Table 2. Technical details of the CE-FDG-PET-MR.
| MR sequence | Plane | Area scanned | iPat | TR (ms) | TE (ms) | Matrix | NEX | FOV (mm) | Thickness (mm) | Gap (mm) | FA (degrees) | Voxel size (mm) | TI (ms) | Fat saturation |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Co-aquired with PET | ||||||||||||||
| T1w 2-Point Dixon VIBE | Coronal | Whole body | 2 | 3.6 | 1st TE 1.225 2nd TE 2.45 | 79 × 192 | 1 | 500 | 3.1 | 0 | 100 | 4.1 × 2.6 × 3.1 | ||
| STIR | Coronal | Whole body | 3 | 4482–5631 | 81–87 | 186 × 384 | 1 | 450 | 5.0 | 1.5 | 1.6 × 1.2 × 5.0 | 220–230 | ||
| DWI (b-values 50–400–800) | Axial | Whole body | 2 | 9100–18 800 | 66–83 | 112 × 156 | 2 | 420 | 6.0 | 0.6 | 2.7 × 2.7 × 6.0 | 220 | ||
| T2w HASTE | Axial | Whole body | 2 | 1400 | 86–97 | 288 × 384 | 1 | 380 | 6.0 | 0.6 | 1.3 × 1.0 × 6.0 | |||
|
Whole-body contrast-enhanced sequences acquired after PET | ||||||||||||||
| T1w VIBE | Coronal | Whole body | 3 | 2.54–4.06 | 1.14–1.91 | 248 × 288 | 1 | 400 | 3.0 | 0 | 9o | 1.4 × 1.4 × 1.5 | Quick spectral fat saturation | |
| T1w VIBE | Axial | Whole body | 2 | 4.06–4.1 | 1.81–1.91 | 180 × 230 | 1 | 380 | 3.0 | 0 | 9o | 1.6 × 1.2 × 3.0 | Quick spectral fat saturation | |
| PET | BP | Acquisition time/BP (min) | Iterative reconstruction algorithm | Iterations | Subsets | FOV axial (mm) | Voxel size (mm3) | Image grid |
|---|---|---|---|---|---|---|---|---|
| 5–6 | 4 | AW OSEM 3D | 3 | 21 | 258 | 2.0 × 2.0 × 2.0 | 172x172 |
Abbreviations: AW OSEM 3D=three-dimensional attenuation weighted ordered subsets expectation maximisation iterative reconstruction algorithm; BP=bed position; CE-FDG-PET-CT=contrast enhanced-fluorodexossyglucose-positron emission tomography-computed tomography; DWI=diffusion weighted imaging; FA=flip angle; FOV=field of view; FS=fat saturated; FSE=fast spin echo; GE=gradient echo; HASTE=half Fourier single shot fast spin echo T2-weighted; iPat=integrated parallel acquisition technique; MR, magnetic resonance; SPAIR=spectral adiabatic inversion recovery; STIR=short tau inversion recovery; TE=time of echo; TI=time of inversion; TR=time of repetition; VIBE=volume interpolated breath hold T1 weighted.
PET images were co-acquired with MR sequences, starting from the mid thighs and moving towards the head. BP in the thighs, pelvis and neck were acquired during shallow free breathing, while, in the upper abdomen and thorax, they were acquired during expiratory breath-hold. PET data underwent automatic attenuation correction using attenuation maps generated from the 2-point Dixon sequence. The reconstruction software automatically corrects for the delay between the time of FDG injection and the time of PET data acquisition for each bed position.
0.1 mmol kg−1 (0.5 mmol ml−1) of Gadopentate dimeglumine (Gd-DTPA; Magnevist, Bayer Pharma AG, Berlin, Germany) were injected in an antecubital vein at 3 ml s−1 followed by the same volume of saline at 3 ml s−1 using a power injector (Spectris Solaris EP, Medrad, Warrendale, PA, USA) and dedicated breast or upper abdominal dynamic protocols were run. The technical details of the breast and of the dynamic upper abdominal sequences are not described in the current table because the corresponding images were not evaluated in the present study. We describe the VIBE axial and coronal sequences used to cover the whole body at the end of the breast or upper abdominal dynamic protocols.