Lymphography--current role in oncology

Effectiveness of therapeutic lymphography on lymphatic leakage

BACKGROUND

The number of conventional lymphographies has declined markedly since the introduction of cross-sectional imaging techniques. Nevertheless, lymphography has a high potential as a reliable method to visualize and directly occlude lymphatic leaks. When used as a distinct radiological procedure with the intention to treat, this application can be described as therapeutic lymphography.

PURPOSE

To investigate if therapeutic lymphography is a reliable method to treat lymphatic leakage when conservative treatment fails and to investigate which parameters influence the success rate.

MATERIAL AND METHODS

Between August 1995 and January 2008, 50 patients with lymphatic leakage in form of chylothorax, chylous ascites, lymphocele, and lymphatic fistulas underwent conventional therapeutic lymphography after failure of conservative therapy. Of these 50 patients, seven could not be statistically evaluated in our retrospective study: one patient died of cancer 1 day after lymphography, and six were excluded due to various technical problems. The remaining 43 patients were evaluated. Therapeutic success was evaluated and correlated to the volume of lymphatic leakage (more or less than 500 mL/day), as assessed by drainage.

RESULTS

In nearly 79% of patients, the location of the leak could be detected, and surgical intervention could be planned when therapeutic lymphography failed. Due to the irrigating effect of the contrast medium (lipiodol), the lymphatic leak could be completely occluded in 70% of patients when the lymphatic drainage volume was less than 500 mL/day. Even when lymphatic drainage was higher than 500 mL/day, therapeutic lymphography was still successful in 35% of the patients. The overall success rate in patients with failed conservative treatment was 51%. Success did not depend on other factors such as age and sex, cause of lymph duct damage, or time elapsed between lymphatic injury and intervention.

CONCLUSION

Therapeutic lymphography is an effective method in the treatment of lymphatic leakage when conservative therapy fails. The volume of lymphatic drainage per day is a significant predictor of the therapeutical success rate.

Multimodal nanoprobes for radionuclide and five-color near-infrared optical lymphatic imaging

Current contrast agents generally have one function and can only be imaged in monochrome; therefore, the majority of imaging methods can only impart uniparametric information. A single nanoparticle has the potential to be loaded with multiple payloads. Such multimodality probes have the ability to be imaged by more than one imaging technique, which could compensate for the weakness or even combine the advantages of each individual modality. Furthermore, optical imaging using different optical probes enables us to achieve multicolor in vivo imaging, wherein multiple parameters can be read from a single image. To allow differentiation of multiple optical signals in vivo, each probe should have a close but different near-infrared emission. To this end, we synthesized nanoprobes with multimodal and multicolor potential, which employed a polyamidoamine dendrimer platform linked to both radionuclides and optical probes, permitting dual-modality scintigraphic and five-color near-infrared optical lymphatic imaging using a multiple-excitation spectrally resolved fluorescence imaging technique.

MR imaging in ovarian cancer

Magnetic resonance (MR) imaging is increasingly being used in patients with gynaecological disorders due to its high contrast resolution compared to computed tomography (CT) and ultrasound. In women presenting with an adnexal mass, ultrasound remains the primary imaging modality in the detection and characterisation of such lesions. However, in recent years overwhelming evidence has accumulated for the use of MR imaging in patients with indeterminate adnexal masses particularly in younger women and where disease markers are unhelpful. In staging ovarian cancer and for evaluating therapeutic response MR imaging is as accurate as CT but CT remains the imaging modality of choice because it is more widely available and quicker. This article reviews that evidence and outlines a place for the use of MR imaging in ovarian cancer.

Lymph node imaging: Basic principles

Lymph nodes are involved in a wide variety of diseases, particularly in cancer. In the latter, precise nodal staging is essential to guide therapeutic options and to determine prognosis. For long, imaging of the lymphatic system has been limited to lymph vessel,especially via the exclusive use of conventional lymphography, at the expense of invasive procedures and patient's discomfort. Three main technical advances, however, have recently completed the clinical armamentarium for lymph node imaging: first, the refinement of cross sectional imaging, i.e. CT and MRI, combined or not with dedicated contrast agents, has progressively replaced conventional lymphography in oncology situations; second, the development of intra-operative sentinel node mapping has profoundly modified the diagnostic and therapeutic procedures in several cancer situations, mostly melanoma and breast cancer; finally, the increased availability of functional imaging, especially through the use of FDG-PET, has greatly contributed to the accuracy improvement of nodal metastases identification. The aim of this review will thus be to briefly review the anatomy and physiology of the lymphatic systems and to overview the basic principles of up-to-date lymph node imaging.

Imaging the lymphatic system: possibilities and clinical applications

The lymphatic system is anatomically complex and difficult to image. Lymph ducts are responsible for the drainage of part of the body's interstitial fluid. Lymph nodes account for the enrichment of lymph fluid, and can be involved in a large variety of diseases, especially cancer. For a long time, lymphatic imaging was limited to the sole use of conventional lymphography involving invasive procedures and patient discomfort. New contrast agents and techniques in ultrasound, nuclear medicine, and MR imaging are now available for imaging of both the lymphatic vessels and the lymph nodes. The objective of this review is to discuss the different imaging modalities of the lymphatic system, with a special focus on the new possibilities of lymphatic imaging including enhanced MR lymphography, sentinel node and positron emission tomography imaging, and contrast-enhanced ultrasound.

Lymphography: An Old Technique Retains Its Usefulness

Conventional lymphography has long been the method of choice for imaging the lymphatic system. However, the number of lymphographic studies performed in oncology centers has declined markedly since the introduction of cross-sectional imaging techniques, especially computed tomography (CT). Therefore, levels of expertise in both performing lymphography and interpreting lymphograms are falling. The unique ability of lymphography to demonstrate derangements of the internal architecture of normal-sized lymph nodes can be valuable and makes it more accurate than CT in evaluation of some lymphomas (especially Hodgkin disease) and genitourinary malignancies. In fact, lymphography and CT are complementary rather than mutually exclusive techniques for the staging of some lymphomas and genitourinary malignancies. In addition, lymphography opacifies the lymphatic channels and therefore may be a valuable tool for detection of lymphatic fistulas or lymphatic leakage. Finally, lymphography helps guide subsequent therapy in patients with lymphomas, genitourinary malignancies, or disorders of lymphatic flow.

Computerised tomography in the staging of Hodgkin's disease and non-Hodgkin's lymphoma

The last 25 years have seen major changes in the imaging investigation and subsequent management of patients with Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL); accurate staging is vital for prognostication and treatment in both, and particularly in HD. The choice of imaging modality for staging depends on its accuracy, impact on clinical decision-making, and availability. Modern CT scanners fulfil most of the desired criteria. The advent of CT scanning, along with the development of ever more effective chemotherapeutic regimens, has resulted in the virtual demise of bipedal lymphangiography (LAG) as a staging tool in patients with lymphoma. It has rendered superfluous a battery of other tests that were in routine use. This contribution reviews the evidence for the use of CT in preference to LAG. CT accurately depicts nodal enlargement above and below the diaphragm, has variable sensitivity for intra-abdominal visceral involvement and is generally outstanding in depicting the extent of disease, especially extranodal extension. Despite the advances in CT technology, there are still areas where CT performs less well (e.g. disease in normal-sized lymph nodes, splenic and bone marrow infiltration). The influence of technical factors, such as the use of intravenous contrast medium, is discussed. In some instances, CT is not the imaging modality of choice and the place of newer techniques such as MRI and endoscopic ultrasound will be reviewed.

Pelvic lymphoscintigraphy: contribution to the preoperative staging of rectal cancer

PURPOSE

Preservation of the anal sphincter in surgery for cancer of the distal rectum in an attempt to avoid colostomy has been a main concern of colorectal surgeons. Various proposed procedures contradict oncological principles, especially with respect to pelvic lymphadenectomy. Therefore, prior knowledge of pelvic lymph node involvement is an important factor in choosing the operative technique, i.e., radical or conservative resection. Introduction of ultrasound, computerized tomography, and magnetic resonance have made preoperative study of the area possible. Nevertheless, these resources offer information of an anatomical nature only. Lymphoscintigraphy enables the morphological and functional evaluation of the pelvic area and contributes toward complementing the data obtained with the other imaging techniques. The objective of this prospective study is twofold: to standardize the lymphoscintigraphy technique and to use it to differentiate patients with rectal cancer from those with other coloproctologic diseases.

CASUISTIC AND METHODS

Sixty patients with various coloproctologic diseases were studied prospectively. Ages ranged from 21 to 96 years (average, 51 and median, 55 years). Twenty-six patients were male and 34 were female. Thirty patients had carcinoma of the distal rectum as diagnosed by proctologic and anatomic-pathologic examinations, 20 patients had hemorrhoids, 5 had chagasic megacolon, 2 had diverticular disease, 2 had neoplasm of the right colon, and 1 had ulcerative colitis as diagnosed by proctologic exam and/or enema. The lymphoscintigraphy method consisted of injecting 0.25 mL of a dextran solution marked with radioactive technetium-99m into the right and left sides of the perianal region and obtaining images with a gamma camera. The results were analyzed statistically with a confidence level of 95% (P <.05) using the following statistical techniques: arithmetic and medium average, Fisher exact test, chi-square test corrected for continuity according to Yates, and distribution tables for the number of patients.

RESULTS

In rectal cancer, the tracer progresses unilaterally or is absent; in other patients, the progress of the tracer is bilateral and symmetrical, although its progress may be slow. Statistical tests showed with high significance that the agreement index between the clinical diagnosis and the result of the lymphoscintigraphic exam was 93%.

CONCLUSIONS

Lymphoscintigraphy is a standardized, painless, and harmless test that can be performed in all cases; it differentiates patients with rectal cancer from those with other coloproctological diseases.

Is it wise to eliminate lymphography from the staging of Hodgkin's disease?

We believe that lymphography and CT are complementary rather than mutually exclusive techniques for the diagnosis and staging of HD. Unfortunately, it seems that many radiologists and clinicians disregard the ability of lymphography to provide qualitative information on lymph node architecture, which is not available by CT. The use of lymphography is declining in several teaching centers throughout the world. This makes it difficult for young radiologists to acquire the skills needed to perform and interpret lymphographies successfully. In turn, radiologists who have little experience with lymphography are less likely to use the technique. Because most of the treatment-related morbidity in HD is dose-related, and because lymphography helps to avoid over- and undertreatment, we believe that high-quality lymphography continues to have a significant role in the staging of selected HD patients. Moreover. lymphography may reduce both the cost of management and the morbidity rate in many HD patients. One solution would be to continue to use lymphography in a small number of institutions specialized in the management of HD.

The role of high resolution ultrasound with guided cytology of groin lymph nodes in the management of squamous cell carcinoma of the vulva: a pilot study

The accuracy of high resolution ultrasound with guided fine needle aspiration cytology in detecting inguinal lymph node involvement was assessed in 24 women undergoing radical vulvectomy and groin node dissection for squamous cell vulval cancer. Of the 43 groins dissected, ultrasound correctly diagnosed the lymph node status in 36, with five false positive and two false negative results. Cytology in 40 groins showed no false positive and five false negative results. The sensitivity and specificity for the combined techniques were 83% and 82% respectively. Assessed together, the combined technique failed to detect metastatic disease in two groins; in both cases the extent of nodal metastatic involvement was a solitary focus < 3 mm in diameter. The ultrasound and fine needle aspiration procedure is safe and well tolerated and can be repeated as needed for surveillance. The authors suggest that this procedure should be evaluated further to determine whether a policy of individual selection for lymphadenectomy can be implemented based on this technique.

Quantitative methods for indirect CT lymphography

In this investigation, we applied quantitative CT methods to characterize contrast enhanced lymph nodes opacified using iodinated contrast media for indirect CT lymphography. Iodinated nanoparticles were injected into the buccal submucosa and SQ into the metatarsus and metacarpus of four normal swine (1.0-4.0 ml/site, 76 mg I/ml). Attenuation (HU), volume (cm3), iodine concentration (mg I/cm3), total iodine uptake (mg I), contrast-to-noise ratio (CNR), and percent injected dose (%ID) were estimated in opacified inguinal, cervical and parotid/mandibular lymph nodes using manual image segmentation techniques on 24 hour post-contrast CT images. Lymph node volumes estimated by multiple slice ROI analysis were compared with estimates obtained by post-excisional weight measurements. HU and iodine concentration increased 5-20 fold in opacified nodes (p < 0.01) and CNR increased more than four-fold (p < 0.001). %ID ranged between 3.5 and 11.9% and did not appear dose related. ROI estimated lymph node volumes approximated volumes calculated from weight measurements. (R2 = 0.94, p < 0.0001). We conclude that interstitially injected iodinated nanoparticles increase attenuation and conspicuity of targeted nodes on CT images. Quantitative methods could play an important clinical role in more accurate metastasis detection.

Adjuvant radiation therapy for low stage testicular seminoma: Diagnosis and therapy in evolution

We performed a retrospective study to evaluate the clinical outcome of patients with early stage testicular seminoma who received adjuvant radiation therapy after orchiectomy over the past 15 years. During the 15 year period, 61 patients were treated with adjuvant radiation therapy for stages I, IIA, and IIB testicular seminoma. Patients received from 2,000 to 4,000 cGy delivered by a Cobalt machine and later by a linear accelerator. Our standard treatment protocol was modified in 13 patients: 7 secondary to abnormal lymphangiography (LAG) parameters and 6 due to abnormal computed tomography findings. We analyzed each patient's outcome for survival, recurrence, and complications. We then compared outcomes, looking for differing trends based on evolving evaluation or treatment techniques. The average follow-up is 75 months, with an overall survival rate of 93%. The cause specific survival is 100%. Four patients died from intercurrent diseases; at time of autopsy, one of these patients was noted to have a small focus of seminoma in a lateral inguinal node. He died from widely disseminated Hodgkin's disease. Three patients, including the aforementioned one, had recurrent disease outside of the radiation field, yielding a recurrence rate of 5%. No significant long term treatment complications were reported, although 24% of patients had one or more complications from LAG. Regardless the various changes in patient evaluation and radiation treatment techniques over the past 15 years, adjuvant radiation therapy remains effective in patients with early stage testicular seminoma.

Indirect computed tomography lymphography of subdiaphragmatic lymph nodes using iodinated nanoparticles in normal dogs

RATIONALE AND OBJECTIVES

We evaluated the imaging characteristics of an iodinated particulate contrast agent for indirect computed tomography (CT) lymphography of normal subdiaphragmatic lymph nodes in dogs.

METHODS

Four milliliters of a 15% (wt/vol) iodinated nanoparticle suspension was injected into the gastric, colonic, rectal, or cervical submucosa, loose paraprostatic fascia, or metatarsal subcutaneous tissues in 10 healthy beagles. Endoscopic, CT, or ultrasound guidance was used when necessary to facilitate contrast agent delivery. CT and radiographic images were obtained prior to contrast administration and at 4 hr, 24 hr, and 7 days postcontrast injection. Postmortem examinations were then conducted.

RESULTS

CT images showed enhancement of regional lymph nodes draining the various injection sites. The mean attenuation of opacified nodes was 678 +/- 463 Hounsfield units 24 hr after injection and remained elevated 7 days later. Lymph node opacification on CT images correlated well with the node location observed on postmortem examinations.

CONCLUSION

Subdiaphragmatic lymph nodes can be effectively opacified using an iodinated nanoparticle contrast agent for indirect CT lymphography.

Iodinated nanoparticles for indirect computed tomography lymphography of the craniocervical and thoracic lymph nodes in normal dogs

RATIONALE AND OBJECTIVES

We evaluated the imaging characteristics of an interstitially or intraperitoneally delivered iodinated particulate contrast agent for computed tomography (CT) lymphography of the craniocervical and thoracic lymph nodes.

METHODS

We injected 2-4 ml of 15% wt/vol iodinated nanoparticle suspension subcutaneously, submucosally, or intraperitoneally in eight normal dogs. CT and plain radiographic images were obtained prior to contrast administration and 4 hr, 24 hr, and 7 days after injection. Correlation was made to detailed postmortem assessment.

RESULTS

CT images showed enhancement of regional nodes draining injection sites. Mean attenuation of opacified nodes was 313 +/- 297 (mean +/- standard deviation), 536 +/- 453, and 492 +/- 372 Hounsfield units at 4 hr, 24 hr, and 7 days postinjection, respectively. Lymph node opacification on CT images correlated well with node location found at postmortem.

CONCLUSION

Craniocervical and thoracic lymph nodes can be effectively opacified from interstitial or intraperitoneal delivery of this iodinated nanoparticulate contrast agent.

Is there still a role for lymphography in the management of early stage carcinoma of the cervix?

The value of lymphography in the management of carcinoma of the cervix is controversial and in many institutions has ceased to be used as part of routine staging. We present the results of 103 patients with carcinoma of the cervix treated by radical radiotherapy alone at the Royal Marsden Hospital between 1984 and 1990 all of whom had a staging lymphogram and computed tomography (CT) of the abdomen and pelvis as part of their routine staging prior to therapy. Our results show that 72 patients (70%) had no involved nodes detected on either CT or lymphography (LG--ve/CT--ve) while 16 patients (15.5%) were thought to have involved lymph nodes on lymphography alone but not on CT (LG+ve/CT-ve). The remaining 15 cases (14.5%) had involved lymph nodes on both CT and lymphography (LG+ve/CT+ve). There were no patients shown to have involved lymph nodes on CT with a negative lymphogram. Survival analysis on these three groups showed that patients in the LG+ve/CT+ve group did worse than the other two groups with only a 28% 5 year survival compared with 60% (LG-ve/CT-ve group) and 64% (LG+ve/CT-ve group) (p < 0.1). This effect of lymph node involvement disappeared in a multivariate analysis using Cox regression when stage came out as the strongest factor affecting survival. After controlling for stage, a further analysis of patients with only stage I and II disease has shown that patients who were LG+ve/CT+ve still did significantly (p < 0.05) worse (30% 5 year survival) than the other two groups: LG-ve/CT-ve group altered clinical management in 5/6 patients with stage I or IIA disease who avoided radical surgery and who were given a parametrial boost to the site of lymph node involvement. The possible benefit of this additional treatment to explain the higher survival rate of patients in the LG+ve/CT-ve group is discussed further. We conclude that lymphography still has a limited role to play in patients with early stage disease (I or IIA) who do not appear to have involved lymph nodes on CT scanning.

Low-reflectivity periportal collar on hepatic ultrasound

A low attenuation periportal collar is frequently found on computed tomography (CT) in association with a variety of liver diseases and other conditions (Lawson, T L, Thorsen, M K, Erikson, S J et al, Periportal halo: a CT sign of liver disease, Abdom. Imaging, 18, 42-46 (1993)). Abnormal periportal intensity has been reported on magnetic resonance imaging (MRI) in various hepatobiliary diseases. Transient low reflectivity periportal cuffing has recently been described and was presumed to be due to periportal lymphoedema associated with malignant lymphadenopathy. We report the finding of such bands in four patients with chronic hepatobiliary disease and present the associated histological findings.

CT evaluation of lymph node status at presentation of prostatic carcinoma

Computed tomographic (CT) studies performed within a general oncology service in 104 consecutive patients with prostatic carcinoma were reviewed retrospectively to assess the incidence and distribution of lymphadenopathy. All patients were staged with CT at initial presentation, had normal skeletal scintigrams and were candidates for radical radiotherapy. The likelihood of lymphadenopathy was associated with increasing T-stage. 57 of the 92 (62%) patients without lymph node enlargement had local disease confined to the prostate (T2 or less) compared with only two of the 12 (17%) patients with enlarged nodes. Lymph node enlargement was more likely with a primary tumour of poorly differentiated histology. 12 patients (11.5%) had lymphadenopathy by established CT criteria; six with pelvic nodal enlargement alone and six with enlargement of pelvic and retroperitoneal nodes. In all patients pelvic nodal enlargement predominated and no patient had isolated retroperitoneal lymphadenopathy. Our findings indicate that CT staging studies of prostatic cancer do not need to include the retroperitoneum if there is no lymphadenopathy at or below the aortic bifurcation.