Therapeutic prostate cancer interventions: a systematic review on pubic arch interference and needle positioning errors.

INTRODUCTION: This study focuses on the quantification of and current guidelines on the hazards related to needle positioning in prostate cancer treatment: (1) access restrictions to the prostate gland by the pubic arch, so-called Pubic Arch Interference (PAI) and (2) needle positioning errors. Next, we propose solution strategies to mitigate these hazards. METHODS: The literature search was executed in the Embase, Medline ALL, Web of Science Core Collection*, and Cochrane Central Register of Controlled Trials databases. RESULTS: The literature search resulted in 50 included articles. PAI was reported in patients with various prostate volumes. The level of reported PAI varied between 0 and 22.3 mm, depending on the patient's position and the measuring method. Low-Dose-Rate Brachytherapy induced the largest reported misplacement errors, especially in the cranio-caudal direction (up to 10 mm) and the largest displacement errors were reported for High-Dose-Rate Brachytherapy in the cranio-caudal direction (up to 47 mm), generally increasing over time. CONCLUSIONS: Current clinical guidelines related to prostate volume, needle positioning accuracy, and maximum allowable PAI are ambiguous, and compliance in the clinical setting differs between institutions. Solutions, such as steerable needles, assist in mitigating the hazards and potentially allow the physician to proceed with the procedure.This systematic review was performed in accordance with the PRISMA guidelines. The review was registered at Protocols.io (DOI: dx.doi.org/10.17504/protocols.io.6qpvr89eplmk/v1).

Combined Pubic Arch and Ischial Bone Resection for Metachronous and Frequent Local Recurrences of Rectal Cancer.

BACKGROUND/AIM: Complete surgical resection with negative margins remains the cornerstone for curative treatment of rectal cancer; however, local recurrence can pose a significant challenge. Herein, we aimed to introduce a novel surgical technique for combined resection of the pubic arch and ischial bone in the context of treating recurrent rectal cancer. CASE REPORT: We present a case of a patient with a fourth local recurrence of rectal cancer, with no evidence of distant metastasis. The tumor directly invaded the posterior wall of the pubic arch. To achieve complete tumor resection, an osteotomy was performed using a thread wire saw at the bilateral pubic rami and ischial bones. Intraoperative frozen section analysis (rapid tissue examination) was conducted on tissue samples from the lateral margins of the planned osteotomy line. Samples were negative for adenocarcinoma (cancerous cells). The combined resection of the pubic arch and ischial bone was successfully performed with negative margins for adenocarcinoma, as confirmed by frozen section analysis. CONCLUSION: Mastery of the surgical technique for combined resection of the pubic arch and ischial bone may be clinically significant for achieving complete resection in cases of multiple resections for locally recurrent rectal cancer.

Dosimetric benefits and preclinical performance of steerable needles in HDR prostate brachytherapy.

Prostate cancer patients with an enlarged prostate and/or excessive pubic arch interference (PAI) are generally considered non-eligible for high-dose-rate (HDR) brachytherapy (BT). Steerable needles have been developed to make these patients eligible again. This study aims to validate the dosimetric impact and performance of steerable needles within the conventional clinical setting. HDR BT treatment plans were generated, needle implantations were performed in a prostate phantom, with prostate volume > 55 cm3 and excessive PAI of 10 mm, and pre- and post-implant dosimetry were compared considering the dosimetric constraints: prostate V100 > 95 % (13.50 Gy), urethra D0.1cm3 < 115 % (15.53 Gy) and rectum D1cm3 < 75 % (10.13 Gy). The inclusion of steerable needles resulted in a notable enhancement of the dose distribution and prostate V100 compared to treatment plans exclusively employing rigid needles to address PAI. Furthermore, the steerable needle plan demonstrated better agreement between pre- and post-implant dosimetry (prostate V100: 96.24 % vs. 93.74 %) compared to the rigid needle plans (79.13 % vs. 72.86 % and 87.70 % vs. 81.76 %), with no major changes in the clinical workflow and no changes in the clinical set-up. The steerable needle approach allows for more flexibility in needle positioning, ensuring a highly conformal dose distribution, and hence, HDR BT is a feasible treatment option again for prostate cancer patients with an enlarged prostate and/or excessive PAI.

Overcoming pubic arch interference in prostate brachytherapy using steerable needles.

Purpose: A proportion of patients are not directly eligible for prostate brachytherapy (BT) due to pubic arch interference (PAI). Constraints in positioning sources behind the pubic arch due to linear, horizontal needle paths, may hamper effective irradiation of the target volume. This work evaluated the effect of prostate volume (Vp) and patient posture change on the amount of PAI, and demonstrated that steerable needles may broaden the inclusion criteria for patients with enlarged prostates and observed PAI. Material and methods: Twenty-seven patients (Vp > 60 cc) were included in this study. Access obstruction to the prostate was evaluated using diagnostic magnetic resonance imaging (MRI) scans, after six upward rotations of the pelvis and the prostate in 5 degree steps, to indicate the effect of patient posture change from supine to lithotomy position. For patients with PAI, we evaluated if the steerable needle could access the obstructed volume of the prostate. Results: The data showed no clear relation between Vp and PAI. In 23 of the 27 patients, in which PAI was observed, 14 showed obstruction of the prostate of ≥ 10 mm in the supine position (mean PAI ± standard deviation: 15.2 ±3.8 mm). Anatomical rotation reduced PAI by 4.8 mm after every 10 degrees of upward rotation, still resulting in obstructions of 8.1 ±2.4 mm in 10 of the 14 cases after 15 degree rotation. The steerable needle enabled access to all the required coordinates of the prostate. Conclusions: The ability to steer along curved paths enables prostate BT in patients with enlarged prostates and PAI, and reduces the change of needing to abandon treatment.

Sonographic risk assessment for an unplanned operative delivery: a prospective study.

PURPOSE: To assess the value of pre-labor maternal and fetal sonographic variables to predict an unplanned operative delivery. METHODS: In this prospective study, nulliparous women were recruited at 37.0-42.0 weeks of gestation. Sonographic measurements included estimated fetal weight, maternal pubic arch angle, and the angle of progression. We performed a descriptive and comparative analysis between two outcome groups: spontaneous vaginal delivery (SVD) and unplanned operative delivery (UOD) (vacuum-assisted, forceps-assisted and cesarean deliveries). Multivariate logistic regression with ROC analysis was used to create discriminatory models for UOD. RESULTS: Among 234 patients in the study group, 175 had a spontaneous vaginal delivery and 59 an unplanned operative delivery. Maternal height and pubic arch angle (PAA) significantly correlated with UOD. Analysis of Maximum Likelihood Estimates revealed a multivariate model for the prediction of UOD, including the parameters of maternal age, maternal height, sonographic PAA, angle of progression (AOP), and estimated fetal weight, with an area under the curve of 0.7118. CONCLUSION: Sonographic parameters representing maternal pelvic configuration (PAA) and maternal-fetal interface (AOP) improve the prediction ability of pre-labor models for a UOD. These data may aid the obstetrician in the counseling process before delivery.

Steering a Tendon-Driven Needle in High-Dose-Rate Prostate Brachytherapy for Patients with Pubic Arch Interference.

High-dose-rate brachytherapy (HDR BT) is a radiation therapy that places radioactive sources at cancerous tissue using needles. HDR BT offers better dose conformality and sparing of clinical structures, lower operator dependency, and fewer acute irritative symptoms compared to the other form of BT (low-dose-rate (LDR)). However, use of HDR BT is limited for patients with pubic arch interference, where the transperineal path to the prostate is blocked. This study aims to introduce a tendon-driven needle that can bend inside tissue to reach desired positions inside prostate. Initial experiments in a phantom tissue showed the feasibility of the needle to get around the pubic arch for placement at hard-to-reach target positions.

Improving the Degree of Pubic Arch Post-Yoga Exercise During Pregnancy.

Yoga exercises undertaken during the maternity period may reduce unpleasant symptoms during pregnancy and reduce delivery pain. Flexibility of the hip joint improves the degree of pubic arch created in an open-leg posture and widens the pelvic outlet region, shortening the time required for delivery and facilitating easy delivery. The degree of pubic arch is related to the flexibility of the hip joint. Although many studies have shown the effect of yoga exercise during pregnancy, the effect on the degree of the pubic arch has not been elucidated. To elucidate whether the degree of the pubic arch is improved by yoga exercise during pregnancy, this study enrolled 177 pregnant subjects. The degree of pubic arch pre- and post-yoga exercise was measured using instruments in an open-leg posture (seated with femurs abducted). The mean pubic arch pre- and post-yoga was 122.61 and 127.93 degrees, respectively. The degree of pubic arch post-yoga sessions was significantly increased compared with pre-yoga sessions (p < 0.01). This study showed that yoga exercises during the pregnancy period appear to improve the degree of pubic arch.

The birth canal: correlation between the pubic arch angle, the interspinous diameter, and the obstetrical conjugate: a computed tomography biometric study in reproductive age women.

Background: Assessment of pelvic configuration is an important factor in the prediction of a successful vaginal birth. However, manual evaluation of the pelvis is practically a vanishing art, and imaging techniques are not available as a real-time bed-side tool. Unlike the obstetrical conjugate diameter (OC) and inter spinous diameter (ISD), the pubic arch angle (PAA) can be easily measured by transperineal ultrasound. Objectives: Three-dimensional computed tomography bone reconstructions were used to measure the three main birth canal diameters, evaluate the correlation between them, and establish the normal reference range for the inlet, mid-, and pelvic outlet. Study design: Measurements of the PAA, obstetric conjugate (OC), and ISD were performed offline using three-dimensional post processing reconstruction in bone algorithm application of the pelvis on examinations performed for suspected renal colic in nonpregnant reproductive age woman. The mean of two measurements was used for statistical analysis which included reproducibility of measurements, regression curve estimation between PAA, OC, and ISD, and calculation of the respective reference range centiles for each PAA degree. Results: Two hundred ninety-eight women comprised the study group. The mean ± SD of the PAA, ISD, and OC were 104.9° (±7.4), 103.8 mm (±7.3), and 129.9 mm (±8.3), respectively. The intra- and interobserver agreement defined by the intraclass correlation coefficient (ICC) was excellent for all parameters (range 0.905-0.993). A significant positive correlation was found between PAA and ISD and between PAA and OCD (Pearson's correlation = 0.373 (p < .001), and 0.163 (p = .022), respectively). The best regression formula was found with quadratic regression for inter spinous diameter (ISD): 34.122778 + (0.962182*PAA - 0.002830*PAA2), and linear regression for obstetric conjugate (OC): 110.638397 + 0.183156*PAA. Modeled mean, SD, and reference centiles of the ISD and OCD were calculated using the above regression models as function of the PAA. Conclusions: We report significant correlation between the three pelvic landmarks with greatest impact on the prediction of a successful vaginal delivery: the PAA which is easily measured sonographically and the ISD and OC which are not measurable by ultrasound. This correlation may serve as a basis for future studies to assess its utility and prognostic value for a safe vaginal delivery.

Predicting pubic arch interference in permanent prostate brachytherapy based on the specific parameters derived from nuclear magnetic resonance imaging.

PURPOSE: The aim of this study was to establish a more reliable method to predict pubic arch interference (PAI) before permanent prostate brachytherapy. MATERIAL AND METHODS: We retrospectively analyzed the nuclear magnetic resonance imaging (MRI) results of forty patients with prostate cancer, who were treated with permanent implantation of 125I seeds (permanent brachytherapy). We measured and calculated six parameters based on the MRI results: 1. The prostate volume (PV); 2. The angle of the pubic arch (AoPA); 3. The angle of PAI (AoPAI, pubic symphysis level); 4. The height of PAI (hPAI, pubic symphysis level); 5. The maximum angle of PAI (AoPAIMax); 6. The maximum height of PAI (hPAIMax). We then tested which parameters could accurately predict PAI through receiver operating characteristic (ROC) curve analysis. RESULTS: The results of this study demonstrated that AoPAI, hPAI, hPAIMax, and AoPAIMax could predict PAI. Out of forty cases in our research, 10 cases were with PAI and 30 cases without PAI during the operation. The areas under the ROC curve for PV, AoPA, AoPAI (pubic symphysis level), hPAI (pubic symphysis level), AoPAIMax, and hPAIMax were 0.592, 0.567, 0.957, 0.940, 0.927, and 0.877, respectively. The AoPAI (pubic symphysis level), hPAI (pubic symphysis level), AoPAIMax, and hPAIMax were statistically correlated with PAI. The boundary values were 26.32°, 1.13 cm, 28.37°, and 1.51 cm, respectively. CONCLUSIONS: This new method derived from MRI has predictive value, as AoPAI, hPAI, hPAIMax, and AoPAIMax could predict PAI. Taking other factors into consideration, we suggest the use of AoPAI as a novel and very reliable predictor of PAI.

Permanent prostate brachytherapy pubic arch evaluation with diagnostic magnetic resonance imaging.

PURPOSE: Pubic arch interference (PAI), when it occurs, is often a limiting factor for patients pursuing brachytherapy treatment of prostate cancer. Pre-brachytherapy pubic arch evaluation is often performed by CT or transrectal ultrasound (TRUS), but MRI has increasingly replaced these modalities for prostate cancer evaluation. The purpose of this study was to determine if staging MRI could be used to evaluate PAI and compare it with these other imaging methods. METHODS AND MATERIALS: Forty-one consecutive patients undergoing brachytherapy evaluation had pelvic MRI-, CT-, and TRUS-based brachytherapy simulation. Pubic arch overlap on T2-weighted MRI and CT was determined by contouring the prostate gland on its largest axial slice and superimposing this contour onto the pubic arch bones. The largest degree of overlap of the prostate gland on MRI and CT was used to predict the existence of PAI as determined by TRUS-based simulation. The correlation between prostate contour overlap was also compared between MRI and CT. RESULTS: Nineteen patients (48%) exhibited PAI on TRUS brachytherapy simulation evaluation. The average (±standard error) amount of prostate contour overlap on the pubic arch on CT was 2.9 ± 0.6 mm and on MRI was 2.0 ± 0.6 mm (linear correlation, R, of 0.783, p < 0.001). CT and MRI were equally predictive of PAI on TRUS evaluation (area under the curve = 0.75). CONCLUSION: Pre-brachytherapy pubic arch assessment with diagnostic MRI provides similar predictability of PAI compared with CT, potentially obviating the need for additional pre-brachytherapy CT in the setting of staging MRI.

Variability of the pubic arch architecture and its influence on the minimal levator hiatus area.

OBJECTIVE: To investigate the association between the minimal levator hiatus (MLH) area at rest with its surrounding soft-tissue and bony structures in nulliparous asymptomatic women with a normal levator ani muscle. METHODS: A subanalysis was undertaken of a prospective study of the appearance of the levator ani in asymptomatic nulliparous women conducted between September 2010 and September 2011. The subanalysis included women with a normal levator ani muscle. Three-dimensional ultrasonography volumes were used to obtain pelvic floor measurements. RESULTS: The analysis included 56 women with mean age of 43.0±13.4years. The mean MLH area was 13.1±1.8cm(2) (range 9.0-17.3). The pubic arch angle had no influence on the MLH area (Pearson correlation coefficient r=0.13). Height and pubic arch length were positively correlated with the MLH area (r=0.26 [P=0.52] and r=0.50 [P<0.001], respectively). CONCLUSION: The MLH size of nulliparous women varied widely and was positively correlated with the height and pubic arch length of the women. Therefore, caution is warranted when interpreting the MLH area as an indicator of a levator ani defect or a predictor of pelvic organ prolapse without taking a woman's pelvic bone characteristics into account.