Novel Imaging in Staging of Primary Prostate Cancer

Computed tomography of the thorax, abdomen and pelvis will be performed as a part of routine clinical evaluation protocol. The imaging will be done with contrast agent if there are no clinical contraindications for the use of contrast agent.

Planar bone scintigraphy will be performed as a part of routine clinical evaluation protocol. The subjects will be positioned supine on a Discovery NM/CT 670 CZT, a digital SPECT/CT scanner (General Electric Healthcare). The scanner includes a dual-detector, free-geometry integrated nuclear imaging camera with the advanced digital CZT detector technology combined with the high-performance Optima CT540 subsystem. Whole-body planar images will be scanned from the anterior and posterior views three hours after the intravenous injection of 670 MBq of 99mTc-HMDP. A wide-energy high-resolution (WEHR) collimator, a scan speed of 13 cm/min, a zoom of 1.0 and a matrix size of 256 x 1024 are used in the scintigraphy.

SPECT/CT imaging will be carried out after acquisition of the planar images with the same scanner. Three bed positions of SPECT data will be acquired from the top of the head to mid femoral level using WEHR collimators. A non-circular orbit, 60 views with 15-s scanning time per view will be acquired during 180 degrees of rotation. A 128 x 128 matrix size, a zoom of 1.0 and 15% photopeak and lower scatter energy windows are used. After SPECT a CT topogram and a low-dose tomogram with a modulated mAs (noise index \~ 70), 120 kVp, a pitch of 1.35 and a 2.5-mm slice thickness are scanned. The co-registration of SPECT and CT data is verified after which the SPECT images are reconstructed using modern iterative ordered subsets expectation (OSEM) reconstruction algorithm from General Electric or Hermes Medical Solutions, which includes, e.g., 10 iterations and 5 subsets and attenuation, collimator and scatter corrections.

Magnetic resonance imaging examination will be performed using a 1.5T (Philips 1.5T Ingenia, Best, Netherlands and/or Siemens 1.5T Aera/Avant, Erlangen, Germany) or 3T (Philips 3T Ingenia, Best, Netherlands and/or Siemens 3T Skyra fit, Erlangen, German) MR system. The body matrix coil in combination with a spinal coil will be used for image acquisition. T1-weighted anatomic imaging, STIR fat suppressed images and DWI will be performed in axial and coronal directions. DWI will be obtained with single-shot 2D spin-echo echo-planar imaging. The total scan time will be approximately 50 minutes.

18F-PSMA-1007 is produced by radiolabelling with fluorine-18 produced by irradiating oxygen-18. Administration of the formulated solution is done shortly (\<10h) after production. Imaging is carried out with digital PET/CT scanner (Discovery MI;General Electric Medical Systems, Milwaukee, WI, USA). The patients receive intravenous injection of 200-300 MBq (3 MB/kg) of 18F-PSMA-1007 diluted in 3-5 ml of saline as a 60-sec bolus which will be promptly flushed with saline. Before data acquisition patients will be asked to void. A static emission scan will be acquired 60-min from tracer injection over whole body. The sinogram data will be corrected for deadtime, decay and photon attenuation and reconstructed in a 256x256 matrix. Image reconstruction follows a fully 3D maximum likelihood ordered subsets expectation maximization algorithm incorporating random and scatter correction with two iterations and 28 subsets.The final in-plane full-width half-maximum of the systems is \< 6 mm.