A prospective comparative dosimetric study between diffusion weighted MRI (DWI) & T2-weighted MRI (T2W) for target delineation and planning in cervical cancer brachytherapy

Associations between ADC histogram analysis values and tumor-micro milieu in uterine cervical cancer

BACKGROUND

The complex interactions of the tumor micromilieu may be reflected by diffusion-weighted imaging (DWI) derived from the magnetic resonance imaging (MRI). The present study investigated the association between apparent diffusion coefficient (ADC) values and histopathologic features in uterine cervical cancer.

METHODS

In this retrospective study, prebiopsy MRI was used to analyze histogram ADC-parameters. The biopsy specimens were stained for Ki-67, E-cadherin, vimentin and tumor-infiltrating lymphocytes (TIL, all CD45 positive cells). Tumor-stroma ratio (TSR) was calculated on routine H&E specimens. Spearman's correlation analysis and receiver-operating characteristics curves were used as statistical analyses.

RESULTS

The patient sample comprised 70 female patients (age range 32-79 years; mean age 55.4 years) with squamous cell cervical carcinoma. The interreader agreement was high ranging from intraclass coefficient (ICC) = 0.71 for entropy to ICC = 0.96 for ADCmedian. Several ADC-histogram parameters correlated strongly with the TSR. The highest correlation coefficient achieved p10 (r = -0.81, p < 0.0001). ADCmean can predict tumors with high TSR, AUC: 0.91, sensitivity: 0.91 (95% CI 0.77;0.96), specificity: 0.91 (95% CI 0.78;0.97). Several ADC-histogram parameters correlated slightly with the proliferation index Ki-67. No associations were found with TIL, E-Cadherin and vimentin. In well and moderately differentiated cancers, ADC histogram values showed stronger correlations with Ki-67 and TSR than in poorly differentiated tumors.

CONCLUSION

ADC values are strongly associated with tumor-stroma ratio. The ADC mean can be used to predict tumors with high TSR. Associations between histopathology and ADC values depend on tumor differentiation. ADC values show only weak associations with Ki-67 and none with TIL, vimentin and E-cadherin.

Functional Magnetic Resonance Imaging in Cervical Cancer Diagnosis and Treatment

Cervical Cancer is the fourth most common cancer in women worldwide. Treatment with chemoradiotherapy followed by brachytherapy achieves high local control, but recurrence with metastatic disease impacts survival. This highlights the need for predictive and prognostic biomarkers identifying populations at risk of poorer treatment response and survival. Magnetic resonance imaging (MRI) is routinely used in cervical cancer and is a potential source for biomarkers. Functional MRI (fMRI) can characterise tumour beyond anatomical MRI, which is limited to the assessment of morphology. This review summarises fMRI techniques used in cervical cancer and examines the role of fMRI parameters as predictive or prognostic biomarkers. Different techniques characterise different tumour factors, which helps to explain the variation in patient outcomes. These can impact simultaneously on outcomes, making biomarker identification challenging. Most studies are small, focussing on single MRI techniques, which raises the need to investigate combined fMRI approaches for a more holistic characterisation of tumour.

Utilization of functional MRI in the diagnosis and management of cervical cancer

Introduction

Imaging is integral part of cervical cancer management. Currently, MRI is used for staging, follow up and image guided adaptive brachytherapy. The ongoing IQ-EMBRACE sub-study is evaluating the use of MRI for functional imaging to aid in the assessment of hypoxia, metabolism, hemodynamics and tissue structure. This study reviews the current and potential future utilization of functional MRI imaging in diagnosis and management of cervical cancer.

Methods

We searched PubMed for articles characterizing the uses of functional MRI (fMRI) for cervical cancer. The current literature regarding these techniques in diagnosis and outcomes for cervical cancer were then reviewed.

Results

The most used fMRI techniques identified for use in cervical cancer include diffusion weighted imaging (DWI) and dynamic contrast enhancement (DCE). DCE-MRI indirectly reflects tumor perfusion and hypoxia. This has been utilized to either characterize a functional risk volume of tumor with low perfusion or to characterize at-risk tumor voxels by analyzing signal intensity both pre-treatment and during treatment. DCE imaging in these situations has been associated with local control and disease-free survival and may have predictive/prognostic significance, however this has not yet been clinically validated. DWI allows for creation of ADC maps, that assists with diagnosis of local malignancy or nodal disease with high sensitivity and specificity. DWI findings have also been correlated with local control and overall survival in patients with an incomplete response after definitive chemoradiotherapy and thus may assist with post-treatment follow up. Other imaging techniques used in some instances are MR-spectroscopy and perfusion weighted imaging. T2-weighted imaging remains the standard technique used for diagnosis and radiation treatment planning. In many instances, it is unclear what additional information functional-MRI techniques provide compared to standard MRI imaging.

Conclusions

Functional MRI provides potential for improved diagnosis, prediction of treatment response and prognostication in cervical cancer. Specific sequences such as DCE, DWI and ADC need to be validated in a large prospective setting prior to widespread use. The ongoing IQ-EMBRACE study will provide important clinical information regarding these imaging modalities.

Novel monodisperse FePt nanocomposites for T2-weighted magnetic resonance imaging: biomedical theranostics applications

Given the high incidence and mortality of cancer, current research is focused on designing efficient diagnostic methods. At present, clinical diagnoses are made based on X-ray, computed tomography, magnetic resonance imaging (MRI), ultrasound, and fiber optic endoscopy. MRI is a powerful diagnostic tool because it is non-invasive, has a high spatial resolution, uses non-ionizing radiation, and has good soft-tissue contrast. However, the long relaxation time of water protons may result in the inability to distinguish different tissues. To overcome this drawback of MRI, magnetic resonance contrast agents can enhance the contrast, improve the sensitivity of MRI-based diagnoses, increase the success rate of surgery, and reduce tumor recurrence. This review focuses on using iron-platinum (FePt) nanoparticles (NPs) in T2-weighted MRI to detect tumor location based on dark-field changes. In addition, existing methods for optimizing and improving FePt NPs are reviewed, and the MRI applications of FePt NPs are discussed. FePT NPs are expected to strengthen MRI resolution, thereby helping to inhibit tumor development.