Prostate Biopsy Outcome Using 29 mm Cutting Length

Design Optimization of Nonrotational and Rotational Needle Insertion for Minimal Cutting Forces

The needle insertion is widely used in many medical procedures, particularly in the needle biopsy. The cutting force occurred during the insertion process has a significant effect on the cutting outcome. This paper focuses on minimizing the cutting force for two conventional needle insertion methods, the nonrotational and rotational needle insertion. For the nonrotational needle insertion, the secondary bevel angle and angle of rotation, which are two used for grinding the back-bevel and lancet needles, are considered. For the rotational needles, the effects of the insertion speed and the slice-push ratio on the cutting force are investigated. Levels of these design variables are defined using practical needle design configurations found in the literature. A clear trend of the cutting force decreases as the increase of the inclination angle was observed. The optimal cutting force of nonrotational needles was found as 0.242 N with inclination angle of 69.25 deg for the lancet needle and 0.254 N with inclination angle of 66.24 deg for the back-bevel needle. The optimization of rotational needles yielded a configuration of slice-push ratio as 4.66 and insertion speed as 2.01, which resulted in a minimal cutting force of 0.22 N. Besides, the main effects of and the interaction between the design variables on the cutting force are obtained and discussed. These results provide essential information for selecting geometric and cutting speed parameters for the design of nonrotational and rotational needles.

Can transrectal needle biopsy be optimised to detect nearly all prostate cancer with a volume of ≥0.5 mL? A three-dimensional analysis

OBJECTIVE

To investigate whether transrectal needle biopsy can be optimised to detect nearly all prostate cancer with a tumour volume (TV) of ≥0.5 mL.

MATERIALS AND METHODS

Retrospectively analysed 109 whole-mounted and entirely submitted radical prostatectomy specimens with prostate cancer. All tumours in each prostate were outlined on whole-mount slides and digitally scanned to produce tumour maps. Tumour map images were exported to three-dimensional (3D) slicer software (http://www.slicer.org) to develop a 3D-prostate cancer model. In all, 20 transrectal biopsy schemes involving two to 40 cores and two to six anteriorly directed biopsy (ADBx) cores (including transition zone, TZ) were simulated, as well as models with various biopsy cutting lengths. Detection rates for tumours of different volumes were determined for the various biopsy simulation schemes.

RESULTS

In 109 prostates, 800 tumours were detected, 90 with a TV of ≥0.5 mL (mean TV 0.24 mL). Detection rate for tumours with a TV of ≥0.5 mL plateaued at 77% (69/90) using a 12-core (3 × 4) scheme, standard 17-mm biopsy cutting length without ADBx cores. In all, 20 of 21 (95%) tumours with a TV of ≥0.5 mL not detected by this scheme originated in the anterior peripheral zone or TZ. Increasing the biopsy cutting length and depth/number of ADBx cores improved the detection rate for tumours with a TVof ≥0.5 mL in the 12-core scheme. Using a 22-mm cutting length and a 12-core scheme with additional volume-adjusted ADBx cores, 100% of ≥0.5 mL tumours in prostates ≤ 50 mL in volume and 94.7% of ≥0.5 mL tumours in prostates > 50 mL in volume were detected.

CONCLUSIONS

Our 3D-prostate cancer model analysis suggests that nearly all prostate cancers with a TV of ≥0.5 mL can be detected by 14-18 transrectal needle-biopsy cores. Using longer biopsy cutting lengths and increasing the depth and number of ADBx cores (including TZ) according to prostate volume are necessary as well.

[Length of needle and size of prostatic biopsies influence identification of capsular and extracapsular elements]

OBJECTIVE

To evaluate the influence of the length of prostate biopsies (PB) on identification of prostatic capsule and periprostatic tissue.

MATERIALS AND METHOD

A prospective study was carried out in one center by two urologists during 22 months on 339 consecutive protocols of standardized ten-needle PB (PSA<10ng/ml regardless of digital rectal examination). Pathologic reports were standardized. The conclusion of the pathologic report included the average length of the ten-needle PB (Lm) and the number of prostatic core biopsies on which pathologist identified prostatic capsule and periprostatic tissue (BCI). Protocols of PB were spread in 16 groups depending on the value of Lm in millimeter: [0-1], [1-2], [2-3]... [15-16]. Relationship between Lm's and BCI's was evaluated using the linear regression and the correlation coefficient (r).

RESULTS

Average Lm=10.7 (2.1-15.7; s=2.3) (n=339). Average BCI=6.6 (0-10; s=2.3) (n=339). The value of IGap increased when the value of Lm increased (r=0.89).

CONCLUSIONS

The pathologists better identify the capsule of the prostate and the periprostatic tissue when the PB's are of large size. PB's of small size are of poor quality either for samplings of the prostatic gland or samplings of the capsule and the periprostatic tissues.