Fig 1.
DWI = diffusion-weighted imaging; EBRT = external bean radiotherapy; IGBT = image-guided brachytherapy; MRI = magnetic resonance imaging.
Fig 2.
MRI of a 55-year-old female with stage IIIc1 adenocarcinoma of the cervix.
(A) Axial T2-weighted image showing a solid mass, slightly hyperintense relative to the low signal of the cervical stroma. (B) The tumor appears bright on a high b-value diffusion-weighted image (b-value 800; B) and dark on the apparent diffusion coefficient (ADC) map (C). A large region of interest (L-ROI) was drawn freehand to cover the whole tumor on a single slice, with an ADC of 920 mm2/s. (D) Three small ROIs (5 mm diameter) were drawn on the areas of the tumor showing the greatest restriction on the same slice, with an ADC of 807 mm2/s. The patient had complete response after treatment.
Fig 3.
MRI of a 55-year-old female with stage IIIc1 adenocarcinoma of the cervix.
(A) Pretreatment sagittal T2-weighted image showing a large solid tumor with a moderate T2-signal. The tumor appears bright on a high B-value diffusion weighted image (b 1000; B) and dark on the apparent diffusion coefficient (ADC) map (C), with an ADC for the large region of interest (L-ROImean) of 963 mm2/s. (D) A large tumor is still visible after external beam radiotherapy. The ADC is 1057 mm2/s, corresponding to an increase of 10%. (E) By the time of third imaging during image-guided brachytherapy, the tumor has reduced in size. (F, G, H) A small residual tumor is visible after treatment with an ADC of 625 mm2/s. Despite the presence of a small residual tumor, the patient remained stable after treatment and no recurrence has been detected.
Table 1.
Clinicopathological characteristics of the patients.
Characteristics of all patients with diffusion weighted MRIs before treatment and post-EBRT (n = 52) and the subgroup of them with MRIs at all six timepoints: pretreatment, post-EBRT and concurrent chemotherapy, during IGBT and after completing the whole treatment course (n = 28) are shown separately.
Fig 4.
Mean apparent diffusion coefficients and their changes during treatment in whole tumor ROIs.
The measurements were derived from large regions of interest (L-ROIs) covering the whole tumor drawn by two independent observers. The graph shows the mean value for the L-ROI, with values for observer 1 in blue and those for observer 2 in red. ADC = apparent diffusion coefficient; EBRT = external beam radiotherapy; IGBT = image-guided brachytherapy; L-ROImean = mean ADC for the large regions of interest; SD = standard deviation.
Fig 5.
Mean apparent diffusion coefficients and their changes during treatment in small ROIs.
Measurements were taken from three small regions of interest (S-ROIs) with a diameter of 5 mm placed on areas of tumor showing greatest restriction by two independent observers. The graph shows the lowest mean value of the three regions. ADC = apparent diffusion coefficient; EBRT = external beam radiotherapy; IGBT = image-guided brachytherapy; S-ROImean = mean ADC for the small regions of interest; SD = standard deviation.
Table 2.
Intraclass correlation coefficient of the ADC measurements between observers 1 and 2.
Table 3.
Associations of intratumoral pretreatment and post-EBRT apparent diffusion coefficient (ADC) values with clinical variables and the significance of the changes in ADC values between time points.
All 52 patients underwent DWI post-EBRT, but only 37 patients had a measurable residual tumor.
Fig 6.
Univariate analysis of cumulative overall survival according to the relative change in ADC values from pretreatment to post-EBRT MRI scan using intratumoral S-ROIs.
ADC value difference between the pretreatment and post-EBRT scans was dichotomized using ROC curve to define the Youden index providing the cutoff value of 197.5 mm2/s. Blue line indicates group of patients with an increase of over 197.5 mm2/s in ADC values (n = 14). Red line indicates group of patients with an increase of less than 197.5 mm2/s in ADC values (n = 23) An increase in the ADC of over 197.5 mm2/s for S-ROImin predicted better overall survival (P = 0.018).