Minimally invasive therapies for benign prostatic hyperplasia in the new millennium: long-term data

Outcomes of prostate artery embolisation for benign prostatic hyperplasia in 10 cases at Steve Biko Academic Hospital

Background

Benign prostate hyperplasia (BPH) remains a common cause of lower urinary tract symptoms (LUTS) in ageing men in South Africa and can impact significantly on the quality of life (QOL) of these patients. The Urology Department at Steve Biko Academic Hospital (SBAH) can generally only offer men with LUTS the following treatment options: watchful waiting, medical treatment and surgical management. In men with symptomatic BPH, who are refractory to medical treatment, where anaesthesia is contra-indicated because of co-morbidities or transurethral resection of the prostate (TURP) is contra-indicated because of the prostate size, the Urology and Radiology departments at SBAH recently introduced prostate artery embolisation (PAE).

Aim

To assess the outcome of PAE in 10 men with LUTS, secondary to BPH, by comparing their urinary symptoms, QOL and prostate volume before and 3 months after they underwent PAE in the Radiology Department at SBAH.

Method

The review included the first 10 men who had undergone therapeutic PAE for symptomatic BPH from May 2016 to September 2016. The subjective symptomatic feedback was assessed according to the International Prostate Symptom Score (IPSS) and the Global Quality of Life questionnaire, created by the American Urological Association (AUA). The reduction in the size of the prostate was measured on magnetic resonance imaging (MRI).

Results

Embolisation was technically achieved in all 10 patients. Bilateral embolisation was performed on nine patients. One patient received unilateral embolisation secondary to unilateral tortuous and atherosclerotic changes of the iliac arteries. Within the 3-month follow-up, the mean IPSS score improved by 15.7 points (p < 0.0039), the mean QOL improved by 4.1 points (p < 0.0039) and the mean prostate volume reduction was 21.8 mL (p < 0.0039). Despite improvements observed, there was one clinical failure. No major complications were reported that increased hospital stay, required hospital readmission or required surgery.

Conclusion

The study on the first 10 PAE performed in SBAH concludes that PAE is a safe and effective procedure with favourable short-term follow-up results. This indicates that PAE can safely be offered to patients, who are refractory to medical treatment and not suitable candidates for surgery, in urology departments such as in SBAH.

Evaluation of outcome of transurethral needle ablation for treating symptomatic benign prostatic hyperplasia: A 10-year experience

Aim:

The aim of this study is to report our 10-year experience with transurethral needle ablation (TUNA) to evaluate its outcome on long-term basis.

Patients and Methods:

A total of 351 patients’ records who underwent TUNA procedure for the management of benign prostatic hyperplasia were reviewed. The International Prostate Symptom Score (IPSS) and peak urinary flow rate were evaluated before the procedure, at 3 and 6 months postoperatively, and then yearly for 10 years. For patients complaining of de novo erectile dysfunction, the International Index of Erectile Function-5 was evaluated. Postoperative complications, number of patients who required additional therapeutic modality/other TUNA sessions, or those dropped out during follow-up were all recorded.

Results:

Three hundred and fifty-one patients who underwent TUNA with fulfillment of our selection criteria were included in the study. The yearly records of included patients showed that patients’ baseline IPSS was significantly improved all over the follow-up years. Similarly, the maximum flow rate of the patients was significantly improved during the next 8 years. About 96.4% of patients who underwent TUNA did not require additional therapeutic modality/other TUNA sessions during the 1^st-year follow-up. However, by 10 years, 26.4% of patients were offered another TUNA session and shifted to either medical therapy or other minimally invasive therapies. Mild hematuria was the most common complication (85.7%). Urinary retention, urethral stricture, and de novo erectile dysfunction were developed in 15.1%, 1.7%, and 6.8% of patients, respectively. There were no cases of retrograde ejaculation.

Conclusion:

TUNA can be considered as a relatively effective technique with a good safety profile. The current study demonstrated both significant subjective and objective improvements over 10 and 8 years of follow-up, respectively. It can be considered as a preferable option for patients who prefer surgical option with preservation of their sexual function and fertility.

Thermal ablation and high-temperature thermal therapy: Overview of technology and clinical implementation

High-temperature hyperthermia or thermal therapy is being applied for destruction of cancerous tissue, eradication or reduction of benign tumours and targeted tissue modification and remodelling. Many of these high-temperature technologies provide a minimally-invasive alternative with lower morbidities compared to the traditional surgical procedures. The effects of high-temperature thermal exposure on tissues, examples of heating technology and procedures of clinical practice related to high-temperature thermal therapy are reviewed. This brief review encompasses interstitial, endocavity, intraluminal and external applications of RF, microwave, ultrasound, laser and thermal conduction energy sources. The technology is prevalent and in various levels of advancement, with the move toward more spatially-accurate and controllable heating systems combined with image-guidance and treatment verification warranted, especially for the treatment of cancer.

High-performance system GreenLight laser: indications and outcomes

PURPOSE OF REVIEW

In this review, we present recent clinical and urodynamic data on transurethral photoselective vaporization of the prostate, and report on the recent introduction of the 120 W GreenLight laser (GLL) high-performance system.

RECENT FINDINGS

Published studies provide substantial evidence that photoselective prostate vaporization is an efficacious treatment for lower urinary tract symptoms caused by benign prostatic hyperplasia. Recent studies confirm improved urodynamic findings following GLL treatment. Moreover, it can be used safely in high-risk patients (e.g. those on anticoagulant medication and patients with cardiopulmonary diseases), and has been proposed as an alternative to prostate enucleation for larger glands. Depending on the reimbursement system in different countries, it can be a cost-effective procedure. The introduction of the 120 W high-performance system GLL does, however, place distinct demands on training and operative schemes.

SUMMARY

The clinical results of GreenLight prostate vaporization are equivalent to those following transurethral resection of the prostate, with reduced operative risks, even for the high-risk patient. These clinical benefits have been confirmed by improved urodynamic parameters. The potential advantages of the new 120 W high-performance system GLL are yet to be unequivocally proven in larger randomized trials.

Transurethral ultrasound applicators with dynamic multi-sector control for prostate thermal therapy: in vivo evaluation under MR guidance

The purpose of this study was to explore the feasibility and performance of a multi-sectored tubular array transurethral ultrasound applicator for prostate thermal therapy, with potential to provide dynamic angular and length control of heating under MR guidance without mechanical movement of the applicator. Test configurations were fabricated, incorporating a linear array of two multi-sectored tubular transducers (7.8-8.4 MHz, 3 mm OD, 6 mm length), with three 120 degrees independent active sectors per tube. A flexible delivery catheter facilitated water cooling (100 ml min(-1)) within an expandable urethral balloon (35 mm long x 10 mm diameter). An integrated positioning hub allows for rotating and translating the transducer assembly within the urethral balloon for final targeting prior to therapy delivery. Rotational beam plots indicate approximately 90 degrees-100 degrees acoustic output patterns from each 120 degrees transducer sector, negligible coupling between sectors, and acoustic efficiencies between 41% and 53%. Experiments were performed within in vivo canine prostate (n = 3), with real-time MR temperature monitoring in either the axial or coronal planes to facilitate control of the heating profiles and provide thermal dosimetry for performance assessment. Gross inspection of serial sections of treated prostate, exposed to TTC (triphenyl tetrazolium chloride) tissue viability stain, allowed for direct assessment of the extent of thermal coagulation. These devices created large contiguous thermal lesions (defined by 52 degrees C maximum temperature, t43 = 240 min thermal dose contours, and TTC tissue sections) that extended radially from the applicator toward the border of the prostate (approximately15 mm) during a short power application (approximately 8-16 W per active sector, 8-15 min), with approximately 200 degrees or 360 degrees sector coagulation demonstrated depending upon the activation scheme. Analysis of transient temperature profiles indicated progression of lethal temperature and thermal dose contours initially centered on each sector that coalesced within approximately 5 min to produce uniform and contiguous zones of thermal destruction between sectors, with smooth outer boundaries and continued radial propagation in time. The dimension of the coagulation zone along the applicator was well-defined by positioning and active array length. Although not as precise as rotating planar and curvilinear devices currently under development for MR-guided procedures, advantages of these multi-sectored transurethral applicators include a flexible delivery catheter and that mechanical manipulation of the device using rotational motors is not required during therapy. This multi-sectored tubular array transurethral ultrasound technology has demonstrated potential for relatively fast and reasonably conformal targeting of prostate volumes suitable for the minimally invasive treatment of BPH and cancer under MR guidance, with further development warranted.

Greenlight Prostatectomy: A Challenge to the Gold Standard?

The use of lasers to carry out resection of the prostate gland is an ever-evolving field which has seen several different modalities of laser light used with varying success. This review looks at what makes the traditional transurethral resection of prostate the gold standard and provides the evidence on the evolution of the laser prostatectomy in trying to usurp it as the favored procedure for symptomatic benign prostatic hyperplasia. In particular, we show how the latest laser technology in the form of the Greenlight laser is challenging not only other lasers such as the holmium laser, but may form a strong contender to replace the transurethral resection of prostate.

Numerical Simulation of a BPH Thermal Therapy—A Case Study Involving TUMT

The use of numerical simulation as a means to predict the outcome of transurethral microwave thermotherapy (TUMT) is set forth in detail. The simulation was carried out as a case study of a specific TUMT procedure. The selection of the case study was based on the availability of extensive medical records which documented an extraordinary application of TUMT. Predictions were made of the time-varying temperature patterns within the prostate, the bladder, the sphincter, the pelvic floor, and the fat and connective tissue which envelop these organs. These temperature patterns provided the basis of maps which highlighted those locations where necrosis occurred. An injury integral was used to predict the extent of the necrotic tissue produced by the therapy. It was found that, for the specific case being considered, necrosis occurred not only within the prostate but also extended to the neck of the bladder and to the fatty tissue. A special feature of the simulation was the accounting of the liquid-to-vapor phase change of the interstitial water. The vapor generated by the phase change is believed to significantly enlarge the region of necrosis. By the same token, the vapor pressure is expected to cause motion of the high-temperature liquid to deep-tissue regions. The damage predicted by the numerical simulation was compared, in detail, with post-operative medical examinations and found to be corroborated.

How do I treat and follow my TUNA patients

Transurethral needle ablation (TUNA) of the prostate is an alternative treatment for benign prostatic hyperplasia (BPH) generating temperatures around 100 degrees C leading to necrotic lesions inside the prostate. TUNA is a minimally invasive, low morbidity associated, approach that uses radiofrequency energy. The needles are covered by teflon shields that protect the urethra from thermal injury. Since the introduction of TUNA, there has been a constant upgrading of the device to improve treatment quality. The main advantage of this therapy is the possibility of an outpatient care due to its anaesthesia-free option with a prostatic block. Catheterisation after the procedure is required in 10-40% of cases. Long-term data (5 years) on TUNA demonstrate a sustained improvement of both IPSS score and urinary flow. About a quarter of patients require further intervention at 5 years' follow-up. The safety profile, along with the significant improvement in both objective and subjective parameters observed after TUNA, makes it an attractive approach for symptomatic BPH.

Medical and minimally invasive therapies for the treatment of benign prostatic hyperplasia

Over the last decade, management of benign prostatic hyperplasia (BPH) has changed with a substantial decrease in the use of transurethral prostatectomy (TURP) and a simultaneous increase in the use of medical therapy and minimally invasive surgical therapy (MIST). The goal of management of this chronic progressive condition is not only to provide relief of lower urinary tract symptoms (LUTS) but also to reduce the lifetime risk of adverse outcomes. Recent clinical evidence has demonstrated a clear role for medical therapy, particularly with 5-alpha-reductase inhibitors (5ARIs) either alone or in combination with alpha-blockers, to reduce the risk of acute urinary retention and need for surgery and provide symptom relief. Clinical data on MISTs also indicate a more pronounced short-term effect; however, the long-term durability of these therapies remains uncertain. Minimally invasive surgical therapies confer treatment benefits in a single 1-h treatment session under local anesthesia. Recovery times and adverse events are improved compared with TURP, but issues such as hematuria, prolonged catheterization, urinary tract infection and retreatment remain commonly reported issues. Today, urologists are faced with the challenge of identifying the most appropriate treatment option for the long-term management of BPH. The initial choice for any given patient will depend on his presenting circumstances and the influence of treatment risks on these circumstances. Providing patients with informed treatment decisions is a key element of management.

Electro-sensitisation of mammalian cells and tissues to ultrasound: a novel tumour treatment modality

This study demonstrates that mammalian cell targets (erythrocytes and tumour cells) may be sensitised to ultrasound using electric pulses and this combination treatment results in destruction of those cells in vitro. It further demonstrates that when a tumour mass is treated in vivo using combined electric field and ultrasound therapy, significant retardation of tumour growth has been observed using a mouse tumour model. We suggest that combined electric field and ultrasound (CEFUS) therapy may provide a novel, drug-free treatment modality for cancer.

Catheter-based ultrasound applicators for selective thermal ablation: progress towards MRI-guided applications in prostate

High-temperature thermal therapy is emerging as a feasible treatment option for prostate cancer and benign prostatic hyperplasia. Previous investigations have demonstrated distinct advantages of catheter-based ultrasound technology over other heating modalities for thermal ablation therapies, with significant potential for better spatial control and faster heating times. The purpose of this study was to develop ultrasound devices and techniques specifically for treating prostate cancer in conjunction with magnetic resonance thermal imaging (MRTI) to monitor and control treatment progression. Directional transurethral applicators have been designed with arrays of sectored tubular (90 degrees active acoustic sector) or with narrow planar transducer segments and integrated with a flexible delivery catheter with a cooling balloon. This applicator can be rotated within the prostatic urethra to target specific regions during treatment. MRI compatible catheter-cooled interstitial ultrasound applicators with 180 degrees active acoustic sectors were developed specifically to treat the prostate. These applicators may be implanted through the perineum into the posterior portion of the prostate, with their heating energy directed away from the rectum. Both heating strategies were evaluated via biothermal simulations and in vivo experiments within canine prostate (n = 3). During the in vivo studies, MRTI was used to monitor treatment temperatures, cytotoxic thermal doses (t43 > 240 min) and corresponding maximum temperature thresholds (Tmax > 52 degrees C) within three imaging planes simultaneously. Urethral and endorectal cooling was employed with both treatment strategies to provide further protection of the urethral mucosa and rectum from thermal damage. Results using the transurethral applicators demonstrated that narrow zones of coagulation (approximately 30 degrees sector for planar, approximately 90 degrees for tubular), extending up to 20 mm from the urethra to the periphery of the prostate gland, could be produced within 10-15 min. Further, rotation of the applicator during treatment could be used to destroy larger regions in the prostate. Experiments using multiple interstitial directional applicators (approximately 180 degrees active sectors), implanted within the posterior margin of the prostate with the energy directed away from the rectum, produced contiguous zones of thermal coagulation which extended from the posterior prostate toward the anterior-lateral periphery of the gland. Both transurethral and interstitial treatment strategies demonstrated significant potential for thermal ablation of localized prostate cancer, particularly when MRTI is used to guide and assess treatment.

Ablation of canine prostate using two-stage intraprostatic hot agarose solution and enzyme injection

Enzyme ablation of the hyperplastic prostate may be an ideal method of management of BPH. However, the unsatisfactory ablation affects in vivo contrast with successful in vitro results limiting the enthusiasm for further research. In this study, we make efforts to solve the problems in the use of enzyme ablation of BPH in vivo and to measure satisfactory effect.

MATERIAL AND METHODS

A total of 18 hybrid dogs between the ages of 7 and 11 y underwent this experiment. Eight dogs were divided into four groups according to the injection formula: enzyme solution, hot D-Hanks' plus enzyme solution, hot agarose plus enzyme solution, and hot agarose solution alone. After selecting the agarose plus enzyme solution group in the first month, the remainder 10 dogs were treated with this two-stage method. Intravenous or oral antibiotics were administered perioperatively. All operations were performed directly by way of laparotomy. The prostates were observed and harvested with surrounding tissue at 24 hrs, 7 days, 14 days, 1 month and 3-5 months after treatment. Gross and microscopic examinations were performed.

RESULTS

Only agarose plus enzyme group shows obvious cavity formation with concomitant size reduction and softening of the prostate ablation effect in the four groups. At 24 h after injection, the prostates demonstrated cavity formation containing liquefied necrotic tissue. The liquefied tissue was absorbed in 7-14 days. At 1 month, the size of most prostates decreased with a corresponding decrease in the size of the cavities. The cavities nearly disappeared within 3-5 months, and the size of prostates decreased to between 1/2 and 1/4 of the pretreatment sizes. All prostates had intact urethral mucosa and capsule. No complications directly related to enzyme ablation were identified. In the control groups there were no significant cavities or decrease in prostate size.

CONCLUSIONS

This two-stage thermal and enzyme ablative method can significantly ablate prostate tissue without identifiable complications, and would be possibly applied to treating human BPH in the future.

Three-year follow-up of feedback microwave thermotherapy versus TURP for clinical BPH: A prospective randomized multicenter study

OBJECTIVES

To compare, in a prospective randomized multicenter study, the efficacy and safety of transurethral microwave thermotherapy with ProstaLund Feedback Treatment (PLFT), using the CoreTherm device, with transurethral resection of the prostate (TURP) 36 months after treatment.

METHODS

The study was conducted at 10 centers in the United States and Scandinavia. A total of 154 patients with benign prostatic hyperplasia were randomized to PLFT or TURP in a 2:1 ratio. The treatment outcome was evaluated on the basis of the International Prostate Symptom Score (IPSS), the quality-of-life question (QOL) of the IPSS, peak urinary flow rate (Qmax), urodynamics, and adverse events. The microwave power and treatment time were adjusted according to each patient's response to the supplied energy (ie, the intraprostatic temperature guided the PLFT).

RESULTS

Statistically significant improvements in both the TURP and the PLFT groups were observed for IPSS, QOL, and Qmax at 36 months. The average value for the PLFT group was 8.2, 1.2, and 11.9 mL/s for IPSS, QOL, and Qmax, respectively. The corresponding values for the TURP group were IPSS 5.0, QOL 1.0, and Qmax 13.5 mL/s. The difference in IPSS outcome was statistically significant; however, no statistically significant differences were found in QOL or Qmax between the two treatment groups. The degree of improvement was in the same range as that observed after 12 and 24 months for both groups. During the 12 to 36-month period, the most frequent adverse events in the TURP group were impotence (15%), micturition urgency (13%), and urethral disorder (8%); in the PLFT group, impotence (8%), prostate-specific antigen increase (5%), and hematuria (4%) were the most common.

CONCLUSIONS

The clinical outcome 3 years after microwave thermotherapy with PLFT was comparable to the results seen after TURP. The safety of PLFT compared favorably to that of TURP in this study.

Transurethral ultrasound applicators with directional heating patterns for prostate thermal therapy: in vivo evaluation using magnetic resonance thermometry

A catheter-based transurethral ultrasound applicator with angularly directional heating patterns has been designed for prostate thermal therapy and evaluated in canine prostate in vivo using MRI to monitor and assess performance. The ultrasound transducer array (3.5 mm diameter tubular transducers, 180 degrees active sectors, approximately 7.5 MHz) was integrated to a flexible delivery catheter (4 mm OD), and encapsulated within an expandable balloon (35 mm x 10 mm OD, 80 ml min(-1) ambient water) for coupling and cooling of the prostatic urethra. These devices were used to thermally coagulate targeted portions of the canine prostate (n = 2) while using MR thermal imaging (MRTI) to monitor the therapy. MRI was also used for target definition, positioning of the applicator, and evaluation of target viability post-therapy. MRTI was based upon the complex phase-difference mapping technique using an interleaved gradient echo-planar imaging sequence with lipid suppression. MRTI derived temperature distributions, thermal dose exposures, T1-contrast enhanced MR images, and histology of sectioned prostates were used to define destroyed tissue zones and characterize the three-dimensional heating patterns. The ultrasound applicators produced approximately 180 degrees directed zones of thermal coagulation within targeted tissue which extended 15-20 mm radially to the outer boundary of the prostate within 15 min. Transducer activation lengths of 17 mm and 24 mm produced contiguous zones of coagulation extending axially approximately 18 mm and approximately 25 mm from base to apex, respectively. Peak temperatures around 90 degrees C were measured, with approximately 50 degrees C-52 degrees C corresponding to outer boundary t43 = 240 min at approximately 15 min treatment time. These devices are MRI compatible, and when coupled with multiplanar MRTI provide a means for selectively controlling the length and sector angle of therapeutic thermal treatment in the prostate.

Highly directional transurethral ultrasound applicators with rotational control for MRI-guided prostatic thermal therapy

Transurethral ultrasound applicators with highly directional energy deposition and rotational control were investigated for precise treatment of benign prostatic hyperplasia (BPH) and adenocarcinoma of the prostate (CaP). Two types of catheter-based applicators were fabricated, using either 90 degrees sectored tubular (3.5 mm OD x 10 mm) or planar transducers (3.5 mm x 10 mm). They were constructed to be MRI compatible, minimally invasive and allow for manual rotation of the transducer array within a 10 mm cooling balloon. In vivo evaluations of the applicators were performed in canine prostates (n = 3) using MRI guidance (0.5 T interventional magnet). MR temperature imaging (MRTI) utilizing the proton resonance frequency shift method was used to acquire multiple-slice temperature overlays in real time for monitoring and guiding the thermal treatments. Post-treatment T1-weighted contrast-enhanced imaging and triphenyl tetrazolium chloride stained tissue sections were used to define regions of tissue coagulation. Single sonications with the 90 degrees tubular applicator (9-15 W, 12 min, 8 MHz) produced coagulated zones covering an 80 degrees wedge of the prostate extending from 1-2 mm outside the urethra to the outer boundary of the gland (16 mm radial coagulation). Single sonications with the planar applicator (15-20 W, 10 min, approximately 8 MHz) generated thermal lesions of approximately 30 degrees extending to the prostate boundary. Multiple sequential sonications (sweeping) of a planar applicator (12 W with eight rotations of 30 degrees each) demonstrated controllable coagulation of a 270 degrees contiguous section of the prostate extending to the capsule boundary. The feasibility of using highly directional transurethral ultrasound applicators with rotational capabilities to selectively coagulate regions of the prostate while monitoring and controlling the treatments with MRTI was demonstrated in this study.

Long-term evaluation of transurethral needle ablation of the prostate (TUNA) for treatment of symptomatic benign prostatic hyperplasia: clinical outcome up to five years from three centers

OBJECTIVE

TUNA has been demonstrated to be a safe and effective therapy for BPH. However the major criticism, as with all alternative treatments for BPH, was the lack of long-term data. We present the clinical outcome of patients treated by TUNA and followed for 5 years.

METHODS

188 consecutive patients with symptomatic BPH treated with TUNA were followed for five years in three different centers. All patients were treated using the TUNA II or TUNA III catheters under local anesthesia only without general or spinal anesthesia. Baseline and 5-year follow-up evaluation included urinary peak flow, International Prostate Symptom Score (IPSS) and post-void residual urine (PVR). The number of patients requiring additional medical or surgical treatment was recorded. Statistics were performed using the t-test.

RESULTS

At a mean follow-up of 63 months, mean urinary peak flow rate increased from 8.6 ml/s to 12.1 ml/s (p<0.01, t-test), IPSS and PVR decreased from 20.9 and 179 ml to 8.7 and 122 ml, respectively (both p<0.001, t-test). The percentage of patients who improved by at least 50% their peak uroflow and IPSS was 24% and 78% respectively. Mean prostate volume and PSA levels did not change significantly (53.9 cc vs. 53.8 cc and 3.3 vs. 3.6 ng/ml, respectively at 5 years, both p values > 0.05, t-test). Two patients died of unrelated comorbidities and 10 were lost for follow-up. Medical treatment was given to 12 patients (6.4%), a second TUNA performed in 7 patients (3.7%) and surgery indicated in 22/186 (11.1%). Overall 41/176 patients (188 at start, 2 deaths and 10 lost to follow-up) or 23.3% required additional treatment at 5 years follow-up following the original TUNA procedure.

CONCLUSIONS

TUNA is effective and provides good long-term clinical improvement at 5-year follow-up. TUNA treatment stands the test of time at 5-year follow-up with low and acceptable failure rates. More than 75% of the patients do not need additional treatment for BPH on the long run.

Normal human salivary gland cells produce carcinoembryonic antigen-related antigen in collagen gels

The Arrhenius and thermal isoeffective dose (TID) models are the two most commonly used models for predicting hyperthermic injury. The TID model is essentially derived from the Arrhenius model, but due to a variety of assumptions and simplifications now leads to different predictions, particularly at temperatures higher than 50°C. In the present study, the two models are compared and their appropriateness tested for predicting hyperthermic injury in both the traditional hyperthermia (usually, 43–50°C) and thermal surgery (or thermal therapy/thermal ablation, usually, >50°C) regime. The kinetic parameters of thermal injury in both models were obtained from the literature (or literature data), tabulated, and analyzed for various prostate and kidney systems. It was found that the kinetic parameters vary widely, and were particularly dependent on the cell or tissue type, injury assay used, and the time when the injury assessment was performed. In order to compare the capability of the two models for thermal injury prediction, thermal thresholds for complete killing (i.e., 99% cell or tissue injury) were predicted using the models in two important urologic systems, viz., the benign prostatic hyperplasia tissue and the normal porcine kidney tissue. The predictions of the two models matched well at temperatures below 50°C. At higher temperatures, however, the thermal thresholds predicted using the TID model with a constant R value of 0.5, the value commonly used in the traditional hyperthermia literature, are much lower than those predicted using the Arrhenius model. This suggests that traditional use of the TID model (i.e., R=0.5) is inappropriate for predicting hyperthermic injury in the thermal surgery regime (>50°C). Finally, the time-temperature relationships for complete killing (i.e., 99% injury) were calculated and analyzed using the Arrhenius model for the various prostate and kidney systems.