Three-dimensional sampling perfection with application-optimised contrasts using a different flip angle evolutions sequence for routine imaging of the spine: preliminary experience.

OBJECTIVES: The bulk of spinal imaging is still performed with conventional two-dimensional sequences. This study assesses the suitability of three-dimensional sampling perfection with application-optimised contrasts using a different flip angle evolutions (SPACE) sequence for routine spinal imaging. METHODS: 62 MRI examinations of the spine were evaluated by 2 examiners in consensus for the depiction of anatomy and presence of artefact. We noted pathologies that might be missed using the SPACE sequence only or the SPACE and a sagittal T(1) weighted sequence. The reference standards were sagittal and axial T(1) weighted and T(2) weighted sequences. At a later date the evaluation was repeated by one of the original examiners and an additional examiner. RESULTS: There was good agreement of the single evaluations and consensus evaluation for the conventional sequences: κ>0.8, confidence interval (CI)>0.6-1.0. For the SPACE sequence, depiction of anatomy was very good for 84% of cases, with high interobserver agreement, but there was poor interobserver agreement for other cases. For artefact assessment of SPACE, κ=0.92, CI=0.92-1.0. The SPACE sequence was superior to conventional sequences for depiction of anatomy and artefact resistance. The SPACE sequence occasionally missed bone marrow oedema. In conjunction with sagittal T(1) weighted sequences, no abnormality was missed. The isotropic SPACE sequence was superior to conventional sequences in imaging difficult anatomy such as in scoliosis and spondylolysis. CONCLUSION: The SPACE sequence allows excellent assessment of anatomy owing to high spatial resolution and resistance to artefact. The sensitivity for bone marrow abnormalities is limited.

Radiation-induced comet-formation in human skin fibroblasts from radiotherapy patients with different normal tissue reactions.

BACKGROUND: In clinical radiotherapy most patients tolerate the applied dosage with no or moderate side effects. However, 5 to 10% of all individuals show increased acute and/or late reactions. In-vitro test systems are investigated for their suitability for predictive purposes. This paper attempts a correlation between the induction and repair of DNA damage measured in the comet assay and the clinical observed reaction in order to evaluate the suitability of the comet assay for prediction of radiation sensitivity. PATIENTS AND METHODS: Skin fibroblasts of 30 patients with average tissue reactions or acute and/or late increased side effects and cell lines of 4 individuals carrying the heritable disease ataxia telangiectasia (AT) were irradiated in vitro. The induction and repair of DNA damage was measured at different time points after irradiation in the comet assay (single cell gel electrophoresis). These results were compared to the acute and late clinical reactions classified according to the RTOG grading system. RESULTS: The radiation induced DNA damage decreased over time reflecting DNA repair. Cells of the AT individuals showed an elevated damage induction and a reduced repair capacity compared to patients with average tissue reactions. Fibroblasts of patients with increased acute and late side effects exhibited slower DNA repair. In addition to the known lack of cell cycle control, our results indicate that AT cells show reduced DNA repair capacity. CONCLUSIONS: The comet assay seems to be able to detect some types of increased individual radiation sensitivity. In contrast to other predictive in-vitro tests, the comet assay needs less time and fewer cells, which would be useful in a clinical setting.

Radiation-induced micronucleus formation in human skin fibroblasts of patients showing severe and normal tissue damage after radiotherapy.

PURPOSE: Treatment schedule and total dosage in radiation therapy is based on the tumoricidal doses and the tolerance dose of the perifocal normal tissue. Since large-scale variations occur between the patients concerning the side effects, one of the major goals of radiation research recently has been the development of a predictive in vitro assay. This paper is a contribution to that effort. MATERIALS AND METHODS: Skin fibroblasts of patients with normal-tissue reactions or acute and/or late increased side effects and cell lines of four individuals carrying the heritable disease ataxia telangiectasia were irradiated in vitro. The formation of micronuclei was chosen as biological endpoint and the results were compared with the clinically observed side effects. RESULTS: In general, a radiation dose-dependent increase in micronucleus frequency was found. The cells of the majority of the sensitive patients, as well as those of homozygous and heterozygous ataxia telangiectasia individuals, showed a higher micronucleus induction than the average of the donors with normal sensitivity. CONCLUSIONS: The micronucleus test seems to be a very promising tool in the evaluation of radiation sensitivity prior to therapy. However, larger studies are needed to confirm these findings and to optimize the methodology, and it is presumed that a final predictive assay will consist of a combination with other test systems.