MRI of the female and male pelvis: current and future applications of contrast enhancement

Pre-operative chemoradiation for non-metastatic locally advanced rectal cancer

BACKGROUND

This review sets out to assess the efficacy of pre-operative chemoradiation when compared to radiotherapy alone before surgery in the treatment of advanced non metastatic rectal surgery.

OBJECTIVES

To determine the efficacy of pre-operative chemoradiation (CRT) compared with radiation (RT) alone, in locally advanced rectal cancer with respect to overall survival, local recurrence and 30 day mortality, sphincter preservation and toxicity of treatment (both acute and late).

SEARCH METHODS

In September 2011, we searched clinical trial registers, the Cochrane Central Register of Controlled Trials, Web of Science, EMBASE and MEDLINE and reviewed reference lists. Further hand searches were conducted of relevant journal proceedings. No language constraints were applied.The following search terms were used: colorectal, rectal, rectum, cancer, carcinoma, tumour, radiotherapy, chemotherapy, chemoradiotherapy, chemoradiation, 5-Fluorouracil, 5-FU, neo-adjuvant, preoperative, surgery, anterior resection, abdominoperineal resection, total mesorectal excision.

SELECTION CRITERIA

Male and female patients aged over 18 years undergoing preoperative chemoradiation or radiotherapy followed by surgery for locally advanced non-metastatic rectal cancer. There was no upper age limit for participants. Locally advanced non-metastatic cancer was defined as stage 3 rectal tumours. These are tumours of any T stage with nodal involvement, without evidence of distant metastases.

DATA COLLECTION AND ANALYSIS

Primary outcome parameters included overall survival and local recurrence rate. Secondary outcome parameters included 30 day mortality, sphincter preservation, pathological response of tumour, acute and late toxicity of treatment. The outcome parameters were summarized using the odds ratio and 95% confidence intervals (CI).

MAIN RESULTS

There were 6 randomised controlled trials eligible for inclusion. A reduction in local recurrence was seen in the CRT group in comparison to the RT group (OR 0.56, 95% CI 0.42-0.75, P<0.0001). The results for overall survival were (OR=1.01 95%CI 0.85-1.20, P=0.88).The 30 day mortality was the same for both groups, CRT vs RT (OR 1.73, 95% CI 0.88-3.38). Sphincter preservation (stoma rate) was also similar for the two interventions (OR 1.02, 95% CI 0.85-1.21, P=0.64). An increase in acute grade 3/4 treatment related toxicity was seen in the CRT group versus the RT group (OR 3.96, 95% CI 3.03, 5.17, P<0.00001), although this result did display heterogeneity P=0.0005. Late toxicity events were similar between the two groups (OR 0.88, 95% CI 0.50, 1.54, P=0.65).

AUTHORS' CONCLUSIONS

RT was compared to the more intensive CRT in the treatment of T3-4, node positive (locally advanced) rectal cancer. While there was no difference in overall survival between RT and CRT, CRT was associated with less local recurrence.

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.

Efficacy of transvaginal contrast-enhanced MRI in the early staging of cervical carcinoma

The objective of this study was to evaluate the efficacy of transvaginal contrast for local staging of cervical carcinoma. Fifty patients diagnosed with cervical carcinoma prospectively underwent magnetic resonance (MR) imaging before and after vaginal opacification (VO) with a mixture of 25 ml saline and 25 ml barium. T2-weighted (T2W) TSE images in axial and sagittal planes were compared before and after vaginal opacification. Dynamic T1W images in sagittal and fat-suppressed T1W images in transverse planes were also evaluated after intravenous contrast administration. Involvement of vaginal wall, lumen, and fornices; parametrium; rectum; and bladder were noted. Changes in local tumor staging and in treatment planning were also assessed after vaginal opacification. MR results were later compared with surgical pathological findings. Twenty-eight patients who went through surgical staging were included in the study. VO did not change any of the MR interpretations in 14 patients (50%). Correct staging was achieved with T2W TSE images with and without VO (in sagittal and transverse planes) in 78.5% and 50% of the patients, respectively. VO correctly lowered staging in seven and increased it in three patients compared with sagittal standard T2W images. Treatment planning was also changed in four (14%) of these patients. When overall accuracy of MR staging to indicate the appropriate treatment was evaluated, patients would have received the proper treatment in 90% and 79% of the cases when only T2W sagittal images with and without VO were evaluated, respectively. Dynamic gradient-echo images in sagittal planes and postcontrast T1W images in transverse planes evaluated with T2W series after VO, accomplished correct staging in 23 (82%) of the patients. MRI staging in early cervical cancer may be difficult and overestimated, especially if the tumor is slightly extended into the proximal vagina. Use of vaginal contrast medium is an easy, well-tolerated, and effective method to better delineate the borders of the tumor. It increases the specificity and accuracy of MR staging by showing the exact relation of the tumor with the vaginal wall and beyond.

Contrast-enhanced magnetic resonance body imaging 5

Many new techniques and applications in magnetic resonance imaging of the body have been introduced in the last decade and, at the same time, a wide variety of contrast media have become available for different imaging strategies. The aim of this article is to review the current use of contrast agents in body MRI. Extracellular and hepatobiliary gadolinium chelates, as well as iron oxide-based contrast media, are discussed and their use in different areas of the body highlighted. Topics to be covered include breast imaging, imaging of the thorax and the mediastinum, and imaging of the upper abdomen, kidneys, and pelvis. Established applications as well as new emerging indications are discussed, and the impact on improved detection and characterization of pathologies is demonstrated.

MR imaging of the bladder

MR imaging of the bladder can now be routinely and easily performed with consistent quality. The latest techniques provide high-resolution images of the soft tissue contrast and the ability to perform dynamic contrast imaging and functional pelvic floor studies. MR imaging fits in as a complimentary tool to cystoscopy and to conventional pelvic floor dynamic studies and can provide a unique imaging perspective of the bladder. It is important, however, to remain cognizant of the limitations of its use in tumor detection and discrimination.

Use of magnetic resonance contrast media in body imaging

A large range of new techniques and applications in magnetic resonance imaging has been introduced in the last decade. Correspondingly, a wide variety of contrast media has become available for different imaging strategies. This article reviews the main indications and techniques in magnetic resonance imaging and magnetic resonance angiography of the body with special regard to contrast media applications and its impact on improved detection and characterization of pathologies in thoracic and abdominal MRI.

Is it necessary to do staging pelvic lymph node dissection for T1c prostate cancer?

The necessity of pelvic lymph node dissection has been questioned in recent years as a result of improved pre-treatment staging based on clinical and pathologic factors. Accurate evaluation of nodal status allows rational selection of therapy and improved outcomes. Nevertheless, lymph node dissection may play a role even in patients with low stage disease (clinical T1c) despite an overall low risk for metastases. Herein we discuss recent advances in the evaluation of lymph nodes in stage T1c prostate cancer with respect to accurate prediction, radiologic imaging, molecular characterization, and operative considerations.