Prostate Biopsy Strategy Modeling by Clinical Data

Transcription

1 Prostate Biopsy Strategy Modeling by Clinical Data Jinjiang Liu, Jingjing Liang, Yihua Lan* School of Computer and Information Technology, Nanyang Normal University, Nanyang , China *Corresponding author ( Abstract Prostate biopsy is considered as the gold standard in the diagnosis of prostate cancer. Through a biopsy, the doctors can not only evaluate the malignant degree, but also know the clinical stage of the cancer. A traditional strategy is carried out to get the mass distribution by taking slices with a number of prostate entities and manual calibrating the cancer position to get the 3-d reconstruction. However, the entity biopsy slicing costs highly, and does not represent all the cancer distribution for each group of people. Considering the biopsy data collecting is relatively easy and cheap to hospital, we hope to obtain a more optimized biopsy strategy by a lot of statistics. Therefore, this paper proposed a kind of method to get the mass center position distribution of prostate and formulate the prostate biopsy strategy by learning the statistics results of clinical data. Comparing with the slicing method, Prostate biopsy strategy modeling method by clinical data is easier with lower cost. After modeling, the proposed prostate biopsy strategy is fairly accurate. the information only comes from 12 biopsy positions, so a tiny discrepancy between the distribution estimation and actual distribution still exists. The experimental results show that taking the existing biopsy results as data can indeed improve prostate biopsy solution to a certain extent. Due to the higher accessibility to the clinical prostate biopsy data, we could achieve the optimal biopsy strategy when getting the clinical big data. Key words: Transrectal Ultrasonography, Prostate Cancer, Prostate Biopsy, Three Dimensional Reconstructions, Biopsy Strategy 1. INTRODUCTION As the influence of the factors such as the population ages, diet, health and environment, there is an upward trend in the incidence of prostate cancer (Hong et al., 2014). It has now become the first male urinary and reproductive system malignant tumor. In Europe, prostate cancer accounts for 13% of the total number of male cancers, and 10% of all cancer deaths in men (Loeb et al., 2013). The incidence of prostate cancer is lower than the former in Asia, but over the past 10 years it has shown a trend of rising year by year. Prostate cancer is always not typical and more and more prostate cancer hyperplasia with symbiosis (Bjurlin et al.,2014;xu et al., 2013). However, the exact diagnosis is always late when the prostate cancer occurs, which results in missing the best timing of the radical surgery and other effective treatments. With the improvement of medical security level, timely and early to make a man of suspected prostate cancer for ultrasound guided by transrectal ultrasonography prostate biopsy, early diagnosis and treatment for prostate cancer is of great significance (Lee et al., 2014). Prostate biopsy is considered as the gold standard in the diagnosis of prostate cancer (Anastasiadis etal.,2013). Through a biopsy, the doctors can not only evaluate the malignant degree of tumor, but also know the clinical stage, which could be provided as the basis for further treatment choice. However, at present the piercing indications, positioning, pin number, biopsy path and anesthesia scheme still have many problems and controversies. The transrectal ultrasonography guided system of more than ten-needle biopsy in the diagnosis of prostate cancer has replaced the original six-needle biopsy (Fiset et al., 2013). In order to improve the detection rate of prostate cancer since more clinical manifestations of prostate cancer are not obvious, recently the method of saturation of prostate biopsy has been put forward. Since then, despite the lack of widespread argument the saturated biopsy method basically has been adopted at least 20-needle puncture. Studies show that this way of puncture has certain defects. For saturated biopsy in patients with suspected prostate cancer, its aim is to improve the detection rate of prostate cancer. There are two critical aspects to achieve this goal, the part of the total number of needle puncture and biopsy. Recent research suggests that even if the biopsy puncture needle 24 for the first time, there are still 30% of the patients diagnosed again to perform a biopsy for prostate cancer. After the analysis, we have found the reasons as follows. First of all, the volume of the prostate is the important factor influencing the detection rate of prostate cancer. With multiple needle biopsy, in patients with prostate volume larger it s cannot reach saturation level of biopsy, whereas in patients with prostate volume smaller it s always drop as the super saturation level. Furthermore, the high incidence of prostate cancer is distributed in the 33

2 prostate peripheral zone, while the hyperplasia of prostate is on the transitional zone. The increases transitional belt extrudes the peripheral zone, which lead to biopsy samples weeks with ingredients to reduce both at home and abroad, so the results may affect the detection rate of tumor. In addition, prostate cancer is always distributed in front and on both sides of the tip of the prostate. Most doctors take through the perineum or a way to enter the biopsy of the rectum. The study found that, at the same time using two kinds of biopsy approaches, and transforming the angle of the needle, we can gain more regions and tissue to improve detection rate of the tumor (Ismail et al., 2013). After considering all the factors above, we need the data for three dimensional reconstructions as well as the computer guided assistance so as to improve the accuracy of puncture. We need to value the saturated biopsy for prostate cancer when the clinical symptoms of the patients are not very obvious. Doctors should improve the detection rate of prostate cancer while considering how to select the most appropriate treatment to avoid excessive treatment. We need comprehensively consider the size, shape, the gland of prostate anatomy area to make the biopsy achieve its desired effect, no matter saturated or not. The following part will be detailed mathematical modeling and analysis of the problem. 2. MODELING BY CLINICAL DATA Prostate biopsy is the primary mean of clinical diagnosis of prostate cancer. The traditional prostate biopsy uses the method by transrectal ultrasonography guided surgery for suspicious prostatic nodules. By transrectal ultrasonography guided systematic biopsy of the prostate (TRUS) 6 by Hodge first proposed in 1989, has now been accepted by most scholars, which become the standard operation for system of prostate biopsy. The six parts include the left and right part of prostate around the bottom of the leaves, middle, and tip. With the 6-point conventional puncture is generally accepted, people began to increase the quantity of the puncture point, puncture at 8-point biopsy (based on six point method combining with two points on the peripheral part), 10- point biopsy (based on 6-point method adding the two points on the transition zone of each leaf), 11-point biopsy (based on 6-point method increasing the points on the side and the transition zone of each side as well as the center line), 12-point biopsy (based on 10-point method adding points on each leaf peripheral zone profile), 13-point biopsy (based on 10-point method adding points in the middle zone profile) etc. Begin Prostate biopsy results Formulate the distribution model Formulate the prostate size knowage Clinical case The optimal biopsy strategy Doctor knowage Simulation and assessment End? No Yes End Figure 1. Prostate biopsy strategy flow chart modeling by clinical data With the increase of the number of puncture points, the biopsy positive detection rate has been greatly improved. However, it brings about more pain and complications to the patients. In addition, in order to further increase the rate of detection, doctors often need to measure positive patients with secondary puncture. This is not only a great pain to the patient, but also related to a lot of symptoms such as blood urine, blood stools and blood fine. It will make it worse and even cause infections. Zeng et al believe 10-point puncture is a more appropriate choice through the experiments of statistical different puncture point number detection rate and complications (Zeng et al., 2001). Furthermore, prostate biopsy puncture detection rate is related to prostate volume. Generally, the larger the prostate is, the smaller the detected probability is. Recently, research has 34

3 shown that for prostate biopsy, traditional 6-point method has a great discrepancy in the statistical model. Zeng et al take slices with a large number of entities of prostate biopsy, and let doctors manual calibrate cancer position to get the 3-d reconstruction (Zeng et al., 2001). They calculate the 6, 8, 10 point of optimal puncture point selection scheme according to the nonlinear optimization algorithm based on 280 samples of prostate. And they use 3-d visual puncture the piercing process system simulation, the result is satisfactory. However, the entity biopsy slicing cost is very high, and do not represent all the cancer distribution for each group of people. There are great differences in size and distribution of tumors between Europeans and Asians. For different ages, different sizes of the prostate of patients, the distribution of cancer may also be different. Considering the biopsy data collecting is relatively easy and cheap to hospital, we hope to obtain a more optimized biopsy strategy by a lot of statistics. Therefore, we proposed the following strategy. For verifying getting the cancer mass distribution center position and size by puncture results information is really meaningful, we take a lot of simulated experiments. Results showed the mass position and size information do have some confidence in the result, but unable to get the overall sense of the complete distribution. However, some confidence results could also guide the forthcoming prostate biopsy. 3. EXPERIMENTS AND RESULTS In the simulation, we first set the position distribution of mass centers of cancer, where the simulation "patient" individual cancer mass center position is set according to the probability distribution of random generation. Then we set the cancer mass size distribution, where the simulation "patient" individual cancer mass size is set according to the probability of uniform distribution generation. After that, we simulate the puncture process, where it is taken under the three dimensional guidance, and there are some errors, but it is roughly the three-dimensional normal distribution. We assume that the size of the prostate is cubic centimeter (about a chestnut size), and the volume size of each biopsy tissue is approximately cubic millimeter, about 1/6000 of the prostate. Then based on the simulation results, we get the distribution model of the prostate after mathematical modeling. Figure 2 shows the test results on the basis of 2000 cases. (a) (b) (c) (d) Figure 2. The number for getting tumor tissue or not for different tumor size((a) is 1/94, (b) is 1/48, (c) is 1/28, (d) is 1/18) 35

4 When the size of cancerous tumor is 1/750 of that of the prostate, the number of negative cases is 1777, while the number of positive cases is 223, among them, 217 cases for 1 needle, and 217 cases for 2 needles. When the size of cancerous tumor is 1/220 of that of the prostate, the number of negative cases is 1523, while, the number of positive cases is 477, among them, 422 cases for 1 needle, 54 cases for 2 needles, and 3 cases for 3 needles. When the size of cancerous tumor is 1/94 of that of the prostate,the number of negative cases is 1147, while the number of positive cases is 853, among them, 584 cases for 1 needle, 214 cases for 2 needles, 50 cases for 3 needles, 4 cases for 4 needles, and 1 cases for 5 needles. When the size of cancerous tumor is 1/48 of that of the prostate, the number of negative cases is 882, while the number of positive cases is 1118, among them, 571 cases for 1 needle, 309 cases for 2 needles, 108 cases for 3 needles, 55 cases for 4 needles, 2 cases for 5 needles, and 1 cases for 6 needles. When the size of cancerous tumor is 1/28 of that of the prostate,the number of negative cases is 703, while the number of positive cases is 1297, among them, 491 cases for 1 needle, 307 cases for 2 needles, 254 cases for 3 needles, 170 cases for 4 needles, 61 cases for 5 needles, 12 cases for 6 needles, and 2 cases for 7 needles. When the size of cancerous tumor is 1/18 of that of the prostate, the number of negative cases is 549, while the number of positive cases is 1451, among them, 410 cases for 1 needle, 308 cases for 2 needles, 258 cases for 3 needles, 204 cases for 4 needles, 151 cases for 5 needles, 81 cases for 6 needles, 31 cases for 7 needles, and 8 cases for 8 needles. Table 1.Simulation patient mass distribution center location (4 3 4) Table 2.Position distribution of mass centers only by addition (4 3 4)

5 Table 3. Position distribution of mass centers by modeling (4 3 4) Table point prostate biopsy strategy getting by the mass distribution (4 3 4) (X represents puncture, O represents not) O X X O X O O X O X X O X O O X O X X O X O O X In the case of a mass with large volume, the possibility becomes larger by taking the 12-point biopsy strategy. Of course, the possibility of the successful biopsy is related to the density of mass distribution as well as the biopsy strategy. The density of mass distribution in the simulation is shown in Table 1 and Figure 3, and a 12-point prostate biopsy strategy getting by the mass distribution is shown in Table 4. 37

6 Figure 3.The simulation patient mass center position distribution After modeling, the distribution of mass centers (Table 3) is really better than the distribution only by addition (table 2).Since the information only comes from 12 biopsy positions, the distribution estimation and actual distribution are still different a bit. The experimental results show that taking the existing domestic biopsy results as data, we can indeed improve the efficiency of the prostate biopsy solution to a certain extent, but the optimal results are hard to achieve because of the lack of data. 4. CONCLUSIONS Comparing with taking slices with a large number of entities of prostate biopsy and manual calibrating the cancer position to get the 3-d reconstruction, this paper proposed a new method to get the position distribution of mass centers of prostate by learning the statistics result of the clinical biopsy results. The latter one is proved to be relatively easier with a lower cost. Although the proposed method improves prostate biopsy accuracy, its potential will be fulfilled by the aid of big data. Acknowledgements This work was financially supported in part by the National Natural Science Foundation of China (Grant No , U ), China Postdoctoral Science Foundation(Grant No. 2015M572142), the key scientific and technological project of HeNan ( ), the Research Foundation for Advanced Talents of Nanyang Normal University (ZX ). REFERENCES Anastasiadis, A., Zapala, L., Cordeiro, E., Antoniewicz, A., Dimitriadis, G., and De Reijke, T. (2013)"Complications of prostate biopsy", Expert Review of Anticancer Therapy, 13(7),pp Bjurlin, M.A., Meng, X., Le Nobin, J., Wysock, J.S., Lepor, H., Rosenkrantz, A.B., and Taneja, S.S. (2014) "Optimization of prostate biopsy: the role of magnetic resonance imaging targeted biopsy in detection, localization and risk assessment",the Journal of urology, 192(3), pp Fiset, P.O., Aprikian, A., and Brimo, F. (2013), "Length of prostate biopsy cores: does it impact cancer detection?",the Canadian journal of urology, 20(4),pp Hong, C.W., Amalou, H., Xu, S., Turkbey, B., Yan, P., Kruecker, J., Pinto, P.A., Choyke, P.L., and Wood, B.J. (2014)"Prostate biopsy for the interventional radiologist",journal of Vascular and Interventional Radiology, 25(5), pp Ismail, M.T., and Gomella, L.G. (2013) "Transrectal prostate biopsy", Urologic Clinics of North America,40(4),pp Lee, C., and Woo, H.H. (2014)"Current methods of analgesia for transrectal ultrasonography (TRUS) guided prostate biopsy a systematic review", BJU international, 113(Supplement S2), pp Loeb, S., Vellekoop, A., Ahmed, H.U., Catto, J., Emberton, M., Nam, R., Rosario, D.J., Scattoni, V., and Lotan, Y. (2013), "Systematic review of complications of prostate biopsy", European urology, 64(6), pp Xu, H., Lasso, A., Guion, P., Krieger, A., Kaushal, A., Singh, A.K., Pinto, P.A., Coleman, J., Grubb III, R.L., and Lattouf, J.-B. (2013) "Accuracy analysis in MRI-guided robotic prostate biopsy", International journal of computer assisted radiology and surgery, 8(6),pp Zeng, J., Bauer, J., Zhang, W., Sesterhenn, I., Connelly, R., Lynch, J., Moul, J., and Mun, S.K. (2001), "Prostate biopsy protocols: 3D visualization based evaluation and clinical correlation",computer Aided Surgery, 6(1),pp