[Prostate cancer diagnosis using ultrasound elastography. Introduction of a novel technique and first clinical results]

Assessment of stricturing Crohn's disease: Current clinical practice and future avenues

Crohn’s disease (CD) is a chronic remittent idiopathic disease. Although the early phase of the disease is commonly characterized by inflammation-driven symptoms, such as diarrhea, the frequency of fibrostenotic complications in patients with CD increases over the long-term course of the disease. This review presents the current diagnostic options for assessing CD-associated strictures. In addition to the endoscopic evaluation of CD strictures, this review summarizes the currently available imaging modalities, including ultrasound and cross-sectional imaging techniques. In addition to stricture detection, differentiating between the primarily inflammatory strictures and the predominantly fibrotic ones is essential for selecting the appropriate treatment strategy (anti-inflammatory medical treatment vs endoscopical or surgical approaches). Therefore, recent imaging advances, such as contrast-enhanced ultrasound and ultrasound elastography, contribute to the development of non-invasive non-radiating imaging of CD-associated strictures. Finally, novel magnetic resonance imaging techniques, such as diffusion-weighted, motility and magnetization transfer imaging, as well as ¹⁸F-FDG PET/CT, molecular imaging approaches and biomarkers, are critically reviewed with regard to their potential role in assessing stricturing CD.

Endoscopic ultrasound: Elastographic lymph node evaluation

Different imaging techniques can bring different information which will contribute to the final diagnosis and further management of the patients. Even from the time of Hippocrates, palpation has been used in order to detect and characterize a body mass. The so-called virtual palpation has now become a reality due to elastography, which is a recently developed technique. Elastography has already been proving its added value as a complementary imaging method, helpful to better characterize and differentiate between benign and malignant masses. The current applications of elastography in lymph nodes (LNs) assessment by endoscopic ultrasonography will be further discussed in this paper, with a review of the literature and future perspectives.

Novel technique for MR elastography of the prostate using a modified standard endorectal coil as actuator

PURPOSE

To present a novel method for MR elastography (MRE) of the prostate at 3 Tesla using a modified endorectal imaging coil.

MATERIALS AND METHODS

A commercial endorectal coil was modified to dynamically generate mechanical stress (contraction and dilation) in a prostate phantom with embedded phantom "lesions" (6 mm diameter) and in a porcine model. Resulting tissue displacements were measured with a motion-sensitive EPI sequence at actuation frequencies of 50-200 Hz. Maps of shear modulus G were calculated from the measured phase-difference shear-wave patterns.

RESULTS

In the G maps of the phantom, "lesions" were easily discernible against the background. The average G values of regions of interest placed in the "lesion" (8.2 ± 1.9 kPa) were much higher than those in the background (3.6 ± 1.4 kPa) but systematically lower than values reported by the vendor (13.0 ± 1.0 and 6.7 ± 0.7 kPa, respectively). In the porcine model, shear waves could be generated and measured shear moduli were substantially different for muscle (7.1 ± 2.0 kPa), prostate (3.0 ± 1.4 kPa), and bulbourethral gland (5.6 ± 1.9 kPa).

CONCLUSION

An endorectal MRE concept is technically feasible. The presented technique will allow for simultaneous MRE and MRI acquisitions using a commercial base device with minor, MR-conditional modifications. The diagnostic value needs to be determined in further trials.

Efficacy of an artificial neural network-based approach to endoscopic ultrasound elastography in diagnosis of focal pancreatic masses

BACKGROUND & AIMS

By using strain assessment, real-time endoscopic ultrasound (EUS) elastography provides additional information about a lesion's characteristics in the pancreas. We assessed the accuracy of real-time EUS elastography in focal pancreatic lesions using computer-aided diagnosis by artificial neural network analysis.

METHODS

We performed a prospective, blinded, multicentric study at of 258 patients (774 recordings from EUS elastography) who were diagnosed with chronic pancreatitis (n = 47) or pancreatic adenocarcinoma (n = 211) from 13 tertiary academic medical centers in Europe (the European EUS Elastography Multicentric Study Group). We used postprocessing software analysis to compute individual frames of elastography movies recorded by retrieving hue histogram data from a dynamic sequence of EUS elastography into a numeric matrix. The data then were analyzed in an extended neural network analysis, to automatically differentiate benign from malignant patterns.

RESULTS

The neural computing approach had 91.14% training accuracy (95% confidence interval [CI], 89.87%-92.42%) and 84.27% testing accuracy (95% CI, 83.09%-85.44%). These results were obtained using the 10-fold cross-validation technique. The statistical analysis of the classification process showed a sensitivity of 87.59%, a specificity of 82.94%, a positive predictive value of 96.25%, and a negative predictive value of 57.22%. Moreover, the corresponding area under the receiver operating characteristic curve was 0.94 (95% CI, 0.91%-0.97%), which was significantly higher than the values obtained by simple mean hue histogram analysis, for which the area under the receiver operating characteristic was 0.85.

CONCLUSIONS

Use of the artificial intelligence methodology via artificial neural networks supports the medical decision process, providing fast and accurate diagnoses.

[Core needle biopsy twice negative with rising PSA level. Does imaging help?]

In compliance with guidelines in cases of suspected prostate cancer, the standard approach involves transrectal ultrasound-guided systematic biopsies. Currently, according to the new S3 guideline for prostate cancer, 10-12 tissue samples should be collected per patient and session. If these primary specimens are negative, the number of multiple biopsies is generally increased in the second session to improve the diagnostic certainty with more biopsies. At the latest when the second core needle biopsy is performed in the presence of rising prostate-specific antigen (PSA) level, an attempt is made to minimize the risk of overlooking prostate cancer by further increasing the number of multiple biopsies in the sense of achieving saturation. In this instance, the number ranges from 6 to 143 tissue samples per session. Studies have provided evidence that after two systematic random biopsies the same number of additional random biopsies does not accomplish any essential improvement of diagnostic certainty. There are hardly any studies in the literature dealing with the role of imaging procedures after negative prostate biopsies. In a prospective clinical trial including 132 patients with an average of 12 negative previous biopsies, a dramatically high number of prostate carcinomas (66 of 132) could be detected with innovative imaging (1-6 targeted biopsies). This raises the question of how reliably multiple systematic biopsies can in fact exclude the presence of cancer. Thus, particularly after a negative series of multiple biopsies, it appears to be expedient to use specific imaging to enhance diagnostic certainty through quality. However, prospective clinical validation of the diverse innovative methods seems to be important before broad application.

EUS elastography for the characterization of solid pancreatic masses

BACKGROUND

Differential diagnosis of solid pancreatic masses remains a challenge. EUS elastography, by analyzing tissue stiffness of the mass, may be of help in this setting.

OBJECTIVE

To evaluate the different elastographic patterns of solid pancreatic masses and the diagnostic accuracy of EUS elastography for malignancy.

DESIGN

Prospective, consecutive, descriptive study with a second blind evaluation of elastographic patterns for concordance analysis and use of a well-defined reference method for calculation of diagnostic accuracy.

PATIENTS

This study involved 130 consecutive patients with solid pancreatic masses and 20 controls with normal pancreases.

INTERVENTION

EUS elastography was performed by using a linear Pentax echoendoscope and Hitachi EUB-8500 US.

MAIN OUTCOME MEASUREMENTS

Elastographic patterns of solid pancreatic masses and accuracy of the technique for malignancy.

RESULTS

Mean (SD) size of the masses was 30.9 (12.5) mm. The final diagnosis was malignant tumor in 78 patients, inflammatory mass in 42 patients, and neuroendocrine tumor in 10 patients. Four elastographic patterns were described, with a high concordance among 2 blinded investigators. A green-predominant pattern, either homogeneous or heterogeneous, excluded malignancy with a high accuracy. On the contrary, a blue-predominant pattern, either homogeneous or heterogeneous, supported the diagnosis of malignant tumor. Sensitivity, specificity, positive and negative predictive values, and overall accuracy of EUS elastography for diagnosis of malignancy were 100%, 85.5%, 90.7%, 100%, and 94.0%, respectively.

LIMITATION

Single-center study.

CONCLUSION

EUS elastography is a useful tool for differential diagnosis of solid pancreatic masses. It provides specific patterns supporting the benign or malignant nature of the disease.

Endoscopic ultrasound elastography for evaluation of lymph nodes and pancreatic masses: a multicenter study

AIM

To evaluate the ability of endoscopic ultrasound (EUS) elastography to distinguish benign from malignant pancreatic masses and lymph nodes.

METHODS

A multicenter study was conducted and included 222 patients who underwent EUS examination with assessment of a pancreatic mass (n = 121) or lymph node (n = 101). The classification as benign or malignant, based on the real time elastography pattern, was compared with the classification based on the B-mode EUS images and with the final diagnosis obtained by EUS-guided fine needle aspiration (EUS-FNA) and/or by surgical pathology. An interobserver study was performed.

RESULTS

The sensitivity and specificity of EUS elastography to differentiate benign from malignant pancreatic lesions are 92.3% and 80.0%, respectively, compared to 92.3% and 68.9%, respectively, for the conventional B-mode images. The sensitivity and specificity of EUS elastography to differentiate benign from malignant lymph nodes was 91.8% and 82.5%, respectively, compared to 78.6% and 50.0%, respectively, for the B-mode images. The kappa coefficient was 0.785 for the pancreatic masses and 0.657 for the lymph nodes.

CONCLUSION

EUS elastography is superior compared to conventional B-mode imaging and appears to be able to distinguish benign from malignant pancreatic masses and lymph nodes with a high sensitivity, specificity and accuracy. It might be reserved as a second line examination to help characterise pancreatic masses after negative EUS-FNA and might increase the yield of EUS-FNA for lymph nodes.

Endoscopic ultrasound elastography for evaluation of lymph nodes and pancreatic masses: A multicenter study

AIM: To evaluate the ability of endoscopic ultrasound (EUS) elastography to distinguish benign from malignant pancreatic masses and lymph nodes.

METHODS: A multicenter study was conducted and included 222 patients who underwent EUS examination with assessment of a pancreatic mass (n = 121) or lymph node (n = 101). The classification as benign or malignant, based on the real time elastography pattern, was compared with the classification based on the B-mode EUS images and with the final diagnosis obtained by EUS-guided fine needle aspiration (EUS-FNA) and/or by surgical pathology. An interobserver study was performed.

RESULTS: The sensitivity and specificity of EUS elastography to differentiate benign from malignant pancreatic lesions are 92.3% and 80.0%, respectively, compared to 92.3% and 68.9%, respectively, for the conventional B-mode images. The sensitivity and specificity of EUS elastography to differentiate benign from malignant lymph nodes was 91.8% and 82.5%, respectively, compared to 78.6% and 50.0%, respectively, for the B-mode images. The kappa coefficient was 0.785 for the pancreatic masses and 0.657 for the lymph nodes.

CONCLUSION: EUS elastography is superior compared to conventional B-mode imaging and appears to be able to distinguish benign from malignant pancreatic masses and lymph nodes with a high sensitivity, specificity and accuracy. It might be reserved as a second line examination to help characterise pancreatic masses after negative EUS-FNA and might increase the yield of EUS-FNA for lymph nodes.

In vivo visualization of abdominal malignancies with acoustic radiation force elastography

The utility of acoustic radiation force impulse (ARFI) imaging for real-time visualization of abdominal malignancies was investigated. Nine patients presenting with suspicious masses in the liver (n = 7) or kidney (n = 2) underwent combined sonography/ARFI imaging. Images were acquired of a total of 12 tumors in the nine patients. In all cases, boundary definition in ARFI images was improved or equivalent to boundary definition in B-mode images. Displacement contrast in ARFI images was superior to echo contrast in B-mode images for each tumor. The mean contrast for suspected hepatocellular carcinomas (HCCs) in B-mode images was 2.9 dB (range: 1.5-4.2) versus 7.5 dB (range: 3.1-11.9) in ARFI images, with all HCCs appearing more compliant than regional cirrhotic liver parenchyma. The mean contrast for metastases in B-mode images was 3.1 dB (range: 1.2-5.2) versus 9.3 dB (range: 5.7-13.9) in ARFI images, with all masses appearing less compliant than regional non-cirrhotic liver parenchyma. ARFI image contrast (10.4 dB) was superior to B-mode contrast (0.9 dB) for a renal mass. To our knowledge, we present the first in vivo images of abdominal malignancies in humans acquired with the ARFI method or any other technique of imaging tissue elasticity.

Dynamic analysis of EUS used for the differentiation of benign and malignant lymph nodes

BACKGROUND

EUS elastography was reported to offer supplemental information that allows a better characterization of tissue, and that might enhance conventional EUS imaging.

OBJECTIVE

Our purpose was to apply real-time elastography during EUS examinations and to assess the accuracy of the differentiation of benign versus malignant lymph nodes.

DESIGN

Prospective cross-sectional feasibility study.

SETTING

Department of Surgical Gastroenterology, Gentofte University Hospital, Hellerup, Denmark.

PATIENTS

Patients diagnosed by EUS with cervical, mediastinal, or abdominal lymph nodes were included, with a total number of 78 lymph nodes examined. The final diagnosis of the type of lymph node was obtained by EUS-FNA cytologic analysis or by surgical pathologic examination and by a minimum 6 months of follow-up.

INTERVENTIONS

Hue histogram analysis of the average images computed from EUS elastography movies was used to assess the color information inside the region of interest and to consequently differentiate benign and malignant lymph nodes.

MAIN OUTCOME MEASUREMENTS

Differentiate between malignant and benign lymph nodes.

RESULTS

By using mean hue histogram values, the sensitivity, specificity, and accuracy for the differential diagnosis were 85.4%, 91.9%, and 88.5%, respectively, on the basis of a cutoff level of 166 (middle of green-blue rainbow scale). The proposed method might be useful to avoid color perception errors, moving artifacts, or possible selection bias induced by analysis of still images.

LIMITATIONS

Lack of the surgical standard in all cases.

CONCLUSIONS

Computer-enhanced dynamic analysis based on hue histograms of the EUS elastography movies represents a promising method that allows the differential diagnosis of benign and malignant lymph nodes, offering complementary information added to conventional EUS imaging.

Neue Techniken der Urosonographie

New sonographic techniques in urology, together with their principles of operation, will be presented. Together with the utilization of broadband ultrasound scanners and digital beam formers, leading to better spatial resolution and increased line density in ultrasound imaging, panorama sonography enables the outline of wide lateral regions independent of the width of the scanner. Spatial compound sonography achieves a comparatively better visualization of details in the b-mode image than has yet been available. The continuously improved 3-D, now leading to 4-D, techniques, which means real time capabilities, make the visualization of unrestricted imaging planes, which are not seen in conventional 2-D techniques, possible. The second harmonic imaging technique, including the special applications tissue harmonic imaging (THI) and contrast harmonic imaging (CHI), uses special ultrasound signal processing procedures for capturing and evaluating tissue hemoperfusion-here in combination with ultrasound contrast agents (UCA). Furthermore, microvascular imaging (MVI) enables the visualization of perfusion in tissues reaching the microcirculation regions. This leads to new possibilities for the assessment of pathological perfusion patterns, e.g. in andrology (perfusion of testicles) and uro-oncology (hyperperfusion of malignant regions).