Diffusion weighted imaging of female pelvic cancers: Concepts and clinical applications

Early applications of diffusion weighted magnetic resonance imaging (DWI) were limited to neuroimaging, concentrating either on stroke or brain tumours. With recent advances in MRI hardware and software DWI is now increasingly being investigated for cancer assessment throughout the body.Clinical applications of DWI relating to female pelvic cancers have largely concentrated on detection, localisation and staging of disease. More recently investigators have started to evaluate the ability of DWI for determining tumour histology and even predicting the outcome of chemoradiation treatment.This article reviews the physical concepts of MR diffusion weighting, illustrates the biophysical basis of diffusion contrast and reports the clinical applications of DWI for cervical, endometrial, ovarian, rectal and bladder tumours.     

Tumoren des weiblichen Beckens

Cervical, endometrial and ovarian carcinomas are the main malignant neoplasms of the female pelvis. For CT, a thin-slice venous phase with good bowel contrast is used. For MRI, an anti-peristaltic agent is necessary. Thin-slice T2- weighted TSE images with a high in-plane spatial resolution are particularly suitable for imaging the uterine wall; a parenteral contrast medium is absolutely necessary to demonstrate endometrial and ovarian carcinoma. In the guidelines, MRI is recommended only for cervical cancer FIGO 1b and higher stages; nevertheless, CT and MRI play an important role in preoperative diagnosis of these tumors. Lymph node staging is performed during surgery where possible. In patients with endometrial carcinoma, preoperative staging focuses on the infiltration depth in the myometrium. Preoperative diagnosis of ovarian cancer centers on any tumor spread in the abdomen, and diagnostic imaging methods are designed to provide the surgeon with information about compartments of a possible peritoneal carcinosis that are difficult to see. In patients with incidental findings of ovarian masses, CT and MRI can detect evidence of malignancy, although an exact differential diagnosis is not usually possible in this very heterogeneous group of ovarian tumors.     

Role of diffusion-weighted imaging in the diagnosis of gynecological diseases

Recent technical advances in diffusion-weighted imaging (DWI) greatly enhanced the clinical value of magnetic resonance imaging (MRI) of the body. DWI can provide excellent tissue contrast based on molecular diffusion and may be able to demonstrate malignant tumors. Quantitative measurement of the apparent diffusion coefficient (ADC) may be valuable in distinguishing between malignant and benign lesions. We reviewed DWI and conventional MRI of the female pelvis to study the utility of DWI in patients with gynecological diseases. Although the ADC can help to differentiate between normal and cancerous tissue in the uterine cervix and endometrium, its utility may be limited by the large overlap of the uterine myometrium and ovaries. On the other hand, the ADC may be useful for monitoring the therapeutic outcome after uterine arterial embolizati (UAE), chemotherapy and/or radiation therapy. In patients with ovarian cancer, DWI demonstrates high intensity not only at the primary cancer site but also in disseminated peritoneal implants. When added to conventional MRI findings, DWI and ADC values provide additional information and DWI may play an important role in the diagnosis of patients with gynecological diseases.     

Genitourinary applications of diffusion-weighted MR imaging in the pelvis

Diffusion-weighted (DW) magnetic resonance (MR) imaging has a large number of potential clinical applications in the female and male pelvis and can easily be added to any routine MR protocol. In the female pelvis, DW imaging allows improvement of staging in endometrial and cervical cancer, especially in locally advanced disease and in patients in whom contrast medium administration should be avoided. It can also be helpful in characterizing complex adnexal masses and in depicting recurrent tumor after treatment of various gynecologic malignancies. DW imaging shows promising results in monitoring treatment response in patients undergoing radiation therapy of cervical cancer. An increase in apparent diffusion coefficient (ADC) values of responders precedes changes in size and may therefore allow early assessment of treatment success. In the male pelvis, the detection of prostate cancer in the peripheral zone is relatively easier than in the central gland based on the underlying ADC values, whereas overlapping values reported in the central gland still need further research. DW imaging might also be applied in the noninvasive evaluation of bladder cancer to differentiate between superficial and muscle-invasive tumors. Initial promising results have been reported in differentiating benign from malignant pelvic lymph nodes based on the ADC values; however, larger-scale studies will be needed to allow the detection of lymph node metastases in an individual patient. Prerequisites for successfully performing DW imaging of the female and male pelvis are standardization of the DW imaging technique, including the choice of b values, administration of an antiperistaltic drug, and comparison of DW findings with those of morphologic MR imaging.     

Diagnostic interplay of proton magnetic resonance spectroscopy and diffusion weighted images with apparent diffusion coefficient values in suspicious breast lesions

Aim of the work

To study the diagnostic performance of combined single voxel 1H-MRS and DW-MRI with ADC values as a non-contrast diagnostic tool, compared to the DCE-MRI, in suspicious breast lesions.

Bildgebende Diagnostik im Staging gynäkologischer Karzinome

The prognosis in patients with gynecologic cancers depends not only on the stage but also on a wide spectrum of other findings. Cross-sectional imaging modalities, including sonography, CT and MRI, have increasingly been used for optimal treatment planning in gynecologic cancers. Their staging criteria are based on the well-established FIGO staging system. CT and MRI compete with sonography, which plays a pivotal role in the evaluation of the female pelvis. This paper reviews the role of sonography, CT and MRI in the staging of gynecologic malignancies. It puts the emphasis on MRI, which has been established as imaging modality of choice in the preoperative evaluation of cervical and endometrial cancer, and which seems slightly superior to CT in the staging of ovarian cancer.     

Can dynamic contrast enhanced magnetic resonance imaging change treatment planning in endometrial carcinoma?

Purpose

To detect the diagnostic accuracy of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) in the assessment of myometrium and cervix infiltration and lymph node (L.N) status in patients with endometrial carcinoma.

Patients and methods

Forty patients with pathologically proven endometrial carcinoma underwent preoperative MRI assessment in the National Cancer Institute, Cairo University, Egypt over three years from 2009 to 2012. Every case had one stage for the T2 weighted images (T2 WIs) alone and another stage for the combined T2 and DCE images according to the revised international federation of gynecology and obstetrics (FIGO) classification. The pathological findings after surgery were the reference standard.

Results

The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of T2 WIs in detection of deep myometrial invasion were 80%, 72%, 70%, 84% and 79%, respectively and 87%, 90%, 85%, 92% and 87%, respectively for DCE-MRI. For cervical infiltration, T2 WIs showed 78.5%, 88%, 73%, 90.5% and 82.5%, respectively while DCE-MRI showed 92%, 97%, 92%, 97% and 95%, respectively. T2 WIs and DCE-MRI had 100% sensitivity and 85% specificity for the detection of L.N metastasis.

Conclusion

DCE-MRI can accurately detect invasion of the myometrium and cervix in cases of endometrial carcinoma.     

MR imaging of the female pelvic region.

Magnetic resonance (MR) imaging is a valuable technique for noninvasive evaluation of the female pelvic region. This article presents the normal anatomy and abnormalities of the female pelvis. MR imaging may be more useful than clinical evaluation or other imaging modalities in diagnosing or staging developmental anomalies, leiomyomas, adenomyosis, endometrial or cervical carcinoma, vaginal neoplasms, ovarian cysts, endometriosis, teratomas, polycystic ovaries, or other ovarian masses. It could potentially replace laparoscopy as a more useful tool in the diagnosis of uterine anomalies. MR imaging is generally capable of helping determine whether a pelvic mass is uterine or adnexal in origin and may be used to characterize some adnexal masses. In some cases, MR imaging is used to differentiate recurrent disease from posttreatment fibrosis, which aids in treatment planning.     

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

Contrast enhanced magnetic resonance imaging of female pelvic cancers has been established for over 20 years. Conventional contrast enhanced imaging involves acquiring a set of pre-contrast T1 weighted images, followed by intravenous injection of an gadolinium based contrast agent and subsequent acquisition of a second set of contrast enhanced images. Developments in MR hardware and pulse sequences over the last 10 years have made dynamic contrast enhanced (DCE) protocols possible. DCE-MRI entails imaging of the same volume repeatedly prior to, during and following contrast injection.There have also been developments in image analysis methods and tools to reflect the increased data acquired. Qualitative analysis of contrast enhanced imaging (whether a single set or temporal series) by radiologists remains the mainstay for clinical reporting. Semi-quantitative assessment of signal intensity versus time curves and full pharmacokinetic modelling methods have emerged for evaluation of DCE-MRI data.DCE-MRI has found an established role in the detection, localisation and staging of female pelvic malignancies. Emerging applications of DCE-MRI include assessment of tumour grade, histology prior to and following treatment and prediction of individual and final treatment outcome.This article reviews the biophysical basis of contrast enhancement, the technical aspects of performance and analysis of DCE-MRI studies, and the established and emerging clinical utility of DCE-MRI in female pelvic malignancies.     

Pelvic endometriosis: MR imaging

The value of magnetic resonance (MR) imaging at 0.35 T in detecting, characterizing, and staging pelvic endometriosis was prospectively investigated in 30 consecutive women in whom this disease was clinically suspected. MR findings were correlated with the results of laparoscopy (13 women) and laparotomy (17 women). Surgical examination revealed a normal pelvis in five patients and endometriosis in 25. Three of the five normal cases and 16 of the 25 cases of endometriosis were correctly identified with MR imaging (sensitivity, 64%; specificity, 60%; accuracy, 63%). MR imaging demonstrated seven of eight endometriomas but only 14 of 29 adhesions and only six of 45 endometrial implants. While MR imaging demonstrated endometriomas, ovarian adhesions, and extraperitoneal endometrial implants, it could not accurately depict extraovarian endometrial adhesions and intraperitoneal endometrial implants. In addition, MR imaging findings did not correlate with the surgically determined severity of the disease. These limitations indicate that MR imaging cannot be used as the primary modality in the detection, characterization, and staging of endometriosis; laparoscopy remains the procedure of choice.     

What do we expect from imaging?

The objectives of imaging in gynecologic cancer include tumor detection, tumor diagnosis, staging, and follow-up. In addition, both monitoring response to treatment and differentiating tumor recurrence from post-treatment changes are important indications for imaging. In 2001 it was estimated that there would be 38,300 cases of endometrial cancer, 23,400 cases of ovarian cancer, and 12,900 cases of cervical cancer. This article reviews what information is required by the practicing gynecologist or gynecologic oncologist prior to surgery and briefly summarizes state-of-the-art imaging in answering clinically pertinent questions.     

多模态MRI术前诊断子宫内膜癌分期与分级的价值

目的 分析多模态MRI下子宫内膜癌的影像学特征.方法 经病理组织活检确诊的45例子宫内膜癌患者均进行MRI扫描及后处理分析,包括常规平扫、扩散加权成像(DWI)、动态增强磁共振成像(DCE-MRI)及时间-信号曲线(TIC).结果 DCE-MRI联合DWI的分期确诊率达93.3%,常规MRI为77.8%.肿瘤分化程度与ADC值呈负相关,在G2、G3及G1、G3组间差异显著(P<0.05),在G1、G2组间差异无统计学意义(P>0.05).43例子宫内膜癌TIC呈Ⅰ型及Ⅱ型,2例呈Ⅲ型,正常肌层主要为Ⅲ型,前者TIC各期信号差值(D)、强化率(ER)均低于后者,在>30 s时差异有统计学意义(P<0.05),前者达峰时间(TTP)在 (50±10) s.结论 多模态MRI对子宫内膜癌术前分期与分级的诊断具有重要价值.     

Evaluation of gynecologic malignancy by magnetic resonance imaging.

Currently, MR imaging has demonstrated the greatest accuracy and has potentially the greatest clinical utility for the staging of cervical carcinoma. Endometrial carcinoma also can be staged by MR imaging with reasonable accuracy, although the clinical indications for preoperative endometrial carcinoma staging are less clear. MR imaging has unparalleled capacity for the tissue characterization of adnexal disease and has demonstrated utility for diagnosis of common adnexal masses such as pedunculated leiomyoma, endometrioma, and ovarian dermoid. Its use in the evaluation or staging of ovarian, vaginal, and vulvar carcinoma has not been evaluated fully. MR imaging can demonstrate complications of radiation therapy and surgery and can distinguish most recurrent carcinomas from postradiation fibrosis. New techniques such as arrayed use of surface coils, endoluminal surface coils, fast spin-echo acquisitions, and contrast agents show promise for contributing to the already rapid pace of technologic advancement in the field of MR imaging of the female pelvis.     

Interest of diffusion-weighted echo-planar MR imaging and apparent diffusion coefficient mapping in gynecological malignancies: a review

Magnetic resonance imaging (MRI) remains the standard modality for the local staging of gynecological malignancies but it has several limitations, particularly for lymph node staging or evaluating peritoneal carcinomatosis. Consequently, there has been a growing interest in functional imaging modalities. Based on molecular diffusion, diffusion-weighted imaging (DWI) is a unique, noninvasive modality that provides excellent tissue contrast and was shown to improve the radiological diagnosis of malignant tumors. Using quantitative apparent diffusion coefficient (ADC) measurement of DWI provides a new tool for better distinguishing malignant tissues from benign tumors. The aim of the present review is to report on the results of DWI for the assessment of patients with gynecological malignancies. An analysis of the literature suggests that DWI studies would improve the diagnosis of cervical and endometrial tumors. It may also improve the assessment of tumor extension in patients with peritoneal carcinomatosis from gynecological malignancies. However, since the signal intensity of some cancers can range from high intensity to low intensity, a degree of uncertainty was demonstrated due to the proximity of the normal uterine myometrium and ovaries. Interestingly, there is also evidence that ADC might improve the follow-up and monitoring of patients who receive anticancer therapies, including chemotherapy or radiation therapy.     

Dynamic Contrast-Enhanced Magnetic Resonance Imaging as a Diagnostic Tool in the Assessment of Tumour Angiogenesis in Urinary Bladder Cancer

PurposeThe aim of study is to assess the role of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and correlation with tumour angiogenesis in evaluation of urinary bladder cancer.Material and MethodsThe study included 81 patients with recent presumed diagnosis of bladder tumour or who came for follow up after management of histopathologically proven bladder cancer. All had DCE-MRI with time–signal intensity curve. The radiologic results then correlated with the histopathologic results using both haematoxylin and eosin stain and immuno-histochemical staining for localization and evaluation of CD34 immunoreactivity as a detector for the microvessel density (MVD) and tumour angiogenesis.ResultsSeventy-one cases were pathologically proven to be malignant: 41 cases (58%) showed type III time–signal intensity curve (descending); 22 cases (31%) showed type II (plateau); and 8 cases (11%) showed type I (ascending) curve. The sensitivity of DCE-MRI in stage T1 bladder tumour was 80%; in stage T2, it was (90.9%); and in stage T3, it was (96.9%). Overall accuracy of DCE-MRI in tumour staging was 89.5% and P = .001 (significant). Values more than the cutoff value = 76.13 MVD are cystitis with sensitivity (90%), specificity (91%), and P value is .001, which is statistically highly significant.ConclusionThere is a strong positive association between DCE-MRI (staging and washout slope of the time–signal intensity curve) with histopathologic grade, tumour stage, and MVD in bladder cancer. So, DCE-MRI can be used as reliable technique in preoperative predictions of tumour behavior and affect the planning of antiangiogenetic therapy.     

PET-imaging in tumors of the reproductive trac.

There is increasing evidence that metabolic imaging with positron-emission tomography (PET) using fluor-18 labeled fluorodeoxyglucose (18F FDG) is highly accurate for in vivo detection of a variety of malignancies. This quality gives FDG-PET an important role in the detection of malignant tumors and their metastases as well as for differentiation of tumors of unknown etiology. In the male and female reproductive tract, whole body imaging with FDG-PET is in particular capable of visualizing lymph-node and distant metastases before these changes become apparent on conventional cross-sectional imaging modalities. According to the incidence of tumors in the reproductive tract, FDG-PET-imaging has been evaluated in prostate cancer, ovarian cancer, cervical and testicular cancer. The role of PET is discussed with respect to the current management of patients. The presented data indicate that FDG-PET is more accurate for lymph-node staging in cervical cancer and testicular cancer. In ovarian cancer, FDG-PET may be helpful for detection of tumor recurrence. The role of FDG-PET is questionable in prostate cancer, due to the low metabolic activity of this type of cancer. Carbon-11 labeled acetate and carbon-11 or fluor-18 labeled choline are more promising than FDG for detection of recurrence in prostate cancer. In all other tumors of the reproductive tract there is limited experience with PET for a final conclusion.     

Radiological staging of ovarian cancer: imaging findings and contribution of CT and MRI

Ovarian cancer is the most lethal among the gynecologic malignancies with approximately 70% of patients presenting with advanced tumor stage. The prognosis of patients with ovarian cancer is directly related to the tumor stage and residual tumor burden after cytoreductive surgery. Exploratory laparotomy has been the cornerstone in the management of ovarian cancer, as it offers staging and tumor debulking. Understaging at initial laparotomy, however, is a problem in up to 30%, mainly due to insufficient technique and unexpected peritoneal spread outside the pelvis. Sites difficult to assess intraoperatively including the posterior aspect of the liver and the dome of the diaphragm can be well demonstrated with multiplanar imaging. CT and alternatively MRI have been accepted as adjunct imaging modalities for preoperative staging ovarian cancer. Of these, multidetector CT is the imaging modality of choice for staging ovarian cancer. In a multidisciplinary team approach patient management may be guided towards an individualized treatment plan. The contribution of imaging includes (1) surgery planning including referral practice, (2) selection of candidates for primary chemotherapy by demonstration of non (optimally) resectable disease, and (3) tissue sampling in peritoneal carcinomatosis.     

President’s Address

For imaging of the female pelvis, transvaginal ultrasound is the method of choice. Magnetic resonance imaging and CT provide important additional information in various disorders. Magnetic resonance imaging is superior to CT in diagnosing benign and malignant disorders of the uterus. The same holds for the characterization of adnexal masses, where MR imaging reliably differentiates dermoids, ovarian fibromas, and most endometriomas. Differentiation of other benign and malignant ovarian tumors by CT and MR imaging is based on identical morphological criteria; no superiority of MR imaging over CT has been established. Computed tomography is still the preferred imaging modality for staging ovarian cancer. A thorough knowledge of the pathomorphological changes associated with the different disorders of the female pelvis not only helps to choose the proper imaging modality and examination protocol, but also improves image interpretation.     

Updates in advanced diffusion-weighted magnetic resonance imaging techniques in the evaluation of prostate cancer

Diffusion-weighted magnetic resonance imaging (DW-MRI) is considered part of the standard imaging protocol for the evaluation of patients with prostate cancer. It has been proven valuable as a functional tool for qualitative and quantitative analysis of prostate cancer beyond anatomical MRI sequences such as T2-weighted imaging. This review discusses ongoing controversies in DW-MRI acquisition, including the optimal number of b-values to be used for prostate DWI, and summarizes the current literature on the use of advanced DW-MRI techniques. These include intravoxel incoherent motion imaging, which better accounts for the non-mono-exponential behavior of the apparent diffusion coefficient as a function of b-value and the influence of perfusion at low b-values. Another technique is diffusion kurtosis imaging (DKI). Metrics from DKI reflect excess kurtosis of tissues, representing its deviation from Gaussian diffusion behavior. Preliminary results suggest that DKI findings may have more value than findings from conventional DW-MRI for the assessment of prostate cancer.     

MRI of ovarian masses

MRI provides exquisite views of the pelvic anatomy through its high spatial resolution and tissue contrast, and as such plays a key role in the work up of ovarian lesions, identifying features that distinguish benign and malignant lesions. In the case of primary tumors it enables local staging and detection of metastatic disease to help guide management options such as complex surgery or the consideration of neoadjuvant chemotherapy. Functional MRI techniques such as diffusion‐weighted MRI (DW‐MRI), dynamic contrast‐enhanced MRI (DCE‐MRI) and tumor‐selective molecular imaging are currently being evaluated as possible predictive and prognostic biomarkers in the context of ovarian malignancy, and may play a larger role in routine clinical practice in the future. Herein we provide an overview of the conventional and advanced MRI techniques used to characterize ovarian masses and of the role that MR plays in the staging, treatment selection and follow up of patients with ovarian cancer. J. Magn. Reson. Imaging 2013;37:265–281. © 2012 Wiley Periodicals, Inc.