Abstract
Purpose
This study evaluated intraobserver and interobserver variability in the measurement of apparent diffusion coefficient (ADC) values in breast carcinomas.
Materials and methods
Twenty-eight patients with solid breast lesions >10 mm underwent conventional contrast-enhanced magnetic resonance imaging (MRI) and diffusion-weighted MRI (DW-MRI). Two observers (expert and trainee) segmented the lesion from the surrounding breast tissue on DW images with high b-value (1,000 s/mm2). This analysis was repeated by the expert reader after 6 months. Volumes were analysed to obtain mean, median and standard deviation (SD) of the ADC values. Interobserver and intraobserver variation was analysed using the Bland-Altman graph.
Results
All lesions were breast carcinomas, with a mean ADC value of 1.07 × 10−3 mm2/s. The mean of the differences was 0.012 × 10−3 mm2/s, corresponding to an intraobserver variability of 1.1% (limits of agreement: −5%/+8%). The mean interobserver difference was 0.022 × 10−3 mm2/s, corresponding to an interobserver variability of 2% (limits of agreement: −9%/+14%).
Conclusions
We found a low intraobserver and interobserver variability in calculating ADC in breast carcinomas, which supports its potential use in routine clinical practice.
Riassunto
Obiettivo
Obiettivo del nostro lavoro è stato determinare la variabilità intra-osservatore e inter-osservatore nel calcolo del coefficiente di diffusione apparente (ADC) nei carcinomi mammari (CM).
Materiali e metodi
Ventotto pazienti con lesioni mammarie solide >10 mm sono state sottoposte a risonanza magnetica (RM) convenzionale con mezzo di contrasto e a RM pesata in diffusione (RM-DW). Due osservatori hanno isolato la lesione dal tessuto mammario circostante nelle sequenze con elevata pesatura in diffusione (b-value=1000 s/mm2); tale analisi è stata ripetuta da un osservatore dopo 6 mesi. Per i volumi ottenuti sono state calcolate media, mediana e deviazione standard dell’ADC. La variabilità intra-osservatore e la variabilità inter-osservatore sono state valutate tramite il metodo di Bland e Altman.
Risultati
Tutte le lesioni sono risultate CM, con un valore medio di ADC di 1,07×10−3 mm2/s. è stata calcolata una media delle differenze di 0,012×10−3 mm2/s, corrispondente ad una variabilità intra-osservatore di 1,1% (limiti di accordo −5%/+8%). È stata calcolata una media delle differenze di 0,022×10−3 mm2/s, corrispondente ad una variabilità inter-osservatore di 2% (limiti di accordo di −9%/+14%).
Conclusioni
È stata osservata una bassa variabilità intraosservatore e inter-osservatore per il calcolo dell’ADC nei CM, la quale supporta un suo possibile utilizzo nella routine clinica.
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Petralia, G., Bonello, L., Summers, P. et al. Intraobserver and interobserver variability in the calculation of apparent diffusion coefficient (ADC) from diffusion-weighted magnetic resonance imaging (DW-MRI) of breast tumours. Radiol med 116, 466–476 (2011). https://doi.org/10.1007/s11547-011-0616-z
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DOI: https://doi.org/10.1007/s11547-011-0616-z
Keywords
- Breast carcinoma
- Diffusion-weighted magnetic resonance imaging
- Intraobserver variability
- Interobserver variability