Yanchun Wang1, Zhen Li1, Daoyu Hu1, and Xiaoyan Meng1
1radiology, Tongji hospital, Wuhan, China, People's Republic of
Synopsis
Bladder cancer is the most common
malignant tumor of the urinary tract, and the incidence rate of bladder cancer
is 6% for men and 2% for women. Clinical treatment of bladder cancer depends
on the level of muscle invasion (stage T2 or higher) or non-invasion of the
muscle of the bladder wall (stage T1 or lower). Non-invasive tumors are
mainly treated with transurethral resection (TUR), whereas invasive
tumors are mainly treated with radical cystectomy . Therefore, it’s
important to precisely differentiate between non-muscle-invasive and
muscle-invasive bladder cancer before treatment. Purpose
To compare the imaging quality, diagnostic accuracy and ADC
values between reduced field-of-view diffusion-weighted imaging (rFOV DWI) and
single-shot echo-planar-imaging DWI (fFOV DWI) in non-muscle-invasive and
muscle-invasive bladder cancer.
Introduction
Bladder cancer is the most common malignant tumor of the urinary tract,
and the incidence rate of bladder cancer is 6% for men and 2% for women[1]. Clinical treatment
of bladder cancer depends on the level of muscle invasion (stage T2 or higher) or
non-invasion of the muscle of the bladder wall (stage T1 or
lower). Non-invasive tumors are mainly treated with transurethral resection
(TUR) [2], whereas invasive
tumors are mainly treated with radical cystectomy [3]. Therefore, it’s
important to precisely differentiate between non-muscle-invasive and
muscle-invasive bladder cancer before treatment.
Materials and Methods
This study was approved by the local institutional review board. All
patients gave written informed consent. 39 patients with a total of 60 bladder
tumors underwent rFOV and fFOV DWI. The pathologic and histologic grades
were determined for all tumors. Two
observers rated the two DWI image quality and specified ascore using a 4-point
scale (1, nondiagnostic; 4, excellent). Two radiologists who were blinded to
the pathology findings reviewed three
image sets (T2-weighted alone, T2-weighted plus fFOV DWI and T2-weighted plus
rFOV DWI), and assigned T stages and confidence levels for tumors of stage T2
or higher. The image quality scores for the two DWI sequences were assessed by
the Wilcoxon signed rank test. Differences in the diagnostic accuracy,
sensitivity, and specificity for each image set were evaluated using the
McNemar test. Differences in the performance were analyzed by comparing the areas
under the receiver operating characteristic curves (Az values). The Mann-Whitney
U test was used to compare the mean ADCs in the
relationship between the tumor stage and histologic grade.
Results
The average image quality scores were 3.62
and 2.98 on rFOV and fFOV DWI, respectively, a significant difference (P=0.000).
The diagnostic accuracies were 57%, 70%, 78% for T2-weighted images alone,
T2-weighted plus fFOV DWI and T2-weighted plus rFOV DWI, respectively. The overall accuracy,
specificity, and Az for diagnosing T2 or higher stages were
significantly improved by adding rFOV DWI (P<0.05). The mean ADC of muscle-invasive or G3 bladder cancers were
significantly lower than for non-muscle-invasive or G1ones
regardless of using fFOV or rFOV DWI (P<0.01).
Discussion and conclusion
rFOV DWI is
better compared to fFOV DWI regardless of imaging quality or diagnostic
accuracy, and it is more conducive to identify whether bladder cancer invades
the bladder muscle layer. And the ADC values can both be used to distinguish
non-muscle-invasive or G3 from muscle-invasive or G1 bladder cancers.
Acknowledgements
No acknowledgement found.References
References:
[1] G. Caruso, G. Salvaggio, A.
Campisi, D. Melloni, M. Midiri, M. Bertolotto, and R. Lagalla, Bladder tumor
staging: comparison of contrast-enhanced and gray-scale ultrasound. AJR Am J
Roentgenol 194 (2010) 151-6.
[2] D. Josephson, E. Pasin, and
J.P. Stein, Superficial bladder cancer: part 2. Management. Expert Rev
Anticancer Ther 7 (2007) 567-81.
[3] A. Sherif, M.N. Jonsson, and
N.P. Wiklund, Treatment of muscle-invasive bladder cancer. Expert Rev
Anticancer Ther 7 (2007) 1279-83.