Ultrasound of superficial lymph nodes

US is a powerful tool for characterization of superficial lymph nodes. Unlike other imaging techniques like CT and MRI, which mainly depend on size for differential diagnosis, US can evaluate important parameters such as shape, margins, internal structure and abnormal vascularization. It has the advantage of showing early subtle findings of neoplastic involvement like asymmetric thickening and focal lobulations in the cortex, as well as late findings such as diffuse cortical thickening and absence of hilum. It is possible to evaluate the heterogeneous inner structure due to necrosis, unsharp or irregular borders due to extracapsular spread and abnormal vascularization with multiple subcapsular feeding vessels due to tumor angiogenesis. The advances in US technology like high-resolution transducers, power Doppler function and contrast agents have all contributed to the well established role of US in the evaluation of lymph nodes. This article mainly focuses on the sonographic criteria for differential diagnosis of normal, reactive, inflammatous and neoplastic lymph nodes as well as examination techniques in the neck, axilla, internal mammary and inguinal regions and indications in various clinical settings.     

Sonography of neck masses in children

The sonograms and medical records of 49 patients were reviewed to determine if there is a characteristic sonographic appearance for certain neck masses. Neck masses included: inflammatory masses (12), noninflammatory masses (23), and thyroid masses (14). Four entities including thyroglossal duct cyst, fibromatosis colli, cystic hygroma, and multiple lymphadenopathy showed characteristic sonographic appearance. Thyroglossal duct cysts were seen as midline or slightly off midline cystic masses. A sinus tract extending superiorly was nicely demonstrated in one patient. The mass in fibromatosis colli (neonatal torticollis) appeared as a well defined mass clearly within the sternocleidomastoid muscle, uniformly echogenic, but less echogenic than the normal surrounding muscle, without good through-transmission. A cystic or primarily cystic mass with linear septations was the characteristic finding of the cystic hygroma. Multiple lymphadenopathy demonstrated multiple discrete, oval, relatively hypoechoic masses along the cervical lymphatic chain. The sonographic appearance of inflammatory masses was variable, being either inhomogeneously echogenic or of mixed echogenicity. Hemangiomas were either echogenic with cystic vascular spaces or linear septations or relatively homogeneously echogenic. Intrinsic thyroid masses could be distinguished from extrinsic masses in most cases. The demonstration of calcification in a mass was useful in narrowing the differential diagnosis. Although it is not a specific finding, the presence of calcification highly suggests a neoplastic lesion, particularly neuroblastoma or teratoma. Not only can the location, extent, and internal characteristics of a mass be determined, but in certain entities, the sonographic appearance is characteristic and an accurate diagnosis can be made.     

Sonographic evaluation of inferior vena caval obstruction: correlative study with vena cavography

Sonographic findings of obstruction of the inferior vena cava (IVC) in 14 cases are described and correlated with venographic findings. The causes of the obstruction were membrane (five cases), thrombosis (three), and intraluminal tumor invasion by hypernephroma, hepatoma, and adrenal carcinoma in six. Sonographic examination revealed highly echogenic segmental obliteration or membrane in membranous obstruction and echogenic intraluminal mass in thrombotic occlusion. Absence of an identifiable patent lumen in a technically satisfactory study was another finding in thrombotic obstruction. On real-time sonograms, the normal respiratory changes of the IVC were absent when there was complete occlusion. Transhepatic collaterals, patency of other segments of the IVC, and associated malignancy were additional sonographic findings. Comparison to venography suggested that in addition to ease and safety, sonography has advantages in delineation of the cephalad extent of occlusion, dynamic evaluation of the IVC below the obstruction, and the simultaneous evaluation of adjacent organs.     

Differentiation between benign and metastatic cervical lymph nodes with ultrasound

Objective:

The differentiation between benign and metastatic lymph nodes with ultrasound (US) is based primarily on the evaluation of size, shape, margin and internal echo structure. The aim of this study is to determine whether these parameters are reliable indicators and to correlate internal echo structure and histopathological findings.

Materials and Methods:

Seventy-one nodes in 21 patients with pathologically proven oral squamous cell carcinoma were examined. The shortest diameter, the short/long diameter ratio (S/L ratio), margins and internal echo structure of the lymph node were evaluated by US. The internal echo structure was divided into six patterns: homogeneous hypoechoic, homogeneous hyperechoic, heterogeneous, eccentric hyperechoic, centric hyperechoic and anechoic pattern. In addition, internal echo structure was correlated with histopathological findings.

Results:

In 71.4% of the metastatic nodes, the shortest diameter was more than 10 mm and the S/L ratio was higher than that of benign nodes (average 0.71). Eleven (84.6%) of the 13 lymph nodes with irregular margins were metastatic. Heterogeneous and anechoic patterns were observed in metastatic nodes, whereas homogeneous hypoechoic and eccentric hyperechoic patterns were present in benign nodes. On ultrasonography with the corresponding histopathological findings, echogenic areas in the homogeneous hyperechoic, heterogeneous and centric hyperechoic patterns of metastatic nodes proved to be necrosis or fibrosis. Eccentric hyperechoic areas in benign nodes corresponded to the hilus and surrounding fatty tissue.

Conclusions:

The shortest diameter, S/L ratio, margin and internal echo structure were considered to be critical indicators to differentiate between benign and metastatic nodes. Secondary changes caused by tumour infiltration, necrosis, or fibrosis should be assessed when metastatic lymph nodes are differentiated from benign ones by internal echo structure.     

Vascularity and grey-scale sonographic features of normal cervical lymph nodes: variations with nodal size

AIM: This study was undertaken to investigate variations in the vascularity and grey-scale sonographic features of cervical lymph nodes with their size. MATERIALS AND METHODS: High resolution grey-scale sonography and power Doppler sonography were performed in 1133 cervical nodes in 109 volunteers who had a sonographic examination of the neck. Standardized parameters were used in power Doppler sonography. RESULTS: About 90% of lymph nodes with a maximum transverse diameter greater than 5 mm showed vascularity and an echogenic hilus. Smaller nodes were less likely to show vascularity and an echogenic hilus. As the size of the lymph nodes increased, the intranodal blood flow velocity increased significantly (P < 0.05), whereas there was no significant variation in the vascular resistance(P> 0.05). CONCLUSIONS: The findings provide a baseline for grey-scale and power Doppler sonography of normal cervical lymph nodes. Sonologists will find varying vascularity and grey-scale appearances when encountering nodes of different sizes.Ying, M.et al. (2001). Clinical Radiology, 56, 416-419.     

Differentiation of benign from malignant superficial lymphadenopathy: the role of high-resolution US.

Ultrasonography has proved a valuable tool for the detection of enlarged lymph nodes; however, differentiation between benign and malignant nodal disease remains a problem. High-frequency probes with improved spatial and contrast resolution display superficial nodes to advantage and also show the internal structure of the nodes. Ninety-four superficial nodes in patients with suspected nodal disease were examined by using 7.5-MHz probes to evaluate longitudinal-transverse diameter ratio (L/T), the central hilus, cortical widening, and size. Histologic diagnosis was obtained after sonographic examination in 73 nodes (five reactive nodes, 35 primary nodal malignancies, and 33 nodal metastases). The remaining 21 nodes regressed after either antibiotic or no therapy. Marked differences were observed among the proportions of benign and malignant nodes in terms of L/T, hilus, and cortex; the latter two structures, however, must be interpreted together. Eccentric cortical widening was seen in only malignant nodes. The distribution of nodal size was not significantly (P greater than .1) different for benign and malignant nodes. No differences were observed between primary and secondary nodal malignancies. The sonographic criteria evaluated in this study assist in the differentiation of benign from malignant superficial lymph nodes.     

Hematosalpinx in tubal pregnancy: sonographic-pathologic correlation

Review of sonograms in 84 patients with documented tubal pregnancies yielded 15 cases with discrete, diffusely echogenic, adnexal masses (18%). All these cases were proven at surgery to represent hematosalpinx containing clotted blood. The characteristic sonographic findings in these cases enabled an accurate preoperative diagnosis in 12 consecutive patients. Hematosalpinx containing clotted blood was seen as a diffusely echogenic adnexal mass accompanied in most cases by areas of high-intensity echoes. Pelvic hemoperitoneum (five cases) was diffusely echogenic due to clotted blood, and its recognition enabled evaluation of the upper abdomen for extension of hemorrhage. The echogenicity of the adnexal mass and pelvic hematoma was similar to that of the uterus, resulting in obscuration of its contour. The following sonographic features are characteristic of tubal pregnancy in the proper clinical setting: (1) absence of intrauterine gestation; (2) diffusely echogenic adnexal mass with areas of high-intensity echoes; and (3) diffusely echogenic hematoma in the pouch of Douglas.     

Echogenic material in the fetal gallbladder: sonographic and clinical observations.

Obstetric sonograms of 26 fetuses with echogenic material in the gallbladder were reviewed to describe the sonographic findings and clinical significance. Gestational age at the time of diagnosis ranged from 28 to 42 weeks (mean, 36.2 weeks). The echogenic foci were associated with distal shadowing in eight fetuses (30%), comet-tail artifact in nine (35%), and no distal artifact in nine (35%). No hemolytic anemias, other predisposing risk factors, or clinical sequelae associated with biliary tract disease were identified in any of the infants. Postnatal sonographic or pathologic follow-up studies were available in 17 cases. In nine of these 17 infants, the echogenic foci had resolved. In three, the foci have persisted, but none of the children have become symptomatic; the longest period of follow-up with stones still present is 4 1/2 years. Whether all echogenic foci in the fetal gallbladder represent true gallstones remains unknown. Echogenic foci may be seen in the fetal gallbladder during the third trimester. No predisposing fetal risk factors or clinical sequelae were evident in our series. Many echogenic foci, but not all, will resolve.     

Cystic lymph node metastases in papillary thyroid carcinoma

OBJECTIVE: The aim of this study was to illustrate and discuss the sonographic spectrum of surgically proven cystic nodal metastases from papillary thyroid carcinoma. By correlative evaluation of the sonographic imaging findings to gross pathology and histology, our purpose was to provide useful hints to differentiate cystic lymph node metastases from other benign cystic neck lesions such as branchial cysts. MATERIALS AND METHODS: Sonographic examinations of 74 patients (47 women, 27 men; mean age, 49 years) with 97 histologically confirmed cystic lymph nodes metastases from papillary thyroid carcinoma were included in the study. The anatomic relationship of the nodes relative to the primary tumor was recorded, and all cystic nodes were qualitatively categorized as either simple (purely cystic) or complex (thickened outer wall, internal nodules, internal septations, and calcifications). All imaging findings were compared with gross pathologic specimens. RESULTS: Most of the cystic metastases were ipsilateral to the primary tumor (87.8%) and located in the mid or lower jugular chain (73.2%). In 14.9% of all patients, cystic lymph node metastases were the initial manifestation of disease. Only 6.2% of all lymph node metastases were purely cystic (all of these occurred in patients less than 35 years old). Of the 91 complex metastases, a thickened outer wall was present in 35.2% of patients, internal nodules in 42.9%, and internal septations in 57.1%. No calcifications were seen in the 91 complex metastases, and two or more findings were seen in 23.1%. All sonographic findings were verified by surgery. CONCLUSION: In most of the patients, cystic lymph node metastases are characterized sonographically by the presence of a thickened outer wall, internal echoes, internal nodularity, and septations. However, in younger patients, the lymph nodes might appear purely cystic, thereby mimicking branchial cysts and thus requiring biopsy for final diagnosis and therapy planning.     

Cohen ureteral reimplantation: sonographic appearance

The sonographic records of 27 children who underwent a Cohen ureteroneocystostomy were reviewed. In 13 children (48%) sonograms demonstrated an echogenic, nonacoustically shadowing structure at or just above the trigone that was fixed in position within the bladder wall and covered by intact mucosa. This constellation of sonographic findings, which represent the submucosal segment of the reimplanted ureter, produces a "tunnel sign." Awareness of this appearance will enable the sonographer to better evaluate children who have undergone surgical procedures on the bladder.     

Multivariate feature analysis of sonographic findings of metastatic cervical lymph nodes: contribution of blood flow features revealed by power Doppler sonography for predicting metastasis

BACKGROUND AND PURPOSE: Sonographic criteria of the lymph node have been found to be good indicators for metastatic lymph nodes. We determined which sonographic features are most predictive of metastasis in cervical lymph nodes among patients with head and neck cancer. METHODS: Gray-scale and power Doppler sonograms were retrospectively analyzed in 133 cervical lymph nodes (57 metastatic and 76 reactive nodes) from 52 patients with head and neck cancer. The gray-scale sonographic features of the presence or absence of hilar echoes, parenchymal echogenicity, and short and long axis lengths as well as the power Doppler features of normal hilar flow and abnormal parenchymal flow were evaluated. Univariate and multivariate logistic regression analyses were conducted to determine the relative value of each sonographic feature. RESULTS: At univariate analysis, all sonographic features assessed were found to be important. Multivariate analysis, however, suggested that the presence or absence of hilar echoes, increases in short axis length, and the presence of normal hilar flow were the only sonographic features that were predictive of reactive (presence of hilar echoes and hilar flow) and metastatic (increases in short axis length) lymph nodes. Although multivariate analysis did not indicate any significant contribution of the color-flow criteria for predicting metastatic nodes, the color-flow criteria appeared to improve the overall diagnostic accuracy for the less experienced observer. CONCLUSION: The sonographic criteria most predictive of metastatic cervical lymph nodes were absent hilar echoes and increases in short axis length, as assessed by logistic regression analysis. Compared with these gray-scale criteria, color-flow criteria had fewer predictive advantages.     

Abdominal lymph nodes: the echographic evaluation criteria

US patterns of abdominal lymph nodes were investigated in patients with neoplastic and non-neoplastic diseases, and in randomly-chosen subjects with no evidence of any pathologic condition. Major longitudinal diameter (DMax) was statistically evaluated, together with minor transverse diameter (DMin), roundness index (RI), and structural index (IS)-i.e., the presence of a central hyperechoic line (as the US sign of normal lymph node architecture). DMax proved to be useless for distinguishing between groups. The presence of a central hyperechoic line was the most useful parameter, although the extant 3 (DMin, RI, IS) were also useful for distinguishing between groups. By correlating each numerical parameter with the hyperechoic line sign an even better discrimination was obtained. Thus, it can be assumed that only a combined and comprehensive evaluation of the above parameters makes the best criterion to differentiate between neoplastic and non-neoplastic abdominal lymph nodes.     

Papillary process of the caudate lobe of the liver: sonographic appearance

The papillary process of the caudate lobe of the liver may appear separate from the liver and thus mimic lymph nodes or a pancreatic mass. In order to evaluate the sonographic appearance of this anatomic structure, 400 male and female patients with a mean age of 50 years were studied prospectively by means of ultrasound. The papillary process appeared to be separate from the liver on transverse sonograms in 62 patients (15.5%) and had an egg shape with a maximal transverse diameter of 8-39 mm. In all 62 patients, the papillary process appeared above and in front of the common hepatic artery close to the portal vein and pancreatic isthmus. Enlarged papillary processes were more frequently seen in patients with chronic liver disease. Knowledge of the anatomy, sonographic pattern, and vascular relationships of the papillary process enable its correct identification.     

The hyperechogenic liver in children: cause and sonographic appearance

The clinical records of 28 patients seen in one institution during a recent 2 year period who, on sonography, had been identified as having a hyperechogenic (bright) liver were reviewed. Seven children were diagnosed as having metabolic diseases, four were malnourished, four were receiving hyperalimentation, 10 were receiving chemotherapy, and three were undiagnosed. The sonograms of all the patients and the histologic sections on those who had biopsies, were reevaluated in order to assess the sonographic pattern in greater detail, and these findings were correlated with fatty infiltration and fibrosis of the liver. The bright liver corresponded to the pathologic finding of fatty change. This sonographic finding in children is important, as further evaluation (hepatic biopsy with fat stain, enzymatic analyses, amino acid screens) can be suggested to identify underlying metabolic disorders in those not on therapy. Often the complications of metabolic diseases can be prevented or delayed by early diagnosis and appropriate therapy.     

'Pseudocystic' appearance of non-Hodgkin's lymphomatous nodes: an infrequent finding with high-resolution transducers

AIMS: A pseudo-cystic appearance and posterior enhancement are previously reported to be diagnostic sonographic features of lymph node involvement in non-Hodgkin's lymphoma. This study was undertaken to determine whether these ultrasonic features remain with the use of high-resolution transducers.MATERIAL AND METHODS: A review of ultrasound examinations in 32 patients with proven lymphomatous cervical lymphadenopathy (27 non-Hodgkin's lymphoma, five Hodgkin's disease) was performed. A total of 95 lymph nodes were assessed for size, shape, posterior enhancement and internal architecture. All examinations were performed with the same high-resolution transducer and by the same sonologist.RESULTS: Lymphomatous nodes (irrespective of type) are frequently heterogeneous (68-86%), have a micronodular pattern (63-69%) and less commonly demonstrate posterior enhancement (9-26%).CONCLUSION: Using a high-resolution ultrasonic transducer, cervical nodes involved with lymphoma (irrespective of type) commonly demonstrate a heterogeneous micronodular pattern. The pseudocystic appearance of nodes with posterior enhancement in non-Hodgkin's nodes is seen infrequently.     

Small arteries in peripheral lymph nodes: a specific US sign of lymphomatous involvement

Fifty-seven patients with palpably enlarged peripheral lymph nodes underwent detailed ultrasonographic (US) examination with a 5.0-MHz and a 7.5-MHz probe. In 32 of 36 patients with malignant lymphoma (12 with Hodgkin disease, 24 with non-Hodgkin lymphoma) US showed a hypoechoic mass with a centrally located tubular structure. Pathologic examination showed that this structure correlated with small intact arterial vessels encased by confluent lymphomatous masses. This sonographic finding was not seen in patients with carcinomatous metastatic lesions to the lymph nodes (nine patients) or benign lymphadenitis (12 patients). The detection with US of small arteries within enlarged lymph nodes may indicate nodal infiltration by malignant lymphoma.     

Perirenal lucency ("kidney sweat"): a new sign of renal failure.

OBJECTIVE: This study describes a new sonographic finding in renal failure: perirenal lucency, which we call the "kidney sweat" sign. MATERIALS AND METHODS: During 1 year at our institution, 502 renal sonograms were obtained. Sonography evaluated 330 patients with renal failure. All of the examinations were retrospectively analyzed. RESULTS: An extracapsular hypoechoic rim was present in 47 (14%) of the 330 patients with renal failure. The finding, when present, was always bilateral. The hypoechoic rim was not present in the remaining 283 patients with renal failure. Forty (85%) of the 47 patients had kidneys that were hyperechoic compared with the liver. Twenty-eight (60%) of the 47 patients had kidneys that were hyperechoic compared with the spleen. In 15 (32%) of the 47 patients, the kidneys were small. Ascites was present in 11 (23%) of the 47 patients. Of the 283 patients with renal failure whose sonograms did not show the hypoechoic rim, 76 patients had normal sonographic findings. The remaining 207 patients with renal failure who did not show the kidney sweat sign had hydronephrosis, stones, cysts, echogenic kidneys, small kidneys, or ascites. CONCLUSION: An extracapsular hypoechoic rim is found in patients with renal failure. We call this finding "kidney sweat." We believe, but cannot currently prove, that the kidney sweat sign represents edema. It is an additional sonographic finding in patients with renal failure.     

Ruptured gel-filled silicone breast implants: sonographic findings in 19 cases.

OBJECTIVE. The purpose of this study was to describe and illustrate the sonographic appearances of 19 ruptured silicone gel breast implants. MATERIALS AND METHODS. We retrospectively reviewed the sonograms of 16 patients with 19 ruptured silicone gel implants from two institutions. The ruptured implant was confirmed at surgery in 17 cases and by mammographic and clinical findings of a ruptured implant combined with biopsy findings of a silicone granuloma in two cases. Breast sonograms were available for review in all patients. The clinical presentation of each patient was recorded. The sonograms and mammograms were reviewed, and the findings were correlated with the surgical findings. In 16 of the 19 ruptured implants, mammographic findings suggested rupture, including lobulation of the contour of the implant and/or silicone extrusion into the breast parenchyma or axilla. In two ruptured implants, mammographic findings were normal, and in one case, no mammogram was available. In those three patients, palpable masses and clinical findings were suggestive of rupture. RESULTS. Sonography showed a unique echogenic appearance called echo-dense noise, in 17 of the 19 ruptured implants; in 10 of the 17, sonograms showed hypoechoic masses of extruded silicone also. In two ruptured implants, sonograms showed only the hypoechoic masses of extruded silicone gel. CONCLUSION. Our experience suggests that echogenic noise is a unique sonographic sign of ruptured silicone gel breast implants and may be caused by phase aberration related to the speed of sound being slower in silicone than in soft tissue.     

腋窝内脂肪浸润淋巴结的X线表现

目的认识日常工作中乳腺X线检查中腋窝内脂肪浸润淋巴结的发生情况及其X线表现.资料与方法回顾性分析436例乳腺X线检查中MLO位片上两侧腋窝内脂肪浸润淋巴结的检出率及其X线表现,并与同时见到的无脂肪浸润淋巴结作了比较.结果 178例(40.83%)见有腋窝淋巴结,其中104例(58.4%)有脂肪浸润,35例(19.7%)无脂肪浸润,两者共存者40例(22.5%),有脂肪浸润者显著多于无脂肪浸润者(P＜0.01).在形态上,有脂肪浸润者中多呈有特征性的中央或一侧较低密度的卵圆形或新月形,其边缘多部分或全部边缘不清(86.1%).有脂肪浸润者最大可达35 mm,其长径和短径分别平均为13.8 mm和7.2 mm,都要大于无脂肪浸润者,后者分别为7 mm和5 mm(P＜0.01).结论腋窝内含脂肪淋巴结很常见,有一定特征性X线表现,认识它们有利于鉴别诊断,以免误诊.     

Neonatal ovarian cysts: sonographic-pathologic correlation

The authors reviewed the prenatal (11 infants) and postnatal (17 infants) sonograms and the clinical, surgical, and pathologic findings in 17 infants with an ovarian cyst to determine the sonographic features and natural history of neonatal ovarian cysts. An uncomplicated cyst (nontwisted, nonhemorrhagic) was completely anechoic and the cyst wall was imperceptible with sonography (five cases). A twisted or hemorrhagic cyst was cystic with a fluid-debris level, cystic with a retracting clot, septated with or without internal echoes, or solid (12 cases). These complicated cysts contained liquid and/or organized hematoma. Eleven of the 12 complicated cysts had a thin, highly echogenic wall. Cyst torsion commonly occurred in utero and could be diagnosed on prenatal sonograms by a typical sonographic appearance (eight cases). All of these infants were asymptomatic after birth. Four infants with hemorrhagic or twisted cysts were symptomatic. All cysts except one that resolved spontaneously were treated surgically, including three twisted cysts that showed no change in size over a 1-8-month interval. All of the cysts were of follicular origin.