Prostate biopsy: targeting cancer for detection and therapy

Despite improvements in cancer detection, prostate biopsy still lacks the ability to accurately map locations of cancer within the prostate. Improvements in prostate imaging may allow more accurate mapping of overall disease volume. Magnetic resonance (MR) spectroscopy allows improved specificity in detecting even small foci of disease within the peripheral zone. Improvements in MR-guided biopsy techniques may allow this technology to be adapted to therapeutics as well. Computer modeling of individual prostates serves as a means of designing optimized plans for prostate biopsy. The use of novel targeted biopsy schemes may allow an integration of available technologies in detection and localization of prostate cancer. Computer-directed needle biopsies based on anatomic landmarks within the prostate and computerized three-dimensional reconstruction of the gland may allow a highly reproducible means of identifying small foci of cancer, targeting them for therapy, and monitoring for recurrence. The TargetScan(R) system (Envisioneering Medical Technologies, St. Louis, MO) is the first technology to integrate available targeting methodologies in a systematic fashion.     

Optimizing prostate biopsy strategies for the diagnosis of prostate cancer

The importance of prostate biopsy in urologic practice has been magnified by the routine use of serum prostate-specific antigen in prostate cancer screening. Given the potential impact of the procedure on both patient care and health care costs, an optimal strategy for accurate and judicious detection of early prostate cancer is imperative. Maintaining maximal sensitivity and negative predictive value are equally important to the patient. In this article, we review recent modifications in prostate biopsy indications and techniques that may allow for a systematic biopsy approach to the patient in whom prostate cancer is suspected.     

系统活检联合超声造影及弹性成像靶向活检在前列腺活检中的应用价值

摘要 目的：探讨系统活检联合超声造影及弹性成像靶向活检在前列腺活检中的应用价值。方法：回顾性分析2015年1月至2019年12月我院收治的394例可疑前列腺癌患者的临床资料。分为前期组（2015年1月至2017年4月,采用12针系统活检法,共186例）,和近期组（2017年5月至2019年12月,采用8针系统活检联合新技术（超声造影及弹性成像）靶向活检法,共208例）。前期组行12+X针系统穿刺活检。近期组患者先行彩虹灌注及实时弹性成像检查,确定可疑区域后,于该区域行靶向穿刺活检,然后行8针系统穿刺活检,有重复区域者适当减少穿刺针数。结果：近期组阳性患者99例;前期组阳性患者63例,前列腺癌检出率分别为47.6%（99/208）、33.87%（63/186）,差异具有统计学意义（P<0.05）;近期组与前期组总穿刺针数分别为1929、2200针,近期组平均9.0 1.8针,前期组平均11.8 1.6针,差异具有统计学意义（P<0.05）;近期组与前期组穿刺针数阳性率分别为23.89%（461/1929）、11.82%（260/2200）,差异具有统计学意义（P<0.05）;近期组与前期组并发症发生率分别为27.40%（57/208）、43.01%（80/186）,差异具有统计学意义（P<0.05）。结论：系统活检联合超声造影及弹性成像靶向活检对前列腺癌具有较高应用价值。     

Evaluation of ultrasonography effectiveness in prostate cancer detection

The database of examining 624 patients aged 49-85 were analyzed to define the diagnostic effectiveness of gray-scale, color and power Doppler transrectal ultrasonography (TRUS). Among them there are 473 (75.8%) cancer patients and 151 (24.2%) benign prostate diseases patients. All the patients underwent a transrectal ultrasound examination with multifocal biopsy. The gray-scale, color and power Doppler transrectal ultrasound examination has the diagnostic accuracy of 75,3%. At this the effectiveness of the method increases with the Gleason sum growing.     

Ultrasound-Guided Percutaneous Renal Biopsy in 295 Children and Adolescents: Role of Ultrasound and Analysis of Complications

Introduction

Percutaneous renal biopsy (PRB) is a decisive diagnostic procedure for children and adolescents with renal diseases. Aim of this study was to evaluate retrospectively the complication rates of percutaneous kidney biopsies and their therapeutic consequences to assess the role of ultrasound-guidance including Doppler ultrasound examinations in preparation, execution and follow-up care and to present a recommended protocol.

Patients and Methods

Institutional review board approved this retrospective study; informed consent was waived. Between 1997 and 2011 a total of 438 ultrasound-guided biopsies were performed in 295 patients, 169 of the biopsies were performed on kidney transplants. Average age of patients was 10.2+/−5.2 years (range of 15 days until age of 23). Before and post biopsy ultrasound examination including Doppler examination was carried out. Biopsy itself was ultrasound monitored. Complications were analysed with regard to age of patient, kidney transplants, year of occurrence, number of punctures, performing physician and time interval of occurrence to develop an optimized protocol for ultrasound-guidance.

Results

In 99% of cases successful PRB were performed, i.e. enough kidney parenchyma for histological analysis was obtained. No lethal or major complication that required surgical intervention occurred. Eighteen relevant complications were observed (complication rate: 4.1%). Except in one case in which additional MRI diagnostic was necessary, ultrasound examination after 4 hours post biopsy or even earlier when symptoms occurred, was able to detect complications and determine indications for intervention.

Conclusion

Ultrasound-guided PRB is an established and effective method in children and adolescents, but shows a certain rate of complications and therefore should not be indicated without diligence. Ultrasound including Doppler ultrasound is a valuable tool in preparation, guidance of biopsy, detection of complications and in follow-up care. Ultrasound examinations (including Doppler) pre-, during and 4 hours post kidney biopsy and, depending from case, a few days until weeks after biopsy is recommended.     

Prostate cancer: risk assessment and diagnostic approaches

The successful treatment of prostate cancer relies on detection of the disease at its earliest stages. Although prostate-specific antigen (PSA)-based screening has been a significant advance in the early diagnosis of prostate cancer, identifying specific genetic alterations in a given family or patient will allow more appropriate screening for early disease. Mapping and identification of specific prostate cancer susceptibility genes is slowly becoming a reality. Other prostate cancer risks include a family history, race, and possibly serum markers such as insulin-like growth factor-I (IGF-I). Once a high-risk man is identified, transrectal ultrasound (TRUS)-guided biopsies are the standard to diagnose prostate cancer. Although TRUS is an advance over traditional digitally directed biopsies, it represents a random sampling of the prostate since most lesions cannot be visualized. Newer modalities such as ultrasound contrast agents, pattern recognition, and artificial neural networks (ANNs), applied to TRUS images, may improve diagnostic accuracy. If a man at risk for prostate cancer has undergone a negative TRUS biopsy, the decision for the need for additional biopsies is problematic. Use of PSA derivatives such as free and total PSA and the initial biopsy abnormalities such as atypia or high-grade prostatic intraepithelial neoplasia may define those patients in need of follow-up biopsy.     

MR thermometry characterization of a hyperthermia ultrasound array designed using the k-space computational method

Background  

Ultrasound induced hyperthermia is a useful adjuvant to radiation therapy in the treatment of prostate cancer. A uniform thermal dose (43°C for 30 minutes) is required within the targeted cancerous volume for effective therapy. This requires specific ultrasound phased array design and appropriate thermometry method. Inhomogeneous, acoustical, three-dimensional (3D) prostate models and economical computational methods provide necessary tools to predict the appropriate shape of hyperthermia phased arrays for better focusing. This research utilizes the k-space computational method and a 3D human prostate model to design an intracavitary ultrasound probe for hyperthermia treatment of prostate cancer. Evaluation of the probe includes ex vivo and in vivo controlled hyperthermia experiments using the noninvasive magnetic resonance imaging (MRI) thermometry.     

Transrectal sonography in prostate cancer detection--our 25 years experience of implementation

Prostate cancer is a leading public health problem of male population in developed countries. Gold standard for prostate cancer diagnosis is true cut biopsy guided by transrectal ultrasound. Aim of this study was to determine sensitivity, specificity, accuracy, positive and negative predictive value of transrectal sonography (TRUS) in prostate cancer detection. The analysis was made for two time periods, before and after routine implementation of prostate specific antigen (PSA) in prostate cancer diagnostics. From 1984 to 1993 TRUS guided prostate biopsy was performed in 564, and from 1994 to 2008 in 5678 patients. In the second period PSA was routinely used in prostate cancer diagnostics. In the first period by TRUS we have made an exact diagnosis of prostate cancer in 18.97% of patients what was confirmed by biopsy. 4.61% ware false positive and 11.34% ware false negative. In the second period prostate cancer was recognized in 30.34% of patients, confirmed by biopsy. False positive cases ware 6.11% and false negative 29.31%. Sensitivity of transrectal sonography in the first period was 62.57%, specificity 94.2%, accuracy 86.2%, positive predictive value 80.45% and negative predictive value 87.72%. In the second period sensitivity was 50.87%, specificity 91.93%, accuracy 73.84%, positive predictive value 83.24% and negative predictive value 70.39%. Based on our experience we can conclude that prostate cancer is mostly found in the peripheral zone. Smaller tumors are hypoechoic and bigger tumors are hyperechoic. Prostate cancer lesions are impossible to differentiate from chronic prostatitis only by TRUS. Implementation of PSA has significantly decrease sensitivity, accuracy and negative predictive value of TRUS in prostate cancer detection. TRUS guided true cut biopsy is a gold standard in prostate cancer diagnostics.     

Imaging in the diagnosis and management of prostate cancer

The current diagnosis and management of prostate cancer is largely based on the use of serum prostate-specific antigen (PSA) and pathologic risk factors such as Gleason score and clinical stage. The use of serum PSA in clinical practice has resulted in significant stage migration and, as such, imaging modalities historically utilized to stage prostate cancer are no longer able to reliably identify the small amounts of prostate cancer most often found at presentation. Molecular imaging techniques have focused on improving sensitivity and specificity for cancer detection through knowledge of specific attributes of disease biology. The evolution of imaging techniques has created a new role for imaging in the management of prostate cancer.     

Using Biopsy to Detect Prostate Cancer

Transrectal ultrasound-guided systemic biopsy is the recommended method in most cases with suspicion of prostate cancer. Transrectal periprostatic injection with a local anesthetic may be offered as effective analgesia; periprostatic nerve block with 1% or 2% lidocaine is the recommended form of pain control. On initial biopsy, a minimum of 10 systemic, laterally directed cores is recommended, with more cores in larger glands. Extended prostate biopsy schemes, which require cores weighted more laterally at the base (lateral horn) and medially to the apex, show better cancer detection rates without increasing adverse events. Transition zone biopsies are not recommended in the first set of biopsies, owing to low detection rates. One set of repeat biopsies is warranted in cases with persistent indication. Saturation biopsy (≥20 cores) should be reserved for repeat biopsy in patients who have negative results on initial biopsy but who are still strongly suspected to have prostate cancer.Key words: Prostate cancer, Biopsy, Transrectal ultrasound, Prostate-specific antigen, Anesthesia, NomogramsProstate cancer rarely causes symptoms until it is advanced. Thus, suspicion of prostate cancer resulting in a recommendation for prostatic biopsy is most often raised by abnormalities found on digital rectal examination (DRE) or by serum prostate-specific antigen (PSA) elevations. Although there is controversy regarding the benefits of early diagnosis, it has been demonstrated that an early diagnosis of prostate cancer is best achieved using a combination of DRE and PSA.Transrectal ultrasound (TRUS)-guided, systematic needle biopsy is the most reliable method, at present, to ensure accurate sampling of prostatic tissue in men considered at high risk for harboring prostatic cancer on the basis of DRE and PSA findings. In very rare circumstances, a biopsy of a metastatic site (bone lesion) or a suspicious lymph node may be easier and more advantageous. There are also circumstances in which the usual transrectal route is not feasible (eg, status post-anteroposterior resection of the rectosigmoid; see Tissue Diagnosis in Patients with No Rectal Access section, below). As nearly universal as the approach, as nearly universal is the technique, namely a TRUS-guided biopsy using an 18-gauge needle to obtain a tissue core. To be certain, the same biopsy device and needle may be used to perform a finger-guided biopsy, but this is reserved for unusual circumstances (eg, TRUS imaging not available, finger-guided directed biopsy of suspicious nodule not seen on TRUS). Last, whereas in decades past physicians in many countries performed fine-needle aspiration of the prostate, today this technique is less and less often used, although advocates claim that it is cheaper, faster, easier to perform, and results in lower morbidity than any other technique developed to date. Appropriate training in performing transrectal fine-needle aspiration of the prostate and in interpreting the smears is, of course, essential.¹ Fine-needle aspiration plays a major role in the aforementioned situations in which diagnosis is established from nonprostatic tissue sources, such as lymph nodes and others.^2,3Since the landmark study by Hodge and colleagues⁴ demonstrating the superiority of TRUS guidance compared with digitally guided biopsy, the TRUS-guided biopsy technique has become the worldwide accepted standard in prostate cancer diagnosis. Statistical performance (sensitivity, specificity, positive and negative predictive values) of all other diagnostic tests (eg, DRE and PSA assay) is calculated according to the assignment (cancer present vs absent) made by prostate biopsy. Recognizing the fact that all sampling procedures, including prostate biopsies, incur the risk of returning false-negative results (ie, cancer is present but missed by the biopsies), calculation of the statistical performance characteristics of all other tests using biopsy outcomes as the gold standard are inherently incorrect and biased. Similarly, when comparing the statistical performance of various biopsy strategies, usually the most extensive strategy is chosen as the gold standard to define disease presence or absence, and the performance of all other strategies is calculated on the basis of that particular strategy, again incurring a significant bias due to the remaining falsenegative rate of even the most extensive sampling strategy.     

超声弹性成像技术在前列腺癌诊断中的应用

超声弹性成像技术是一项新兴的超声成像方法,可通过分析不同组织间机械组织差异区分组织软硬度,早期主要应用于乳腺、甲状腺结节的区分和定性。随着科技的进步和医疗水平的提高,目前弹性成像技术可在二维声像图的基础上,对感兴趣区域进行定性诊断和定量分析,已逐步应用于医学各领域相关研究和临床疾病的鉴别诊断。本文介绍了弹性成像的基本原理和目前弹性成像技术在医学领域中的相关应用,叙述了前列腺癌的发展趋势和目前常用的筛查、诊断方法,详细阐述了弹性成像技术在前列腺癌诊断中的应用方法和现状,分析总结了弹性成像技术在前列腺癌诊断中的应用价值。运用弹性成像技术无创、经济便捷、实时动态、可重复性好等优点,联合前列腺癌相关筛查、诊断检查,可有效帮助早期诊断前列腺癌,减少前列腺穿刺术的针数,提高前列腺癌的检出率。     

Recent Trends in Computer Assisted Diagnosis (CAD) System for Breast Cancer Diagnosis Using Histopathological Images

Breast cancer is one of the common type of cancer in females across the world. An early detection and diagnosis of breast cancer may reduce the mortality rate to a great extent. To diagnose breast cancer, different types of imaging modalities are used to collect samples like mammography, Computerized Tomography, Magnetic Resonance Imaging, Ultrasound and Biopsy. Histopathological images obtained from biopsy may influence how and at which stage the cancer is being diagnosed. The Computer Assisted Diagnosis (CAD) system helps the pathologists in early diagnosis of breast cancer. In this survey, the recently reported techniques for breast cancer diagnosis using histopathological images have been summarized. This study could be beneficial for: (i) Clinicians to receive second opinion from the CAD system for early diagnosis, and (ii) Researchers to analyze and enhance the existing state-of-art techniques used in CAD system, which may further reduce the gap of variability between intra and inter observer.     

Cancer de la prostate : la maladie localisée

Localized prostate cancer is characterized by a tumor confined to the prostate gland at clinical evaluation. Since the onset of PSA screening, the detection of localized prostate cancer has increased. Prognosis factors are clinical stadification, PSA value, PSA doubling time, tumor volume related to needle biopsy pathologic findings (Gleason score, percentage biopsies involved). Treatment depends on tumor prognosis, symptoms and performance status of the patient. Localized prostate cancer can be treated by surgery (radical prostatectomy, high intensity focused ultrasound) or radiotherapy (conformational radiation therapy, brachytherapy). Active follow-up can be proposed to very low risk patients.     

Prostate biopsy: current status and limitations

The technique of prostate biopsy has evolved over the past 10 years to improve our ability to detect prostate cancer. Extended biopsy schemes can be performed in the office under local anesthesia and are well tolerated. In addition to detection, the role of extended biopsy schemes in refining tumor grading and risk assessment has become better defined. This review discusses the evolution of prostate biopsy techniques from the sextant scheme to the extended scheme and demonstrates the latter's utility in clinical decision making.     

Identification and quantification of prosthetic mitral regurgitation by flow convergence method using transthoracic approach

Ultrasound is the preferred imaging modality in diagnosis of vascular complications following cardiac catheterization and intervention. In some cases, however, bleeding surrounding the femoral vessels, may severely distort the color Doppler images, making detection of venous complications especially difficult. This report refers to such a case where post-catheterization haematoma was suspected to cause an obstruction of the femoral vein. Spectral Doppler recordings of blood flow in the common femoral vein, up-stream, distal to the hemorrhagic area, confirmed the diagnosis of obstruction by demonstrating changes in the venous flow pattern in the common femoral vein, consistent with venous hypertension. Due to the poor quality of the ultrasound images, the exact cause of the obstruction had to be established by another imaging modality, not affected by haemorrhages. CT showed that the common femoral vein was compressed at the puncture site by surrounding haemorrhages. Thus, when bleeding due to cardiac catheterization is associated with possible venous obstruction and findings by color Doppler are equivocal due to degradation of the color-Doppler image, detection of venous hypertension by spectral Doppler, performed distal to the bleeding area, strongly supports the presence of venous obstruction where the exact cause may be established by CT.     

Ultrasound Elastography of the Prostate Using an Unconstrained Modulus Reconstruction Technique: A Pilot Clinical Study

A novel full-inversion-based technique for quantitative ultrasound elastography was investigated in a pilot clinical study on five patients for non-invasive detection and localization of prostate cancer and quantification of its extent. Conventional-frequency ultrasound images and radiofrequency (RF) data (~5 MHz) were collected during mechanical stimulation of the prostate using a transrectal ultrasound probe. Pre and post-compression RF data were used to construct the strain images. The Young's modulus (YM) images were subsequently reconstructed using the derived strain images and the stress distribution estimated iteratively using finite element (FE) analysis. Tumor regions determined based on the reconstructed YM images were compared to whole-mount histopathology images of radical prostatectomy specimens. Results indicated that tumors were significantly stiffer than the surrounding tissue, demonstrating a relative YM of 2.5 ± 0.8 compared to normal prostate tissue. The YM images had a good agreement with the histopathology images in terms of tumor location within the prostate. On average, 76% ± 28% of tumor regions detected based on the proposed method were inside respective tumor areas identified in the histopathology images. Results of a linear regression analysis demonstrated a good correlation between the disease extents estimated using the reconstructed YM images and those determined from whole-mount histopathology images (r² = 0.71). This pilot study demonstrates that the proposed method has a good potential for detection, localization and quantification of prostate cancer. The method can potentially be used for prostate needle biopsy guidance with the aim of decreasing the number of needle biopsies. The proposed technique utilizes conventional ultrasound imaging system only while no additional hardware attachment is required for mechanical stimulation or data acquisition. Therefore, the technique may be regarded as a non-invasive, low cost and potentially widely-available clinical tool for prostate cancer diagnosis.     

Repeat Targeted Prostate Biopsy under Guidance of Multiparametric MRI-Correlated Real-Time Contrast-Enhanced Ultrasound for Patients with Previous Negative Biopsy and Elevated Prostate-Specific Antigen: A Prospective Study

Objectives

To prospectively determine whether multi-parametric MRI (mpMRI) - contrast-enhanced ultrasound (CEUS) correlated, imaging-guided target biopsy (TB) method could improve the detection of prostate cancer in re-biopsy setting of patients with prior negative biopsy.

Methods

From 2012 to 2014, a total of 42 Korean men with a negative result from previous systematic biopsy (SB) and elevated prostate-specific antigen underwent 3T mpMRI and real-time CEUS guided TB. Target lesions were determined by fusion of mpMRI and CEUS. Subsequently, 12-core SB was performed by a different radiologist. We compared core-based cancer detection rates (CaDR) using the generalized linear mixed model (GLIMMIX) for each biopsy method.

Results

Core-based CaDR was higher in TB (17.92%, 38 of 212 cores) than in SB (6.15%, 31 of 504 cores) (p < 0.0001; GLIMMIX). In the cancer-positive TB cores, CaDR with suspicious lesions by mpMRI was higher than that by CEUS (86.8% vs. 60.5%, p= 0.02; paired t-test) and concordant rate between mpMRI and CEUS was significantly different with discordant rate (48% vs. 52%, p=0.04; McNemar’s test).

Conclusion

The mpMRI-CEUS correlated TB technique for the repeat prostate biopsy of patients with prior negative biopsy can improve CaDR based on the number of cores taken.     

Review of the literature: PCA3 for prostate cancer risk assessment and prognostication

Prostate cancer antigen 3 (PCA3) is a novel urine-based prostate cancer biomarker that has recently been studied extensively for the prediction of prostate biopsy results and treatment outcomes. Numerous studies have demonstrated that urinary PCA3 scores are predictive of prostate cancer detection on both initial and repeat biopsy. There is conflicting evidence on the relationship between PCA3 with aggressive tumor features and treatment outcomes. This article reviews the current evidence on PCA3 as a marker for prostate cancer detection and prognosis.     

Epidemiology of prostate cancer in the mediterranean population of Croatia--a thirty-three year retrospective study

Prostate cancer is a major public health problem of the male population in all the developed countries. This non-skin cancer is the foremost one facing man today. Prostate cancer has become the second leading cause of cancer death2. In this study we investigated changes in the prostate carcinoma incidence and manifestation during a thirty-three years period. The study included 1226 cases of prostate cancer diagnosed from 1972 to 2005 in the Primorsko-Goranska County, Croatia. The age-adjusted incidence of prostate cancer increased from 1.69 per 100,000 men annually in 1972 to 137.58 per 100,000 men annually in 2005, which is an 81.4-fold increase. The percentage ofpatients with bone metastases on the first medical examination decreased from 1972 (75%) to 2005 (15%). The most of the patients with bone metastases at the first medical examination were between 30 and 50 years old. Early detection measures, such as prostate specific antigen testing and transrectal ultrasound guided prostate biopsy combined with the raised public awareness of the disease, most probably resulted in an increase of incidence.     

Robotic Image-Guided Needle Interventions of the Prostate

Prostate biopsy and needle-directed prostate therapies are currently performed free-handed or with needle external templates under ultrasound guidance. Direct image-guided intervention robots are modern instruments that have the potential to substantially enhance these procedures. These may increase the accuracy and repeatability with which needles are placed in the gland. The authors’ group has developed a robot for precise prostate targeting that operates remotely alongside the patient in the magnetic resonance imaging scanner, as guided according to the image.Key words: Robot, Prostate, Direct image-guided intervention (DIGI), MRI compatible, Transrectal ultrasoundIt is estimated that the number of prostate biopsy procedures performed each year in the United States is on the order of 1 million. These yield the detection of approximately 230,000 new prostate cancers yearly.¹ The difference is explained not only by tests with true-negative results but also unfortunately by those in which the biopsies missed sampling the cancer. With the current stage migration,^1,2 tumors are becoming ever more difficult to sample; yet the staging of the disease becomes increasingly dependent on biopsy results. Moreover, wider treatment options are currently under evaluation for the management of localized prostate cancer, including needle-directed therapy methods such as cryotherapy,³ high-intensity focused ultrasound,⁴ and photodynamic therapy.^5,6The routine clinical modality for imaging the prostate is transrectal ultrasound (TRUS), for either diagnosis or needle therapy. Transrectal or transperineal needle access is performed either free-handed or with the use of a needle guide template. Systematic sampling protocols and gland-distributed treatment-planning algorithms have been developed to cope with the reduced accuracy of the ultrasound in cancer detection. The concept of focal therapy by the delivery of ablative therapy proximal to gland locations where positive biopsies were sampled is being tested,^7,8 but neither the biopsies nor therapies are yet directly targeting imaged tumor foci.New needle delivery mechanisms are therefore needed to increase the accuracy and repeatability with which needles can be placed in the gland. If accurate prostate cancer imaging were commonly used and accepted, such instruments could be immediately used for targeted biopsies or focal therapy. Today, prostate cancer image maps are still controversial, but accurate needle delivery mechanisms could be used to advance current procedures. For example, primary biopsies could better follow systematic plans, repeat biopsies could be tailored to target regions unsampled in previous biopsies, and expectant management biopsies could resample critical regions within the prostate. For treatment, these could potentially improve the execution and outcome of treatment plans and reduce side effects.Significant research is currently concentrated on the development of new prostate cancer markers and imaging methods. Their local validation could benefit from a precise biopsy mechanism. If correlated with pathology findings, cancer image maps could advance the field of targeted biopsies and focal therapies.The true potential of needle delivery mechanisms relies on their ability to operate with, be guided by, and use feedback from medical imaging equipment. Image guidance and navigation has been traditionally performed free-handed on preacquired images and with the use of spatial localizers, such as optical⁹ and magnetic trackers.¹⁰ The current trend, however, is for embedded systems that allow for re-imaging during the intervention for relocalization, treatment-planning updates, and quality control. We call these direct image-guided interventions (DIGI). The performance of DIGI is not new: the routine TRUS biopsy is performed under direct guidance. However, the new term is essential for distinguishing this important class of image-guided interventions from navigation based on preacquired imaging data.A DIGI needle delivery mechanism is best implemented by a computercontrolled device. This is a robot of special design and control architecture. DIGI robots are substantially different from the common surgeon-driven da Vinci® Surgical System (Intuitive Surgical, Sunnyvale, CA), and neither could take the other’s place. This article reviews clinical considerations and technical challenges for DIGI prostate robots and presents several such systems under development.