In vitro and in vivo comparison of two-, three- and four-point Dixon techniques for clinical intramuscular fat quantification at 3 T.

OBJECTIVE: To compare Dixon-based MRI techniques for intramuscular fat quantification at 3 T with MR spectroscopy (MRS) in vitro and in vivo. METHODS: In vitro, two- three- and four-point mDixon (Philips Medical Systems, Best, Netherlands) sequences with 10°, 20° and 30° flip angles were acquired from seven test phantoms with sunflower oil-water percentages of 0-60% sunflower oil and calculated fat-water ratios compared with MRS. In vivo, two- three- and four-point mDixon sequences with 10° flip angle were acquired and compared with MRS in the vastus medialis of nine healthy volunteers (aged 30.6 ± 5.3 years; body mass index 22.2 ± 2.6). RESULTS: In vitro, all mDixon sequences correlated significantly with MRS (r > 0.97, p < 0.002). The measured phantom percentage fat depended significantly on the flip angle (p ≤ 0.001) and mDixon sequence (p = 0.005). Flip angle was the dominant factor influencing agreement with MRS. Increasing the flip angle significantly increased the overestimation of the mDixon sequences compared with MRS. In vivo, a significant difference was observed between sequences (p < 0.001), with all mDixon sequences overestimating the intramuscular fat content of the vastus medialis muscle compared with MRS. Two-point mDixon agreed best with MRS and had comparable variability with the other mDixon sequences. CONCLUSION: This study demonstrates that mDixon techniques have good linearity and low variability for use in intramuscular fat quantification. To avoid significant fat overestimation with short repetition time, a low flip angle should be used to reduce T1 effects. ADVANCES IN KNOWLEDGE: This is the first study investigating the optimal mDixon parameters for intramuscular fat quantification compared with MRS in vivo and in vitro.

Rectal tumour volume (GTV) delineation using T2-weighted and diffusion-weighted MRI: Implications for radiotherapy planning.

PURPOSE: To compare the rectal tumour gross target volume (GTV) delineated on T2 weighted (T2W MRI) and diffusion weighted MRI (DWI) images by two different observers and to assess if agreement is improved by DWI. MATERIAL AND METHODS: 27 consecutive patients (15 male, range 27.1-88.8 years, mean 66.9 years) underwent 1.5T MRI prior to chemoradiation (45Gy in 25 fractions; oral capecitabine 850mg/m(2)), including axial T2W MRI (TR=6600ms, TE=90ms) and DWI (TR=3000ms, TE=77ms, b=0, 100, 800s/mm(2)). 3D tumour volume (cm(3)) was measured by volume of interest (VOI) analysis by two independent readers for the T2W MRI and b800 DWI axial images, and the T2W MRI and DWI volumes compared using Mann-Whitney test. Observer agreement was assessed using Bland-Altman statistics. Significance was at 5%. RESULTS: Artefacts precluded DWI analysis in 1 patient. In the remaining 26 patients evaluated, median (range) T2W MRI MRI and DWI (b=800s/mm(2)) 3D GTVin cm(3) were 33.97 (4.44-199.8) and 31.38 (2.43-228), respectively, for Reader One and 43.78 (7.57-267.7) and 42.45 (3.68-251) for Reader Two. T2W MRI GTVs were slightly larger but not statistically different from DWI volumes: p=0.52 Reader One; p=0.92 Reader Two. Interobserver mean difference (95% limits of agreement) for T2W MRI and DWI GTVs were -9.84 (-54.96 to +35.28) cm(3) and -14.79 (-54.01 to +24.43) cm(3) respectively. CONCLUSION: Smaller DWI volumes may result from better tumour conspicuity but overall observer agreement is not improved by DWI.

Morbidity and mortality analysis of 200 treatments with cytoreductive surgery and hyperthermic intraoperative intraperitoneal chemotherapy using the coliseum technique.

BACKGROUND: Peritoneal carcinomatosis from gastrointestinal cancers is a fatal diagnosis without special combined surgical and chemotherapy interventions. Guidelines for cytoreductive surgery and hyperthermic intraoperative intraperitoneal chemotherapy (HIIC) by using the Coliseum technique have been developed to treat patients with peritoneal carcinomatosis and other peritoneal surface malignancies. The purpose of this study was to analyze the morbidity and mortality of patients undergoing cytoreductive surgery and HIIC by using mitomycin C. METHODS: Data were prospectively recorded on 183 patients who underwent 200 cytoreductive surgeries with HIIC between November 1994 and June 1998. Seventeen of the 183 patients returned for a second-look surgery plus HIIC. All HIIC administrations occurred after cytoreduction and used continuous manual separation of intra-abdominal structures to optimize drug and heat distribution. Origins of the tumors were as follows: appendix (150 patients), colon (20 patients), stomach (7 patients), pancreas (2 patients), small bowel (1 patient), rectum (1 patient), gallbladder (1 patient), and peritoneal papillary serous carcinoma (1 patient). Morbidity was organized into 20 categories that were graded 0 to IV by the National Cancer Institute's Common Toxicity Criteria. In an attempt to identify patient characteristics that may predispose to complications, each morbidity variable was analyzed for an association with the 25 clinical variables recorded. RESULTS: Combined grade III/IV morbidity was 27.0%. Complications observed included the following: peripancreatitis (6.0%), fistula (4.5%), postoperative bleeding (4.5%), and hematological toxicity (4.0%). Morbidity was statistically linked with the following clinical variables: duration of surgery (P < .0001), the number of peritonectomy procedures and resections (P < .0001), and the number of suture lines (P = .0078). No HIIC variables were statistically associated with the presence of grade III or grade IV morbidity. Treatment-related mortality was 1.5%. CONCLUSIONS: HIIC may be applied to select patients with peritoneal carcinomatosis from gastrointestinal malignancies with 27.0% major morbidity and 1.5% treatment-related mortality. The frequency of complications was associated with the extent of the surgical procedure and not with variables associated with the delivery of heated intraoperative intraperitoneal chemotherapy. The technique has shown an acceptable frequency of adverse events to be tested in phase III adjuvant trials.

The ex vivo effect of ligation technique on the static frictional resistance of stainless steel brackets and archwires.

This ex vivo investigation compared the effect of various orthodontic ligation techniques on the static frictional resistance of stainless steel brackets and archwires under both dry and wet conditions. The techniques studied were: elastomeric modules tied conventionally and in a 'figure of 8' pattern, stainless steel ligatures, and Teflon-coated ligatures. The first part of the investigation involved the construction of calibration curves for each of the materials, so an estimate of the normal force exerted by the ligatures could be ascertained. Secondly, a pair of ligature locking pliers were modified so that ligatures could be placed with a standardized force. Finally, the four methods of ligation were directly compared on a specially constructed testing apparatus. Results revealed that elastomeric modules tied in a 'figure of 8' pattern produced significantly more friction than any other method tested, under both dry and wet conditions. No significant differences in frictional resistance were found between conventionally tied elastomeric modules and stainless steel ligatures. Teflon-coated ligatures, however, were associated with the lowest frictional forces. The results of the calibration tests indicated that the normal forces exerted by all four methods of ligation may be higher than previously estimated.

Effect of mycoprotein on blood lipids.

This metabolic study was designed to investigate the effects of mycoprotein on blood lipids. Mycoprotein is a food produced by continuous fermentation of Fusarium graminearum (Schwabe) on a carbohydrate substrate. Two groups of subjects with slightly raised cholesterol concentrations took part in the 3-wk study. The experimental group was fed mycoprotein in place of meat and the control diet contained meat. There was no change in plasma cholesterol in the control group but there was a 13% reduction in the mycoprotein group. Low-density lipoprotein (LDL) increased in the control group by 12% and decreased by 9% in the mycoprotein group. High-density lipoprotein (HDL) decreased by 11% in the control group but increased by 12% in the mycoprotein group. In each case the group ANOVA differences between variables were statistically significant. It is clear from these results that lipid variables are advantageously altered by mycoprotein consumption.