title: Restaging locally advanced rectal cancer with MR imaging after chemoradiation therapy.
abstract: In recent years, preoperative therapy has become standard procedure for locally advanced rectal cancer. Tumor shrinkage due to preoperative chemotherapy-radiation therapy (CRT) is now a reality, and pathologically complete responses are not uncommon. Some researchers are now addressing organ preservation, thus increasing the demand for both functional and morphologic radiologic evaluation of response to CRT to distinguish responding from nonresponding tumors. On magnetic resonance (MR) images, post-CRT tumor morphologic features and volume changes have a high positive predictive value but a low negative predictive value for assessing response. Preliminary results indicate that diffusion-weighted MR imaging, especially at high b values, would be effective for prediction of treatment outcome and for early detection of tumor response. Some authors have reported that the use of apparent diffusion coefficient values in combination with other MR imaging criteria significantly improves discrimination between malignant and benign lymph nodes. Sequential determination of fluorodeoxyglucose uptake at positron emission tomography/computed tomography has proved useful in differentiating responding from nonresponding tumors during and at the end of CRT. However, radionuclide techniques have limitations, such as low spatial resolution and high cost. Large studies will be needed to verify the most effective morphologic and functional imaging modalities for post-CRT restaging of rectal cancer. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.303095085/-/DC1.
authors.affiliation: Department of Bioimaging and Radiological Sciences, Catholic University, School of Medicine, Largo A. Gemelli 1, 00168 Rome, Italy. bbarbaro@rm.unicatt.it
authors.forename: Brunella
authors.initials: B
authors.lastname: Barbaro
authors.forename: Renata
authors.initials: R
authors.lastname: Vitale
authors.forename: Lucia
authors.initials: L
authors.lastname: Leccisotti
authors.forename: Fabio M
authors.initials: FM
authors.lastname: Vecchio
authors.forename: Luisa
authors.initials: L
authors.lastname: Santoro
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Valentini
authors.forename: Claudio
authors.initials: C
authors.lastname: Coco
authors.forename: Fabio
authors.initials: F
authors.lastname: Pacelli
authors.forename: Antonio
authors.initials: A
authors.lastname: Crucitti
authors.forename: Roberto
authors.initials: R
authors.lastname: Persiani
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bonomo
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage*; D003131:Combined Modality Therapy; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000517:prevention & control*; D009367:Neoplasm Staging / Q000379:methods; D011379:Prognosis; D018714:Radiotherapy, Adjuvant; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents