title: The potential predictive value of MRI and PET-CT in mucinous and nonmucinous rectal cancer to identify patients at high risk of metastatic disease.
abstract: OBJECTIVE
  To correlate imaging parameters from baseline MRI diffusion-weighted imaging (DWI) and fludeoxyglucose (FDG) positron emission tomography (PET)-CT with synchronous and metachronous metastases in mucinous carcinoma (MC) and non-mucinous carcinoma (NMC) rectal cancer.
  
  
  METHODS
  111 patients with extraperitoneal locally advanced rectal cancer, who underwent pelvic MRI, DWI and FDG PET-CT, were stratified into MC (n = 23) and NMC (n = 88). We correlated adverse morphologic features on MRI [mT4, mesorectal fascia involvement, extramural venous invasion (mEMVI), mN2] and quantitative imaging parameters [minimum apparent diffusion coefficient (ADCmin), maximum standardized uptake value, total lesion glycolysis, metabolic tumour volume, T2weighted and DWI tumour volumes] with the presence of metastatic disease. All patients underwent pre-operative chemoradiation therapy (CRT); 100/111 patients underwent surgery after CRT and were classified as pathological complete response (PCR) and no PCR [tumour regression grade (TRG)1 vs TRG2-5] and as ypN0 and ypN1-2. Median follow-up time was 48 months. Metastases were confirmed on FDG PET-CT and contrast-enhanced multidetector CT.
  
  
  RESULTS
  The percentage of mucin measured by MRI correlates with that quantified by histology. On multivariate analysis, the synchronous metastases were correlated with mEMVI [odds ratio (OR) = 21.48, p < 0.01] and low ADCmin(OR = 0.04, p = 0.038) in NMC. The difference of metachronous recurrence between the MC group (10-90% mucin) and NMC group was significant (p < 0.01) (OR = 21.67, 95% confidence interval 3.8-120.5). Metachronous metastases were correlated with ypN2 (OR = 8.24, p = 0.01) in MC and in NMC. In NMC, mEMVI correlated with no PCR (p = 0.018) and ypN2 (p < 0.01).
  
  
  CONCLUSIONS
  mEMVI could identify patients with NMC, who are at high risk of synchronous metastases. The MC group is at a high risk of developing metachronous metastases. Advances in knowledge: Patients at high risk of metastases are more likely to benefit from more aggressive neoadjuvant therapy.
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Brunella
authors.initials: B
authors.lastname: Barbaro
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Leccisotti
authors.affiliation: 2 Department of Pathology, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Fabio M
authors.initials: FM
authors.lastname: Vecchio
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Marialuisa
authors.initials: M
authors.lastname: Di Matteo
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Serra
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Salsano
authors.affiliation: 4 Department of Hygiene, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Poscia
authors.affiliation: 3 Department of Surgery, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Coco
authors.affiliation: 3 Department of Surgery, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Persiani
authors.affiliation: 3 Department of Surgery, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Alfieri
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Gambacorta
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Valentini
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Giordano
authors.affiliation: 1 Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bonomo
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059248:Chemoradiotherapy / Q000379:methods; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D009361:Neoplasm Invasiveness / Q000473:pathology; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D016609:Neoplasms, Second Primary / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D018570:Risk Assessment; D018709:Statistics, Nonparametric; D016019:Survival Analysis
chemical_list: D019788:Fluorodeoxyglucose F18