Definitions and criteria
Before performing this retrospective study, different definitions and criteria were set up based on the published literature. Diagnosis criteria for LL were milky fluid leakage with triglycerides above 110 mg/dL and/or positive detection of the chylomicron [8, 9]. The technical success of TL was defined as uneventful cannulation of the lymphatic vessels with injected contrast opacification of the lymphatics extending beyond the site of the identified extravasation [10, 11]. The technical success of percutaneous CT-guided ALVS was defined as the distribution of the sclerosant around the target lymphatic vessel which was assessed under the CT scan [6]. The clinical success of TL or percutaneous CT-guided ALVS was defined as complete cessation of lymph leakage after the procedure or a gradual decrease resulting in the withdrawal of the drainage tube in 3 weeks and lack of the need for other treatment, such as conservative medical nutrition therapy, e.g., a fat-free or low-fat oral supplement with medium-chain triglycerides (MCTs), enteral feeding and/or parenteral nutrition with a high percentage of MCTs etc., and surgical ligation. Further, the clinical failure was defined as no change or an increase of the LL in the follow-up, with the necessity of a conservative treatment or any other additional treatment (e.g., surgical revision, radiotherapy) [5, 12, 13].
Study population
The institutional digital databases including the General Electric picture archiving and communication system and centricity radiology information system databases (General Electric Medical Systems, Buckinghamshire, UK) were retrospectively retrieved for the period from May 2011 to September 2018. The inclusion criteria were as follows: (1) patients diagnosed with postoperative LL, (2) technically successful TL performed for the postoperative LL with the intention to cure the LL, (3) percutaneous CT-guided ALVS performed after the identification of clinical failure of the previous TL.
The electronic data of 201 patients who were diagnosed with postoperative LL and underwent therapeutical TL was retrieved by two independent radiologists (C.M.S. and F.P., with more than 10 and 8 years of experience in interventional radiology, respectively).
Therapeutic TL
The therapeutic TL was performed for the patients with clinically diagnosed lymphatic leakage from the lower extremity, iliac, abdominal para-aortic lymphatics, or thoracic duct [14]. Informed consent was obtained from all patients. The details of the TL technique have previously been described [6, 15]. A period of 20–40 min after the injection of 1 mL of 1:3 mixture of methylene blue dye and local anesthetic between the interdigital spaces of the foot, an accessible lymphatic vessel on the dorsum of the foot was examined. Then, a small incision was made and the lymphatic vessel was carefully dissected free and catheterised with the use of a 26-gauge intravenous cannula (BD Vasculon Plus; BD, Heidelberg, Germany). Afterwards, the iodinated oil (Lipiodol, Guerbet Germany, Sulzbach, Germany) was manually injected with the velocity of approximately 0.5–2.0 mL/min to opacify the lymphatic vessels under fluoroscopy (Artis Zee, Siemens Healthineers, Erlangen, Germany). The maximal volume of the iodinated oil was less than 20 mL according to the instructions for use and in order to prevent fatal pulmonary embolisation [4]. The needles were removed, and the wounds were sutured after the accomplishment of the injection. After the iodinated oil reached the leakage level or above as observed on the TL images, the post-TL CT scan (Somatom Definition DS; Siemens Healthineers, Erlangen, Germany) was performed for identifying the site of LL and the afferent lymphatic vessel with the assistance of the TL images [6, 16]. All the procedures were performed by the same team of interventional radiologists with experience of over 20 years in lymphangiography, lymphatic sclerotherapy, and embolisation.
Indication and contraindications to percutaneous CT-guided ALVS
The indication of percutaneous CT-guided ALVS was the definite identification of the leakage site and the afferent lymphatic vessels feeding the leakage on the post-TL CT images [6]. The contraindications included the proximity of the target area to the important vessels or nerves and anticoagulant/antithrombotic medication [6].
Percutaneous CT-guided ALVS
The percutaneous CT-guided ALVS was performed after the clinically failed TL treatment. The technique was described before and an illustration is shown in Fig. 1 [6]. Informed consent was obtained from all patients. The procedure was performed under local anesthesia, and 7.5 mg piritramide was intravenously injected before the procedure. Nasal-cannula oxygen therapy was performed with a velocity of 2 to 3 L/min during the procedure. The noninvasive multifunctional electrocardiogram, pulse oximetry, and blood pressure monitor were routinely performed during the procedure. The preoperative CT was performed after the placement of a radiopaque optical marker on the skin of the patient, and the target lymphatic vessel was confirmed with the assistance of the previous CT images. The CT parameters were set as follows: single-energy technique, tube voltage 120 kVp, effective tube current-time product from 16 to 383 mAs. Images were reconstructed as along the axial plane with a slice thickness of 3 mm and increment of 3 mm. All reconstructions were performed in a medium soft-tissue kernel (B31f; Siemens Medical Solutions, Siemens, Forchheim, Germany).
Then, the ideal access point and route were meticulously chosen to avoid unnecessary injury to any other organ or structure. After administration of local anesthesia (Xylocaine 1%, Astra Zeneca, Wedel, Germany), the 21- or 22-gauge Chiba needle (15 or 20 cm in length) or the 21-gauge hypodermic needle (5 cm in length) was used to puncture with the tip placed as close as possible to the afferent lymphatic vessels, depending on the depth of the target lymphatic vessels. Then, approximately 1–4 mL of a 1:9 mixture of iomeprol 300 mgI/mL (Iomeron 300, Bracco Imaging Deutschland, Konstanz, Germany) and local anesthetic was injected to observe whether the contrast dispersed around the target lymphatic vessel without distribution into any other important tissue or structure. Afterwards, 95% ethanol (B. Braun Melsungen, Melsungen, Germany) as sclerosant agent was injected with a volume lower than 5 mL [6]. After the sclerotherapy, a CT scan was performed again to assess possible intraprocedure complications. All the procedures were performed by a team of interventional radiologists as mentioned above.
After the procedure, patients were transferred to the ward and asked for a 2-h bed rest with compression of the puncture site as well as noninvasive multifunctional electrocardiogram, pulse oximetry, and blood pressure monitor. If the cardiorespiratory manner was stable after 2 h; then, the patient was allowed to leave the bed. Analgesia was performed depending on the clinical situation.
Follow-up
After ALVS therapy, the daily chyle drainage output was recorded, and intermittent CT/x-ray was carried out. After discharge, the patients were asked for a regular recheck at the outpatient department and/or after hospitalisation every 1 to 3 months lasting for half a year.
Study goals
After the retrieval of patient involvement consent, patient information was collected, including age, sex, diagnosis, surgery, location of the LL, daily chyle/lymph output, the clinical outcome of ALVS, and complications, etc. The study goals of the ALVS included technical success rate, clinical success rate, the interval between the ALVS and the cure of LL, and the complications. The procedure-related complications were collected and classified into minor and major complications in accordance with the criteria of the Society of Interventional Radiology [17].
Statistical analysis
Statistical analyses were performed using the IBM SPSS Statistics Software (version 24; IBM, New York, USA). Quantitative data were presented as mean ± standard deviation, while the counting data were presented as count and percentage of the total. Because this was not a comparative study, only descriptive analysis was used. For the rates of technical and clinical success, the 95% confidence interval (CI) was calculated according the Clopper-Pearson test.