Lymphoscintigraphy of Chylous Anomalies: Chylothorax, Chyloperitoneum, Chyluria, and Lymphangiomatosis-15-Year Experience in a Pediatric Setting and Review of the Literature

Resolution of chyluria due to congenital malformation with a minimally invasive procedure

Milky white urine is most commonly due to chyluria secondary to filariasis, though other causes of milky white urine and other etiologies of chyluria must be considered. Evaluation of a 3-year-old girl with milky white urine demonstrated chyluria, but testing for filariasis was negative despite a history of travel to an endemic region. Magnetic resonance lymphangiography demonstrated a congenital lymphatic malformation, which was repaired following this minimally invasive imaging technique.

Lymphoscintigraphy Findings are Associated with Outcome in Children with Chylothorax After Cardiac Surgery

Postoperative chylothorax in patients with congenital heart diseases (CHD) results in poor outcomes if anatomical and functional abnormalities of the lymphatic system are present. While these abnormalities are typically diagnosed by intranodal lymphangiography and dynamic contrast magnetic resonance lymphangiography, the usefulness of lymphoscintigraphy in these patients has not been evaluated. Between January 2019 and December 2021, 28 lymphoscintigraphies were performed in our institution for investigating prolonged pleural effusion after cardiac surgery. The images were assessed by three board-certified pediatric cardiologists retrospectively to determine the likelihood of a central lymphatic flow disorder. The likelihood was scored (range 1-3) based on structural abnormalities and congestive flow in the lymphatic system. Those scores were summed and the likelihood was categorized as low to intermediate (< 8 points) or high (8 or 9 points). Median age at lymphoscintigraphy was 129 days (IQR, 41-412 days), it was performed at a median of 22 days (IQR, 17-43) after surgery, and median score was 6 points (IQR, 4-7.5). Kendall's coefficient of concordance (0.867; p < 0.05) indicated high inter-rater reliability. Overall survival at 6 months after surgery was 92.5% in the low-to-intermediate group but 68.6% in the high group (p < 0.05), and duration of postoperative thoracic drainage was 27 and 58 days, respectively (p < 0.05). Lymphatic abnormalities detected by lymphoscintigraphy were associated with poorer outcomes. Lymphoscintigraphy was thought to be useful in assessing anatomic and functional lymphatic abnormalities, despite its minimal invasiveness.

Utility of 99mTc-Sulfur Colloid Lymphoscintigraphy and SPECT/CT in Chylothorax and Chylous Ascites

Purpose

To assess the diagnostic efficacy of 99mTc-sulfur colloid lymphoscintigraphy in chylothorax and chylous ascites, and the utility of single-photon emission computed tomography-computed tomography (SPECT/CT) in localizing the sites of leaks.

Methods

Data from patients who underwent lymphoscintigraphy for clinical suspicion of chylothorax or chylous ascites were retrospectively analyzed. Biochemical fluid analysis was taken as the reference standard. Pleural fluid triglyceride level > 110 mg/dL (with pleural fluid/serum ratio > 1) and a cholesterol level < 200 mg/dL (with pleural fluid/serum ratio < 1) were considered confirmatory for chylothorax. Ascitic fluid triglyceride level > 200 mg/dL with a low cholesterol level (ascites fluid/serum ratio < 1) was considered confirmatory for chylous ascites.

Results

26 patients (15 males, 57.7%) aged 9 months to 68 years were enrolled in the study. Based on the reference standard, 17 had chylothorax or chylous ascites (9 with surgical history). Lymphoscintigraphy was positive in 16 (with 1 false positive) and negative in 10 (with 2 false negatives). The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of lymphoscintigraphy were 88.2% (63.6-98.5%), 88.9% (51.8-99.7%), 80.0% (51.6-93.8%), 93.8% (70.1-99.0%), and 88.5% (69.9-97.6%), respectively. SPECT/CT could localize sites of leaks in 61.5% (8/13) with a localization rate of 77.8% (7/9) and 25.0% (1/4) in patients with surgical and nonsurgical causes, respectively.

Conclusion

99mTc-sulfur colloid lymphoscintigraphy is a highly efficacious noninvasive modality to diagnose chylothorax or chylous ascites with a high positive predictive value. SPECT/CT could localize the sites of leaks more frequently in patients with surgical causes.

Lymphoscintigraphy findings in patients with chylothorax: influence of biochemical parameters

BACKGROUND

Chylothorax is a condition that can be challenging to diagnose due to its nonspecific clinical presentation. Several biochemical parameters of chylous pleural effusion have been identified as important indicators for the diagnosis of chylothorax. Lymphoscintigraphy is utilized to assess chylothorax and determine the location of chyle leakage. The present study aimed to evaluate the correlation between the biochemical parameters of chylous pleural effusion and 99mTc-dextran (99mTc-DX) lymphoscintigraphy in diagnosing chylothorax.

MATERIAL AND METHODS

A total of 120 patients were enrolled in the study, 83 of the patients with unilateral chylothorax, and 37 with bilateral chylothorax. All patients underwent both 99mTc-DX lymphoscintigraphy and pleural effusion laboratory analysis. The 99mTc-DX lymphoscintigraphy images were categorized as positive or negative groups based on the presence or absence of abnormal radioactive tracer accumulation in the thorax, respectively. The biochemical parameters of the two groups were subsequently compared.

RESULTS

Among these patients, 101 (84.17%) had exudative effusions, while 19 (15.83%) had transudative effusions, as determined by the levels of pleural effusion protein, lactate dehydrogenase and cholesterol. Abnormal tracer accumulation in thorax was observed in 82 patients (68.33%). Our findings indicated that lymphoscintigraphy results were not associated with exudative and transudative chylothorax (P = 0.597). The lymphoscintigraphy positive group displayed significantly higher levels of pleural effusion triglyceride and pleural effusion triglyceride/serum triglyceride ratio in all biochemical parameters, compared to the negative group (P = 0.000 and P = 0.005). We identified cutoff values of 2.870 mmol/L for pleural effusion triglycerides and 4.625 for pleural effusion triglyceride/serum triglyceride ratio, respectively, which can facilitate differentiating the positive and negative cases on lymphoscintigraphy.

CONCLUSION

Lymphoscintigraphy technique is a dependable diagnostic tool for the qualitative assessment of chylous pleural effusion. Higher pleural effusion triglyceride level and pleural effusion triglyceride/serum triglyceride ratio indicate a positive result in patients with chylothorax on lymphoscintigraphy, with the cutoff values of 2.870 mmol/L and 4.625 aiding in the diagnosis.

Insufficient hepatic uptake in pediatric patients on lymphoscintigraphy

BACKGROUND

To demonstrate the association between pediatric outcomes and tracer hepatic uptake as a marker of systemic circulation in lymphoscintigraphy.

METHODS

We included 31 initial lymphoscintigraphic studies. We compared the presence or absence of hepatic uptake between deceased and survived patients in both early and delayed images using Fisher's exact test. Kaplan-Meier survival analysis was performed based on imaging results, and these curves were compared using the log-rank test. The primary endpoint was death and the survival period was defined from the day of examination to the day of the last visit or death.

RESULTS

Of 31 patients, six died. Hepatic uptake was significantly different in both early and delayed images (early images, died [with/without visualization] vs. survived [with/without visualization], 0/6 vs. 13/12, P = 0.028; delayed images, died [with/without visualization] vs. survived [with/without visualization], 2/4 vs. 22/3, P = 0.014) between deceased and survived patients. Survival periods were significantly different between the two groups with and without hepatic uptake in early and delayed images (with/without visualization in early imags = 1,177.1 ± 773.8 days/426.7 ± 419.8 days, P = 0.008 and with/without visualization in delayed images = 821.3 ± 738.0 days/467.4 ± 452.4 days, P = 0.003).

CONCLUSIONS

Visualization of hepatic uptake in both early and delayed lymphoscintigraphy is associated with patient outcomes. Hepatic uptake could represent tracer inflow into the systemic circulation, indicating preservation of the connection between the lymphatic system and the systemic circulation. Physicians should evaluate these findings carefully on lymphoscintigraphy.

Lymphoscintigraphy for the evaluation of limb lymphatic flow disorders: Report of technical procedural standards from an Italian Nuclear Medicine expert panel

Lymphoscintigraphy represents the "gold standard" for diagnosis of lymphedema, but an important limitation is the lack of procedural standardization. The aim of this Italian expert panel was to provide a procedural standard for lymphoscintigraphy in the evaluation of lymphatic system disorders. Topic anaesthetic gels containing lidocaine should be avoided. Patients should remove compressive dressings. Total recommended activity for 99mTc-nanocolloid administration in adults is 74MBq, or 37MBq per limb and per investigated compartment, in single or multiple aliquots. 2-3 subcutaneous injections should be performed (II-III±I interdigital space of each hand/foot), avoiding intravascular injection. Deep lymphatic system of lower limbs should be evaluated in presence of dermal back-flow or lymphatic stasis (1-2 subfascial administrations in retro-malleolar or plantar region). Planar images should be acquired from injection site to liver with whole-body or serial static acquisitions 20' and 90' after subcutaneous administration. Additional information on lymphatic pathways is obtained after a quick and/or prolonged exercise protocol. SPECT/CT is recommended to study the thoracic, abdominal and pelvic territories. When required, deep lymphatic system of lower limbs should be evaluated with static acquisition 90' after subfascial administration. The report should describe administration and imaging procedure, exercise protocol, qualitative and semi-quantitative analysis (wash-out rate, transport index), potential sources of error. Due to the essential role fulfilled by lymphoscintigraphy in clinical management of primary and secondary lymphedema, an effort for the standardization of this technique should be made to provide the clinicians with a homogeneous and reliable technical methodology.