Reducing the dose of gadolinium-based contrast agents for DCE-MRI guided SBRT: The effects on inter and intra observer variability for preoperative target volume delineation in early stage breast cancer patients.
BACKGROUND AND PURPOSE
This study aimed to determine the effects of reducing the dose of contrast agent (CA) in a DCE-MRI scan on inter- and intra-observer variability in the context of MRI-guided target volume delineation for stereotactic body radiation therapy of early stage breast cancer patients. This is in hopes of reducing risks to patients due to findings of residual CA in brain and bone.


MATERIALS AND METHODS
Twenty-three patients receiving neoadjuvant radiation therapy were enrolled. Five observers delineated the gross target volume (GTV) using DCE-MRI for guidance. 14/23 patients received the full clinical dose of CA and 9/23 received half. Clinical target volumes (CTV) were created through a 0.5 cm uniform expansion. Several metrics were used to quantify the inter and intra-observer reliability including differences in delineation volume and the reliability coefficient.


RESULTS
There were no significant differences in the volume, though half contrast patients had a lower median for both the GTV and CTV (difference of 0.26 cm3 and 1.27 cm3, respectively). All indicated a high degree of agreement between and within observers for both dose groups. However, the full dose group had a greater inter-observer variability, most likely due to the full CA causing more pronounced enhancement in the periphery.


CONCLUSIONS
Reducing the dose of contrast agent did not significantly alter inter- or intra-observer variability. These results have prompted our centre to reduce the dose of gadolinium in all patients enrolled in the SIGNAL trial.
['Mouawad|Matthew|M|', 'Biernaski|Heather|H|', 'Brackstone|Muriel|M|', 'Lock|Michael|M|', 'Yaremko|Brian|B|', 'Sexton|Tracy|T|', 'Yu|Edward|E|', 'Dinniwell|Robert E|RE|', 'Lynn|Kalan|K|', 'Hajdok|George|G|', 'Prato|Frank S|FS|', 'Thompson|Robert Terry|RT|', 'Gelman|Neil|N|', 'Gaede|Stewart|S|']
D000368:Aged D000369:Aged, 80 and over D001943:Breast Neoplasms D003287:Contrast Media D004305:Dose-Response Relationship, Drug D005260:Female D005682:Gadolinium D006801:Humans D008279:Magnetic Resonance Imaging D008875:Middle Aged D009367:Neoplasm Staging D015588:Observer Variation D016634:Radiosurgery D011880:Radiotherapy Planning, Computer-Assisted D061089:Radiotherapy, Image-Guided D015203:Reproducibility of Results D047368:Tumor Burden
Breast Gadolinium Magnetic Resonance Imaging Neoadjuvant therapy Observer variation Stereotactic Body Radiotherapy