tPurpose: 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) valueswithin a specific range. The aims of the study were: (a) to calculate DV on ADC maps in patients withcervical/endometrial cancer; (b) to correlate DV with histological grade (G) and risk classification; (c) toevaluate intra/inter-observer agreement of DV calculation.Materials and methods: Fifty-three patients with endometrial (n = 28) and cervical (n = 25) cancers under-went pelvic MRI with DWI sequences. Both endometrial and cervical tumors were classified on the basisof 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 out-lined the whole visible tumor on the most representative slice of ADC maps defined as the slice with themaximum diameter of the solid neoplastic component. Successively, two thresholds were generated onthe basis of the mean and standard deviation (SD) of the ADC values: lower threshold (LT = “mean minusthree SD”) and higher threshold (HT = “mean plus one SD”). The closed ROI was expanded in 3D, includingall the contiguous voxels with ADC values in the range LT-HT × 10–3 mm2/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 Blandand Altman and the intraclass-correlation–coefficient (ICC).Results: DV values were significantly different among G and risk groups in both endometrial (p < 0.05) andcervical cancers (p ≤ 0.01). For endometrial cancer, DV of G1 (mean ± sd: 2.81 ± 3.21 cc) neoplasms weresignificantly 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 ± 45.65cc) 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 significantlylower than high risk ones.The intra-/inter-observer variability for DV measurement showed an excellent correlation for bothcancers (ICC ≥ 0.86).Conclusions: DV is an accurate index for the assessment of G and risk classification of cervical/endometrialcancers with low intra-/inter-observer variability.
Diffusion volume (DV) measurement in endometrial and cervical cancer: A new MRI parameter in the evaluation of the tumor gradingand the risk classification
Leonardo Pace
2016-01-01
Abstract
tPurpose: 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) valueswithin a specific range. The aims of the study were: (a) to calculate DV on ADC maps in patients withcervical/endometrial cancer; (b) to correlate DV with histological grade (G) and risk classification; (c) toevaluate intra/inter-observer agreement of DV calculation.Materials and methods: Fifty-three patients with endometrial (n = 28) and cervical (n = 25) cancers under-went pelvic MRI with DWI sequences. Both endometrial and cervical tumors were classified on the basisof 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 out-lined the whole visible tumor on the most representative slice of ADC maps defined as the slice with themaximum diameter of the solid neoplastic component. Successively, two thresholds were generated onthe basis of the mean and standard deviation (SD) of the ADC values: lower threshold (LT = “mean minusthree SD”) and higher threshold (HT = “mean plus one SD”). The closed ROI was expanded in 3D, includingall the contiguous voxels with ADC values in the range LT-HT × 10–3 mm2/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 Blandand Altman and the intraclass-correlation–coefficient (ICC).Results: DV values were significantly different among G and risk groups in both endometrial (p < 0.05) andcervical cancers (p ≤ 0.01). For endometrial cancer, DV of G1 (mean ± sd: 2.81 ± 3.21 cc) neoplasms weresignificantly 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 ± 45.65cc) 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 significantlylower than high risk ones.The intra-/inter-observer variability for DV measurement showed an excellent correlation for bothcancers (ICC ≥ 0.86).Conclusions: DV is an accurate index for the assessment of G and risk classification of cervical/endometrialcancers with low intra-/inter-observer variability.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
