Superiority of Deformable Image Co-registration in the Integration of Diagnostic Positron Emission Tomography-Computed Tomography to the Radiotherapy Treatment Planning Pathway for Oesophageal Carcinoma.
To investigate the use of image co-registration in incorporating diagnostic positron emission tomography-computed tomography (PET-CT) directly into the radiotherapy treatment planning pathway, and to describe the pattern of local recurrence relative to the PET-avid volume.



Fourteen patients were retrospectively identified, six of whom had local recurrence. The accuracy of deformable image registration (DIR) and rigid registration of the diagnostic PET-CT and recurrence CT, to the planning CT, were quantitatively assessed by comparing co-registration of oesophagus, trachea and aorta contours. DIR was used to examine the correlation between PET-avid volumes, dosimetry and site of recurrence.



Positional metrics including the dice similarity coefficient (DSC) and conformity index (CI), showed DIR to be superior to rigid registration in the co-registration of diagnostic and recurrence imaging to the planning CT. For diagnostic PET-CT, DIR was superior to rigid registration in the transfer of oesophagus (DSC=0.75 versus 0.65, P<0.009 and CI=0.59 versus 0.48, P<0.003), trachea (DSC=0.88 versus 0.65, P<0.004 and CI=0.78 versus 0.51, P<0.0001) and aorta structures (DSC=0.93 versus 0.86, P<0.006 and CI=0.86 versus 0.76, P<0.006). For recurrence imaging, DIR was superior to rigid registration in the transfer of trachea (DSC=0.91 versus 0.66, P<0.03 and CI=0.83 versus 0.51, P<0.02) and oesophagus structures (DSC=0.74 versus 0.51, P<0.004 and CI=0.61 versus 0.37, P<0.006) with a non-significant trend for the aorta (DSC=0.91 versus 0.75, P<0.08 and CI=0.83 versus 0.63, P<0.06) structure. A mean inclusivity index of 0.93 (range 0.79-1) showed that the relapse volume was within the planning target volume (PTVPET-CT); all relapses occurred within the high dose region.



DIR is superior to rigid registration in the co-registration of PET-CT and recurrence CT to the planning CT, and can be considered in the direct integration of PET-CT to the treatment planning process. Local recurrences occur within the PTVPET-CT, suggesting that this is a suitable target for dose-escalation strategies.
Medical Physics and Engineering, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK. Electronic address: Gillian.ward11@nhs.net.
G
G
Ward
Radiation Oncology, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
S
S
Ramasamy
Radiation Oncology and Medical Physics, Blacktown Hospital, Blacktown, Australia.
J R
JR
Sykes
Radiation Oncology, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
R
R
Prestwich
Clinical Radiology and Nuclear Medicine, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
F
F
Chowdhury
Clinical Radiology and Nuclear Medicine, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
A
A
Scarsbrook
Radiation Oncology, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
P
P
Murray
Radiation Oncology, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
K
K
Harris
Radiation Oncology, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
A
A
Crellin
Radiation Oncology, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
P
P
Hatfield
Radiation Oncology, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
D
D
Sebag-Montefiore
Biomedical Engineering Research Group, School of Engineering, Cardiff University, Cardiff, UK.
E
E
Spezi
Velindre Cancer Centre, Velindre Hospital, Cardiff, UK.
T
T
Crosby
Radiation Oncology, Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
G
G
Radhakrishna
D000368:Aged; D000369:Aged, 80 and over; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011874:Radiometry / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
Deformable image registration; PET-CT imaging; oesophageal cancer; pattern of local recurrence