Retroperitoneal and pelvic lymph node imaging

Abstract

HE MAJORITY of malignant tumors have a high pro-T pensity for eventual metastastes to regional, and then to other, lymph node groups. Therefore, an evaluation of the lymph node groups at risk for tumor involvement is an integral part of the initial staging of a variety of malignant tumors, with consequent important impact upon treatment planning and prognosis. This assessment provides information for the N (lymph node) aspect of the commonly employed TNM tumor classification scheme and for other staging classifications.This review will focus on imaging techniques that are currently used to evaluate lymph nodes in the retroperitoneum and pelvis. These lymph nodes lie in close proximity to the major vessels of the retroperitoneum and pelvis because they share common embryologic origins. These include the nodes that lie adjacent to the abdominal aorta and inferior vena cava (known as the paraaortic and/or paracaval nodes) and the common iliac, external iliac, and internal iliac (or hypogastric) vessels, including the major branches of the latter trunk. Excluded from this discussion are those nodes that lie within the abdominal cavity and adjacent to the organs of the gastrointestinal tract, i.e., the mesenteric, peripancreatic, porta hepatic, and splenic hilar lymph node groups.An assessment of the retroperitoneal and pelvic lymph nodes is of importance for those solid tumors for which these lymph node groups are the primary site of lymphatic drainage and, therefore, are at highest risk for potential lymph node metastases, such as carcinomas of the genitourinary tract (prostate, testis, ovary, uterus, uterine cervix, kidney, ureter, and bladder). These nodes are also at high risk for involvement in patients with Hodgkin's disease and the non-Hodgkin's lymphomas; their assessment in these malignant disorders is reviewed elsewhere' and noted here for sake of completeness only. AnatomyThe lymphatic system is comprised of a series of lymph nodes connected by lymphatic channels, which, among other functions, serve to return interstitial fluid to the cardiovascular circulatory system. Although there is wide variation in the numbers and groupings of lymphatic channels and lymph nodes, there are clearly defined patterns of lymphatic drainage from various organs that allow prediction of which lymph node groups are at highest risk for the earliest manifestation of nodal metastases from primary organ sites.The lymphatics of the pelvis and retroperitoneum follow the direction of drainage of the accompanying venous system. At the upper retroperitoneum, the lymphatic fluid is conveyed via the thoracic duct into the jugular vein in the neck (explaining the occurrence of adenopathy at this site from metastases, the so-called Virchow node) and then into the pulmonary vascular bed (accounting for pulmonary metastases). Retroperitoneal lymphatics also anastomose with the lymphatic plexus in the thoracic paravertebral region, which drains the intercostal spaces in proximity to the major trunks of the azygos venous system (thus accounti...

Management of patients with an increasing prostate-specific antigen after radical prostatectomy

“…Magnetic resonance imaging (MRI) is thought to be comparable with CT in its ability to detect metastatic lymph nodes. Therefore, CT or MRI may be useful in the evaluation of a man with an increasing serum PSA and is being considered for salvage radiation therapy [35]. In addition, MRI also may be useful in evaluating for suspected bony metastases or spinal cord compression when other modalities are inconclusive [36].…”

What does prostate-specific antigen recurrence mean?

“…This would prevent the unwarranted use of salvage pelvic radiation therapy in these men, who would be better served by systemic therapy. Magnetic resonance imaging is believed to be comparable with CT in its ability to detect metastatic lymph nodes, and thus either CT or magnetic resonance imaging may be useful in evaluating men with suspected local recurrence who are being considered for salvage radiation therapy [29].…”