Prospective, randomized comparison of mechanical and electronic radial endoscopic ultrasound systems: assessment of performance parameters and image quality

Is Accurate N - Staging for Gastric Cancer Possible?

Node stage (N stage) is of paramount importance for gastric cancer staging. Radiologically node status implies detection and characterization of suspect malignant lymph nodes. Clinically it might determine survival and alter therapeutic plans. A number of modalities, including computerized tomography, MRI, PET and endoscopic ultrasound are currently available. Using a multimodality strategy, accuracy ranges between 50-90% across various studies. Specificity and sensitivity varies with respect to method, number of positive lymph nodes, their location and other characteristics. Restaging after neoadjuvant therapy and staging of recurrence presents its own, particular challenges. Each method has its advantages and limitations and none of them alone is adequate enough for staging. While most of them are clinically well established, they are also active research topics. To overcome the aforementioned limitations a multidisciplinary, multimodality approach with emphasis on clinical staging and treatment plans is proposed.

Can visual analogue scale be used in radiologic subjective image quality assessment?

BACKGROUND

Assessment of qualitative or subjective image quality in radiology is traditionally performed using a fixed-point scale even though reproducibility has proved challenging.

OBJECTIVE

Image quality of 3-T coronary magnetic resonance (MR) angiography was evaluated using three scoring methods, hypothesizing that a continuous scoring scale like visual analogue scale would improve the assessment.

MATERIALS AND METHODS

Adolescents corrected for transposition of the great arteries with arterial switch operation, ages 9-15 years (n=12), and healthy, age-matched controls (n=12), were examined with 3-D steady-state free precession magnetic resonance imaging. Image quality of the coronary artery origin was evaluated by using a fixed-point scale (1-4), visual analogue scale of 10 cm and a visual analogue scale with reference points (figurative visual analogue scale). Satisfactory image quality was set to a fixed-point scale 3=visual analogue scale/figurative visual analogue scale 6.6 cm. Statistical analysis was performed using Cohen kappa coefficient and agreement index.

RESULTS

The mean interobserver scores for the fixed-point scale, visual analogue scale and figurative visual analogue scale were, respectively, in the left main stem 2.8, 5.7, 7.0; left anterior descending artery 2.8, 4.7, 6.6; circumflex artery 2.5, 4.5, 6.2, and right coronary artery 3.2, 6.3, 7.7. Scoring with a fixed-point scale gave an intraobserver κ of 0.52-0.77 while interobserver κ was lacking. For visual analogue scale and figurative visual analogue scale, intraobserver agreement indices were, respectively, 0.08-0.58 and 0.43-0.71 and interobserver agreement indices were up to 0.5 and 0.65, respectively.

CONCLUSION

Qualitative image quality evaluation with coronary 3-D steady-state free precession MR angiography, using a visual analogue scale with reference points, had better reproducibility compared to a fixed-point scale and visual analogue scale. Image quality, being a continuum, may be better determined by this method.

Linear-array EUS improves detection of pancreatic lesions in high-risk individuals: a randomized tandem study

BACKGROUND

Studies comparing linear and radial EUS for the detection of pancreatic lesions in an asymptomatic population with increased risk for pancreatic cancer are lacking.

OBJECTIVES

To compare pancreatic lesion detection rates between radial and linear EUS and to determine the incremental diagnostic yield of a second EUS examination.

DESIGN

Randomized controlled tandem study.

SETTING

Five academic centers in the United States.

PATIENTS

Asymptomatic high-risk individuals (HRIs) for pancreatic cancer undergoing screening EUS.

INTERVENTIONS

Linear and radial EUS performed in randomized order.

MAIN OUTCOME MEASUREMENTS

Pancreatic lesion detection rate by type of EUS, miss rate of 1 EUS examination, and incremental diagnostic yield of a second EUS examination (second-pass effect).

RESULTS

Two hundred seventy-eight HRIs were enrolled, mean age 56 years (43.2%), and 90% were familial pancreatic cancer relatives. Two hundred twenty-four HRIs underwent tandem radial and linear EUS. When we used per-patient analysis, the overall prevalence of any pancreatic lesion was 45%. Overall, 16 of 224 HRIs (7.1%) had lesions missed during the initial EUS that were detected by the second EUS examination. The per-patient lesion miss rate was significantly greater for radial followed by linear EUS (9.8%) than for linear followed by radial EUS (4.5%) (P = .03). When we used per-lesion analysis, 73 of 109 lesions (67%) were detected by radial EUS and 99 of 120 lesions (82%) were detected by linear EUS (P < .001) during the first examination. The overall miss rate for a pancreatic lesion after 1 EUS examination was 47 of 229 (25%). The miss rate was significantly lower for linear EUS compared with radial EUS (17.5% vs 33.0%, P = .007).

LIMITATIONS

Most detected pancreatic lesions were not confirmed by pathology.

CONCLUSION

Linear EUS detects more pancreatic lesions than radial EUS. There was a "second-pass effect" with additional lesions detected with a second EUS examination. This effect was significantly greater when linear EUS was used after an initial radial EUS examination.

Assessing the imaging capabilities of radial mechanical and electronic echo-endoscopes using the resolution integral

Over the past decade there have been significant advances in endoscopic ultrasound (EUS) technology. Although there is an expectation that new technology will deliver improved image quality, there are few methods or phantoms available for assessing the capabilities of mechanical and electronic EUS systems. The aim of this study was to investigate the possibility of assessing the imaging capability of available EUS technologies using measurements of the resolution integral made with an Edinburgh Pipe Phantom. Various radial EUS echo-endoscopes and probes were assessed using an Edinburgh Pipe Phantom. Measurements of the resolution integral (R), depth of field (LR) and characteristic resolution (DR) were made at all operating frequencies. The mean R value for Fuji miniprobes was 16.0. The GF-UM20 and GF-UM2000 mechanical radial scopes had mean R values of 24.0 and 28.5, respectively. The two electronic radial echo-endoscopes had similar mean R values of 34.3 and 34.6 for the Olympus GF-UE260 and Fujinon EG-530 UR scopes, respectively. Despite being older technology, the mechanical GF-UM2000 scope had superior characteristic resolution (DR), but could not compare with the depths of field (LR) delivered by the current generation of electronic radial scopes, especially at the standard operating frequencies of 7.5 and 12 MHz.

For biliary dilatation, a negative endosonography needs additional image studies in weight loss suggesting malignancy

BACKGROUND AND AIM

Biliary dilatation frequently raises concerns about the possibility of pancreatobiliary diseases. This study assessed the etiologic yield of endosonography (EUS) in this situation.

METHODS

A retrospective review was completed with 163 consecutive patients who had undergone EUS for a dilated common bile duct (CBD) without definite pathology on ultrasonography.

RESULTS

Binary logistic regression analysis disclosed that malignancy was positively related to weight loss and was inversely related to abdominal pain; nevertheless, choledocholithiasis was positively related to fever and elevated carbohydrate antigen 19-9 (p < 0.05). The accuracy of EUS was 95.1 % (155/163) for overall cause of biliary dilatation, 100 % (73/73) for no pathological finding, 96.3 % (26/27) for ampullary cancer, 84.6 % (11/13) for pancreatic cancer, 40.0 % (2/5) for CBD cancer, and 92.6 % (25/27) for choledocholithiasis, respectively. The accuracy of EUS decreased in the presence of malignancy (86.7 %, 39/45 vs. 98.3 %, 116/118, p = 0.006). EUS missed three CBD cancers, two pancreatic cancers, and one ampullary cancer; however, the diagnosis was rescued by computed tomography in two pancreatic cancers and one CBD cancer.

CONCLUSIONS

EUS is accurate in patients with fever suggestive of choledocholithiasis. However, a negative EUS finding should call for additional image studies in patients with weight loss suggestive of malignancy.

The diagnostic accuracy and strength of agreement between endoscopic ultrasound and histopathology in the staging of ampullary tumors

AIM

Ampullary tumors are rare. Reports on ampullary tumor staging are heterogeneous and combine both periampullary and ampullary tumors. This study assessed the performance of endoscopic ultrasound (EUS) in the local staging of ampullary tumors only.

METHODS

Data were collected retrospectively. We included patients with an ampullary tumor who underwent EUS and surgical resection. Tumor (T) and nodal (N) TNM staging for EUS and histopathological (HP) staging were compared.

RESULTS

From 2009 to 2010, a total of 79 patients with ampullary tumors were identified. Of these, 26 had both EUS and Whipple's surgery and were included (28 did not undergo resection, 13 had palliative surgery only and 12 had resection without EUS). For T staging by HP, there were 2 (7.7 %) T1, 11 (42.3 %) T2, 12 (46.2 %) T3 and 1 (3.8 %) T4 tumors. The accuracy of EUS T staging was 73.1 % with a Kappa value of 0.564 (p < 0.0001). The sensitivity, specificity, positive predictive value (PPV), negative predictive values (NPV) of EUS, respectively were 50.0 %, 91.7 %, 33.3 % and 95.7 % for T1 tumors; 81.8 %, 80.0 %, 75.0 % and 85.7 % for T2; 75.0 %, 92.9 %, 90.0 % and 81.3 % for T3 tumors. For N staging by HP, 17 (65.4 %) were N0 and 9 (34.6 %) N1. The N staging diagnostic accuracy was 80.8 % with a Kappa value of 0.586 (p = 0.003). The sensitivity, specificity, PPV, NPV for N0 disease were 82.4 %, 77.8 %, 87.5 % and 70.0 %, respectively while for N1 they were 77.8 %, 82.4 %, 70.0 % and 87.5 %, respectively.

CONCLUSIONS

EUS had a moderate strength of agreement with histopathology for both T and N staging, and a high diagnostic accuracy for nodal staging.

A comparison of electronic radial and curvilinear endoscopic ultrasonography in the detection of pancreatic malignant tumor

OBJECTIVE

There is no comparative study of electronic radial endoscopic ultrasonography (ER-EUS) and electronic curvilinear EUS (EC-EUS). The aim of this study was to compare the accuracy of ER-EUS and EC-EUS for detecting pancreatic malignancies.

METHODS

This was a retrospective review of the patients who had EUS assessment from September 2008 to December 2011 for suspicious pancreatic tumors. Sensitivity, specificity, and area under the ROC curve to detect pancreatic malignancies were calculated and compared between the ER-EUS and EC-EUS cohort. The final diagnosis of pancreatic malignancy was based on pathology, or the consensus of patient's clinical course and multimodal imaging tests.

RESULTS

Two hundred twenty-one patients were included and divided into two cohorts: ER-EUS (n = 139) and EC-EUS (n = 82) cohorts. With propensity score matching method, 70 cases in each cohort were selected for the comparison. There was no significant difference in sensitivity, specificity, and area under the ROC curve to detect pancreatic malignancy between ER-EUS and EC-EUS cohort (88.5 vs. 100%, 88.6 vs. 90.9%, 0.8855 vs. 0.9545).

CONCLUSION

ER-EUS and EC-EUS provided similar accuracy for the detection of pancreatic malignancies. In view of similar diagnostic results of ER-EUS and EC-EUS for the detection of pancreatic malignancy, and the advantage of being able to perform FNA with EC-EUS, EC-EUS may be the preferred choice.

Characterization of the pancreas in vivo using EUS spectrum analysis with electronic array echoendoscopes

BACKGROUND

Spectral analysis of the radiofrequency (RF) signals that underlie grayscale EUS images has been used to provide quantitative, objective information about tissue histology.

OBJECTIVE

Our purpose was to validate RF spectral analysis as a method to distinguish between chronic pancreatitis (CP) and pancreatic cancer (PC).

DESIGN AND SETTING

A prospective study of eligible patients was conducted to analyze the RF data obtained by using electronic array echoendoscopes.

PATIENTS

Pancreatic images were obtained by using electronic array echoendoscopes from 41 patients in a prospective study, including 15 patients with PC, 15 with CP, and 11 with a normal pancreas.

MAIN OUTCOME MEASUREMENTS

Midband fit, slope, intercept, correlation coefficient, and root mean square deviation from a linear regression of the calibrated power spectra were determined and compared among the groups.

RESULTS

Statistical analysis showed that significant differences were observable between groups for mean midband fit, intercept, and root mean square deviation (t test, P < .05). Discriminant analysis of these parameters was then performed to classify the data. For CP (n = 15) versus PC (n = 15), the same parameters provided 83% accuracy and an area under the curve of 0.83.

LIMITATIONS

Moderate sample size and spatial averaging inherent in the technique.

CONCLUSIONS

This study shows that mean spectral parameters of the backscattered signals obtained by using electronic array echoendoscopes can provide a noninvasive method to quantitatively discriminate between CP and PC.