research reports

University of Hull

2004/5

Centre for Magnetic Resonance Investigations
Scientific Director: Professor L W Turnbull

Breast Cancer Program
Dr M. Lowry, Dr P. Gibbs, Dr D. Manton, Ms C. Tan, Mr M. Pickles, Dr M. Sreenivasan, Prof L. Turnbull

The breast cancer research portfolio incorporates both single and multi-centre studies using conventional dynamic contrast-enhanced imaging; single voxel and chemical shift spectroscopic examinations; indirect measurement of tissue oxygenation (1/R2); and automated textural analysis for morphological information to evaluate the therapeutic impact of breast MR scanning. Neoadjuvant chemotherapy for locally advanced breast cancer is used increasing to facilitate conserving surgery and improve prognosis. As changes in tumour patho-physiology preceed reduction in tumour volume, DCE-MRI, single voxel proton MRS and estimation of deoxyhaemoglobin concentrations using 1/R2 are being evaluated against overall tumour volume response. Different techniques to achieve adequate fat suppression for breast spectroscopy have included STIR, PROSE, TE averaging with STIR and results compared with standard PROBE sequence. As imaging phenotype may be predictive of response, quantitative textural analysis has been implemented using spatial grey level dependence. Results indicate that patients with reduced Ve and Ktrans; are more likely to respond; and that many textural parameters are predictive of early response. Choline has been detected for the first time in normal breast tissue requiring estimation of choline concentration in patients. Use of multi-layer perceptron and radial basis functions neural networks for feature extraction is ongoing to automate multi-source data interrogation. Determination of the comparative effectiveness of breast MR, relative to conventional imaging, in women scheduled for wide local excision is in progress and forms the basis of a Hull based multi-centre study. International collaboration to improve breast receiver coil design for improved 1H as well as 32P imaging is underway.

Impact of MRI on the Delivery and Verification of Intensity Modulated Radiotherapy (IMRT) for Cancer Treatment
Dr G. Liney, Mr R. Garcia Alvarez, Dr A Beavis

IMRT is a state-of-the-art technique that allows accurate sculpting of the radiotherapy dose distribution and hence permits the delivery of the most highly conformal treatment currently achievable,to a variety of tumour sites. It is reliant on inverse planning, which requires accurate tumour volume delineation. This project examines the efficacy of advanced MR imaging techniques for improving the discrimination of both the tumour target and surrounding anatomy using functional and anatomical information. This potentially improves treatment outcome by enabling boost doses to be delivered to active sub-regions within the tumour, whilst conformally avoiding normal tissue. The project has initially focused on the use of dynamic contrast enhanced imaging in head and neck cancers but has recently expanded into the study of intracranial tumours using 1H MR spectroscopy and functional MRI. We have developed software, which incorporates each of the advanced MR techniques into the radiotherapy planning system. This has recently included high-resolution mapping of potentially important biochemical markers. As part of the study we are working with the Chemistry Department at the University of Hull to develop novel gel dosimetry techniques to provide three-dimensional dose verification and quality assurance of IMRT plans. The project additionally involves colleagues in Sheffield who are examining separate planning algorithms for treatment delivery.

Prostate Research Program
Prof. L. Turnbull, Dr P. Gibbs, Dr M. Lowry

Studies continue on: the differentiation of benign from malignant disease, using dynamic contrast-enhanced MRI which incorporates arterial input function allowing estimation of blood volume and tissue perfusion; the use of tetrahedral, trace and anisotropic diffusion imaging to examine the apparent diffusion coefficient of contained water; and incorporation of 3D chemical shift spectroscopic imaging information. These studies are on going in newly diagnosed prostatic malignancies. LREC and Trust approval is currently being sought following collaboration with the Laser Centre in Goole (Prof K Moghissi and colleagues) to examine the role of photodynamic therapy in the treatment of prostatic tumours.

Gynaecological Research Program
Prof L. Turnbull, Dr P. Balan, Dr M. Lowry

Audit of MR findings for gynaecological referrals over a three year period is complete and reveals highly significant differences between MRI, computed tomographic and ultrasound scanning, with MRI achieving the best results (87% overall accuracy and 100% negative predictive value). Evaluation of the uptake characteristics obtained from dynamic contrast-enhanced imaging has shown highly significance differences between benign and malignant lesions. False negative results have been recorded almost exclusively in borderline ovarian malignancies and in ovarian cystadenofibromas. Research is now concentrated on developing single voxel and 3D CSI proton MR spectroscopic techniques for the pelvic organs, to determine the concentration of choline and other metabolites in cyst fluid and solid tissue elements to enhance lesion discrimination. Initial results have failed to identify choline in benign lesions although it is variably present in malignant lesions. Interestingly other novel resonances have been identified exclusively in mucinous ovarian tumours. Comparison of MR staging accuracy with respect to surgical and histopathological findings and potential alteration in patient management is also underway in relation to ovarian, cervical and uterine malignancies. Pharmacokinetic parameters derived from DCE-MRI combined with 1H MR spectroscopy are being used to assess early and late response to first line cytotoxic chemotherapy, in patients with inoperable ovarian malignancies, in comparison with volumetric changes and biochemical markers.