Advances in imaging of lymph flow disorders.

Conventional oil-contrast lymphography has long been the mainstay for lymphatic imaging. However, the emergence of computed tomography (CT) and magnetic resonance (MR) imaging has severely curtailed its use. Because of recent improvements and refinements, lymphangioscintigraphy now permits high-resolution imaging of peripheral lymphatic vessels and provides insight into lymph flow dynamics. It is indispensable for patients with known or suspected lymphatic circulatory disorders in confirming the diagnosis and delineating the pathogenesis and evolution of lymphedema. In addition, lymphangioscintigraphy helps evaluate lymphatic truncal anatomy and radiotracer transport. It can also be used to evaluate the efficacy of various treatment options designed to facilitate lymph flow or reduce lymph formation. The procedure is essentially noninvasive, can easily be repeated, and does not adversely affect the lymphatic vascular endothelium. MR imaging complements lymphangioscintigraphy in the monitoring and treatment of more complex lymphatic circulatory disorders, whereas CT facilitates catheter-guided percutaneous sclerosis or obliteration of specific lymphangiectasia or lymphangioma syndromes. Ultrasonography has proved useful in the setting of filariasis. Patients with a provisional diagnosis of peripheral lymphatic dysfunction or idiopathic edema should undergo diagnostic lymphangioscintigraphy and, in some cases, MR imaging to verify diagnostic accuracy, pinpoint the specific abnormality, and help guide subsequent therapy.

Radionuclide lymphangioscintigraphy in the evaluation of peripheral lymphedema.

PURPOSE: The primary difficulty in evaluating and treating peripheral lymphedema is visualization of the lymphatics. Functional lymphatic studies have been performed on patients with peripheral edema to diagnose lymphedema, to determine its severity, and to understand the varied drainage patterns. METHODS: After intradermal injection in the hands or feet, initial flow and whole-body images were taken using Tc-99m human serum albumin in more than 700 patients with possible lymphedema. RESULTS: Clear images of truncal lymph transport and draining lymph nodes were obtained, and pattern differences between primary and secondary lymphedema were seen. Follow-up studies showed any functional change in lymphatic dynamics. CONCLUSION: Peripheral lymphatics can now be easily visualized. Because lymphangioscintigraphy can be performed before and after medical treatment, follow-up evaluation of patients with lymphedema is possible. The procedure is noninvasive, repeatable, easy to perform, and harmless to the lymphatic endothelium.

Lymphatic abnormalities in human filariasis as depicted by lymphangioscintigraphy.

BACKGROUND: Investigation into filarial lymphedema has been hampered by the lack of a simple, safe, and easily repeated test to image the peripheral lymphatic system. Recent refinements in radionuclide lymphangioscintigraphy have established this noninvasive technique as the initial procedure of choice for visualizing lymphatics. Accordingly, we applied lymphangioscintigraphy to patients with filariasis and, for purposes of interpretation, compared the findings with those in patients with non-filarial lymphedema. METHODS: Thirty-three patients with classic symptoms or signs consistent with acute or chronic filariasis underwent lymphangioscintigraphy, and the findings were compared with those in five patients without lymphatic dysfunction and in 50 other patients with primary or secondary lymphedema without exposure to filariasis. RESULTS: As in patients with nonfilarial lymphedema, scintigraphic abnormalities in the 33 patients with filariasis included delayed or absent tracer transport of the radiotracer (25 patients), tortuous and bizarre deep lymphatics (seven patients), dermal diffusion (15 patients), retrograde tracer flow (six patients), and faint or absent regional nodal visualization (14 patients). Even in patients with long-standing filarial lymphedema, peripheral trunks were often visualized (at least in part), and regional nodes and more central lymphatics sometimes filled after light exercise. In some of the latter patients, however, discrete lymphatic trunks were not detected. CONCLUSION: Lymphangioscintigraphy is a simple, safe, reliable, noninvasive method with which to examine the peripheral lymphatic system, including truncal and nodal abnormalities, in endemic populations with occult and overt lymphatic filariasis.

Effects of intravenous and aerosolized arachidonic acid on alveolar epithelial permeability in rabbits.

To determine whether arachidonic acid (AA) alters alveolar epithelial permeability, we studied the effect of both continuous intravenous and aerosolized AA on clearance of [99m]Tc-DTPA from lung to blood in rabbits. Although intravenous AA increased prostacyclin production and aerosolized AA decreased systemic blood pressure, neither continuous intravenous nor aerosolized AA augmented alveolar epithelial permeability.

Lymphangioscintigraphy in AIDS-associated Kaposi sarcoma.

Kaposi sarcoma, a common opportunistic neoplasm complicating AIDS, is thought to arise from the vasculature and possibly from lymphatic endothelium. To evaluate the nature and extent of lymphatic involvement in AIDS-associated Kaposi sarcoma, we used an improved technique of whole-body lymphangioscintigraphy. Six human-immunodeficiency-virus-seropositive men (40-51 years old) with AIDS and extensive Kaposi sarcoma had bilateral foot and/or hand intradermal injection of 0.05 ml of 99mTc-labeled human serum albumin (500 microCi, 18.5 MBq). After sequential whole-body scanning with a digital gamma camera, the findings were interpreted by comparing them with findings from similar studies in 30 other patients without AIDS or Kaposi sarcoma (26 with primary or secondary lymphedema and four with normal extremities). Unlike in normal limbs, where lymphangioscintigraphy displayed early lymphatic truncal and regional nodal filling with radionuclide, in patients with Kaposi sarcoma, lymphangioscintigraphy disclosed a variety of abnormal patterns with some features distinct and others resembling lymphatic dysplasia as seen in primary and secondary lymphedema. These included focal accumulation of tracer within lymphatic channels in the distribution of cutaneous Kaposi lesions; delayed tracer transport with absent, faint, or intense regional lymph nodal uptake; and retarded or impeded lymphatic drainage with tracer intensification in the region of Kaposi sarcoma plaques. The impaired lymphatic drainage and nodal dysfunction seen on scintigrams in patients with AIDS-associated Kaposi sarcoma suggest a close connection between the lymphatic system and this disorder.

Whole-body lymphangioscintigraphy: preferred method for initial assessment of the peripheral lymphatic system.

In 20 patients with congenital and acquired lymphedema in either upper or lower extremities and in four patients without extremity edema, human serum albumin labeled with technetium-99m was injected intradermally into a digital web space of the hand or foot. With a digital gamma camera that permitted a "sweep" of the torso, serial extremity and whole-body lymphagioscintigraphy (LAS) of the peripheral lymphatic system was performed. In 11 patients with acquired lymphedema, a well-defined obstructive pattern was seen, characterized by discrete peripheral lymphatic trunks, delayed or absent depiction of regional nodes, and delayed but extensive soft-tissue tracer extravasation. Five of nine patients with congenital lymphedema showed hypoplasia characterized by poorly defined lymphatic trunks, delayed depiction of regional nodes, and early and extensive extravasation of tracer. The other four patients showed aplasia, with absence of trunks, no depiction of nodes, and little or no tracer extravasation. LAS is technically simple to perform and requires no special training. Radiation exposure is minuscule, and the procedure is safe and without apparent side effects. For these reasons, whole-body LAS should be the preferred method for the initial assessment of congenital or acquired lymphedema.

Massive lymphocele following pelvic lymphadenectomy for staging of prostatic cancer.

Two patients developed massive pelvic lymphoceles within 30 days of retroperitoneal node dissection for staging of prostatic cancer. Excised lymph nodes were negative for metastases. Both patients developed severe bilateral peripheral edema, and one developed pulmonary thromboembolism from intraluminal thrombi in the adjacent, compressed inferior vena cava. Each patient responded to unroofing of the cyst wall with either concomitant external or internal drainage.

Splenic salvage quantified by uptake of heat-damaged radiolabeled red blood cells. Experimental and clinical studies.

We evaluated a noninvasive radionuclide technique to quantify splenic trapping function, which is a key step in the disposition of blood-borne particulates such as poorly opsonized encapsulated microorganisms implicated in hyposplenic fulminant sepsis. Using computerized external gamma imaging, the percentage of splenic uptake of heat-damaged radiolabeled red blood cells was determined in adult Sprague-Dawley rats with eutopic (partial splenectomy) or ectopic (single or multiple autotransplantation) remnants or whole spleens, and in 14 patients with either an intact spleen or splenic remnants after treatment for trauma or hypersplenism. The masses of both eutopic and ectopic remnants correlated directly with the percentage of heat-damaged red blood cell uptake, but the percentage of uptake per gram was higher in eutopic remnants, paralleling more vigorous compensatory growth. In patients, the percentage of heat-damaged red blood cell uptake by remnant spleens was similar to that seen in the rats and, in addition, was supernormal in those with congestive splenomegaly. This noninvasive technique both provides a vivid biplanar image and quantifies blood-borne particle trapping, which is a key splenic function. A heat-damaged red blood cell uptake of less than 15 percent after splenic salvage suggests marginal splenic performance and continued vulnerability to overwhelming sepsis.

Characteristics of the transplanted heart in the radionuclide ventriculogram.

We examined conventional radionuclide ventriculograms of 19 heart transplant patients and 12 control patients. R-to-R intervals were shorter in heart transplant patients (630 +/- 95 msec) than in controls (781 +/- 204 msec, p less than 0.01). The elevated heart rate is associated with a decreased left ventricular ejection fraction (56.7 +/- 10.3% vs 67.4 +/- 6.1%, p less than 0.005) and decreased emptying time (225 +/- 21 msec vs 270 +/- 47 msec, p less than 0.01), a shorter interval from the R wave to end systole (311 +/- 28 msec for heart transplant patients vs 349 +/- 48 msec in controls, p less than 0.01) and decreased filling time (262 +/- 61 msec vs 340 +/- 123 msec, p less than 0.01). The maximal filling rate is significantly increased (4.3 +/- 1.4 end diastolic volume/sec in heart transplant patients) compared with controls (3.0 +/- 1.1 end diastolic volume/sec, p less than 0.01, Student's t test). In those patients for whom the interval between the transplant procedure and the radionuclide ventriculogram study was greater than 360 days, the filling time (231 +/- 34 vs 296 +/- 67 msec) and emptying time (216 +/- 18 vs 235 +/- 20 msec, p less than 0.05) were significantly less than for those transplants in place less than 1 year. Other parameters were not significantly different. Those heart transplant patients having had two or more documented rejection episodes had no significant difference in hemodynamic function when compared with patients with one or no rejection episodes; no measure of the severity of rejection was used in this analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Ferrokinetic and hematologic studies in cystic fibrosis patients.

We investigated 28 cystic fibrosis (CF) patients to determine why hypoxia from their obstructive pulmonary disease does not produce polycythemia. Oxygen saturation was lower and erythropoietin levels were higher in CF patients than in 25 age-comparable reference subjects (90.8% and 47 mimu vs. 94.7% and 29 mimu, p less than 0.01). Hematocrit and red blood cell (RBC) indices were not different between groups. Serum vitamin and iron levels, ferrokinetics, RBC volume, and RBC survival were studied in 10 of the 28 CF patients. Total iron-binding capacity and vitamin E levels were low, and serum iron, ferritin, vitamin B12, and folate levels were normal in these patients. Red blood cell survival was minimally decreased in six patients although there was no other evidence for hemolysis. Ferrokinetics (59Fe) indicated a reduction in total erythropoiesis in only two patients. Plasma volume was high-normal in five and above normal in four CF patients; RBC mass was increased appropriately for each patient's degree of hypoxia, when compared to healthy individuals living at different altitudes. These results suggest that CF patients are able to compensate for hypoxia by increasing RBC mass; however, an expanded plasma volume prevents a detectable rise in hematocrit.