Prostatic calcifications: Quantifying occurrence, radiodensity, and spatial distribution in prostate cancer patients

Abstract

Background: To evaluate the prevalence, density, and distribution of prostate calcification in patients with prostate cancer.

Methods: Patients who underwent both Gallium-68 PSMA PET/CT and MRI of the prostate over the course of a year were selected for analysis. The CT images with visible calcifications within the prostate were included and calcifications automatically isolated using a threshold of 130 HU. The corresponding multiparametric MRI was assessed and the peripheral zone, transition zone, MRI-visible tumor, and urethra manually contoured. The contoured MRI and CT images were registered using rigid registration, and calcifications mapped automatically to the MRI contours.

Results: A total of 85 men (age range 50-88, mean 69 years, standard deviation 7.2 years) were assessed. The mean serum Prostate Specific Antigen PSA was 16.7, range 0.12 to 94.4. Most patients had intermediate-risk disease (68%; Gleason grade group 2 and 3), 26% had high-risk disease (Gleason grade group 4 and 5), and 6% had low-risk disease (Gleason grade group 1). Forty-six patients out of 85 (54%) had intraprostatic calcification. Calcification occurred more in transition zone than the peripheral zone (65% vs. 35%). The mean density of the calcification was 227 HU (min 133, max 1,966 HU). In 12 patients, the calcification was within an MRI-visible tumor, in 24 patients, there were calcifications within a 9 mm distance of the tumor border, and in 9 patients, there were calcifications located between the urethra and tumor.

Conclusions: Calcifications are common in patients with prostate cancer. Their density and location may make them a significant consideration when planning treatment or retreatment with some types of minimally invasive therapy.

Keywords: Calcification; HIFU; PSMA PET; Prostate MRI; Prostate cancer; Radiotherapy.

Graphical abstract

Fig. 1

T2-weighted MR image slice (left), the corresponding CT image slice (middle), and thresholded image (right) for 3 example cases: (A) previous left-sided HIFU on which calcifications (highlighted by white arrows) are visible within the transition zone midgland contour (blue). (B) Calcification is visible between the urethra and tumor. (C) Calcification is present within the tumor. The peripheral zone midgland (blue), urethra (purple), tumor (red), and area between urethra and tumor (purple dotted) are also shown. (Color version of figure is available online.)