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Quantitative aspects of diffusion-weighted magnetic resonance imaging in rectal cancer response to neoadjuvant therapy

Thiago Bassaneze
Thiago Bassaneze
, 
José Eduardo Gonçalves
José Eduardo Gonçalves
, 
Juliano Ferreira Faria
Juliano Ferreira Faria
, 
Rogério Tadeu Palma
Rogério Tadeu Palma
 and 
Jaques Waisberg
Jaques Waisberg
   | Jun 25, 2017
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Article Category: Research Article
Published Online: Jun 25, 2017
Page range: 270 - 276
Received: Dec 06, 2016
Accepted: Jun 01, 2017
DOI: https://doi.org/10.1515/raon-2017-0025
© 2017 Thiago Bassaneze, José Eduardo Gonçalves, Juliano Ferreira Faria, Rogério Tadeu Palma, Jaques Waisberg
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1

Sample of a T2-weighted MRI, DW-MRI (b-value 1000 s/mm2), and ADC map from a locally advanced rectal tumor. The red arrows point to different aspects of the left lateral pre-CRT tumor area. The yellow arrows point to the cancer shrinkage in the post-CRT. Pre- and post-CRT ADC values were 0.92 × 10−3 mm2/s and 1.50 × 10−3 mm2/s, with pCR in the surgical specimen.
Sample of a T2-weighted MRI, DW-MRI (b-value 1000 s/mm2), and ADC map from a locally advanced rectal tumor. The red arrows point to different aspects of the left lateral pre-CRT tumor area. The yellow arrows point to the cancer shrinkage in the post-CRT. Pre- and post-CRT ADC values were 0.92 × 10−3 mm2/s and 1.50 × 10−3 mm2/s, with pCR in the surgical specimen.

Figure 2

Correlation between ADC values and final T staging. (A) The pre-CRT ADC values were similar in the different groups (blue bars, (p > 0.05), although post-CRT ADC values differed in each group (green bars, p < 0.01); statistical significance (*). (B) Post-CRT ADC values with a moderate negative correlation and slope different from zero degrees (Spearman’s Rho = -0.54; 95% confidence interval -0.75 to -0.24). (C) Box plot analysis between post-CRT ADC values and final T staging. The pCR ADC-median value (1.53 × 10’−3 mm2/s) is far away from the lower and upper boundaries of the non-pCR box (p < 0.01).
Correlation between ADC values and final T staging. (A) The pre-CRT ADC values were similar in the different groups (blue bars, (p > 0.05), although post-CRT ADC values differed in each group (green bars, p < 0.01); statistical significance (*). (B) Post-CRT ADC values with a moderate negative correlation and slope different from zero degrees (Spearman’s Rho = -0.54; 95% confidence interval -0.75 to -0.24). (C) Box plot analysis between post-CRT ADC values and final T staging. The pCR ADC-median value (1.53 × 10’−3 mm2/s) is far away from the lower and upper boundaries of the non-pCR box (p < 0.01).

Figure 3

Receiver operating characteristic (ROC) curve and histogram in patients with rectal carcinoma with a normal distribution. (A) The optimal post-CRT ADC cutoff value 1.49 × 10−3 mm2/s (area under the curve = 0.95). (B) Histogram. The mean post-CRT ADC values of patients with pCR was 1.53 (± 1.96 × 0.15 × 10−3 mm2/s) and of patients with non-pCR 1.16 (± 1.96 × 0.19 × 10−3 mm2/s); the area in gray highlights the possible overlap in these values.
Receiver operating characteristic (ROC) curve and histogram in patients with rectal carcinoma with a normal distribution. (A) The optimal post-CRT ADC cutoff value 1.49 × 10−3 mm2/s (area under the curve = 0.95). (B) Histogram. The mean post-CRT ADC values of patients with pCR was 1.53 (± 1.96 × 0.15 × 10−3 mm2/s) and of patients with non-pCR 1.16 (± 1.96 × 0.19 × 10−3 mm2/s); the area in gray highlights the possible overlap in these values.

Calculation of diagnostic performance of conventional T2W MRI and combined set of conventional T2W MRI in addition to DWI for the diagnosis of complete rectal cancer response to neoadjuvant therapy

T2W 95% CI T2W + DWI 95% CI
Sensitivity% 86.9 (0.65−0.96) 96.1 (0.78−0.99)
Specificity% 50 (0.20−0.79) 71.4 (0.30−0.94)
PPV% 80 (0.58−0.92) 92.6 (0.74−0.98)
NPV% 62.5 (0.25−0.89) 83.3 (0.36−0.99)
Accuracy% 75.7 (0.57−0.88) 81.8 (0.63−0.92)

The patients’ clinical characteristics and patohystologic characteristics of the tumor

All pCR non-pCR
Average age, years 59.6 ±11.5 58.5 ±11.2 59.9 ±11.8
Gender

= number of individuals; CRT = chemoradiotherapy; pCR = pathologic complete response
   Male 18 5 13
   Female 15 2 13
Clinical T stage pre-CRT (MRI classification)

= number of individuals; CRT = chemoradiotherapy; pCR = pathologic complete response
   T2 3 1 2
   T3 23 5 18
   T4 7 1 6
Average tumor distance to the anus (cm)

= number of individuals; CRT = chemoradiotherapy; pCR = pathologic complete response

 5.1 (± 2.2) 6.1 (± 1.3) 4.8 (± 2.3)
Type of resection

= number of individuals; CRT = chemoradiotherapy; pCR = pathologic complete response
   Low anterior resection 15 3 12
   Abdominoperineal resection 15 4 11
   Pelvic exenteration 3 0 3
Histologic grade (biopsy)

= number of individuals; CRT = chemoradiotherapy; pCR = pathologic complete response
   Well differentiated 6 2 4
   Moderately differentiated 23 4 19
   Poorly differentiated 4 1 3
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