Contrast enhanced MR imaging of female pelvic cancers: Established methods and emerging applications

Whole solid tumor volume histogram parameters for predicting the recurrence in patients with epithelial ovarian carcinoma: a feasibility study on quantitative DCE-MRI

BACKGROUND

Preoperative prediction of the recurrence of epithelial ovarian carcinoma (EOC) can guide the clinical treatment and improve the prognosis. However, there are still no reliable predictive biomarkers.

PURPOSE

To evaluate whether whole solid tumor volume histogram parameters measured from quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can predict the recurrence in patients with EOC.

MATERIAL AND METHODS

We followed up 56 patients with surgical and histopathologically diagnosed EOC who underwent quantitative DCE-MRI scans. The differences of the histogram parameters between patients with and without recurrence were compared. Mann-Whitney U test, Pearson's Chi-squared test, or Fisher's exact test, and receiver operating characteristic (ROC) curves were used for statistical analysis.

RESULTS

All histogram parameters of K^trans, k_ep, and v_e were not significantly different between EOC patients with and without recurrence (P>0.05). For 30 patients with high-grade serous ovarian carcinoma (HGSOC), the histogram parameters of K^trans (mean and 5th, 10th, 25th, 50th, 75th percentiles) and k_ep (mean and 50th percentile) in 12 patients with recurrence were significantly lower than those in 18 patients without recurrence (all P<0.05). ROC curves showed that the 5th percentile of K^trans had the largest area under the curve (AUC) of 0.792 for predicting the recurrence in patients with HGSOC. When the threshold value was ≤0.0263/min, the sensitivity, specificity, and accuracy were 100%, 66.7%, and 80%, respectively.

CONCLUSION

Instead of predicting the recurrence of EOC, whole solid tumor volume quantitative DCE-MRI histogram parameters could predict the recurrence of HGSOC and may be potential biomarkers for the prediction of HGSOC recurrence.

Advances in MR Imaging of the Female Pelvis

This article focuses on advanced MR imaging techniques of the female pelvis and clinical applications for benign and malignant disease. General and abbreviated protocols for female pelvic MR imaging are reviewed. Diffusion-weighted imaging, dynamic contrast-enhanced MR imaging, and susceptibility-weighted imaging are discussed in the context of adnexal mass characterization using the ADNEx-MR scoring system, evaluation of endometriosis, local staging of cervical and endometrial cancers, assessment of nodal and peritoneal metastasis, and potential detection of leiomyosarcoma. MR defecography is also discussed regarding evaluation of multicompartmental pelvic floor disorders.

Asymptomatic Bartholin Cyst: Evaluation With Multidetector Row Computed Tomography

OBJECTIVE

The aim of this study was to determine the frequency, morphology, and attenuation characteristics of Bartholin cysts on multidetector computed tomography (MDCT) in asymptomatic women.

METHODS

A total of 3280 consecutive MDCT examinations were assessed for Bartholin cysts. The diagnosis was based on shape, contrast enhancement, and anatomical location. Age, laterality, size, and attenuation patterns were recorded. Scans from patients with paravaginal-related symptoms were excluded, and any available follow-up MDCT scans or magnetic resonance images were evaluated.

RESULTS

Asymptomatic Bartholin cysts were seen in 17 patients (0.52%) (mean age, 56 years). The mean maximum cyst diameter was 21.8 mm. High-attenuation cysts comprised 47% of cases, all in older (≥50 years) patients. Follow-up MDCT scans showed minimal changes over time.

CONCLUSIONS

High-attenuation Bartholin cysts are more common than previously thought and are usually seen in older women. The size and attenuation of Bartholin cysts show only minimal changes over time.

PET/CT and MRI in the imaging assessment of cervical cancer

Imaging plays a central role in the evaluation of patients with cervical cancer and helps guide treatment decisions. The purpose of this pictorial review is to describe magnetic resonance (MR) imaging and positron emission tomography (PET)/computed tomography (CT) assessment of cervical cancer, including indications for imaging, important findings that may result in management change, as well as limitations of both modalities. The International Federation of Gynecology and Obstetrics cervical cancer staging system does not officially include imaging; however, the organization endorses the use of MR imaging and PET/CT in the management of patients with cervical cancer where these modalities are available. MR imaging provides the best visualization of the primary tumor and extent of soft tissue disease. PET/CT is recommended for assessment of nodal involvement, as well as distant metastases. Both MR imaging and PET/CT are used to follow patients post-treatment to assess for recurrence. This review focuses on the current MR imaging and PET/CT protocols, the utility of these modalities in assessing primary tumors and recurrences, with emphasis on imaging findings which change management and on imaging pitfalls to avoid. It is important to be familiar with the MR imaging and PET/CT appearance of the primary tumor and metastasis, as well as the imaging pitfalls, so that an accurate assessment of disease burden is made prior to treatment.

Diffusion-weighted imaging and dynamic contrast-enhanced MRI in assessing response and recurrent disease in gynaecological malignancies

Magnetic resonance imaging (MRI) has an established role in imaging pelvic gynaecological malignancies. It is routinely used in staging endometrial and cervical cancer, characterizing adnexal masses, selecting optimal treatment, monitoring treatment and detecting recurrent disease. MRI has also been shown to have an excellent performance and an evolving role in surveillance of patients after chemoradiotherapy in cervical cancer, post-trachelectomy, detecting early recurrence and planning exenterative surgery in isolated central recurrences in both cervical and endometrial cancer and in young patients on surveillance for medically managed endometrial cancer. However, conventional MRI still has limitations when the morphological appearance of early recurrent or residual disease overlaps with normal pelvic anatomy or treatment effects in the pelvis. In particular, after chemoradiotherapy for cervical cancer, distinguishing between radiotherapy changes and residual or early recurrent disease within the cervix or the vaginal vault can be challenging on conventional MRI alone. Therefore, there is an emerging need for functional imaging to overcome these limitations. The purpose of this paper is to discuss the emerging functional MRI techniques and their applications in predicting treatment response, detecting residual disease and early recurrent disease to optimize the treatment options available using diffusion-weighted imaging and dynamic contrast enhancement particularly in cervical and endometrial cancer.

Imaging of Tumor Angiogenesis for Radiologists--Part 2: Clinical Utility

Angiogenesis is a key cancer hallmark involved in tumor growth and metastasis development. Angiogenesis and tumor microenvironment significantly influence the response of tumors to therapies. Imaging techniques have changed our understanding of the process of angiogenesis, the resulting vascular performance, and the tumor microenvironment. This article reviews the status and potential clinical value of the imaging modalities used to assess the status of tumor vasculature in vivo, before, during, and after treatment.

Endometrial cancer: diagnostic value of quantitative measurements of microvascular changes with DCE-MR imaging

OBJECT

To assess the diagnostic value of dynamic contrast-enhanced (DCE) perfusion-magnetic resonance imaging (MRI) in detection, characterization and grading of endometrial cancer, using histopathological analysis as the standard of reference.

MATERIALS AND METHODS

Eighty patients with histologically proven endometrial carcinoma who underwent MRI (1.5 T magnet) of the pelvis for staging purposes were enrolled in the study. Each MR examination consisted of multiplanar T2 and T1-weighted turbo spin echo (TSE) sequences and T1-weighted gradient echo sequences before, during and after the administration of contrast medium. For each patient colour perfusion maps were derived from the dynamic sequences using a dedicated workstation. On the maps a region of interest was manually drawn both on normal myometrium and on the endometrial lesion. Then the following perfusion parameters were automatically calculated: relative enhancement (RE, %), maximum enhancement (ME, %), maximum relative enhancement (MRE, %) and time to peak (TTP, s).

RESULTS

All patients underwent total hysterectomy. Histopathological analysis documented: G1 tumour in 21 patients, G2 tumour in 44 patients, G3 tumour in 14 patients and one squamous cell carcinoma. The following mean value perfusion parameters, with corresponding mean standard deviation, were obtained for endometrial cancer: RE (%) = 59.3 ± 36.3; ME (%) = 862.7 ± 475.9; MRE (%) = 75.3 ± 37.6 and TTP (s) = 164.7 ± 78. RE, ME and MRE were lower in tumour lesions than in normal myometrium (p < 0.001) and significantly higher values (p < 0.001) of perfusion parameters were obtained for G1 (well-differentiated) tumours as compared to those in G2 and G3 (moderately and poorly differentiated) lesions.

CONCLUSION

DCE perfusion-MRI can provide quantitative information on tissue vascularity, which may be of help in detecting endometrial cancer and in the assessment of tumour grading.

Semiquantitative perfusion combined with diffusion-weighted MR imaging in pre-operative evaluation of endometrial carcinoma: results in a group of 57 patients

PURPOSE

To evaluate the semiquantitative DCE and quantitative DWI parameters in endometrial cancer, in order to assess the presence of neoplastic tissue and normal myometrium and to ascertain a potential relationship with tumor grade.

METHODS AND MATERIALS

A total of 57 patients with biopsy-proven endometrial adenocarcinoma who underwent MR imaging examination for staging purposes were retrospectively evaluated. Imaging protocol included multiplanar T1- and T2-weighted TSE, DCE T1-weighted (THRIVE; 0, 30, 90 and 120seconds after intravenous injection of gadolinium) and DWIBS sequences (b values=0 and 1000mm(2)/s). Color perfusion and ADC maps were automatically generated on dedicated software. Relative enhancement (RE, %), maximum enhancement (ME, %), maximum relative enhancement (MRE, %), time to peak (TTP, s) and mean apparent diffusion coefficient (ADC) were calculated by manually drawing a region of interest (ROI) both on the neoplastic tissue and the normal myometrium. Histopathology was used as reference standard.

RESULTS

Histopathological analysis confirmed the presence of endometrial carcinoma in all patients. Neoplastic tissue demonstrated significantly lower (P<0.001) values of RE (%) 63.92±35.68; ME (%) 864.91±429.54 and MRE (%) 75.97±38.26 as compared to normal myometrium (RE (%) 151.43±55.99; ME (%) 1800.73±721.32; MRE (%) 158.28±54.05). TTP was significantly higher (P<0.05) in tumor lesion (385.51±1630.27 vs 195.44±78.69). Mean ADC value of neoplastic tissue (775.09±?220.73×10(-3)mm(2)/s) was significantly lower (P<0.05) than in myometrium (1602.37±378.54×10(-3)mm(2)/s). The analysis of perfusion and diffusion parameters classified according to tumor grades, showed a statistically significant difference only for RE (P=0.043) and ME (P=0.007).

CONCLUSIONS

Perfusion parameters and mean ADC differ significantly between endometrial cancer and normal myometrium, potentially reflecting the different microscopical features of cellularity and vascularity; however a significant relationship with tumor grade was not found in our series.

Establishment of a lung metastatic breast tumor xenograft model in nude rats

Objective

Larger animal models provide relevant tumor burden in the development of advanced clinical imaging methods for non-invasive cancer detection and diagnosis, and are especially valuable for studying metastatic disease. Most available experimental models, however, are based on immune-compromised mice. To lay the foundation for studying spontaneous metastasis using non-invasive magnetic resonance imaging (MRI), this study aims to establish a highly metastatic breast cancer xenograft model in nude rats.

Materials and Methods

A highly metastatic variant of human adenocarcinoma MDA-MB-231 known as LM2 was inoculated into nude rats. Orthotopic and subcutaneous (flank) sites were compared, with half of the orthotopic injections guided by ultrasound imaging. MRI with gadolinium contrast administration was performed weekly beginning on Day 6 and ending on Day 104. Excised tumors were assessed on histology using hematoxylin and eosin and CD34. Fisher's exact test was used to compare successful tumor induction amongst different inoculation methods.

Results

Primary LM2 tumors were established orthotopically in all cases under ultrasound-guided injection, and none otherwise (p = 0.0028). Contrast-enhanced MRI revealed rapidly progressing tumors that reached critical size (15 mm diameter) in 2 to 3 weeks after inoculation. MRI and histology findings were consistent: LM2 tumors were characterized by low vascularity confined to the tumor rim and large necrotic cores with increasing interstitial fluid pressure.

Conclusions

The metastatic LM2 breast tumor model was successfully established in the mammary fat pads of nude rats, using ultrasound needle guidance as a non-invasive alternative to surgery. This platform lays the foundation for future development and application of MRI to study spontaneous metastasis and different stages throughout the metastatic cascade.

Gadolinium-free extracellular MR contrast agent for tumor imaging

PURPOSE

To evaluate a new formulation of manganese porphyrin as a potential gadolinium (Gd)-free extracellular magnetic resonance imaging (MRI) contrast agent for dynamic contrast-enhanced (DCE) MRI of tumors.

MATERIALS AND METHODS

A previously reported new contrast agent, MnTCP, was evaluated in six female tumor-bearing nude rats. MRI was performed on a 3 T clinical scanner 3 to 4 weeks after inoculation of breast tumor cells in the mammary fat pads. Gd-DTPA was injected intravenously, followed by injection of MnTCP at least 2 hours later (both at 0.05 mmol/kg). T1 relaxation time measurements and DCE-MRI were performed.

RESULTS

Enhancement and clearance patterns were visually similar between MnTCP and Gd-DTPA. However, relative R1 increases in all 11 tumors were larger for MnTCP over 60 minutes postcontrast, the difference being significant as late as 20 minutes (R1post /R1pre  = 1.42 ± 0.15 for MnTCP vs. 1.20 ± 0.08 for Gd-DTPA, P < 0.05). R1 -related effects for MnTCP were largely reduced after 60 minutes (R1post /R1pre  = 1.13 ± 0.07) and completely gone within 24 hours (R1post /R1pre  = 0.97 ± 0.06). DCE-MRI revealed a consistently larger (1.5 to over 2-fold) peak enhancement and higher values of the steepest slope, time-to-peak, and AUC60 in all tumors with MnTCP (P < 0.01).

CONCLUSION

MnTCP is an alternative to extracellular Gd agents for tumor imaging, offering sensitive detection and rapid renal clearance.

Gadolinium-free T1 contrast agents for MRI: tunable pharmacokinetics of a new class of manganese porphyrins

PURPOSE

To evaluate a new class of manganese porphyrins with tunable pharmacokinetics as potential gadolinium (Gd)-free T1 agents for contrast-enhanced magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Two new contrast agents, MnTCP and MnP2, were evaluated in four female rats. MRI was performed daily up to 3 days postinjection (0.05 mmol/kg) on a 3 T clinical scanner. T1 relaxation times and dynamic contrast-enhanced MRI were performed to assess contrast enhancement and clearance in blood, heart, liver, kidney, and muscle.

RESULTS

Relative T1 decreases were similar for MnTCP and Gd-DTPA in all tissues but were significantly larger (P < 0.05) for MnP2 in blood, heart, kidney, and liver (2-6-fold larger). Clearance of MnTCP was similar to Gd-DTPA, with T1 returning to baseline by 40 minutes and complete elimination in 1 day. MnP2 was cleared from blood after 2 days and sustained a lowered T1 in other tissues for at least 1 hour (P < 0.05). The maximum enhancement, slope, and time-to-peak were similar between contrast agents. Only the parameter AUC60 differed, with MnP2 yielding the largest AUC60 values primarily through longer retention in tissue.

CONCLUSION

MnTCP and MnP2 offer distinct applications as Gd-free T1 contrast agents. MnTCP behaves like a Gd-DTPA analog, while MnP2 provides significantly greater and longer positive signal enhancement.

Assessment of wall inflammation and fibrosis in Crohn's disease: value of T1-weighted gadolinium-enhanced MR imaging

MRI is increasingly advocated as a robust method for quantifying disease activity in Crohn's disease. In particular, T1-weighted gadolinium-enhanced imaging shows considerable promise as a marker of inflammatory activity. However, interpretation of the literature must be made with an understanding of (i) the technical limitations of T1-weighted acquisition protocols and enhancement measurements; (ii) differences in standards of reference for disease activity employed between published studies; and (iii) important underlying macro and micro vascular changes in Crohn's disease. This review will focus specifically on the value of T1-weighted gadolinium-enhanced imaging in the assessment of wall inflammation and fibrosis.