title: Diffusion volume (DV) measurement in endometrial and cervical cancer: A new MRI parameter in the evaluation of the tumor grading and the risk classification.
abstract: OBJECTIVE
  A new MRI parameter representative of active tumor burden is proposed: diffusion volume (DV), defined as the sum of all the voxels within a tumor with apparent diffusion coefficient (ADC) values within a specific range. The aims of the study were: (a) to calculate DV on ADC maps in patients with cervical/endometrial cancer; (b) to correlate DV with histological grade (G) and risk classification; (c) to evaluate intra/inter-observer agreement of DV calculation.
  
  
  METHODS
  Fifty-three patients with endometrial (n=28) and cervical (n=25) cancers underwent pelvic MRI with DWI sequences. Both endometrial and cervical tumors were classified on the basis of G (G1/G2/G3) and FIGO staging (low/medium/high-risk). A semi-automated segmentation procedure was used to calculate the DV. A freehand closed ROI outlined the whole visible tumor on the most representative slice of ADC maps defined as the slice with the maximum diameter of the solid neoplastic component. Successively, two thresholds were generated on the basis of the mean and standard deviation (SD) of the ADC values: lower threshold (LT="mean minus three SD") and higher threshold (HT="mean plus one SD"). The closed ROI was expanded in 3D, including all the contiguous voxels with ADC values in the range LT-HT × 10-3mm(2)/s. A Kruskal-Wallis test was used to assess the differences in DV among G and risk groups. Intra-/inter-observer variability for DV measurement was analyzed according to the method of Bland and Altman and the intraclass-correlation-coefficient (ICC).
  
  
  RESULTS
  DV values were significantly different among G and risk groups in both endometrial (p<0.05) and cervical cancers (p ≤ 0.01). For endometrial cancer, DV of G1 (mean ± sd: 2.81 ± 3.21 cc) neoplasms were significantly lower than G2 (9.44 ± 9.58 cc) and G3 (11.96 ± 8.0 cc) ones; moreover, DV of low risk cancers (5.23 ± 8.0 cc) were significantly lower than medium (7.28 ± 4.3 cc) and high risk (14.7 ± 9.9 cc) ones. For cervical cancer, DV of G1 (0.31 ± 0.13 cc) neoplasms was significantly lower than G3 (40.68 ± 45.65 cc) ones; moreover, DV of low risk neoplasms (6.98 ± 8.08 cc) was significantly lower than medium (21.7 ± 17.13 cc) and high risk (62.9 ± 51.12 cc) ones and DV of medium risk neoplasms was significantly lower than high risk ones. The intra-/inter-observer variability for DV measurement showed an excellent correlation for both cancers (ICC ≥ 0.86).
  
  
  CONCLUSIONS
  DV is an accurate index for the assessment of G and risk classification of cervical/endometrial cancers with low intra-/inter-observer variability.
authors.affiliation: IBB CNR, Napoli, Italy. Electronic address: pierpamainenti@hotmail.com.
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Mainenti
authors.affiliation: IBB CNR, Napoli, Italy.
authors.forename: Laura Micol
authors.initials: LM
authors.lastname: Pizzuti
authors.affiliation: Dipartimento di Scienze Biomediche Avanzate, Sezione di Radiologia, Università di Napoli "Federico II", Napoli, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Segreto
authors.affiliation: IBB CNR, Napoli, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Comerci
authors.affiliation: Dipartimento di Scienze Biomediche Avanzate, Sezione di Radiologia, Università di Napoli "Federico II", Napoli, Italy.
authors.forename: Simona De
authors.initials: S
authors.lastname: Fronzo
authors.affiliation: Dipartimento di Scienze Biomediche Avanzate, Sezione di Radiologia, Università di Napoli "Federico II", Napoli, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Romano
authors.affiliation: Dipartimento di Scienze Biomediche Avanzate, Sezione di Radiologia, Università di Napoli "Federico II", Napoli, Italy.
authors.forename: Vincenzina
authors.initials: V
authors.lastname: Crisci
authors.affiliation: Dipartimento di Scienze Biomediche Avanzate, Sezione di Radiologia, Università di Napoli "Federico II", Napoli, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Smaldone
authors.affiliation: Dipartimento di Scienze Biomediche Avanzate, Sezione di Radiologia, Università di Napoli "Federico II", Napoli, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Laccetti
authors.affiliation: IRCCS CROB, Rionero in Vulture, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Storto
authors.affiliation: IBB CNR, Napoli, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Alfano
authors.affiliation: Dipartimento di Scienze Biomediche Avanzate, Sezione di Radiologia, Università di Napoli "Federico II", Napoli, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Maurea
authors.affiliation: IRCCS SDN, Napoli, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Salvatore
authors.affiliation: Dipartimento di Medicina e Chirurgia, Università degli Studi di Salerno, Salerno, Italy.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Pace
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D016889:Endometrial Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008875:Middle Aged; D060787:Neoplasm Grading; D015588:Observer Variation; D012306:Risk; D012680:Sensitivity and Specificity; D047368:Tumor Burden; D002583:Uterine Cervical Neoplasms / Q000473:pathology*
keywords: ADC maps; Cancer; Cervical; DWI; Diffusion volume; Endometrial; MRI