Side-to-side symmetry of radioprotein transfer from tissue space to systemic vasculature following subcutaneous injection in normal subjects and patients with breast cancer

Lymphatic uptake of biotherapeutics through a 3D hybrid discrete-continuum vessel network in the skin tissue

Subcutaneous administration is a common approach for the delivery of biotherapeutics, which is achieved mainly through the absorption across lymphatic vessels. In this paper, the drug transport and lymphatic uptake through a three-dimensional hybrid discrete-continuum vessel network in the skin tissue are investigated through high-fidelity numerical simulations. We find that the local lymphatic uptake through the explicit vessels significantly affects macroscopic drug absorption. The diffusion of drug solute through the explicit vessel network affects the lymphatic uptake after the injection. This effect, however, cannot be captured using previously developed continuum models. The lymphatic uptake is dominated by the convection due to lymphatic drainage driven by the pressure difference, which is rarely studied in experiments and simulations. Furthermore, the effects of injection volume and depth on the lymphatic uptake are investigated in a multi-layered domain. We find that the injection volume significantly affects the rate of lymphatic uptake through the heterogeneous vessel network, while the injection depth has little influence, which is consistent with the experimental results. At last, the binding and metabolism of drug molecules are studied to bridge the simulations to the drug clearance experients. We provide a new approach to study the diffusion and convection of drug molecules into the lymphatic system through the hybrid vessel network.

Tc-99m-Human Serum Albumin Transit Time as a Measure of Arm Breast Cancer-Related Lymphedema

BACKGROUND

Lymphoscintigraphy has often been used for evaluating arm lymphatic dysfunction, but no optimal approach for quantification has so far emerged. We propose a quantifiable measure of lymphatic function that we applied in patients treated for breast cancer.

METHODS

Eleven patients, aged 34-68 years, with unilateral arm lymphedema following breast cancer treatment underwent bilateral lymphoscintigraphy using intradermal injection in both hands of technetium-99m-labeled human serum albumin and sequential 5 min imaging for 5 hours. The mean transit time (MTT) in the arms was calculated based on time activity curves generated from injection site and arm regions. Visual lymphedema scoring was performed based on dermal backflow and lymph node presence. Excess arm volume was calculated from circumference measurements.

RESULTS

The MTT (mean ± SD) was significantly longer in the lymphedema arm than in the normal arm: 60.1 ± 27.7 versus 5.4 ± 2.5 minutes (mean difference, 54.7 minutes; 95% confidence interval, 36.5-72.9 minutes; P < 0.0001). Patients with previous erysipelas infection had significantly longer MTT than other patients (mean difference, 43.7 minutes; 95% confidence interval, 18.6-68.7 minutes; P < 0.001). There was a positive correlation between MTT and excess arm volume (r = 0.64; P = 0.04) and number of lymph nodes removed (r = 0.65; P = 0.03) but no correlation between visual score and MTT.

CONCLUSION

Measurements of MTT were able to discriminate lymphedema from healthy arm and MTT correlated with relevant markers for lymphedema severity. We encourage further research using the MTT approach for monitoring lymphedema and evaluation of treatment response.

Validity of Quantitative Lymphoscintigraphy as a Lymphedema Assessment Tool for Patients With Breast Cancer

Objective

To evaluate the validity of quantitative lymphoscintigraphy as a useful lymphedema assessment tool for patients with breast cancer surgery including axillary lymph node dissection (ALND).

Methods

We recruited 72 patients with lymphedema after breast cancer surgery that included ALND. Circumferences in their upper limbs were measured in five areas: 15 cm proximal to the lateral epicondyle (LE), the elbow, 10 cm distal to the LE, the wrist, and the metacarpophalangeal joint. Then, maximal circumference difference (MCD) was calculated by subtracting the unaffected side from the affected side. Quantitative asymmetry indices (QAI) were defined as the radiopharmaceutical uptake ratios of the affected side to the unaffected side. Patients were divided into 3 groups by qualitative lymphoscintigraphic patterns: normal, decreased function, and obstruction.

Results

The MCD was highest in the qualitative obstruction (2.76±2.48) pattern with significant differences from the normal (0.69±0.78) and decreased function (1.65±1.17) patterns. The QAIs of the axillary LNs showed significant differences among the normal (0.82±0.29), decreased function (0.42±0.41), and obstruction (0.18±0.16) patterns. As the QAI of the axillary LN increased, the MCD decreased. The QAIs of the upper limbs were significantly higher in the obstruction (3.12±3.07) pattern compared with the normal (1.15±0.10) and decreased function (0.79±0.30) patterns.

Conclusion

Quantitative lymphoscintigraphic analysis is well correlated with both commonly used qualitative lymphoscintigraphic analysis and circumference differences in the upper limbs of patients with breast cancer surgery with ALND. Quantitative lymphoscintigraphy may be a good alternative assessment tool for diagnosing lymphedema after breast cancer surgery with ALND.

Reproducibility of lymphoscintigraphic evaluation of the upper limb

BACKGROUND

Although reproducibility studies are missing, a lymphoscintigraphic evaluation of the upper limb is often used in routine practice to diagnose lymphedema and in clinical research, for example, to investigate the effect of a physical treatment. Therefore, the aim of the present study was to investigate the reproducibility of the lymphoscintigraphic evaluation of the upper limb.

METHODS AND RESULTS

In breast cancer patients, 20 lymphoscintigraphic evaluations of the upper limb were performed on two test occasions with an interval of 1 week. (99m)Tc nanocol was injected subcutaneously in the hand. A standardized protocol was applied. In the early phase, two static images of the injection places were taken and in between dynamic images of both axilla during 40 min (15 min rest, 15 min squeezing a ball, and 15 min rest). After a break of 70 min, a static image of the injection places and of the axilla was made. At the end, a partial whole body image was acquired. A strong reproducibility was found for the following quantitative variables (ICC 0.75 to 0.85): change of uptake in axilla during the break; change of extraction from hands during the break; and extraction and uptake in the late phase. The other quantitative variables (i.e., extraction form the hands in the early phase, time of arrival, accumulation rate, and uptake in axilla in the early phase) had weak to moderatie reproducibility (ICC 0.07 to 0.70). All qualitative variables (i.e., number of lymph nodes in the axilla, upper arm and elbow/lower arm, gradation of lymph collectors in upper or lower arm and of dermal backflow, and presence of lymph collaterals) had strong to very strong reproducibility (ICC 0.76 to 1.00).

CONCLUSION

A lymphoscintigraphy of the upper limb is a reproducible imaging tool to assess lymph transport quantitatively and qualitatively.

A quantitative examination of lymph drainage from perilesion skin in human melanoma

BACKGROUND

An increase in lymph flow from melanomas to draining lymph nodes has been reported in animal studies. It has been postulated that this contributes to metastatic potential of cancers. Data from animal studies are not easily extrapolated to humans; animal studies use immunosuppressed animals modified to overexpress lymphangiogenic growth factors, injected with human tumor cell lines, or manipulated to develop aggressive tumors. Human studies are required to investigate lymph flow in humans with cancers such as melanoma.

METHODS AND RESULTS

The present study aims to quantify the removal rate constant k (a measure of local lymph flow per unit volume of distribution of the radiotracer) from the vicinity of melanomas, benign nevi, and normal skin in humans in vivo using quantitative lymphoscintigraphy (QL). 16 patients with pigmented lesions underwent QL to quantify k near the lesion (k(perilesion)) and in contralateral matched normal skin (k(control)). The lesions were then excised and, based on histological outcome, the patients were divided into two groups: benign nevus (n=9) and melanoma (n=7). There was no difference between k(perilesion) and k(control) in either the benign naevus (p=0.29, paired t test) or the melanoma group (p=0.93). k(perilesion) in melanomas (0.233±0.123% min(-1)) was not increased relative to k(perilesion) in benign nevi (0.376±0.231% min(-1), p=0.16, unpaired t test).

CONCLUSIONS

We found no evidence for increased lymphatic drainage in melanoma relative to benign nevi or normal matched skin in humans.

Dermal clearance model for epidermal bioavailability calculations

A computational model for estimating dermal clearance in humans of arbitrary, nonmetabolized solutes is presented. The blood capillary component employs slit theory with contributions from both small (10 nm) and large (50 nm) slits. The lymphatic component is derived from previously reported clearance measurements of dermal and subcutaneous injections of (131)I-albumin in humans. Model parameters were fitted to both blood capillary permeability data and lymphatic clearance data. Small molecules are cleared largely by the blood and large molecules by the lymph. The combined model shows a crossover behavior at approximately 29 kDa, in acceptable agreement with the reported value of 16 kDa. When combined with existing models for stratum corneum permeability and appropriate measures of tissue binding, the developed model has the potential to significantly improve tissue concentration estimates for large or highly protein-bound permeants following dermal exposure.

Minimally invasive quantification of lymph flow in mice and rats by imaging depot clearance of near-infrared albumin

There is a lack of available methods to noninvasively quantify lymphatic function in small experimental animals, a necessity for studies on lymphatic system pathophysiology. We present a new method to quantify lymph flow in mice and rats, based on optically monitoring the depot clearance of near-infrared fluorescently labeled albumin and subsequent calculation of removal rate constants (k). BSA was conjugated with Alexa680 NHS ester and remained stable in protein-rich solutions without free dye dissociation. To assess lymph flow, mice or rats were imaged every 30 or 60 min during a 3- to 6-h period following an intradermal injection of 0.5 or 1 μl Alexa680-albumin. Mice were awake between measurements, whereas rats were anesthetized throughout the experiment. The k, a parameter defined as equivalent to lymph flow, was calculated from the slopes of the resultant log-linear washout curves and averaged -0.40 ± 0.03 and -0.30 ± 0.02%/min for control C57BL/6 and C3H mice, respectively. Local administration of the vasoconstrictor endothelin-1 in mice led to a significant reduction in k, whereas overhydration in rats increased k, reflecting the coupling between capillary filtration and lymph flow. Furthermore, k was 50% of wild type in lymphedema Chy mice where dermal lymphatics are absent. We conclude that lymph flow can be determined as its rate constant k by optical imaging of depot clearance of submicroliter amounts of Alexa680-albumin. The method offers a minimally invasive, reproducible, and simple alternative to assess lymphatic function in mice and rats.

Comparison of efficacy of Tc-99m HIG and Tc-99m nanocolloid on sentinel lymph node mapping in patients with breast cancer

BACKGROUND AND AIM

This study compared the effectiveness of Tc-99m human polyclonal immunoglobulin (HIG) and Tc-99m nanocolloid at detecting sentinel lymph nodes (SLNs) with lymphoscintigraphy and an intraoperative gamma-probe (IGP) in patients with early breast cancer.

METHODS

The study group consisted of 50 women; 25 patients each were given Tc-99m HIG or Tc-99m nanocolloid for lymphoscintigraphy. Then, intraoperative SLN localization with IGP was performed. The results of IGP, lymphoscintigraphy, blue dye injected just before surgery, and pathology were compared.

RESULTS

In the Tc-99m HIG group, one patient had tumours in both breasts. In two patients, we could not detect SLNs with lymphoscintigraphy, although they were detected with IGP and blue dye. We found SLNs for all tumours with IGP. With the intraoperative blue dye, SLNs were identified for 25 tumours; for one tumour, no SLN was detected with blue dye. In the histopathological examination, 13 tumours showed metastasis in the SLN and in 11 of these 13, there were also metastases in the axilla. One patient had a skip metastasis. In the Tc-99m nanocolloid group, SLNs were identified in 24 patients with lymphoscintigraphy. IGP found SLNs in 24 patients. The blue dye detected SLNs in all patients. On histopathological examination, 10 patients had metastasis in the SLN and there were also metastases in the axilla in all of these patients.

CONCLUSION

Tc-99m HIG can be used in SLN detection with preoperative lymphoscintigraphy and IGP in early-stage breast cancer patients.

Development of 68Ga-labeled mannosylated human serum albumin (MSA) as a lymph node imaging agent for positron emission tomography

INTRODUCTION

Although many sentinel lymph node (SLN) imaging agents labeled with (99m)Tc have been developed, no positron-emitting agent has been specifically designed for SLN imaging. Furthermore, the development of the beta probe and the requirement for better image resolution have increased the need for a positron-emitting SLN imaging agent. Here, we describe the development of a novel positron-emitting SLN imaging agent labeled with (68)Ga.

METHODS

A mannosylated human serum albumin (MSA) was synthesized by conjugating α-d-mannopyranosylphenyl isothiocyanate to human serum albumin in sodium carbonate buffer (pH 9.5), and then 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid was conjugated to synthesize NOTA-MSA. Numbers of mannose and NOTA units conjugated in NOTA-MSA were determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. NOTA-MSA was labeled with (68)Ga at room temperature. The stability of (68)Ga-NOTA-MSA was checked in labeling medium at room temperature and in human serum at 37°C. Biodistribution in normal ICR mice was investigated after tail vein injection, and micro-positron emission tomography (PET) images were obtained after injecting (68)Ga-NOTA-MSA into a tail vein or a footpad.

RESULTS

The numbers of conjugated α-d-mannopyranosylphenyl isothiocyanate and 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid units in NOTA-MSA were 10.6 and 6.6, respectively. The labeling efficiency of (68)Ga-NOTA-MSA was greater than 99% at room temperature, and its stability was greater than 99% at 4 h. Biodistribution and micro-PET studies of (68)Ga-NOTA-MSA showed high liver and spleen uptakes after intravenous injection. (68)Ga-NOTA-MSA injected into a footpad rapidly migrated to the lymph node.

CONCLUSIONS

(68)Ga-NOTA-MSA was successfully developed as a novel SLN imaging agent for PET. NOTA-MSA is easily labeled at high efficiency, and subcutaneously administered (68)Ga-NOTA-MSA was found to migrate rapidly to the lymph node.

Axillary lymph node drainage pathways from intradermal and intraparenchymal breast planes

BACKGROUND

To compare functional anatomy of breast peri-areolar and peri-tumoral lymphatic drainage basins.

METHODS

Fifteen breast cancer patients received simultaneous peri-areolar (intradermal) and peri-tumoral (intraparenchymal) injections of human polyclonal immunoglobulin (HIG) labeled with (99m)Tc and (111)In 2 to 4 h before axillary lymph node clearance surgery. Resected nodes (range 5-20; median 16) were individually counted for (99m)Tc and (111)In in a well-counter and ranked according to activity content (echelon). Activity in distal nodes was negligible so extraction efficiency (E) of HIG in the first echelon node was calculated as counts divided by total counts in the chain.

RESULTS

Five- to 10-fold more activity was recovered after intradermal injection. The injection planes identified the same first echelon node in 10 patients (group 1) but different in five (group 2). In group 1, intradermal E correlated with intra-parenchymal E (r = 0.82; P < 0.01). E of intradermal first echelon nodes in group 2 was 51 (SD 13)%, similar to intradermal E in group 1 (58 [23]%). E of intraparenchymal first echelon nodes in group 2, however, was 28 (6)%, lower than intraparenchymal E in group 1 (54 [20]%; P < 0.02).

CONCLUSIONS

Lymph nodes extract approximately 50% of HIG. Extracted HIG does not cascade to distal nodes, validating HIG for sentinel node lymphoscintigraphy. HIG injected intradermally at the areola drains via a single route to the axilla. In two-thirds of patients, peri-tumoral HIG follows a similar route, but in one-third of patients drainage from the parenchymal plane is more complex, with more than one route to the axilla.

Delivery of radiolabelled blood cells to lymphatic vessels by intradermal injection: a means of investigating lymphovenous communications in the upper limb

OBJECTIVE

To identify peripheral lymphovenous communications (LVCs) using labelled erythrocytes and intradermal injection. Intradermal injection delivers macromolecules to loco-regional lymph nodes faster than subcutaneous injection, suggesting easier lymphatic vessel access.

METHODS

Autologous erythrocytes labelled with 111In and 99mTc were injected into opposite hands. In four normal volunteers, the differentially labelled cells were given by intradermal injection on one side and subcutaneous injection on the other while in four breast cancer patients they were given by intradermal injection bilaterally 3 months after axillary lymph node clearance surgery. The axillae were imaged and blood samples obtained bilaterally at approximately 15, 30, 60, 120 and 180 min post-injection. Plasma activity was subtracted from whole blood activity to obtain erythrocyte-bound activity and contralateral concentrations were subtracted from ipsilateral concentrations to correct for ipsilateral recirculation. From estimated blood volume, erythrocyte and plasma activities contralateral to the injected side were calculated as percentage administered activity. Tracer concentrations in ipsilateral samples (%/l) were integrated to give total percentage administered activity, assuming a forearm blood flow of 20 ml/min.

RESULTS

Kinetics of plasma activity were consistent with small diffusible 99mTc complexes and protein-bound 111In. With both radionuclides, axillary nodes were visualized after intradermal but not subcutaneous injection, suggesting that nodal activity arises from erythrocytes. In one patient, 99mTc and 111In labelled erythrocytes accumulated in similar amounts ipsilaterally and contralaterally, suggesting bilateral LVCs distal to the ipsilateral sampling point. There was no evidence of LVCs in the other seven volunteers.

CONCLUSION

Intradermally injected erythrocytes are able to detect and potentially quantify peripheral LVCs.

Lymphatic drainage pathways of the breast and the upper limb

OBJECTIVE

To determine how often the sentinel lymph node (SLN) draining the breast is the same node as the SLN draining the upper limb. A common SLN might increase the risk of upper limb breast cancer-related lymphoedema after SLN biopsy.

METHODS

Patients with invasive breast cancer, identified as being suitable for axillary lymph node dissection, were injected preoperatively with 40 MBq of technetium-99m (Tc)-human polyclonal immunoglobulin G intradermally into the ipsilateral breast and 3 MBq of indium-111 (In)-human polyclonal immunoglobulin G intradermally into the ipsilateral hand, or vice versa. Axillary lymph nodes were removed, separated and assayed in a well counter for Tc and In.

RESULTS

Fifteen patients entered the study. In 13 of 15 patients, the 'hottest' lymph node for Tc was separate from the 'hottest' lymph node for In. In two of 15 patients the 'hottest' lymph node for Tc was also the 'hottest' lymph node for In, suggesting a common drainage pathway from the ipsilateral breast and upper limb.

CONCLUSION

Although the majority of patients has different pathways of lymphatic drainage from the ipsilateral breast and upper limb, in a small minority of patients the drainage pathway is through a common SLN. Such patients may be at increased risk of developing upper limb breast cancer-related lymphoedema after SLN biopsy.

Dual-isotope lymphoscintigraphy using albumin nanocolloid differentially labeled with 111In and 99mTc

The aim of this study was to develop and evaluate 111In- and 99mTc-labeled derivatives of albumin nanocolloid (NC) for dual-label lymphoscintigraphy to allow simultaneous comparison of lymphatic flow from different tissue planes draining a tumour bed for accurate identification of sentinel lymph nodes (SLN). Using the chelator, p-isothiocyanatobenzyl-1,4,7, 10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 111In-DOTA-NC and 99mTc-DOTA-NC were compared in vitro with respect to stability of labeling, colloidal status and particle size, then in vivo by measuring their clearance rates from a subcutaneous injection depot. 111In-DOTA-NC and 99mTc-DOTA-NC were indistinguishable on the basis of in vitro criteria. Their in vivo clearance rates, however, were disparate (0.0015 to 0.075 min(-1) for 111In and 0.0072 to 0.067 min(-1) for 99mTc), 111In being faster in three studies and markedly slower in three. This demonstrates that even when dual-labeled radiotracers behave identically in vitro, they will not necessarily do so in vivo. Further work is needed to develop dual-labeled NC.

Scintigraphic investigations of the superficial lymphatic system: quantitative differences between intradermal and subcutaneous injections

RATIONALE AND OBJECTIVES

Both subcutaneous and intradermal injections are used for the scintigraphic investigations of the superficial lymphatic system. The qualitative differences between these types of injections are well known. This study quantified their differences in a group of volunteers.

METHODS

With the limbs at rest, activities in the axillary nodes (AxN) were recorded at 1, 20, 40, 60, 80 and 100 min after subcutaneous or intradermal injection of TC-labelled human serum albumin nanocolloids in the ventral middle part of each forearm of nine young, healthy, male volunteers and the results were compared.

RESULTS

Expressed as per 10,000 of injected activity, activities recorded in the AxN were significantly higher (32.5 times as a mean value, ranging from 8.4 to 130.7 times) after intradermal injections than after subcutaneous injections (P<0.001 by using two-tailed Wilcoxon's signed-rank test). The mean AxN activity after intradermal injections was also apparently higher for the right limbs than for the left limbs, but when the paired t-test was used to compare the right with the left values of the nine volunteers, the comparison did not reach statistical significance (at T+100, 2P=0.087). When their handedness is taken into account, however, a level of statistical significance is reached (at T+100, 2P=0.025).

CONCLUSION

This study quantifies the differences between subcutaneous and intradermal injections, but also shows, although on a limited number of volunteers, that handedness influences the results of the intradermal injections.

Is there enhanced lymphatic function in upper body trained females?

BACKGROUND

Chronic physical activity results in adaptations in many aspects of human physiology, while specific training can directly influence structural changes. It remains unknown if habitual exercise influences upper extremity lymphatic function in females; thus, the purpose of this cross-sectional study was to compare different exercise stresses on lymphatic function in ten upper body trained females with ten untrained females.

METHODS AND RESULTS

Participants underwent a maximal upper body aerobic test on an arm crank ergometer before undergoing three randomly assigned lymphatic stress tests. Lymphoscintigraphy was used to quantify lymphatic function. (99m)Tc-antimony colloid was injected into the third web space of each hand, followed by 1 min spot views taken with a gamma-radiation camera. The maximal stress test required individuals to repeat their initial maximal exercise test. The subjects were then imaged every 10 min until 60 min were reached. The submaximal stress test involved arm cranking for 2.5 min at 0.6 W x kg(-1), followed by 2.5 min of rest, repeated for 60 min. The final stress test was a 60 min seated resting session. The clearance rate (CR) and axillary uptake (AX) were determined. Only AX post maximal exercise was significantly different between trained and untrained, p=0.009. All other measures of lymphatic function between groups were similar.

CONCLUSION

This study demonstrates no significant difference in lymphatic function between upper body trained and untrained females.

Upper extremity lymphatic function at rest and during exercise in breast cancer survivors with and without lymphedema compared with healthy controls

Lymphoscintigraphy was used to measure lymphatic function at rest and during exercise in breast cancer survivors with lymphedema (BCRL, n = 10), breast cancer survivors (BC, n = 10), and controls (Cont, n = 10). After injection of 99mTc-antimony colloid to the hands, subjects rested or performed 12 repeated sets of arm cranking for 2.5 min at 0.6 W/kg followed by 2.5 min of rest. One-minute spot views were taken with a gamma-radiation camera immediately postinjection and every 10 min over 60 min to calculate clearance rate. As well, an upper body scan was taken at 65 min postinjection to measure radiopharmaceutical uptake in the axilla (Ax) and forearm (Fore). All groups displayed similar increases in clearance rate with exercise ( P = 0.000). Ax significantly increased with exercise in Cont only [Cont: (mean ± SD) 4.9 ± 2.6 vs. 7.9 ± 4.2%, P = 0.000; BCRL: 1.4 ± 1.2 vs. 1.7 ± 2.1%, P = 0.531; BC: 3.9 ± 3.4 vs. 5.2 ± 3.2%, P = 0.130], whereas Fore, indicating dermal backflow, significantly increased in BCRL only (BCRL: 2.4 ± 0.87 vs. 4.4 ± 2.0%, P = 0.004; BC: 1.1 ± 0.25 vs. 1.1 ± 0.31%, P = 0.784; Cont: 0.93 ± 0.26 vs. 1.0 ± 0.20%, P = 0.296). The results indicate that, in women with BCRL, exercise causes radiopharmaceuticals to clear from the hand at the same rate as BC and Cont, but, instead of reaching the axilla, a greater amount of activity gets trapped in the dermis of the forearm. BC, meanwhile, have similar lymphatic function as Cont; however, there is a highly variable response that may suggest that some BC subjects may be at risk for developing lymphedema.

Human lymphatic pumping measured in healthy and lymphoedematous arms by lymphatic congestion lymphoscintigraphy

Axillary surgery for breast cancer partially obstructs lymph outflow from the arm, chronically raising the lymphatic smooth muscle afterload. This may lead to pump failure, as in hypertensive cardiac failure, and could explain features of breast cancer treatment-related lymphoedema (BCRL) such as its delayed onset. A new method was developed to measure human lymphatic contractility non-invasively and test the hypothesis of contractile impairment. 99mTc-human IgG (Tc-HIG), injected into the hand dermis, drained into the arm lymphatic system which was imaged using a gamma-camera. Lymph transit time from hand to axilla, ttransit, was 9.6+/-7.2 min (mean+/-s.d.) (velocity 8.9 cm min(-1)) in seven normal subjects. To assess lymphatic contractility, a sphygmomanometer cuff around the upper arm was inflated to 60 mmHg (Pcuff) before 99mTc-HIG injection and maintained for>>ttransit. When Pcuff exceeded the maximum pressure generated by the lymphatic pump (Ppump), radiolabelled lymph was held up at the distal cuff border. Pcuff was then lowered in 10 mmHg steps until 99mTc-HIG began to flow under the cuff to the axilla, indicating Ppump>or=Pcuff. In 16 normal subjects Ppump was 39+/-14 mmHg. Ppump was 38% lower in 16 women with BCRL, namely 24+/-19 mmHg (P=0.014, Student's unpaired t test), and correlated negatively with the degree of swelling (12-56%). Blood radiolabel accumulation proved an unreliable measure of lymphatic pump function. Lymphatic congestion lymphoscintigraphy thus provided a quantitative measure of human lymphatic contractility without surgical cut-down, and the results supported the hypothesis of lymphatic pump failure in BCRL.

Lymphoscintigraphy to Evaluate the Effect of High versus Low Intensity Upper Body Dynamic Exercise on Lymphatic Function in Healthy Females

BACKGROUND

Little is known about the acute effects of exercise on the lymphatic system. Thus, the purpose was to determine the effect of low versus high intensity upper body exercise on lymphatic function in healthy females.

METHODS AND RESULTS

On separate days, eight females performed either HI: 12 repeated sets of arm cranking for 2.5 min at 0.6 W.kg-1, followed by 2.5 min of rest; or LO: 12 repeated sets of arm cranking for 2.5 min at 0.3 W.kg-1, followed by 2.5 min of rest. One min spot views were taken with a gamma-radiation camera immediately after injection of 99mTc-antimony colloid and every 10 min thereafter to measure the clearance rate (CR) from the first and fourth finger-web of each hand. Radiopharmaceutical uptake in the axillary regions (AX) at 65 min postinjection was also measured. Clearance from the injection sites was linear and expressed as a slope (% administered activity.min-1). HI resulted in significantly greater CR (-0.24%.min-1+/-0.06) than LO (-0.19%.min-1+/-0.05; p=0.003). A similar trend was seen in AX (HI: 6.3%+/-1.6, LO: 4.8%+/-1.1, p=0.004).

CONCLUSIONS

The results indicate that an arm cranking protocol of higher intensity is more effective in promoting lymphatic clearance from the hand. Further, the high intensity protocol may be useful in the functional evaluation of the lymphatic system in breast cancer survivors and warrants further investigation.

Imaging of lymphatic vessels in breast cancer-related lymphedema: intradermal versus subcutaneous injection of 99mTc-immunoglobulin

OBJECTIVE

The disordered physiology that results from axillary lymph node clearance surgery for breast cancer and that leads to breast cancer-related lymphedema is poorly understood. Rerouting of lymph around the axilla or through new pathways in the axilla may protect women from breast cancer-related lymphedema. The aim of the study was to compare intradermal with subcutaneous injection of technetium-99m ((99m)Tc)-labeled human polyclonal IgG (HIG) with respect to lymphatic vessel imaging.

MATERIALS AND METHODS

Six women with breast cancer-related lymphedema underwent unilateral upper limb lymphoscintigraphy, using a web space injection of (99m)Tc-labeled HIG, after intradermal and subcutaneous injections on separate occasions. Multiple sequential images were obtained of the affected upper limb and torso over 3 hr on each occasion. Accumulation of activity in blood was quantified from venous blood samples taken from the opposite arm.

RESULTS

Imaging after intradermal injection clearly showed discrete lymphatic vessels in five of six patients, in contrast to imaging after subcutaneous injection, which did not show any discrete vessels in any patient. Intradermal injection resulted in more rapid visualization of cutaneous lymph rerouting than subcutaneous injection in six of six patients. Recovery of injected (99m)Tc-labeled HIG in venous blood was greater after intradermal injection in six of six patients.

CONCLUSION

In patients with breast cancer-related lymphedema, lymphatic vessels are more clearly depicted after intradermal than subcutaneous injection as a result of direct access of radiotracer to dermal lymphatics. This finding has implications for imaging lymphatic vessel regeneration and lymph rerouting.

A quantitative lymphoscintigraphic evaluation of lymphatic function in the swollen hands of women with lymphoedema following breast cancer treatment

In BCRL (breast cancer-related lymphoedema), arm swelling is unevenly distributed and some regions are partly or entirely spared. In particular, the hand may or not be swollen, but when involved functional impairment can be substantial. We have found previously that, when the ipsilateral hand is spared of swelling (in a limb with swelling proximal to the hand), the local lymph drainage rate constant (k) is at least as high as in the contralateral hand, contrary to the traditional 'stopcock' concept of reduced lymph drainage from the whole limb. In the light of this finding, we have investigated lymph drainage in the hands of eight women with BCRL and moderate-to-severe hand swelling, using gamma-camera quantitative lymphoscintigraphy. Images showed pronounced superficial activity in the ipsilateral swollen arms of most patients, indicating dermal backflow. k for 99mTc-labelled hIgG (human IgG) measured over 5 h in the subcutis of the ipsilateral swollen hand was 34+/-24% less than in the contralateral hand (P=0.013). Activity measured in the ipsilateral swollen forearm increased progressively, but there was very little increase in the contralateral forearm, indicating retention of 99mTc-labelled hIgG in the swollen forearm. It is concluded that lymphatic function in the swollen hand is impaired, and that there appears to be two populations of women with BCRL, i.e. spared-hand and swollen-hand, irrespective of the cancer treatment received.

Short-term effects of axillary lymph node clearance surgery on lymphatic physiology of the arm in breast cancer

It is not known why some women develop breast cancer-related lymphedema (BCRL) of the arm, whereas others having similar treatment do not. We speculated that increased uptake of protein into local blood may protect against BCRL. Sixteen women were given bilateral subcutaneous hand webspace injections of polyclonal immunoglobulin (HIgG), (99m)Tc-HIgG on one side and (111)In-HIgG on the other, before and 3 mo after axillary clearance surgery. The rates of clearance of activity from the depot (k) and accumulation in central blood (b(contra)) were measured using a scintillation probe and bilateral antecubital vein blood sampling, respectively. Activity accumulating in blood ipsilateral to the injected side, in excess of central blood activity (b(ipsi)) was also calculated as a measure of local vascular uptake. The k correlated with b(contra), but neither changed in response to surgery. However, b(ipsi) for injections of (99m)Tc-HIgG into the affected arm increased in all seven patients in whom data were available (0.018 +/- 0.006 to 0.038 +/- 0.007%/min; P < 0.05); indeed, in five of these seven, b(ipsi) paradoxically exceeded b(contra), and none developed BCRL at 3-yr follow-up. We conclude that uptake of protein into local blood and/or proteolysis increases after axillary surgery and may protect against BCRL.

The efficacy of 99mTc-HIG for sentinel lymph node mapping in breast cancer patients

OBJECTIVE

To evaluate the efficacy of Tc-HIG on SLN identification in patients with early-stage breast cancer.

MATERIALS AND METHODS

Seventeen women (18 tumours) with early-stage breast cancer were included. On the day of the operation, 111 MBq Tc-HIG was injected around the tumour or biopsy scar in all patients. Subsequently, dynamic lymphoscintigraphic images were taken for 30 min. After this, static images were recorded at 15-20 min intervals until the SLN was visualized. Patients were taken to the operating room 2-4 h after radiopharmaceutical injection. Before the incision, 5 ml of isosulfan blue dye solution was injected peritumourally in all subjects. Aided by blue dye and gamma probe SLN detection was done during the operation.

RESULTS

In 17/18 tumours, SLN was detected with Tc-HIG lymphoscintigraphy. The mean visualization time for axillary SLNs was 49.94+/-11.25 min and for internal mammary SLNs was 52.50+/-10.60 min. In 15 of the tumours, only one SLN was detected in the axillary region. However, in two tumours, SLNs were found in both axillary and internal mammary regions. With blue dye mapping, axillary SLNs were found in 17/18 tumours. With the application of intraoperative gamma probe, all axillary and internal mammary SLNs were detected in 18 tumours.

CONCLUSION

We conclude that Tc-HIG may be a suitable agent for SLN detection by lymphoscintigraphy and intraoperative gamma probe application in early-stage breast cancer patients.

Lymphoscintigraphy to Evaluate the Effects of Upper Body Dynamic Exercise and Handgrip Exercise on Radiopharmaceutical Clearance from Hands of Healthy Females

BACKGROUND

Currently, there is not a standardized protocol to evaluate lymphatic function in women. Therefore, the purpose of this study was to evaluate the effects of arm crank ergometry (AC) and handgrip contractions (HG) on radiopharmaceutical clearance from the hands of six healthy females.

METHODS AND RESULTS

On separate days, subjects performed AC (six repeated bouts of arm cranking for 5 min at 0.6 Watts.kilogram(-1) (W.kg(-1)) followed by 5 min rest) or HG (twelve repeated bouts of 75 contractions in 2.5 min at 50% MVC followed by 2.5 min of rest). HG was done with the right hand only while the left hand served as a control (CON). Prior to the start of exercise, (99m)Tc-antimony colloid was injected into the first and fourth finger-web of each hand, and 1 min spot views were taken immediately after the injection and then again every 10 min over 60 min. Clearance from the injection sites was linear and expressed as a slope (% administered activity.min(-1)). Significantly faster clearance was observed with AC (rt = -0.27 +/- 0.03 %.min(-1); left = -0.29 +/- 0.06 %.min(-1)) compared to both HG (-0.18 +/- 0.03 %.min(-1)) and CON (-0.14 +/- 0.05 %.min(-1); p = 0.000).

CONCLUSION

The results indicate that AC may be more effective in promoting lymphatic clearance from the hand and may be a useful protocol to challenge the lymphatic system in breast cancer survivors.

Exercise and the Lymphatic System

This article summarises the current research on the lymphatic system related to exercise and critically evaluates the implications for exercise performance by breast-cancer survivors. The primary role of the lymphatic system during exercise is to assist in the regulation of tissue volume and pressure by carrying fluid and plasma proteins that have leaked into the interstitial space from tissues back to the cardiovascular system. During steady-state exercise in humans, lymph flow has been shown to increase to levels approximately 2- to 3-fold higher than at rest. Although the lymphatic system does not typically limit exercise performance in the normal population, the function of this system can be impaired in 27-49% of women who have survived breast cancer. Breast cancer-related lymphoedema (BCRL) is a chronic swelling that can occur in the ipsilateral hand or arm of women treated for breast cancer and results in a number of physical and psychological sequelae. Exercise was once believed to be a factor in the development of BCRL as it was thought that the damage to the axillary lymphatics from breast-cancer treatment resulted in a primary obstruction to lymph flow. However, the exact aetiology and pathophysiology of BCRL appears to be multi-factorial and not as simple as a 'stop-cock' effect. Furthermore, recent studies have shown that participating in vigorous, upper-body exercise is not related to an increase in arm volume, which would indicate the development of BCRL. It is still not known, though, how long-term exercise affects lymphatic system function in breast-cancer survivors with and without BCRL.

Development of 99mTc-neomannosyl human serum albumin (99mTc-MSA) as a novel receptor binding agent for sentinel lymph node imaging

BACKGROUND AND AIM

Various mannose receptor-binding agents, for example 99mTc-diethylenetriaminepentaacetic acid (DTPA)-mannosyl-polymer, have been developed for sentinel lymph node (SLN) imaging. In order to simplify the synthesis and labelling procedure and to improve the biological properties, we developed a novel mannose receptor-binding agent, 99mTc-neomannosyl human serum albumin (99mTc-MSA), for SLN imaging.

METHODS

MSA was synthesized by conjugating mannopyranosylphenylisothiocyanate to human serum albumin (HSA). After reducing MSA with beta-mercaptoethanol and PD-10 column purification, a medronate solution containing stannous fluoride was added, divided into aliquots and freeze-dried. Reduced MSA was labelled with 99mTc-pertechnetate solution. The stability was checked for 24 h at 37 degrees C in human serum. The biodistribution of 99mTc-MSA in mice was investigated by intravenous injection through the tail vein and subcutaneous injection into the foot pad. The biodistributions of 99mTc-HSA and 99mTc-antimony sulphur colloid (99mTc-ASC) were also investigated for comparison. Dynamic whole-body images were obtained for 30 min after subcutaneous injection into the rats' foot pads.

RESULTS

The number of mannose molecules conjugated per MSA was 15.9. The number of thiol groups produced was 19.4 per MSA after reduction with beta-mercaptoethanol. Labelling yields were always higher than 97%. 99mTc-MSA was stable for 24 h at 37 degrees C in human serum. The biodistribution in mice after intravenous injection showed high liver uptake (50.7+/-5.5% and 42.7+/-3.7% injected dose per gram at 10 and 60 min, respectively). 99mTc-MSA and 99mTc-ASC showed high accumulation in the lymph nodes after subcutaneous injection, whereas 99mTc-HSA and Tc-tin colloid did not, in both biodistribution and imaging studies.

CONCLUSIONS

We have successfully developed a novel 99mTc-MSA for lymphoscintigraphy. The results of animal studies show that 99mTc-MSA has promising properties for SLN imaging.

Measurement of the extraction fractions of nanocolloid and polyclonal immunoglobulin by axillary lymph nodes in patients with breast cancer

BACKGROUND

99mTc nanocolloid (99mTc-NC) is the most widely used tracer for lymphoscintigraphy, although others have been proposed, including radiolabelled proteins such as human serum albumin and polyclonal human immunoglobulin G (HIG). The extraction fraction of such tracers by individual nodes is clearly important but has not previously been measured in humans.

METHODS

Patients scheduled for axillary clearance surgery (three groups) received dual-labelled radiotracers 2-4 h before surgery: group 1 (3 patients) received 99mTc-NC (10 MBq) and 111In-HIG (2 MBq) as a mixture (0.2 ml) into the breast parenchyma above the primary tumour; group 2 (3 patients) received 99mTc-HIG (10 MBq) and 111In-HIG (2 MBq) as a mixture (0.2 ml) into the breast parenchyma above the primary tumour; and group 3 (4 patients) received 99mTc-HIG (10 MBq) and 111In-HIG (2 MBq) separately (both 0.2 ml) into the breast parenchyma above the tumour and the intradermal plane at the areola. All resected nodes were counted for Tc and In in a well-type scintillation counter. In group 1, nodes were ranked according to their Tc uptake. In groups 2 and 3, nodes were ranked separately according to their respective Tc and In uptakes. If nodes are arranged in linear order and each node extracts a constant fraction of incoming tracer, then the activity in the nodes would decrease exponentially with an individual nodal extraction fraction, E, equal to 1-e(-k), where k is the rate constant of decrease.

RESULTS

In the first group, 99mTc-NC and 111In-HIG identified the same sentinel and second echelon nodes. The observed decrease in nodal activity was exponential in all groups, at least for the first five nodes. Average values for E, based on the first five nodes were 0.69 (range 0.57-0.89; n=3) for 99mTc-NC and 0.45 (0.15-0.70; n=17) for HIG (irrespective of label) (Wilcoxon rank sum, P=0.02). With respect to HIG, there was no significant difference in E between 99mTc and 111In or between deep and superficial injections in group 3.

CONCLUSION

Although HIG has an extraction fraction less than 99mTc-NC, the value of E is still high enough to make HIG a useful tracer for lymphoscintigraphy, especially for identifying second echelon nodes in addition to sentinel nodes and for imaging lymphatic vessels as well as lymph nodes.

Variation in lymphatic function may predispose to development of breast cancer-related lymphoedema

AIMS

Breast cancer-related lymphoedema (BCRL) remains a common complication of breast cancer treatment. Many features of this condition remain poorly understood, such as why only approximately 25% of women are affected after similar treatment, and the phenomenon of 'sparing', in which regions of an otherwise swollen arm, most commonly the hand, remain unaffected. This study uses dual-isotope lymphoscintigraphy, involving measurement of rate of clearance of radiolabelled protein from a subcutaneous depot and subsequent appearance in blood, to quantify alterations in lymphatic function in women with BCRL, and to further investigate differences between those in whom the hand is involved with swelling and those in whom it is spared.

METHODS

Participants received a depot injection of human immunoglobulin G in the dorsum of both hands, labeled with technetium-99m on one side and indium-111 on the other. Rates of clearance from the depot and appearance in venous blood were measured at regular intervals over a 3 h period.

RESULTS

A total of 18 women with a history of BCRL were studied. Significant reductions in both depot clearance and venous appearance were observed in the affected arm compared with the unaffected contralateral control. On sub-group analysis, significant differences were also observed between swollen and spared hand groups, both for the affected and unaffected contralateral arm.

DISCUSSION

This study, as well as confirming impaired lymphatic function in arms affected by BCRL, also shows underlying variation in lymphatic function in the unaffected contralateral arm, between those with and without hand sparing. This raises the possibility that the risk of developing BCRL may be, in part, pre-determined.

Finding an optimal method for imaging lymphatic vessels of the upper limb

Lymphoscintigraphy involves interstitial injection of radiolabelled particulate materials or radioproteins. Although several variations in the technique have been described, their place in clinical practice remains controversial. Traditional diagnostic criteria are based primarily on lymph node appearances but in situations such as breast cancer, where lymph nodes may have been excised, these criteria are of limited use. In these circumstances, lymphatic vessel morphology takes on greater importance as a clinical endpoint, so a method that gives good definition of lymphatic vessels would be useful. In patients with breast cancer, for example, such a method, used before and after lymph node resection, may assist in predicting the development of breast cancer-related lymphoedema. The aim of this study was to optimise a method for the visualisation of lymphatic vessels. Subcutaneous (sc) and intradermal (id) injection sites were compared, and technetium-99m nanocolloid, a particulate material, was compared with (99m)Tc-human immunoglobulin (HIG), which is a soluble macromolecule. Twelve normal volunteers were each studied on two occasions. In three subjects, id (99m)Tc-HIG was compared with sc (99m)Tc-HIG, in three id (99m)Tc-nanocolloid was compared with sc (99m)Tc-nanocolloid, in three id (99m)Tc-HIG was compared with id (99m)Tc-nanocolloid and in three sc (99m)Tc-HIG was compared with sc (99m)Tc-nanocolloid. Endpoints were quality of lymphatic vessel definition, the time after injection at which vessels were most clearly visualised, the rate constant of depot disappearance ( k) and the systemic blood accumulation rate as measured by gamma camera imaging over the liver or cardiac blood pool. Excellent definition of lymphatic vessels was obtained following id injection of either radiopharmaceutical, an injection route that was clearly superior to sc. Differences between radiopharmaceuticals were less clear, although after id injection, (99m)Tc-HIG gave images that were marginally but significantly better than those given by (99m)Tc-nanocolloid. Image quality correlated inversely with time after injection at which the best image was obtained, consistent with the notion that good vessel definition was dependent on a "narrow" bolus width. k was approximately three times higher after id injection than after sc injection but it was not significantly different between radiopharmaceuticals for either injection route. Intradermal (99m)Tc-HIG gave a cardiac blood pool signal that, over the first 60 min, increased about five times faster than that with sc (99m)Tc-HIG, but no clear difference was observed in the rate of increase in hepatic activity between id (99m)Tc-nanocolloid and sc (99m)Tc-nanocolloid. We conclude that id injection provides rapid access of radiotracers to lymphatic vessels, which is ideal for imaging lymphatic vessel morphology. (99m)Tc-HIG is marginally superior to nanocolloid for this purpose and, in drainage basins from which lymph nodes have been excised, is not handicapped by a potentially inferior ability, compared with radiocolloid, to image lymph nodes.