Diffusion Weighted and Dynamic Contrast Enhanced Magnetic Resonance Imaging in Carcinoma of Cervix: Role of Apparent Diffusion Coefficient Value and Time Intensity Curve Pattern in Chemoradiotherapeutic Response Evaluation

Introduction: Magnetic resonance imaging (MRI) is a widely used imaging modality in the imaging evaluation of carcinoma of cervix. The aim of our study was to evaluate the response in carcinoma cervix patients following chemoradiotherapy by Diffusion weighted (DW-MRI) and Dynamic contrast enhanced-MRI (DCE-MRI). Methods: 21 inoperable biopsy proven patients (mean age 48.43 years) of carcinoma cervix were included in the study. All patients underwent MRI (conventional, DW and DCE) of the pelvis thrice. Baseline MRI, Post chemotherapy MRI after neoadjuvant chemotherapy and Post chemoradiotherapy MRI after completion of concurrent chemoradiotherapy. Post treatment apparent diffusion coefficient(ADC) values and Time intensity curve(TIC) pattern were compared with baseline values. Results: Baseline meanADC value of all patients was 0.82 x10-3 mm2/s. After completion of treatment, 18 patients showed complete resolution of tumor and showed 0.50 x10-3 mm2/s increase in meanADC value from baseline MRI which was significantly higher than remaining 3 patients with residual tumor (0.50 x10-3 mm2/s v/s 0.17 x10-3 mm2/s). ADC threshold value of 1.15 x10-3 mm2/s was defined, differentiating the residual tumor from the healthy cervical tissue after chemoradiation. On post treatment MRI, 17 out of 18 patients with complete resolution of tumor showed increasing trend of enhancement on TIC and only one patient showed plateau pattern. 2 of the 3 patients with residual tumor showed washout pattern and one patient showed plateau pattern. Conclusion: ADC values and TIC pattern differ in patients with complete response to chemoradiotherapy from patients with residual tumor, so helps in differentiating residual tumor from cancer free cervix. Keywords: Carcinoma of cervix; Chemoradiotherapy; Diffusion weighted MRI; Dynamic contrast enhanced MRI; Time intensity curve.

Amide Proton Transfer Weighted and Intravoxel Incoherent Motion Imaging in Evaluation of Prognostic Factors for Rectal Adenocarcinoma

ObjectivesTo analyze the value of amide proton transfer (APT) weighted and intravoxel incoherent motion (IVIM) imaging in evaluation of prognostic factors for rectal adenocarcinoma, compared with diffusion weighted imaging (DWI).Materials and MethodsPreoperative pelvic MRI data of 110 patients with surgical pathologically confirmed diagnosis of rectal adenocarcinoma were retrospectively evaluated. All patients underwent high-resolution T2-weighted imaging (T2WI), APT, IVIM, and DWI. Parameters including APT signal intensity (APT SI), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), and apparent diffusion coefficient (ADC) were measured in different histopathologic types, grades, stages, and structure invasion statuses. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic efficacy, and the corresponding area under the curves (AUCs) were calculated.ResultsAPT SI, D and ADC values of rectal mucinous adenocarcinoma (MC) were significantly higher than those of rectal common adenocarcinoma (AC) ([3.192 ± 0.661%] vs. [2.333 ± 0.471%], [1.153 ± 0.238×10-3 mm2/s] vs. [0.792 ± 0.173×10-3 mm2/s], and [1.535 ± 0.203×10-3 mm2/s] vs. [0.986 ± 0.124×10-3 mm2/s], respectively; all P<0.001). In AC group, the APT SI and D values showed significant differences between low- and high-grade tumors ([2.226 ± 0.347%] vs. [2.668 ± 0.638%], and [0.842 ± 0.148×10-3 mm2/s] vs. [0.777 ± 0.178×10-3 mm2/s], respectively, both P<0.05). The D value had significant difference between positive and negative extramural vascular invasion (EMVI) tumors ([0.771 ± 0.175×10-3 mm2/s] vs. [0.858 ± 0.151×10-3 mm2/s], P<0.05). No significant difference of APT SI, D, D*, f or ADC was observed in different T stages, N stages, perineural and lymphovascular invasions (all P>0.05). The ROC curves showed that the AUCs of APT SI, D and ADC values for distinguishing MC from AC were 0.921, 0.893 and 0.995, respectively. The AUCs of APT SI and D values in distinguishing low- from high-grade AC were 0.737 and 0.663, respectively. The AUC of the D value for evaluating EMVI involvement was 0.646.ConclusionAPT and IVIM were helpful to assess the prognostic factors related to rectal adenocarcinoma, including histopathological type, tumor grade and the EMVI status.

Predictive Value of the Prognostic Nutritional Index in Neoadjuvant Chemoradiotherapy for Rectal Cancer

Background/Aim: Prognostic nutritional index (PNI) and neutrophil-to-lymphocyte ratio (NLR) indicate nutritional status and host immunity. We used immunohistochemistry and apparent diffusion coefficient (ADC) values calculated using diffusion-weighted imaging (DWI) to investigate relationships of these factors with pathological and radiological characteristics in rectal cancer treated with neoadjuvant chemoradiotherapy (nCRT). Patients and Methods: We evaluated expression levels of VEGFA, CD8, CD33, and ADC values in tumors pre/post nCRT; and analyzed the relationships between those factors and PNI, NLR in 32 patients. Results: Pretreatment PNI negatively correlated with change in tumor stromal CD8+ T cells and positively correlated with ADC values. Pretreatment NLR and PNI change correlated with recurrence-free survival (RFS). Conclusion: Patients with higher pretreatment PNI had greater changes in ADC values and stromal CD8+ T-cell counts, and those with greater PNI reduction from nCRT had a worse prognosis. Proper nutritional management during nCRT benefits patients and may lead to better prognosis in rectal cancer.

Treatment Effect of a Vascular-Disrupting Agent Dynamically Monitored by DWI: An Animal Experimental Study

Objective. To investigate the treatment effect of a vascular-disrupting agent, M410, using diffusion-weighted imaging in a rabbit model of hepatic VX2 tumor. Methods. 28 New Zealand white rabbit models with VX2 liver tumors were established and were randomly divided into M410 (intravenous injection of M410 at a dose of 25 mg/kg every three days) and control (intravenous injection of saline every three days) groups. Conventional and diffusion-weighted imaging (DWI) were acquired on a 3.0 T MR unit at baseline, 4 h, d 1, d 4, d 7, and d 14 posttreatment. B-value with 700 (s/mm2) was chosen during DWI examinations. Tumor volume and apparent diffusion coefficient (ADC) values of the entire tumor and solid component of the tumor at every time point were measured. Two randomly chosen rabbits from each group were sacrificed for H&E staining and CD34 immunohistochemical assessments at each time point. An independent sample t-test was used to assess differences in tumor sizes and ADC values of the entire tumor and solid component of tumors between two groups, with P < 0.05 considered statistically significant. Result. There was no significant difference in tumor volume between the two groups at baseline, 4 h, and d 1. With time, the tumors in the control group grew significantly faster than those in the M410 group, and the average ADC values of the M410 group were lower than those of the control group at d 1 and higher than those of the control group at d 4; as such, there were statistical differences between the two groups at these two time points but not at the other four time points. The following pathological results reflected the underlying morphological changes and vascular alterations. Conclusions. M410 performed well in inhibiting the growth of the hepatic VX2 tumor which could be noninvasively monitored by DWI metrics.

Diagnostic performance of apparent diffusion coefficient values for the differentiation of intrahepatic cholangiocarcinoma from gastrointestinal adenocarcinoma liver metastases

Background We aimed to investigate whether there is a difference between intrahepatic cholangiocarcinoma (IHCC) and liver metastases of gastrointestinal system (GIS) adenocarcinoma in terms of apparent diffusion coefficient (ADC) values. Patients and methods From January 2018 to January 2020, we retrospectively examined 64 consecutive patients with liver metastases due to gastrointestinal system adenocarcinomas and 13 consecutive IHCC in our hospital’s medical records. After exclusions, fifty-three patients with 53 liver metastases and 10 IHCC were included in our study. We divided the patients into two groups as IHCC and liver metastases of GIS adenocarcinoma. For mean apparent diffusion coefficient (ADCmean) values, the region of interests (ROI) was placed in solid portions of the lesions. ADCmean values of groups were compared. Results The mean age of IHCC group was 62.50 ± 13.49 and mean age of metastases group was 61.15 ± 9.18. ADCmean values were significantly higher in the IHCC group compared to the metastatic group (p < 0.001). ROC curves method showed high diagnostic accuracy (AUC = 0.879) with cut-off value of < 1178 x 10-6 mm2/s for ADCmean (Sensitivity = 90.57, Specificity = 70.0, positive predictive value [PPV] = 94.1, negative predictive value [NPV] = 58.3) in differentiating adenocarcinoma metastases from IHCC. Conclusions The present study results suggest that ADC values have a potential role for differentiation between IHCC and GIS adenocarcinoma liver metastases which may be valuable for patient management.

Tuberculoma – a great mimicker: can diffusion tensor imaging and tractography help?

Background Central nervous system (CNS) tuberculomas often mimic tumors on conventional imaging, differentiation of which may not be possible without invasive tissue sampling. Diffusion tensor imaging (DTI), owing to its unrivalled property of characterizing molecular diffusion, may help in better lesion characterization and tractography may help understand the pattern of white matter involvement by tuberculomas. Purpose To estimate qualitative and quantitative diffusion tensor changes in brain tuberculomas and to evaluate patterns of white matter involvement using 3D tractography. Material and Methods Thirty patients with brain tuberculomas were evaluated on a 3-T magnetic resonance scanner. Diffusion tensor images were acquired along 20 non-colinear encoding directions with two b-values (b = 0, b = 1000). Regions of interest (ROIs) were drawn on quantitative fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps in the center of the tuberculoma and perilesional area. Similar ROIs were placed in contralateral hemispheres for comparison. Tractography maps were also generated. Results Mean FA in the center and perilesional area of tuberculomas were 0.098 ± 0.041 and 0.311 ± 0.135, respectively. ADC values in corresponding regions were 0.920 ± 0.272 ×10−3 mm2/s and 1.157 ± 0.277 ×10−3 mm2/s. These values were significantly different compared to contralateral similar brain parenchyma. Tractography revealed interruption of white fibers in the center with deviation of fibers at the periphery in the majority of tuberculomas with none showing infiltration of white matter described in tumors. Conclusion Significant qualitative as well as quantitative DTI changes were seen in tuberculoma and perilesional areas compared to contralateral hemisphere with tractography showing a pattern different from that described in tumors. These findings may help to differentiate tuberculomas from infiltrating tumors.

Gradient nonlinearity correction in liver DWI using motion-compensated diffusion encoding waveforms

Objective To experimentally characterize the effectiveness of a gradient nonlinearity correction method in removing ADC bias for different motion-compensated diffusion encoding waveforms. Methods The diffusion encoding waveforms used were the standard monopolar Stejskal–Tanner pulsed gradient spin echo (pgse) waveform, the symmetric bipolar velocity-compensated waveform (sym-vc), the asymmetric bipolar velocity-compensated waveform (asym-vc) and the asymmetric bipolar partial velocity-compensated waveform (asym-pvc). The effectiveness of the gradient nonlinearity correction method using the spherical harmonic expansion of the gradient coil field was tested with the aforementioned waveforms in a phantom and in four healthy subjects. Results The gradient nonlinearity correction method reduced the ADC bias in the phantom experiments for all used waveforms. The range of the ADC values over a distance of ± 67.2 mm from isocenter reduced from 1.29 × 10–4 to 0.32 × 10–4 mm2/s for pgse, 1.04 × 10–4 to 0.22 × 10–4 mm2/s for sym-vc, 1.22 × 10–4 to 0.24 × 10–4 mm2/s for asym-vc and 1.07 × 10–4 to 0.11 × 10–4 mm2/s for asym-pvc. The in vivo results showed that ADC overestimation due to motion or bright vessels can be increased even further by the gradient nonlinearity correction. Conclusion The investigated gradient nonlinearity correction method can be used effectively with various motion-compensated diffusion encoding waveforms. In coronal liver DWI, ADC errors caused by motion and residual vessel signal can be increased even further by the gradient nonlinearity correction.

Diagnostic Accuracy of Multiple MRI Parameters in Dealing With Incidental Thyroid Nodules

Background: Different MRI parameters have been studied for evaluating thyroid nodules. Diffusion-weighted imaging (DWI) and T2 imaging sequences with considerable efficacy in evaluating soft tissue tumors merit further assessment for thyroid nodules investigation.Method: In this study, patients with thyroid nodules indicative of fine-needle aspiration and cytology (FNAC) underwent MR imaging studies. The T2 signal intensity(SI), T2 signal intensity ratio (SIR), Z value, and apparent diffusion coefficient (ADC) values of the thyroid nodule were obtained for every patient. Regarding the FNAC results, the nodules were divided into malignant and benign groups. The two groups' MRI parameters were compared using a two samples independent t-test and the cut-off values estimated by analyzing the receiver operating characteristics plot.Results: The T2 values, SIR, Z values, and ADC values were significantly higher in the benign group than malignant. The cut-off points of 230 (AUC= 0.759), 3.38 (AUC=0.754), 37(AUC=0.759), and 1.73(AUC=.690) were obtained for T2values, SIR, Z value, and ADC values, respectively.Conclusion: T2 values, SIR, Z values, and ADC values are reliable parameters in discriminating benign from malignant thyroid nodules, and cut-off points of 230, 3.38, 37, and 1.73 could be reliable cut-off points for each parameter, respectively. However, further studies with a larger sample size are needed to confirm these findings.