Bevel angle study of flexible hollow needle insertion into biological mimetic soft-gel: Simulation and experimental validation

BACKGROUND

A thorough understanding of cutting-edge geometry and cutting forces of hollow biopsy needles are required to optimise needle tip design to improve fine needle aspiration procedures.

OBJECTIVES

To incorporate the dynamics of needle motion in a model for flexible hollow bevel tipped needle insertion into a biological mimetic soft-gel using parameters obtained from experimental work. Additionally, the models will be verified against corresponding needle insertion experiments.

METHODS

To verify simulation results, needle deflection and insertion forces were compared with corresponding experimental results acquired with an in-house developed needle insertion mechanical system. Additionally, contact stress distribution on needles from agar gel for various time scales were also studied.

RESULTS

For the 15°, 30°, 45°, 60° bevel angle needles, and 90° blunt needle, the percentage error in needle deflection of each needle compared to experiments, were 7.3%, 9.9%, 8.6%, 7.8%, and 9.7% respectively. Varying the bevel angle at the needle tip demonstrates that the needle with a lower bevel angle produces the largest deflection, although the insertion force does not vary too much among the tested bevel angles.

CONCLUSION

This experimentally verified computer-based simulation model could be used as an alternative tool for better understanding the needle-tissue interaction to optimise needle tip design towards improved biopsy efficiency.

Multicentre clinical evaluation of the safety and performance of a simple transperineal access system for prostate biopsies for suspected prostate cancer: The CAMbridge PROstate Biopsy DevicE (CamPROBE) study

Objectives:

To report the prospective multicentre clinical evaluation of a first-in-man disposable device, Cambridge Prostate Biopsy Device, to undertake local anaesthetic outpatient transperineal prostate biopsies.

Material and methods:

Disposable single-use Cambridge Prostate Biopsy devices were manufactured based on a previous prototype. The lead site developed a user training course and disseminated the method to other sites. The Cambridge Prostate Biopsy Device (CamPROBE) was offered as an alternative to transrectal ultrasound guided biopsy to men due for a biopsy as part of their clinical management. Data on safety (infections and device performance), clinical utility, patient reported experience, biopsy quality and cancer detection were collected. Procedure time and local anaesthetic use was recorded in the lead site. The study was funded by a United Kingdom National Institute for Health Research (NIHR) i4i product development award.

Results:

A total of 40 patients were recruited (median age 69 y) across six sites; five sites were new to the procedure. Overall, 19/40 were first prostate biopsies and 21/40 repeat procedures. Both image-targeted and systematic biopsy cores taken. There were no infections, device deficiencies or safety issues reported. The procedure was well tolerated with excellent patient-reported perception and low pain scores (median of 3, scale 0–10). Histopathology quality was good and the overall cancer diagnosis rate (first diagnostic procedures) was 68% (13/19) and for significant cancers (⩾ histological Grade Group 2), 47% (9/19). In the lead centre (most experienced), median procedure time was 25 minutes, and median local anaesthetic use 11 ml (n=17).

Conclusions:

Data from this device evaluation study demonstrate that the United Kingdom-developed Cambridge Prostate Biopsy Device/method for transperineal biopsies is safe, transferable and maintains high diagnostic yields. The procedure is well tolerated by patients, suited to the local anaesthetic outpatient setting and could directly replace transrectal ultrasound guided biopsy.

Level of evidence:

Level III

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.

Impact of a novel biopsy instrument with a 25-mm side-notch needle on the detection of prostate cancer in transrectal biopsy

OBJECTIVES

To evaluate the impact of a novel biopsy instrument that extends the length of the side-notch on the detection of prostate cancer in transrectal needle biopsy.

METHODS

We collaborated with a biopsy needle manufacturer and developed a novel biopsy instrument (PRIMECUT II long-notch type) with a 25-mm side-notch length and 28-mm stroke length to take longer tissue cores. The sampled core length, cancer detection rate, pain and complications of 489 patients who underwent transrectal biopsy using the long-notch needle were compared with those of 469 patients who underwent biopsy using a normal instrument with a 19-mm side-notch length and 22-mm stroke length.

RESULTS

The mean length of tissue taken by the long-notch needle was significantly longer than that of tissue taken by the normal-notch needle (16.3 vs 22.4 mm, P < 0.001). The overall cancer detection rate was 42.0% for the normal-notch needle and 51.1% for the long-notch needle (P = 0.005). In patients with a prostate volume of 20-40 mL, the cancer detection rate for the long-notch needle was especially higher than that for the normal-notch needle (74.2% vs 47.5%, P < 0.001). Multivariate analysis showed that the long-notch needle improved cancer detection significantly (odds ratio 1.702, P < 0.001). There were no differences of pain during biopsy and complication between the two groups.

CONCLUSIONS

The novel biopsy instrument with a 25-mm side-notch can take longer tissue samples safely and has a significantly higher rate of prostate cancer detection in transrectal biopsy.

Determining the Optimal Number of Core Needle Biopsy Passes for Molecular Diagnostics

PURPOSE

The number of core biopsy passes required for adequate next-generation sequencing is impacted by needle cut, needle gauge, and the type of tissue involved. This study evaluates diagnostic adequacy of core needle lung biopsies based on number of passes and provides guidelines for other tissues based on simulated biopsies in ex vivo porcine organ tissues.

METHODS

The rate of diagnostic adequacy for pathology and molecular testing from lung biopsy procedures was measured for eight operators pre-implementation (September 2012-October 2013) and post-implementation (December 2013-April 2014) of a standard protocol using 20-gauge side-cut needles for ten core biopsy passes at a single academic hospital. Biopsy pass volume was then estimated in ex vivo porcine muscle, liver, and kidney using side-cut devices at 16, 18, and 20 gauge and end-cut devices at 16 and 18 gauge to estimate minimum number of passes required for adequate molecular testing.

RESULTS

Molecular diagnostic adequacy increased from 69% (pre-implementation period) to 92% (post-implementation period) (p < 0.001) for lung biopsies. In porcine models, both 16-gauge end-cut and side-cut devices require one pass to reach the validated volume threshold to ensure 99% adequacy for molecular characterization, while 18- and 20-gauge devices require 2-5 passes depending on needle cut and tissue type.

CONCLUSION

Use of 20-gauge side-cut core biopsy needles requires a significant number of passes to ensure diagnostic adequacy for molecular testing across all tissue types. To ensure diagnostic adequacy for molecular testing, 16- and 18-gauge needles require markedly fewer passes.

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.

Use of end-cutting needles in ultrasound-guided biopsy of neck lesions

The management of a neck mass is dictated by its nature, location and extent. Pathological diagnosis by fine needle aspiration cytology (FNAC) or core biopsy is often required before proceeding to definitive treatment. It is not uncommon for the cytology result to come back as inadequate for various reasons. The unique design of the end-cutting biopsy needle in our experience makes it a good choice for use in obtaining both transcutaneous and intraoral biopsy under ultrasound guidance of neck lesions and serves as a useful alternative or adjunct to FNAC. Although there is, as yet, only a limited evidence base about end-cutting in comparison to side-cutting needles, they carry several potential advantages.

KEY POINTS

End-cutting needles are safe to use for lesions close to vital structures. End-cutting needles yield sufficient tissue samples in a single pass. End-cutting biopsy needles are a useful adjunct to FNAC.

The impact of core biopsy fragmentation in prostate cancer

OBJECTIVES

Since accurate tumor localization and quantification are essential requisites avoiding prostate cancer overtreatment, we analyzed the impact of core fragmentation and the relation between core biopsy taken and pathological information in regard to cancer extension and aggressiveness (Gleason score).

METHODS

One hundred and ninety-nine men submitted to trans-rectal prostate biopsy by the same urologist between October 2006 and October 2008 were included, and the number of cores obtained by biopsy compared to the number of cores examined by the same pathologist.

RESULTS

Total core number obtained by biopsy was 21.54 (± 3.56) compared to 24.08 (± 4.77) examined by the pathologist, P < 0.01. Dividing prostate gland by areas such as base, mid and apical right and left, all areas showed statistically different core number between biopsy and pathological examination report (P < 0.01). Mean ratio of positive core cancer length was 0.41 (± 0.12) and 0.32 (± 0.8) comparing individual and overall cores analysis, respectively (P < 0.01). The mean Gleason score in the individual and overall cores analysis were 6.6 (6-9) and 6.3 (6-9), respectively, P < 0.01.

CONCLUSIONS

Considering the ongoing trend for earlier diagnosis of increasing numbers of younger men with low-risk prostate cancer, this study is original and demonstrates the possibility of core fragmentation, explaining in part over- and under-staging. One core per container and an overall Gleason score and percentage of adenocarcinoma for each container are encouraged.

Coaxial cutting needle biopsies: how important is it to rotate the cutting needle between passes?

AIM

To use an in-vitro model to measure the effect of turning the notch of the cutting needle between passes on the mass of core biopsy material obtained from a typical coaxial biopsy system when multiple passes are performed.

METHODS

A coaxial guide needle was placed within tissue-equivalent agar cylinders and a cutting biopsy needle was used to take core biopsies. Two, three, or four sequential biopsies were performed on the same cylinder with the notch of the cutting needle either inserted facing in the same direction (no rotation) or placed in a sequence of different directions (rotation). The mass of the tissue core obtained at each biopsy pass was measured. A post hoc telephone questionnaire of radiologists across Australia was also undertaken to analyse current practice in the context of these results.

RESULTS

There were statistically significant increases in the mass of tissue obtained using rotation compared with no rotation. Using rotation, the total mass of tissue obtained from three passes was increased by 32.8% (95% CI 23.9-41.7%) and from four passes was increased by 45% (95% CI 37.2-52.9%). The mass of the second pass cores was statistically significantly greater (p<0.001). Fifty-nine percent of Australian radiologists surveyed do not currently change the rotation of the biopsy needle between passes.

CONCLUSION

This in-vitro model confirms that the notch of the cutting needle should be placed into different directions at each pass whenever a coaxial cutting biopsy system is being used to maximize the mass of tissue obtained.

Prostate Biopsy Outcome Using 29 mm Cutting Length

OBJECTIVES

The aim of the study was to compare the prostate biopsy outcome by using either standard or extended cutting length of the needles.

MATERIAL AND METHODS

A total of 74 consecutive prostates from radical prostatectomy were used. Two sextant biopsies were performed ex vivo. We developed a precise simulation of a transrectal biopsy procedure using ultrasound for guiding the needle. In the first set of biopsies an 18-gauge tru cut needle with 19 mm cutting length, powered by a automatic biopsy gun was used. In the second set a single use gun with an 18-gauge end-cutting needle and 29 mm cutting length was used.

RESULTS

In the set of sextant biopsies using 19 mm cutting length 49 (66%) carcinomas were found. In the set of sextant biopsies using 29 mm cutting length 58 (78%) of the tumors were detected. 24 (32%) prostates showed tumor in the transition zones, but there was no transition-zone-only cancer in this study. Nevertheless taking longer cores led to an improvement in prostate cancer detection of 18%.

CONCLUSIONS

In this ex vivo setting the use of 29 mm cutting length for prostate biopsy led to an significant improvement in cancer detection. As we found the end-cutting needle not suitable for use in the patient, these results support the idea to develop a longer tru cut needle and corresponding gun for further clinical investigations.

Can We Obtain Better Specimens with an End-Cutting Prostatic Biopsy Device?

OBJECTIVE

Our aim was to compare the tissue yield of two different prostate biopsy instruments: the newer end-cut versus standard side-notch technique.

METHODS

A total of 87 patients, who underwent transrectal ultrasound guided prostate biopsy were included in the study between February 2003 and July 2003. Twenty-five patients underwent prostate biopsy with the end-cut technique with a stroke length of 33 mm (EC-33), 25 patients were biopsied with a stroke length of 23 mm of the same instrument (EC-23) whereas the remaining 37 patients underwent biopsy with an instrument working with side-notch technique with a 22 mm stroke length (SN). The length, weight and weight/length ratio (WLR) were measured for each biopsy core. The pathologic specimens were evaluated qualitatively. The length, weight and WLR as well as the complication rates, pain, zero biopsy rates, pathologic quality and cancer detection rates were compared between the groups.

RESULTS

Three groups were similar according to age, PSA values (free, total, free/total), prostate volumes (TZ, total) and PSA densities. The cancer detection rate was not statistically different between groups and was overall 20,9%. As the groups were compared according to mean core lengths, weights and densities the sequence was found to be EC-33>EC-23>SN. The EC group had higher prostatic glandular capture rates and better pathological quality. However, the zero biopsy rates were 12%, 7% and 1% for EC-33, EC-23 and SN groups, respectively and the difference was statistically significant. The complication rates after biopsy were similar for each group. The mean visual analogous scale scores were not significantly different between the groups. Another interesting finding was that cores containing cancer were heavier and denser than the others regardless of the instrument type.

CONCLUSION

The use of the presented new instrument, enables to obtain longer, heavier and denser cores with a higher pathologic quality and glandular coverage without increasing the number of biopsies and morbidity. However, the relatively high zero biopsy rate is a handicap that needs to be improved.

The Long Core Needle with an End-Cut Technique for Prostate Biopsy: Does It Really Have Advantages When Compared with Standard Needles?

OBJECTIVE

To evaluate the failure rate, core length and fragmentation rate for each different stroke length of the end-cut (BioPince) needle in order to show the performance of the needle for different stroke lengths and compare these with the standard side-notch needle.

METHODS

TRUS guided biopsy of the prostate was performed on 86 consecutive men between June 2002 and May 2003. The patients were randomized into two groups with 43 men in each group. Patients in group A underwent 8 core biopsy with the end-cut needle in different stroke lengths; 13, 23 and 33mm respectively. Patients in group B underwent 8 core biopsy with the side-notch needle. The cores have been evaluated and compared for failure rates, core lengths, number of core lengths under 5mm and fragmentation rates.

RESULTS

When the end-cut needle was used, a significant number of failure rates was noted; with an overall failure rate of 16%. The failure rates were 26% for 13mm stroke length, 18% for 23mm stroke length and 10% for 33mm stroke length respectively. These failure rates showed statistically significant difference from standard needle for overall and for every separate stroke length ( p<0.001 for all). Standard needle and the cores taken with 33mm stroke length of the end-cut needle had similar low fragmentation rates while 13 and 23mm stroke lengths had higher rates. Of the overall cores taken by BioPince needle, 46/344 (13%) of the cores were shorter than 5mm and this was significantly higher than the standard needle with 3/344 cores less than 5mm ( p<0.001). The end-cut needle when used with the 33mm stroke length has improved the core length by 68% according to the standard side-notch needle.

CONCLUSIONS

Our results showed that the performance of the end-cut needle worsens with decreased stroke lengths. The end-cut needle showed high failure rates which necessitates new punctures for taking a core. Additionally, the fragmentation rates are not lower than the standard needle and it has higher rates of taking small core samples. The only significant advantage of this needle over the standard needle is taking longer cores when it has been used at 33mm stroke lengths.

Morbidity of transrectal ultrasonography-guided prostate biopsies in patients after the continued use of low-dose aspirin

OBJECTIVE

To determine whether low-dose aspirin increases morbidity after transrectal ultrasonography-guided sextant prostate biopsy.

PATIENTS AND METHODS

In a single-centre prospective cohort study of 200 patients who underwent sextant prostate biopsies, those routinely taking low-dose aspirin were encouraged to continue to do so before and after biopsy. The morbidity in each case was assessed using a standardized questionnaire that patients completed in the 7 days after biopsy. The presence of haematuria, rectal bleeding and haematospermia were recorded. The questionnaire also directed the patient to record fevers, use of analgesia and any further treatment received.

RESULTS

In all, 36 patients took aspirin whilst the other 141 did not. There were no major complications in either group. Of the patients on aspirin, 20 (56%) had haematuria, compared with 83 (59%) of those not taking aspirin (difference 3%, 95% confidence interval, CI, -15 to 21). Overall bleeding (haematuria, rectal bleeding and haematospermia) occurred in 22 patients (61%) of the aspirin group and 105 (74%) of the other group (difference 13%, 95% CI -4 to 31). Comparisons of other morbidities between the groups are also discussed.

CONCLUSIONS

There was no statistically significant difference in the incidence of haematuria or overall bleeding after biopsy between the groups. There is no evidence that aspirin needs to be discontinued before sextant prostate biopsy.