Value of MRI and diffusion-weighted MRI for the diagnosis of locally recurrent rectal cancer.
OBJECTIVE
To evaluate the accuracy of standard MRI, diffusion-weighted MRI (DWI) and fusion images for the diagnosis of locally recurrent rectal cancer in patients with a clinical suspicion of recurrence.


METHODS
Forty-two patients with a clinical suspicion of recurrence underwent 1.5-T MRI consisting of standard T2-weighted FSE (3 planes) and an axial DWI (b0,500,1000). Two readers (R1,R2) independently scored the likelihood of recurrence; [1] on standard MRI, [2] on standard MRI+DWI, and [3] on T2-weighted+DWI fusion images.


RESULTS
19/42 patients had a local recurrence. R1 achieved an area under the ROC-curve (AUC) of 0.99, sensitivity 100% and specificity 83% on standard MRI versus 0.98, 100% and 91% after addition of DWI (p = 0.78). For R2 these figures were 0.87, 84% and 74% on standard MRI and 0.91, 89% and 83% with DWI (p = 0.09). Fusion images did not significantly improve the performance. Interobserver agreement was κ0.69 for standard MRI, κ0.82 for standard MRI+DWI and κ0.84 for the fusion images.


CONCLUSIONS
MRI is accurate for the diagnosis of locally recurrent rectal cancer in patients with a clinical suspicion of recurrence. Addition of DWI does not significantly improve its performance. However, with DWI specificity and interobserver agreement increase. Fusion images do not improve accuracy.
Department of Radiology, Maastricht University Medical Centre, P.O. Box 5800, 6202 AZ, Maastricht, The Netherlands.
Doenja M J
DM
Lambregts
Vincent C
VC
Cappendijk
Monique
M
Maas
Geerard L
GL
Beets
Regina G H
RG
Beets-Tan
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D012004:Rectal Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
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