Guidelines for Transrectal Ultrasonography-Guided Prostate Biopsy: Korean Society of Urogenital Radiology Consensus Statement for Patient Preparation, Standard Technique, and Biopsy-Related Pain Management

The Korean Society of Urogenital Radiology (KSUR) aimed to present a consensus statement for patient preparation, standard technique, and pain management in relation to transrectal ultrasound-guided prostate biopsy (TRUS-Bx) to reduce the variability in TRUS-Bx methodologies and suggest a nationwide guideline. The KSUR guideline development subcommittee constructed questionnaires assessing prebiopsy anticoagulation, the cleansing enema, antimicrobial prophylaxis, local anesthesia methods such as periprostatic neurovascular bundle block (PNB) or intrarectal lidocaine gel application (IRLA), opioid usage, and the number of biopsy cores and length and diameter of the biopsy needle. The survey was conducted using an Internet-based platform, and responses were solicited from the 90 members registered on the KSUR mailing list as of 2018. A comprehensive search of relevant literature from Medline database was conducted. The strength of each recommendation was graded on the basis of the level of evidence. Among the 90 registered members, 29 doctors (32.2%) responded to this online survey. Most KSUR members stopped anticoagulants (100%) and antiplatelets (76%) one week before the procedure. All respondents performed a cleansing enema before TRUS-Bx. Approximately 86% of respondents administered prophylactic antibiotics before TRUS-Bx. The most frequently used antibiotics were third-generation cephalosporins. PNB was the most widely used pain control method, followed by a combination of PNB plus IRLA. Opioids were rarely used (6.8%), and they were used only as an adjunctive pain management approach during TRUS-Bx. The KSUR members mainly chose the 12-core biopsy method (89.7%) and 18G 16-mm or 22-mm (96.5%) needles. The KSUR recommends the 12-core biopsy scheme with PNB with or without IRLA as the standard protocol for TRUS-Bx. Anticoagulants and antiplatelet agents should be discontinued at least 5 days prior to the procedure, and antibiotic prophylaxis is highly recommended to prevent infectious complications. Glycerin cleansing enemas and administration of opioid analogues before the procedure could be helpful in some situations. The choice of biopsy needle is dependent on the practitioners' situation and preferences.

Diagnostic Performance of MRI for Assessing Parametrial Invasion in Cervical Cancer: A Head-to-Head Comparison between Oblique and True Axial T2-Weighted Images

OBJECTIVE: To directly compare the diagnostic performance of true and oblique axial T2-weighted imaging (T2WI) for assessing parametrial invasion (PMI) in cervical cancer. MATERIALS AND METHODS: This retrospective study included 71 women with treatment-naive cervical cancer who underwent MRI that included both oblique and true axial T2WI, followed by radical hysterectomy. Two blinded radiologists (Radiologist 1 and Radiologist 2) independently assessed the presence of PMI on both sequences using a 5-point Likert scale. Receiver operating characteristic (ROC) curve analysis was performed, with a subgroup analysis for tumors sized > 2.5 cm and ≤ 2.5 cm in diameter. Inter-reader agreement was assessed with kappa (k) statistics. RESULTS: At hysterectomy, 15 patients (21.1%) had PMI. For Radiologist 1, the area under the ROC curve (AUC) was greater for oblique axial than for true axial T2WI {0.941 (95% confidence interval [CI] = 0.858–0.983) vs. 0.917 (95% CI = 0.827–0.969), p = 0.027}. The difference was not significant for Radiologist 2 (0.879 [95% CI = 0.779–0.944] vs. 0.827 [95% CI = 0.719–0.906], p = 0.153). For tumors > 2.5 cm, AUC was greater with oblique than with true axial T2WI (0.906 vs. 0.860, p = 0.046 for Radiologist 1 and 0.839 vs. 0.765, p = 0.086 for Radiologist 2). Agreement between the radiologists was almost perfect for oblique axial T2WI (k = 0.810) and was substantial for true axial T2WI (k = 0.704). CONCLUSION: Oblique axial T2WI potentially provides greater diagnostic performance than true axial T2WI for determining PMI, particularly for tumors > 2.5 cm. The inter-reader agreement was greater with oblique axial T2WI.

Adrenal Incidentaloma: Imaging Approach and Differential Diagnosis

Adrenal incidentaloma refers to adrenal masses that are accidentally found on imaging performed for other reasons, without clinical symptoms of adrenal disease. Generally, adrenal masses measuring less than 1 cm are not considered adrenal incidentalomas. The purpose of radiologic examination in evaluating non-functioning adrenal incidentalomas is to distinguish between benign and malignant masses to establish the treatment plan. In this review, based on previously published research and recommendations, we describe the radiologic approach for adrenal incidentaloma and describe the imaging findings of representative diseases.

Uterine Artery Embolization in Patients with Postpartum Hemorrhage: Clinical Efficacy and Safety of Treatment with N-Butyl-2-Cyanoacrylate

PURPOSE@#To evaluate the clinical efficacy and safety of uterine artery embolization (UAE) using N-butyl-2-cyanoacrylate (NBCA) in patients with postpartum hemorrhage (PPH).@*MATERIALS AND METHODS@#From February 2010 to May 2018, 14 patients (age: 28–39 years; mean: 33 years) underwent UAE using NBCA among 82 patients with PPH. Medical records were retrospectively reviewed to evaluate the patients characteristics, cause of PPH, embolization procedure, and outcomes.@*RESULTS@#Angiograms revealed extravasation (n = 10) or pseudoaneurysm (n = 4) in all patients. The causes of PPH were hysterotomy or hysterectomy related arterial injury (n = 11), cervical laceration (n = 2), and abnormal placentation (n = 1). UAE was performed with NBCA in all patients. Additional UAE with gelatin sponge particles was performed in two patients. Additional non-uterine artery embolization was performed in three patients. Coagulopathy was found in five (35.7%) patients. The technical and clinical success rates were 92.9% and 85.7%, respectively. One patient died from multi-organ failure eight days after UAE. One patient with abnormal placentation had pelvic organ ischemia due to multiple pelvic artery embolization.@*CONCLUSION@#UAE using NBCA is safe and effective for the patients with PPH showing extravasation or pseudoaneurysm.

Low-Tube-Voltage CT Urography Using Low-Concentration-Iodine Contrast Media and Iterative Reconstruction: A Multi-Institutional Randomized Controlled Trial for Comparison with Conventional CT Urography

OBJECTIVE: To compare the image quality of low-tube-voltage and low-iodine-concentration-contrast-medium (LVLC) computed tomography urography (CTU) with iterative reconstruction (IR) with that of conventional CTU. MATERIALS AND METHODS: This prospective, multi-institutional, randomized controlled trial was performed at 16 hospitals using CT scanners from various vendors. Patients were randomly assigned to the following groups: 1) the LVLC-CTU (80 kVp and 240 mgI/mL) with IR group and 2) the conventional CTU (120 kVp and 350 mgI/mL) with filtered-back projection group. The overall diagnostic acceptability, sharpness, and noise were assessed. Additionally, the mean attenuation, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM) in the urinary tract were evaluated. RESULTS: The study included 299 patients (LVLC-CTU group: 150 patients; conventional CTU group: 149 patients). The LVLC-CTU group had a significantly lower effective radiation dose (5.73 ± 4.04 vs. 8.43 ± 4.38 mSv) compared to the conventional CTU group. LVLC-CTU showed at least standard diagnostic acceptability (score ≥ 3), but it was non-inferior when compared to conventional CTU. The mean attenuation value, mean SNR, CNR, and FOM in all pre-defined segments of the urinary tract were significantly higher in the LVLC-CTU group than in the conventional CTU group. CONCLUSION: The diagnostic acceptability and quantitative image quality of LVLC-CTU with IR are not inferior to those of conventional CTU. Additionally, LVLC-CTU with IR is beneficial because both radiation exposure and total iodine load are reduced.

Ruptured Corpus Luteal Cyst: Prediction of Clinical Outcomes with CT

OBJECTIVE: To evaluate the determinant pretreatment CT findings that can predict surgical intervention for patients suffering from corpus luteal cyst rupture with hemoperitoneum. MATERIALS AND METHODS: From January 2009 to December 2014, a total of 106 female patients (mean age, 26.1 years; range, 17–44 years) who visited the emergency room of our institute for acute abdominal pain and were subsequently diagnosed with ruptured corpus luteal cyst with hemoperitoneum were included in the retrospective study. The analysis of CT findings included cyst size, cyst shape, sentinel clot sign, ring of fire sign, hemoperitoneum depth, active bleeding in portal phase and attenuation of hemoperitoneum. The comparison of CT findings between the surgery and conservative management groups was performed with the Mann-Whitney U test or chi-square test. Logistic regression analysis was used to determine significant CT findings in predicting surgical intervention for a ruptured cyst. RESULTS: Comparative analysis revealed that the presence of active bleeding and the hemoperitoneum depth were significantly different between the surgery and conservative management groups and were confirmed as significant CT findings for predicting surgery, with adjusted odds ratio (ORs) of 3.773 and 1.318, respectively (p 5.8 cm and concurrent active bleeding, the OR for surgery increased to 5.786. CONCLUSION: The presence of active bleeding and the hemoperitoneum depth on a pretreatment CT scan can be predictive warning signs of surgery for a patient with a ruptured corpus luteal cyst with hemoperitoneum.

Usefulness of resistive index on spectral Doppler ultrasonography in the detection of renal cell carcinoma in patients with end-stage renal disease

PURPOSE: The aim of this study was to explore the usefulness of the resistive index (RI) on spectral Doppler ultrasonography (US) in the detection of renal cell carcinoma (RCC) in patients with end-stage renal disease (ESRD). METHODS: Seventeen ESRD patients with kidneys in which renal masses were suspected in routine US were subjected. They underwent computed tomography scans and additional Doppler US for the characterization of the detected lesions. All underwent radical nephrectomy with the suspicion of RCC. Fourteen patients finally were included. RI measurements were conducted in the region of the suspected renal mass and the background renal parenchyma. The intraclass correlation coefficient was used to assess the reproducibility of the RI measurement. A paired t-test was used to compare the RI values between the renal mass and the background renal parenchyma (P<0.05). RESULTS: The RI values measured at the RCCs were significantly lower than those measured at the background renal parenchyma (0.41-0.65 vs. 0.75-0.89; P<0.001). The intrareader reproducibility proved to be excellent and good for the renal masses and the parenchyma, respectively (P<0.001). CONCLUSION: RI on spectral Doppler US is useful in detecting RCC in patients with ESRD. The RI values measured at the RCCs were significantly lower than those measured at the background renal parenchyma.

Role of Ultrasound Volume Measurements of Testes in Evaluation of Infertile Men with Azoospermia

PURPOSE: The purpose of our study was to assess the usefulness of ultrasounddetermined testicular volume in the evaluation of the infertile men with azoospermia. MATERIALS AND METHODS: A computerized search from October 2005 to June 2010 generated a list of 45 infertile men with azoospermia (mean age, 34 years; age range, 26-44 years) who underwent both scrotal ultrasound and testis biopsy. Ultrasounddetermined testicular volumes were compared between infertile men with obstructive azoospermia and those with non-obstructive azoospermia. RESULTS: Testicular volume for obstructive azoospermia ranged from 6.4 ml to 26.9 ml, with a median volume of 14.0 ml. This volume was significantly larger than that of those with non-obstructive azoospermia, which ranged from 1.0 ml to 12.8 ml, with a median volume of 6.1 ml (p < 0.001). The area under the ROC curve for distinguishing non-obstructive azoospermia from obstructive azoospermia using testicular volume was 0.91. A cutoff value of less than or equal to 11.4 ml could distinguish non-obstructive azoospermia from obstructive azoospermia, with a sensitivity of 94.1% (95% CI; 71.3-99.9%) and a specificity of 73.3% (95% CI; 54.1-87.7%). CONCLUSION: Ultrasound-determined testicular volume can be helpful in the differentiation of obstructive azoospermia from non-obstructive azoospermia.

Role of Ultrasound in Male Infertility

US evaluation is the mainstay of diagnostic imaging of infertile men. In this editorial, we review the spectrum of diseases responsible for male infertility, discuss the way in which US imaging studies can be used for evaluation of male infertility, and illustrate characteristic US imaging features that allow for specific diagnosis. The discussion will be divided into three main categories: obstruction in sperm passage, impairment of sperm function, and defect in sperm genesis.

In Vivo MR Imaging of Magnetically Labeled Mesenchymal Stem Cells in a Rat Model of Renal Ischemia

OBJECTIVE: This study was designed to evaluate in vivo MR imaging for the depiction of intraarterially injected superparamagnetic iron oxide (SPIO)-labeled mesenchymal stem cells (MSCs) in an experimental rat model of renal ischemia. MATERIALS AND METHODS: Left renal ischemia was induced in 12 male Sprague-Dawley rats by use of the catheter lodging method. In vivo MR signal intensity variations depicted on T2*-weighted sequences were evaluated in both the left and right kidneys prior to injection (n = 2), two hours (n = 4), 15 hours (n = 2), 30 hours (n = 2) and 72 hours (n = 2) after injection of SPIO-labeled MSCs in both kidneys. Signal intensity variations were correlated with the number of Prussian blue stain-positive cells as visualized in histological specimens. RESULTS: In an in vivo study, it was determined that there was a significant difference in signal intensity variation for both the left and right cortex (40.8 +/- 4.12 and 26.4 +/- 7.92, respectively) and for both the left and right medulla (23.2 +/- 3.32 and 15.2 +/- 3.31, respectively) until two hours after injection (p < 0.05). In addition, signal intensity variation in the left renal cortex was well correlated with the number of Prussian blue stain-positive cells per high power field (r = 0.98, p < 0.05). CONCLUSION: Intraarterial injected SPIO-labeled MSCs in an experimental rat model of renal ischemia can be detected with the use of in vivo MR imaging immediately after injection.

Quality Assessment of Ultrasonographic Equipment Using an ATS-539 Multipurpose Phantom

PURPOSE: To determine the rate of congruence and to standardize assessment of US (ultrasound) phantom images with the use of an ATS-539 multipurpose phantom for US equipment currently utilized in Korea MATERIALS AND METHODS: US phantom images were scanned with a 3.0-5.0 MHz convex transducer and were digitized by use of an analogue-digital converter. Members of a committee with consent evaluated the US phantom images from 108 types of ultrasound equipment. The dead zone, vertical and horizontal measurement, axial/lateral resolution, focal zone, sensitivity, functional resolution and gray scale/dynamic range were evaluated. Congruence or incongruence of ultrasound equipment was determined based on the results of dead zone, axial/lateral resolution and gray scale/dynamic range measurements. Other factors were evaluated for the possibility as criteria with the use of the Mann-Whitney U test and receiver operator characteristic (ROC) curve analysis. RESULTS: The dead zone, axial/lateral resolution and gray scale/dynamic range were 91.7%, 94.4% and 76.9%, respectively, for suitable US equipment. Considering all three factors, 78 types of ultrasound equipment were passed. The congruence rate of focal zone and functional resolution were 62.4% and 69.3% of the US equipment, respectively. CONCLUSION: Of the US equipment, 72.2% of the equipment was acceptable based on the dead zone, axial/lateral resolution, and gray scale/dynamic range measurements as determined with the use of an ATS-539 phantom. Focal zone and 8 mm-functional resolution can be useful as a standard in the assessment of a US phantom image.

CT and MR Imaging of the Buccal Space: Normal Anatomy and Abnormalities

The buccal space is an anatomical compartment lying anterior to the masticator space and lateral to the buccinator muscle. Since the major purpose of imaging is to define the likely anatomic origin and also the extent of a given lesion, thorough knowledge of the normal anatomy of the buccal space is essential, and this knowledge can aid the physician in narrowing down the list of possible maladies on the differential diagnosis. We illustrate here in this paper the important anatomic landmarks and typical pathologic conditions of the buccal space such as the developmental lesions and the neoplastic lesions. Knowledge of the expected pathologic conditions is useful for the radiologist when interpreting facial CT and MR images.

Imaging Features of Gray-Scale and Contrast-Enhanced Color Doppler US for the Differentiation of Transient Renal Arterial Ischemia and Arterial Infarction

OBJECTIVE: To characterize the imaging features on gray-scale and contrast-enhanced color Doppler US images which differentiate renal ischemia from renal infarction. MATERIALS AND METHODS: The segmental renal arteries of eight healthy rabbits were surgically ligated. In four of these rabbits, the ligated renal artery was released 60 minutes after arterial occlusion to cause transient ischemia. In the remaining four rabbits, the arterial ligation was retained to cause a permanent infarction. The gray-scale and contrast-enhanced color Doppler US imaging features of the involved renal parenchyma of both ischemia and infarction groups were compared with respect to the presence or absence of parenchymal swelling, echogenicity changes, tissue loss and perfusion defects. RESULTS: Parenchyma swelling, echogenic changes, tissue loss and perfusion defects were found to be more extensive in the infarction than the ischemia group. The hyperechoic areas reperfused with blood flow recovered normal echogenicity and perfusion, whereas the hyperechoic areas without reperfusion became renal infarcts. CONCLUSION: Gray-scale and contrast-enhanced color Doppler US showed that the hyperechoic areas with reperfusion may reverse to normal parenchyma and allow the differentiation of renal ischemia from renal infarction.

Buccal Space Lesions: A New Classification Based on CT and MR Imaging Findings

PURPOSE: To present a new classification based on the CT and MR imaging findings of buccal space lesions, and to propose guidelines for their radiologic differentiation. MATERIALS AND METHODS: Sixty-two histopathologically confirmed or clinically diagnosed buccal space lesions were classified on the basis of their morphologic appearance and extension to adjacent space as either (1) a mass with a distinct margin, confined to the buccal space; (2) a mass with surrounding infiltration, confined to the buccal space; or (3) a multi-space occupying mass. RESULTS: Type 1 included pleomorphic adenoma, ex-pleomorphic adenoma, carcinoma, B-cell lymphoma, acinic cell carcinoma, rhabdomyosarcoma, glomus tumor and ameloblastoma, and differentiation between malignant and benign neoplasms was not possible. Type 2 included adenoid cystic carcinoma, abscess, complicated dermoid cyst, and Kimura disease. T-cell lymphoma, neurofibroma, vascular malformation, inflammation, and foreign body granuloma pertained to type 3, and each type-3 entity showed different imaging characteristics. CONCLUSION: This new classification based on CT and MR imaging characteristics may provide useful guidelines for predicting the differential diagnosis of buccal space lesions.

Imaging Findings of Retroperitoneal Ganglioneuroma

PURPOSE: To characterize the typical radiologic appearance of ganglioneuromas of the adrenal gland and extra-adrenal retroperitoneum. MATERIALS AND METHODS: The findings of diagnostic imaging studies (CT, n=5; ultrasound, n=1) involving six patients aged 19-58 years with pathologically proven ganglioneuroma were retrospectively analyzed by three radiologist in terms of the lesions' size, shape, margin, location, CT attenuation (unenhanced/contrast-enhanced), necrosis, calcification, relationship with adjacent vessels, and US echogenicity. RESULTS: The maximum diameter of the six tumors ranged from 10 to 14 (mean, 11.3) cm, and the margin was well-defined in all cases. The homogeneous or slightly heterogeneous attenuation demonstrated at unenhanced CT was less than that of muscle. Dense nodular calcification was present in one case. At contrast-enhanced CT, enhancement was poor (n=5), mild and septum-like, or delayed, heterogeneous and focal (n=3), or involved subtle foci (n=1). In no case was there evidence of necrosis or hemorrhage. Local invasion was absent, but adjacent vascular encasement (n=2) or displacement (n=2) occurred. Ultrasonic examination demonstrated low echogenicity and mild heterogeneity (n=1). CONCLUSION: A ganglioneuroma is an uncommon benign neural crest tumor which should be included in the differential diagnosis of a retroperitoneal mass which presents as a well-defined tumor, tend to encase or displace adjacent major blood vessels, and shows low attenuation at unenhanced CT and poor or septum-like focal enhancement at contrast-enhanced CT.

Ruptured Corpus Luteal Cyst: CT Findings

OBJECTIVE: To evaluate the CT findings of ruptured corpus luteal cysts. MATERIALS AND METHODS: Six patients with a surgically proven ruptured corpus luteal cyst were included in this series. The prospective CT findings were retrospectively analyzed in terms of the size and shape of the cyst, the thickness and enhancement pattern of its wall, the attenuation of its contents, and peritoneal fluid. RESULTS: The mean diameter of the cysts was 2.8 (range, 1.5-4.8) cm; three were round and three were oval. The mean thickness of the cyst wall was 4.7 (range, 1-10) mm; in all six cases it showed strong enhancement, and in three was discontinuous. In five of six cases, the cystic contents showed high attenuation. Peritoneal fluid was present in all cases, and its attenuation was higher, especially around the uterus and adnexa, than that of urine present in the bladder. CONCLUSION: In a woman in whom CT reveals the presence of an ovarian cyst with an enhancing rim and highly attenuated contents, as well as highly attenuated peritoneal fluid, a ruptured corpus luteal cyst should be suspected. Other possible evidence of this is focal interruption of the cyst wall and the presence of peritoneal fluid around the adnexa.

Foreign Body Granuloma and Breast Cancer in the Augmented Breast: Mammography, US, MRI, and FDG-PET

The mammographic or physical evaluation of breast parenchymal abnormalities in the presence of radiopaque implants or silicone injections is difficult; mammography often fails to discriminate between breast cancer and a radiopaque dense breast. Although the sonographic evaluation of a palpable mass in an augmented breast may be impaired by the presence of posterior acoustic shadowing, the modality may be helpful in evaluating such masses, and dynamic contrast-enhanced MR imaging facilitates differentiation. FDG-PET is a possible alternative diagnostic tool for the evaluation of parenchymal lesions under these circumstances, but its drawbacks are its high cost and limited availability. The sensitivity and specificity of both FDG-PET and MRI can be improved by correlating their findings with those of radiological studies, and through an awareness of potential false-negative and false-positive causes.

Nonvascular Interventions of the Urinary Tract

Nonvascular intervention of the urinary tract is a well-established uroradiologic subspecialty, which is more important for avoiding invasive open surgery in the age of rising demand about the value of less invasive treatment. Various kinds of nonvascular intervention are recently performed under image-guidance and are as follows: percutaneous nephrostomy, percutaneous nephrostolithotomy, percutaneous dilatation of the urinary tract, sclerotherapy for renal cysts, percutaneous catheter drainage, percutaneous foreign body retrieval and biopsy. Percutaneous nephrostomy is a basic technique to provide a direct access to urinary tract, which makes it possible to perform other interventional procedures. Although nonvascular intervention may produce some complications, it is generally considered to be less invasive than open surgery and has advantages such as short hospital stay, early return to normal life and therefore economic savings. This review is described to help clinicians easily understand the procedures, indications, techniques, and complications with figures of cases the authors experienced.

Efficacy of Spiral CT in the Evaluation of Peritoneal Seeding of Gastric Cancer

PURPOSE: To determine usefulness of spiral CT in the preoperative evaluation of peritoneal seeding from a gastric carcinoma. MATERIALS AND METHODS: From a database of 411 consecutive patients with surgically proven advanced gastric cancinoma obtained over a six-month period, 17 with peritoneal seeding and a control group of 24 without peritoneal seeding underwent spiral CT scanning with 7 -8 mm scan thickness and interval during the portal phase. Preoperative CT images were analyzed by two readers who reached a consensus with regard to the presence and location of the ascites, thickening of the parietal peritoneum, and changes in the omentum and mesentery. RESULTS: Ascites was present in 47% (8/17) of patients with peritoneal seeding The right subhepatic space (n=6, 35%) and right paracolic gutter (n=5, 29%) but not the cul-de-sac (n=2, 12%)-were common sites of fluid collection. Permeative changes in the omentum and mesentery were seen in 18% (3/17) and 12% (2/17) of patients, respectively. Among five controls with false positive results, ascites in the cul-de-sac was present in three (two males and one female, 12%) while omental nodules and a thickened peritoneum were found in two (8%) and one (4%), respectively. In nine controls with false negative results, small disseminated nodules were seen in the mesentery and omentum at surgical field. The sensitivity and specificity of spiral CT were 47% (8/17) and 79% (19/24), respectively. CONCLUSION: In terms of sensitivity and specificity, spiral CT is not especially accurate in distinguishing peritoneal seeding from gastric carcinoma.

The Usefullness of the Transrectal Ultrasonography in the Diagnosis of the Prostate Cancer: Comparison with Systemic Sextant Biopsy

PURPOSE: To retrospectively compared the usefulness of the transrectal ultrasonography LEAVE A SPACE(TRUS) and systemic sextant biopsy in the diagnosis of prostate cancer. MATERIALS AND METHODS: A total of 84 patients with clinical and laboratory findings suggestive of prostate cancer underwent TRUS and systemic sextant biopsy. Nine patients with diffuse prostatic lesion had been excluded from the list. Following sonographic evaluation, additional targeted biopsy for the focal lesion was performed in 14 patients. A total of 464 biopsy specimens were obtained and retrospectively compared with the sonographic findings. RESULTS: For cancer, the sensitivity, specificity and false-positive rate of TRUS were 48%, 97% and 53%, respectively. The hypoechoic nodules seen in prostate cancer were more commonly located in the outer half of the peripheral zone of the prostate, while most BPH lesions were located in the inner half of this zone. Between prostate cancer and BPH there was a statistically significant difference in the location of hypoechoic nodules revealed by TRUS (p=0.01). CONCLUSION: The location of the hypoechoic nodules provides useful information for differentiating between BPH nodoles and malignant prostatic nodules and may reduce the false-positive rate of TRUS in the diagnosis of prostate cancer.