Jing Gu1, Tao Chan1, Wailun LAW2, JingBo Zhang3, Pek-Lan Khong1
1Diagnostic Radiology, The University of Hong Kong, Hong Kong, China, People's Republic of; 2Colorectal Surgery, Queen Mary Hospital, the University of Hong Kong, Hong Kong, China, People's Republic of; 3Radiology, Memorial Sloan-Kettering Cancer Center, USA
As functional imaging modalities, DWI, DCE-MRI, and PET/CT have been applied in monitoring treatment response. However, the underlying biophysical basis for changes of imaging parameters during a course of chemoradiation therapy (CRT) is far from fully understood. An increase of apparent diffusion coefficient (ADC), a quantitative parameter from DWI, suggests treatment-induced cell lysis and necrosis. However, increase in ADC can also result from change in vessel permeability due to radiation therapy. For this, DCE-MRI may provide useful information. On the other hand, late decrease in ADC can be considered result of tissue compaction and fibrosis or presence of residual active disease, which may be distinguished by PET/CT. So the aim of this study was to investigate DWI, DCE-MRI and PET/CT for response assessment over a course of pre-operative combined CRT for primary rectal adenocarcinoma, to see if the combination of different techniques can best predict biological behavior and clinical outcome.