title: Standardized Index of Shape (SIS): a quantitative DCE-MRI parameter to discriminate responders by non-responders after neoadjuvant therapy in LARC.
abstract: OBJECTIVE
  To investigate the potential of DCE-MRI to discriminate responders from non-responders after neoadjuvant chemo-radiotherapy (CRT) for locally advanced rectal cancer (LARC). We investigated several shape parameters for the time-intensity curve (TIC) in order to identify the best combination of parameters between two linear parameter classifiers.
  
  
  METHODS
  Seventy-four consecutive patients with LARC were enrolled in a prospective study approved by our ethics committee. Each patient gave written informed consent. After surgery, pathological TNM and tumour regression grade (TRG) were estimated. DCE-MRI semi-quantitative analysis (sqMRI) was performed to identify the best parameter or parameter combination to discriminate responders from non-responders in response monitoring to CRT. Percentage changes of TIC shape descriptors from the baseline to the presurgical scan were assessed and correlated with TRG. Receiver operating characteristic analysis and linear classifier were applied.
  
  
  RESULTS
  Forty-six patients (62.2%) were classified as responders, while 28 subjects (37.8%) were considered as non-responders. sqMRI reached a sensitivity of 93.5% and a specificity of 82.1% combining the percentage change in Maximum Signal Difference (ΔMSD) and Wash-out Slope (ΔWOS), the Standardized Index of Shape (SIS).
  
  
  CONCLUSIONS
  SIS obtains the best result in discriminating responders from non-responders after CRT in LARC, with a cut-off value of -3.0%.
  
  
  CONCLUSIONS
  • DCE-MRI shape descriptors are investigated to assess preoperative CRT response in LARC. • Identification of the best TIC shape descriptors combination through a linear classifier. • Identification of a single MRI index to predict neoadjuvant treatment response.
authors.affiliation: Division of Radiology, Department of Diagnostic Imaging, Radiant and Metabolic Therapy, "Istituto Nazionale Tumori Fondazione Giovanni Pascale - IRCCS", Via Mariano Semmola, 80131, Naples, Italy, a.petrillo@istitutotumori.na.it.
authors.forename: Antonella
authors.initials: A
authors.lastname: Petrillo
authors.forename: Roberta
authors.initials: R
authors.lastname: Fusco
authors.forename: Mario
authors.initials: M
authors.lastname: Petrillo
authors.forename: Vincenza
authors.initials: V
authors.lastname: Granata
authors.forename: Mario
authors.initials: M
authors.lastname: Sansone
authors.forename: Antonio
authors.initials: A
authors.lastname: Avallone
authors.forename: Paolo
authors.initials: P
authors.lastname: Delrio
authors.forename: Biagio
authors.initials: B
authors.lastname: Pecori
authors.forename: Fabiana
authors.initials: F
authors.lastname: Tatangelo
authors.forename: Gennaro
authors.initials: G
authors.lastname: Ciliberto
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000628:therapy*; D000328:Adult; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant / Q000379:methods; D003287:Contrast Media; D005260:Female; D006571:Heterocyclic Compounds; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods; D009942:Organometallic Compounds; D011446:Prospective Studies; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000473:pathology / Q000628:therapy*; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate