Patient population: we retrospectively evaluated 50 PCa patients presenting with biochemical relapse [11] after first-line surgery or EBRT.
We also included patients with rising PSA levels after salvage EBRT or androgen deprivation therapy.
All patients underwent 64CuCl2-PET/CT,
18F-Choline-PET/CT and mMRI within 15 days of one another.
Then retrospective co-registration was performed to obtain Fused 64CuCl2 PET/MRI series and Fused 18F-Choline PET/MRI series.
Multiparametric MRI:
All patients underwent mMRI examinations performed with a 1.5 T MRI scanner (Signa HDxt,
GE Healthcare,
Milwaukee,
WI) equipped with an 8-channel pelvic phased-array surface coil.
The procedure was performed according to a standardized protocol [12].
A larger field-of-view FSE T2-weighted (T2w) sequence (slice thickness 4 mm,
interslice gap 0.4 mm,
in-plane resolution 0.6 × 0.6 mm) was set in order to visualize infrarenal para-caval and para-aortic lymph-node stations,
which were also assessed by means of a large field-of-view 3-dimensional spoiled-gradient echo fat-saturated T1-weighted (LAVA) sequence performed after the dynamic contrast-enhanced MRI.
64CuCl2-PET/CT protocol: the production of experimental Copper-64 Chloride (64CuCl2) (Sparkle s.r.l.
Macerata,
Italy) was approved by AIFA.
The radiopharmaceutical was prepared in accordance with Good Manufacturing Practice (GMP) and administered intravenously to fasting patients (at least 6 h).
Whole-body 64CuCl2-PET/CT was carried out 60 min after the injection of 200-250 MBq of 64CuCl2.
All PET scans were acquired in 3D mode by a dedicated PET/CT system (Discovery ST; General Electric Healthcare Technologies,
Milwaukee,
WI).
To evaluate the biodistribution and dosimetry of this radiopharmaceutical,
all 50 patients underwent another two PET/CT acquisitions 4h and 24h after tracer injection.
18F -Choline-PET/CT protocol: 18F-Choline-PET/CT was performed in the fasting state (at least 6 h).
An 18F-Choline activity of 200 MBq (IASOCholine IASON LabormedizinGesmbh&Co.
Kg,
Linz,
Austria) was administered intravenously; data were acquired 20’ after the injection by means of the above-mentioned PET/CT system.
PET was acquired over an acquisition time of 3 min in the same manner as for 64CuCl2-PET/CT and visualized on the same Workstation.
The same CT parameters were also used.
PET/MRI fusion imaging (Fused- 18F -Choline-PET/MRI and Fused- 64CuCl2-PET/MRI): co-registration between MRI and PET images was performed by means of a dedicated software developed for research purposes (Quanta Oncology,
Camelot Biomedical Systems,
Genoa,
Italy) [12,
13,
14].
“Quanta Prostate” is a software able to simultaneously display different MRI datasets,
allowing calculation of color-coded ADC maps from DWI sequences and wash-in/wash-out rate maps from time-intensity curves of DCE-MRI.
Color-coded ADC and perfusion maps can be overlapped on T2w images and examined with different levels of transparency.
Using “Quanta Prostate”,
a deformable registration technique (employing non-linear transformation and spatially varying deformable models) is applied for MRI/PET co-registration,
in order to compensate for changes in patient position and local deformations between different imaging data sets (e.g.,
due to varying degrees of filling of the urinary bladder).
Once MRI/PET co-registration is performed,
the operator can perform quantitative measurements (ADC and SUV-max values) by drawing a ROI on the currently selected ADC or SUV map.
Experienced readers interpreted the images,
and the detection rate (DR) of each imaging modality was calculated.
The detection rate (DR) of each imaging modality was calculated by using histopathology,
clinical or laboratory response and multidisciplinary follow-up as a reference standard.
We performed a patient-based analysis and a lesion-based analysis (Table 1 and 2).