image quality. Lowering tube current is the most widely employed approach in chest CT. Alternatively, the number of slices can be reduced by performing a sequential CT protocol.
In an earlier, smaller, retrospective study, our group evaluated 'virtually' calculated series with a reduced number of slices for the detection and quantification of ILD. The results were promising, showing a high accuracy for the detection of SSc-ILD.
The goals of this prospective study were therefore (1) to evaluate the robustness of the scan protocol concerning image acquisition; (2) to analyse the accuracy of a reduced chest scan with limited number of HRCT slices compared with a standard HRCT of the entire chest for the detection and quantification of ILD in patients with SSc and to validate thereby the results of the first retrospective study in a larger, prospective cohort and (3) to measure the reduction in radiation dose versus standard HRCT.
Abstract and Introduction
Abstract
Objectives Early diagnosis of interstitial lung disease (ILD), currently the main cause of death in systemic sclerosis (SSc), is needed. The gold standard is high-resolution CT (HRCT) of the chest, but regular screening faces the risk of increased radiation exposure. We performed a prospective validation of a dedicated, 9-slice HRCT protocol with reduced radiation dose for the detection of ILD in patients with SSc.
Methods We analysed 170/205 consecutive patients with SSc. Whole-chest HRCT, serving as standard of reference, and the reduced HRCT with nine slices allocated according to a basal–apical gradient were obtained. ILD presence, extent (> or <20%) and diagnostic confidence were assessed. The reduced HRCT was independently analysed by two blinded radiologists, who also evaluated image quality. Radiation dose parameters were calculated.
Results Standard chest HRCT showed ILD in 77/170 patients. With the reduced HRCT, 68/77 cases with ILD were identified (sensitivity 88.3%, both readers). The accuracy (91.8%, reader 1; 94.7%, reader 2), diagnostic confidence (98.8%, reader 1; 95.3%, reader 2) and image quality rates were high. Minimal ILD was correctly quantified in 73.1% (reader 1)/71.2% (reader 2) and extensive ILD in 88% (reader 1)/100% (reader 2). Importantly, the reduced HRCT had a significantly lower radiation dose. The mean dose length product (effective dose) was only 5.66±4.46 mGycm (0.08±0.06 mSv) compared with the standard protocol dose of 149.00±95.90 mGycm (2.09±1.34 mSv).
Conclusions The above-described reduced chest HRCT protocol reliably detects even mild SSc-ILD in clinical practice, with the advantage of a much lower radiation dose compared with standard whole-chest HRCT.
Introduction
Interstitial lung disease (ILD) is frequent in patients with systemic sclerosis (SSc) and is the leading cause of disease-related death. Nowadays, high-resolution CT (HRCT) is the standard of reference for diagnosis of ILD. It allows an early detection of lung involvement, even from the subclinical stages. New methods enable a quantitative assessment and favour the use of HRCT for longitudinal studies.
On the downside, CT uses ionising radiation, which has been linked to an increased cancer risk. As patients with SSc are often screened annually, dose reduction is an important issue. In the last decade, many methods have been introduced to lower the radiation dose by maintaining diagnostic image quality. Lowering tube current is the most widely employed approach in chest CT. Alternatively, the number of slices can be reduced by performing a sequential CT protocol.
In an earlier, smaller, retrospective study, our group evaluated 'virtually' calculated series with a reduced number of slices for the detection and quantification of ILD. The results were promising, showing a high accuracy for the detection of SSc-ILD.
The goals of this prospective study were therefore (1) to evaluate the robustness of the scan protocol concerning image acquisition; (2) to analyse the accuracy of a reduced chest scan with limited number of HRCT slices compared with a standard HRCT of the entire chest for the detection and quantification of ILD in patients with SSc and to validate thereby the results of the first retrospective study in a larger, prospective cohort and (3) to measure the reduction in radiation dose versus standard HRCT.
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