Dual tuned 13c 1h volume rat coil

Rats with a weight range of 400 to 660 g were scanned in a 3T GE clinical system (GE Healthcare, Milwaukee, WI, USA) equipped with a dual tuned ¹³C/1H volume rat coil (GE healthcare, Brøndby, Denmark). Hyperpolarized [1-¹³C]pyruvate was prepared and polarized in a SpinLab system (GE Healthcare, Milwaukee, WI, USA) in accordance with the standard protocol [19 (link)]. In brief, rats were anesthetized with sevoflurane (3% sevoflurane in 2 L/min air), and a tail vein catheter (0.4 mm) was inserted for injection of [1-¹³C]pyruvate. Upon full polarization (>35%) 1.5 mL (37 °C, pH 7.4) isotonic [1-¹³C]pyruvate solution was injected over 15 s. Anatomical 1H imaging was used for positioning the ¹³C imaging plane. A T2-weighted fast spin echo sequence was used in the axial and coronal orientation covering the liver. Following the anatomical scout, an axial oblique slice-selective (10 mm, 10°) ¹³C-dynamic time series with a repetition time of 1 s (total 120 s, one image/s) was performed. The sequence was initiated before the injection of [1-¹³C]pyruvate. Each individual peak area was fitted using a general linear model fit on the time-domain data, followed by a model-free ratio-metric analysis of the AUC product and substrates.

Rats with a weight range of 400 to 660 g were scanned in a 3T GE clinical system (GE Healthcare, Milwaukee, WI, USA) equipped with a dual tuned ¹³C/¹H volume rat coil (GE healthcare, Brøndby, DK). Hyperpolarized [1-¹³C]-pyruvate was prepared and polarized in a SpinLab system (GE Healthcare) in accordance with the standard protocol [26 (link)]. In brief, rats were anesthetized with sevoflurane (3% sevoflurane in 2 L/min air) and a tail vein catheter (0.4 mm) was inserted for injection of [1-¹³C]-pyruvate, upon full polarization (>35%) 1.5 mL (37 °C, pH 7.4) isotonic [1-¹³C]-pyruvate solution was injected over 15 s. Anatomical ¹H imaging used for positioning the ¹³C imaging plane a T2-weighted fast spin echo sequence was used in the axial and coronal orientation covering the liver. Following the anatomical scout, an axial oblique slice-selective (10 mm, 10°) ¹³C-dynamic time series with a repetition time of 1 s (total 120 s, one image/s). The sequence was initiated before the injection of [1-¹³C]-pyruvate. The individual peak areas were fitted using a general linear model fit on the time domain data, followed by a model-free ratiometric analysis of the area under the curve (AUC) of product and substrates.

Tail vein catheterization was performed for administration of hyperpolarized [1–¹³C]pyruvate. Temperature, peripheral capillary oxygen saturation and respiration rate were monitored throughout the experiment. [1–¹³C]pyruvate was polarized in the Spinlab (GE Healthcare, Brøndby, Denmark). Polarization was performed as previously described^{5 (link)}. Each animal was injected with 1.5 ml (125 mM) hyperpolarized [1–¹³C]pyruvate. MR scans were performed in a 3 T clinical MR system (GE Healthcare, Brøndby, Denmark) equipped with a dual tuned ¹³C/¹H volume rat coil (GE Healthcare, Brøndby, Denmark). A slice-selective ¹³C IDEAL spiral sequence was used for hyperpolarized ¹³C-pyruvate imaging acquiring images every 5 second (sec). The sequence was initiated 20 sec. after the start of injection with the following parameters: flip angle = 10°, 11 IDEAL echoes and one initial spectrum per IDEAL encoding, TR/TE/ΔTE = 100 ms/0.9 ms/0.9 ms, FOV = 80 × 80 mm², 5 × 5 mm real resolution and an axial slice thickness of 15 mm covering both kidneys. Acquired ¹H and ¹³C images were converted to dicom files. Regions of interest (ROI’s) were placed around each kidney in Osirix. Hyperpolarized MR metabolic kinetic analysis was performed by ratiometric analysis according to previous reports^{28 (link)}.