Prostate mechanical imaging: a new method for prostate assessment

Abstract

Objectives: To evaluate the ability of prostate mechanical imaging (PMI) technology to provide an objective and reproducible image and to assess the prostate nodularity.

Methods: We evaluated the PMI device developed by Artann Laboratories in a pilot clinical study. For the 168 patients (ages 44 to 94) who presented to an urologist for prostate evaluation, PMI-produced images and assessment of prostate size, shape, consistency/hardness, mobility, and nodularity were compared with digital rectal examination (DRE) findings. The PMI and DRE results were further tested for correlation against a transrectal ultrasound of the prostate (TRUS) guided biopsy for a subgroup of 21 patients with an elevated prostate-specific antigen level.

Results: In 84% of the cases, the PMI device was able to reconstruct three-dimensional (3D) and 2D cross-sectional images of the prostate. The PMI System and DRE pretests were able to determine malignant nodules in 10 and 6 patients, respectively, of the 13 patients with biopsy-confirmed malignant inclusions. The PMI System findings were consistent with all 8 biopsy negative cases, whereas the DRE had 1 abnormal reading for this group. The correlation between PMI and DRE detection of palpable nodularity was 81%, as indicated by the area under the receiver operating characteristic curve. Estimates of the prostate size provided by PMI and DRE were statistically significantly correlated.

Conclusions: The PMI has the potential to enable a physician to obtain, examine, and store a 3D image of the prostate based on mechanical and geometrical characteristics of the gland and its internal structures.

Figure 1

The PMI probe is equipped with two pressure sensor arrays installed on the probe head for prostate imaging (1), and on the probe shaft for sphincter imaging and positioning of the probe(2), and (3) an orientation system integrated in the probe handle.

Figure 2

ROC curve for the PMI detected prostate nodularity vs. abnormal DRE.

Figure 3

PMI examination results for normal and pathology cases. Each examination window is composed of three panels: 2D orthogonal cross-sections of prostate in frontal (upper left) and transversal images (lower left), and a 3-D reconstruction of the prostate (right panel). Case 1: 63 years old patient, PSA 4.2, DRE normal, PMI image presents a prostate with characteristic symmetrical distribution of hardness in right and left lobes of the gland and with pronounced medium groove. Case 2: 61 years old patient, PSA 6.4, both DRE and PMI detected single nodule in the left lobe. TRUS-guided biopsy identified in left base prostatic adenocarcinoma with Gleason score 6.