Echo pattern of lymph nodes in colorectal cancer: an in vitro study

EFSUMB Recommendations for Gastrointestinal Ultrasound Part 3: Endorectal, Endoanal and Perineal Ultrasound

This article represents part 3 of the EFSUMB Recommendations and Guidelines for Gastrointestinal Ultrasound (GIUS). It provides an overview of the examination techniques recommended by experts in the field of endorectal/endoanal ultrasound (ERUS/EAUS), as well as perineal ultrasound (PNUS). The most important indications are rectal tumors and inflammatory diseases like fistula and abscesses in patients with or without inflammatory bowel disease (IBD). PNUS sometimes is more flexible and convenient compared to ERUS. However, the technique of ERUS is quite well established, especially for the staging of rectal cancer. EAUS also gained ground in the evaluation of perianal diseases like fistulas, abscesses and incontinence. For the staging of perirectal tumors, the use of PNUS in addition to conventional ERUS could be recommended. For the staging of anal carcinomas, PNUS can be a good option because of the higher resolution. Both ERUS and PNUS are considered excellent guidance methods for invasive interventions, such as the drainage of fluids or targeted biopsy of tissue lesions. For abscess detection and evaluation, contrast-enhanced ultrasound (CEUS) also helps in therapy planning.

Digital Rectal Examination and Transrectal Ultrasonography in Staging of Rectal Cancer

Staging of rectal carcinoma before surgical treatment was performed in a prospective blind study, comparing digital rectal exploration and transrectal linear ultrasonography (TRUS) with the resulting pathological examination. TRUS underestimated depth of penetration in 3 of 33 patients and overestimation resulted in 9 of 74. The figures for digital examination were 5 of 18 and 20 of 76, respectively. Penetration of the rectal wall was correctly identified in 56 of 61 patients by digital examination and in 59 of 61 by TRUS. Specimens without penetration of the rectal wall were identified in 26 of 33 patients by TRUS, but in not more than 13 of 33 by digital examination. Regional lymph node metastases were present in 19 patients; none were diagnosed by digital examination, but TRUS identified 11 of the 19. It is concluded that TRUS will result in more patients having the possibility of local surgery for cure.

Dual-Energy CT of Rectal Cancer Specimens: A CT-based Method for Mesorectal Lymph Node Characterization

BACKGROUND

An accurate method to assess malignant lymph nodes in the mesorectum is needed. Dual-energy CT scans simultaneously with 2 levels of energy and thereby provides information about tissue composition based on the known effective Z value of different tissues. Each point investigated is represented by a certain effective Z value, which allows for information on its composition.

OBJECTIVE

We wanted to standardize a method for dual-energy scanning of rectal specimens to evaluate the sensitivity and specificity of benign versus malignant lymph node differentiation. Histopathological evaluation of the nodes was our reference.

DESIGN

This was a descriptive and prospective study.

SETTINGS

Seventeen rectal specimens were examined in 2 series. The first series was conducted with 3 specimens from patients who were not given perioperative contrast; 3 had iodine-based contrast and 3 had gadolinium-based contrast. We concluded that iodine was the contrast agent of choice and therefore included 8 more patients in a second series, given iodine-based contrast, for further analysis.

PATIENTS

Quantitative imaging data were collected from 197 individual lymph nodes from 17 specimens, from patients with rectal cancer.

MAIN OUTCOME MEASURES

We measured accuracy of differentiating benign from malignant lymph nodes by investigating the following: 1) gadolinium, iodine, and water concentrations in lymph nodes; 2) dual-energy ratio; 3) dual-energy index; and 4) effective Z value.

RESULTS

Optimal discriminations between benign and malignant lymph nodes were obtained using the following cutoff values: 1) effective Z at 7.58 (sensitivity, 100%; specificity, 90%; and accuracy, 93%), 2) dual-energy ratio at 1.0 × 10 (sensitivity, 96%; specificity, 87%; and accuracy, 90%), 3) dual-energy index at 0.03 (sensitivity, 97%; specificity, 88%; and accuracy, 91%), and 4) iodine concentration at 2.58 μg/mL (sensitivity, 86%; specificity, 92%; and accuracy, 89%).

LIMITATIONS

The investigation is conducted on isolated surgical specimens from rectal cancer operations.

CONCLUSIONS

Dual-energy CT can be performed on rectal specimens. The discrimination between benign and malignant nodes seems promising when using iodine as contrast.

Nodal staging in rectal cancer

Rectal cancer is common and nodal disease is an independent adverse prognostic factor for patient survival. Accurate demonstration of the presence and location of nodal disease preoperatively may influence management strategies. In this article we review the pathways of nodal spread in rectal cancer and assessment of nodal disease using sonography, CT, and MRI. The use of morphological criteria instead of size criteria has been shown to improve nodal staging by MRI. The potential role of magnetic resonance lymphography and PET imaging in further improving nodal staging accuracy is discussed.

Diagnosis of Peripheral Lung Cancer With Three Echoic Features Via Endobronchial Ultrasound

BACKGROUND

Endobronchial ultrasonography (EBUS) is useful in localizing peripheral lung lesions. Previous reports have revealed that several characteristic echoic patterns correlate well with the histopathologic findings of benign and malignant lesions. Therefore, EBUS may be also useful in the differential diagnosis of malignant lesions of the lung.

OBJECTIVE

To assess the feasibility of EBUS in the differential diagnosis between malignant and benign lesions by the following three characteristic echoic features indicating malignancy: continuous margin; absence of a linear-discrete air bronchogram; and heterogeneous echogenicity.

METHOD

EBUS images from 224 patients who undergone bronchoscopy for a peripheral lung lesion were analyzed. The sensitivity and specificity for each echoic feature or in combination in diagnosing malignancy or benignity were determined.

RESULT

Continuous margin, absence of linear-discrete air bronchogram, and heterogeneous echogenicity are three echoic features indicating malignancy. The absence of linear-discrete air bronchogram has the highest sensitivity in the diagnosis of malignancy (91.9%), but the lowest specificity (62.4%). By contrast, a well-defined margin has the highest specificity (93.1%), but the lowest sensitivity (27.6%). The sensitivity and specificity for heterogeneous echogenicity are intermediate (65.0% and 90.1%, respectively). The negative predictive value for the malignancy of a lesion with none of these three echoic features is 93.7%. The positive predictive value for malignancy of a lesion with any two of the three echoic features is 89.2%.

CONCLUSION

These results indicate that EBUS is useful as an adjunct in lung cancer diagnosis, especially when peripheral lung lesions are not visible in traditional bronchoscopy.

Ultrasonography of the medial iliac lymph nodes in the dog

Sixty-one medial iliac lymph nodes of 38 different dogs (eight with adenocarcinoma of the apocrine glands of the anal sac, 13 with multicentric lymphoma, six with multicentric lymphoma but in clinical remission, and 11 control dogs) were evaluated to assess the ability of ultrasound to identify and interrogate these lymph nodes across the different groups and to differentiate these groups using different sonographic parameters. Ultrasound proved to be useful to assess canine medial iliac lymph nodes. An increase in size or number of detected lymph nodes or finding rounder or heterogeneous lymph nodes could differentiate lymph nodes of dogs of the control group from lymph nodes of dogs with lymphoma or an adenocarcinoma of the apocrine glands of the anal sac. Subcategories of malignancy could not be differentiated. More studies need to be performed, both with patients with reactive lymph nodes and also focusing on other canine superficial lymph nodes, before generalizing the results of this study to other areas or diseases.

Computer-assisted analysis of lymph nodes detected by EUS in patients with esophageal carcinoma

BACKGROUND

EUS determination of lymph nodal spread of intestinal cancer based on imaging alone is problematic. A noninvasive, reliable means of determining tumor spread to lymph nodes is desirable. This study investigated the feasibility of a computer-assisted evaluation of lymph nodes detected by EUS in patients with esophageal carcinoma.

METHODS

Images were obtained during EUS of esophageal lesions and correlated with histopathologic findings after esophagectomy. Sonographic features of echogenicity, whole-node heterogeneity, and regional variability were assessed by computerized image analysis in patients with benign versus malignant lymphadenopathy.

RESULTS

Malignant lymph nodes were hypoechoic compared with benign lymph nodes (p < 0.04). Whole lymph node heterogeneity was increased in malignant lymph nodes (p < 0.004). Regional variability was greater for benign lymph nodes.

CONCLUSIONS

These data support the feasibility of a computer-assisted system for analysis of lymph node metastasis in patients with esophageal carcinoma. Further refinements of such a system could increase the accuracy of EUS staging of tumors.

Limitation of endorectal ultrasonography: what does a low lesion more than 5 mm in size correspond to histologically?

PURPOSE

The accuracy of diagnosis of metastatic lymph nodes for rectal carcinoma has not improved. A low echoic lesion more than 5 mm in size detected by endorectal ultrasonography is preoperatively assessed as a metastatic lymph node. What does a low echoic lesion more than 5 mm in size correspond to histologically?

METHODS

Forty-seven patients with lower rectal carcinoma (Term I, 1986-1990) and 48 patients with lower rectal carcinoma (Term II, 1991-1995) undergoing endorectal ultrasonography were reviewed. Surgically resected rectal specimens from 40 patients with rectal carcinoma underwent ultrasonography. Low echoic lesions more than 5 mm in size were taken from resected specimens and were stained with hematoxylin, followed by histologic examination.

RESULTS

The accuracy of diagnosis of metastatic lymph nodes of Term II was not higher than that of Term I. Twenty-five low echoic lesions were detected by ultrasonography using 40 resected specimens. Seventeen of these 25 lesions (68 percent) were histologically confirmed to be metastatic lymph nodes. One of 25 (4 percent) was found to be lymphadenitis with no metastasis. Among the 25 lesions, 5 (20 percent) were histologically confirmed to be tumor deposits, 2 (8 percent) fatty tissue, and 22 (88 percent) carcinoma.

CONCLUSIONS

Low echoic lesions were histologically confirmed to be tumor deposits (20 percent) and metastatic lymph nodes (68 percent). Although these data show deficiencies and limitations of the accuracy of endorectal ultrasonography, they compare favorably with other series, and no other current technology can show similar accuracy.

Small spot sign of rectal carcinoma by endorectal ultrasonography: histologic relation and clinical impact on postoperative recurrence

PURPOSE

We observed small spots at the margin of rectal carcinomas on endorectal ultrasonography. Our aim was to study the relationship between ultrasonographic evidence of these spots and histologic characteristics of disease and postoperative recurrence.

PATIENTS AND METHODS

The study group comprised 55 patients, 36 men and 19 women, with rectal carcinoma as confirmed by biopsy. The patients were followed up at three-month intervals for six months to three years and six months after the operation. Endorectal ultrasonography was performed in the usual manner. Surgically resected specimens were stained with hematoxylin and eosin and histologically examined. Vessel invasion was graded from 0 (not invasive) to 3 (most invasive).

RESULTS

Among the 55 patients studied, 3 had Stage T2,N0,M0 rectal carcinomas and 35 had Stage T3,N0,M0 carcinomas, 5 (14.3 percent) of whom had echographic evidence of small spots. Thirteen patients had Stage T3,N1/2,M0 carcinomas, comprising 12 (92.3 percent) with small spots, and four patients had T3,N1/2,M1 carcinomas, all with small spots. Vessel invasion of Grade 2 or higher was observed around the carcinomas in 20 of 21 patients who had small spots. Ten of 13 patients with many spots at the margin of the carcinoma (a spot grade of ++) histologically had marked venous or lymphatic invasion (an invasion Grade 3). The presence of small spots was closely associated with massive venous or lymphatic invasion (a vessel invasion grade of 2 or more). Four patients had synchronous liver metastases, and small spots were found in all four. Distant metastases and local recurrence were found in 11 of 21 patients with small spots. We found no recurrence in any patient without small spots on endorectal ultrasonography.

CONCLUSIONS

Small spots indicate the presence of massive venous or lymphatic invasion and a high risk of postoperative recurrence.

Endosonography for preoperative staging of rectal tumours

PURPOSE

The aim of this study was to evaluate the use of rectal endosonography for preoperative staging of tumour extension and lymph node involvement in rectal tumours.

MATERIAL AND METHODS

Over a 4-year period 100 patients with rectal tumours were studied with sonography using 7 MHz endoprobes. Tumour spread was assessed according to the TNM classification, and the number and maximum size of perirectal lymph nodes were registered. The sonographic findings were compared with the surgical and histological findings.

RESULTS

The overall accuracy of endosonography in assessing local tumour extension was 85% (76-91%; 95 percent confidence limits). T4 tumours with a large contact surface to an adjacent organ tended to be nonresectable. Lymph node assessment could be made in 81 patients who underwent radical resection: sonography showed lymph nodes in 49 patients, 30 of whom had nodal metastases; the histological examination showed lymph nodes in the remaining 32 patients, 8 of whom had nodal metastases. The number of lymph nodes at the histological examination was markedly higher than the number depicted by preoperative ultrasound.

CONCLUSION

This study confirmed the use of endoluminal ultrasound in the preoperative evaluation of local tumour spread. However, endosonographic assessment of perirectal nodal involvement seems to be too unreliable to be used for the preoperative selection of patients.

Staging and surgery for colorectal cancer

Staging of colorectal cancer has become increasingly important to select groups of patients for limited or more extensive surgery, and for adjuvant radiotherapy and chemotherapy. The main treatment is still surgery, but subgroups may benefit from adjuvant therapy, even accepting additional side effects. Accurate staging is necessary to define different treatment groups. A critical review is given of the present methods of clinicopathological staging.