Page 136 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt
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Parametric Mapping
To assess the spatial distribution of 18FLT uptake within the lungs, volume of distribution was estimated from the slope of the linear regression on the Logan plot [31]. A parametric 3‐dimentional map was generated by using volume of distribution values measured per voxel basis, typically 200000 voxels (2mm2 per voxel) for a human subject.
Animals and Experimental Design
Adult male Sprague‐Dawley (SD) rats (body weight 200‐250g) (Charles River, UK) were used. All experiments were conducted in accordance with the UK Home Office Animals (Scientific Procedures) Act 1986 (London, UK). Pulmonary hypertension was induced by subcutaneous injection of monocrotaline (MCT, 60 mg/kg; Sigma‐Aldrich).
In vivo experiments were designed as follows: a) 18FLT PET – following MCT induced PH progression; 18FLT PET scans were performed in control and MCT PAH rats one week and four weeks after injection. b) 18FLT PET – to assess the effects of treatments in MCT PH model; rats were divided into 4 groups (n=6 per group) (i) control (C), (ii) MCT 4 weeks (4W) and MCT rats treated with (iii) Dichloroacetate acid 70mg/kg/day in drinking water (DCA, Sigma‐Aldrich, UK), (iv) imatinib 100mg/kg/day (IMA, LC Laboratories, USA) by oral gavage. Each treatment was started 2 weeks post MCT injection and continued for the following 2 weeks. At the end of the treatment, 18FLT PET scans were performed and tissues were collected for biochemical and histological examination.
In vivo 18FLT PET
In vivo imaging was performed using a Siemens Inveon small‐animal multimodality PET/CT system (Siemens Healthcare Molecular Imaging). Briefly, rats were anaesthetized with isoflurane (2‐4%), ventilation was adjusted to maintain pO2, pCO2 and pH within normal range. After the completion of the CT scan, 18FLT (approximately 35 MBq, <0.5ml) was injected through tail vein catheter. Dynamic emission scans were acquired in list‐mode format for 60 minutes using conventional full‐ ring, whole‐body PET. During PET scanning, serial blood samples were taken via a femoral artery line (20 μl each) 8 samples at 1st minute, and then at 2, 3, 5, 10, 15, 30, 45 and 60 minutes. At the end, animals were sacrificed and tissue samples (lung, RV, kidney, liver) were collected for gamma‐ counting, as well as snap frozen for biochemical measurement. The ratio of RV to left ventricle plus the septum mass (RV/ LV + septum) was used as an index of RV hypertrophy. Left lungs were inflated and fixed with 4% formalin for histology examination.



























































































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