Locally advanced rectal cancer: is diffusion weighted MRI helpful for the identification of complete responders (ypT0N0)
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ONCOLOGY
Locally advanced rectal cancer: is diffusion weighted MRI helpful for the identification of complete responders (ypT0N0) after neoadjuvant chemoradiation therapy? S. Sassen & M. de Booij & M. Sosef & R. Berendsen & G. Lammering & R. Clarijs & M. Bakker & R. Beets-Tan & F. Warmerdam & R. Vliegen
Received: 23 January 2013 / Revised: 14 May 2013 / Accepted: 30 May 2013 # European Society of Radiology 2013
Abstract Objectives To determine retrospectively the additional value of DWI-MRI toT2-MRI for predicting complete response (ypT0N0 = CR) after chemoradiation-therapy (CRT) in locally advanced rectal cancer. S. Sassen (*) : M. de Booij : R. Vliegen Department of Radiology, Atrium Medical Center Parkstad, P.O. Box 4446, 6401 CX Heerlen, The Netherlands e-mail: [email protected] M. Sosef Department of General Surgery, Atrium Medical Center Parkstad, P.O. Box 4446, 6401 CX Heerlen, The Netherlands R. Berendsen Department of Clinical Physics, Atrium Medical Center Parkstad, P.O. Box 4446, 6401 CX Heerlen, The Netherlands G. Lammering Department of Radiation Oncology, MAASTRO Clinic, P.O. Box 3035, 6202 NA Maastricht, The Netherlands R. Clarijs Department of Pathology, Atrium Medical Center Parkstad, P.O. Box 4446, 6401 CX Heerlen, The Netherlands M. Bakker Department of Gastroenterology and Hepatology, Atrium Medical Center Parkstad, P.O. Box 4446, 6401 CX Heerlen, The Netherlands R. Beets-Tan Department of Radiology, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands F. Warmerdam Department of Internal Medicine/Oncology, Atrium Medical Center Parkstad, P.O. Box 4446, 6401 CX Heerlen, The Netherlands
Methods Seventy locally advanced rectal cancer patients underwent CRT followed by restaging MRI and resection. Two readers with different experience levels independently scored T2 images for CR and, in a second reading, combined T2 and DWI. A 5-point confidencelevel score was used to generate ROC curves. Areas under the ROC curves (AUC) and interobserver agreement were compared for both readings. Histology served as reference standard. Results The interobserver agreement increased after addition of DWI from 0.35 to 0.58 but the AUC improved only for the experienced reader (0.77 to 0.89, p=0.005 vs. 0.74 to 0.70, p>0.05). Sensitivity and NPV improved from 20-30 % to 4070 %, respectively 88 % to 91-95 %. Specificity and PPV improved only for the experienced reader (87 to 93 % respectively 27 to 63 %). Conclusion Adding DWI to T2-MRI improves consistency between readers and has potential to improve readers’ accuracy dependent on his/her experience. DWI could be of additional value, particularly in ruling out CR (high NPV), but considering the sub-optimal PPV one should be cautious about relying solely on MRI for the clinical decision to offer a wait-and-see strategy. Key Points • Diffusion-weighted magnetic resonance imaging is increasingly used to assess rectal tumours • Adding DWI to T2-MRI potentially improves diagnostic accuracy for identifying complete responders • Add
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