MRI is increasingly advocated as an optimal method of staging rectal cancer. The technique enables depiction of the relationship of tumour to the mesorectal fascia and may thus identify tumours at risk of positive circumferential margin involvement at surgery. Depth of extramural spread may also be accurately measured and tumour deposits within the mesorectum are shown. It is important that a high spatial resolution technique is used in order to accurately depict these features and care should be taken in ensuring that images acquired cover the entire rectal tumour and mesorectum. This paper describes the technique of high spatial resolution rectal cancer imaging and the potential technical pitfalls in acquiring good quality images. Important factors to consider include: adequate scan duration to achieve high spatial resolution images with sufficient signal to noise ratio, careful positioning of the pelvic phased array coil, use of T2 weighted turbo spin-echo rather than T1 weighted imaging and careful planning of scans to ensure that images are obtained perpendicular to the rectal wall.

No abstract

This paper describes the spectrum of imaging features of oesophageal adenocarcinoma seen using high-resolution T2-weighted (T2W) magnetic resonance imaging (MRI). Thirty-nine patients with biopsy-proven oesophageal adenocarcinoma were scanned using an external surface coil. A sagittal T2W sequence was used to localise the tumour and to plan axial images perpendicular to the tumour. Fast spin-echo (FSE) T2W axial sequence parameters were: TR/TE, 3,300-5,000 ms/120-80 ms; field of view (FOV) 225 mm, matrix 176x512(reconstructed) mm to 256x224 mm, giving an in-plane resolution of between 1.28x0.44 mm and 0.88x1.00 mm, with 3-mm slice thickness. Thirty-three patients underwent resection and the MR images were compared with the histological whole-mount sections. There were four T1, 12 T2, and 17 T3 tumours. The T2W high-resolution MRI sequences produced detailed images of the oesophageal wall and surrounding structures. Analysis of the imaging appearances for different tumour T stages enabled the development of imaging criteria for local staging of oesophageal cancer using high-resolution MRI. Our study illustrates the spectrum of appearances of oesophageal cancer on T2W high-resolution MRI, and using the criteria established in this study, demonstrates the potential of this technique as an alternative non-invasive method for local staging for oesophageal cancer.

Purpose: To evaluate intrinsic susceptibility (IS) MRI for the identification of cycling hypoxia, and the assessment of its extent and spatial distribution, in head and neck squamous cell carcinoma (HNSCC) xenografts and patients.Experimental Design: Quantitation of the transverse relaxation rate, R 2 Ã , which is sensitive to paramagnetic deoxyhemoglobin, using serial IS-MRI acquisitions, was used to monitor temporal oscillations in levels of paramagnetic deoxyhemoglobin in human CAL R xenografts and patients with HNSCC at 3T. Autocovariance and power spectrum analysis of variations in R 2 Ã was performed for each imaged voxel, to assess statistical significance and frequencies of cycling changes in tumor blood oxygenation. Pathologic correlates with tumor perfusion (Hoechst 33342), hypoxia (pimonidazole), and vascular density (CD31) were sought in the xenografts, and dynamic contrast-enhanced (DCE) MRI was used to assess patient tumor vascularization. The prevalence of fluctuations within patient tumors, DCE parameters, and treatment outcome were reported.Results: Spontaneous R 2 Ã fluctuations with a median periodicity of 15 minutes were detected in both xenografts and patient tumors. Spatially, these fluctuations were predominantly associated with regions of heterogeneous perfusion and hypoxia in the