Optimark

Prostate mpMRI was performed using a 3.0-T GE Signa HDxt MR Scanner (GE Healthcare, Milwaukee, USA) with receive only pelvic phased-array coil with 18 channels without endorectal coil. All patients fasted for at least 4 hours before the examination. The prostate images were acquired before and after intravenous injection of 0.2mL/kg of gadoversetamide (Optimark; Mallinckrodt Inc., St. Louis, MO) at a rate of 3mL/second by power injector, followed by 20mL of saline flush.
The MRI examinations were performed using a standardized clinical protocol as recommended in PI-RADS v2 (7 ), including T2-weighted imaging (T2WI), dynamic contrast-enhanced (DCE) imaging, and diffusion-weighted imaging (DWI) (Table-1).
Table 1

Parameter	Axial T2WI	Axial DWI (B50 / 1500 /2000)	Multi plane T2 3D	Axial Dixon Pelvis	Axial DCE
Repetition time (msec)	7500	5500	1200	5.73	3.80
Echo time (msec)	116	84	126	2.46 and 3.69	1.41
Flip angle (degrees)	150	-	120	90	150
Field of view (mm)	150	300	300	280	180
Acquisition matrix	218 x 256	144 x 160	256 x 256	192 x 256	154 x 192
Section thickness (mm), no gaps	3	3.5	1.17	3.0	3.5
Reconstruction voxel imaging resolution (mm/pixel)	0.3 x 0.3	1.5 x 1.5	0.59 x 0.59	1.1 x 1.1	0.9 x 0.9
Acquisition time (min:sec)	04:15	08:43	06:59	00:16	04:58

All the imaging exams were performed in the same technical equipment.
CT scans were performed using a 16-section multidetector row CT scanner (Philips Brilliance Big Bore, Philips Healthcare, Cleveland, OH). Head and neck CT was performed after administration of 80–120 mL of a nonionic contrast (Optiray 320; Mallinckrodt). MRI examinations were performed at 1.5 T MR scan (SignaHDxT system, GE Medical Systems, Milwaukee, WI). MRI protocol included axial T1-and T2-weighted images, coronal T2-weighted fat saturated images and T1-weighted images after intravenous administration of gadolinium-based paramagnetic contrast agent (10 ml of gadoversetamide, Optimark® Mallinckrodt). Two experienced medical radiologists reviewed all CT and MRI images.
Whole body ¹⁸F-FDG PET/CT imaging was performed 60 minutes after intravenous injection of 0.154 mCi/Kg of ¹⁸F-FDG (IPEN-CNEN). Patients with normal blood glucose levels were injected at rest and after at least 4 hours of fasting. Both low dose CT and dedicated PET imaging protocols, starting from the head to the proximal thigh, were acquired in a 64 channel PET/CT (Gemini TOF, Philips Medical Systems). Nuclear medicine specialists with 15 and 25 years of experience reviewed images and SUV data in concordance.

MRI was conducted using three different systems as the study overlapped with the decommissioning of an older MRI unit (Siemens 1.5 Tesla Symphony), installation of an upgraded system (Siemens 3.0 Tesla Skyra), and use of a “bridge” unit (Siemens 1.5 Tesla Symphony equipped with older software). Sequences obtained included T1‐weighted fast spin echo (FSE), T2‐weighted FSE, T1‐ and T2‐weighted fluid attenuated inversion recovery, gradient echo (T2*), and susceptibility‐weighted imaging. T1‐weighted images were also obtained after administration of Gadoversetamide (0.1 mmol/kg, Optimark, Mallinckrodt Inc., St. Louis, MO). For the initial MRI studies, a T1‐weighted, 3D volumetric sequence was also obtained (MP‐RAGE) for use with a veterinary neuronavigation system (BrainSight, Rogue Research, Montreal, Canada). Bite plates affixed with MRI‐compatible fiducial markers were also utilized in this initial MRI study as a prelude to neuronavigation and were created using Hydroplastic impression material (Tak Systems, Wareham, MA).