ABSTRACT
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.
Subject(s)
Diffusion Magnetic Resonance Imaging/methods , Image Interpretation, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Radiotherapy Planning, Computer-Assisted/methods , Radiotherapy, Image-Guided/methods , Rectal Neoplasms/pathology , Rectal Neoplasms/radiotherapy , Adult , Aged , Aged, 80 and over , Algorithms , Humans , Image Enhancement/methods , Middle Aged , Observer Variation , Reproducibility of Results , Sensitivity and Specificity , Tumor BurdenABSTRACT
PURPOSE: This study was done to evaluate whether and which of the magnetic resonance diffusion-weighted imaging (MR-DWI) parameters - apparent diffusion coefficient (ADC), diffusion (D) or perfusion fraction (f) - correlates with the degree of chronic liver disease progression. MATERIALS AND METHODS: Twenty-eight patients were evaluated with abdominal MR-DWI from March to November 2010: seven healthy volunteers, seven patients with chronic liver disease F0-F2 (METAVIR score), seven F3-F4 Child-Pugh A, and seven F4 Child-Pugh BC, classified as groups 1-4, respectively. DWI acquisitions were performed during breath-holding (b = 0-150 s/mm(2) and 1,000) and free breathing (multi-b = 0-200-400-600-800-1,000 s/mm(2)). Using a double-blind control procedure, two observers estimated ADC, D, and f by applying a region of interest (ROI) in 4/12 sections in the middle-lower portion of the right hepatic lobe. Statistical analysis was done with analysis of variance (ANOVA). RESULTS: A reduction in the mean value of f, ADC(150) and, to a lesser extent, ADC(1,000) is shown to progress from healthy volunteers (group 1) to cirrhosis patients (group 4), with wide overlap among groups. There were no statistically significant changes of D. CONCLUSIONS: Our results indicate that stratifying patients with chronic liver disease for clinical purposes cannot be done with DWI. However, there is a tendency among groups for reduced perfusion-related parameters as chronic liver disease progresses.
