Minimally invasive surgical approaches and management of prostate cancer

An inverse problem approach to recovery of in vivo nanoparticle concentrations from thermal image monitoring of MR-guided laser induced thermal therapy

Quantification of local variations in the optical properties of tumor tissue introduced by the presence of gold-silica nanoparticles (NP) presents significant opportunities in monitoring and control of NP-mediated laser induced thermal therapy (LITT) procedures. Finite element methods of inverse parameter recovery constrained by a Pennes bioheat transfer model were applied to estimate the optical parameters. Magnetic resonance temperature imaging (MRTI) acquired during a NP-mediated LITT of a canine transmissible venereal tumor in brain was used in the presented statistical inverse problem formulation. The maximum likelihood (ML) value of the optical parameters illustrated a marked change in the periphery of the tumor corresponding with the expected location of NP and area of selective heating observed on MRTI. Parameter recovery information became increasingly difficult to infer in distal regions of tissue where photon fluence had been significantly attenuated. Finite element temperature predictions using the ML parameter values obtained from the solution of the inverse problem are able to reproduce the NP selective heating within 5 °C of measured MRTI estimations along selected temperature profiles. Results indicate the ML solution found is able to sufficiently reproduce the selectivity of the NP mediated laser induced heating and therefore the ML solution is likely to return useful optical parameters within the region of significant laser fluence.

Contemporary referral pattern for robotic prostatectomy

The referral pattern for robotic-assisted laparoscopic prostatectomy suggests a growing acceptance of robotic surgery among urologists.

Background and Objectives:

In spite of the current widespread application of robotic surgery in the treatment of prostate cancer, it remains unclear whether current patterns of use are based on patient benefit or driven by marketing. We sought to investigate this possibility by analyzing the source of our patient population for robot-assisted laparoscopic prostatectomy (RALP).

Methods:

We reviewed 200 consecutive patients who underwent robotic prostatectomy by a single surgeon (RA) at our institution. The source of referral for each patient was analyzed along with individual patient characteristics to identify whether only low-risk or unusually ideal candidates were referred.

Results:

Of the 200 patients, 90.5% were referred by a urologist with only 5.5% being referred by another urologist at our institution. Only 10 patients cited media or marketing sources as the reason for self-referral, and <10 were referred by primary care physicians or other acquaintances. This referral pattern did not change between the first and second 100 patients. Referred patients included those up to 80 years of age, up to 51kg/m² in body mass index, and up to Gleason 9 on biopsy, with 36% of those referred by urologists having some history of previous abdominal or prostate surgery.

Conclusion:

The referral pattern for RALP at our institution may reflect a growing acceptance of robotic surgery among urologists in our region and is unlikely driven by patient-directed marketing. Additionally, urologists may also be more confident in the role of RALP as evidenced by their referral of even complex and higher-risk patients.

Magnetic resonance guided, focal laser induced interstitial thermal therapy in a canine prostate model

PURPOSE

We evaluated a newly Food and Drug Administration cleared, closed loop, magnetic resonance guided laser induced interstitial thermal therapy system for targeted ablation of prostate tissue to assess the feasibility of targeting, real-time monitoring and predicting lesion generation in the magnetic resonance environment.

MATERIALS AND METHODS

Seven mongrel dogs (University of Texas Health Science Center, Houston, Texas) with (2) and without (5) canine transmissible venereal tumors in the prostate were imaged with a 1.5 T magnetic resonance imaging scanner. Real-time 3-dimensional magnetic resonance imaging was used to accurately position water cooled, 980 nm laser applicators to predetermined targets in the canine prostate. Destruction of targeted tissue was guided by real-time magnetic resonance temperature imaging to precisely control thermal ablation. Magnetic resonance predictions of thermal damage were correlated with posttreatment imaging results and compared to histopathology findings.

RESULTS

Template based targeting using magnetic resonance guidance allowed the laser applicator to be placed within a mean ± SD of 1.1 ± 0.7 mm of the target site. Mean width and length of the ablation zone on magnetic resonance imaging were 13.7 ± 1.3 and 19.0 ± 4.2 mm, respectively, using single and compound exposures. The damage predicted by magnetic resonance based thermal damage calculations correlated with the damage on posttreatment imaging with a slope near unity and excellent correlation (r(2) = 0.94).

CONCLUSIONS

This laser induced interstitial thermal therapy system provided rapid, localized tissue heating under magnetic resonance temperature imaging control. Combined with real-time monitoring and template based planning, magnetic resonance guided, laser induced interstitial thermal therapy is an attractive modality for prostate cancer focal therapy.

Application of continuous tension to aid in performing the vesicourethral anastomosis for robot-assisted prostatectomy

OBJECTIVES

Approximation of the bladder to urethra during robot-assisted laparoscopic prostatectomy (RALP) is a critical step toward achieving long-term continence. To determine the impact on surgical outcomes after RALP, we compare two techniques for constructing the vesicourethral anastomosis.

METHODS

One hundred fifty-four men underwent RALP by one surgeon between 2005 and 2007. The vesicourethral anastomosis was performed in a standard Van Velthoven fashion for the first 61 patients. The anastomosis in the remaining 93 patients was performed in a running fashion with the sutures under continuous tension applied by the surgical assistant and the third robotic arm. Operative times and surgical outcomes were recorded prospectively.

RESULTS

When comparing standard Van Velthoven to continuous tension anastomosis, we demonstrate equivalent oncologic outcomes, continence and time required for the anastomosis. Yet, the frequency of complications related to the anastomotic technique, such as urine leaks, bladder neck contractures and migrated hemo-lock clips, were significantly lower with the continuous tension technique compared to the standard Van Velthoven running anastomosis.

CONCLUSIONS

Performing the vesicourethral anastomosis under continuous tension demonstrated improved outcomes compared to the Van Velthoven anastomosis by allowing persistent close apposition of the bladder to urethra. Additionally, the learning curve associated with implementation of a new anastomotic technique was negligible.

Technologies for localization and diagnosis of prostate cancer

The gold standard for detecting prostate cancer (PCa), systematic biopsy, lacks sensitivity as well as grading accuracy. PSA screening leads to over-treatment of many men, and it is unclear whether screening reduces PCa mortality. This review provides an understanding of the difficulties of localizing and diagnosing PCa. It summarizes recent developments of ultrasound (including elastography) and MRI, and discusses some alternative experimental techniques, such as resonance sensor technology and vibrational spectroscopy. A comparison between the different methods is presented. It is concluded that new ultrasound techniques are promising for targeted biopsy procedures, in order to detect more clinically significant cancers while reducing the number of cores. MRI advances are very promising, but MRI remains expensive and MR-guided biopsy is complex. Resonance sensor technology and vibrational spectroscopy have shown promising results in vitro. There is a need for large prospective multicentre trials that unambiguously prove the clinical benefits of these new techniques.

The current status of robot-assisted radical prostatectomy

Robot-assisted radical prostatectomy (RARP) is a rapidly evolving technique for the treatment of localized prostate cancer. In the United States, over 65% of radical prostatectomies are robot-assisted, although the acceptance of this technology in Europe and the rest of the world has been somewhat slower. This article reviews the current literature on RARP with regard to oncological, continence and potency outcomes-the so-called 'trifecta'. Preliminary data appear to show an advantage of RARP over open prostatectomy, with reduced blood loss, decreased pain, early mobilization, shorter hospital stay and lower margin rates. Most studies show good postoperative continence and potency with RARP; however, this needs to be viewed in the context of the paucity of randomized data available in the literature. There is no definitive evidence to show an advantage over standard laparoscopy, but the fact that this technique has reached parity with laparoscopy within 5 years is encouraging. Finally, evolving techniques of single-port robotic prostatectomy, laser-guided robotics, catheter-free prostatectomy and image-guided robotics are discussed.