Laser Interstitial Thermotherapy Research Articles

Histologic findings associated with laser interstitial thermotherapy for glioblastoma multiforme

BackgroundLaser-interstitial thermal therapy (LITT) has been supported by some authors as an ablative treatment of glioblastoma multiforme (GBM). Although the effects of LITT have been modeled in vivo, the histologic effects in a clinical circumstance have not been described. We analyzed tissue from a patient who underwent LITT as primary treatment for GBM.Case presentationA 62-year-old male was diagnosed with a left temporal GBM and underwent LITT at an outside institution. Despite corticosteroid therapy, the patient was referred with increasing headache and acalculia associated with progressive peritumoral edema two weeks after LITT procedure. En bloc resection of the enhancing lesion and adjacent temporal lobe was performed with steroid-independent symptom resolution (follow-up, > 2 years). Histologic analysis revealed three distinct histologic zones concentrically radiating from the center of the treatment site. An acellular central region of necrosis (Zone 1) was surrounded by a rim of granulation tissue with macrophages (CD68) (Zone 2; mean thickness, 1.3 ± 0.3 mm [±S.D.]). Viable tumor cells (identified by Ki-67, p53 and Olig2 immunohistochemistry) were found (Zone 3) immediately adjacent to granulation tissue. The histologic volume of thermal tissue ablation/granulation was consistent with preoperative (pre-resection) magnetic resonance (MR)-imaging.ConclusionThese findings are the first in vivo in humans to reveal that LITT causes a defined pattern of tissue necrosis, concentric destruction of tumor and tissue with viable tumor cells just beyond the zones of central necrosis and granulation. Furthermore, MR-imaging appears to be an accurate surrogate of tissue/tumor ablation in the early period (2 weeks) post-LITT treatment. Surgery is an effective strategy for patients with post-LITT swelling which does not respond to steroids.

Improved MR thermometry for laser interstitial thermotherapy.

To develop, test and evaluate improved 2D and 3D protocols for proton resonance frequency shift magnetic resonance temperature imaging (MRTI) of laser interstitial thermal therapy (LITT). The objective was to develop improved MRTI protocols in terms of temperature measurement precision and volume coverage compared to the 2D MRTI protocol currently used with a commercially available LITT system. Four different 2D protocols and four different 3D protocols were investigated. The 2D protocols used multi-echo readouts to prolong the total MR sampling time and hence the MRTI precision, without prolonging the total acquisition time. The 3D protocols provided volumetric thermometry by acquiring a slab of 12 contiguous slices in the same acquisition time as the 2D protocols. The study only considered readily available pulse sequences (Cartesian 2D and 3D gradient recalled echo and echo planar imaging [EPI]) and methods (partial Fourier and parallel imaging) to ensure wide availability and rapid clinical implementation across vendors and field strengths. In vivo volunteer studies were performed to investigate and compare MRTI precision and image quality. Phantom experiments with LITT heating were performed to investigate and compare MRTI precision and accuracy. Different coil setups were used in the in vivo studies to assess precision differences between using local (such as flex and head coils) and non-local (i.e., body coil) receive coils. Studies were performed at both 1.5 T and 3 T. The improved 2D protocols provide up to a factor of two improvement in the MRTI precision in the same acquisition time, compared to the currently used clinical protocol. The 3D echo planar imaging protocols provide comparable precision as the currently used 2D clinical protocol, but over a substantially larger field of view, without increasing the acquisition time. As expected, local receive coils perform substantially better than the body coil, and 3 T provides better MRTI accuracy and precision than 1.5 T. 3D data can be zero-filled interpolated in all three dimensions (as opposed to just two dimensions for 2D data), reducing partial volume effects and measuring higher maximum temperature rises. With the presented protocols substantially improved MRTI precision (for 2D imaging) or greatly improved field of view coverage (for 3D imaging) can be achieved in the same acquisition time as the currently used protocol. Only widely available pulse sequences and acquisition methods were investigated, which should ensure quick translation to the clinic. Lasers Surg. Med. 51:286-300, 2019. © 2019 Wiley Periodicals, Inc.

Epigastric Paresthesia: Can It Be This Serious?

Intoduction: Paresthesia is an abnormal sensation caused by an altered sensory pathway anywhere from the peripheral nervous system up to the sensory cortex. Epigastric paresthesia is an unusual presentation that sometimes warrants an extensive workup to rule out any gastrointestinal pathology. In our patient the result of the workup was unexpected. Case Summary: A 58-year-old male with a history of hypertension and diabetes presented to the hospital with epigastric numbness and warmth sensation of 2 weeks duration. His numbness episodes were sudden, lasting 2-3 minutes, starting in the epigastric area, then spreading to the whole abdomen and extremities. These episodes were associated with nausea and vomiting but no abdominal pain, diarrhea or constipation. A Computed Tomography (CT) scans of the head, abdomen and pelvis were negative. Esophagogastroduodenoscopy (EGD) was negative for any pathology. Due to the suspicion of seizures, an Electroencephalogram (EEG) was done and showed spikes consistent with seizure tendency. A Magnetic Resonance Imaging (MRI) of the brain showed focal asymmetric enlargement of the left posterior medial temporal lobe with inhomogeneous mass enhancement concerning for a neoplasm (Figure 1-A, 2-A). A multi-disciplinary discussion including neurology, neurosurgery, and oncology thought that the MRI findings were secondary to enhancement from seizures, but the neoplastic process was not excluded. Patient was discharged on Levetiracetam 750 mg BID, with a scheduled MRI in 4 weeks. The repeat MRI showed increasing size and enhancement of the lesion concerning for a primary brain tumor (Figure 1-B, 2-B). As a result, a stereotactic needle biopsy and laser interstitial thermotherapy were performed, and the pathology showed high-grade glioma. His post-operative course was unremarkable, and he was discharged to follow up with neuro-oncology and neurosurgery. Conclusion: Epigastric paresthesia is a rare presentation, and when it is associated with GI upset it warrants a workup to rule out any GI pathology. Given the seriousness of the diagnosis in our patient, primary brain tumor should be considered with patients presenting with abdominal paresthesia.2477_A Figure 1. A: Brain mass at first presentation B: Brain mass 4 weeks later2477_B Figure 2. A: Brain mass at first presentation B: Brain mass 4 weeks later

Techniques to Ensure Accurate Targeting for Delivery of Awake Laser Interstitial Thermotherapy.

Magnetic resonance imaging (MRI) guided laser interstitial thermal therapy (LITT) is an emerging neurosurgical treatment modality that is typically performed under general anesthesia. We describe a novel workflow developed at the University of Florida to deliver LITT in conscious patients without the use of general anesthesia. To describe a novel workflow for LITT implementation in the awake patient with equivalent treatment results when compared to procedures performed under general anesthesia. For trajectories near a post of the Cosman-Roberts-Wells (CRW) frame (Integra LifeSciences, Plainsboro, New Jersey), we used preoperative MRI imaging to 3-dimensional-print a patient-specific mask with a trajectory guide to indicate the planned entry point during headframe placement. Otherwise, routine headframe placement and stereotactic registration were performed. Stereotactic biopsy and placement of the cranial bolt were performed in a standard neurosurgical operating room. The patient was transferred to a diagnostic MRI suite and positioned in the MRI scanner using beanbags and a custom molded thermoplastic mask. LITT was delivered with the patient conscious in the MRI scanner according to the manufacturer's recommendations. We collected patient demographics, treatment time, length of stay, and calculated preoperative tumor volume and postoperative ablation volumes. Ten sequential patients were treated with LITT from January 2016 until March 2017. The average preoperative tumor volume was 6.9 cm3. The average tissue volume ablated was 18.3 cm3. The mean operative time was 31 min (standard deviation [SD] 10 min) and mean time with laser delivery in MRI was 79 min (SD 27 min). The mean length of stay was 1.4 d (SD 0.9). There were no major complications. Using trajectory preplanning, customized face masks, and noninvasive head immobilization, LITT can be delivered to patients safely and accurately without general anesthesia.

Phase I/II study of laser interstitial thermotherapy (LITT) combined with checkpoint inhibitor for recurrent glioblastoma (rGBM).

TPS2074Background: Glioblastoma (GBM) has a survival of only 3-5 months at recurrence.. Salvage chemotherapy has been largely ineffective with PFS-6 rates of 10-15%. Bevacizumab's impact on OS is m...

Laser interstitial thermotherapy (LITT) for newly diagnosed and recurrent glioblastoma: Safety, effectiveness and association between time to initiation of chemotherapy postprocedure and outcome (P4.155)

Laser interstitial thermotherapy (LITT) for newly diagnosed and recurrent glioblastoma: Safety, effectiveness and association between time to initiation of chemotherapy postprocedure and outcome (P4.155)

Applications of a robotic stereotactic arm for pediatric epilepsy and neurooncology surgery.

OBJECTIVE The ROSA device is a robotic stereotactic arm that uses a laser system to register the patient's head or spine with MR or CT images. In this study, the authors analyze their experience with this system in pediatric neurosurgical applications and present selected cases that exemplify the usefulness of this system. METHODS The authors reviewed all cases that utilized the ROSA system at their institution. Patient demographics, pathology, complications, electrode placement, laser ablation, and biopsy accuracy were analyzed. Patient disposition and condition at follow-up were also analyzed. RESULTS Seventeen patients underwent 23 procedures using the ROSA system. A total of 87 electroencephalography electrodes were placed, with 13% deviating more than 3 mm from target. Six patients underwent stereotactic needle biopsy, and 9 underwent laser interstitial thermotherapy (LITT). One patient who underwent LITT required a subsequent craniotomy for tumor resection. Another patient experienced an asymptomatic extraaxial hematoma that spontaneously resolved. No patient suffered neurological complications during follow-up. Follow-up from the last procedure averaged 180 days in epilepsy patients and 309 days in oncology patients. CONCLUSIONS The precision, ease of use, and versatility of the ROSA system make it well suited for pediatric neurosurgical practice. Further work, including long-term analysis of results and cost-effectiveness, will help determine the utility of this system and if its applications can be expanded.

Minimally Invasive Robotic Laser Corpus Callosotomy: A Proof of Concept.

IntroductionWe describe the feasibility of using minimally invasive robotic laser interstitial thermotherapy (LITT) for achieving an anterior two-thirds as well as a complete corpus callosotomy.MethodsTen probe trajectories were plotted on normal magentic resonance imaging (MRI) scans using the Brainlab Stereotactic Planning Software (Brainlab, Munich, Germany). The NeuroBlate® System (Monteris Medical, MN, USA) was used to conform the thermal burn to the corpus callosum along the trajectory of the probe. The distance of the ideal entry site from either the coronal suture and the torcula or nasion and the midline was calculated. The distance of the probe tip from the dorsal and ventral limits of the callosotomy in the sagittal plane were also calculated.ResultsAnterior two-thirds callosotomy was possible in all patients using a posterior parieto-occipital paramedian trajectory through the non-dominant lobe. The average entry point was 3.64 cm from the midline, 10.6 cm behind the coronal suture, and 9.2 cm above the torcula. The probe tip was an average of 1.4 cm from the anterior commissure. For a total callosotomy, an additional contralaterally placed frontal probe was used to target the posterior one-third of the corpus callosum. The average entry site was 3.3 cm from the midline and 9.1 cm above the nasion. The average distance of the probe tip from the base of the splenium was 0.94 cm.ConclusionThe directional thermoablation capability of the NeuroBlate® system allows for targeted lesioning of the corpus callosum, to achieve a two-thirds or complete corpus callosotomy. A laser distance of < 2 cm is sufficient to reach the entire corpus callosum through one trajectory for an anterior two-thirds callosotomy and two trajectories for a complete callosotomy.

Spinal Laser Interstitial Thermal Therapy: A Novel Alternative to Surgery for Metastatic Epidural Spinal Cord Compression.

Although surgery followed by radiation effectively treats metastatic epidural compression, the ideal surgical approach should enable fast recovery and rapid institution of radiation and systemic therapy directed at the primary tumor. To assess spinal laser interstitial thermotherapy (SLITT) as an alternative to surgery monitored in real time by thermal magnetic resonance (MR) images. Patients referred for spinal metastasis without motor deficits underwent MR-guided SLITT, followed by stereotactic radiosurgery. Clinical and radiological data were gathered prospectively, according to routine practice. MR imaging-guided SLITT was performed on 19 patients with metastatic epidural compression. No procedures were discontinued because of technical difficulties, and no permanent neurological injuries occurred. The median follow-up duration was 28 weeks (range 10-64 weeks). Systemic therapy was not interrupted to perform the procedures. The mean preoperative visual analog scale scores of 4.72 (SD ± 0.67) decreased to 2.56 (SD ± 0.71, P = .043) at 1 month and remained improved from baseline at 3.25 (SD ± 0.75, P = .021) 3 months after the procedure. The preoperative mean EQ-5D index for quality of life was 0.67 (SD ± 0.07) and remained without significant change at 1 month 0.79 (SD ± 0.06, P = .317) and improved at 3 months 0.83 (SD ± 0.06, P = .04) after SLITT. Follow-up MR imaging after 2 months revealed significant decompression of the neural component in 16 patients. However, 3 patients showed progression at follow-up, 1 was treated with surgical decompression and stabilization and 2 were treated with repeated SLITT. MR-guided SLITT can be both a feasible and safe alternative to separation surgery in carefully selected cases of spinal metastatic tumor epidural compression. cEBRT, conventional external beam radiation therapyESCC, epidural spinal cord compressionSLITT, spinal laser interstitial thermotherapySSRS, stereotactic spinal radiosurgeryVAS, visual analog scale.

Laser Ablation of Newly Diagnosed Malignant Gliomas: a Meta-Analysis.

Magnetic resonance-guided laser-interstitial thermotherapy (MR-LITT) is a minimally invasive technique that shows promise in neuro-oncology because of its superiority in delivering precise minimally invasive thermal energy with minimal collateral damage. In this analysis, we investigate initial data on the use of MR-LITT in the treatment of newly diagnosed high-grade gliomas. With the use of the PubMed, OVID, and Google-scholar database systems, a comprehensive search of the English literature was performed. Eighty-five articles were identified plus 1 that is pending publication. Four articles were accounted for in this review, including 25 patients with newly diagnosed high-grade gliomas who underwent MR-LITT treatment. We evaluated safety, progression-free survival, and overall survival. Twenty-five patients with a mean age of 53.8 years underwent LITT treatments. On average, 82.9% of the pretreatment lesion volume was ablated. The average tumor volume treated was 16.5 cm. The mean follow-up time was 7.6 months. Median overall survival was found to be 14.2 months (range 0.1-23 months). The median progression-free survival was 5.1 months (range 2.4-23 months); however, these data are limited by the relatively short follow-up of the patients reviewed and small sample size of only 25 patients. There was 1 (3.4%) major perioperative complication, which was a central nervous system infection. MR-LITT is a promising technology for the treatment of small, yet difficult-to-treat newly diagnosed high-grade gliomas. This study demonstrates that MR-LITT is safe, and future randomized studies are needed to evaluate its role as a treatment adjunct for newly diagnosed high-grade gliomas. BBB, blood-brain barrierHGG, high-grade gliomaLITT, laser-interstitial thermal therapyWHO, World Health Organization.

The use of custom 3D printed stereotactic frames for laser interstitial thermal ablation: technical note.

Over the last several years, laser interstitial thermotherapy (LITT) has gained wide acceptance for the treatment of a myriad of cranial lesions. A wide variety of techniques for placement of the laser fiber have been reported with a spectrum of perceived benefits and drawbacks. The authors present the first report of a customized 3D printed stereotactic frame for LITT. Approximately 1 week prior to surgery, 3-4 skull fiducials were placed after each of 5 patients received a local anesthetic as an outpatient. Radiographs with these fiducials were then used to create a trajectory to the lesion that would be treated with LITT. After the plan was completed, software was used to render a customized frame. On the day of surgery, the frame was attached to the implanted skull fiducials and the LITT catheter was placed. This procedure was carried out in 5 consecutive patients. In 2 patients, a needle biopsy was also performed. Intraoperative and postoperative imaging studies confirmed the accurate placement of the LITT catheter and the lesion created. Mean operating room time for all patients was 45 minutes but only 26 minutes when excluding the cases in which a biopsy was performed. To the best of the authors' knowledge, this is the first report of the use of a specific system, the STarFix microTargeting system, for use with LITT and brain biopsy. This system offers several advantages including fast operating times, extensive preoperative planning, no need for cranial fixation, and no need for frame or fiducial placement on the day of surgery. The accuracy of the system combined with these advantages may make this a preferred stereotactic method for LITT, especially in centers where LITT is performed in a diagnostic MRI suite.

Percutaneous surgery for treatment of epidural spinal cord compression and spinal instability: technical note.

OBJECTIVE An emerging paradigm for treating patients with epidural spinal cord compression (ESCC) caused by metastatic tumors is surgical decompression and stabilization, followed by stereotactic radiosurgery. In the setting of rapid progressive disease, interruption or delay in return to systemic treatment can lead to a negative impact in overall survival. To overcome this limitation, the authors introduce the use of spinal laser interstitial thermotherapy (sLITT) in association with percutaneous spinal stabilization to facilitate a rapid return to oncological treatment. METHODS The authors retrospectively reviewed a consecutive series of patients with ESCC and spinal instability who were considered to be poor surgical candidates and instead were treated with sLITT and percutaneous spinal stabilization. Demographic data, Spine Instability Neoplastic Scale score, degree of epidural compression before and after the procedure, length of hospital stay, and time to return to oncological treatment were analyzed. RESULTS Eight patients were treated with thermal ablation and percutaneous spinal stabilization. The primary tumors included melanoma (n = 3), lung (n = 3), thyroid (n = 1), and renal cell carcinoma (n = 1). The median Karnofsky Performance Scale score before and after the procedure was 60, and the median hospital stay was 5 days (range 3-18 days). The median Spine Instability Neoplastic Scale score was 13 (range 12-16). The mean modified postoperative ESCC score (2.75 ± 0.37) was significantly lower than the preoperative score (4.5 ± 0.27) (Mann-Whitney test, p = 0.0044). The median time to return to oncological treatment was 5 days (range 3-10 days). CONCLUSIONS The authors present the first cohort of sLITT associated with a percutaneous spinal stabilization for the treatment of ESCC and spinal instability. This minimally invasive technique can allow a faster recovery without prejudice of adjuvant systemic treatment, with adequate local control and spinal stabilization.

Advancements in Stereotactic Epilepsy Surgery: Stereo-EEG, Laser Interstitial Thermotherapy, and Responsive Neurostimulation

Advancements in Stereotactic Epilepsy Surgery: Stereo-EEG, Laser Interstitial Thermotherapy, and Responsive Neurostimulation

Optical fiber solutions for laser ablation of tissue and immunostimulating interstitial laser thermotherapy – Product development in the network of developers, industry and users

Abstract: Clinical Laserthermia Systems AB (CLS) has developed a treatment protocol named immunostimulating interstitial laser thermotherapy (imILTCLS) which is intended to improve current treatment regimens for metastatic cancer diseases. It aims at a controlled local tumor ablation with a subsequent release of tumor specific antigens resulting in a systemic immune activation against the remaining cancer cells. The approach has its origins in the laser-induced interstitial thermotherapy procedure and is based on a proprietary and patented technique to optimize the immunological effect. CLS has gained know-how through long experience both in clinical and pre-clinical studies of the application, laser technology, thermometry, and expertise in regulatory affairs. However, CLS does not have the in-house expertise required for fiber development and production. Therefore the company has actively searched for industrial partners to collaborate with on the design and development of a fiber delivery system tailored to imILTCLS. The aim of this collaboration is to design an application-specific laser fiber that allows the treatment of a wider range of tumors with a single treatment and overcomes the limitations of currently available laser fibers, such as the limited achievable lesion sizes due the maximum power that can be used without carbonizing tissue. The present contribution gives a short overview about the current development steps within the network of developers, industry and users.

The use of image guided laser interstitial thermotherapy to supplement spine stereotactic radiosurgery to manage metastatic epidural spinal cord compression: Proof of concept and dosimetric analysis

Spine stereotactic radiosurgery (SSRS) is a form of stereotactic body radiation therapy by which advanced treatment delivery techniques (eg, intensity modulated radiotherapy) are combined with image guidance and rigid immobilization to deliver a high dose of conformal radiation to the target while minimizing dose to nearby critical structures such as the spinal cord. For well-selected patients, SSRS offers durable local control1 and pain relief.2 However, patients with epidural disease continue to pose a clinical treatment challenge. Patterns of failure analyses have shown a predilection for failure in the epidural space.3 Given that the spinal cord dose restrictions take precedence over tumor coverage, cases with epidural extension generally have suboptimal dose delivery to the gross tumor volume (GTV). Improved local control with single-fraction SSRS has correlated with dosimetric factors such as the

Neurosurgical Techniques for Disruption of the Blood-Brain Barrier for Glioblastoma Treatment.

The blood–brain barrier remains a main hurdle to drug delivery to the brain. The prognosis of glioblastoma remains grim despite current multimodal medical management. We review neurosurgical technologies that disrupt the blood–brain barrier (BBB). We will review superselective intra-arterial mannitol infusion, focused ultrasound, laser interstitial thermotherapy, and non-thermal irreversible electroporation (NTIRE). These technologies can lead to transient BBB and blood–brain tumor barrier disruption and allow for the potential of more effective local drug delivery. Animal studies and preliminary clinical trials show promise for achieving this goal.

Utilization of laser interstitial thermotherapy guided by real-time thermal MRI as an alternative to separation surgery in the management of spinal metastasis.

High-grade malignant spinal cord compression is commonly managed with a combination of surgery aimed at removing the epidural tumor, followed by spinal stereotactic radiosurgery (SSRS) aimed at local tumor control. The authors here introduce the use of spinal laser interstitial thermotherapy (SLITT) as an alternative to surgery prior to SSRS. Patients with a high degree of epidural malignant compression due to radioresistant tumors were selected for study. Visual analog scale (VAS) scores for pain and quality of life were obtained before and within 30 and 60 days after treatment. A laser probe was percutaneously placed in the epidural space. Real-time thermal MRI was used to monitor tissue damage in the region of interest. All patients received postoperative SSRS. The maximum thickness of the epidural tumor was measured, and the degree of epidural spinal cord compression (ESCC) was scored in pre- and postprocedure MRI. In the 11 patients eligible for study, the mean VAS score for pain decreased from 6.18 in the preoperative period to 4.27 within 30 days and 2.8 within 60 days after the procedure. A similar VAS interrogating the percentage of quality of life demonstrated improvement from 60% preoperatively to 70% within both 30 and 60 days after treatment. Imaging follow-up 2 months after the procedure demonstrated a significant reduction in the mean thickness of the epidural tumor from 8.82 mm (95% CI 7.38-10.25) before treatment to 6.36 mm (95% CI 4.65-8.07) after SLITT and SSRS (p = 0.0001). The median preoperative ESCC Grade 2 was scored as 4, which was significantly higher than the score of 2 for Grade 1b (p = 0.04) on imaging follow-up 2 months after the procedure. The authors present the first report on an innovative minimally invasive alternative to surgery in the management of spinal metastasis. In their early experience, SLITT has provided local control with low morbidity and improvement in both pain and the quality of life of patients.

Establishment of C6 brain glioma models through stereotactic technique for laser interstitial thermotherapy research.

Objective:To establish C6 brain glioma models using stereotactic technique, and to study effects of laser interstitial thermotherapy (LITT) in rat models of glioma.Methods:C6 glioma cells were cultured in dulbecco's minimum essential medium (DMEM) cell culture medium. The in vitro C6 cell cultures were stereotaxically implanted into the right caudate nucleus of rat brain. Presence of tumor was confirmed with Factor VIII R, hematoxylin–eosin stain, staining of glial fibrillary acid protein, and S-100 immunohistochemistry. After magnetic resonance (MR) scanning and correction of tumor location, the models were divided into groups according to the treating time and laser power (2–10 W). Semiconductor laser optical fibers were inserted in tumors for LITT. Cortex's temperature conducted from the center target was measured using infrared thermograph, and deep-tissue temperature around the target was measured using a thermocouple.Results:Rat C6 gliomas were inoculated with optimized stereotactic technique. These gliomas resembled human glioma in terms of histopathological features. Such models are more reliable and reproducible, with 100% yield of intracranial tumor and no extracranial growth extension. The difference between cortex temperature conducted from center target and deep-tissue temperature around target was not statistically significant.Conclusion:The rat C6 brain glioma model established in the study was a perfect model to study LITT of glioma. Infrared thermograph technique measured temperature conveniently and effectively. The technique is noninvasive, and the obtained data could be further processed using software used in LITT research. To measure deep-tissue temperature, combining thermocouple with infrared thermograph technique would present better results.

Quantitative identification of magnetic resonance imaging features of prostate cancer response following laser ablation and radical prostatectomy.

Laser interstitial thermotherapy (LITT) is a relatively new focal therapy technique for the ablation of localized prostate cancer. In this study, for the first time, we are integrating ex vivo pathology and magnetic resonance imaging (MRI) to assess the imaging characteristics of prostate cancer and treatment changes following LITT. Via a unique clinical trial, which gave us the availability of ex vivo histology and pre- and post-LITT MRIs, (1)we investigated the imaging characteristics of treatment effects and residual disease, and (2)evaluated treatment-induced feature changes in the ablated area relative to the residual disease. First, a pathologist annotated the ablated area and the residual disease on the ex vivo histology. Subsequently, we transferred the annotations to the post-LITT MRI using a semi-automatic elastic registration. The pre- and post-LITT MRIs were registered and features were extracted. A scoring metric based on the change in median pre- and post-LITT feature values was introduced, which allowed us to identify the most treatment responsive features. Our results show that (1)image characteristics for treatment effects and residual disease are different, and (2)the change of feature values between pre- and post-LITT MRIs can be a quantitative biomarker for treatment response. Finally, using feature change improved discrimination between the residual disease and treatment effects.

Prostate changes related to therapy: with special reference to hormone therapy.

Hormone and radiation therapy have traditionally been used in prostate cancer (PCa). Morphological effects are often identified in needle biopsies and surgical specimens. A range of histological changes are seen in the non-neoplastic prostate and in the pre-neoplastic and neoplastic areas. Other ablative therapies, including cryotherapy, and emerging focal therapies, such as high-intensity focused ultrasound, photodynamic therapy and interstitial laser thermotherapy, may induce changes on the prostate. As new compounds are developed for prostate cancer treatment, it is important to document their effects on benign and neoplastic prostate tissue.